Photosynthesis parameters

Gu J., Yin X., Struik PC., Stomph TJ., Wang H. Using chromosome introgression lines to map quantitative trait loci for photosynthesis parameters in rice (Oryza sativa L.) leaves under drought and well-watered field conditions. Journal of Experimental Botany 2012 63(1) 455-469. 

Chapter 7 - The application of methodology of spatial-energy interactions (P-parameter) to main stages of photosynthesis is given. Their energy characteristics are calculated. The values obtained correspond to the reference and experimental data. 

Chapter 8 - Spatial-energy characteristics of many molecules and free radicals are obtained. The possibilities of applying the P-parameter methodology to structural interactions with free radicals and photosynthesis energetics evaluation are discussed. The satisfactory compliance of calculations with experimental and reference data on main photosynthesis stages is shown. 

Keywords Spatial-energy parameter, free radicals, structural interactions, photosynthesis. 

In this approach we give quantitative and semi-quantitative evaluation of spatial-energy interactions at main stages of complicated biophysical process of photosynthesis based on the utilization of initial atomic characteristics. The analysis of results after the application of P-parameter methodology shows that they correspond to reference data both in the direction and energetics of these processes. 

The chapter will be divided into sections according to the protein systems and the occurring paramagnetic species. Furthermore, some recent attempts to obtain EPR parameters of paramagnetic species in photosynthesis by semiempiri-cal, DFT and ab initio calculations are described. 

Estimates of modeled parameters of particular oceanic processes of the carbon cycle range widely. For instance, from the data of various authors the estimates of assimilation of carbon from the hydrosphere in the process of photosynthesis range from 10 GtC/yr to 155 GtC/yr. The value 127.8 GtC/yr is most widely used. However, because of large variations in these estimates, calculation of the C31 coefficient is fraught with great uncertainty therefore, specifying it requires numerical experiments using other, more accurate data. 

Illumination affects the rate of photosynthesis Rp. The R parameter as a function of E has a maximum at some optimal value of Ernax, which drifts from this critical value when illumination increases or decreases. The maximum Rp at various latitudes ip is located at depths that vary as a function of season (i.e., sun elevation). Thus, in tropical zones this variability with depth is most pronounced. On average, the photosynthesis maximum is located at depths of 10m-30m, and in open water bodies it can be observed at depths below 30 m. Here Emax = 65 cal cm 2 da 1 85 cal cm-2 da-1. At depths where E = 20 cal cm-2 da- -25 cal cm-2 da-1, photosynthesis decreases in proportion to E. An apparent suppression of phytoplankton by light is observed at E > 100 cal cm 2 da 1. These estimates are quite different in northern latitudes, where the photosynthesis maximum is located, as a rule, at the surface. 

Examples for compounds are given in Figure 8.1, and the regression analysis equation is provided below for the QSAR of triazine derivatives in photosynthesis (Draber, 1992). The inhibitory potency expressed as a pl50 value is equal to a lipophilicity parameter tt (log of the partition coefficient P), an electronic substitution parameter a (the Hammett constant) and to a lesser degree to a steric component Es (the Taft constant). 

Phosphate is usually considered as a parameter that limits photosynthesis in the Black Sea. According to Sorokin [23], the mean content of phosphate in the upper mixed layer down to the lower boundary of the euphotic zone is close to 0.10-0.20 xM in spring-summer. In autumn its mean content varied between 0.01 and 0.02 xM in cyclonic eddies and between 0.12 and 0.18 iM at their periphery over the slopes. In winter the phosphate content in the upper water layer usually rises due to the vertical mixing, thus attaining 0.15 to 0.40 xM. 

Biodiesel to Fuel a Large Power Plant. Researchers at ASU s Center for Bioenergy and Photosynthesis have calculated that a 25 x 25 km field of bioreactors using cyanobacteria to fix carbon could uptake all of the carbon dioxide produced by a 1.6 GW power plant and subsequently provide the biomass as lipid to fuel the power plant. The parameters necessary to achieve this goal are a seven percent power conversion efficiency for photosynthesis, 40 percent conversion efficiency of biomass to fuel, 50 percent conversion efficiency of fuel to electricity, and 80 percent conversion efficiency of land area covered by the bioreactors. This system would then be carbon neutral in operation and produce about 1.6 GW of electrical power. The key to making this feasible is to achieve a seven percent power conversion efficiency for cyanobacteria. Moore noted that the area required to produce a specified amount of energy scales directly with the energy conversion efficiency of the system or device. 

Stomatal opening leading to the C02 uptake that is necessary for photosynthesis results in an inevitable loss of water. A useful parameter relating the two fluxes and showing the total C02 fixed (benefit) per unit water lost... 

Bernacchi, C.J., Pimentel, C., and Long, S.P. 2003. In vivo temperature response functions of parameters required to model RuBP-limited photosynthesis. Plant Cell Environ. 26 1419-1430. 

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