Geographic variations in seed germination of Dalbergia odorifera T. Chen in response to temperature

Temperature plays an essential role in regulating seed germination and seedling production. As adaptation of germination requirements can occur in response to slight differences of the local climate, studying the intra-species variations of seed germination is of great importance for its large-scale conservation, introduction and seedling production. In the present study, germination of Dalbergia odorifera from four geographic sites (namely Ledong in Hainan province, Pingxiang in Guangxi Zhuang Autonomous region, Zhaoqing in Guangdong province and Longhai in Fujian province) were investigated under five constant temperatures (15 °C, 20 °C, 25 °C, 30 °C and 35 °C). The results showed that there existed statistically significant differences (P < 0.001) among these localities, temperatures and their interactions in terms of final germination percentage (FGP) and mean time to germination (MTG). Seeds from all these localities demonstrated the lowest FGP value (27.3%, 0.0%, 8.0% and 10.0% in average) under the temperature of 15 °C, while 25 °C was the optimal germination temperature for seeds collected from Ledong and Pingxiang, and 30 °C for seeds collected from Zhaoqing and Longhai. It could be deduced that intra-specific variations in the optimal germination temperature might occur over a small scale in southern China.