Genotypic differences in salt tolerance from germination to seedling stage in peanut

Abstract

Aims In the present study, the degree of salt tolerance in different peanut varieties/lines was investigated from emergence to seedling stage. Methods The seeds of peanut varieties/lines were planted in pots with salt levels of 0, 0.15%, 0.30%, and 0.45% NaCl in soils. The degree of salinity tolerance was systematically evaluated according to ten indices reflecting emergence, morphology, and biomass accumulation, etc. Important findings Statistic analysis for the 10 indices, including the relative emergence time, relative plant height, relative stem height, relative taproot length, relative shoot fresh mass, relative root fresh mass, relative shoot dry mass, relative root dry mass, and relative plant dry mass, showed large variations among the 107 varie- ties/lines; each index displayed a normal distribution under different salt stresses. Using the principal component analysis, the ten indices could be categorized into several independent factors. According to the total score, the 107 varieties/lines were divided into four groups, i.e., highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible, by cluster analysis at salt level of 0.15%, 0.30%, and 0.45%, respectively. The 107 varieties/lines accounted for 29.0%, 39.0%, 27.5%, and 4.5%, respectively under salt level of 0.15%, and 5.5%, 34.5%, 23.5%, and 29.0%, respectively under salt level of 0.30%, in the highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible groups. The salt tolerance in some varieties/lines varied with the level of salt stresses; some varieties/lines showed tolerance under low salt stress but susceptible under high salt stress. The number of varie- ties/lines showed the same tolerance or susceptibility under different salt stresses was 1 ('Fuhua 11'), 7 ('Huayu 28', 'Z11', 'Huayu 39', 'Huayu 32', 'HLN2', 'Yueyou 26', and 'XE019'), 0 and 1 ('D1035'), respectively, in the highly salt tolerant, salt tolerant, salt susceptible, and highly salt susceptible groups. The 10 indices reflecting emergence, morphology, and biomass accumulation, etc., differed significantly or highly significantly among the varieties/lines in the four groups. Compared to the salt tolerant groups, the salt susceptible groups had prolonged