Drought Resistance Evaluation And Screening Of Drought Tolerant Varieties Of Forage Oat Germplasm

Drought has long restricted the development of farming in Ningxia region,and selecting productive and drought-tolerant forage and oat types is one of the most economical and feasible methods to improve the quality and productivity of forage.In this paper,26 oat germplasm materials were used to simulate drought stress with high osmotic solution PEG-6000,and the germination characteristics of seeds of different oat varieties and their drought resistance were comparatively analyzed.The water use,photosynthesis,osmoregulation and other physiological and biochemical responses of different oat varieties in seedling stage under drought stress conditions and their inter-varietal differences were investigated through indoor potted water control tests,and the main effective drought resistance indexes were screened by using principal component analysis.The drought resistance of 26 oat germplasm materials was evaluated and graded using cluster analysis and affiliation function,and the drought and water-saving germplasm materials were selected to provide experimental reference for the selection and breeding of high-quality oat varieties.The main findings are as follows.(1)During the seed germination period,the germination rate,germination potential,shoot length,root length and seed vigor index of all oat materials decreased significantly with the increase of PEG6000 solution concentration,and the differences between different varieties were significant.The low concentration of PEG-6000 solution concentration could promote the germination of oat seeds.After principal component analysis,germination potential,germination index and vigor index were the main effect indicators for the evaluation of drought tolerance of oat germplasm.Through comprehensive evaluation,four drought tolerance levels were determined for seed germination of 26 oat materials,among which,,HF,SX and XYUN were strong drought tolerant varieties(level 1),and ML and DFW were medium drought tolerant varieties(level 2);TY2,TZZ,BY7,QHTY,TY70,MLS,JKTY,HW,DD,MNK,BY3,KLW,TYM,SZW,YM444 are weakly drought resistant varieties(level 3);YC,FY1,XYUE,QT1,TY1,SHOOT are not drought resistant varieties(level 4).(2)At the seedling stage,drought stress had significant effects on the growth and developmental characteristics and various indexes of all oat materials,among which,plant height decreased,tiller number and leaf area decreased,root length,root surface area and root volume decreased,above-and belowground biomass decreased to different degrees,and root-to-crown ratio increased relatively.Compared with other materials,the growth performance indexes of HF,SX,TY2 and BY7 were less affected by drought stress and maintained a certain biomass and strong drought resistance.(3)At the seedling stage,drought stress significantly affected the water use and photosynthetic physiological characteristics of all oat materials.Compared with CK,leaf water content,leaf relative water content,water potential,and K+content of oats decreased under drought stress.the values of MDA,starch,PRO,soluble sugar,and δ13C all increased significantly.Among photosynthetic physiological indicators,stomatal conductance,transpiration rate,net photosynthetic rate,and intercellular CO2 concentration showed different degrees of decrease,instantaneous water use efficiency,and long-time water use efficiency increased.Compared with the other materials,the photosynthetic rate of MLS,XYUN,HF and SX showed less reduction,higher water use efficiency and better water retention capacity.(4)The results of principal component analysis indicated that among all the tested indicators in seedling stage,12 indicators,including root area,root length,root volume,stomatal conductance,transpiration rate,net photosynthetic rate,free proline,soluble sugar and starch content,could be preferentially selected as the main effect indicators for comprehensive evaluation of drought resistance in oat seedling stage.The drought resistance of the 26 oat germplasm materials could be classified into three types through comprehensive evaluation,i.e.,strong drought resistance,medium drought resistance,and weak drought resistance.HF,SX and XYUN were strong drought resistance types.TYMQ,MLS,BY3,TZZ,BY7,SHOOT,TY1,ML,YC,and TY70 are medium drought resistant varieties.Imported sweet oats,DD,TY2,TYM,HW,KLW,TY1,SZW,MNK,YM444,XYUE,FY1,DFW DD,TY2,TYM,HW,KLW,TY1,SZW,MNK,YM444,XYUE,FY1,DFW are weakly drought-resistant type.Among them,HF,SX and XYUN have good overall performance in seed germination and seedling stage,with strong drought resistance and suitable for planting and production in arid-semi-arid water scarce areas.