Physiological and ecological responses of alfalfa and milkvetch seed to PEG priming

Poor seedling emergence is one of the critical problems in grassland production in China.Osmotic polyethylene glycol (PEG 6000) priming technique (-0.6MPa, 24h) was used to study priming effects on seed germination and their physiological and ecological responses in different quality commercial seed lots of alfalfa (Medicago sativa) and milkvetch (Astragalus adsurgens). Results showed that PEG priming significantly enhanced (p<0.05) early germination and germination index, and reduced time required for 30% seedling germination, but did not influence final germination. The priming effects varied according to species, seed lot and germination conditions. Positive effects were more evident on milkvetch than alfalfa; for instance, with similar medium quality seed lots of the two species, the time during which significantly increased germination occurred was up to 6 days in milkvetch, but only 4 days in alfalfa.