Marta A Vattuone

A. R. Sampietro Universidad Nacional de Tucum n, Tucum n Argentina Haryana Agricultural University Hisar, India Enfield (NH) Jersey Plymouth 234 May Street Post Office Box 699 Enfield, New Hampshire 03748 United States of America General enquiries info scipub.net Editorial enquiries editor scipub.net Sales enquiries sales scipub.net Published by Science Publishers, Enfield, NH, USA An imprint of Edenbridge Ltd., British Channel Islands Printed in India 2009...

Observations

The leachate is filtered through a Whatman 1 filter paper and used for bioassay or chemical analyses. Leachate volumes are large enough to be used for greenhouse pot assays. Make at least three independent leachate collections (N 3) for each plant species. Figure 7 Pluviotron to simulate leaching of plant materials. Water drips through holes at the bottom of tray A to tray B, simulating a raindrip. Tray B contains chopped plant material. Water drips from tray...

Phenolic Compounds

Phenolic compounds occur ubiquitously in plants (Pridham, 1960 Harborne, 1982 Harborne and Turner, 1984). They are synthesized in response to stress conditions such as infection, wounding and UV radiation, etc. (Nicholson and Hammerschmidt, 1992 Beckman, 1999). These compounds are a very diversified group of phytochemicals derived from phenylalanine and tyrosine (Shahidi, 2000 2002 Shahidi and Naczk, 2004). Some of them are shown in Fig. 1. Production of phenylpropanoids, stilbenes, lignans,...

Procedure B

In saturated steam distillation, the plant does not come in contact with the water the steam is injected through the plant material placed on perforated trays (Fig. 4). To shorten the duration of treatment and limit the alteration of the constituents of the EO, it is possible to operate under moderate pressure (1-3 bar). The consequence of this pressurization is an increase in temperature, but the quality of the product may suffer. Figure 4 Saturated steam distillation. The steam is injected...

Materials and equipments required

Assay tubes, Erlenmeyer flasks, pipettes analytical balance with 0.01 mg sensitivity spectrophotometer or filter photometer capable of measurement at 415 nm, equipped with a 1 cm path length microcuvette vortex mixer. Figure 6 Reaction of Al3+ with a flavonoid molecule (Source Adapted from Woisky and Salatino, 1998). Figure 6 Reaction of Al3+ with a flavonoid molecule (Source Adapted from Woisky and Salatino, 1998).

Stemflow

It is the rainwater running down the bole of trees and shrubs. It can accumulate a significant amount of natural products which are transported to the tree floor and into the soil. Stemflow collars are often used to capture stemflow for chemical analysis (Fig. 6B). The collars are constructed from a polyurethane foam applied around the bole of a tree or shrub. The foam is tightly sealed against the bole creating an effective water barrier. After placing the foam, a trough is dug in the top of...

Preface

Allelopathy is a newly emerging multidisciplinary field of agricultural research. Till now, a lot of allelopathy research work has been done in various fields of Agriculture and Plant Sciences. However, no standard methods are being used by various workers due to lack of compendium on the techniques, hence, the results obtained are not easily comparable with each other. This situation has caused a lot of problems to researchers working in underdeveloped third world countries in small towns,...

Procedure A

Simple steam distillation consists in immersing the plant material to be treated (intact or crushed) directly into a flask filled with water, which is then boiled (Fig. 3). A steam current from another water boiling flask passes through the mixture. The heterogeneous vapours are condensed on a cold surface and the EOs are separated according to the differences in density and immiscibility. Figure 3 Laboratory set-up for steam distillation (Source Moldoveanu and David, 2002). Figure 3 Laboratory...

Suggested Readings

Blum, U., Gerig, T.M., Worsham, A.D., Holappa, L.D. and King, L.D. (1992). Allelopathic activity in wheat conventional and wheat-no-till soils development of soil extract bioassays. Journal of Chemical Ecology 18 2191-2221. Caswell, E.P., Tang, C.S., De Frank, J. and Apt, W.J. (1991). The influence of root exudates of Chloris gayana and Tagetes patula on Rotylenchulus reniformis. Revue Nematologie 14 581-587. Chou, C.H. (1989). Allelopathic research of subtropical vegetation in Taiwan IV....

Allelopathy and Allelochemicals

Allelopathy refers to any process involving secondary metabolites produced by plants, microorganisms, viruses and fungi that influence the growth and development of agricultural and biological systems (Narwal, 1994). It has been established that allelopathy offers great potential to (a) increase agricultural production (food grains, vegetables, fruits and forestry), (b) decrease harmful effects of modern agricultural practices multiple cropping, leaching losses from N fertilizers,...

Carbohydrates And Related Compounds

Carbohydrates are the most abundant class of organic compounds found in living organisms. They originate as products of photosynthesis, an endothermic reductive condensation of carbon dioxide requiring light energy and the pigment chlorophyll. Carbohydrates are a major source of metabolic energy, both for plants and for animals that depend on plants for food. Apart from the simple sugars, they provide a means of storing energy (starch) that meets this vital nutritional role and transport of...

Terpenoids And Steroids

Terpenoids and steroids are elaborated from common precursors. They constitute the largest known group of plant secondary metabolites. Majority of them are specific to the plant kingdom, but they also occur in animals, e.g. sesquiterpenoid insect pheromones and juvenile hormones, diterpenes of marine organisms (Coelenterate, Spongiae). Triterpenes are specific to the plant kingdom and like steroids, arise via squalene, from mevalonate. The mechanism of formation of these last compounds is...

Colorimetric Reactions

Beer Lambert Law Graph

Sgariglia, Jose R. Sober n, Emma N. Quiroga and Marta A. Vattuone Colorimetry, the measurement of the absorption of visible light, allows the first qualitative and quantitative estimation of the phytochemicals present in a plant, soil or water sample. Colorimetric methods allow the assessment of an unknown colour in reference to known colours Thomas, 1996 . In practice, they provide qualitative or semiquantitative estimations rather than quantitative...

Statistical analysis

Root Exudate

Data are analyzed as indicated in Statistical analysis of Experiment 8. Experiment 10 Double-Pot Trapping System Principle A plant species is grown in a brown glass container filled with an inert medium and watered with Hoagland's solution Fig. 8 . After proper development of the Figure 8 Schematic diagram of the double-pot continuous root-exudate trapping system used to collect root exudates Source Caswell et al., 1991 . Figure 8 Schematic diagram of the double-pot continuous root-exudate...

Precautions

Use very clean glassware and redistilled solvents and avoid contact of the extraction solvent with the stopcock grease or plastic tubing. Be careful with the contact of the preparation with Parafilm, a thermoplastic sealing material employed in the laboratories. This material is soluble in the mentioned solvents and gives a solution containing w-alkanes that can contaminate the extracted material. Otherwise, the solution of the dissolved Parafilm can be used as standard during the purification...