1．适时要严格掌握第一次喷施九二O的时期，施用过早，会导致倒二节和倒三节过度伸长，植株过高；造成只拔节不抽穗，即使抽穗，穗子变白；下部颖花大量退化，小分蘖难以抽出，易倒伏。使用过迟，穗颈节老化不易伸长，难以解除母本包颈现象，造成柱头外露率和结实率低，产量不 1. Timely to strictly grasp the first spraying 920 O period, the application too early, will lead to two and three inverted section over-elongation, plant too high; resulting only jointing not heading, even heading, ears white; lower Ying Degradation of flowers, small tillers difficult to extract, easy to lodging. Use too late, panicle neck aging is not easy to stretch, it is difficult to lift the female parent package neck, resulting in stigma exsertion rate and seed setting rate is low, the yield is not