Abstract:Controlled experiments were conducted to investigate the effect of light and temperature on seed germination of Pugionium cornutum (L.) Gaertn. and its congeners P. dolabratum Maxim., to better understanding how they adapt to desert habitats at seed germination stage. Results showed that light significantly (P<0.05) inhibited seed germination, and the inhibition effects was stronger on P. cornutum than P. dolabratum. At constant incubating temperature and darkness, the seed of both species can germinate at gradients from 15℃ to 35℃, and the germination percentages of P. cornutum were significantly higher than those of P. dolabratum at 15℃ and 35℃ respectively. The optimal germination temperature for P. cornutum and P. dolabratum were at 25℃ and 30℃ respectively. Under alternating temperature and darkness conditions, the optimal temperature for seed germination of two congeners was both occurring at 20/30℃(12h/12h). Percentages of seed germination were higher at 20/30℃ than their respective optimal constant temperatures of both species; In addition, seedling hypocotyl and radicel length of both species developed at 20/30℃ were shorter than that at 25℃ and 30℃ respectively, but their dry weight were not obviously declined. Indicating alternating temperature has advantages for seed germination and seedling development of two congeners. In summary, darkness and at 20/30℃ daily alternating temperatures are the favorable conditions for seed germination and seedling establishment of these two desert species.