两年分期播种表明，南京自然温光条件对多年生黑麦草幼穗分化进程的影响，主要表现在单棱至雌雄蕊原基分化阶段。种子萌发至单棱期的天数与日均温度呈负相关。单棱至二棱需要某种低温的诱导，二棱的出现是黑麦草通过春化阶段的形态标志，也是幼穗能否发育完全的转折点。进入二棱后，高温长日照加速幼穗分化进程。幼穗分化的天数与每穗种子粒数呈显著正相关。单棱至护颖分化的日均温较低，小花分化至抽穗的光照时数较多，有利于提高黑麦草种子粒数和产量。 The two-year sowing showed that the effects of Nanjing natural light and temperature on the spikelet differentiation of perennial ryegrass were mainly manifested in the stage of primordial differentiation from single rib to female stamen. The number of days from seed germination to single-edge was negatively correlated with the average daily temperature. A single edge to two edges need some kind of low temperature induction, the appearance of two edges is the morphological symbol of the ryegrass passing through the vernalization stage, and it is also a complete turning point for young spike development. Into the two edges, high temperature and long sunshine to accelerate spike differentiation process. There was a significant positive correlation between the number of spikelets per panicle and the number of spikelets per panicle. The average daily temperature of single ridge to longiflora differentiation is lower, and the number of light florets differentiated from the floret to heading is more, which is beneficial to increase the seed number and yield of ryegrass.