Assimilates partitioning

Agarwal, P.K. Sinha, S.K. (1984). Effect of water stress on grain growth and assimilate partitioning in two cultivars of wheat contrasting in their yield stability in a drought-environment. Annals of Botany, 53, 329-40. 

Some progress toward the control of assimilate partitioning by means of growth regulators has been made, and one practical outcome is the novel system of apple production known as the... 

Riesmeier, J.W., Willmitzer, L., and Frommer, W.B., Evidence for an essential role of the sucrose transporter in phloem loading and assimilate partitioning, EMBO J., 13, 1-7, 1994. 

Pre-screen for activities of some types of yield enhancers (that exist mainly in theory at present) or of compounds that may alter assimilate partitioning. 

Ncube B, Finnic JE, Van Staden J. Carbon-nitrogen ratio in vitro assimilate partitioning patterns in Cyrtanthus guthrieae L. Plant Physiol Biochem 2014 74 246-54. 

Figure 9.9 AFC model for a bulk partition coefficient Dt = 2 and Ca /C0 = 5. Subscript a refers to the contaminant. Parameter r is defined in equation (9.4.12). The critical r value rc = 0.25, calculated from equation (9.4.18), separates the fractionation dominant field from the assimilation dominant field. The labels on the curves refer to the values of C,iq7Co. ...

By regulating the partitioning of electrons between NADP+ reduction and cyclic photophosphorylation, a plant adjusts the ratio of ATP to NADPH produced in the light-dependent reactions to match its needs for these products in the carbon-assimilation reactions and other biosynthetic processes. As we shall see in Chapter 20, the carbon-assimilation reactions require ATP and NADPH in the ratio 3 2. 

Timing during the development cycle is also a critical factor. For example, during the first half of the developmental cycle, photosynthate is partitioned predominantly into stem storage sites (Incoll and Neales, 1970 McLaurin et al., 1999). However, with the onset of tuber bulking, allocation within the plant shifts dramatically. Now a major portion of new assimilate preferentially moves into the rapidly developing tubers, and assimilate previously stored in the stems begins to be recycled to the tubers. 

Some pollutants are assimilated by oiganisms to a greater extent than others, and, if they are lipophilic, they may accumulate. Measures of exposure to chemicals which bioaccumulate in tissue are easily accomplished through an analysis of tissue residues. In the absence of tissue residues, empirical constants are often derived and used by ecotoxicologists to predict bioaccumulation examples include the octanol—water partition coefficient, which approximates a chemical s behavior between the lipid and water phase (see Section 8.3), the bioconcentration factor (BFC), and the bioaccumulation factor (BAC). These last two are defined as follows ... 

DON concentrations of 4-8 pM have been observed in the relatively weak upweUing area off the northwest coast of Spain (Alvarez-Salgado et al., 1999). HUl and Wheeler (2002) reported values of 7 pM DON in upweUed waters off the Oregon coast. These are similar DON concentrations to the open ocean as summarized Table 17.3 of HiU and Wheeler (2002). Some of this DON is upweUed e.g., water at 50 m depth off Oregon had a mean value of 5.98 (HUl and Wheeler, 2002). Another source is from production by phytoplankton as they partition newly assimilated NO3 into particulate nitrogen and DON that is released (Bronk et al., 2006 Wetz and Wheeler, 2003). 

Kraemer, G. P., Mazzella, L., and Alberte, R. S. (1997). Nitrogen assimilation and partitioning in the Mediterranean seagrass Posidonia oceanica. PSZNIMar. Ecol. 18, 175—788. 

One interesting implication of the qualitative model shown in Fig. 29.4 is that the size of the trophic effect is a function of the partitioning of assimilated nitrogen between new biomass and excreta. The greater the excretory losses, the greater the difference in between an animal and its food. This implies that the trophic... 

Piniak, G. A., Lipschultz, F., and McClelland, J. (2003). Assimilation and partitioning of prey nitrogen within two anthozoans and their endosymbiotic zooxantheUae. Mar. Ecol. Prog. Ser. 262, 125-136. 

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