Effect of some Growth Regulators on Productivity, Fruit Quality and Storability of Sugar Apple Anona squamosa, L.

Abstract

Many developmental processes in plants require growth regulators such as CPPU, NAA, and brassinosteroids (BRs). In this study, ten-year-old sugar apple trees were subjected to eight treatments: control (Only Water), hand pollination, CPPU at 4 mg/L, CPPU at 6 mg/L, BRs at 1.5 mg/L, BRs at 2 mg/L, NAA at 50 mg/L, NAA at 75 mg/L. Hand pollination was installed at the same time as the trees were sprayed with plant growth regulator during the 2019 and 2020 seasons, respectively, at the anthesis stage or functionally pistillate flowers on stage (pre female to female), and was repeated once weekly for five weeks after anthesis. At harvest, a random sample of fruits from each replication was taken and stored for 12 days at 12^o C in air (90-95 percent relative humidity) and measured during cold storage periods in fiberboard boxes with vented plastic liners (every 4 days in both seasons). Results indicated that significantly highest fruit set, fruit retention, number of fruits and yield was observed in the treatment BRs at 2 mg/L, while, the highest fruit drop percentage recorded with control, and the lowest fruit drop percentage recorded with NAA at 75 mg/L, as compared with other treatments. Furthermore, at harvest, physical properties, data induced significantly higher values of fruit length, diameter, weight, pulp weight and number of seeds per fruit with foliar application of 2 mg/L BRs followed by 1.5 mg/L BRs, while, hand pollination significantly increased peel weight, followed by NAA at 75 mg/L and control treatment, as compared to the other treatments during both seasons.

Concerning cold storage period, In both seasons, spraying BRs at (1.5 and 2) mg/L resulted in the highest values of TSS, total sugars, vitamin C, and the lowest values of acidity when compared to other treatments. Fruit weight loss, physiological and pathological disorders were reduced in both seasons with high concentrations of BRs, CPPU and NAA.