旱涝急转条件下水稻水分利用效率变化研究

Research on the Change of Water Use Efficiency of Rice under the Drought-Flood Abrupt Alternation Condition

为探究水稻在旱涝急转条件下光合效率及水分利用变化规律,从而为研究水稻经历旱涝急转灾害后产量变化及灌溉方式提供科学依据,以Ⅱ优898水稻为研究对象,采用四因素三水平正交实验,研究了旱涝急转条件下,水稻叶片水分利用效率WUE_(leaf)及气孔导度gs、蒸腾速率E、光合速率A等参数的变化。结果表明干旱程度和淹水深度对光合作用的累积作用最明显;A/gs与叶气温差呈线性相关,但旱涝急转导致响应积极性降低;分蘖期末~拔节孕穗期初WUE_(leaf)~g_(s)均可用上凸抛物线描述,此阶段干旱引起绝对光合速率的降低是影响生育期生物量积累的控制因素。拔节孕穗中后期WUE_(leaf)~g_(s)均可用下凸抛物线描述,经历旱涝急转导致叶片提前衰老,绝对蒸腾速率下降,WUE_(leaf)的增加并不能促使产量的补偿,可提前控制土壤含水量,减少非必要的水资源消耗。

The research is intended to explore the variation of photosynthetic and water use efficiency of rice under drought-flood alternation condition,so as to predict yield scientifically and provide an optimum irrigation mode of rice under the disaster.Changes of water use effi⁃ciency WUE_(leaf),stomatal conductance gs,transpiration rate E and photosynthetic rate A are studied by orthogonal experiment on II you 898 rice.The results show that the significant changes of photosynthesis product accumulation when drought degree and flooding depth have changed.A significant linear relationship is displayed between A/gs and leaf-air temperature difference in any case,but a relatively insensi⁃tive response after a drought-flood abrupt alternation.From the end of tillering stage to the beginning of jointing and booting stage,the rela⁃tion between WUE_(leaf) and gs can be described by convex parabola.The absolute photosynthetic rate controlled the biomass accumulation in the whole growth period.In the mid-late stage of jointing and booting,the relation between WUE_(leaf) and gs can be described by a concave parab⁃ola.The increase in WUE_(leaf) is unable to induce a compensation of yield due to an early senescence of leaves and the decreases in absolute transpiration rate at the stage.So we had better provide less water in late growth period of rice when it is exposed to an early drought-flood abrupt alternation,to avoid unnecessary water waste.