Influence of light, temperature and water stress on germination of Hedysarum fruticosum

Hedysarum fruticosum is one of the common species for combating desertification in the semi-arid area of China, mainly because of its ability of efficient regeneration from seed and quick clonal growth. In this study, experiments were conducted to determine the effects of light intensity, constant temperature, alternating temperature and water potential (generated by PEG) on seed germination of H. fruticosum. It was found that under alternating temperature regimes, final percent germination increased from 87.2% to 99.2% when temperature increased from 5:15°C (night:day) to 10:20°C, then decreased with increasing temperature; germination could not take place at all under 25:35°C conditions in a 14h (215μmol m−2 s−1) photoperiod. Under dark conditions there was a similar final percent germination to that under light. The germination pattern under constant temperature conditions was similar to that under alternating temperature, and there were no significant differences in final percent germination and germination rate between alternating and constant temperature. Under varying light intensities, final percent germination of H. fruticosum showed no significant differences, with values always above 74.4%. When water potentials were reduced, final percent germination decreased dramatically, and few seeds could germinate at −0.2MPa. The germination rate showed a pattern similar to that of final percent germination with changing water potentials. Based on the experimental results and environmental conditions in the study area, H. fruticosum seeds should be dispersed from early to mid-May so that germination requirements can be fulfilled and higher germination is possible