Energy partitioning under different spectral-quality light conditions in soybean.

Abstract

Light intensity and spectral quality determine photosynthesis and thus plant growth and development. Both parameters, collectively referred to as the light environment, influence the composition and structure of the photosystem II, defining energy partitioning. This partitioning is the destination of the absorbed energy to photochemical and dissipative processes and is measured by quantum yield parameters. The aim of this study was to evaluate the photosynthetic performance of two soybean genotypes under four light environments with different spectral qualities (white light, red light-enriched white light, blue light, and red light) and the same energy flux. It was observed that plants growing only in red light had lower photosynthetic efficiency and higher photodamage after prolonged exposure. This phenomenon, called "red-light syndrome"; varied depending on the soybean genotype analyzed. Furthermore, it was found that spectral deficiency during leaf development has the main effect on photosystem functional capacity. Finally, a multivariate analysis of the energy partitioning parameters provided insight into the relevance of constitutive thermal dissipation processes in the plant acclimation to different light environments.