土壤含水量对狗牙根叶片生理生态指标的影响

采用盆栽控水试验，研究了不同土壤含水量（水淹，23%，18%，13%，8%）对我国雅砻江库区重要植物物种狗牙根叶片光合色素、SOD活性、POD活性、脯氨酸和MDA含量变化的影响。结果表明:与对照（23%）相比，狗牙根受到淹水胁迫时叶绿素a，b的含量和光合效率有所下降，丙二醛含量有所升高，但是抗氧化酶活性以及脯氨酸含量的增大提高了植物对淹水胁迫的抵抗力。随着土壤含水量的减少，叶绿素a和b的含量、光合速率、SOD、POD活性和丙二醛含量先升高，随后逐渐降低。SOD和POD活性在8%时存在最低值，分别为33.10U/gFW和3.87U/gFW。Carotenoid/Chlorophyll（Car/Chl）比值在18%时达到最低值0.22，然后增大。脯氨酸（Pro）含量随胁迫程度呈明显的增大趋势，并在8%达到最大值0.31μg/gFW，说明干旱条件时狗牙根通过提高类胡萝卜素和脯氨酸含量来改善渗透调节能力，增强对干旱胁迫的抵抗能力和适应力。但严重的干旱胁迫（8%）导致了植物叶片的损伤。

Effects of Soil Water Contents on the Ecophysiological Characteristics of Bermuda Grass Leaves

The activities of superoxide dismutase (SOD) and peroxidase (POD),contents of photosynthetic pigment,proline (Pro) and malondialdehyde (MDA) in the leaves of Bermuda grass were studied at five soil water contents (flooding,23%,18%,13%,8%,respectively).The results showed that under flooding stress,the contents of chlorophyll a (Chla),chlorophyll b (Chlb) and the photosynthesis rate decreased,antioxidant enzyme activity and the proline content increased compared to control (23%).The contents of chlorophyll a (Chla),chlorophyll b (Chlb) and the photosynthesis rate increased firstly and then declined with the decreasing soil water contents,while Carotenoid/Chlorophyll (Car/Chl) declined to 0.22 at 18% and then increased under medium and serious drought.The minimum activities,33.10 U/gFW for SOD and 3.87U/gFW for POD,existed at soil water content of 8%.The MDA content also gradually increased and then declined,whereas the proline (Pro) content increased steadily.These results indicated that the increased antioxidant enzyme activities and proline (Pro) content enhanced the resistant potential of Bermuda grass for flooding and drought,and increased contents of carotenoid and proline (Pro) which resisted membrane-lipid peroxidation,improved the osmotic potential and enhanced the adaptability of Bermuda grass.However,injuries on the leaves were induced by the hard drought stress (8%).