Effect of kaolin on yield, water use efficiency and physiological and biochemical responses of Page Mandarin Under moisture stress

appropriate management methods in order to increase yield and water use efficiency. For this purpose, the effect of kaolin with three levels (0, 5 and 7 percent) in three levels of moisture condition (100, 75 and 50 percent of field capacity) on page mandarin as a factorial experiment based on a completely randomized design with three replications was evaluated in 2017 at the Citrus and Subtropical Fruits Research Center of Ramsar. The results showed that under moisture stress, fruit yield, water use efficiency, chlorophyll a and total contents, the relative water content of leaves, leaf water potential, and stomatal conductance were decreased significantly. While kaolin application increased the total soluble solids, fruit yield, and water use efficiency and decreased the proline content, carbohydrates, leaf surface temperature, stomatal conductance, superoxide dismutase activity, and fruit sunburn significantly. Also, in the treatment of 50% of field capacity, 5% Kaolin application, increased fruit yield (91%), chlorophyll a (70), total chlorophyll (52%), leaf relative water content (76%), stomatal conductivity (87%) and leaf water potential (19%) compared to treatment without applying kaolin. Therefore, the kaolin application in summer and severe moisture stress conditions (50% field capacity), are recommended to create a positive effect on the reduction of production of reactive oxygen species result of oxidative stress, reduction of fruit sunburn, the increase of fruit yield and water use efficiency.