Sex-specific physiological and growth responses to elevated temperature and CO2 concentration in Chinese seabuckthorn (Hippophae rhamnoides subsp. sinensis Rousi)

To examine whether females and males of Chinese seabuckthorn (Hippophae rhamnoides subsp. sinensis Rousi) differ in their responses to elevated atmospheric carbon dioxide (CO2) and temperature, we examined gender-specific physiological and growth responses of H. rhamnoides, exposed to elevated temperature (ET), elevated CO2 concentration (EC), and their interaction (ECT) in environmentally controlled growth chambers. We found that ET significantly decreased the high growth rate (HGR) in both sexes. There were gender differences in biomass accumulation, photosynthetic capacity, nutrient absorption, and nonstructural carbohydrate (NSCs) contents under ET condition. The growth of females was more inhibited by ET than did males. EC significantly increased HGR, net photosynthetic rate (P-n), and biomass accumulation in both sexes, especially for males. Moreover, physiological and biochemical parameters, such as root nodule biomass and N content, showed greater gender differences under ECT than under EC and ET conditions. For both females and males, ECT increased HGR, biomass accumulation, P-n, and water use efficiency (WUE). We conclude that H. rhamnoides males and females exhibited sexually differential responses to climate change.