草原毒害草—黄花棘豆种子萌发的影响因素探讨

黄花棘豆(Oxytropis ochrocephala)是我国西部高寒草甸一种危害严重的毒害草,为明确黄花棘豆种子的萌发特征,本文主要探讨发芽前处理和温度对黄花棘豆种子发芽状况的影响。结果表明:温度对黄花棘豆种子萌发的影响最为显著:在10℃~25℃范围内,随着温度的升高种子发芽率增大;并且,恒温条件下其发芽率均高于与之对应的变温条件。其中,25℃恒温条件下其发芽率最高为15.3%;10℃/5℃变温时最低,仅为1.3%。另外,随着温度的上升,种子发芽指数增大、发芽时间缩短、硬实率降低:10℃/5℃时其发芽指数最低仅为0.05,平均发芽开始时间长达22.3d,硬实率高达97.2%。再者,发芽前处理对于黄花棘豆发芽状况的效应亦受到温度条件的影响。温度为变温25℃/5℃时,冷水浸种可明显提高种子的发芽指数,缩短种子萌发的开始时间;温度为恒温10℃时,冷水浸种可提高种子发芽率。然而,其他温度条件下其种子发芽率、发芽指数、发芽开始时间及硬实率与对照均无明显差异。因此,对于高寒草甸年均温较低、昼夜温差大的情况,黄花棘豆依靠种子快速建立种群的机会较小。

Factors that Affect Seed Germination of Poisonous Grass-Oxytropis ochrocephala

To understand the germination characteristics of yellow-hair crazyweed (Oxytropis ochrocephala),different temperatures and pregermination treatments were conducted to study the factors that affect seed germination.The results showed that temperature was the most significant factor germination.From 10℃ to 25℃,seed germination rate increased with temperature,with the highest germination rate of 15.3％ in 25℃,and the lowest germination rate of 1.3％ in 10℃/5℃.Anyhow,germination rate was significantly higher under the condition of constant temperature than that of the corresponding treatments with low temperature in night.With temperature rising,the vigor index of yellow-hair crazyweed was also increased,and the initiatory time of seed germination was shortened and the hard seed rate was decreased.In 10℃/5℃,the vigor index was the lowest of 0.05,with the initiatory time of seed germination of 22.3 d and the hard rates of 97.2％.The influence of pregermination treatments on seed generation was related to temperature.In constant temperature of 25℃/5℃,seed vigor index was significantly improved under seed soaking in cold water,and it also shortened the initiatory time of seed germination;while the germination rate was significantly increased under seed soaking at variable temperature of 10℃.However,the seed germination rate,vigor index,initiatory time of seed germination and hard seed rate were at the same level in other temperatures.Thus,the yellow-hair crazyweed may have little opportunity of quick establishment in alpine grassland,where it has a lower average annual temperature and dramatic temperature fluctuations between days and nights.