The effect of spraying with certain amino acids and plant growth regulators on the fruit set percentage and some biochemical characteristics of tissue-cultured date palm fruits (Phoenix dactylifera L.) cultivar Barhi

Abstract

     This study was conducted in a private orchard in Al-Medina district, Basrah Governorate, Iraq, during the 2022 growing season. The aim was to determine the effect of spraying date palm trees Barhi Cv. derived from tissue culture with a mixture of plant growth regulators and amino acids to improve fruit set and reduce parthenocarpic fruits. This was done using a mixture of plant growth regulators (IAA auxin, Kin cytokinin, GA₃ gibberellin) and a mixture of amino acids (glutamic Glu, glycine Gly, methionine Met, lysine Lys) at concentrations of 50 and 100 mg.L^-1, as well as their interactions and a control treatment. The study results showed that spraying with a mixture of amino acids or plant growth regulators at a concentration of 100 mg.L^-1 led to an increase in the percentage of fruit set and a decrease in the percentage of parthenocarpic fruits, reaching 57.77% and 55.55% for fruit set and 41.11% and 44.44% for parthenocarpic fruits for the two mixtures respectively. The interaction between the two mixtures was more effective, increasing the fruit set to 70% and reducing parthenocarpic fruit to 30%. Additionally, it improved the biochemical characteristics of the fruits compared to the control treatment, with the content of free amino acids (4.20 and 4.47), soluble proteins (7.12 and 7.61), total soluble carbohydrates (11.89 and 12.35), and total phenolic compounds (8.42 and 8.39) mg.g^-1, for the amino acid mixture and plant growth regulators spraying treatments respectively. The interaction between the amino acid mixture and plant growth regulators at a concentration of 100 mg/L was more effective than their individual effects.