Effect of Metabolites and Antioxidants on Freezing Tolerance of Lentil Genotypes Under Controlled Conditions

To study freezing tolerance (-13, -15 and -18°C) of 40 lentil (Lens culinaris Medik.) genotypes, a factorial experiment in completely randomized design was carried out at the Research Center of Plant Science, Ferdowsi University of Mashhad, Mashhad, Iran, in 2017-2018. Significant differences observed between genotypes for survival percentage after freezing stress and chlorophyll a, carotenoids, anthocyanins, soluble carbohydrates, proline, malondialdehyde (MDA), phenol, protein, DPPH, ascorbate peroxidase and peroxidase before freezing stress. Stepwise regression analysis showed that chlorophyll b had the most positive effect and protein, and MDA had the most negative effect on survival percentage. Cluster analysis grouped genotypes into five clusters. For most of the studied traits, genotypes in clusters 4 and 5 were greater than average of all genotypes as well as genotypes in other clusters. In clusters 4, anthocyanins, protein, MDA, phenol, proline, ascorbate peroxidase and peroxidase contents were higher than other clusters. Survival percentage, chlorophyll b, carotenoids, total pigments, and DPPH of cluster 5 were higher than the other clusters. Principal component analysis showed that MLC469, MLC458, MLC409, MLC74, MLC84, MLC169, MLC394, MLC95, MLC17, MLC163 and MLC303 for antioxidant capacity and metabolites, and MLC70, MLC410, MLC47, MLC31, MLC91, MLC8, MLC286, MLC407, MLC472, MLC61, MLC83 and MLC334 for photosynthetic pigment capacity were more suitable than the other genotypes. It can be concluded that these attributes are very important in predicting, before cold stress, the effect of cold stress on survival percentage of lentil genotypes.