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 3.87 U/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%).