Abstract
To develop practical flowering-acceleration techniques for summer-to-autumn flowering small-flowered spray type chrysanthemums harvested in August, the effects of gibberellic acid (GA) application after the flower budding stage on the flowering and cut flower quality were investigated. In experiment 1, GA application (50 or 100 ppm, 2 or 3 times) for ‘Sansui’ was started at the terminal flower budding stage. In almost all GA applications, flowering of the second lateral flower accelerated, and the flower cluster and pedicel lengths increased. In experiment 2, GA application (100 or 200 ppm) for ‘Sansui’ and ‘Kurenai’ was started at the flower budding, 10 days after budding, and bud break stages. Flowering accelerated in almost all GA applications. Flower cluster and pedicel lengths increased with GA application at the flower budding and 10 days after budding stages but were not affected at the bud break stage. In experiment 3, GA application (100 or 200 ppm) was started when the terminal flower bud diameter was 3.5 (flower budding), 6, and 8.5 (bud break) mm, respectively. Flowering accelerated in all GA applications. Flower cluster and pedicel lengths increased in GA application at 3.5 and 6 mm diameters, but were not affected at 8.5 mm. Therefore, GA application (100–200 ppm, twice) after the bud break stage accelerates flowering without reducing the cut flower quality.
