Effect of Combined Chilling and GA3 Treatment on Bud Abortion in Forced 'Luoyanghong' Tree Peony (Paeonia suffruticosa Andr.)

This research investigated the effect of combined chilling and GA(3) treatment on bud abortion of tree peony under greenhouse conditions to determine the dynamics of exogenous hormones and chilling effects on bud abortion. Research of such nature will increase the understanding of the effects of GA(3) and chilling level on flower development thereby, promoting off-season cultivation techniques in tree peonies to increase production that meets market demand. Hormone and sugar levels in the 'Luoyanghong' tree peony were respectively determined using High-Performance Liquid Chromatography (HPLC) and spectrophotometer. Non-potted chilling with 200 mg.L-1 GA(3) treatment reduced bud abortion rate. Flowering rate in non-potted chilling with 200 mg.L-1 GA(3) plants was 58%, as against 21% in potted chilling plants with 200 mg.L-1 GA(3) treatment. Sugar accumulation in retained or aborted flower buds was conversely related to ABA level. Low ABA and high sugar levels were noted in retained buds whereas the reverse induced bud abortion. ABA level apparently inhibited sucrose and reducing sugar uptake in aborted buds whereas GA(3) enhanced sucrose uptake in retained buds. GA(3) and IAA levels were higher in retained than in aborted buds, which made plants with retained bud more competitive in nutrient uptake (by root) for growth and development. Overall, combined chilling and GA(3) treatment enhanced plant growth and development, particularly bud sprouting, growth and flowering.