Lentil genotypes Selection for freezing tolerance by fluorescence chlorophyll

The experiment was conducted as a factorial base on completely randomized design with three replications under controlled conditions at Ferdowsi University of Mashhad in 2018. 20 lentil genotypes, three freezing temperatures (0, -18 and -20°C) and six time point (before stress, 12, 24, 48, 72 and 96 hours after stress) were investigated. Decrease the temperature from 0 to -18 and -20°C reduced the maximum efficiency of PSII photochemistry in the light (F'v/F'm). The lowest values of F'v/F'm were observed at -18 and -20°C, 12 and 24 hours after stress, respectively. Then F′v/F′m gradually increased over time. However, at -20°C, the F′v/F′m did not reach the initial value before stress. PSII operating efficiency in the light adapted leaf (F′q/F′m) was reduced by decreased temperature in all genotypes and all time point. Despite the initial decrease in F′q/F′m, most of the studied genotypes, had a good ability to recover at temperatures of 0 and -18°C. The results of cluster analysis and principal component analysis (PCA) showed that the second component include survival percentage, dry weight, F'v, F′q/F′m and F′v/F′m explains 20.76%. Most genotypes belonging to the second group including MLC11, MLC286, MLC407 and MLC469 are in this component. Due to the 100% survival of these genotypes at -18°C and their suitable potential for recovery of chlorophyll fluorescence components and regrowth, their use is recommended for additional studies for autumn cultivation in cold regions.