Exogenous Calcium Enhances Osmotic Regulation, Photosynthetic Machinery and Stomatal Characteristics in Banana Under Dehydration Stress

Agriculture faces significant challenges due to a rapidly growing global population and the effects of climate change, leading to various forms of stress like drought, heat, salinity, and extreme weather. These stressors are unpredictable and complex, making them particularly harmful to crop productivity. Drought stress disrupts plant water balance, affects physiological functions, and lowers yields, posing a significant threat to banana cultivation. About 45% of agricultural land faces water deficiency, causing nearly 50% global production losses, with water shortages expected to worsen. Strategies are needed to improve plant resilience. Calcium (Ca²⁺) serves as a key secondary messenger in plant signalling pathways, influencing various cellular processes. However, its effect on stomatal development, under drought stress conditions, remains relatively understudied. This study investigated exogenous calcium’s impact on the osmotic regulation, photosynthetic machinery and stomatal index in banana plants under drought stress. Our findings indicated that drought stress led to a reduction in morphological growth attributes and photosynthetic pigments in banana plants. However, the exogenous foliar application of calcium significantly enhanced growth characteristics and improved photosynthetic performance (Chl a by 43.70%, Chl b by 45%, total chlorophyll by 40.6% and carotenoid by 44.1%) under drought stress. Additionally, calcium stimulated the accumulation of total soluble sugars and proline content by 33.3% and 27.27%, respectively which were positively associated with improved leaf water status in drought-stressed plants. These findings provided promising insights into the potential of exogenous Ca²⁺ to enhance stress resistance tolerance in banana plants, thereby offering a pathway to improve crop productivity and facilitate adaptation to climate change challenges.