Rapeseed Stress Tolerance And Yield And Agronomy Association Analysis Of Traits

Rapeseed is the most important oil crop in China,and its output accounts for more than 50% of domestic oil crops.It has great development potential in idle winter field and plays an irreplaceable role in edible vegetable oil field in China.In recent years,the country has been increasing the development of rapeseed industry through various policy support,and rapeseed has gradually become an important crop in the current national expansion of oil crops.With the continuous occurrence of extreme climate,rapeseed damage occurs more and more frequently,which has a serious impact on the yield.Previous studies mainly focused on the effect of rainy logging on rapeseed yield at flowering stage,while the effect of rainy logging at sowing stage on rapeseed yield is still in a blank stage.In this paper,based on the results of national rapeseed variety area trial,the rapeseed yield changes between rainy year and normal year,the changes of yield-related traits,the relationship between variety damage tolerance and yield,and the response changes of variety yield composition to rainy waterlogging damage during planting period were analyzed by using multiple regression.The results of this study will provide theoretical and practical guidance for the scientific prevention of rain damage in autumn and for the improvement of the waterproofing resistant varieties.The main results of this study are as follows:1.In 2020,the planting period of rapeseed was affected by rain,which resulted in a large regional reduction in rapeseed production,with direct and indirect losses as high as 21%.The main climatic factors that lead to the decrease in output are the spatio-temporal variations of precipitation and autumn temperature,including more precipitation in October,less precipitation in January,and lower average temperature in October and November.Compared with normal years,more precipitation led to delayed sowing date of rapeseed,slow development of rapeseed,difficult to form strong seedlings,the number of effective corner fruit per plant and harvest density decreased significantly in the later period.In view of the waterlogging disaster caused by continuous rain in autumn,the selection criteria of watering-resistant varieties should be optimized,and the new varieties of rapeseed with high oil production and watering-resistant index in both normal and disaster years should be comprehensively screened.In cultivation,the early sowing should be timely and the planting density should be appropriately increased,which is conducive to reducing disaster losses.2.In 2020/2021,compared with 2019/2020,the contents of erucic acid and glucosinose were not significantly affected by rain damage,and all varieties reached the national double low rapeseed standard.The difference of oil content of rapeseed was not significant,because the overall oil production of rapeseed was reduced after the disaster.In addition,there were great differences in the adaptability of different varieties to waterlogging environment.The adaptability of 4,9zy YP27 and H1951 to waterlogging environment was strong and lodging resistance had no obvious change.The adaptability of 9zy YP12,Qinyou1919,Zhongyou510 and Huayouza12 to waterlogging was poor and lodging resistance decreased significantly.The disease incidence and disease index of sclerotinia sclerotinia of rapeseed varieties did not change significantly.From the perspective of comprehensive production,2019/2020 and 2020/2021 were both years with low incidence of sclerotinia sclerotinia.3.Identification results of rapeseed resistance at germination stage showed that fresh weight,root length and seedling rate of rapeseed would decrease significantly,and comprehensive analysis of rapeseed resistance at germination stage and yield traits under waterlogging found that the correlation between rapeseed resistance at germination stage and yield shape would change significantly before and after waterlogging.The growth of underground part will be promoted in a short time during the germination period of rapeseed.The yield and its composition with yield traits also changed significantly after waterlogging.Effective branch number,corner number and yield per plant had a very significant positive effect on the per mu yield of rapeseed,while the 1000-grain weight had a very significant negative effect.4.Multiple regression results showed that the changes of effective branch number per plant,effective corner fruit number per plant,yield per plant,growth period and sclerotium disease incidence had significant effects on the yield of rapeseed after raininization in October 2020.Further path analysis showed that rain damage affected the yield of rapeseed plant mainly by changing the number of corner fruit per plant,branch number and plant height,and combined with secondary disasters such as sclerotinia disease caused by waterlogging.By breeding rapeseed varieties with more effective number of corner fruit per plant,good yield per plant and stable growth period,it can prevent and resist disaster in the year of waterlogging.