Identification Of Differences In Drought Resistance And Study Of Physiological And Ecological Characteristics For Different Tartary Buckwheat Cultivars

Fagopyrum tataricum not only has rich nutritional and medicinal values,but also has great physiological characteristics such as relatively high tolerance and strong adaptation ability to cold and barren conditions.There is a significant difference in resistance to drought stress among different genotypes of F.tararicum.Study of drought resistance characteristics of F.tataricum,screening of the materials of high tolerance genotypes and identification of indicators of drought resistance,and building a mathematic model for appraising the drought resistance not only can provide a foundation for evaluating the drought resistance and selection of genotypes,but also can provide a theoretical basis for germplasm breeding in cold areas of Loess Plateau.1 Comprehensive Evaluation and Indicators of the Drought Resistance of Different Genotypes of Fagopyrum tataricum at Seedling Stage:multiple indices of seedlings,including agronomic traits and physiological characteristics,were measured in the normal supply and drought stress with nine F.tataricum genotypes.Subordination function method,principal component analysis and clustering analysis were used to synthetically evaluate the drought resistance of different F.tataricum genotypes.Moreover,stepwise regression analysis was used to establish the optimal regression equation that could forecast and identify the drought resistance ability of.F tataricum.The result is as follows:?1?Drought stress has an obvious effect on the indexes of F.tataricum at seedling stage.Results of difference of testing indices showed that the overground index,root dry weight,root activity,root morphology index,soluble protein contents,relative water content,chlorophyll content and leaf fluorescence parameters under drought stress were obviously decreased compared with the control group.Compared with the control group,drought stress not only resulted in the decreases of aboveground and root characteristics,root activity,soluble protein contents,leaf relative water and chlorophyll content,Fm and Fv/Fm,but also resulted in the increase of the activities of superoxide dismutase?SOD?and peroxidase?POD?,the contents of malonaldehyde?MDA?and soluble sugar,and leaf Fo.Besides,the root-shoot ratio of drought tolerance genotypes showed a rising trend,while the intermediate and drought-intolerant genotypes showed a declining trend.?2?The principal component analysis turned 21 single indices into three independent comprehensive indices?accumulative contribution of 87.30%?.Nine F.tataricum genotypes were divided into three categories by clustering analysis:drought-tolerant type?DQ?XN9909 and QT?,middle type?GK1?QK6 and YQ1?,and drought-intolerant type?DY?HF1 and XQ1?.?3?In order to predict the drought resistance of each genotype and build a mathematical evaluation model,D values and drought tolerance index of various indexes were taken as the dependent variable and independent variable,respectively,for the stepwise regression analysis.By establishing an optimal regression equation,eight influential indices for drought resistance,including plant height,stem diameter,root-shoot ratio,root activity,main root length,MDA content,F_o,and leaf relative water content,were selected.The predictive values of drought tolerance of nine F.tataricum had a significantly correlation with D values?R2=0.988**?,which showed a certain accuracy and efficiency to forecast the F.tataricum drought-resistance by using this equation.And the identification work could become easier when measuring these indexes selectively.2.Effects of water on root Physiological characteristics at seedling stage and yield different tartary buckwheat:the effects of three different water stresses on the physiomorphological characteristics and root associated physiological characteristics of the tartary buckwheat?‘DiQing',‘Yunqiao1',and‘Duoyuan'?during the seedling stage were studied in a pot experiment.The results showed that:?1?With aggravation of water stress,Testing varietiess'seedling plant height,stem diameter,leaf area,shoot dry weight,total root volume,total root area,chlorophyll content,leaf relative water content and potential activity of PSII F_v/F₀ and the maximal photochemical efficiency of F_v/F_m,root activity and soluble protein content declined,but the drop is different,is shown as:Duoyuan>Yunqiao1>DiQing.?2?Root/shoot ratio,root SOD,POD activity,root MDA,Content of proline and soluble sugar with deepening of drought stress is on the rise,is shown as:DiQing>Yunqiao1>Duoyuan.Maximum root length under moderate stress has a trend of elongation,but three varieties were depressed at the influence of severe stress,and the depression of DiQing is most smallest.?3?With aggravation of water stress,branches of main stem?grains per plant?100-seed mass of tested varieties declined at mature stage,Grains per plant was most obvious.Analysis showed that,under the drought stress,whether the obvious morphological indices,root SOD,POD that scavenging free radical and yield at mature stage etc.,Pingqiao2all have a good performance,prominent superiority.In short,DiQing under drought stress has a stronger ability to adapt,worst drought resistance of Duoyuan,Yunqiao1 belong to the intermediate type.