Studies On Grain Yeild And Physiological Characteristics Of Water-saving And Drought-resistance Rice Hanyou113

Rice is the higher water-consuming food crops. The study on rice water-saving and drought resistance was conducted by selecting the appropriate breeds and irrigation regime, to increase water use efficiency. It is one of the effective ways to alleviate the water crisis in agriculture. The experiment use water-saving and drought-resistant rice Hanyou113 and high-yielding rice Yangliangyou6 by setting different water treatments,namely, Flooding, Saturated and Drought throughout the growth period after transplanting. It studied the differences in grain yield and physiological characteristics between different rice genotype. The preliminary results are as follows:1. Under Saturated treatments, height, growth period, shoot biomass and yield of Hanyou113 and Yangliangyou6 showed no significant differences compared with the control of Flooding treatments, yet presented an upward trend; Drought significantly reduced plant height, shoot biomass and grain yield, and extended the growth period. The main cause for rice yield reduction in the experiment was the decrease of grain number per spike and setting rate. Under Flooding and Saturated treatments, Hanyou113 showed no significant differences compared with Yangliangyou6. Meanwhile its grain yield was significantly higher than that of Yang liangyou6 by 38.9%. Drought significantly reduced grain yield of two varieties, and Reduction of Hanyou113 is lower. This shows that the water-saving and drought-resistance Hanyou113 can achieve high yield under conventional flooded conditions, has the potential of yield increase under saturated irrigation, and maintains a higher yield under drought stress, boasting a relative broader application prospect.2.Under different water treatments, SPAD, air-leaf temperature difference, and photosynthesis rate of Hanyou113 and Yangliangyou6 presented the trend of first increase,and then decrease during the growth period, peaking at the Heading Stage. Drought stress significantly decreased leaf water potential, but the leaf water potential of Hanyou113 was significantly higher than that of Yangliangyou6, which shows in time of lacking water, Hanyou113 could still maintain a higher level of leaf water potential, and owns better drought-resistance. The fact that intercellular CO₂ concentration did not decrease when photosynthesis rate decreased under drought stress, shows that under the drought stress set in the experiment, photosynthesis rate of rice leaf is not dominated by the spiracle factor, and as the drought stress lasted longer. SPAD, air-leaf temperature difference, and photosynthesis rate of Hanyou113 and Yangliangyou6 in different stages of growth under Saturated treatment showed no significant in comparison to Flooding treatment. Drought stress significantly increased leaf WUE, and leaf WUE of Hanyou113 was significantly higher than that of Yangliangyou6 at Heading Stage.3. Under Flooding and Saturated treatments, during the booting stage, SPAD,Photosynthesis rate, Stomata conductance of Yangliangyou6 and Hanyou113 increased from the 1st leaf from the top to the 2nd leaf from the top, but then decreased from the2 nd leaf downwards; during the milk stage, these values decreased from the top leaf to the bottom leaf. However, intercellular CO₂ concentration maintained consistent, and did not decrease as stomatal conductance decreased, which shows the decrease of Photosynthesis rate of lower leaf may be caused by the restriction of non-spiracle factors.Photosynthesis rate of Hanyou113 decreased at a lower rate with the decline of leaf position, which shows a slower leaf aging compared with Yangliangyou6. Under Drought treatment, during booting stage, SPAD and leaf water potential of all leaf positions of Hanyou113 and Yangliangyou6 decreased to different extent compared with Flooding treatment, yet SPAD and leaf water potential of the middle leaf were higher than that of the top leaf and the bottom leaf.Under Drought treatment, Hanyou113 can still get higher grain yield, maintaining higher leaf water potential, higher gas leaf temperature and water use efficiency at heading stage; the leaf senescence speed slower under flooding and saturated treatment,suggesting that it has a better water-saving and drought resistance. The study results could provide theoretical basis for water-saving and drought-resistance rice breeding.