Kaolin Improves Photosynthetic Pigments, and Antioxidant Content, and Decreases Sunburn of Mangoes: Field Study

The Keitt mango tree has a low canopy that leads to an increase in sunburned fruits. Hence, the fruit quality is markedly reduced due to the fruit being exposed to physiological disorders. The sunburn injury problem is common due to high levels of solar radiation and the low number of leaves, which minimizes the protection of small, newly formed fruits. Kaolin spray has emerged as a promising approach for mango trees since it improves vegetative growth, yield, and fruit quality in new lands. This search aimed to study the influence of spraying kaolin on Keitt mango trees grafted on ‘Succary’ rootstock. The treatments were as follows: control, 2%, 4%, and 6% of kaolin. Our results indicated that the applications of kaolin significantly improved leaf area, tree canopy volume, photosynthesis pigments such as chlorophyll-a and b, carotenoids of leaf and yield (kg/tree), and the physical and chemical characteristics of Keitt mango cultivar in comparison with the control. A higher concentration of kaolin decreased the leaf content of antioxidants such as total phenolic, total flavonoid, CAT, POX, and PPO enzyme activities. Furthermore, the number of sunburned fruits was significantly reduced after the application of kaolin in comparison to control fruits. Regarding vegetative growth, our results indicated that adding kaolin at 6% enhanced the leaf surface area and tree canopy volume compared to the control and other treatments. A similar trend was noticed regarding yield and fruit quality, whereas the best values were obtained when kaolin was sprayed at a concentration of 6%. In conclusion, the application of kaolin can improve the production and fruit quality of Keitt mango trees by reducing the effects of adverse summer conditions.