Abstract
Growth regulators can improve the quality and production of fruit trees. This research was conducted over two successive years to evaluate the effect of preharvest sprays of growth regulators on the physicochemical properties of date palm fruit (Phoenix dactylifera cv. 'Shahabi') during khalal and tamar stages in a palm research station at Bushehr province. In the first year, fruit bunches of these trees were sprayed at the kimri stage, and in the second year at the kimri and hababouk + kimri stages, using NAA (100 mg/L), GA(3) (100 mg/L), KI (100 mg/L), SA (50 mg/L), Put (1.288 × 10(3) mg/L), and distilled water as the control. Foliar spraying of 'Shahabi' date clusters with all plant growth regulators at the kimri stage did not have significant effects on traits such as length, diameter, weight and volume of the fruit compared to the control but, foliar spraying in the hababouk + kimri stage with NAA and to some extent Put caused a significant increase in these factors in the khalal and tamar stages. Foliar spraying with all growth regulators caused a significant increase in the weight of pulp in the khalal and tamar stages. With foliar application of Put, SA, GA(3), and especially NAA, cluster weight and yield percent showed a significant increase compared to the control at the tamar stage. In general, the percentage of fruit drop in the foliar application of all growth regulators in the hababouk + kimri stage was significantly higher compared to the foliar application in the kimri stage. Foliar spraying in the kimri stage significantly reduced the fruit drop compared to the control but foliar application of NAA, GA(3) and SA in the hababouk + kimri stage significantly increased the fruit drop compared to the control. Foliar spraying of all plant growth regulators in the kimri and hababouk + kimri stages caused a significant decrease in the percentage of TSS as well as the percentage of total carbohydrates compared to the control in the khalal and tamar stages. Foliar spraying with all plant growth regulators in the kimri and hababouk + kimri stages caused a significant increase in the TA percentage in khalal stage compared to the control.