Physiological and Biochemical Responses of Pomegranate to Shading, Protective Compounds, and Potassium Silicate Under Heat and Light Stress

Due to climate change, heat stress is one of the significant problems in pomegranate-producing regions of Iran, reducing the fruit yield and quality. Therefore, it is essential to apply methods to reduce the effects of heat stress on pomegranate productivity. This study assessed the impact of shading net, kaolin, NAX-95, and potassium silicate on leaf minerals, fruit yield and quality, and some physiochemical traits of pomegranate cv. 'Malas Saveh' under intense solar radiation and high-temperature conditions. Leaves of pomegranate trees treated with shading net, kaolin, NAX-95, and potassium silicate accumulated more minerals than untreated control trees. The use of treatments, especially NAX-95, enhanced fruit diameter and length, yield, aril percentage, juice content of 100 g arils, TSS (total soluble solids), and TSS/TA (total soluble solids/titratable acidity) of fruits, and decreased fruit sunburn, skin thickness, skin percentage, and firmness of pomegranate fruits. Moreover, the use of treatments, especially NAX-95, increased the level of chlorophyll, proline, and LRWC (leaf relative water content) as well as the activity of SOD (superoxide dismutase), CAT (catalase), POX (peroxidase), and APX (ascorbate peroxidase) enzymes, but reduced the level of MDA (malondialdehyde) and H2O2 (hydrogen peroxide) in pomegranate leaves. The study findings evidenced that shading net, kaolin, NAX-95, and potassium silicate have a high potential for improving fruit yield and quality of pomegranate cultivated in regions with intense solar radiation and high temperatures.