Physiological and biochemical traits as indicators for cold tolerance in sugarcane (Saccharum species)

From sugarcane germplasm assemblage of 1200 genotypes, comprising interspecific introgression lines of genus Saccharum, advanced breeding lines, other research station varieties, S. barberi clones and S. spontaneum clones, consistent efforts were made to select the set of 24 cold tolerant genotypes and 24 cold sensitive genotypes. The selection was done on the basis of significant differences in chlorophyll content, Brix° content (total soluble sugars), leaf colour and bud necrosis before and after cold stress. These selected genotypes were extensively assessed for physiological and biochemical parameters viz., proline, chlorophyll, carotenoids, total soluble sugars, free amino acids and relative water content before and after the cold stress. Genotypes selected as cold sensitive showed significant decline in chlorophyll and carotenoids content, proline content, total soluble sugars and free amino acids in comparison to tolerant genotypes. Differential behaviour of physiological and biochemical parameters indicated that these parameters may serve as novel screening criteria for selecting tolerant and sensitive genotypes under cold stress. Identification of cold tolerant genotypes will serve as genetic stocks and pave the way for the development of crop cultivars tolerant to cold stress, which may stabilize crop production and extend its availability period. The study can serve as strong foundation to initiate breeding for cold tolerance in sugarcane.