水稻灌浆期间土壤含水量对根系生理活性的影响

Effects of Soil Moisture Content on Physiological Activity of Rice Root System During Filling Stage

在可控条件下设计水稻灌浆期间灌溉稻田旱作的不同灌溉方法,形成了3种土壤含水量,观察对水稻根系生理活性的影响。结果表明,不论灌溉方式的异同(土壤含水量异同)都不能改变随水稻花后生长中心转移、籽粒逐步灌浆、稻株渐熟及其伴生的根系生理活性的下降趋势,且水稻旱作此过程更强烈。在本试验条件下水稻始穗至收获约有45d,此间增灌1次——齐穗后21d即灌即排,使土壤基本达到饱和田间持水量,对根系呼吸强度与根系伤流量下降的缓解作用十分显著,但对根系伤流液中玉米素含量的下降趋势影响甚微。增灌1次的生理效果在于延缓根系的衰老,由此而产生的产量效果是提高水稻弱势粒群的灌浆功能,但对强势粒群的结实影响不大。因此,在本旱作技术中过分强调燥田割稻,而忽视维持水稻灌浆期适度土壤水分的做法不妥。

Three levels of soil water content were designed in irrigated paddy field to observe their physiological effects on rice root activities. It was found in this experiments that the growth center shifting, grain filling, ripening and root senescence were undergoing neglect of the water contents. It was also observed that the above changes was more significant in no-flooding irrigation treatment than the conventional flooding irrigation (CK). There were 45 days from initial heading to harvesting, and one-time irrigation was given during this period in this experiment to saturate the soil with water. By the water saturation, the degradation of both root respiration and root exude were significantly improved with little effects on the decreasing process of zeatin content in roots exude. Therefore one-time watering during filling stage could delay senescence of the root system, which enhanced the filling process of inferior spikelets. It is suggested that keeping a suitable water contents in soil during harvesting would facilitate the grain filling.