Photosynthetic induction of the leaves varies among pepper cultivars due to stomatal oscillation

Abstract

Photosynthetic induction describes a slow response of photosynthetic rate to transient increases in light intensity, which limits crop carbon gain and yields in nature. However, studies related to photosynthetic induction rarely focused on horticultural crops. Here, we investigate the variation in steady-state photosynthetic capacity and photosynthetic induction rate in four popular pepper cultivars in China (sweet pepper TJ-105 and chili peppers CTJ, YJJ-109 and XJ-L2). The results showed that the steady-state photosynthetic rate at a series of light intensities and CO2 concentrations was similar among the four pepper cultivars, however, the photosynthetic induction of the leaves varied widely. TJ-105 showed profound oscillations in photosynthetic rate (A) during photosynthetic induction, while others did not. The oscillations in A were mainly due to oscillations in stomatal conductance (gs), which limited A and caused an 18–25% loss of carbon gain during photosynthetic induction in TJ-105 compared to other cultivars. These results indicate that stomatal oscillations can strongly affect the accuracy of the estimation in steady-state leaf photosynthetic properties. We conclude that dynamic leaf photosynthesis gives a more reliable understanding of crop photosynthesis under the prevailing growth conditions, which is important for selecting or breeding new crop cultivars with improved light use efficiency.