Abstract:

Research on photosynthesis parameter of summer soybean response to elevated [CO2] could help to learn about photosynthesis physiological changes of summer soybean under future Climate Change. The objective of this study was to investigate the effect of elevated (550±60 mmol/mol) [CO2] on photosynthetic pigment contents, photosynthesis of two soybean cultivars (‘Zhonghuang13’ and ‘Zhonghuang35’) with two nitrogen levels at the Free-Air Carbon dioxide Enrichment (FACE) experimental facility. The results showed that the reaction of photosynthetic pigment contents including chlorophyll a, chlorophyll b, total chlorophyll contents and carotenoid contents of soybean to high CO2 levels was difference for the two soybeans. It was not changed for ‘Zhonghuang35’ in flowering and pod period but reduced for ‘Zhonghuang13’ in pod period. The photosynthetic rates (Pn) of the two cultivars soybean were increased and the stomatal conductance was decreased with the high CO2 level. Pn increase could help soybean to better use the light, accumulate more organisms and increase the biomass and yield. The stomatal conductance decrease might reduce the soybean transpiration (Tr), which could promote the water use effect (WUE) of the soybean.