Assimilates allocation

Heinonsalo, J., Hurme, K. R. Sen, R. (2004). Recent C abelled assimilate allocation to Scots pine seedling root and mycorrhizosphere compartments developed on reconstructed podzol humus, E- and B-mineral horizons. Plant and Soil, 259, 111-21. 

Although stream standards are the most reaUstic in light of the use of the assimilative capacity of the receiving water, they are difficult to administer and control in an expanding industrial and urban area. The equitable allocation of poUutional loads for many industrial and municipal complexes also poses pohtical and economic difficulties. A stream standard based on minimum dissolved oxygen at low stream flow intuitively implies a minimum degree of treatment. One variation of stream standards is the specification of a maximum concentration of a poUutant (ie, the BOD) in the stream after mixing at a specified low flow condition. 

Various centers of metabolic activity exhibit a high demand for photosynthates such that there is competition within the plant for available resources. Thus, during the development of the plant, at any moment in time, there exists a dominance hierarchy for photosynthates. In the Jerusalem artichoke, photosynthetically fixed carbon resources are allocated among maintenance reactions, production of additional structural components, and deposition within specialized storage sites within the plant. The allocation hierarchy shifts not only as the plant develops, but also in diurnal cycles. Therefore, photosynthate allocation depends upon both timing and assimilate availability. 

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. 

A model of crop growth, development, and yield formation was used to compare Jerusalem artichoke and chicory — the two main agricultural sources of inulin (Meijer et al., 1993). The pattern of assimilation in the two crops was very different. Chicory is a biennial, with only vegetative growth in the first season and dry matter distributed to the storage roots during the second season. A greater fraction of total production is diverted to structural stem matter in Jerusalem artichoke. Most dry matter is allocated to the stem until the reproductive phase of Jerusalem artichoke, mainly in the form of structural stem material, but also as stored carbohydrates. 

Animals differ markedly in the way in which the energy they take in is allocated to different activities. The relationships between energy assimilation, utilization, and expenditure may be summarized by the following energy budget equation ... 

Under conditions of low photorespiration, about 90% of photochemical product is allocated to COj fixation. The progression from light limitation to light saturation in photosynthesis is illustrated in Pig. 3 A which shows a typical light saturation curve for photosynthesis illustrated in the shmb Juanulloa aurantiaca. The quantum requirement per mole COj fixed (on an incident irradiance basis) increases as the irradiance and rate of CO2 assimilation increase. The higher the flux the lower the efficiency of COj assimilation (Fig. 3B). As the ATP and NADPH requirements for COj fixation are independent of... 

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