The spike differentiation and flowering characteristics in Kentucky bluegrass (Poa pratensis) were closely observed periodically throughout the development stages. The whole spike differentiation could be divided into 5 stages, which were the differentiation stage of first bract primordium, the differentiation stage of primary branch primordium, the differentiation stage of secondary and third branches primordial, the differentiation stage of spikelet and floret primordial, the stage of stamen and pistil primordial formation. The whole flowering progress in a spike of Kentucky bluegrass lasted about one week. The flowering order of the branches in the spike cob was from up to down, but the flowering order of florets in a single spikelet was from down to up, the flowering order of each branch was that the top flower blossomed first and then in bottom-up order till the flower in the top of penultimate spike came into blossom. According to the relationships between spike differentiation stages and phenophase, the regulation practices for spike differentiation and yield formation in Kentucky bluegrass should focus on the specific phenophases.%试验观察了草地早熟禾Poa pratensis 的幼穗分化过程和开花习性,将草地早熟禾幼穗分化过程划分为5个时期:第一苞原基分化期,一次枝梗原基分化期,二、三次枝梗原基分化期,小穗及颖花原基分化期,雌雄蕊形成期.草地早熟禾整个穗的开花过程历时约1周,总穗轴上一次枝梗的开花顺序是自上而下,小穗上颖花的开花顺序是自下而上;各枝梗上开花顺序是顶端花先开,然后再自下而上直至顶端倒数第2穗上颖花开完为止.根据幼穗分化时期与物候期的关系,针对草地早熟禾穗发育和种子产量形成的调控措施应在不同的物候期进行.
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