| Non-heading Chinese cabbage(Brassica campestris ssp.chinensis Makino)belongs to Brassica,as an important leafy vegetable,it plays a significant role in vegetable industry of China.There are over 30%multiple-cropping areas of all vegetable multiple-cropping areas in middle-and-lower of Yangtze River.Its yield was influenced by many complex factors,especially the high temperatures in summer and fall season,which can reduce the yield widely.Therefor,it is very useful to breeding heat-resistant varieties of non-heading Chinese cabbage.In this study,we chose 10 relative heat-resistant varieties of non-heading Chinese cabbage as materials,based on the protected cultivation test,compared the differences of their agronomic traits,evaluated comprehensively their heat resistance and disease resistance,and also made correlation analysis for yield and resistance.This study can provide theoretical basis and practical experience for identification of heat-resistant varieties of non-heading Chinese cabbage.The results are as follows:When the seeding age was 28 days,there were significant differences in agronomic traits of different varieties.The range of plant height was 4.95?16.70 cm,the range of plant spreading was 11.10?20.15 cm,the range of leaf weight was 6.73?22.17 g,and the range of petiole weight was 6.24?34.49 g.Based on these results,we can take together the excellent traits by hybrid breeding and got new varieties which both had optimization phenotypes and heat-resistance.For yield test,there were 9 varieties higher than control,the range of the added yield was 5.63%?99.51%.Among them,the varieties of 1401,1402,1410and1411 had increased extremely.By correlation analysis,there were significant positive relationship between yield and plant height(0.785**),plant spreading(0.688*),weight per plant(0.938**),leaf length(0.774**),leaf weight(0.624*)and petiole weight(0.811**).Then we established an equation by multiple stepwise regression method for all these traits:Y=1103.79+41.73X1-28.31X2+23.94X3-96.35X5-62.37X7+6.05X8+181.98X11.According to the equation,the sequence of direct path coefficient between yield and plant height,plant width,plant weight,leaf length,leaf weight,stem length,stem weight were:0.161,0.333,0.87,0.035,0.135,0.132.the direct path coefficient of plant width,plant weight,play an important role on yield.For heat resistance and disease resistance test,there were 8 varieties reached to high resistance level for anthracnose,all of the varieties showed resistance for virus disease,and 7 varieties showed extremely resistance for heat resistance.By correlation analysis,the incidence of anthracnose and the incidence of virus disease showed significant positive relationship(r=0.971**),and the incidence of virus disease also had a significant positive relationship(r=0.913**)with heat injury.These results implying that heat injury of high temperature reduced the resistance of plant,in other words,heat injury induced more disease injury.Heat injury disease injury constituted a combination-injury,resulted in serious injuries.For nutritional quality test,the content of protein in leaf was higher than that in petiole in 10 varieties,so did the content of nitrate.The soluble sugar in different parts and different varieties also showed different content.There were no significant differences among 10 varieties for cellulose content,at the range of 7.403?8.712%.by correlation analysis between nutritional quality and resistance,the content of protein in petiole showed a significant positive relationship with resistance. |
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