Salt Tolerance of Six Switchgrass Cultivars

Panicum virgatum L. (switchgrass) cultivars (Alamo', Cimarron', Kanlow', NL 94C2-3', NSL 2009-1', and NSL 2009-2') were evaluated for salt tolerance in two separate greenhouse experiments. In experiment (Expt.) 1, switchgrass seedlings were irrigated with a nutrient solution at an electrical conductivity (EC) of 1.2 dS.m(-1) (control) or a saline solution (spiked with salts) at an EC of 5.0 dS.m(-1) (EC 5) or 10.0 dSm(-1) (EC 10) for four weeks, once a week. Treatment EC 10 reduced the tiller number by 32% to 37% for all switchgrass cultivars except Kanlow'. All switchgrass cultivars under EC 10 had a significant reduction of 50% to 63% in dry weight. In Expt. 2, switchgrass was seeded in substrates moistened with either a nutrient solution of EC 1.2 dS.m(-1) (control) or a saline solution of EC of 5.0, 10.0, or 20.0 dS.m(-1) (EC 5, EC 10, or EC 20). Treatment EC 5 did not affect the seedling emergence, regardless of cultivar. Compared to the control, EC 10 reduced the seedling emergence of switchgrass Alamo', Cimarron', and NL 94C2-3' by 44%, 33%, and 82%, respectively. All switchgrass cultivars under EC 10 had a 46% to 88% reduction in the seedling emergence index except NSL 2009-2'. No switchgrass seedlings emerged under EC 20. In summary, high salinity negatively affected switchgrass seedling emergence and growth. Dendrogram and cluster of six switchgrass cultivars indicated that Alamo' was the most tolerant cultivar, while NSL 2009-2' was the least tolerant cultivar at both seedling emergence and growth stages. A growth-stage dependent response to salinity was observed for the remaining switchgrass cultivars. NSL 2009-1' and NL 94C2-3' were more tolerant to salinity than Cimarron' and Kanlow' at the seedling emergence stage; however, Kanlow' and Cimarron' were more tolerant to salinity than NSL 2009-1' and NL 94C2-3' at the seedling growth stage.