Genotypic Variation Among Sorghum Cultivars for Seed Vigor, Salt and Drought Stresses
This study was conducted to determine genotypic variation among sorghum cultivars grown under similar ecological conditions for seed vigor, NaCl and drought stresses. A seedling survival test was also performed in a pod experiment to investigate genotypic differences in terms of sorghum drought tolerance. In seven sorghum cultivars, seed vigor was determined using electrical conductivity and accelerated aging tests, and germination rate and seedling growth of these cultivars were evaluated under salt (NaCl) and drought stress induced by PEG 6000 at water potentials of 0.0, 1.8, 3.6, 7.2 and 10.8 bar. The results showed that seed vigor differed among sorghum cultivars and the highest correlation coefficients were determined between laboratory emergence and accelerated aging (r=0.967**), and between germination and electrical conductivity (r=-0.873**). Electrical conductivity found a suitable test for determining germination potential of sorghum seed lots while the best method predicting emergence percentage was accelerated aging. Germination was delayed in both NaCl and PEG solutions. Germination, root length and shoot length were higher, whereas mean germination time was lower, in NaCl solution compared to in PEG solution at the same water potential. The most and least vigorous seeds were observed in the Akdarı and Gözde 80 cultivars, which displayed the lowest germination percentages in NaCl and PEG solutions. From this study, it could be concluded that seed vigor is not a reliable indicator of germination performance under salt and drought stress conditions and that genetic differences may play an important role in stress tolerance.