Factors That Control Stomatal Movements

Stomata are constantly opening and closing in response to many environmental factors, including humidity, light, temperature, and CO2 concentration, to maintain a viable balance between CO2 gained in photosynthesis and water lost in transpiration (Heath and Mansfield 1969 Hetherington and Woodward 2003). Figure 8.1 is a summary of these factors. A positive sign in the figure shows Transient effects + Increase Decrease due to change in guard cell turgor Passive stomatal opening not due to change...

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350 700 350 700 Well- Draughted watered 350 700 350 700 Well- Droughted watered FIGURE 1.19 Growing season integrated whole-plant biomass accumulation, water consumption, and transpiration efficiency for P. pinaster (cluster pine) and Q. petraea (Durmast oak) grown under two CO2 concentrations (350 and 700 J,mol mol) and two water treatments (well-watered or pot capacity and drought-stressed or watered when soil water content reached 40 of pot capacity). Mean values ( standard errors) not...

Leaf Resistances

Four resistances control CO2 transport (photosynthesis) the boundary layer resistance, the cuticular resistance, the stomatal resistance, and the mesophyll resistance. See Kirkham (2005, pp. 388-392) for a discussion of leaf resistances. We shall discuss the cuticular resistance and the stomatal resistance in the last paragraph of this section. The boundary layer resistance is due to the thin layer of still air above all leaves, and its thickness (which determines its resistance) depends on the...

Transpiration Under Greenhouse Conditions

An increase in stomatal conductance causes an increase in transpiration. This is illustrated in Figure 10.1, where there is a positive sign between leaf conductance and transpiration. However, conductance and transpiration are decoupled to some extent, particularly in greenhouses, where insufficient cooling of the leaves through transpiration causes heat damage that occurs at high radiation (Nederhoff et al. 1992). This is explained in Figure 10.1, which depicts a course of events following an...

Composition Of The Soil Atmosphere

Boussingault and L wy (1853) were early researchers who studied the composition of the atmosphere of the soil. (See Appendix for a biography of Boussingault.) Their research, along with that of others after them, established five general characteristics of the soil atmosphere (Taylor and Ashcroft 1972, p. 365) 1. The sum of the CO2 and O2 in the soil air is nearly the same as the sum of these two components in the air above the soil. 2. The CO2 content usually increases with depth. 3. The CO2...

Gymnosperm Versus Angiosperm Trees

While a tremendous amount of work has been done studying and modeling trees under elevated CO2 (Thornley and Cannell 1996 Medlyn et al. 1999 Valentini et al. 2000), few studies apparently have compared specifically gymnosperms and angiosperms under elevated CO2 and drought, even though models have considered them separately (Whitehead et al. 2001, 2004). Gymnosperms dominate the cold regions, because of their vascular system. The two conducting cells in the xylem tissue are tracheids and vessel...

Carbon Isotope Ratios Of Plants With Different Photosynthetic Pathways

Let us now turn to carbon isotopes, which Hungate et al. (1997) and others (Prevost-Boure et al. 2009) have used in root studies to distinguish CO2 produced from different sources. The numerical value of carbon isotope ratios is conventionally reported as 513C. The number represents the difference between the ratio of 13C-12C found in a given sample and the ratio that exists in a universal standard, expressed as a per mill ( e, or number of one-thousandths) deviation from the standard. The...

Contents

Chapter 1 Elevated Atmospheric Carbon Dioxide Photosynthesis of C3 and C4 Photosynthesis of CAM Field Studies with Controlled Environment Studies with Gymnosperm versus Angiosperm CAM Biography of Charles David Chapter 2 Elevated Carbon Dioxide in the Soil Composition of the Soil Atmosphere 29 Composition of the Soil CO2 and O2 in Soil and CO2 with Depth in the Seasonal Amounts of CO2 and CO2 Emissions as Affected by Diurnal CO2 Organic Rainfall, Irrigation, and CO2-Amended Irrigation...

Appendix

Charles David Keeling, the first person to measure accurately the rising levels of CO2 in the atmosphere, was born on April 20, 1928, in Scranton, Pennsylvania, United States (Brown 2005). He was the son of Ralph Franklin and Grace Noerr (Sherburne) Keeling. He married Louise Barthold and they had five children Andrew, Ralph, Emily, Eric, and Paul (Marquis Who's Who 2004). He graduated from the University if Illinois in 1949 (Marquis Who's Who 2004), majoring in chemistry (Brown 2005). He got a...

Carbon Dioxide Enrichment In Greenhouses

We are not going to consider greenhouses, because our main concern is the increasing CO2 in the open air, which is occurring due to man's activities. However, in this section we briefly cover elevated CO2 in greenhouses, where CO2 enrichment has long been used to promote growth (Northen and Northen 1973, p. 40). Enriching the greenhouse air with additional CO2 improves the growth of flowers, increases their quality and numbers, and often hastens plants into bloom. The amount that gives best...

Phenology Under Elevated Co2

For many vegetable crops grown in greenhouses, elevated CO2 up to about 1000 imol mol usually shortens the time taken until flowering begins (Murray 1997, p. 171). The difference in flowering time may range from a few days (e.g., begonia or Begonia sp.) to more than 15 days, as in Saintpaulia ionantha Wendl. (African violet). For some, the extent of advancement may depend on the CO2 concentration. Thus, flowering is advanced by about 1 week in Callistephus chinensis Nees (China aster) plants...