干旱区生态环境知识资源中心

Artemisia sphaerocephala is widely used for vegetation rehabilitation, but its germination is very low after air seeding of achenes. We explored effects of light, temperature and water stress on germination. Results show that both final percent germination and germination rate were increased by temperature increment, with the highest values occurring at 15 : 25° C (night : day) in dark and 20 : 30° C under light. Light inhibited germination, especially at lower alternating temperatures (5 :15° C and 10: 20° C). The alternating temperature window for germination was slightly narrower under light than in dark, and germination was slower under light than in dark across the temperature range. Achenes incubated in the dark and at constant temperatures had over 80 % germination at 10 to 25° C, with an optimum at 20° C. Under dark and 25 μ mol m(-1) s(-1) light flux density at 10 : 20° C, final percent germination was over 94 %, but if the light flux density was increased to 100 and 400 μ mol m(-2) s(-1), final percent germination was significantly lower (64 % and 38 % respectively). However, achenes could keep their germination capacity for a long time (over 50 days) and germinate well after going back to the dark. Germination was also lower under water stress and few achenes germinated at -1.4 MPa. This was more pronounced at high and low temperatures. Given these findings and the prevailing climatic characteristics, the most suitable time for air seeding of achenes may be mid-May.