【作者】 李绍军；

【导师】 梁宗锁；

【作者基本信息】 西北农林科技大学 ， 植物学， 2009， 硕士

【摘要】 干旱是我国西部地区农业面临的最大影响,旱灾对农业产量的影响非常巨大。然而部分学者研究认为在作物生长期中适度的干旱并不总是带来灾难性的后果,因此有可能在节约农业用水的同时并不导致减产,甚至可能在恢复供水后产生补偿生长效应。通过三年的研究,确认玉米在旱后复水可以产生补偿生长效应。适度干旱后复水营养器官首先等量补偿生长,经济目标器官则表现为低补偿生长,在反复干旱后玉米穗减产严重。可见胁迫程度过深时玉米整体表现低补偿生长,如果在拔节、抽穗等关键时期遭遇干旱时会出现伤害明显的现象。补偿生长效应是玉米在受到外界水分胁迫后的一种适应性生理反应机制。在光合作用方面,表现在气孔导度随胁迫加深而下降、进而导致蒸腾减弱、光合受阻。光合日变化、光饱和曲线都对水分的胁迫有明显反应。复水后,玉米迅速恢复光合能力的表现,光饱和曲线、光合日变化曲线都趋向对照水平。但是,由于干旱过程中已经影响到光合产物的生产与累积,因此最终向生殖器官分配量的减少状况会出现,复水后玉米穗的重量有不同程度的下降,反复干旱的产量减少最严重。在这个过程中,其它生理过程也参与响应干湿交替的生长环境刺激。例如脯氨酸作为渗透调节物质在受旱时含量升高,复水后下降:抗氧化酶体系也有响应干旱信号的作用;叶片中的硝酸还原酶活性变化也反映在这个过程中有受到调节的作用。该研究结果提示在生物节水实践中,复水补偿生长效应非常复杂,在玉米拔节、抽穗等关键需水时期应保证水分供应,否则会导致严重减产;旱后复水可以出现等量补偿,但总耗水量无显著差异;如果反复干旱则导致低补偿或者伤害现象的发生。同时应关注选育水分胁迫复水后能维持或者快速修复光合能力、有较强渗透调节与抗氧化修复能力的品种。更多还原

【Abstract】 Drought affects agriculture greatly especially to western areas in China. Generally, the agriculture output will decrease when crops meet moisture stress. However, some researchers raise an issue that disasters are not always performed if the crops were in a moderate degree stress. The idea was based on the phenomenon being observed that in some cases compensation growth will occur to crops after stresses removed. More and more studies are carried out in order to develop proper ways to maintain the yields while saving water.Having studied for three years, I confirmed that post-drought rewatering can lead to compensation growth effect on maize. The effect is assigned to equivalent, low and hazardous compensatory growth. Vegetative organs almost covered after rewatering and it is priorty happened before economic organs which are always lower the compensatory. In the situation of alternated cyclic drought and humidity, the corn cob yield decreased badly. The compensation will be lower when stress degree increase, and harms will be happened especially when drought appeared in the key period of maize life such as stem elongation and earing period.It is a physiological adaptation that the compensatory effect of maize occurred by stages under rewatering after stress. In certain aspects, the stomatal conductance decrease when stress deepening, the transpiration rate reduced and photosynthesis collapsed. The diurnal variation of photosynthetic rate and the curves of photosynthetic light response are also reacted to the water treatments. Those two curves tend to the controls’ rate when maize rehydrated. Unfortunately, the dry matter distribution to reproductive organs decreased due to the accumulation from photosynthesis being diminished. It’s more seriously when alternated cyclic drought and humidity. In the process of adaptation, other biological response react to the environment stimulation such as the content of proline, membrane permeability, antioxidant enzymes’ and nitrate reductase activity.The results showed that maize compensatory growth is extremely complexity. Equivalent, low and hazardous effects could happen any time in the practice of biological water-saving. During stem elongation and earing period, maize need sufficient water supply. Breeding species of restoring photosynthetic ability, regulating osmotic adjustment, rehabilitating antioxidant enzyme system and other items helping crops to adapting stress are also needed concerned to practices.更多还原