Mitigation of fruit splitting in Daisy mandarin through modulation of peel enzymatic activity and biochemical traits by growth regulators

Fruit splitting is a significant pre-harvest physiological disorder, results in considerable yield losses and reduced fruit quality in Daisy mandarin, thereby limiting its commercial viability. The present investigation was conducted during 2021 and 2022 to evaluate the efficacy of plant growth regulators (PGRs) in mitigating fruit splitting in Daisy mandarin budded on rootstocks Rough lemon and Carrizo citrange. Different PGRs were applied as a foliar sprays at critical stages of fruit development. From the pooled analysis, it was concluded that foliar application of SA at 100 ppm was most effective in reducing fruit splitting by enhancing the peel integrity and biochemical attributes. SA application significantly reduced the activities of cell wall degrading enzymes, including polygalacturonase (PG), cellulase, peroxidase and β-galactosidase, thereby maintaining the cell wall strength. Additionally, it reduced the concentrations of total soluble sugars, proteins and amino acids in the peel, which contributed to improved structural stability. Furthermore, SA treatment enhanced peel thickness, chlorophyll content, proline accumulation and antioxidant activity, collectively improving peel firmness and resistance to splitting. Although, extensive research has been conducted in citrus fruit physiology, limited information is available on the biochemical and physiological pathways influenced by PGRs in Daisy mandarin. This study provides a novel insights into the role of SA in regulating peel characteristics and maintaining fruit integrity. The findings suggest that foliar application of SA at 100 ppm can be effective strategy for managing fruit splitting and improving fruit quality, thereby enhancing the commercial production of Daisy mandarin.