A new morphological method to identify cold tolerance of melon at seedling stage

Abstract

Low temperature restrains the growth and development of melons, as well as severely impairing the yield and quality. To obtain a rapid and accurate method for evaluating cold tolerance of melon, 10 genotypes were selected to investigate their cold tolerance at seedling stage. Chilling stress (15°C/6°C, day/night) increased leaf angles and caused leaves wilted: the phenotypes of the 10 genotypes were obviously different. Thus, a new predicted method for chilling injury index (CII) of melon was constructed based on the change of leaf angle and leaf state. The CII showed significant correlation with survival rate, maximum photochemical quantum yield of PSII (Fv/Fm) and changes of SPAD value. Moreover, the validity of the method was further verified by seedlings growth, photosynthesis, membrane permeability and metabolites accumulation of four screened genotypes. Taken together, this work provides a morphological and accurate method for evaluating cold tolerance in melon.