Alkalinity and salinity tolerance during seed germination and early seedling stages of three alfalfa (Medicago sativa L.) cultivars

The germination of halophytes in saline-alkali substrates is a useful criterion for selection tolerant alfalfa (Medicago sativa L.) cultivars. The experimental conditions consisted of five levels of salinity (24, 48, 72, 96 and 120 mM) and four pH levels (7, 8, 9 and 10). The results showed that under saline conditions, the germination percentage (G(p)), plumule length (P-l) and radical length (R-l) also decreased with increasing concentration. However, under low or moderate saline conditions, P-l and fresh weight decreased sharply but R-l was the longest at 48 and 72 mM and pH 7.1, which indicated that low salinity may promote radical growth appreciably. Salinity and alkalinity stresses had synergetic effects on G(p), G(e) and G(i) but not on P-l, R-l and fresh weight. The results confirmed G(p), G(i) and G(e) are important indices for assessing germinated energy of alfalfa in salinity-alkalinity soils. Moreover, three alfalfa cultivars tested were relatively tolerant of salinity and alkalinity and Stockpile was the most tolerant cultivar in the present experiment.