Foliar application of natural reflective minerals enhances physiological performance and yield of Vitis vinifera L. cv. Chardonnay under Mediterranean climate stress

Mediterranean viticulture faces increasing challenges from severe thermal and water stress induced by climate change, which threaten both yield and grape quality. This study eval­uated the effectiveness of foliar applications of three natu­ral reflective mineral products, zeolite (TZL), basalt powder (TPB), and kaolin (TK), as sustainable adaptation strategies for Vitis vinifera L. ‘Chardonnay’ cultivated under typical Mediterranean conditions. The experimental trials demonstrated that these mineral-based reflective films are effective agro­nomic tools for mitigating heat and drought stress. All treat­ments significantly increased yield and average bunch weight compared with the untreated control, reducing losses caused by berry dehydration. Among the tested materials, zeolite (TZL) achieved the highest bunch weight and superior phys­iological performance. Ecophysiological assessments con­firmed that reflective treatments preserved photosynthetic function by reducing photoinhibition and improving both net photosynthesis (Pn) and water-use efficiency (WUE). While zeolite provided the best overall physiological and productive response, basalt powder produced grapes of the highest quality. Overall, the use of natural reflective miner­als—particularly zeolite—emerges as an innovative and envi­ronmentally sustainable approach to optimizing vine energy and water balance, thereby maintaining high-quality grape production in Mediterranean regions increasingly affected by global warming.