高平原某些草地禾草的季节干物质产量,主要取决于第一次刈割的物候期。抽穗前刈割,中断了开花期的迅速生长而降低第一次刈割的产量;但开花后刈割,又使其后的再生期处于较短日照和较低气温的环境,降低以后的产量。不同的禾草种类其开花习性不同,因此,牧草生产的管理亦不尽相同。 The seasonal dry matter production of some grassy grasses in the high plains depends mainly on the phenophase of the first mowing. Mowing before heading cut off the rapid growth of the flowering stage and reduced the yield of the first cutting; however, the mowing after flowering allowed the subsequent regeneration period to be in a shorter sunshine and lower temperature environment, reducing the later yield . Different grass species have different flowering habits, so the management of grass production is also different.