Evaluation Index System Of Salt Tolerance Of Rice And Comprehensive Evaluation Of Salt Tolerance

In this study,30 different rice(Oryza.sativa L.)varieties(lines)were treated in the salt(NaCI)concentrations of 0%(ck),0.4%,0.6%,0.8%,and 1.0%were determined during the germination period.From the seedling stage to the maturity stage,artificial salt pools were used to set salt stress treatments with NaCI concentrations of 0%(CK),0.3%and 0.5%,respectively.The germination rate,root length,shoot length,photosynthetic rate,dry weight,malondialdehyde content,proline and soluble sugar content were measured and measured during germination and seedling stage after 20 days of salt stress treatment.Physiological and biochemical indicators such as substance and peroxidase(POD)activity and related indicators of plant height,ear length,panicle number,real grain number,and number of empty grain.By using salt tolerance coefficient method,correlation analysis,principal component analysis and kinetic function method,the correlation analysis and evaluation of salt tolerance index and salt tolerance of 30 rice cultivars(lines)at different growth stages were carried out.Finally,The stepwise regression analysis was used to screen the salt tolerance evaluation indices,and the salt tolerance of rice during the whole growth period was comprehensively evaluated.The method and theory of salt tolerance identification and evaluation,salt tolerance germplasm screening and salt tolerance breeding were provided.In the germination stage of rice,this study calculated the indices of germination potential,germination rate and germination index of 30 rice varieties(lines).The results showed that different salt concentration treatments could inhibit the germination of rice,and the salt tolerance coefficient of each index among the varieties(lines)was inconsistent.The single indicator could not determine the salt tolerance of the varieties.The results showed that the salt tolerance correlation analysis and evaluation of rice varieties(lines)were better to the conducted the at 0.8%salt concentration.At 0.8%salt concentration,the root length was significantly correlated with the number of roots,and other parameters.In the rice seedling stage,the study determined and calculated the net photosynthetic rate(Pn),water use efficiency(WUE),above-ground dry weight(DW)and fresh weight(FW)of 30 rice varieties(lines).The results showed that the net photosynthetic rate(Pn),water use efficiency(WUE),aerial fresh weight(FW),aboveground dry weight(DW)and chlorophyll content(TC)of rice varieties(lines)under different salt stress conditions both showed a decrease,while malondialdehyde content(MDA),soluble sugar content(SS),soluble protein content(SP),proline content(Pro),and peroxidase activity(POD)showed an increase.Changes in rice varieties(lines)at different salt concentrations were inconsistent.The results showed that the salt tolerance of the seedling stage with 0.5%salt concentration was better,and there were significant correlations among other indicators except the soluble protein content(SS)and proline content(Pro).At the maturity stage of rice,the salt tolerance index of the indexes of plant height,ear length,number of panicles per plant,number of solid grains and 1000-grain weight of 30 rice cultivars(lines)was determined and calculated.The results showed that salt stress reduced the index value of rice maturity,and the comprehensive evaluation of different indexes of rice maturity was better with 0.5%salt concentration.Considering the importance of yield per plant,stepwise regression analysis was carried out with the yield per plant as the dependent variable.It was found that the economic coefficient of rice and the number of panicles per plant were two indicators that significantly affected rice yield.During the maturity of rice,there were significant degrees of significant correlation between the indicators.Then statistical analysis and salt tolerance rankings were performed for each period.The salt tolerance coefficient of the salt tolerance evaluation index of each growth period of rice was inconsistent under different salt concentration conditions,and the single evaluation index could not reach the consistent conclusion of salt tolerance.However,the germination rate,salt damage rate,germination index,vigor index and other indicators in germination period were significantly correlated with the yield per plant at maturity>Pn、WUE、DW、TC showed a significant positive correlation with yield per plant at maturity.For the screening of salt tolerance index in the whole growth period,the regression equation using stepwise regression analysis and the estimation accuracy are over 90%.In this study,the germination rate,bud length,vigor index,germination potential,WUE、Pn、FW、yield per plant,1000-grain weight,seed setting rate,plant height and other indicators participate in the comprehensive evaluation of salt tolerance in the whole growth period,using principal component analysis,membership function and other methods to obtain D value,and finally The test materials were classified into three types:salt-tolerant,medium salt-tolerant and salt-sensitive by system clustering.In this study,the significance of different salt tolerance evaluation indexes in salt tolerance analysis and evaluation of 30 rice varieties(lines)with different salt tolerance were analyzed under different growth stages and different salt concentrations.There is no consistency between the salt tolerance of rice varieties under different growth stages and different salt concentrations.During the same growth period,the salt tolerance coefficient is different between different evaluation indexes at specific concentrations,but there are different degrees between different indicators.Correlation;under the specific salt concentration,although the salt tolerance index of rice in different periods is different,there are also different degrees of correlation between the indicators.Using the relevant information of these different evaluation indicators,the salt tolerance of rice can be well evaluated.