Screening And Identifying Of Telorant Genotype Fagopyrum Tataricum And The Mechanism Of Adapting To Low Phosphorus Stress Environment

In order to provide the theoretical basis for the breeding of Fagopyrum tataricum with high P-efficiency and the infertile soil cultivation on the Loess Plateau 14 F.tataricum were planted to get the low phosphorus tolerant genotype and explore their evaluation indicators within seeding and in sand culture,which was divided two phosphate supplying levels.Then,to explore the responses of F.tataricum to low phosphorus(P)stress,a potting experiment was conducted to examine the agronomic traits and physiological characters of two types of F.tataricum with known low phosphorus tolerance at the seedling stage under different P treatment.Third,in order to provide a theoretical basis for production practice,we explore the effect on the agronomic traits and physiological characters and yields of F.tataricum with increase of the phosphorus rate,a pot experiment was conducted.The main results are as follows:1.The results showed that under low-P stress,the shoots of all genotypes were more affected than roots.And specific performance: plant height,stem diameter,leaf area,dry weight of shoots and roots,average root diameter,root surface area,and root volume decreased for all different genotypes,whereas the length of the main root and most root-shoot ratios increased.To some extent,the amplification of different genotypes were significantly different;Low phosphorus stress also affected series of physiological indexes of F.tataricum.Chlorophyll content,soluble protein content,and root activity decreased,whereas root superoxide dismutase(SOD)activity,peroxidase(POD)activity,acid phosphatase activity,soluble sugar content,and free proline content all increased,and the increase was greater in low-P tolerant cultivars than that in low-P sensitive F.tataricum;Total P content and P accumulation per plant decreased,whereas P use efficiency increased.2.The principal component analysis divided the 22 individual indicators into 4mutually independent comprehensive indicators(cumulative contribution rate of90.06%);and cluster analysis divided 14 kinds of F.tataricum into three categories:low phosphorus tolerant,intermediate and phosphorus sensitive.In order to investigate the index of low-P tolerance of F.tataricum at a seedling stage,the optimal regression equation was established with the comprehensive evaluation value of low-P tolerance(D value)as the dependent variable and the low-P tolerance index of each indicator as the independent variables.Seven indicators of root surface area,root length,plant height,aboveground dry mass,acid phosphatase,phosphorus accumulation and POD activity were examined,which could be used for the rapid identification of low-P tolerance of F.tataricum at a seedling stage.3.A pot experiment results showed that the effects of different phosphorus application rates on agronomic traits,physiological indexes and yields of three species of F.tataricum were different.Under the conditions of this experiment,phosphorus application could significantly increase yields of low-P tolerance of three F.tataricum,but the amount of phosphorus applied to the highest yields of three varieties was different.The low-P tolerance variety `Diqing 1’ had the highest yields under the treatment of medium phosphorus(P3),while the low-P sensitive variety ’Xiqiao 1’ had the highest yields in high phosphorus(P4).The experiment showed that the yields of’Xiqiao 1’ did not rise first and then decrease within the range of phosphorus concentration.Although Xiqiao No.1 was not tolerant to low phosphorus,it was more tolerant to high phosphorus.Comparing the yields of different varieties,we could see that the yield of low-P sensitive variety ’Xiqiao 1’ was the highest at P4(high phosphorus),but it significantly lower than ’Diqing 1’ when phosphorus supply at P3(medium phosphorus),which indicated that ’Diqing 1’ has higher phosphorus utilization efficiency.In conclusion,to adapt to low-P environments,the low-P tolerant cultivars absorbed and utilized soil P by root growth and higher acid phosphatase,maintained stronger photosynthetic capacity by higher chlorophyll content,and reduced membrane lipid peroxidation damage by higher antioxidant enzyme(e.g.,SOD and POD)activity.Within a certain range,increasing phosphorus concentration was beneficial to the growth of F.tataricum,and the yield of low-P tolerant variety ’Diqing1’ and low-P sensitive variety ’Xiqiao 1’ was the highest at the concentration of P3 and P4,respectively.Optimizing low phosphorus tolerant varieties of F.tataricum and applying phosphorus fertilizer appropriately are the best strategies to solve the problem of phosphorus deficiency in the Loess Plateau,especially in thenewly-created areas of the Loess Plateau.