Characterization and genetic control of germination-emergence responses of grain sorghum to salinity

Summary When grain sorghum is grown in saline soils, one cause of low yield is poor crop establishment. The objectives of this study were to assess the response of grain sorghum to salinity in the germination-emergence stages, study the inheritance of salt tolerance at this stage, and determine the relative contribution to final emergence of salt effects during imbibition, and after onset of germination. Twelve inbred lines and 18 F1 hybrids, resulting from an incomplete 6×6 factorial mating design, were tested for germination and emergence in folded paper at 10 salt concentrations, from 1.8 to 36 dSm^-1. The mean EC₅₀ (the electrical conductivity at which the variable score declines by 50%) for emerged seedlings production was 21.2 dSm^-1. Large genotypic differences were observed for salt tolerance at germination and emergence stages, which were not related to the viability of seeds, and poorly related to seed weight (considered as an estimate of intrinsic seed vigor). In the hybrids, these differences were due to SCA and female GCA for emergence, and female GCA for germination, though the male GCA was also significant for both characters. Line per se performance was significantly correlated to individual GCA estimates for emergence, but not for germination. Heterosis was only detected in three crosses for final emergence and in one cross for germination. The genetic differences in final emergence were mainly due to effects occurring after the onset of germination rather than a consequence of effects during imbibition.