Determination of Genotypic Variation among Sorghum Cultivars for Seed Vigor, Salt and Drought Stresse

This study was conducted to determine genotypic variation among sorghum cultivars grown under similar ecological conditions for seed vigor, salt (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 ageing tests. Also, germination rate and seedling growth of these cultivars were evaluated under salt and drought stress induced by PEG 6000 at water potentials of 0.0 (distilled water), -1.8, -3.6, -7.2 and -10.8 bar. The results showed that there was a significant difference in seed vigor of sorghum cultivars grown at same ecological conditions. Akdari produced more vigorous seeds than the other cultivars. The significant relationship between accelerated ageing and laboratory emergence (r= 0.967**), and between electrical conductivity and germination percentage (r= -0.873**) were determined. The suitable tests for germination and emergence potential in sorghum were electrical conductivity and accelerated ageing, respectively. Increasing NaCl and PEG levels inhibited germination and seedling growth. 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. In salt, drought and seedling survival tests, Aldari showed the better performance than the others. 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.