Genetic variability for early seed vigor traits for enhanced performance under sub-optimum temperatures in sweet corn (Zea mays Convar. saccharata L.)

High germination and seed vigor under sub-optimum temperature is desirable for successful stand establishment in Sweet Corn. An investigation was undertaken to assess the performance of shrunken2 based Sweet Corn hybrids; CMVL Sweet Corn-1 and Pusa Super Sweet Corn-2 and their parental lines; SWT16, SWT17, VSL16 and VSL4 for early seed vigor parameters under sub-optimum (15°C, 20°C) and optimum (25°C) temperature conditions. Among the genotypes, hybrids (CMVL Sweet Corn-1 and Pusa Super Sweet Corn-2) were superior than their parental lines for the seed vigor traits like seedling emergence, germination index, mean germination time (MGT), vigor indices, root growth parameters and field emergence under sub-optimum temperature. The inbred lines; SWT16 and SWT17 had better performance than VSL16 and VSL4 for seed vigor parameters under sub-optimum temperatures. Seedling root architecture affected seedling performance and establishment under sub-optimum conditions. In the study, under sub-optimum temperatures seedling root parameters i.e. the root length, surface area and root volume reduced whereas the root diameter increased in the sweet corn lines. Vigor index-II (0.87 and 0.78) and MGT (-0.87and -0.54) showed significant correlation with the field emergence of sweet corn genotypes under 15 and 20°C respectively and thus could be the selection indices for identifying sweet corn genotypes with optimum performance under sub-optimum temperature regimes.