【摘要】 <正> 1978年以来,我们对水稻的吸肥动态以及不同时期追施氮肥对籽粒的作用进行了研究,同时也分析了穗肥施用时期对作物产量及品质的影响。应用示踪法研究这些课题,可以获得一般方法难于得到的有价值的材料,有助于阐明上述问题。1978年,我们在河北省芦台农场进行了水稻吸肥动态的研究;1978年及1979年,我们又在中国农科院原更多还原

【Abstract】 Field tracer experiment using isotope ¹⁵N demonstrated that the rate of fertilizer-N utilization by the total plant was in the following order : from turn green to tillering stage 6.76%, from turn green to primordia stage 24.17%, from turn green to maximum ear emergence 42.60% and from turn green to repenning 40.06%.The content of fertilizer-N and soil-N in rice plant was determined. About 70% of plant-N was derived from soit-N and the remaining 30% from fertilizer-N. The mineral N-fertilizer from paddy soil during the growing period of rice played a very important role in rice production. Therefore, the problem of how to maintain high soil fertility deserves serious attention.It was observed that when fertilizer-N was spread on the soil surface, the utilization of fertilizer-N was increased with the delay of application, but the retention of N in soil and loss of fertilizer-N were decreased.The results of this experiment also showed that with the delay of application of fertilizer-N the percentage of N in rice kernels increased from 65.08% to 75.61%, corresponding to an increase of fertilizer-N utilization from 19.86% to 39.84%. Thus, the earlier the time of N application, thehigher the rate of fertilizer-N utilization. However, in rice production it is not sufficient to attain high fertilizer-N utiliatiou only. Consideration must also be paid to the nitrogen nutrition of rice plant in the earlier growing stage, which will result in greater vegetative growth, and moderate fertilization be applied in the later growing stage in accordance with the soil nutrient status.更多还原