Combining ability of salinity tolerance on the basis of NaCl-induced K+ flux from roots of barley

Salinity is a major abiotic stress affecting agricultural production. To understand the genetic behavior of salinity tolerance traits, a half-diallel cross was made among six barley cultivars (Hordeum vulgare L.), with contrasting levels of known tolerance, to study the combining ability of salinity tolerance on the basis of K+ loss from plant roots under saline conditions. The glasshouse pot experiments showed that the six parents were significantly different in salinity tolerance and those tolerances were highly correlated with the K+ flux measurements. The combining ability analysis showed that the variances of both general combining ability (GCA) and specific combining ability (SCA) were highly significant. Two tolerant cultivars, CM72 and Numar, showed significantly higher GCA for salinity tolerance (less K+ loss under salinity stress). Cultivars with medium GCA were YU6472 and Yan90260. Salinity tolerance was mainly controlled by additive effects with the tolerance allele showing partial dominance. High positive SCA was also found between two tolerant cultivars and between tolerant and medium-tolerant cultivars, indicating possible different tolerant genes or some minor genes in these cultivars: The combination of these genes from different sources of tolerant cultivars should produce cultivars with even greater tolerance.