Variation in the salt-tolerance of 13 genotypes of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] and its relationship with shoot Na+, K+, and Cl– ion concentrations

Abstract

SummaryHybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] is the type of turfgrass widely grown in tropical, sub-tropical, and warm temperate regions. Breeding salt-tolerant bermudagrass is important for turf irrigated with reclaimed or saline water, or established in saline soils. Two experiments were conducted to evaluate the variation in salt-tolerance, in shoot Na+, K+, and Cl– ion concentrations, and their inter-relationships in 13 genotypes of hybrid bermudagrass. Inter-genotypic variation in salt-tolerance was based on the relative percentages of leaf firing (3.7 – 53.7%), the relative dry weights of shoot clipping (36.3 – 70.4%), and relative root dry weights (36.4 – 356.3%). Salt stress increased shoot Na+ and Cl– ion concentrations, and decreased K+ ion concentrations in all 13 genotypes. Saline-tolerance in hybrid bermudagrass genotypes was strongly correlated with shoot K+ ion concentrations under control and saline conditions, but was not significantly, or was only weakly correlated with shoot Na+ and Cl– ion concentrations and K+:Na+ ratios. High K+ ion concentrations in shoots, resulting from the selective transport of K+ ions vs. Na+ ions from the roots, is an important mechanism for salt-tolerance in hybrid bermudagrass. Shoot K+ ion concentrations under salt stress or control conditions therefore provide a useful index for the rapid evaluation of salt-tolerance in hybrid bermudagrass genotypes.