Speed of light-induced stomatal movement is not correlated to initial or final stomatal conductance in rice

Abbreviations : C i – intercellular CO 2 concentration; C if – final intercellular CO 2 concentration; g s – stomatal conductance; g s,300 – stomatal conductance at 300 s of induction; g sf – final stomatal conductance; g si – initial stomatal conductance; LB – transient biochemical limitation; LS – transient stomatal limitation; P f – final photosynthetic rate; P i – initial photosynthetic rate; P N – photosynthetic rate; P 50 of g s – the time taken for g s to increase 50% of the difference between the first and final values; P 90 of g s – the time taken for g s to increase 90% of the difference between the first and final values; P 50 of P N – the time taken for P N to increase 50% of the difference between the first and final values; P 90 of P N – the time taken for P N to increase 90% of the difference between the first and final values; P 300 – photosynthetic rate at 300 s of induction; R d – dark respiration rate; W f – final intrinsic water-use efficiency. W i – initial intrinsic water-use efficiency; WUE i – intrinsic water-use efficiency; Γ * – CO 2 -compensation point in the absence of photorespiration. Acknowledgments : This work was supported by the National Natural Science Foundation of China (31671620). Conflict of interest : The authors declare that they have no conflict of interest. In nature, plants are often confronted with wide variations in light intensity, which may cause a massive carbon loss and water waste. Here, we investigated the response of photosynthetic rate and stomatal conductance to fluctuating light among ten rice genotypes and their influence on plant acclimation and intrinsic water-use efficiency (WUE i ). Significant differences were observed in photosynthetic induction and stomatal kinetics across rice genotypes. However, no significant correlation was observed between steady-state and non-steady-state gas exchange. Genotypes with a greater range of steady-state and faster response rate of the gas exchange showed stronger adaptability to fluctuating light. Higher stomatal conductance during the initial phase of induction had little effect on the photosynthetic rate but markedly decreased the plant WUE i . Clarification of the mechanism influencing the dynamic gas exchange and synchronization between photosynthesis and stomatal conductance under fluctuating light may contribute to the improvement of photosynthesis and water-use efficiency in the future.