不同放牧强度对人工草地牧草生殖分配及种子重量的影响

Effects of Stocking Intensity on Grass Reproductive Allocation and Grain Weight on the Artificial Grassland

不同放牧强度对白三叶、红三叶、鸭茅的生殖分配及种子千粒重影响极显著。一定强度的放牧干扰有利于提高休牧后三叶草的花序密度 ,但鸭茅花序密度却随放牧强度的提高而出现明显下降。放牧草地三种牧草种群的生殖分配均低于对照草地。在放牧草地 ,随放牧强度的提高 ,白三叶生殖分配逐渐增加 ,红三叶及鸭茅生殖分配逐渐减少。提高放牧强度后 ,三叶草千粒重出现递减趋势 ,而鸭茅却出现递增趋势 ,在无放牧干扰草地 ,三叶草种群趋于生产数量较少的大粒种子 ,在放牧干扰下 ,趋于生产数量较多的小粒种子 ;

On the artificial grassland of middle high mountainous region of China, the stocking intensity was strictly controlled at three levels according to intake rates: G1(55%)、G2(65%) and G3(80%). Field experiment results showed that there was significant relationship between stocking intensity and the reproductive allocation( RA ), grain weight of T. repens, T. pratense and D. glometata . Inflorescence density of clover increased after medium intensity stocking(G1 or G2)while there was a significant negative relationship between stocking intensity and inflorescence density of D. glomerata . The rate of reproductive allocation of the three grasses on the sward grazed was lower than that on the sward non grazed. On the grazed sward, the RA of T. repens increased gradually while that of T. ptatense and D. glomerata decreased with the stocking intensity increased. On the non grazed sward, the RA of T. repens, T. ptatense and D. glomerata were 4 4%、1 9%、and 25 7% respectively; on the G1 sward, the RA percentages were 0 9%、0 9%、4 5% respectively; on the G2 sward, the RA percentages were 1 2%, 0 2% and 1 6% respectively; on the G3 sward, the RA percentages were 2 1%、0 1% and 0 5% respectively. After the stocking intensity was raised, the thousand grain weights of two clovers decreased while that of D. glomerata increased drastically( P <0 001). On CK、G1、G2 and G3 swards, thousand grain weights of T. repens were 0 4857、0 4744、0 4558、0 4486g respectively; the thousand grain weights of T. ptatense were 1 5196 、1 4172 、1 4096 and 1 3897g respectively; and those of D. glomerata were 0 8502、0 9096、0 9983 and 0 9991g respectively. The clover populations were apt to produce more smaller seeds under stocking pressure and fewer bigger seeds during non stocking season. The D.glomerata population, however, was apt to produce fewer bigger seeds under stocking pressure and more bigger seeds during non stocking season.