Identification And Selection Of High Temperature Resistant Parents In Cotton

Yangtze Plain is one of the major cotton producing areas in China.In recent years,due to the rising of global temperature,the economic losses of crops caused by high temperature stress have become more serious.Therefore,it is of great practical significance to screen high temperature resistant cotton germplasm resources,clarify the relationship between different agronomic traits,physiological characteristics and high temperature tolerance,establish high temperature resistant screening index,and cultivate high temperature resistant varieties,effects of decreasing high temperature stress on stability and adaptability of cotton varieties.In this study,30 cotton germplasms were used to study the effects of high temperature on the growth,physiological and biochemical characteristics and agronomic traits of cotton,the high temperature resistant cotton parent material was selected.Suitable varieties for cotton production in the Yangtze Plain region.The main findings are as follows:(1)At 35?,40? and 42?,the germination rate decreased with the increase of temperature.This indicated that high temperature above 35 ? could reduce the germination rate of cotton varieties.(2)There were significant differences in plant height,leaf area and fresh weight among different cotton varieties at high temperature above 35 ?,among which CJ1831067,CJ1831068,Cj1831075,CJ1831076 and CJ1831086 were at relatively high level,c J1831053,CJ1831054,CJ1831055,CJ1831056,CJ1831059,CJ1831060,CJ1831072,CJ1831078,CJ1831079 were at relatively low level.(3)When the temperature of cotton seedling was above 35?,the activities of POD,photosynthetic characteristics and other physiological and biochemical indexes of different cotton varieties were significantly different.Among them,CJ1831067,CJ1831069,CJ1831074,CJ1831076 and CJ1831086 were the cotton varieties with high activity of antioxidant enzyme POD.(4)When the temperature was 40 ?,the flowering number of different cotton varieties had significant difference.Under high temperature treatment,some varieties of cotton appear anther not DEHISCENCE,not scattered pollen,pollen less,affect pollination and fertilization process,resulting in cotton buds and bolls fall off,reduce yield.(5)When cotton was subjected to high temperature stress,the yield of different cotton varieties showed significant difference.The abscission rate of buds and Bolls and the number of Bolls in the high temperature treatment group were significantly lower than those in the control group,and the Boll weight per plant was significantly higher than that in the control group.