Lucerne (Medicago sativa L.) selected for vigor in a nonsaline environment maintained growth under salt stress

Abstract

Lucerne populations HP32 and M69-33 (Medicago sativa L.), which were developed from Hairy Peruvian (HP) and Moapa 69 (M69) by selection for increased growth and N assimilation in nonsaline conditions, also produced more forage at 20% bloom than the original cultivars when moderate salt stress was applied after germination. During the first 45 days of seedling development, the improved populations produced as much total dry matter in the presence of 150 mM NaCl as the original cultivars did in the absence of NaCl. When plants were grown to 20% bloom with 200 mM NaCl, HP32 produced 70% more forage than HP (P=0.01), while M69-33 yielded 26% more forage than M69 (P=0.05). Because all tests were conducted in the absence of combined N, growth of the improved populations was accompanied by increased N2 fixation. Superior growth of HP32 under saline conditions was associated with greater exclusion of Na (P=0.05) and Cl (P=0.08) from the leaves. These results show that selecting for increased growth and N assimilation without salt stress in two populations of lucerne provided potential agronomic benefits in both saline and nonsaline environments.