Comprehensive evaluation of northern japonica rice saline-alkaline tolerance at seedling stage based on nonlinear principal component analysis

【Objective】 To identify saline-alkaline tolerance during seedling stage of northern japonica rice germplasm resources and screen suitable indicators for salinity tolerance identification, so as to provide reference for the breeding and cultivation of saline-alkaline-tolerant northern japonica rice.【Method】 The non-linear logarithmic principal component evaluation method was used to evaluate the saline-alkaline stress of rice seedlings, and saline-alkaline tolerance of 56 northern japonica rice germplasm resources were comprehensively evaluated for in terms of morphological characteristics, material accumulation and physiological traits taking 13 traits of rice seedlings as indicators.【Result】 The logarithmic principal component analysis was used to transform the saline-alkaline tolerance coefficients of the 13 indicators into 5 mutually independent comprehensive indicators with a cumulative contribution of 86.368%. The 56 materials were classified into 5 categories according to the comprehensive evaluation value of saline-alkaline tolerance Sf:extremely saline-alkaline tolerant, strongly saline-alkaline tolerant, mediumly saline-alkaline tolerant, mediumly saline-alkaline-sensitive and saline-alkaline-sensitive. LJ29, NF13G280, CB9 and LJ46 were extremely saline-alkaline-tole-rant, accounting for 7.1% of the total number of materials. The plant height(PH), above-ground part fresh weight per 100 plants(FWS) and above-ground part dry weight per 100 plants(DWS) were selected by gray correlation analysis as indicators for classifying saline-alkaline tolerance at seedling stage of the rice since the correlation coefficient between saline-alkaline tolerance coefficient and comprehensive value of saline-alkaline tolerance was greater than 0.5.【Conclusion】 Four extremely saline-alkaline tolerant materials, LJ29, NF13G280, CB9 and LJ46 are selected from the 56 northen japonica rice germplasm materials. Three suitable indicators for classifying saline-alkaline tolerance at seedling stage of the rice, plant height, above-ground part fresh weight per 100 plants and above-ground part dry weight per 100 plants are selected from 13 indicators, this statistical method is appropriate for classifying saline-alkaline tolerance of northern japonica rice at seedling stage.