郊区后季稻一般在8月20日前开始幼穗分化,这时期在生理上,由营养生长为主转入生殖生长为主,生长中心转移到幼穗,是培养大穗、决定每穗粒数的关键时期。由于稻株以氮代谢为主转入碳氮代谢并重,因而既要有一定的氮素,又要有丰富的碳水化合物,以供应幼穗分化,以及根、茎、叶生长的需要。这时,如果氮素供应过多,就会 Subsequent post-season rice generally began to panicle differentiation before August 20, during this period, from the vegetative growth to the reproductive growth, the growth center shifted to the panicle, which was to cultivate the panicle and determine the number of grains per panicle The critical period. Since the rice plants are mainly nitrogenous metabolized into carbon and nitrogen metabolism, both nitrogen and rich carbohydrates are needed to supply the spike differentiation and the growth of roots, stems and leaves. At this moment, if there is too much supply of nitrogen, it will be