Screening and evaluation of salt and alkali tolerance of rice at tillering stage in cold regions

【Objective】Screening indicators related to the salt and alkali tolerance of rice, screening and evaluating the salt and alkali tolerance of rice germplasm resources in cold regions, to provide theoretical basis for the selection of excellent salt and alkali tolerance rice varieties.【Method】The 17 rice varieties that were selected at the seedling stage to be salt-tolerant were selected as the research objects.Soda saline soil(salt-alkali stress) and meadow chernozem soil(control) were used for pot planting, and the rice was investigated at the tillering stage.Ten indicators such as root length, root surface area, root volume, root diameter, root tip number, root dry weight, stem number, plant height, leaf area, and ground dry weight were measured.Principal component analysis, cluster analysis, correlation analysis, BP neural network and regression analysis wereused to verify its rationality.【Result】Alkaline tolerance coefficient ranged from 0.19 to 1.00 for 10 morphological indexes of 17 materials under saline-alkali stress, with an average value of 0.68.The principal component analysis method was used to transform 10 individual indicators under saline-alkali stress into 3 independent comprehensive indicators, and the cumulative contribution rate reached 85.44%.The calculated comprehensive salt-alkali resistance value(D value) was obtained by calculating the membership function value and weight, and then the comprehensive salt-alkali resistance of the test materials was sorted from strong to weak according to D value.L14(Songjing 18) > L15(Songjing 24) > L12(Longjing 48) > L17(Baijing 1) > L06(Kongyu 131) > L05(Kenjing 8) > L03(Suijing 21) > L16(Dongdao 4) > L09(Longjing 42) > L11(Suijing 17) > L10(Longdao 9) > L13(Longjing 27) > L02(Yingdao 2) > L07(Song 98-131) > L08(Dongnong 428) > L01(Qijing 10) > L04(Changbai 9).The 17 materials were divided into four categories by cluster analysis, group 1 was variety with the strongest salt-alkali resistance and only contained Songjing 18;group 2 was salt-alkali resistant type and contained Kenjing 8, Kongyu 131, Baijing 1, Longjing 48 and Longjing 24;group 3 was sensitive type contained Suijing 21, Longjing 42, Dongdao 4 and Suijing 17;group 4 was highly sensitive type contained Qijing 10, Changbai 9, Yingdao 2, Song 98-131, Longjing 27, Longdao 9 and Dongnong 428.Based on the correlation analysis results of the indexes on the comprehensive salt-tolerant value, as well as the verification of its suitability by regression analysis and BP neural network, six indexes of root length, root surface area, root volume, root tip number, root dry weight and stem number could be indexes for evaluating the salt and alkali tolerance of rice at tillering stage.【Conclusion】Songjing 18 is a germplasm resource with strong salt-alkali tolerance among the 17 tested materials.The six indicators of root length, root surface area, root volume, root tip number, root dry weight and stem number can be used as salt-alkali tolerance evaluation indexes for rice at tillering stage in cold regions.