Quantitative Evaluation of Control System of Crop Production under the Unfavorable Soil Conditions

从水分关系的角度研究了干旱、减土和紧实土壤条件下的植物生产调控系统。控制生长的主要过程有两个：一是通过抑制根系吸水来实现水力控制，二是通过根系中的任何物质进行非水力控制。在生长在高密度土壤上的水稻植株中观察到了水力控制，在这种土壤中，植株生长受到抑制，同时叶水势降低。在干旱和土壤退化的情况下，水稻气孔导度的下降比叶片水势的下降更为敏感，从根系采集的木质部汁液抑制了非胁迫植株的气孔开放。我们试图建立一个模型框架，以指示干旱条件下的植物生产。在考虑水分利用效率不变的情况下，植物生产用蒸腾速率表示，蒸腾速率随根量和土壤储水量的变化而变化。该模型没有将控制过程分为液压控制过程和非液压控制过程，但如果将这两个过程适当地结合起来，可以变得更加有用。

Control system of plant production under drought, soil reduction and compacted soil conditions was investigated from a stand point of water relation. There were two dominant processes controlling growth ; the first one is hydraulic control through inhibition of water absorption in roots and the second is non-hydraulic control by any substance derived from root system. The hydraulic control was observed in rice plants grown under high compacted soils where suppression of plant growth accompanied with reduction of leaf water potential. The non-hydraulic control was considered in rice grown under drought and reduction of soils where stomatal conductance reduced more sensitive than that estimated by reductions of leaf water potential and xylem sap collected from the root system inhibited stomatal opening of non-stressed plants fed the xylem sap. We tried to make a model framework which indicates plant production under drought conditions. In the model when water use efficiency is considered to be constant, plant production was illustrated by transpiration rate which changes by both amounts of root and soil reserved water capacity. This model does not separate the control process as hydraulic and non-hydraulic control process but can became more useful if the process will be appropriately combined.