Assessment of Iranian wheat germplasm for salinity tolerance using analysis of the membership function value of salinity tolerance (MFVS)

Salinity stress is one of the most important abiotic stresses which reduce crop production worldwide. In this study, 17 morphological and agronomic traits as indicators for identifying salinity tolerance genotypes in wheat were evaluated among a set of 110 different genotypes including advanced lines in breeding programs, and wheat landraces collected from landraces throughout Iran, some well-known tolerant and sensitive cultivars and many commercial wheat cultivars. Plant materials were grown under non-saline (NS) and saline stress (SS) conditions (Electrical conductivity [EC] of 2 and 10 ds m-1, respectively). The membership function value of salinity tolerance (MFVS) was used as a comprehensive index for the evaluation and selection of wheat salinity tolerance. The mean value of all 17 traits decreased under saline stress conditions. Among the 17 traits, spike weight (SW), kernel weight per spike (KWS), number of fertile tillers (NFT), biological yield (BY), and grain yield (GY) decreased > 25%. This suggested that these 5 traits were more sensitive to salinity stress. Ten genotypes with high salinity tolerance were selected based on MFVS and could be applied for salinity tolerance improvement in wheat. Correlation analysis indicated that the wheat salinity tolerance was significantly and positively correlated with variations of 13 traits under both non-saline and saline stress conditions (P < 0.01). Factor analysis showed that salinity-tolerant coefficients of 5 traits of grain yield, biological yield, spike weight, kernel weight per spike, and number of fertile tillers have the most interrelationships with the membership value of salinity tolerance (MFVS). Therefore, these five traits could be applied as an indicator to screen wheat germplasm for salinity tolerance in wheat breeding programs.