Sap dynamics and its management in commercial mango cultivars of Pakistan.

摘要

Different experiments have been conducted to devise a strategy for sapburn management in commercial mango cultivars of Pakistan. In the first experiment, the effect of harvest time of a day and total sap quantity in 2 mango cultivars was studied. Sindhri was harvested at 09.30, 11.30, 15.30 and 18.30 h, whereas Chaunsa at 07.00, 11.00 and 15.00 h. Sap collected from Chaunsa was 11.89 times higher than that from Sindhri and the quantity of sap exuded early in the morning was greater than later during the day. In the second experiment, 36 fruits per cultivar (Anwar Ratoul, Chaunsa, Sindhri and Dusehri) were harvested at the same time in the morning. Nine fruits were de-stemmed immediately after harvest and their sap quantity was measured. Similar procedure was repeated after one, 2 and 4 h of harvest. There was a little effect of delayed de-stemming on sap quantity. The total sap quantity was maximum in Chaunsa (spurt, 0.77 ml and ooze, 0.54 ml) and minimum in Sindhri (spurt, 0.15 ml and ooze, 0.08 ml). In the third experiment, 3 commercial mango cultivars were tested against spurt and ooze sap to observe the sapburn susceptibility after 24, 48 and 72 h, at 2 different storage conditions (ambient: 25+or-1 degrees C; cold storage: 14 degrees C, at 85 relative humidity, RH). Chaunsa was the most susceptible, followed by Sindhri and Dusehri. Sapburn incidence in Chaunsa was higher at 25+or-1 degrees C than at 14 degrees C. In Sindhri and Dusehri, sapburn incidence was almost similar at both temperatures. In the fourth experiment, the level of sapburn severity in Chaunsa was studied with reference to harvest time of a day (08.00, 11.00 and 15.00 h). Sapburn severity increased as daytime proceeded. After 7 days of storage at ambient temperature (25+or-1 degrees C) as well as in cold storage (13+or-1 degrees C, 80-85 RH), the average sapburn severity score was maximum (1.08) in fruits harvested at 15.00 h, while minimum (0.06) in fruits harvested at 08.00 h. In another experiment, fruits were placed on de-sapping trays for different periods to determine the optimum time of de-sapping to reduce the incidence of sapburn injury. After 15 days of storage at 13+or-1 degrees C and 80-85 RH, the minimum sapburn injury (0.65) occurred in fruits placed for 20 minutes on a de-sapping tray, followed by 10 minutes (0.73), compared with the control (2.54) or fruits harvested by traditional method. The results will be used to determine a practical sapburn management approach in commercial mango cultivars of Pakistan.