A Strategy of Additional Carbon Acquisition by Non-Foliar Photosynthesis: Implication for Yield

Photosynthesis is traditionally studied in leaves, but it extends beyond foliar tissues to non-foliar organs (e.g. stems, fruits, sepals, and seeds) offering an underexplored avenue for enhancing plant productivity. This review investigates physiological, biochemical, and developmental roles related to non-foliar photosynthesis, emphasizing its contributions to carbon assimilation and crop production under varying environmental conditions by presenting an extensive compilation of published data with relevant studies. While leaves dominate carbon fixation, non-foliar organs provide supplementary source for photo assimilates, particularly during stress or leaf senescence, yet their mechanisms and impacts remain insufficiently understood. We integrate evidence showing that stems in desert species, fruits in crops like cucumber, and reproductive structures like wheat ears contribute significantly to carbon budgets e.g., cucumber fruit photosynthesis accounts for 9.4% of total carbon accumulation, while wheat ear photosynthesis supports up to 43% of grain filling under drought. These organs employ unique pathways, such as PEPC-mediated CO₂ refixation, alongside Rubisco-driven assimilation, adapting to light, temperature, and water constraints. Our analysis reveals that non-foliar photosynthesis enhances yield potential by mitigating carbon deficits and improving resource allocation, with implications for resilience against climate stressors like heat and drought. The main objective of the review was to evaluate the non-foliar photosynthesis to additional carbon gain and their contribution compared to foliar photosynthesis. Future research should focus on quantifying these contributions across species and different cultivation conditions to emphasis their full potential.