Effects of Gibberellic Acid, Brassin, and Auxin on Fruit Quality of ‘Pinkerton’ Avocado

Abstract

Study on the effect of plant growth regulators on fruit quality of the ‘Pinkerton’ avocado, was conducted at Thung Roeng Royal Project Development Center, Hang Dong district, Chiang Mai province. The experimental design was a completely randomized design (CRD) with 3 replications and 7 treatments; 1 ) control (tap water), 2) 25 mg / L gibberellic acid (GA₃), 3) 50 mg / L GA₃, 4) 0.5 mg / L brassin (BR), 5) 1.0 mg / L BR, 6) 15 mg / L Maxim^® (3, 5, 6 - TPA) and 7) 30 mg / L Maxim^®. All treatments were sprayed on fruit for 2 times, the first time was at 1 month after fruit setting at 50 mm of fruit width and 80 mm of fruit length and the second time was at 1 month before harvesting. Results showed that spraying 25 mg / L GA₃ resulted in more fruit width increasing in September (23.99 %) than control (19.67 %) significantly. Whereas, increasing in fruit length of all treatments were not different. Spraying 0.5 mg / L BR and 15 mg / L Maxim^® resulted in higher fruit weight at harvesting time than the control fruit significantly. Moreover, both concentrations of Maxim^® gave high skin thickness. Spraying 0.5 mg / L BR and GA₃ 50 mg / L increased total fatty acid as compared to control. Furthermore, spraying 15 mg / L Maxim^® gave the highest percentage of palmitoleic acid and linoleic acid. All spraying treatments of PGRs, especially 50 mg / L GA₃, showed the increasing in oleic acid (unsaturated fat) significantly as compared to all treatments.