Morphological Characterization and Germination-Based Screening for Cold Stress Response of Vigna radiata L.

Aims: Morphological characterization and germination based screening for cold stress response of  Vigna radiata, was performed to identify the cold resistant genotypes. 
Methodology: Augmented design experiment was performed to characterize 204 mungbean genotypes under field condition based on 24 DUS characterization. A germination-based screening at 10°C was performed in a total of 204 germplasms in a plant growth chamber to identify the cold responsive genotypes. Seeds were soaked in water for 6h in the dark under normal temperature and imposed cold stress (100C) for 2, 4, 6, 8 days and further transferred to control temperature  (220C) for  recovery. 
Results: On the basis of the 24 DUS characterizations of 204 mungbean genotypes are classified into three major clusters.  Highest number of genotypes in cluster I (113 genotypes), followed by 81 genotypes in cluster II and least number (10) of genotypes in cluster III. Based on cold stress study  and biplot analysis showed that germination percentage, germination rate index, Timson’s index, mean germination time and coefficient of velocity of germination to be more influential and  categorized into three groups having 11 genotypes are resistant, 135 genotypes are susceptible, and 58 genotypes are intermediate.  Biochemical analysis showed that the tolerant genotype having increased chlorophyll, carotenoid and MDA content and oxidative enzyme activity as compared with susceptible and intermediate genotypes under cold stress.  
Conclusion: The present study identified 11 genotypes having cold resistant and may be used for breeding program.