Abstract
Plants are often confronted with light fluctuations from seconds to minutes due to altering sun angles, mutual shading, and clouds under natural conditions, which causes a massive carbon loss and water waste. The effect of stomatal morphology on the response of leaf gas exchange to fluctuating light remains disputable. In this study, we investigated the differences in leaf stomatal morphology and photosynthetic induction across twelve rice genotypes after a stepwise increase in light intensity. A negative correlation was observed between stomatal size and density across rice genotypes. Smaller and denser stomata contributed to a faster stomatal response under fluctuating light. Plants with faster stomatal opening also showed faster photosynthetic induction and higher biomass accumulation but lower intrinsic water use efficiency (iWUE) under fluctuating light. Moreover, stomatal morphology seemed to have less effect on the initial and final stomatal conductance, and there was a minimal correlation between steady-state and non-steady-state stomatal conductance among different rice genotypes. These results highlight the important role of stomatal morphology in regulating photosynthetic efficiency and plant growth under fluctuating light conditions. To simultaneously enhance leaf iWUE when improving the photosynthetic efficiency under fluctuating light, it may be necessary to take biochemical processes into account in the future.
Highlights
Speaking, the photosynthetic induction is mainly limited by stomatal kinetics, and only the biochemical process has a very short-term limiting effect due to the rapid activation rate of electron transport and Rubisco (Yamori et al, 2016; Deans et al, 2019; De Souza et al, 2020)
Some studies have reported that stomatal movement in response to environmental fluctuations is often affected by stomatal morphology (Lawson et al, 2014; Fanourakis et al, 2020); other studies have suggested that there is no correlation between stomatal kinetics and stomatal morphology (Eyland et al, 2021)
It is worth noting that P50g has a stronger correlation with the stomatal morphology than P90g, suggesting that the initial phase of stomatal response might be more likely affected by stomatal morphology (Figures 7A–D)
Summary
It is urgent to increase crop productivity to meet the demands of the growing population (Ashraf and Akram, 2009). Photosynthesis is widely accepted as a vital target to improve crop productivity due to its importance in supporting plant growth (Long et al, 2006; Lawson et al, 2012; Wu et al, 2019), the direct relationship between leaf photosynthesis and the level of whole plant growth is still controversial. Photosynthetic Induction in Rice photosynthetic response to fluctuating light (Qu et al, 2016). On the shift to illumination from a shading environment, the photosynthetic rate tends to exhibit a typical delay response before reaching a new steady-state, which takes tens of minutes and is called photosynthetic induction (Taylor and Long, 2017; Adachi et al, 2019). Speaking, the photosynthetic induction is mainly limited by stomatal kinetics, and only the biochemical process has a very short-term limiting effect due to the rapid activation rate of electron transport and Rubisco (Yamori et al, 2016; Deans et al, 2019; De Souza et al, 2020)
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