Aftereffects of water-nitrogen interaction on rice at jointing stage

In order to reveal the aftereffects of different nitrogen and water regulation levels on rice, pot experiments were carried out to study the aftereffects of short-term and long-term physiological indexes in different water-nitrogen interaction models at jointing stage. The results showed that optimal combination of water and nitrogen had compensation effect on physiological activity in a short-term after rewatering, while long-term aftereffect of delaying senescence was found at late growth stage. The single factor of water and nitrogen had significant influence on chlorophylls, fluorescence parameters, MDA, etc. in the short term after rewatering, and the collaborative interaction of water and nitrogen had reached to significant level in 15 d after rewatering. The interaction effect of water and nitrogen is different for different water stress level. The yields of heavy-drought treatments increased with the improvement of nitrogen supply, but were lower than other treatments. Accordingly, the heavy-drought should be avoided in rice jointing stage, and soil moisture content can't hold less than 70% soil water rate. The yields of sufficient irrigation and slight-drought treatments reduced with the increasing of nitrogen supply. Therefore, high level of water and fertilizer at jointing stage did not assure high yield. The treatment of rewatering combined with lower nitrogen supply after slight-drought can obtain the best effect on water saving and yield guarantee.