Physiology of Photosynthesis in Plants under High-Temperature Stress

Photosynthesis is a key process for plant growth and development. However, exposure to supra-optimal temperatures disrupts the photosynthesis process through the inhibition and degradation of photosynthetic pigments, enzymes, and the photosynthetic apparatus, leading to a decrease in photosynthetic efficiency. Furthermore, supra-optimal temperatures induce premature leaf senescence, alterations in chloroplast structure, disruption of photosystems, and inhibition of electron transport. Heat stress also affects cyclic and non-cyclic electron flow and alters stomatal oscillations, which influence CO₂ influx and water balance. Photosynthetic enzymes, such as Rubisco and sedoheptulose-1,7-bisphosphatase, are highly sensitive to heat stress. Understanding the physiological responses of photosynthesis to high-temperature stress is crucial for developing strategies to enhance plant resilience and mitigate the negative impacts of heat stress on crop productivity. This chapter discusses the physiological effects of high-temperature stress on photosynthesis in plants. The impact of heat stress on various photosynthetic components, including photosynthetic pigments, photosystems, electron transport systems, and enzymes involved in carbon assimilation is discussed.