众所周知,杂交水稻的制种过程需要两个亲本材料——雄性不育系和恢复系,然而水稻不育系常常具有“包穗”(即抽穗期穗子被包裹在叶鞘内难以抽出)的特性,为杂交稻制种带来很大困难。研究表明,最上部茎节内活性赤霉素水平的降低是导致不育系包穗的主要原因。生产上往往需要在后期大量喷施“九二零”(赤霉素)来克服杂交制种中不育系的包穗问题。然而,“九二零” It is well-known that hybrid rice requires two parents, male sterile lines and restorer lines, for seed production. However, the male sterile lines in rice usually have a “panicle” (that is, the panicle is difficult to pull out when the panicle is wrapped in the sheath) Characteristics, for hybrid rice seed produced great difficulties. Studies have shown that the reduction of active gibberellins in the uppermost stem segments is the main reason for the inclusion of male sterile lines. Production often need to spray a large number in the latter part of the “1990” (gibberellin) to overcome the cross-breeding of male sterile lines panicle problems. However, “nine two zero ”