Light-driven modulation of plant response to water deficit. A review.

The dependence of agriculture on water availability is an important premise justifying attempts to enhance water use efficiency for plant production. Photosynthetic efficiency, directly impacts biomass production, is dependent on both water availability and the quality and quantity of light. Understanding how these factors interact is crucial for improving crop yields. Many overlapping signalling pathways and functions of common bioactive molecules that shape plant responses to both water deficit and light have been identified and discussed in this review. Separate or combined action of these environmental factors include the generation of reactive oxygen species, biosynthesis of abscisic acid, stomatal functioning, chloroplast movement and alterations in the levels of photosynthetic pigments and bioactive molecules. Plant response to water deficit depends on light intensity and its characteristics, with differentiated impacts from UV, blue, and red light bands determining the strength and synergistic or antagonistic nature of interactions. Despite its significance, the combined effects of these environmental factors remain insufficiently explored. The findings highlight the potential for optimising horticultural production through controlled light conditions and regulated deficit irrigation. Future research should assess light and water manipulation strategies to enhance resource efficiency and crop nutritional value.