Physiological and growth responses of tomato plants to heat stress

Heat stress poses a significant challenge to the cultivation of tomatoes ( Solanum lycopersicum . L) as global temperatures continue to rise. This research assessed the physiological reactions of tomato plants (cv. Colibri) to elevated daytime temperatures by comparing those grown in a transparent greenhouse (heat condition, HC) with plants cultivated in a sandwich-panel greenhouse (control condition, CC). Under HC, plants showed a decrease in stem diameter, height, and fresh weight; an increase in electrolyte leakage (EL, + 25%) ; and a reduction in relative water content (RWC, − 20.3%). Additionally, heat-stressed plants exhibited changes in gas exchange, lower photosynthetic efficiency, higher malondialdehyde (MDA) levels, and an increased accumulation of various secondary metabolites, such as polyphenols, flavonoids, condensed tannins, and lycopene. These results highlight the morphological, physiological, and biochemical adjustments of tomato plants in response to higher temperatures and offer insights for selecting heat-resistant cultivars and enhancing greenhouse management strategies.