EXOGENOUS APPLICATION OF PROHEXADIONE-CALCIUM PROMOTES FRUIT COLOUR DEVELOPMENT OF 'CRIPPS PINK' APPLE

Abstract

The effects of various concentrations and number of sprays of prohexadione-calcium(ProCa) and summer pruning (SP) alone on fruit colour and other quality parameters of ‘Cripps Pink’ apple were investigated. The treatments were: (i) no spray as control, (ii) SP, (iii) 250 mg L-1 with two sprays (3 and 33 days after full bloom (DAFB), (iv) 500 mg L-1 with two sprays (3 and 33 DAFB), (v) 750 mg L-1 with two sprays (3 and 33 DAFB), (vi) 250 mg L-1 with three sprays (3, 33 and 63 DAFB),(vii) 500 mg L-1 with three sprays (3, 33 and 63 DAFB), and (viii) 750 mg L-1 with three sprays (3, 33 and 63 DAFB). Spraying was done on fruits of a whole treated tree. The reduction in shoot length was pronounced after the second spray application of ProCa regardless of concentration. The treatment of two sprays of500 mg L-1 ProCa and three sprays 500 and 750 mg L-1 of ProCa showed the highest reduction in the shoot length as compared to control. The SP alone, and three sprays of 500 and 750 mg L-1 ProCa at 3, 33 and 63 DAFB, respectively significantly improved percent red blush, percent fruit for export, higher a* value and lower b*,L* and hue angle values on the fruit as compared to control. The treatment of three sprays of 750 mg L-1 ProCa resulted the highest accumulation of cyanidin 3-ogalactosidein apple skin.