Effects Of Different Water And Nitrogen Treatments On Rice Growth And Yield Formation

YLY6 and HY3 were employed to investigate the effects of different water and nitrogen treatments on rice growth and yield formation, this experiment contained two water treatments (continue flooded, CF and alternate drying and wetting, AWD) and four nitrogen levels, and was conducted under field and pot conditions.The results obtained were summarized as following:1. Different combination of nitrogen and water treatments had different effects on grain yield, but no interaction effects were observed between water treatments and nitrogen treatments. Application of nitrogen fertilizer significantly increased rice grain yields in comparison with no nitrogen fertilizer application. However, comparable grain yield were achieved in N1(108 kg N ha-1), N2 (148.5 kg N ha-1) and N3 (189 kg N ha-1). Moreover, no differences were observed in grain yield between the CF and AWD. For yield components, N1, N2 and N3 produced comparable panicle numbers, which was higher than NO. But grain weight of NO was higher than that of N1, N2 and N3. There were no differences in spikelets per panicle and grain filling percentage between CF and AWD.2. There was no significant difference in grain yield among three treatments of nitrogen applications, and water consume increased as nitrogen application increased3. Under field conditions, spikelets per panicle and per unit area differences were the main cause for differences in grain yield between varities. During the rice growth period, relatively high rainfall, relatively low groundwater table depth, and relatively high soil water potential of AWD (>-10kPa) caused no drought stress; Relatively high soil background nitrogen (yield of the plot without nitrogen application was 6-7 t ha-1), was the main reason of no significant yield difference amount three nitrogen treatment.4. Under pot experiment conditions, decreasing water input had different effects on grain yields of the the varieties. Yield of HY3 decreased significantly under AWD treatment, but there was no significant difference in yields of YLY6 under two water conditions; Different nitrogen treatment affect yield significantly, and the two varieties performed identically.The decreses in grain yield were mainly due to declines in both sink cacapity and translocation from stems to grains in HY3 under water saving treatment.Relatively low soil water potential of rehydration under AWD treatment (-50kPa) and continued high atmosphere temperature during flowering period (>35℃) may be the common causes of filling rate degree of HY3.