Response of seed germination of three Caragana species to temperature and soil moisture

Caragana leucophloea, C. pumila and C. acanthophylla are xeric shrubs, which have potential value in vegetation restoration. Effects of alternated temperature and soil moisture on seed germination and germination phenology of 3 species were studied. Alternating temperature regimes of 10/6, 15/6, 20/10, 25/15 and 30/20 ℃ were used while the photoperiod condition was 12 h/12 h. The results indicated that the soil moisture to trigger the germination was 2.5% for 3 species. The germination speed of C. leucophloea and C. pumila were fast and the germination could complete at the same year of the seed maturation, and could finish the emergence. But the seedling emergence was long for C. acanthophylla because of hard seeds.