Persistence after Three Cycles of Selection in NewHy RS‐Wheatgrass (Elymus hoffmannii K.B. Jensen & Asay) at Increased Salinity Levels

Abstract

Difficulties associated with producing high quality forage on salt affected soils is often associated with the inability of plants to establish and persist at elevated soil salinity levels. The cultivar NewHy RS‐wheatgrass is recommended for use on range sites with moderate salinity problems that receive at least 35 cm of annual precipitation. Objectives of this study were to evaluate (i) the ability to improve plant persistence in NewHy over three cycles of greenhouse selection at increased salinity levels and (ii) corresponding changes in seedling vigor and germination under nonsaline conditions. Greenhouse grown plants were irrigated every 3 d with a complete nutrient solution and salt levels were increased by an electrical conductivity (EC) of 6 dS m−1 every 1 to 2 wk until an EC level of 42 dS m−1 was reached and maintained until plant mortality occurred in 2002 and 2003. Probit analysis was used to estimate the time and salt concentration required to kill 50% of the plants (LD50) in each cycle. Significant differences for LD50 were found among the different cycles of NewHy selected for persistence under saline conditions and the quackgrass [Elytrigia repens (L.) Nevski] parent with a resulting ranking of Cycle‐3 > Cycle‐2 > Cycle‐1 > quackgrass > NewHy (Cycle‐0). The largest single gain was achieved from NewHy Cycle‐0 to Cycle‐1, which required an additional 145 ECdays to reach an LD50 level. Smaller increases were observed between Cycles‐1 and ‐2 and between Cycles‐2 and ‐3. Selection for persistence under a saline environment did not reduce seedling germination rate or vigor.