土壤水分对免耕水稻根系生长的影响

2013年早季和晚季,以吉优716为试验材料,盆栽条件下研究土壤水分对免耕水稻根系生长、形态的影响及其与地上部生物量积累和产量的关系。试验设3种土壤水分条件:W100、W85、W70,分别为水稻全生育期保持土壤饱和含水量的95%~100%、80%~85%、65%~70%。结果表明:W70处理土壤水分严重抑制了免耕水稻拔节期根系的生长,根干质量显著下降;土壤水分对抽穗期根系直径影响较大,对总根长、体积和根干质量影响不大;W70处理成熟期根系出现早衰,根长、根直径、表面积、总体积和根干质量均显著下降。土壤水分主要影响直径0.0~1.5mm根的生长,特别是直径0.0~1.0mm的根。不同时期各处理间根冠比差异不显著,在拔节期和成熟期W70处理根冠比均低于W100和W85,在抽穗期W70处理根冠比高于W85处理。免耕水稻根干质量与地上部生物量和产量均呈显著正相关。重度水分胁迫显著抑制了拔节期根系生长,引发成熟期根系早衰,进而使地上部生物量积累减少,产量下降。轻度水分胁迫对免耕水稻根系生长影响较小。土壤水分对根系调控最核心的区域是根直径0.5~1.0mm区间。

Effects of soil moisture on root growth of no-tillage rice

Pot experiments were conducted in the early seasons and the later season of 2013.In each season,the hybrid rice cultivar Jiyou71 6 was planted under saturated soil moisture of 95%-100%(W100),80%-85% (W85)and 65%-70% (W70).The results showed that the root growth was seriously limited by soil moisture of W70 at the stage of elongation.The root dry weight significantly decreased. The effect of soil moisture on root diameter was the biggest at the stage of heading,but that on root sur-face area,volume and dry weight was small.The root of W70 appeared early aging at the stage of mature. The length,diameter,surface area,volume and dry weight of root was significantly reduced.The root with diameter between 0.0-1.5 mm was crucial to the root growth regulation under different soil mois-tures.The root with diameter between 0.0-1.0 mm played decisive roles.There was no significant differ-ence on root shoot ratio under different soil moistures and at the different stages.The ratio of shoot and root of W70 was lower than those of W100 and W85 at the stages of elongation and mature.The ratio of shoot and root of W70 was higher than that of W85 at the stage of heading.The dry weight of root and aboveground biomass,grain yield was significantly positively correlated in no-tillage rice.The root growth was inhibited by severe water stress at the stage of elongation.The root of W70 showed earlier senescence than that of W100 at the stage of mature.The aboveground biomass reduced,leading to the decrease of grain yield.Mild water stress did not make the root senescence slow down.The root with di-ameter between 0.5-1.0 mm was crucial to soil moisture on regulating the root growth under different soil moistures.