Study On Water And Nitrogen Use Characteristics Of Aerobic Rice Under Different Water And Nitrogen Conditions

The experiment was done in Changping station of China Agriculture University in 2002 and 2003. The variety is aerobic rice 297. This paper studied the effects of different irrigation amounts and levels of nitrogen on plant growth and developments, yield and yield components, water demands and utilization, water use efficiency (WUE), nitrogen uptake, coupling effects of water and nitrogen for irrigation and nitrogen fertilizer managements of high yield and saving water aerobic rice production. The main results were as follows:(1) Compared with other irrigation treatments, the treatment of w2 that limited water irrigation amounts before PI demonstrated the significant advantages of higher dry matter, yield and yield components, better root growth condition, water amounts and intensity in full growth periods, WUE and water stress factor. This treatment was considered as preferred mode for aerobic rice production of high yield and saving water in Beijing region. The synthetical performance under sufficient irrigation treatment of wl was inferiored to the performance under w2. The performance of w3 (treatment that limited water application amount after PI) and w4 (severe water stress treatment) were lower than that one of wl and w2. Compared with the other levels of nitrogen (N0,N150,N225 kg-hm-2), the level of 112.5 kg-hm-2 resulted in higher nitrogen uptake in harvest, more proportion of nitrogen distribution to grains, better agronomy efficiency and apparent efficiency. This level was considered as recommended measure of nitrogen application in Beijing region. The nitrogen application of 150 kg-hm-2and 225 kg-hm-2 were excessive.(2) The corp coefficient of aerobic rice 297 was about 1.1. It wasn't influenced by soil nitrogen content.(3) Under different water treatments, the range of light saturation point and light compensation point were 978-1205 mol-m-2-s-1 and 4-40 mol-m-2s-1 respectively. Water stress decreased the light saturation point and increased the light compensation point. The light utilization ability was reduced.(4) Under dry farming condition, the relationships of the yield , WUE and water utilization amounts were nonlinear at 5% level of probability. According to the experiment results, it was considered that the efficient water irrigation amounts for high yield is around 780mm.(5) Under wl treatment, the total nitrogen uptake in above-ground plant at harvested stage were as follows: it was 109 kg-hm-2 when no nitrogen was applied, but under the other three levels of nitrogen, it was obviously high, changed between 187 to 191 kg-hm-2. The proportion of nitrogen distributed to stems and leaves was more than 50% and to grains was under 40%.(6) Integrated the results of water, nitrogen and the coupling effects of the two factors, it is concluded that under the conditions of the fertile soil and relative low sunlight hours, the proper water management takes w2 that limited water application amounts before PI and the proper nitrogen measure is 112.5 kg-hm-2 by three application times.