Indoor Hydroponic Setup

Getting Started In Hydroponics

This e-book will take you on a journey, almost like going down a garden path, and help match the right system to your situation. Along the way you will discover the most powerful system, the easiest to build system, and the most forgiving system for maintenance. And the book will help you choose which system is right for you. You'll discover. The quickest, easiest hydroponics system to build. You can get started in hours rather than days and the system is built from common materials so you can save money. 5 ways you can get started in hydroponics on a pauper's budget. You don't have to get the most complex system to get incredible results. The e-book has 2 plans that can be built out of common materials you may already have. You can get the rest at Home Depot. Which crops to grow and which to stay away from. You can grow just about anything with hydroponics but some plants will take over, stealing light and space from smaller plants. This e-book will give you insights on which plants are the easiest. and tastiest. Forbidden Hideaway. The last chapter in the book shows you how to create a space in your home to grow plants that nobody will know about. To the outside world you are an ordinary neighbor. But inside the Grow Box a different world exists that makes plants grow like crazy. More here...

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Of xylem sap of barley and rice grown hydroponically under varied concentrations of iron

As shown in the previous section 4.1, the concentration of PS was much higher than that of Fe in xylem sap of -Fe barley. The ratio of the concentration of PS Fe varied depending on Fe nutritional status of the plant. In order to obtain data for the PS Fe ratio as affected by the Fe status of the plant, the xylem sap from grasses grown with various concentrations of Fe (0, 1, 10, 100 M) in hydroponic culture was collected and analyzed. Iron sources in the hydroponics media for barley and rice were EDTA-Fe (Kawai et al., 1993) and citrate-Fe (Alam et al., 2003), respectively. Table 14-2. Amounts and ratios of phytosiderophores and Fe of xylem sap of barley and rice. Xylem sap was collected for 3 hours from 36 plants of barley or 96 plants of rice grown hydroponically in a greenhouse. Iron sources for the cultivation were EDTA-Fe for barley and citrate-Fe for rice. Table 14-2. Amounts and ratios of phytosiderophores and Fe of xylem sap of barley and rice. Xylem sap was collected for 3...

Thesis On Chilli Cultivation With Drip Irrigation

Z., ElBeltagy, A. S. and Burge, S. W. (1993) Relation between water use efficiency of sweet pepper grown under nutrient film technique and rockwool under protected cultivation. Acta Horticulturae, 323, 89-95. Basaccu, L. and Garibaldi, G. (1971) The effects of various cultural practices on the yield of capsicum in the presence or absence of attack by Verticillium dahlia. Annali dellafacota di scienze Agrarie della Universita d.gen studi di Torina, 141 162. Batchelor, C., Lovell, C. and Murata, M. (1997) Simple micro irrigation techniques for improving irrigation efficiency on vegetable gardens. Agril. Water Management, 32, 37 48. Biles, C. L., Lindsey, D. L. and I.iddell, C. M. (1992) Control of Phytopathon root rot of chilli peppers by irrigation practices and fungicides. Crop Protection, 11, 225-228. Cabello, T., Gomez, M., Barranco, P., Lucos, M. and Belda, J. E. C. (1997) Evaluation of Oxamyl against Homoptera pests in green house grown pepper...

Hydroponics

Hydroponics is the practice of growing plants without soil. Plants may be suspended in water or grown in a variety of solid, inert media, including vermiculite (a mineral), sand, and rock wool (fiberglass insulation). In these cases, water that permeates the medium provides the nutrients, while the medium provides support for root structures. Hydroponics allows precise control of nutrient levels and oxygenation of the roots. Many plants grow faster in hydroponic media than in soil, in part because less root growth is needed to find nutrients. However, the precise conditions for each plant differ, and the entire set up must be in a greenhouse, with considerable investment required for lights, tubing, pumps, and other equipment. Sprouts growing in a hydroponic hot house in Japan. Sprouts growing in a hydroponic hot house in Japan. While hydroponics is as old as the hanging gardens of Babylon, modern hydroponics was pioneered by Julius von Sachs (1832-1897), a researcher in plant...

Drip irrigation

While the high initial investment associated with drip irrigation may appear prohibitive for pineapple culture, in areas where water is limited or expensive and the need for irrigation may extend for many months, the investment will pay good dividends. Drip irrigation allows precise placement of water in the root zone in volumes that match the crop's consumptive demand. Drip irrigation is especially effective during the first few months after planting, when a consistent but low-volume supply of water is needed for the developing root system. Drip-irrigation systems involve the following major components a water source, a filtration system if particulate matter that can clog emitters is present, chlorination to prevent microbial growth in the drip tubes, a system of in-field distribution pipes, which bring water at the correct volumes and pressures to various parts of the fields, and the emitter tubes, which are usually buried just below the soil surface between two lines of plants....

Seed Research a Brief History

Research, if any, on seeds seems not to be recorded until the late 17th century, although breeding of plants for improved seed traits was continuing over the centuries. The originator of modern seed physiology, and a major founding contributor to plant physiology in general (and mineral nutrition and hydroponics in particular), was Julius von Sachs (1832-1897). He made

Distribution of Heavy Metals and Conjugating Ligands in Root

Cd-tolerant tobacco species (Nicotiana rustica) indicated greater labeled cadmium (109Cd) content in the roots than the leaves, the major part of which was stored in the distal part as a tolerance strategy (Bovet et al. 2006). In hyperaccumulator A. halleri roots exposed to 100 pM Cd and 500 pM Zn hydro-ponically, Zn and Cd accumulated in the cell walls of the rhizodermis (root epidermis), mainly due to precipitation of Zn Cd phosphates (Kupper et al. 2000). In roots, scanning electron microscope combined with energy dispersive spectrom-etry (SEM-EDS) confirmed that the highest Zn concentration was found in xylem parenchyma cells and epidermal cells, while for Cd, a gradient was observed with the highest Cd concentration in rhizodermal and cortex cells, followed by central cylinder. Light microscope results showed that Zn and Cd distributed mainly along the walls of epidermis, cortex, endodermis and some xylem parenchyma (Hu et al. 2009). Energy-dispersed X-ray (EDX) microanalysis...

Broad Spectrum Organic Matter Mediated Suppression

The role of organic matter in enhancing suppression of soilborne diseases caused by fungi, Oomycetes, bacteria and nematodes has been known for many years and there are now well-documented examples in many quite different agricultural systems. These include suppression of Pythium in Mexican fields following the application of large quantities of organic matter over many years (Lumsden et al. 1987) broad-spectrum control of Pythium, Phytophthora and Rhizoctonia in peat and compost-based soilless container media (Hoitink and Boehm 1999) the use of cover crops, organic amendments and mulches to suppress Phytophthora root rot of avocado in Australia (Broadbent and Baker 1974 Malajczuk 1983 You and Sivasithamparan 1994, 1995) suppression of the same disease with eucalyptus mulch in California, USA (Downer et al. 2001) the management of a fungal, bacterial and nematode-induced root disease complex of potato in Canada with chicken, swine and cattle manures (Conn and Lazarovits 1999...

State And Rate Variables

Water (or osmotic) potential values caused by the basic components of some widely used culture media in liquid form and nutrient solution for hydroponics. The values are converted for use at 25 C. The basic components consist of inorganic salts, vitamins and the other organic substances excluding sugar (Fujiwara and Kozai, 1995).

Heavy Metal Perception in a Microscale Environment A Model System Using High Doses of Pollutants

Abstract The characterization of the mechanisms of heavy metal detoxification has been undertaken through several experimental approaches, where high metal concentrations have been frequently used. A microscale hydroponic system was used to discriminate between the direct and indirect phytotoxic effects that may occur under heavy metal stress at short exposure times. Induction of oxidative stress and generation of stress signaling molecules are some of the physiological responses triggered soon after the exposure of plant cells to heavy metals, which might be part of stress perception mechanisms. The generation of reactive oxygen species, in particular H2O2, ethylene or jasmonate are envisaged as messengers in signaling pathways that may result ultimately in cell senescence and growth inhibition.

Concepts And Definitions

Narrowly defined, photoautotrophy is a nutritional type where living organisms grow without any additional exogenous organic components as nutrients. When defined in this narrow sense, media in photoautotrophic micropropagation should exclude all organic components. As in hydroponics, media for photoautotrophic culture consist exclusively of inorganic components. Vitamins, growth regulators, and gelling agents should not be added to the medium in photoautotrophic micropropagation. Instead of gelling agents, porous substances like vermiculite should be employed as supporting materials in photoautotrophic micropropagation. As will be discussed in later chapters, use of such supporting materials along with liquid nutrient solution under controlled environment has beneficial effects on the growth and development of in vitro plantlets.

Biochemical Essentiality of Elements in the Light of Enzymatic Reactions

In those early days (nineteenth and early twentieth century) there were just empirical studies on growth impediments brought about by lack of some purportedly essential element, without control and counterchecks. For this purpose, Sachs (around 1882) introduced hydroponic culture method, because the composition of aqueous or other solutions can be better and more easily controlled than that of the multiphase solid soil. Around 1900, biochemistry was

Aluminum Induced Inhibition of Root Growth

Root growth is a primary target for Al toxicity in plants. Maintenance of root elongation rate under Al stress is frequently used for Al tolerance screening purposes in hydroponics (Llugany et al. 1994 Ma et al. 2005 Narasihmamoorthy et al. 2007). Monitoring root elongation rates of maize varieties during the first minutes and hours upon exposure (Llugany et al. 1995) reveals various response patterns (Fig. 1) (1) The threshold of toxicity model, where a threshold time of 15-45 min and a threshold concentration (usually of a few mM) is required before Al-induced inhibition of elongation is detectable (2) the hormesis response, where a transient Al-induced stimulation of root elongation followed by inhibition is observed, and (3) the threshold oftolerance response, where a fast inhibition of elongation is followed by a recovery in the growth rate (Barcelo and Poschenrieder 2002).

Glutamine Synthetase Characteristics and localisation

In contrast to rice, most plants growing on well-aerated soils use NO3- as their main N source. In the root NO3- is partly reduced to NH4+ before being assimilated via GS GOGAT, but the proportion varies with plant species, plant age, and N availability (Tobin and Yamaya 2001). In roots of hydroponically grown barley seedlings, a GS1 (42 kD in subunit molecular mass) was constitutively detected in all root sections. Two additional polypeptides were detected in mature roots of NH4+-grown seedlings and one additional GS 1 in those grown on NO3- (Peat and Tobin 1996). Changes in GS1 polypeptides in response to NH4+ were also observed in barley roots (Mack 1995), although these differ slightly in molecular mass from the observation of Peat and Tobin (1996). Immunogold localisation studies indicated a higher concentration of GS1 in cortical parenchyma than in vascular stele cells (Peat and Tobin 1996). In these cell types the apparent concentration of GS1 was highest in N-deficient plants....

In Vitro Root Zone Environments And Their Effects On Growth And Development Of Plants

Key words Hydroponic, nutrient medium, osmotic potential, oxygen concentration, photoautotrophic micropropagation, root zone, supporting material, water potential. In photoautotrophic micropropagation, plantlets must be grown under appropriate environmental conditions that promote photosynthesis. These conditions should include considerations of not only the aerial (headspace) environment, such as CO2 concentration and photosynthetic photon flux, but also the root zone environment. While controlling the root zone environment is not easy, selection of supporting materials (i.e., replacing agar gel with porous supporting materials) that may create a better root zone environment (i.e., oxygen or nutrient availability) is relatively easy. Without sugar in the medium and with porous supporting materials and liquid medium, the system is more like a small hydroponic system, referred to as microponics (Hahn and Lee, 1996). Improvement of root zone environmental control in photoautotrophic...

Cultivation Systems to Achieve Optimal Growth Monitoring Situations

To enable a controlled variation of environmental parameters, growth monitoring systems have to be put in growth chambers or in controlled conditions of greenhouse facilities such as the Biosphere 2 Center (Walter and Lambrecht 2004) where the setup is protected from advert conditions like wind, rain or dew and where for example the effect of altered atmospheric CO2-conditions can be studied in detail. For root growth, image acquisitions have been performed either in agarose-filled Petri dishes (Beemster and Baskin 1998 Nagel et al. 2006) or in hydroponic cultivation systems using an inclined base plate (Walter et al. 2002b, 2003a). In both systems, roots are situated in a translucent medium allowing optical recording, are well supplied with nutrients and forced to grow in two dimensions only.

Genetic manipulation for the improvement of NUE

Amenziane et al. (2000) introduced the gdhA gene from Escherichia coli encoding a NADPH-GDH into tobacco plants and expressed under the control of 35S promoter. The introduced NADPH-GDH was apparently able to assimilate some of the excess NH4+, resulting from the increase in free amino acids, carbohydrates, and biomass production in the transgenic plants grown under controlled conditions or in the field. Transgenic wheat plants expressing the a-isoform of the Chlorella NADPH-GDH gene (aminating GDH) showed an increase in grain yield (Schmidt R., personal communication). Since the gene product contains a chloroplast-targeting transit peptide, the translated a-isoform GDH is localised in chloroplasts in the transgenic wheat. It has been shown that NH3 emission from barley leaves (Mattsson and Schjoerring 1996) and oil seed rape (Mattsson et al. 1997) occurs in plants grown hydroponically with 2 mM NH+ in the light, but not with NO3-. An inhibitor of GS increased the emission, while an...

One Possible Approach To Providing The Necessary Data To Test The Hypothesis

A range of concentrations of individual phenolic acids, mixtures of phenolic acids, or organic mixture including phenolic acids plus or minus nutrients and water plus or minus nutrients (control) could be added in solution form to soil surfaces in the field by direct applications or drip irrigation. However, surface applications of such solutions to field soil without some confinement are not advisable. The insertion of pipes into the soil (i.e., open ended soil cores) would be an effective way to eliminate horizontal movement and at the same time provide better phenolic acid distribution throughout the soil column. Such soil columns could also be brought to the laboratory, sterilized, and then used to determine soil sorption.13 Sufficient amounts or rates of solutions should be added for gravitational water to reach the bottom of the columns. Since soil columns will function as chromatographic columns, sufficient amounts and concentrations should also be used to obtain the desirable...

Ethylene and ABA crosscommunication and plant growth response to salt stress in tomato Solanum lycopersicum L

Ethylene (ET) is a signal molecule involved in the regulation of gene expression during adaptation to abiotic stresses. The relationship between ET and ABA production in vegetative tissues under abiotic stresses appears mostly controversial. In order to ascertain the interplay between ET and ABA in young plants (5th leaf stage), grown hydroponically in control (3 mS cm-1) and salt stress (10 mS cm-1) conditions, ET emission, ABA content and dry weight (DW) of roots, basal and apical leaves were measured in five different tomato genotypes cv Edkawi (EDK), salt tolerant cv Gimar (GIM), relatively salt sensitive and its near isogenic line for the nor gene (NOR) defective in ET synthesis the ABA mutants sitiens (SIT) and notabilis (NOT), both with different ABA biosynthetic capacity (8 vs 47 ).

The Poikilochlorophyll Desiccation Tolerance Strategy

The phenomenon of chlorophyll loss of PDT plant species during desiccation was first described by Vassiljev (1931) in Carex physodes from central Asia. The term poikilochlorophylly was coined by Hambler (1961), and it appears to be restricted to certain DT monocotyledonous plants (Hambler 1961 Bewley 1979 Bewley and Krochko 1982 Gaff 1977, 1989 Gaff and Hallam 1974 Hetherington and Smillie 1982a). The PDT strategy evolved in plants that are anatomically complex and include the largest in size of all DT species. This can be seen as an evolutionarily different and probably youngest strategy of desiccation tolerance. It is based on the dismantling of internal chloroplast structures by an ordered decon-struction process during drying and its resynthesis upon rehydration by an ordered reconstruction process. These processes can thus be thought of as not only being superimposed on an existing cellular protection mechanism of vegetative desiccation tolerance (Oliver et al. 2000), but as a...

Cell Wall Binding and Vacuole Sequestration

Hydroponically, Zn and Cd were accumulated in the cell wall of the rhizosphere as Zn Cd phosphates (Kupper et al. 2000). Cell wall binding can prevent Cd from being transported across the plasma membrane. This delay in transmembrane uptake may represent an important factor in the defense against Cd poisoning in T. caerulescens, allowing time for activation of intracellular mechanisms for heavy metal detoxification (Nedelkoska and Doran 2000).

Overexpression Of Mts As A Means To Increase Cadmium Tolerance

Plants overexpressing mammalian MTs were reported to be unaffected by concentrations of 100 to 200 M cadmium, but growth of N. tabacum control plants was severely inhibited at external cadmium concentrations of 10 M 77 . Transformants of Brassica oleracea expressing the yeast metallothionein gene CUP1 tolerated 400 M cadmium however, wild-type plants were unable to grow at concentrations above 25 M cadmium in a hydroponic medium. Transformants grown at 50 M cadmium accumulated 10 to 70 higher concentrations of cadmium in their upper leaves than did nontransformed plants grown at 25 M cadmium. This indicates that the enhanced tolerance observed in the transgenic plants was unlikely to be a consequence of excluding cadmium from the leaves.

Irrigation Scheduling

In the soybean, flood irrigation is a common practice in flat-bed-sown crop. However, where the crop has been sown on raised beds, furrow irrigation is applied. Some water-saving high-tech irrigation techniques such as sprinkler and drip irrigation are either not used or very rarely used in soybean. However, the choice of irrigation method is also determined by factors such as the source of irrigation, surface topography and soil texture. Furrow- and flood-irrigated soybean crops show better growth, seed yields and net returns than non-irrigated crops, and both irrigation systems are equally good in all of these parameters (Table 9.2). Drip irrigation not only uses less water than sprinkler irrigation but also maintains a higher soil temperature, leading to a higher emergence rate and enhanced seedling growth (Wang et al., 2000). Surface and subsurface drip irrigation systems can be used. However, in the case of subsurface drip irrigation, at lower depth a high moisture content with...

Pathways for Water and Solutes and Composite Transport

Water, because of the low permeability of membranes to solutes such as nutrient ions. Water, on the other hand, moves more rapidly by several orders of magnitude across membranes (in part, due to the existence of AQPs). In principle, the cell-to-cell or protoplastic component has to be split up into a transcellular (across membranes) and a symplastic (across plasmodesmata) component. However, to date, the latter two components cannot be separated experimentally and are, therefore, summarized as a cell-to-cell component. The cell-to-cell component can be determined from measurements with the cell pressure probe. These results have been compared with measurements at the root level, which allowed to judge about pathways, at least semiquantitatively. There is, to date, no technique to measure the contribution of the apoplastic water flow across the root cylinder or in other tissue. However, Zhu and Steudle (1991) compared hydraulic conductivities at the level of cortical cells of young...

Methodology of Assessments

In general, field trials are used, involving many species. In Italy, isozyme studies in combination with field trials are used for Quercus L., Juglans L. and Prunus avium L. Frost tolerance of Acerplatanoides L. and Pinus halepensis Mill. is tested by studying electrolyte leakage after freeze testing plant material. Hydroponics was used to test drought resistance of this species. Iceland reported freeze testing of Picea sitchensis (Bong.) Carr. and Abies lasiocarpa (Hook.) Nutt. Surveys, monitoring and in situ trials are common methods of testing the general performance of trees in the urban environment (UK, Germany, The Netherlands, Greece), salt resistance (UK, Iceland), resistance to photochemicals (Greece), stress resistance (Finland, Greece) rooting ability (Spain) and shape of the crown (Sweden). The UK and Belgium are using hydroponics to test the tolerance of salt and heavy metals in Salix clones. In Austria, pot experiments are used to screen the tolerance of de-icing salts...

Clip to close the vessel

And or plants during the rooting and acclimatization stages. This was an aseptic micro-hydroponic system with a nutrient solution control system. Roche et al. (1996) developed a commercial-scale photoautotrophic micropropagation for potato micro-plants in which 100 nodal explants were cultured under natural ventilation in a stainless steel tray containing a block of polyurethane foam (85 x 300 x 25 mm) and enclosed with a polyethylene sleeve.

Methodology And Strategy

The experimental design of most proteomics studies includes three steps that contain (i) a sample preparation and (ii) 1D or 2D separation by electrophoresis or chromatography, followed by (iii) MS analysis of the separated proteins. While the last two steps usually involve standard techniques, the first step does not. Any sample preparation starts with the choice of the plant material that is critical for the outcome of a proteome study and its reproducibility. The majority of studies used soil-grown Arabidopsis plants. However, plants grown hydroponically or on plates were also used. The age of the plants varied from 3 to 4 up to 7 weeks. With respect to light and illumination times, the variations are somewhat smaller. Normally the light intensity was 100-200 mol photons m-2 s-1 with 150 mol photons m-2 s-1 in most cases illumination times were between 8 and 14 h. So far no studies have been conducted on how these parameters affect the chloroplast proteome. The broad range of...

Nutrients and environmental quality

When growers strive for maximum production, the use of large amounts of fertilizer can result in nutrient losses, especially nitrate losses, in drainage water. A recent study of nitrate leaching in pineapple (Reinhart, 2000) showed that the loss of nitrate below a depth of 30 cm was greatest where large amounts of N (more than 300 kg ha-1 applied to a soil with high residual nitrogen) in inorganic fertilizer were applied prior to planting. Losses were negligible where manure was used in lieu of inorganic fertilizer (Reinhart, 2000). Foliar fertilization with over 700 kg N ha-1 did not increase leaching losses. Chemical losses through runoff and soil loss may also be significant when pineapple is cultivated on ridges on slopes without soil cover. They reached 63 kg N ha-1 year-1, 44 kg K ha-1 year-1 and 56 kg Ca ha-1 year-1 in an experiment on volcanic soils in Martinique (Khamsouk, 2001). Nitrogen losses due to leaching, runoff and erosion may be an important problem, especially in...

Deficiency and Toxicity Symptoms

When some element is deficient or present in such high concentration as to be toxic, plants often have symptoms somewhat characteristic of the particular condition afflicting them. For example, yellowing of leaves, or chlorosis, often indicates a deficiency of nitrogen. Nevertheless, visual identification of deficiencies or toxicities is not a reliable procedure. For example, sulfur deficiency may result in symptoms very similar to those of nitrogen deficiency. Therefore even experts check their visual impression by analyzing the tissue to find out whether its content of the suspected element is in fact below the value deemed adequate for that particular crop or present in excess. Often, such unrelated conditions as diseases caused by fungi or bacteria may result in the development of symptoms that mimic those of nutrient disorders. see also Biogeochemical Cycles Fertilizer Halo-phytes Hydroponics Nitrogen Fixation Soil, Chemistry of.

Release of 14Cphytosiderophores by barley roots

It has been reported that PS release occurs for 3-4 hours after an increase of the temperature, either in the growth chamber or under natural conditions (Takagi, 1993). In order to confirm the time for PS release and to know the absorption rate of PS or PS-Fe3+ in the roots, experiments were conducted using barley grown hydroponically by K. Itoh in Iwate University (personal communication).

Lead Acquisition And Transport

Thus, only a careful consideration of chelate application, taking into account factors like soil type and its total Pb content, can enhance the efficacy of a phytoextraction strategy. EDTA has been shown not only to enhance Pb desorption from the soil components to the soil solution but also to increase its transport into the xylem and its translocation from roots to shoots 7,30-32 . Vassil et al. 32 demonstrated that Pb accumulation in shoots is correlated with the formation of Pb-EDTA in the hydroponic solution and that Pb-EDTA is the major form of Pb taken up and translocated by the plant via xylem stream. The physiological basis of the uptake of Pb-EDTA and, particularly, the possibility of this large molecule to cross the cell membrane are unknown. However, using extended x-ray absorption fine structure spectroscopy, Sarret et al. 16 confirmed the presence of a substantial amount of Pb-EDTA in Phaseolus vulgaris leaves, when this plant was grown in a solution of Pb-EDTA.

Of phytosiderophores and iron in xylem sap of barley fed with iron III

More data on the relationship between the concentrations of PS and Fe in the xylem sap are necessary to discuss the role of PS on Fe translocation to the shoot in grasses. A feeding experiment with Fe3+ was conducted for barley grown hydroponically under -Fe condition. The time course for the changes in the concentrations of PS and Fe was observed after the plants were fed with FeCl3 (30 M) at 13 00. Eighteen plants of barley were decapitated at 3 hour intervals and xylem sap was collected for 3 hours. The change of the concentration of Fe or PS in xylem sap was monitored after the addition of Fe3+.

Concentration of iron in xylem sap of barley fed with ironIII and chelators

Metal concentrations in xylem sap collected from barley grown hydroponically with different concentrations of EDTA-Fe (0, 1, 10, 100 M). Figure 14-7. Metal concentrations in xylem sap collected from barley grown hydroponically with different concentrations of EDTA-Fe (0, 1, 10, 100 M). As a follow-up research, an experiment was conducted to examine whether PS could enhance Fe concentration in xylem sap more than other Fe chelators, when fed to the roots together with Fe3+. Roots of barley plants grown hydroponically under -Fe conditions were supplied with FeCl3 (30 M) and equimolar amounts of other Fe compounds, such as mugineic acid (PS), deferri-ferrioxamine B (FOB) (a microbial chelator) (van der Helm et al., 1987), EDTA, citrate, and malate from 13 00 to 16 00 p.m., when PS are not released from the roots. At 16 00 p.m., the plants were decapitated and xylem sap was collected for 3 hours.

Experimental methods

The methods used in these experiments were described in Kawai et al. (2001) and Alam et al. (2001a). Barley plants were grown hydroponically in bunches in a greenhouse (Kawai et al., 1988b). Plants were decapitated at about 2 cm above the roots with a stainless steel razor. Xylem sap extruding from the top of the stunts was collected by a capillary tube and kept in a test tube. After collection of the xylem sap, the weight and density of the liquid was measured. The volume of xylem sap was calculated based on weight and density. The xylem sap was stored under -20oC until analysis.

Whole Plant Problems

Seedlings fell over stems girdled or rotted at soil line. Cause Damping-off. This disease is caused by soil-dwelling fungi. To prevent it, disinfect reused poLs and flaLs before filling them with fresh seed-starting mix. To disinfect, dip them in a 10 percent bleach solution (1 part bleach to 9 parts water) and let them air-dry. Sow seed thinly to allow for air movement around seedlings. Cover seed with a thin layer of soilless mix or vermiculite. Water only enough to keep soil moist, not soggy.

Iron localization in the frd3 mutant

One of the most striking phenotypes of the frd3 mutant is its alterations in iron homeostasis. Examination of divalent cation levels in the leaves of the frd3 mutant reveals that metal levels are highly growth-condition dependent. If the frd3 mutant is grown in nutrient media, either hydro-ponically or in agar plates, conditions where iron is plentiful and highly available, it accumulates higher levels of iron in its leaves than does wild type (Delhaize, 1996 Rogers and Guerinot, 2002). However, if frd3 is grown on soil where iron is less available, its leaves contain approximately 10 less iron than wild type (Lahner et al., 2003). Intracellular iron levels in the frd3 mutant are approximately half of wild type levels, as shown by elemental analysis of protoplasts isolated from frd3 mutant and wild-type leaf tissues (Green and Rogers, 2004). Additionally, frd3 leaves contain much lower levels of ferritin, an iron storage protein that only accumulates under conditions of excess iron...

Stimulus Produced by Stress

Fig. 17.1 Flowering of grafted plants under poor-nutrition stress conditions in Pharbitis nil. Two varieties of P. nil were grafted in the combinations as shown (scion stock) and grown hydroponically in tap water. The nongrafted control plants were grown on vermicu-lite and fed with tap water. Plants were grown under

Wholeplant Water Availability And Growth Can Also Be Limited By Colloid Stress

The possibility that the availability of water to higher plants may also be limited by interactions with environmental colloids is generally overlooked. This section briefly introduces recent laboratory findings which indicated the existence of 'plant colloid stress'. Asli and Neumann (2009) investigated the possibility that colloidal suspensions of inorganic nano-particulate materials of industrial or natural origin, that can be present in soil solutions, could interfere with rhizosphere water transport. They found that external colloidal suspensions of either naturally derived bentonite clay particles or industrially produced TiO2 nanoparticles (30 nm diameter) at 1 gL 1 could significantly reduce water transport through the intact epidermal surfaces of maize primary roots by up to 40 . Moreover, similar additions to the hydroponic solution surrounding the roots of whole-maize seedlings rapidly inhibited leaf growth and transpiration. A subsequent report showed that colloidal...

Technical Challenges To Commercial Production

Propagating M. x giganteus using rhizome divisions entails separating a rhizome mass into small pieces for replanting. This can be done with potted plants growing in greenhouses and can also be conducted using field-grown plants. University of Illinois experience has determined that the potted M. x giganteus can often be divided every 4-8 weeks (Pyter et al., 2009) when grown in greenhouses under 12 h per day artificial light during winter using 10 cm square pots and an artificial, soil-less potting mix.

NO emission from nitrate reductase

Typical pattern of NO-emission from detached tobacco leaves. The upper curve shows data from nitrate-fed plants. NO emission is low in the dark (grey or black bars on top of the figure), up to 10-fold higher in the light and increases transiently after light off. This is due to a transient overshoot of nitrate reductase leading to some nitrite accumulation, which stops after NR has been down regulated in the dark, requiring 5 -15 min. In contrast to NR, nitrite reduction stops immediately after light off. NO emission in the dark is drastically stimulated under anoxia, (black bar) because NR is activated, NiR does not work, leading to a strong accumulation of nitrite. Probably, the absence of reactive oxygen species under anoxia also contributes to the high NO-emission under dark-anoxic conditions (compare to Figure 5). Also shown (lower curve with open symbols) is the complete absence of NO-emission from leaves of ammonium-grown hydroponic tobacco plants, which contain no...

Mineral Nutrition and the Transport of Water Minerals and Sugars

It had long been known that water, along with dissolved minerals, enters a plant through its roots. Sachs demonstrated that plants do not require soil and can be grown in an entirely liquid medium as long as the medium contains the minerals required for survival. This technique of hydroponics facilitated studies of the mechanisms for mineral uptake by the roots.

Concentrations in Plant Parts

Another point is the distribution of metals inside the plants metal concentration in the plant varies with the organ and the age of this organ 31,61-63 . Figure 30.5 shows Cd distribution within leaves of S. viminalis grown in hydroponics Cd is located at the edges and tips of the younger leaves but is mostly at the base of the older leaves 64 . In addition, concentration varies with the species 65 , the metal 66,67 , and the soil characteristics. In general, Zn, Cd, and Ni tend to accumulate in shoots, whereas Cu and Pb remain in roots. This has consequences for the time of the harvest and the parts to be harvested.

Leaf and Whole Plant Problems

Seedlings foil over stems girdled or rotted at soil line. Cause Damping-off. Disinfect reused pots and flats by dipping them in a 10 percent bleach solution and letting them air-dry before filling them with fresh seed-starting mix. Sow seeds thinly to allow for air movement around seedlings. Cover seed with a thin layer of soilless mix or vermiculite. Water only enough to keep soil moist, not soggy. Thin seedlings and spray with compost tea as soon as First true leaves open to help prevent the problem.

Modeling For Yield Estimation

The conceptual models, which do not neglect solute reactions in the root zone, the surface evaporation and influence of immobile wetted pore space can accurately predict the leaching requirements (Lr) for crops from salinity of irrigation water and the crop salt tolerance threshold (Alsaeedi and Elprince, 1999). The application of a sprinkler (such is triple line source sprinkler system) and a drip irrigation system was successfully used in screening for salinity tolerance in barley (Isla et al., 1997). Several other models dealing with estimation of specific parameters of soil salinity, two- and three-dimensional equilibrium solute transport, field-scale spatial salinity patterns, etc., have been proposed during the last twenty years by USDA (USDA Salinity Laboratory, Among them, the newest model (WATSUIT), developed in 2001, predicts the salinity, sodicity and the toxic solute concentrations of the soil water within a simulated crop root zone. This model allows an evaluation of crop...

Considerations About The Optimum Nutrient Solution Temperature

Nutrient solution temperatures may reach injuriously high levels during summers, or damaging low levels in winters, which strongly influence growth and survival of the whole plant. This parameter not only depends on solar radiation and aerial temperature but also on the characteristics of the system. In general, soilless systems are exposed to larger daily variations in root temperatures than soil systems (Kafkafi, 2001) but possibilities for accurate control of root temperatures are more easily carried out in soilless cultures than in soils systems (Olympios, 1999), through cooling or heating systems. However, sometimes an excessive energy input is spent to protect the crop from incorrectly established temperature ranges. In order to optimize the use of energy in greenhouse production, it is necessary to know the range of nutrient solution temperatures, specific for each crop cultivar (Kafkafi, 2001), which permits plant growth and promotes high yields. In general terms, root zone...

Two Classes Of Feedback Agents

The chemical nature of the agents responsible for the negative feedback of plant N fluxes is not completely resolved, although it is essential for these agents, as well as the mechanisms by which they act, to be identified, if the prospect of altering N influx (or net N acquisition) is to be achieved. Therefore, this subject deserves further attention here. Feedback agents are likely to fall into two categories, the transported substrates themselves, or the N metabolites produced from these substrates (chapters 1 and 2). Correlative evidence that NH4+ accumulation in the cytosol of root cells feeds back negatively on NH4+ influx into these cells was found by Wang et al. (1993a), who grew rice plants hydroponically, in complete nutrient solutions with three NH+ regimes (2, 100, and 1000 pM). As shown in Figure 2, the influx of NH4+ at a given external concentration declined with increasing steady-state concentration of NH4+ applied during growth the cytosolic pool size of NH4+ was...

Concluding Remarks

Current advanced greenhouse technology for plant propagation and transplant production has been well developed for a large-scale production. Thus, for the development of a large-scale photoautotrophic micropropagation and transplant production system, technologies of plug seedling production, hydroponic culture, greenhouse environment control, and greenhouse crop management can be applied with careful consideration of disease protection. The current photoautotrophic micropropagation system can be improved further for a larger scale production by incorporating recent technologies of computers, robotics, energy-saving, recycling, environmental conservation, ecological engineering, etc. At the same time, photoautotrophic micropropagation is suitable also for a small-scaled operation.

Anatomy Refrences Of Aloevera

Carbohydrate Research, 60, 345-351. Pierce, R.F. (1983) Comparison between the nutritional contents of the aloe gel from conventionally and hydroponically grown plants. ERDE International, 1, 37-38. Radjabi, F., Amar, C. and Vilkas, E. (1983) Structural studies of the glucomannan from Aloe

Approaches for Developing Salt Tolerant Crop Plants

Pepper Dihaploid 2012

The success of the crop-breeding program largely depends on the availability of natural genetic variation among the germplasm resources. Large number of cultivated and wild germplasm in major crops, preserved in the Consultative Group on International Agricultural Research (CGIAR) institutions and national centers, provide unique resources for systematic screening for discovery of novel variability to improve adaptation of crop plants in saline environments. Particularly, the wild relatives, land races, and traditional culti-vars are the potential reservoirs of novel alleles to improve abiotic stress tolerance. Accurate pheno-typing procedures are critical for identifying useful germplasm for crop improvement program as well as for deciphering the genetic basis of the mechanisms associated with salinity tolerance. Several parameters for salinity tolerance are studied by growing the germplasm in a variety of culture techniques such as hydroponics, pot culture, and field screening....

Occurrence Of Iron Deficiency In Field Crops

Wheat and oat are tolerant to Fe deficiency, even when grown in soils where Fe deficiency may be a problem with other crops (Table 2-1). However, both oat and wheat show significant susceptibility to Fe deficiency under animal grazing practices, a major management scheme used on much of the wheat acreage in Southern Plains region of the U.S and in the oat acreage in South Texas. Grazing semi-dwarf winter wheat during the vegetative stage is common in the Southern Plains region of the U.S. This practice can reduce grain yields, but allows for economic gains through its use as forage (Winter and Thompson, 1990). Factors such as reduced leaf area and seed weight and increased winterkill contribute to lower grain yield in grazing systems, but in some instances, the grazing has also triggered Fe-deficiency chlorosis in the vegetative regrowth for wheat cultivars that do not normally exhibit chlorosis when not grazed (Berg et al., 1993). Most of the oat grown in south Texas is grazed and...

Determination of water requirements and plant moisture status

A, Drip-irrigation system used in dry areas in Hawaii B, self-propelled overhead irrigator used where drip irrigation is unavailable. Fig. 6.16. A, Drip-irrigation system used in dry areas in Hawaii B, self-propelled overhead irrigator used where drip irrigation is unavailable. pineapple shows to drip irrigation (Fig. 6.16A).

Other Mediterranean Fruit Species

The water relations of field grown pomegranate trees grown under different drip irrigation regimes were recently investigated by Intrigliolo et al. (2011). These authors observed that during spring and autumn, midday SWP was not significantly different between irrigation treatments while there were considerable differences in leaf photosynthesis and stomatal conductance, suggesting a near-isohydric behaviour of pomegranate trees. This means that plants control gas exchange such that daytime water content is almost unaffected by soil water deficits, and that other mechanisms (e.g., ABA production and signaling) can be responsible for the regulation of plant water status. There is little knowledge about the response of pomegranate to drought, and in general to abiotic stresses. In one of the few researches, Bhantana and Lazarovitch (2010) studied the evapotranspiration, crop coefficient and growth of two young pomegranate varieties under salt stress, confirming that this species...

Utilization of microbial siderophores by plants

Numerous studies have investigated the ability of plants to use microbial siderophores as iron sources for growth (Table 8-2), and have examined the possible mechanisms by which plants might obtain iron from these compounds, either by exchange with phytosiderophores or by the iron reductase that is expressed by Strategy I plants. However, these experiments have been controversial for several reasons. Since siderophores are labile and are subject to degradation after their addition to soil, almost all of the studies on plant use of microbial siderophores relied on hydroponic experiments in which radiolabeled siderophores were added to nutrient solutions at known concentrations generally ranging from 1 to 100 .M. Root Iron uptake from siderophores by Strategy I plants has been examined for the hydroxamate siderophores ferrichrome, ferrioxamine B, rhodotorulic acid, and the mixed ligand siderophore pseudobactin produced by Pseudomonas spp. Other siderophores that have been studied and...

Nodule Cultivation And Harvesting

A primary need for starting a N2-fixing organ proteomics is the availability of the nodule sample, the starting material, in sufficient amounts. Methodologies adopted may differ depending on the type of legume and experimentation. Sometimes, legumes are grown in the soil (field plots or pots) where nodulation starts due to the bacteria present in the soil. Pre-inoculation of seeds that help in immediate infection of roots as they emerge is also practised. The species of symbiotic N2-fixing bacteria is isolated from nodule bacteroids and cultured in vitro or in fermenter. A variety of nutrient culture media such as diluted sugarcane molasses and modified Hoagland nutrient solution are used. Growth of bacteria is monitored spectrophotometrically. The cultured media serve as master culture'' which is used to inoculate for nodule induction in the root. These days, legumes are very often grown in hydroponics and a part of master bacterial culture is added to the hydroponic culture. These...

Review Of Heat And Light Stress In Medicinal Plants

Horvath E, Janda T, Szalai G, Paldi E (2002) In vitro salicylic acid inhibition of catalase activity in maize differences between the isozymes and a possible role in the induction of chilling tolerance. Plant Sci 163 1129-1135 Horvath E, Pal M, Szalai G, Paldi E, Janda T (2007b) Exogenous 4-hydroxybenzoic acid and salicylic acid modulate the effect of short-term drought and freezing stress on wheat plants. Biol Plant 51 480-487 Hua J, Grisafi P, Cheng SH, Fink GR (2001) Plant growth homeostasis is controlled by the Arabidopsis BON1 and BAP1 genes. Genes Dev 15 2263-2272 Iba K (2002) Acclimative response to temperature stress in higher plants approaches of gene engineering for temperature tolerance. Annu Rev Plant Biol 53 225-245 Ichimura K, Mizoguchi T, Yoshida R, Yuasa T, Shinozaki K (2000) Various abiotic stresses rapidly activate Arabidopsis MAP kinases ATMPK4 and ATMPK6. Plant J 24 655-665 Jambunathan N, Siani JM, McNellis TW (2001) A humidity-sensitive Arabidopsis copine mutant...

Mechanisms of Metal Tolerance in ECMF

Carbon obtained from the host would benefit more if it alleviates metal stress in its host tree, with other words, selection is likely to favour host protection by ECMF, especially in pioneer populations, where only one tree individual might be available as carbon source. However, there is some experimental evidence that the most resistant ECMF species is not necessarily the most protective one (Jones and Hutchinson 1986). Godbold et al. (1998) concluded that only in a small number of experiments, amelioration of metal toxicity could be demonstrated, and that this was the case for specific metals and certain fungi only. The statement that amelioration of metal toxicity is highly species, strain and metal specific is still valid. However, it has to be considered that many earlier experiments with negative results had used ECMF from unpolluted sites, while amelioration of metal toxicity under experimental conditions had been recorded most often when fungi from metalliferous were used....

Factors Affecting Water Use and Wateruse Efficiency in Soybean

Alternate furrow irrigation can further enhance WUE by using less water. In sprinkler and drip irrigation systems, WUE is further improved as water losses are checked to a large extent. Sprinkler and drip irrigation systems are normally used in fields with uneven surfaces and in areas where there are severe water shortages. With surface and subsurface drip irrigation systems, the latter has higher irrigation WUE due to lower evaporation loss (Bhattarai et al., 2008). However, the initial high costs involved in establishing these systems is a major factor in these systems remaining unpopular among farmers.

Germination Stimulants 421 Strigolactones

Strigol, the first germination-stimulating compound to be positively identified (Cook et al. 1966, 1972), was initially purified from hydroponically grown roots of cotton plants a false host of Striga that stimulates seed germination but does not support development of the parasite and was found to stimulate seed of S. lutea, eliciting 50 germination at concentrations as low as 10-5 ppm in water. Subsequently, a structural analog of strigol, sorgolactone, was isolated from sorghum, a true host of Striga (Hauck et al. 1992), while strigol itself was found to be present in the true hosts maize and millet (Siame et al. 1993). A chemically similar compound, alectrol, was identified from cowpea (M ller et al. 1992) . Later, alectrol and another naturally occurring strigolactone, orabanchol, were found to serve as stimulants for Orabanche seed germination in response to root exudates of red clover. Lynn and colleagues previously questioned whether strigolactones were plant-derived compounds...

Inoculation of plants with siderophore producing microorganisms

The ability of plants to utilize microbial siderophores as iron sources for growth is highly controversial and has been investigated using a variety of experimental approaches using hydroponic and soil culture. Although there are considerable differences in the quantities of siderophores that are produced by various strains and species of bacteria, there is no evidence to date that inoculation with bacterial strains that produce high quantities of siderophores is beneficial to plant iron nutrition. Experiments in hydroponic culture show that inoculation of Strategy II plants with soil microorganisms can be detrimental to plants by causing rapid degradation of phytosiderophores which are not replaced by concomitant production of microbial siderophores at a commensurate level that can support plant growth (Duijff et al., 1994 Walter et al., 1994). This rapid degradation of phytosiderophores in hydroponics is thought to be an artifact of hydroponic culture where the microorganisms have...

Dissolution Of Soil Native Iron By Chelating Agents

When the Fe-chelate releases Fe to the plant, the chelating agent may dissolve native Fe (Figure 5-1), which can be then transported to the plant (Chen and Barak, 1982 Lindsay, 1995 Lucena, 2003). However, the importance of this dissolution process in plant Fe nutrition is not well known. Schwertmann (1991) reviewed the knowledge on the processes of dissolution of Fe oxides, indicating that most of the studies concerning chelating agents have been done for the estimation of the plant-available Fe. The chelating agent may dissolve native Fe present in the solid phases. This is a kinetically controlled process that depends on the chelating agent (Stone, 1977), the nature of the solid phase (Schwertmann 1991 Perez-Sanz and Lucena 1995 Nowack and Sigg, 1997) and the soil conditions. The rate of dissolution may be the limiting factor for the whole process. It has been hypothesized that kinetics, rather than equilibrium, probably controls the speciation of low stability complexes (such as...

Variety selection and screening for tolerance

Jessen et al. (1988) noted that early expression of Fe deficiency response appeared to be correlated to Fe efficiency. This observation is important in the theory behind screening by Fe reduction measurement. An Fe-reduction based screening approach exploits the early Fe deficiency response of resistant plants by measuring Fe reduction early in the plant life cycle and correlating this value to chlorosis resistance. Jolley et al. (1992) found that chlorosis susceptibility relates closely to the magnitude and timing of Fe reduction by soybean roots. The quantity of Fe reduced over days four through eight (after initiation of Fe deficiency treatments) correlated negatively with field chlorosis scores with r -0.86. Measurement over longer lengths of time did not improve correlation, demonstrating that accurate assessment could be made in a relatively short time period. The accuracy of the Fe reduction screening test has been further improved by buffering nutrient solutions with CaCO3 and...

Electrical Conductivity And pH In The Nutrient Solution

The ideal EC range for soilless crops is between 1.5 and 2.5dS m. However, the effect of salinity on crops is specific on the species and cultivar (Greenway and Munns, 1980). In general, EC > 2.5 dS m may lead to salinity In some cases, though, it may be advisable to use a high EC to improve the quality of the produce. For example, the quality of flavouring and health-promoting compounds in hydroponically grown tomatoes improves with increasing electrical conductivity in the nutrient solution (De Pascale et al., 2003 Krauss et al., 2007). On the other hand, pH is a measure of the acidity or basicity of a solution and determines the availability of essential elements to plants. pH is an essential parameter to control in soil and soilless system, but in the latter, its correction should be done on daily basis because of the lower buffering capacity of soilless systems (Urrestarazu, 2004). In fertigation, pH should be such that it does not damage plant roots and allows all essential...

Signaling Events During CAM Modulation by Salinity

Whereas endogenous ABA accumulation is commonly observed during the drought-induced C3-CAM transition (Freschi et al. 2010a Taybi and Cushman 2002 Taybi et al. 1995), much less clear is the relationship between this phytohor-mone and the CAM induction by salt stress (Taybi et al. 2002 Thomas et al. 1992). Working with hydroponically grown M. crystallinum plants, Thomas et al. (1992) observed that increases of about tenfold in the leaf ABA content coincided with the rise in PEPC enzyme triggered after 30 h of salt stress treatment. In contrast, when detached leaves of this same species were exposed to only 9 h of salt stress, no significant changes in endogenous ABA were observed, even though a marked increase in Ppcl transcript abundance could be detected (Taybi and Cushman 2002). Moreover, inhibition of ABA biosynthesis did not prevent the induction of PEPC expression by salt stress (Taybi and Cushman 2002 Thomas et al. 1992), indicating that ABA might not be required for the...

Factors That Regulate Nutrient Uptake By The Plant

Second theory plants regulate their uptake according to their demand This theory suggests an active role of the plant in nutrient uptake and establishes that plants regulate their uptake according to their demand. If this statement is true, one would have to predict plant nutrient absorption, that is plant demand, to design the optimum nutrient solution. So next the question would be What does plant demand depend on In order to answer this question, many authors have developed mechanistic or empirical models that try to predict different crop nutrients uptake from several factors, with or without including nutrient solution concentration (Brun and Chazelle, 1996 Klaring and Cierpinski, 1998 Klaring et al., 1997 Le Bot et al., 1998b Mankin and Fynn, 1996 Papadopoulos and Liburdi, 1989 Pardossi et al., 2005 Zerche, 2000). Plant nutrient uptake depends on the root surface area and on the uptake properties of this surface. Due to the importance of root surface area on plant nutrient...

Content of phytosiderophores amino acids organic acids and metals

It was tentatively concluded by TLC and HPLC analysis that PS do exist in xylem sap of -Fe or +Fe barley plants (Kawai et al., 2001). At present, data are available for the composition of PS, amino acids, organic acids, and metal essential elements in xylem sap of barley plants (Alam et al., 2001b). Xylem sap was collected from decapitated roots of plants grown hydroponically under -Fe or +Fe conditions. The xylem sap concentrations of macro- or micro-nutrients in -Fe or +Fe barley plants grown hydroponically are shown in Figure 14-5. The -Fe treatment did not affect the concentrations of metal macronutrients such as K, Ca, and Mg. On the other hand, the concentrations of metal micronutrients were affected by -Fe treatment. The Fe concentration decreased, while Mn, Zn, and Cu increased considerably by -Fe treatment. Figure 14-6. Concentration of organic acids in xylem sap of Fe-sufficient or Fe-deficient barley grown hydroponically. Figure 14-6. Concentration of organic acids in xylem...

Auxin and Essential Metals

Different tissues exhibit different sensitivity to metal stress. For example, in poplar stem radial growth declined already when the plants were grown in the presence of 1 pM Cu in hydroponic nutrient solutions, whereas elongation growth and photosynthesis declined only when the plants were exposed to 50-fold higher Cu concentrations (Elobeid and Polle 2010). It was suspected that sub-toxic concentrations might already affect the phytohormone balance and thereby influence growth. In Helianthus annuus elongation growth of roots was more strongly reduced in the presence of excess Cu (80 pM) than that of shoots (Ouzounidou and Ilias 2005). Application of auxin diminished the negative influence of excess Cu and improved the water use efficiency of the plants. Thus, auxin application alleviated The involvement of Mn with auxin physiology is known for a long time. Already in the 1960s in vitro studies showed that Mn stimulated auxin degradation involving auxin oxidase activities (e.g.,...

Nitrate Uptake Where And How Localisation of NO3 uptake in plant roots

The second question about the localisation of NO3- uptake in the root - does it occur over the entire root surface or only in specific regions of the root - has been sporadically debated. Essentially two methodologies, based upon the localised supply of 15NO3- (Lazof et al. 1992, Nazoa et al. 2003) and the utilisation of NO3--selective microelectrodes (Henriksen et al. 1990, 1992, Colmer and Bloom 1998, Bertrand et al. 2000) respectively, have been used to measure the general pattern of NO3- uptake along roots. Overall, the experimental evidence obtained with both techniques shows that NO3- uptake occurs at all locations of the root surface, from the tip to the base, although a peak is usually measured in a sub-apical region. Due to the small size of this zone compared to the whole root surface in an actively growing plant, the older regions of the root should contribute to the total acquisition of NO3- for an important part. This conclusion is derived from data obtained with young...

Phytohormone Signaling Pathways

Production possibly via an augmentation of ACC synthase enzymatic activity in Arabidopsis plants (Arteca and Arteca 2007). Similarly, pea plants exposed to 50 mM Cd for 14 days accumulated a remarkable amount of ethylene in leaves (Rodriguez-Serrano et al. 2009), which would be part of the signaling process involved in the defence responses to heavy metals (Guo and Ecker 2004).We have concluded a transcriptomic analysis of the early responses of alfalfa seedlings to 3 mM Hg using the microscale hydroponic system. Our results support the idea that ethylene might be part of the signalling molecules that are induced by heavy metals, and we found that transcription factors responding to ethylene (such as ERF1) are up-regulated after just 3 h of treatment (Montero-Palmero et al., personal communication). Ethylene acts by the activation of the mitogen-activated protein kinase (MAPK) cascade (Guo and Ecker 2004), signal transduction process that is also activated by Cd and Cu (Yeh et al....

Water Uptake at Water Shortage Role of Apoplast and of Composite Transport

Zimmermann and Steudle (1998) compared the hydraulics of young roots of corn with and without an exodermis. When the seedlings were grown in hydroponics, they did not develop a continuous exodermis. But when grown in mist culture they did, which reduced the hydraulic conductivity by a factor of 3.6 at constant water permeability of root cells. Recently, the thicker roots of Iris germanica have been studied by Meyer et al. (2010). When exposed to air, these roots developed a continuous multiseriate exodermis, which was uniseriate, when roots were brought up in hydroponics. As for the young corn roots, the treatment caused substantial changes in the root hydraulics measured by combining the root pressure probe and the pressure chamber. When present, the multiseriate exodermis was limiting water flow (as for corn grown in mist culture).

Strategies For Enhanced Uptake Of Trace Elements To Facilitate Phytoextraction

Chelate-assisted phytoextraction in field conditions is likely to increase the risk of adverse environmental effects such as ground water pollution due to leaching of metal-laden seepage during extended periods after chelate application. Wenzel et al. 109 hypothesize that free protonated EDTA enters the roots, subsequently forming metal complexes that enhance metal transport to shoots. However, the study of Vassil et al. 110 was conducted in hydroponic conditions, whereas EDTA in soil is expected to form complexes with Ca and other metals. Greman et al. 111 reported ethylenediaminedisuccinate (EDDS) as a promising new chelate for enhanced, environmentally safe phytoextraction of Pb-contaminated soils. It caused only minor leaching of Pb and was significantly less toxic to plants and soil microbes. To avoid possible chelate-metal movement into ground water, the amount, time, and method of chelate application should be carefully controlled. Huttermann and coworkers applied cross-linked...

Biological or Physiological Role of Cd

Hyperaccumulator species of Cd may be ideal materials to test this hypothesis, because in recent years there is increasing evidence from biological and physiological studies at various levels to support a positive role of Cd in these exceptional species (Table 2, Fig. 1g). At the whole plant level, stimulation of biomass production by addition of Cd in substrates has been observed in most discovered Cd hyperaccumulators (Table 2). The stimulatory effects of Cd on plant growth can vary greatly, depending on the type (ecotype) of species, the growth time, and the substrate tested. For example, Liu et al. (2004) reported by far the greatest increase of approximately 300 of total biomass in Viola baoshanensis when treated hydroponically with 267 p.M Cd, whereas A. halleri showed trivial positive response even at relatively low Cd (5-15 p.M) in solution (Zhao et al. 2006). In S. alfredii, it is noticeable that while less stimulation (17-25 ) of shoot dry weight occurred at 12.5-100 p.M Cd...

Am Fungi And Plant Disease Control

AM fungi are rarely found in commercial nurseries due to the use of composted soil-free media, high rates of fertilizer application and regular application of fungicide drenches. The potential advantages of AM fungi in horticulture, agriculture, and forestry are not perceived by these industries as significant. This perception may be due in part to inadequate methods for large-scale inoculum production.

Chemical Constituents

5-hydroxyaloin A, characteristic of Cape aloe, is absent in Curacao aloe. However, studies carried out on plants grown hydroponically under carefully controlled conditions still show these variations for example, aloin content can vary as much as 80 from one plant to another in the same field. Aloes also contain other healing components such as analgesic and anti-inflammatory agents, (aloctins, cholesterol, campesterol, P-sitosterol, acemannan, salicylates, etc.), immunostimulant agents, (acemannan, lectin, etc.) and antiseptic agents (lupeol, salicylic acid, phenol, sulphur, etc.). The benefits of aloe are, however, due to synergism between compounds also, it is quite possible that other unidentified co-factors present in aloe may provide for the optimum effects generally encountered.

Considerations About The Optimum Oxygen Concentration In The Nutrient Solution

Oxygen is essential for the functioning of roots, hence, its deficiency is an important concern. Problems with oxygen supply may periodically appear in soil conditions after rains. Also, in soilless systems, water and nutrients are supplied continuously and these wet conditions limit diffusion of oxygen to the root system (Veen, 1988). Oxygen deficiency stress in plants is distinguished by three physiologically different states transient hypoxia (insufficient supply of oxygen), possible anoxia (complete lack of oxygen) and reoxygenation (Blokhina et al., 2003). An inadequate management of irrigation may lead to temporal hypoxia conditions caused by inadequate aeration in some parts of the root system (Morard and Silvestre, 1996). In contrast, anoxia is rare in soilless culture (Klaring and Zude, 2009 Morard and Silvestre, 1996). In order to avoid oxygen deficiency in the root environment, it is essential to provide the nutrient solution with enough O2. Possibilities for accurate...

Metal Tolerant Plants And Chelators Might Promote Phytoremediation Technology

Possible amendments for acidification include NH4-containing fertilizers, organic and inorganic acids, and elemental S. Trelease and Trelease 77 indicated that plant roots acidify hydroponic solutions in response to NH4 nutrition and cause solutions to become more alkaline in response to NO3 nutrition. Metal availability in the soil can be manipulated by the proper ratio of NO3 to NH4 used for plant fertilization by the effect of these N sources on soil pH, but no phytoremediation research has been conducted on this topic to date.

Complex Formation With Organic Acids

In one of the models for the transport of Zn into vacuole, it has been postulated that malic acid would bind Zn in the cytosol, thereby detoxifying it, and the Zn-malate complex would be transported over the tonoplast into the vacuole where it would dissociate 39 . After this, malate would be retransported into the cytosol. Vacuolar Zn would remain bound to stronger chelators, such as citrate, oxalate, etc., when present. Brune et al. 151 reported that barley mesophyll cell vacuoles contain appreciable concentration of phosphate (30 to > 100 mol m-3) malate (> 10 mol m-3) sulphate (> 4 mol m-3) citrate ( 1 mol m-3) and amino acids (> 10 mol m-3) when grown in hydroponic culture. They hypothesized that these organic and inorganic salts interact with the divalent cations, thereby buffering the vacuolar free Zn concentration to low values even in the presence of high Zn levels (292 mmol m-3) in the vacuolar space.

Banded preplant fertilizers

The precision placement of preplant fertilizers can ensure both vigorous rooting and the early uptake of N, P and K prior to the development of the leaf canopy. Banded fertilizer should be applied in sufficient amounts to enhance rooting and carry the young plants for 3-4 months, until the canopy is sufficiently developed to make foliar fertilizer applications efficient and effective. Placement is usually just below or adjacent to the plant line to allow the earliest interception by the developing roots. Plastic mulch can protect fertilizer from leaching or volatilization. However, water applied by drip irrigation can contribute to losses by leaching. Many types of fertilizers are available, such as urea, ammonium sulphate, potassium nitrate, superphosphate and treble superphosphate, ammonium phosphate, magnesium sulphate, muriate or sulphate of potash, and others. The choices should complement both the previously incorporated broadcast amendments and, where foliar fertilization is...

Early roothealth management

With the discovery of the soil fumigant 1,3-dichloropropene, 1,2-dichloro-propane, (DD mixture) pineapple nematodes were easily and economically controlled during the early stages of pineapple plant growth (Carter, 1943 Keetch, 1979 Johnson and Feldmesser, 1987 Caswell and Apt, 1989). Today, early nematode control is accomplished by clean fallow, preplant soil fumigation with dichloropropene at 224-336 l ha-1 (Fig. 9.17 ) and postplant application of an approved nematocide (e.g. fenamiphos and oxamyl) by broadcast sprays or drip irrigation (Fig. 9.18 Fig. 9.18. Postplant drip irrigation and application of postplant nematocides. Fig. 9.18. Postplant drip irrigation and application of postplant nematocides.

Measurement Of Plant Nutrient Uptake

This method allows a good accuracy of nutrient uptake over time (Klaring, 2001) and the results are comparable to those obtained by destructive long-term N measurements (Barak et al., 1996). However, a correct methodology should be applied to avoid errors in the measurements. Obtaining samples from the root environment is difficult, and samples of the drainage might not represent the composition of the nutrient solution surrounding the roots. In that case, a soilless system with a low inertia should be used (e.g. nutrient film technique and aeroponic system). Moreover, the system should avoid evaporation so that all volume losses can be attributed to water and nutrient uptake. Finally, this method is less accurate when nutrient solution concentration is elevated (Le Bot et al., 1998a) thus, diluted solutions are recommended.

Measurements of siderophore production in the rhizosphere

Using rapid growing annual plants in hydroponic cultures where siderophores are supplied at fixed concentrations as a potential iron source for plants. On the other hand, the importance of siderophore accumulation in rhizosphere of slow growing perennial plants, shrubs, and trees where fine roots persist for up to a year, and regrow year after year in the same macropores is another consideration that has largely been ignored. After initial reports indicating low concentrations of siderophores in soils even under conditions with high microbial activity, there was debate over whether the levels that were measured would be important for supply of iron to plants. As a basis of comparison, plants generally require 10 to 50 .M soluble iron when complexed either with siderophores or with synthetic iron chelators, when grown in hydroponics (Crowley et al., 1988). The low concentrations of siderophores that are detected in soils are not at concentrations that would be sufficient to support...

Considerations About The Optimum Water Supply

In soilless culture, an accurate and dynamic control of the water supply is needed to meet plant water requirements due to the low water holding capacity of the system (De Boodt and Verdonck, 1972). Optimum water supply should fulfil plant demand and also prevent salt accumulation in the substrate area surrounding the root. However, under conditions of high transpiration (e.g. at midday in summertime), supply of water may be often insufficient leading to temporal water stress in the plant. In order to avoid this, sometimes excess water is supplied. This results in excessive ion lixiviation within the root environment and loss of unabsorbed water, which should be avoided from an environmental standpoint because water is a scarce resource. For review about the environmental impact of irrigation see Stockle (2001). In order to carry out an effective management of irrigation, precise information of water status of the group substrate-plant-environment is needed. Different methods try to...

Practical Control System

The potential of AM fungi to enhance plant growth is well recognized but not exploited to the fullest extent. These organisms are rarely found in nurseries due to the use of composted soil-less media, high levels of fertilizer and regular application of fungicide drenches. The potential advantages of AM fungi in horticulture, agriculture, and forestry are not perceived by these industries as significant. This may be due in part to inadequate methods for large-scale inoculum production. Monoxenic root-organ in vitro culture methods for AMF inocula production have also been attempted by various workers (Mohammad and Khan, 2002 Fortin et al., 2002) but these techniques, although useful for the study of physiological, biochemical, and genetic relationships, have limitations in terms of producing inocula of AM fungi for commercial purposes. Pot cultures in pasteurized soils have been the most widely used method for producing AM fungi inocula but are time-consuming, bulky, and often not...

Micronutrients

One of the most clearly defined interactions between Fe-stress response mechanisms and another micronutrient is an interaction with Zn in navy bean. The Zn-inefficient variety, Sanilac, readily exhibits Zn deficiency while the Zn-efficient variety, Saginaw, does not. It was also observed that Sanilac accumulates Fe under Zn-deficiency stress while Saginaw does not (Ellis, 1965). These two cultivars were grown hydroponically under Zn-deficient and Zn-sufficient conditions. Two of the three Fe-stress response mechanisms (reductant release and reduction of Fe3+ to Fe2+ at the root) were activated by Zn-deficiency stress in Sanilac (Jolley and Brown, 1991), but not in Saginaw. Consequently, Sanilac showed increased Fe uptake and aggravation of Zn-deficiency under Zn stress, while Saginaw prevents an imbalance of Zn and Fe by minimizing Fe uptake by actually reducing Fe reduction activity during Zn-deficiency stress.

Rootrainers

Hydroponic system for synthesis of ectomycorrhiza under steady state conditions. Modified from a drawing in Kahr and Arveby (1986). Fig. 22. Hydroponic system for synthesis of ectomycorrhiza under steady state conditions. Modified from a drawing in Kahr and Arveby (1986).

Water Potential

Water potential of a culture medium is practically expressed as the sum of water potential or osmotic potential of the nutrient liquid and water potential or matric potential of the supporting materials. Water potential of nutrient liquid is practically the sum of water potentials of inorganic salts, disaccarides (sucrose) and monosaccarides (glucose, fructose, mannitol and sorbitol) in the medium. Water potentials of organic substances other than sugar, such as vitamins, amino acids and plant growth regulators, are negligibly small because of their low molar concentrations. The water potential values of basic components in a solution of some widely used culture media and nutrient solutions for hydroponics are presented in the previous chapter (Chapter 2 Table 3). It is noted that water potential of MS (-212 kPa) is 3-6 times lower than those of White (-37 kPa) and Knudson C (-69 kPa). A practical equation for estimating water potential of sugar in the medium is shown in the previous...

Other Associations

Some plants, such as those of the mustard family (Brassicaceae) and the sedge family (Cyperaceae), lack mycorrhizae. In addition, most plants growing in flooded soils (or under hydroponics) do not form mycorrhizae nor do plants grown where conditions are extremely dry or saline. Also, plants growing in very fertile (i.e., nutrient-rich soils) have less-developed mycor-rhizae compared to plants growing in nutrient-poor soils.

Nutrients

Therefore scientists devised a simplified method for growing plants, called solution culture, or hydroponics. In this technique the roots of the plants are not in soil but in water, which contains the dissolved salts of those elements considered to be essential. That way, scientists can control and monitor the chemical composition of the medium in which the plants grow.

Salinity

Experiments that have compared hydroponics and soil at a range of salinities have found quite different qualitative and quantitative differences. Differences between two barley cultivars in growth, moisture content and Na+ accumulation were not apparent in hydroponics but significant differences occurred in soil (Tavakkoli et al., 2010) due to salt moving in the soil as it was watered, probably. Ca2+ deficiency is an artefact generated in hydroponics. Kopittke et al. (2010) provide a comprehensive analysis of the effect of any one cation on the activities of other cations in solution and the effect on plant growth rates. Short-term (2d) growth of cowpea seedling to Cl salts of Na+, K+, Ca2+ and Mg showed that growth was poorly related to activities in the bulk solution but closely related to activities at the outer surface of the plasma membrane. The addition of Mg Na+ or K+ resulted in Ca2+ deficiency in roots at Ca2+ concentrations less than 1.6 mM.

Plant Cultivation

The use of natural soil, both in forcing or open field production, is typical of the Hungarian sweet Capsicum industry. Growing without soil has only been recently achieved in greenhouses, which represent only 1-2 of the total production area. Because of the above-mentioned tilling, weeding is one of the most important cultivation projects. It is done by small garden machines or by hand in greenhouses. Drip irrigation is used for the irrigation and fertilization in 80 of the growing systems. Micro-dispenser irrigation is used for the rest. Overhead dispenser irrigation system (linear) is typical, but recently several farms switched to drip irrigation to save water.

Plant growth

Prior to initiating experiments, plant growth conditions should be carefully considered to ensure physical and physiological compatibility with a particular transport assay. Most physiological studies are initially carried out on seedlings for ease of handling, experimental control and efficiency, although many techniques can equally be applied to more mature plants if so needed. To name a few aerated hydroponics, aeroponics, mica-based artificial soils, saturated filter paper and vertically orientated sterile agar phytogel plates can be used to provide easy access to the roots. These methods can also give fine control over the nutrient content of the growth medium, which should, in any case, be carefully formulated to mimic physiological situations (it should be noted that full strength Murashige and Skoog, Hoaglands and or high sucrose will actually perturb plant growth see Gibeaut et al., 1997, for optimised hydroponic culture). At the same time, non-soil-based media may change...

Nematodes

In Australia, yield losses occurred where root-knot nematodes were detected from 9 to 15 months following planting, suggesting that sampling may be important in determining the need for postplant nematocide applications (Stirling and Nikulin, 1993). While soil sampling during plant growth (to estimate nematode populations) should be important for nematode management, in practice postplant nematode control is frequently applied as 'insurance', based on qualitative data, along with historical yield and nematode population information. The non-volatile nematiocides, such as oxamyl and fenamiphos, may be applied postplant as foliar sprays or through drip irrigation systems (Caswell and Apt, 1989).

Composition

It is well known that characteristic visual symptoms of specific nutrient deficiencies may appear in plant tissues. However, most of the classic deficiency symptoms described in textbooks are characteristic of acute deficiencies, that is when a nutrient is suddenly no longer available to a rapidly growing plant. In commercial cultivation in soilless systems, it is more common to find chronic deficiencies, that is the result of an insufficient supply of a nutrient compared to the demand of the plant (Berry, 2006). For chronic deficiencies, visual symptoms are not that clear so other methods have to be used to diagnose nutrient deficiencies. These methods are based on the key roles that nutrients play in plant metabolism because limiting levels of a nutrient affect the metabolic role in which it is involved.

Commercialization

The wide range of different microbial entities associated with nematode suppression offer a spacious array of different approaches and control options. Each organism will have its advantages and disadvantages, for example candidates that can be cultured very easily in vitro have advantages over those that are obligate pathogens that cannot, and again when it comes to other aspects of development such as formulation, storage and application, each organism will have its advantages and disadvantages. To date, there are already a number of products on the market (Table 12.1) and even this small amount outnumbers the number of new commercial nematicides and there are other potential organisms that are being developed (Hallmann et al. 2009). Most biological control products for nema-todes so far exist as a liquid or wettable powder formulations applied in furrow or through drip irrigation systems and one of the major drawbacks to these inun-dative practices is the volume of soil needed to...

Conclusions

Optimization of nutrition in soilless systems can be achieved by means of an accurate management of all factors involved (i.e. nutrient solution composition and concentration, water supply, nutrient solution temperature, dissolved oxygen concentration, EC and pH of the nutrient solution). If any factor affecting plant nutrition is under non-optimal conditions, plants may suffer from stress (Table II), and yields (quantity and or quality) may diminish. A precise diagnosis of plant stress caused by these factors is, hence, of great importance so that non-optimal levels of each factor could be determined and strategies for maximum benefits for growers can be planned (Fig. 3). Regarding methods for diagnosis of plant stress, many physiological techniques are available (Fig. 1). These methods are based on the fact that the above-mentioned factors affect the functioning of several plant physiological processes, and changes in these processes may be a sign of stress. The most important plant...

Tuber Induction

Tuberisation is stimulated by short days (long nights) although there is enormous genotyp-ic variation in the sensitivity to this requirement. The response pattern to tuberisation-induc-ing conditions is typical of a phytochrome response (4) and there is clear evidence that signals perceived in the leaves and transmitted to the stolons are involved in the control of tuberisation. Early work (5) showed that tuberisation could be induced in plants exposed to long pho-toperiod by grafting on leaves or stems from plants exposed to short days. More recently, Jackson et al. (6) produced transgenic plants of Solatium tuberosum spp. andigena (which naturally require day lengths of 12h or more to tuberise) with reduced levels of phytochrome B by antisense repression of the PHYB gene. The transgenic plants tuberise both under short and long days whilst wildtype plants only tuberise under long day conditions. Grafting experiments between the transgenic and wildtype plants indicated that...

Aminolevulinic Acid

Foliar Spraying Bad Effects

Exogenous application of ALA to fruits and vegetables is also reported to influence positively the quality of crop species. Spraying date palm fruits with 100 ppm ALA at different stages of fruit development increased fruit weight, fruit flesh percentage, fruit volume, and total and reducing sugar content although the positive response was dependent upon the application time or fruit developmental stage (Al-Khateeb et al. 2006). Application of 300 ppm ALA to apple fruits 20 days before harvest increased the total soluble solid content and decreased titratable acidity with no negative effect on fruit firmness and shelf life (Wang et al. 2004a) . It was also noted that no significant residue was found on the fruits which suggested that ALA could be used to improve apple quality. ALA application at the rate of 300 mg L-1 to 'Fuji' apple fruits 43 days before harvest significantly increased anthocyanin accumulation rate doubling the final anthocyanin content present in the fruit in...

Temperature

Root respiration increases with root temperature (Lyons et al., 2007 Rachmilevitch et al., 2006b Xu and Huang, 2000). Oxygen is consumed at a high rate and, in addition, oxygen solubility is reduced as temperature increases (Jones, 1997). Accordingly, high root temperature is generally associated to hypoxia stress in soilless systems (Incrocci et al., 2000). Respiration is a major avenue of carbohydrate consumption and may lead to shortage of assimilates when temperatures are too high. Actually, this fact has been proposed to be a primary factor responsible for root growth inhibition and dysfunction at high root temperatures (Kafkafi, 2008 Rach-milevitch et al., 2006b). The down-regulation of plant respiratory rates and the increase of respiratory efficiency by lowering maintenance and ion uptake costs are key factors for plant acclimation to high root temperatures (Lyons et al., 2007 Rachmilevitch et al., 2006b, b).

Evolution of roots

Figure 3.14 Irregularly branched rhizomes (A) and line drawing of a rhizome apex in transectional view (B) of Psilotum nudum in hydroponic culture. The original apical cell (a) produces merophytes outlined by heavy lines, and new apical cells (a') are formed in merophytes. (Modified from Takiguchi et al., 1997.) Scale bar 1 cm for (A), 50 im for (B). Figure 3.14 Irregularly branched rhizomes (A) and line drawing of a rhizome apex in transectional view (B) of Psilotum nudum in hydroponic culture. The original apical cell (a) produces merophytes outlined by heavy lines, and new apical cells (a') are formed in merophytes. (Modified from Takiguchi et al., 1997.) Scale bar 1 cm for (A), 50 im for (B). The most intriguing morphological trait is a tangled subterranean rhizome that branches frequently in equal or unequal fashion, with no regularity (Figure 3.14A). This contrasts with the regular dichotomously branching aerial stems. Such irregularity in the rhizome was once argued to be the...

Horticulture

Hydroponic growing without soil, in a watery medium A number of techniques are used in horticulture. New plant cultivars are developed through plant hybridization and genetic engineering. The number of plants is increased through plant propagation by seeds, cuttings, grafting, and plant tissue and cell culture. Plant growth can be controlled by pinching, pruning, bending, and training. Plant growth, flowering, and fruiting can also be controlled or modified by light and temperature variation. Further, growth and flowering can be altered by the use of growth-regulating chemicals and or plant hormones. The rate of plant growth and quality of plant products are controlled by managing fertilizer and nutrient application through fertigation or hydroponic solution culture. Posthar-vest product longevity is controlled by manipulating plant or product hormone physiology or by controlling respiration by lowering temperature or modifying environmental gas content. The scientific and...

Initiatives

Hydroponics might be a way to use vetiver hedges to filter dangerous materials out of surface waters. This is a speculative and untested idea but, as noted, the plant is at home in watery conditions. In one form of hydroponics the plants would be grown in an inert and highly pervious material through which the waters would pass. Coir dust, peatmoss, or perlite are possibilities. In another, vetiver might be grown with its massive roots dangling free in the water. This far-out idea, which works for other plants, requires something (old tyres perhaps) to keep the vetivers from sinking. Floating hedges might even be deployed across streams or canals to strip pollutants and dissolved nutrients out of the water flowing past. This

Synopsis

Distribution of nutrients in the soil is also heterogeneous in both space and time, and interception of nutrients also involves roots exploring and exploiting new volumes of soil. Uptake of nutrients depends on both affinity and capacity (flux density) of transport processes. High affinity transporters may provide enough capacity to avoid deficiency of major nutrients and sufficiency of trace nutrients, but are not able to supply the quantitative needs of the plant to support rapid growth. A spectrum of transport processes exists with lower affinity, higher capacity alternatives providing the uptake at higher external concentrations. Concentrations of major nutrients in the xylem are generally in the mM range, and external concentrations in the same range are generally needed to support maximal growth, even in well-mixed solutions, even though Km values for high-affinity transporters are often in the M range. Maintaining optimal growth in horticulture increasingly relies upon the...

Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

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