氮素形态对旱作水稻水分蒸腾效率和对缺水敏感性影响

The resource of freshwater is very much limited in China but more than 80% of the freshwater used in agriculture finds its way in the process of rice production. The serious shortage of freshwater is threatening or will threaten China's rice production. Therefore, rice cultivation in aerobic soil condition is becoming a substitute for rice cultivation in waterlogged soil condition. The agricultural practice demonstrated that almost the same rice grain yield could be obtained under the condition of aerobic cultivation as under that of waterlogged cultivation but more than 100% of freshwater could be saved in aerobic cultivation system compared with the traditional one, i.e. waterlogged cultivation system. The all eco-environmental conditions are completely different between the two cultivation systems but very little has been known about the physiological adaptation of rice to the shift from waterlogged to aerobic condition. This needs a lot of research work to be carried out so that the basic theory can be proposed for the extending of rice cultivation in aerobic soil condition. The most significant physiological shift of rice plant from waterlogged to aerobic condition is that the rice is mainly fed with ammonium in the former but with nitrate in the later. The physiological characteristics occurred during the process of the shift and their relation to water use efficiency should be firstly clarified. In the present research project both pot experiments of water culture (simulating water stress incubation) and of soil culture and field experiments were carried out to study the response of rice to different forms of nitrogen and its relation to water use efficiency by rice crop. The main results were as follows. (1) Different varieties of rice crop responded in different ways to different ratios of NH4+-N and NO3-N, in which nitrate promoted significantly the development of lateral roots mainly because of the increased IAA and decreased CTKs in the roots by nitrate. (2) Soil mulching was a key step that made the rice cultivation in aerobic soil condition successful. (3) The depths of groundwater affected significantly the accumulation of total sugar cane, Ca2+, Cl- in rice plant, which, in turn, determined the grain yields of rice crop. (4) A mixed provision of ammonium and nitrate to rice crop could lead to more nitrogen uptake and better growth of rice crop than in single provision of either ammonium or nitrate in both normal solution culture and in simulating water stress culture. More NO3-N was taken up by rice crop in simulating water stress culture than in normal solution culture while more NH4+-N was adsorbed by rice crop in normal solution culture than in simulating water stress culture. (5) Significant effects of periodic and whole stage of water stress on rice growth were found, thus, the whole stage of water stress (as in aerobic soil) could increase the adaptation of rice crop to water stress to a great extent compared with the periodic water stress. (6) The behavior of stomata of rice crop cultivated in aerobic soil condition was controlled by both the ABA and IAA in the plant.

在水分供应充分和不同亏缺程度情况下研究旱作水稻不同生育期及不同温度光照强度下的NO3-对NH4+配比对作物生长形态、发育和阴阳离子吸收、体内离子（包括羧酸）平衡与渗透势平衡及对秆内、根土和叶气界面水分传导的影响。明确氮素形态影响作物水分状况、水分蒸腾效率的生理学机制，完善旱作水稻高产水分利用的氮素调控技术。