Preharvest foliar spray of plant growth regulators expand the harvest season and improve fruit quality of acid lime (Citrus aurantifolia (Christm) Swingle)

Abstract

Purpose: Lime (Citrus aurantifolia) is a lucrative crop with a year-round demand. However, seasonality in fruiting causes market glut. Therefore, potential of gibberellic acid (GAs), brassinolide (BL) and salicylic acid (SA) as preharvest foliar sprays on widening narrow harvest window alongside improved fruit quality were studied. Research Method: Experiments were performed on five-year-old 30 lime trees of cv. Monaragala Local. Trees were treated with aqueous solutions of GA (12.5, 25.0, 37.5 mg L-1), BL (0.5, 1.0, 1.5 mg L-1) and SA (1, 2 and 3 mmol L-1) at 4-5 mm and 12-15 mm diameter stages of fruit growth. Findings: Two higher doses of GA (25.0 and 37.5 mg L-1) delayed lime fruit maturity by ≈25 - 40 days while the highest dose of BL (1.5 mg L-1) and the lowest dose of SA (1.0 mmol L-1) advanced fruit maturity by ≈75-80 days significantly (p<0.05). Treatment with PGRs resulted in improved fruit weight, size, shape, firmness, and peel colour compared to the control. Research limitations: High cost of plant growth regulators specially BL hampered its commercial applicability. Originality/Value: preharvest foliar application of 37.5 mg L-1 GA which delayed the fruit maturity by ≈40 days and 1.0 mmol L-1 SA which hastened the maturity by ≈80 days could be recommended to expand the existing acute harvest window along with improved fruit quality

Keywords

• brassinolide
• fruit maturity
• gibberellic acid
• growing degree days
• salicylic acid