Effects of soil water saturation on rice growth and development

Intersubspecific hybrid rice Xeiyou 9308 and Liangyoupeijiu were used as the test materials, three level of soil water content were designed during grain filling in irrigated field to observe their effects on translocation and allocation for carbohydrate. The results showed that in conventional flooding or non-flooding cultivation, the exported rates of stored carbohydrate from stem and photophate from the leaves were 60% and 90% respectively. The exported rate of carbohydrate was decreased significantly in the non-flooding cultivation. The filling grains were the major sinks for carbohydrate storage during grain filling stage. Grains received nearly 50% leaf-sheath-stored carbohydrate and 80% leaf-stored photophate. At the non-flooding condition, the absorbing rates of grains were significantly decreased by 10% and 20% from leaf sheath and from leaves photophate, respectively. Dry stress caused much decrease in absorbing ability for inferior grains. It was also observed that one time water saturation during grain filling stage, the degradation of both root respiration and root exudates was significantly slowed down with little effects on the decreasing process of zeatin content in roots exudates.