Effects of High Temperature Aging on Germination and Physiological Characteristics of Different Cotton Varieties

The germination index, activity, and electrical conductivity of seeds and the levels of POD, SOD and MDA content in hypocotyls of seedling were studied with four cotton varieties (Jinmian 21, Jinmian 32, Jinmian 34, Tai 91995) treated with high temperature and high humidity. The result showed that, in the closed circumstance of high temperature(45±1)℃ and high humidity (RH 100%), seed germination and activity of four cotton varieties raised at the beginning, then dropped off, but seed electrical conductivity increased gradually as the treating time went on. The changes of POD and SOD activities in hypocotyls took a double-peak-curve pattern, but the activity of POD had an ascendant trend and changed much widely than that of SOD along with the aging time extension. At 48 h of aging treatment, the activities of POD in seedling hypocotyls of Jinmian 21, Jinmian 32, Jinmian 34, and Tai 91995 increased 151.3%, (50.2%), 60.5%, 145.5%, more than that of controls respectively. The change of MDA content was influenced by the activities of POD and SOD, and negatively correlated to the activity of POD significantly.