干旱胁迫对决明种子萌发及幼苗生理特性的影响

为探明干旱胁迫对决明种子萌发、幼苗生长和生理生化特征的影响,采用聚乙二醇(PEG-6000)模拟不同程度的干旱胁迫,研究干旱胁迫下决明种子的发芽率、发芽指数、胚根及下胚轴长度、幼苗叶片的叶绿素质量分数、抗氧化酶活性和丙二醛(MDA)质量分数等指标的变化情况.研究表明:随着干旱胁迫强度的加强和胁迫时间的延长,决明种子的发芽率(Gr)、发芽指数(Gi)和活力指数(Vi)明显降低;幼苗胚根和下胚轴长度缩短;幼苗叶片叶绿素质量分数降低,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性出现先升后降的趋势,过氧化物酶(POD)活性在胁迫中期下降,后期又进一步升高,MDA质量分数呈现出持续上升的趋势.干旱胁迫对决明种子萌发和幼苗生长均有显著的抑制作用,但同时决明种子及幼苗也能通过自身一系列生物学与生理学指标的改变,主动适应干旱环境.

Effects of Drought Stress on Seed Germination and Physiological Characteristics of Cassia obtusifolia L. Seedlings

In order to explore the effects of drought stress on seed germination and seedling growth of Cassia obtusifolia L.and on its physiological and biochemical characteristics,drought stress was created with different concentrations of PEG-6000,and its germination rate,germination index,vigor index,radicle length,hypocotyl length,chlorophyll content,antioxidant enzyme activities and MDA content were recorded and analyzed.The results showed that with the strengthening of drought stress and extending of the stress time,seed germination rate,germination index and vigor index were significantly reduced,radicle length and hypocotyl length of the seedlings were shortened,the chlorophyll content of the leaves decreased,SOD and CAT activity first increased and then decreased,POD activity decreased in the interim and increased in the late time,and MDA content showed an upward trend.In conclusion,seed germination and seedling growth of C.obtusifolia were significantly inhibited by drought stress in this experiemnt,but the plant could also adapt to drought stress through its own biological and physiological changes.