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在低土水势下,叶片水势下降,且随着叶位的下降,叶片水势下降早而快。在150～900μmol photons·m~(-2)·s~(-1)的光强范围内,稻株群体净光合与光强呈线性关系,且随着土水势的下降,光强对光合的促进作用逐渐减弱。土水势、光强和气孔导度对光合强度的影响存在互作效应,在低土水势下,除气孔导度外,另有其它限制光合的因素存在。低土水势引起叶片质膜透性增加,同时刺激超氧化物歧化酶(SOD)活性升高,水分胁迫造成的膜伤害很可能包含自由基伤害过程。低土水势对水稻根系活力的影响随生育时期和品种的不同而异,灌浆中、后期,较低的土水势能延缓根系的衰老。
Under the low soil water potential, the leaf water potential decreases, and as the leaf position decreases, the leaf water potential drops earlier and faster. Under the light intensity range of 150 ~ 900μmol photons · m -2 · s ~ (-1), there was a linear relationship between net photosynthesis and light intensity of rice plant population. With the decrease of soil water potential, photosynthesis Promoting effect gradually weakened. Soil water potential, light intensity and stomatal conductance have an interaction effect on photosynthetic intensity. Under low soil water potential, besides stomatal conductance, there are other factors that limit photosynthesis. Low soil water potential caused the increase of leaf plasma membrane permeability, while stimulating superoxide dismutase (SOD) activity increased, the membrane damage caused by water stress is likely to include free radical damage process. The effect of low soil water potential on the root activity of rice varied with the growth period and varieties. The lower soil water potential delayed the root senescence during the middle and late stages of filling.