温度变化下两种冰草种子萌发的动态特征

Dynamic Characteristics of Tow Wheatgrass Species Seed Germination in Changing Temperature Condition

种子萌发行为在沙漠植物的持续存在与种群动态中具有关键作用。本研究以沙地广布种米氏冰草和冰草为研究对象,分析温度变化对种子萌发格局的影响。结果表明,米氏冰草和冰草的发芽率均在25℃时最高,且呈单峰连续曲线。在25℃及以上时,米氏冰草的发芽率高于冰草,25℃以下则相反。发芽指数均随培养时间的延长呈降低趋势,米氏冰草萌发持续25 d,冰草持续8～21 d,且发芽指数的格局变化为:前期,冰草显著高于米氏冰草;中期,米氏冰草显著高于冰草;后期,无显著差异;米氏冰草的累积发芽率随培养时间延长呈缓慢增长趋势,冰草的累积发芽率则在萌发初期迅速增长,然后趋于平稳状态。二者的日发芽率高峰都出现在第3天,但米氏冰草的发芽率远远低于冰草。

The germination of seeds is crucial for protecting sandy plant and population dynamics.The research used the wild Agropyron michnoi and cultivated Agropyron cristatum widely distributed in sandy land as research object to study the Dynamic Characteristics of Seed Germination in changing temperature condition.The results indicated that both A.michnoi and A.cristatum had the highest germination rate at 25 ℃ and an Arabian continuous curve.Over 25 ℃,the germination rate of A.michnoi was higher than that of A.cristatum,when it was below 25 ℃,the outcome was different.Their germination index was all decreased step by step with the extension of incubation period.Seed germination of A.michnoi extended 25 days,while that of A.cristatum was nearly 22days.Changes of germination index pattern was clearly,in the first-phase A.cristatum was distinctly higher than A.michnoi,when in the mid-time,A.michnoi was significantly greater than A.cristatum,but in the late states,there was no marked difference between the two.Accumulating germination rate of A.michnoi was slowly increasing with the extension of incubation period,while that of A.cristatum was growing fast during the initial period of germination,then stable state was reached.The germination rate for both of them approached a climax at the third day,yet the germination rate of A.michnoi was much lower than that of A.cristatum.