Comparative analysis of exogenously applied synthetic auxins and micronutrients for effective management of fruit drop and quality improvement in subtropical Japanese plum (Prunus salicina Lindl.)

Abstract

Foliar application of plant growth regulators and micronutrients is a rapid uptake strategy of plant-feeding directly through leaves irrespective of soil condition. This experiment was conducted to assess the impact of the foliar application of synthetic auxins and micronutrients on subtropical Japanese plum (Prunus salicina Lindl.) fruit yield and quality. The experiment was performed in a plum orchard based on a completely randomized block design with nine treatments and three replications. The foliar treatments included NAA 15 ppm, NAA 15 ppm + urea 2%, 2,4-D 10 ppm, 2,4-D 10 ppm + urea 2%, borax 0.50%, borax 0.50% + urea 2%, ZnSO4 0.50%, ZnSO4 0.50% + urea 2%, and control (sprayed with distilled water) applied as a two spray in 15 days interval after fruit set. Foliar application of NAA 15 ppm + urea 2% led to least fruit drop followed by highest fruit yield. The fruit physicochemical attributes including fruit length and diameter, fruit weight, pulp weight, total soluble solids, titratable acidity, sugars, and ascorbic acid were also significantly improved by foliar spray of NAA 15 ppm + urea 2%. However, all the treatments were ineffective in improving anthocyanin and total phenol content of ‘Satluj Purple’ plum. The results further revealed that reduced fruit drop followed by highest fruit yield with foliar application of NAA 15 ppm + urea 2% was associated with reduced activity of cell wall degrading enzymes viz., cellulase and polygalacturonase at abscission zone.