Germination responses to temperature and moisture in seed from three species of {\sl Caragana}

The germination responses to temperature and moisture in two indigenous species, Caragana licentiana and Caragana opulens, and one introduced Caragana intermedia were studied under controlled conditions in the laboratory and in the field. Germination responses to temperatures and moistures were different in the three species. The optimum temperature for seed germination is 20℃ for C. licentiana and 15℃ for C. opulens. Germination was inhibited at 5℃ for C. licentiana. Germination velocity was quick for C. opulens and even germinated 78.5% at 5℃. Average incubation period needed for seeds to germinate was longer for C. licentiana. Hard-coat seeds existed at different percentages in the species. Rate of hard-coat seeds was 4.0% for C. licentiana, and C. opulens and C. intermedia had no hard-coat seeds. Germination responses to temperature in the species were related to their ecological distribution and habitat. Germination results showed that optimum soil moisture was 10.00% in this Caragana species. The soil water content to trigger germination was 1.25% for C. licentiana and 7.50% for C. opulens.