The differentiation and development of growing tip in wheat was researched using a pair of near - isogenic lines (NILs). The results showed that branched rachis protuberances formed after developing to two - ridge period, and developed into spike branches. The developing progress of branched spike wheat included 9 periods, initial vegetative period, elongation period, single ridge period, two ridge period, branched rachis formation period, spikelet formation period, floret differentiation period, pistil and stamen differentiation period, and heading period. In phenology, the developing progress of the NILs was consistent to normal wheat prior to two ridge period, but the jointing stage, heading stage and blossom stage in branched spike line were 4.2, 2.3 and 1.4 days later than those in normal spike line, respectively. These indicated that the development of growing tip in branched spike wheat was continuous, and there was a branched rachis protrusions and formation period next to two - ridge period. This study would be helpful for understanding the development process of growing tip in branched spike wheat, and lay morphological foundation for realizing its genetic improvement , cultivation technique optimization and accelerating the utilization of this kind of grain wheat.%利用一对穗分枝差异的小麦近等基因系,研究其生长锥分化过程和发育规律.结果表明:穗分枝小麦发育至二棱期后,分枝穗轴突起形成,继而形成穗分枝；发育过程可分为9个时期:初生期、伸长期、单棱期、二棱期、分枝突起形成期、分枝小穗突起形成期、小花分化期、雌雄蕊分化期和抽穗始期；物候学方面,分枝小麦在二棱期之前的发育进程与正常穗型小麦一致,但分枝穗轴形成后,分枝小麦的拔节期、抽穗期和开花期分别要晚于正常穗型4.2、2.3d和1.4d,说明穗分枝小麦二棱期之后有一个分枝穗轴突起形成和伸长期.本研究有利于了解穗分枝小麦生长锥的发育进程,为进一步实现小麦遗传改良、优化栽培技术和加快该种质资源的利用奠定形态学基础.
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