The effect of foliar spraying of salicylic acid and silica on improving the quality of date fruit (Phoenix dactylifera) mazafati digit

Dates are one of the most important and strategic fruits in Iran that play a major role in providing employment and livelihood to the people and some of them are exported abroad. Improving the quality of date fruits through foliar application of plant growth regulators and various nutrients can be effective in both improving livelihoods and increasing exports. This study aimed to improve the quality of date fruit Mazafati cultivar by studying some responses of date fruit and also some physiological traits of date tree to foliar application with plant growth regulator salicylic acid and silica element.

This study was conducted in 2019, as a factorial design in a completely randomized design with three replications in a commercial date garden in Iranshahr city of Sistan and Baluchestan province. The studied date trees were Mazafati cultivar, all of which were 14 years old and were located at a distance of 7 × 7 meters from each other. Salicylic acid and silica included three levels of 0, 200 and 400 mg L-1 and 0, 100 and 200 mg L-1, respectively. After applying the treatments, fresh samples of date leaves and fruits were transferred to the Plant Physiology Laboratory of Kerman University of Graduate Studies and Advanced Technologies and some morphological and physiological traits of date tree leaves were measured. In addition, some traits related to the quality of date fruit were measured.

The results of data analysis showed that the interaction effect of salicylic acid and silica was significant for all studied traits and significantly improved the quality of date fruit. Date fruit characteristics such as cluster weight and fruit weight are affected by the interaction of 200 mg/L salicylic acid and 200 mg/L silica levels by 34 and 36%, respectively, and fruit length, kernel weight, and kernel size are affected by 200 mg/L silica. They increased by 16, 5 and 14 percent respectively. In addition, the physiological traits of photosynthetic pigments, free amino acids, reducing sugars, soluble proteins, and enzymatic antioxidants were significantly increased by the interaction of salicylic acid and silica. The interaction effect of 400 mg /L salicylic acid and 100 mg /L silica had the greatest effect on the quality of date fruit and physiological traits of date palm and can be used to improve the quality of date fruit.

Foliar application of plant growth regulator salicylic acid and silica significantly improved the quality of date fruit, part of this effect was direct and the other part was indirect through the effect on the physiological traits of tree leaves. Increasing photosynthetic pigments, free amino acids and reducing sugars in palm leaves under the influence of salicylic acid and silica, leads to more photosynthesis and increased leaf nutrients. This will lead to better nutrition of date fruits and ultimately increase their size. The results showed that the interaction effect of 400 mg L-1 salicylic acid and 100 mg L-1 silica had the greatest effect on fruit quality and physiological traits of palm leaves.