Genotypic Variation for Salt Tolerance within and between 'Alamo' and 'Kanlow' Switchgrass (Panicum virgatum L.) Cultivars

Switchgrass tolerates nutrient and water limitations; however, high salt concentrations may inhibit its production. Therefore, the salt tolerance potential of switchgrass needs to be enhanced for economic production. The objective of this study was to determine the differences within and between two lowland cultivars of switchgrass for growth, stomatal morphology, photosynthetic pigments content, and mineral traits. A greenhouse study was conducted on 18 sublines, derived from the cultivars Alamo (A) and Kanlow (K), plus a salt-tolerant and sensitivity check (20 genotypes). A split-plot randomized complete block design was used with three replications per treatment (0, 5, 10, and 20 dS m(-1) NaCl). High salt concentrations (10 and 20 dS m(-1) NaCl) reduced shoot biomass, stem diameter, and plant height up to 21, 11, and 16%, respectively, compared to the control for all genotypes (p < 0.05). Chlorophyll a and adaxial stomata width were moderately correlated with growth traits under saline conditions (r = 0.49 to 0.56, p < 0.05). The sublines 12A-227, TN13006-04, 12A-259, 12K-247, and TN13009-08 had better growth and accumulated less salt in shoot biomass than both checks. These results indicate that differences exist within and between the Alamo and Kanlow sublines, and it is possible to breed improved cultivars with increased salt tolerance.