EFFECT OF CPPU AND GA₃ ON GROWTH AND QUALITY OF 'MARROO SEEDLESS' GRAPE

Concentration effects of forchlorfenuron (CPPU), N-(2-chloro-4-pyridnyl)-N’-phenylurea and gibberellic acid (GA₃) on cluster weight, berry number and juice characteristics of ‘Marroo Seedless’ grape were studied at Pakchong Research Station, Pak Chong, Nakhon Ratchasima, Thailand from 28 February to 10 June 2012. Inflorescences were sprayed with 20 ppm CPPU at seven days after full bloom, resulting in a highly significant difference in cluster weight (436.80 g) and berry number (263.13 berries per cluster). Without the application of plant bioregulators, the heaviest berry weight and berry size were 2.68 and 1.58 cm in diameter, respectively. Clusters sprayed with 100 ppm GA₃ at seven days after full bloom and inflorescences sprayed with 2.5 ppm GA₃ at seven days before bloom produced excellent quality grape juice.