刈割对一年生短生草雀麦生长和繁殖的影响

Effects of defoliation on growth and reproduction in the short-lived annual plant Bromus japonicas

雀麦(Bromusjaponicas)为一年生短生草,是准噶尔荒漠早春优质牧草。对雀麦自然种群物候进行观测,在拔节期设置两个刈割高度,分别为2.5 cm(矮,S)和7.6 cm(高,T),研究不同刈割强度对雀麦植物生长和繁殖的影响。结果表明:(1)刈割降低了植株高度、旗叶长度、生物量和总生物量;T处理和S处理植株的高度分别比对照降低了28.2%和40.1%,生物量比对照降低了29.9%和60.6%。(2)刈割显著降低了雀麦果穗的长度、小穂的数目、果实数目和果实的重量;随着刈割强度的增加,雀麦果穗的长度、果实数目和果实重量显著降低;T处理和S处理果穗的长度分别比对照降低了29.1%和41.6%、果实数目分别降低了54.5%和71.7%。(3)刈割后雀麦的果实重、果实数目、生物量和总生物量的补偿指数均显著小于1,补偿生长模式为不足补偿;S处理的补偿生长能力显著小于T处理。研究结果对于揭示短命植物的补偿生长模式以及雀麦资源的合理利用提供科学数据。

Bromus japonicas is a high-quality forage grass that is typically short-lived and found in the Junggar desert in early spring.This study involved phenological observations based on natural populations.Experimental treatments involved plant clippings at two heights,2.5 cm(short,S)and 7.6 cm(tall,T)at the jointing stage to study the effects of different defoliation intensities on the growth and reproduction of B.japonicas.The results showed:(1)Clipping had decreased the height,length of flag leaf,biomass and total biomass of the plants.Compared with the control,the plant height of T and S treatments decreased by 28.2%and 40.1%,and the biomass decreased by 29.9%and 60.6%,respectively.(2)Defoliation significantly reduced the fruit ear length,number of spikelets,number of fruits and weight of fruits.With the increase of clipping intensity,the length of spikelet,number of fruits and fruit weight decreased significantly.The length of fruit ear in T and S treatments compared to the control were reduced by 29.1%and 41.6%,and the number of fruits was reduced by 54.5%and 71.7%,respectively.(3)The compensation index of fruit weight,fruit number,biomass and total biomass after clipping was significantly less than 1,and the compensation growth pattern of B.japonicas was inadequate.The compensatory growth ability of S treatment was significantly lower than that of T treatment.The results provided scientific basis for revealing the compensatory growth pattern of short-lived plants and rational utilization of brome resources.