Temperature responses of photosynthesis and respiration are critical for understanding plant growth, primary productivity of the ecosystem, and carbon balance. Plants do not live under constant temperature conditions in natural ecosystems; instead, growth temperature shows diurnal and seasonal variations. Hence, temperature responses of photosynthesis and respiration are critical for understanding the balance between photosynthesis and respiration in plants and changes in the balance between the atmosphere and terrestrial biosphere. However, the mechanisms underlying thermal acclimation of photosynthesis and respiration in plants to experimental warming are still unclear, especially in agricultural ecosystems. In this study, we examined the acclimation of foliar photosynthesis and dark respiration in maize plants by performing a field-warming experiment with infrared heaters in a typical agriculture ecosystem in the North China Plain. We also discussed thermal acclimation mechanisms and verified five hypotheses for understanding thermal acclimation mechanisms underlying photosynthesis. The results showed that experimental warming significantly increased net photosynthetic rates (An, P < 0.001) and increased the optimal temperature of An by 1.56 °C. Similarly, we found that experimental warming significantly increased the maximum rate of photosynthetic electron transport (Jmax, P < 0.001), and the optimal temperature of Jmax was increased by 1.45 °C; however, it had little effect on the maximum rate of Rubisco carboxylation (Vcmax) and its temperature sensitivity (Q10, P > 0.05). In contrast, experimental warming significantly decreased foliar dark respiration (Rd) and its temperature sensitivity (Q10, P < 0.05). Moreover, our results showed that experimental warming barely affected the ratios of Rd/Ag and Jmax/Vcmax (P > 0.05). Experimental warming significantly increased transpiration rates, but it had no effect on stomatal conductance and water use efficiency in maize leaves. These results suggest that maize plants have a limited ability to acclimate to a warmer climate in the North China Plain and that thermal acclimation may be controlled by the adjustment of photosynthesis and respiration in maize leaves. Our results may be helpful in the management of agricultural ecosystems and estimation of crop-safety risk due to global warming.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Global warming
- North China plain
- Physiological and metabolic processes