The impacts of fluctuating light on crop performance

Authors: Slattery, Rebecca; WALKER, BERKLEY - Heinrich-Heine University; WEBER, ANDREAS P M - Heinrich-Heine University; Ort, Donald

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2017
Publication Date: 2/1/2018
Citation: Slattery, R.A., Walker, B.J., Weber, A., Ort, D.R. 2018. The impacts of fluctuating light on crop performance. Plant Physiology. 176:990-1003.

Interpretive Summary: The importance of within-canopy photosynthetic performance on crop photosynthetic performance has been long recognized and there is a growing realization of the contribution from within-canopy fluctuating light on crop productivity. For example, concurrent to many studies examining the effects of sunflecks on forest understories there have been advances in examining the same illumination dynamics in major crop species such as soybean, rice and maize using both experimental and modeling approaches. Given the importance of dynamic light in crop canopies, various light-sensitive factors have been identified as targets to improve crop photosynthesis and productivity in fluctuating light conditions, including canopy and leaf morphology, C3 cycle enzyme regulation, stomatal opening/closing kinetics, photoprotection regulation, and C4 metabolite pool regulation. The mechanisms of these processes under fluctuating light conditions are the focus of this article.

Technical Abstract: Rapidly changing light conditions can reduce carbon gain and productivity in field crops because photosynthetic responses to light fluctuations are not instantaneous. Plant responses to fluctuating light occur across orders of magnitude, from entire canopies to the biochemistry of a single reaction. Although light availability and variation at the top of the canopy are largely dependent on the solar angle and degree of cloudiness, lower crop canopies rely more heavily on light in the form of sunflecks, the quantity of which depends mostly on canopy structure but may also be affected by wind. The ability of leaf photosynthesis to respond rapidly to these variations in light intensity is restricted by the relatively slow activation/deactivation of C3 cycle enzymes, opening/closing of stomata, and upregulation/downregulation of photoprotective processes. The metabolic complexity of C4 photosynthesis creates the apparently contradictory possibilities that C4 photosynthesis may be both more and less resilient than C3 to dynamic light regimes, depending on the frequency at which these light fluctuations occur, which is a focus of this study.