Salinity effects on the early development stages of Panicum coloratum: cultivar differences

The Argentinean semiarid Chaco region is climatically suitable for cattle r aising and has an average annual rainfall of 550 mm, concentrated from Nove mber to February. There, large areas are affected by high salinity; thus, p erennial forages suitable for this region must combine adequate salt and dr ought tolerance. Panicum coloratum is a C-4 perennial grass adapted over a wide range of soil and rainfall conditions, and the purpose of this study w as to evaluate the response of two cultivars (Klein Verde and Bambatsi) to salinity. Under controlled conditions, 100 and 200 mmol l(-1) NaCl delayed germination and significantly reduced germination percentages and seedling survival in both cultivars. However, in the field, factors other than salin ity (possibly drought) had a large impact on plant survival. In short-term experiments under controlled environmental conditions, the vegetative growt h of cultivar Klein Verde was less affected by salinity than Bambatsi. The cumulative growth over one year in a saline plot was also higher in cultiva r Klein Verde. This cultivar also had higher shoot K+/Na+ ratios under sali nity, as a result of higher K+ concentrations, and accumulated more triglyc erides in roots. These features have been associated with salt tolerance in other species.