Photosynthesis temperature

Table 2. CO2 fixation rates and optimum photosynthesis temperature (OPT) of two species- Acaena cylindrostachya and Senecio formosus of neotropical superparamo along an elevation gradient. Assimilation rates...

Water Stress Effects on Canopy Photosynthesis, Temperature, Transpiration and Shedding of Leaves and Fruit in Cotton 733... 

Non-calorimetric studies of effects of hydrostatic high pressure on plant sources are more common. In general, pressure effects on plant metabolic rates are small, but some distinct changes have been noted in growth, photosynthesis, temperature responses, and plant structure [48]. Interpretation of the role of pressure on plant metabolism remains uncertain. Hypotheses that have been framed to explain pressure effects are generally written in terms of volume changes and structural transitions in chloroplasts and in lipid membranes, but there are equally tenable alternative explanations such as pressure effects on equilibria. 

From SCRP spectra one can always identify the sign of the exchange or dipolar interaction by direct exammation of the phase of the polarization. Often it is possible to quantify the absolute magnitude of D or J by computer simulation. The shape of SCRP spectra are very sensitive to dynamics, so temperature and viscosity dependencies are infonnative when knowledge of relaxation rates of competition between RPM and SCRP mechanisms is desired. Much use of SCRP theory has been made in the field of photosynthesis, where stnicture/fiinction relationships in reaction centres have been connected to their spin physics in considerable detail [, Mj. 

The effect of temperature fluctuations on net carbon dioxide uptake is ikustrated by the curves in Figure 18. As the temperature increases, net photosynthesis increases for cotton and sorghum to a maximum value and then rapidly declines. Ideally, the biomass species grown in an area should have a maximum rate of net photosynthesis as close as possible to the average temperature during the growing season in that area. 

The possible effects of increased atmospheric CO2 on photosynthesis are reviewed by Goud-riaan and Ajtay (1979) and Rosenberg (1981). Increasing CO2 in a controlled environment (i.e., greenhouse) increases the assimilation rate of some plants, however, the anthropogenic fertilization of the atmosphere with CO2 is probably unable to induce much of this effect since most plants in natural ecosystems are growth limited by other environmental factors, notably light, temperature, water, and nutrients. 

The putative feedback involves the influence of emissions of this aerosolgenic gas, (CH3)2S, that influences cloud albedo and hence either the temperature of the seawater in which the phytoplankton live or the amount of light available for their photosynthesis. Figure 17-9 represents the hypothetical feedback loop, and emphasizes that even the sign of the feedback is not known. Contradictory evidence has been developed... 

Bjorkman, O. (1981). The response of photosynthesis to temperature. In Plants and their Atmospheric Environment, ed. J. Grace, E.D. Ford and P.G. Jarvis, pp. 273-301. Oxford Blackwell Scientific Publications. 

In certain plant habitats or niches, access to resources depends crucially upon rapid growth under conditions of climatic stress. Examples of this phenomenon are particularly obvious on shallow soils in continental climates where the growth window between winter cold and summer desiccation may be extremely short. In deciduous woodlands in the cool temperate zone an essentially similar niche arises in the period between snow melt and closure of the tree canopy. Both circumstances provide opportunities for high rates of photosynthesis and mineral nutrient capture in the late spring but depend upon rapid expansion of roots and shoots in the low-temperature conditions of the late winter and early spring. 

Photosynthesis and gas exchange of leaves are affected by many stresses including drought, flooding, salinity, chilling, high temperature, soil compaction and inadequate nutrition. Many, but not all, of these stresses have symptoms in common. For example, stomatal conductance and the rate of assimilation of CO2 per unit leaf area often decrease when stress occurs. Further, it is possible that several of the stresses may exert their effects, in part, by increasing the levels of the hormone abscisic acid (ABA) in the leaf epidermis. This hormone is known to close stomata when applied to leaves. 

Aoki, S. (1986). Interaction of light and low temperature in depression of photosynthesis in tea leaves. Japanese Journal of Crop Science, 55, 496-503. 

Bjorkman, O. (1987). Low-temperature chlorophyll fluorescence in leaves and its relationship to photon yield of photosynthesis in photoinhibition. In Photoinhibition, ed. D.J. Kyle, C.B. Osmond and C.J. Arntzen, pp. 123-44. Amsterdam Elsevier. 

Long, S.P., East, T.M. Baker, N.R. (1983). Chilling damage to photosynthesis in young Zea mays. 1. Effects of light and temperature variation on photosynthetic CO2 assimilation. Journal of Experimental Botany, 34, 177-88. 

Cyanobacteria, prokaryotic algae that perform oxygenic photosynthesis, respond to a decrease in ambient growth temperature by desaturating the fatty acids of membrane lipids to compensate for the decrease in the molecular motion of the membrane lipids at low temperatures. During low-temperature acclimation of cyanobacterial cells, the desaturation of fatty acids occurs without de novo synthesis of fatty acids [110, 111]. All known cyanobacterial desaturases are intrinsic membrane proteins that act on acyl-Hpid substrates. 

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