Identification of salinity tolerance in sorghum germplasm in National Plant Gene Bank of Iran

In order to screen sorghum germplasm in National Plant Gene Bank of Iran for salinity tolerance, 142 sorghum accessions from five different types were planted in two different field growing conditions. Electronic conductivity (EC) of irrigation water was 2.12 and 14.8 ds/m in non-stress and salinity stress conditions, respectively. Experimental design was Balanced Group Blocks with two replications. The grouping in each block was based on sorghum types (wild, grass, grain, forage, and broom sorghums). This experimental design allowed us to compare sorghum types in order to differentiate and identify the most tolerant and susceptible germplasm. Stress susceptibility index (SSI) and stress tolerant index (STI) based on single plant biological yield and plant height traits were used in the analysis. Based on these indices the tolerant accessions were identified within and between sorghum types. The distribution of tolerant and susceptible accessions in each type was determined by using biplot for SSI and STI. These analyses facilitated the identification of the tolerant germplasm in both local or introduced accessions. These germplasm can be used in sorghum breeding programs for tolerance to salinity. Passport data showed that there was no correlation between the tolerance to salinity and the origin of germplasm. However, the correlation coefficients of STI, SSI, yield and plant height showed a high relationship between STI and the first cutting yield (r = 0.695**), implying that STI is the most suitable index for screening sorghum germplasm for tolerance to salinity stress.