Physiological characteristics and response mechanisms of different drought-resistant rapeseed varieties under PEG stress
[Purpose]To compare four different drought-resistant rapeseed varieties under drought stress using physiological indi-ces,to further elucidate the physiological mechanism of drought resistance in rapeseed.[Method]Four different varieties of rape-seed with different drought resistance were subjected to simulated drought stress with polyethylene glycol(PEG-6000)at a mass fraction of 5％and treated with an equal amount of distilled water as control(CK).The effects of drought stress on growth and de-velopment,antioxidant enzyme activity,and the osmotic-regulating substances of rapeseed seedlings were analyzed using petri dish experiments.[Result]Rapeseed growth and development were inhibited under drought stress.Compared with CK,the germination rate and vigor of strongly drought-resistant varieties(Qingza 4 and Zheyouza 1)showed no significant changes,while those of the weakly drought-resistant varieties(Xinyou 25 and Nongjia Ziyong 22)significantly decreased compared to the CK treatment.In ad-dition,the antioxidant enzyme activities(SOD,POD,CAT,and APX)of strongly drought-resistant varieties were significantly higher than those of weakly drought-resistant varieties.Under drought stress,the contents of hydrogen peroxide,superoxide anion,and MDA as well as conductivity were significantly lower in strongly drought-resistant varieties than those in weakly drought-resistant varieties,while the soluble sugar content in strongly drought-resistant varieties was significantly higher than that in weakly drought-resistant varieties.[Conclusion]Under drought stress,the difference between strongly and weakly drought-resistant varieties was due to the stronger ROS scavenging ability of the antioxidant system and higher levels of positive hormones and osmotic regulatory substances in the strongly drought-resistant varieties.This physiological mechanism enhances drought resistance in rapeseed seedlings.
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