Study On Water Saving And Drought Resistance Related Physiology Mechanisms And Genetic Characteristics Research Of Winter Wheat Zhongmai 895

As the high speed of popultion growth and the frequently increasing of extreme climate change,breeding water saving and drought resistance wheat varieties is an essential strategy to ensure food security and the efficient utilization of resources in our country.The main cultivar in Huang-Huai Rivers Valley Wheat Zone Zhongmai 895 of this research was used to investigate root system architecture at seedling stage,absorption and utilization efficiency of water and fertilizer in adult plants,stay green and drought resistance related physiological traits in late growth stage during the 2016-2017 and 2017-2018 cropping seasons.Dissecting the genetic basis of root system architecture t seedling stge,drought resistance related traits in the late growth stage in adult plant,mapping QTLs which have strong correlation with key traits.The result could provide the basis information for extension and breeding for new wheat varieties which are water and fertilizer efficient high yield and wide adaptability.The main results were as follows:1.Dissecting the genetic basis of root system,root architecture and biomass at seedling stage under different nitrogen(N)and phosphorus(P)treatments by using a double haploid(DH)lines derived from cross between Yangmai 16/Zhongmai 895 under hydroponic-based phenotyping pipeline.The results showed that,Zhongmai 895 performed excellent root morphology at seedling stage,and showed longer root length,root diameter and root surface area under high N and low P treatments,which were consistent with the expression of strong root vigor and efficient absorption of water and nutrients in the field.Nine root traits related to N and P were used to investigate QTLs by genetic map.59 QTLs regulated by N and 34 QTLs regulated by P were identified,among these,53 QTLs showed positive additive effects contributed by Zhongmai 895.6 new QTLs under low N treatments were located on 4BL(3),7DS and 7DL(2)chromosomes,related to shoot dry weight,root dry weight,total dry weight,root length,root volume and root surface area,accounting for 6.1 to 12.5%of the phenotypic variances,and the mapped QTLs under different N and P treatments could be used as new resources for improving seedling nitrogen and phosphorus use efficiency research.2.There were significant genetic differences between wheat varieties in response to water(W)and nitrogen(N)treatments and fertilizer requirement.In the different water and nitrogen treatments,study on water and fertilizer utilization efficiency,and yield potential by using Zhongmai895 and Aikang58.The results showed that,Zhongmai 895 had higher dry matter accumulation and thousand grain weight(TGW),strong ability of day matter translocation after anthesis,and more sensitive to high level water and fertilizer.The characteristics of high yield and high efficiency in Zhongmai 895 might be the basis of strong root system.Considering the economic benefits of Huang-Huai Rivers Valley Wheat Zone,we suggest that the recommended W condition amounts for Zhongmai 895 and Aikang 58 should be in 120mm.At the same content of phosphate and potash fertilizer,the recommended N application should be 180 kg·hm-2 for the basic N fertilizer or 120 kg·hm-2+60 kg·hm-2(at jointing stage).3.NDVI and chlorophyll content(Chl)both increased from flowering to late grain-filling stage,while the canopy temperature(CT)was increased among DH lines and parents.Correlation analysis showed that grain yield(GY)was positively correlated with NDVI and Chl,but negatively correlated with CT.Zhongmai 895 showed higher Chl and NDVI,maintained lower CT at mid-late stage,provided important guarantee for increasing grain filling process and delaying leaf senescence,which had stay green and high yield potential.4.25 stable QTLs were identified for stay green related traits in DH lines under two places four years.Among these,11,8 and 4 QTLs were related to NDVI,Chl and CT,accounting for 4.32 to 32.22%of the phenotypic variances.We analyzed the performance and genetic mechanism of DH lines based on the root traits and stay green related traits,showed that 4 loci were co-located.The loci related to root architecture(root diameter,root tip number)and root biomass(root dry weight,ratio of root to shoot)also associated with Chl,CT and NDVI in grain filling stage,had significant correlation with yield.5.DH lines with stay green function genes should combined higher chlorophyll content of top-three leaves,higer NDVI in mid-late grain filling stage(21 days postanthesis),lower CT in 7 days postanthesis,also have highly correlation with yield,and the stay green genes were contributed by Zhongmai 895.Principal component analysis results indicated 5 lines with stay green function genes and high yield potential,they were DH6046,DH6095,DH6093,DH6016 and DH6163.