棉花开放花蕾主要来源于种间杂交的后代。我国将这一性状称作雌雄异熟系或柱头外露 ,为便于学术交流 ,本文建议应与国际上的称法相一致 ,即开放花蕾。开放花蕾是两对隐性重叠基因所控制 ,陆地棉与海岛棉均为单节隐性基因纯合体 ,但基因型不同 ,各带有一对位点不同的隐性基因。开放花蕾在棉花杂种优势利用中具有应用潜力。尤其是带有低酚标志性状的开放花蕾系“E- 81”,有助于提高制种效率。开放花蕾性状的雌、雄蕊发育进度 ,在减数分裂前是不同步的 ,但减数分裂后雌配子体的发育速度加快 ,最后达到雌、雄配子体同步成熟。当花柱外露长度达 6～ 7mm时 ,柱头的生理活性强 ,是杂交制种中授粉的有利时期。开放花蕾的天然异交率最高为 1 0 0 %,最低为 40 %,平均达 80 .4% Cotton flower buds mainly come from interspecific hybrid offspring. In our country, this trait is called dioeciousness or stigma. In order to facilitate academic exchange, this article suggests that it should be consistent with the international statement that flower buds should be open. Open buds are controlled by two pairs of recessive overlapping genes. Both G. hirsutum and G. barbadense are homozygous recessive genes, but different genotypes contain a pair of recessive genes with different loci. Open buds have potential applications in the utilization of cotton hybrids. In particular, the opening flower bud “E-81” with low phenolic properties helps to improve the efficiency of seed production. The developmental progress of female and stamens with open flower buds is asynchronous before meiosis, but the development of female gametophytes is accelerated after meiosis, and finally the female and male gametophytes are synchronized and mature. When the style exposed length of 6 ~ 7mm, stigma physiological activity is strong, is a favorable hybrid seed pollination period. The natural rate of natural outgrowth of open buds is 100% at the lowest, 40% at the lowest, with an average of 80.4%