Development of a new method for breaking buds on ornamental flow
Over the past five years we have carried out a considerable amount of research on induction of bud breaking in roses, gerbera and a variety of other plants. Much of this research has focused on using Plant Growth Regulators and cultural methods (e.g. photoperiodic control in gerbera) and was funded by the Hill Foundation as well as the national IR4 program. Unfortunately of these methods, the ones that were effective did not allow targeted initiation of one particular dormant bud. Separate from that research we also carried out research to find such a targeted method. The currently-funded work is aimed at exploiting a discovery by us of such a targeted bud-breaking method. This method is based on our observation that localized axillary bud break on the flower stem of Rosa hybrida â€˜Kardinalâ€™ can be induced to break through mechanical manipulation of the stem by partially compressing the internode above a specific axillary bud. We call this treatment a â€œPartial Crushâ€ (PC) treatment. It induces a bud break at the proximal node, which will grow to produce a flower stem for subsequent harvest without harming the current stem or successive growth. The effect on cut-flower rose was to generate a specific and timed bud break from 7 to 14 days earlier than stem pruning or flower harvesting. Applying this treatment can potentially increase and better time production of cut flower roses. Furthermore, the method may be applicable in a variety of ornamental plants and it is part of this project to explore which other plants might respond to this treatment and how the treatment might need to be modified to maximize effectiveness. The scientific basis for the process of bud breaking is that apical dominance inhibits axillary bud breaks and lateral shoot branching due to the inhibitory effects of auxin (IAA), which is biosynthesized in the shoot apex and polar transported in the plant (Sachs & Thimann 1967; Leyser 2003). Axillary buds lower on a stem have a higher degree of inhibition then apical buds (Le Bris et al 1998). Apical dominance inhibits axillary bud breaks because of the polar transport of auxin through the stem from the growing apex (Kitazawa et al. 2008). Cytokinin encourages cell division and is translocated in the plant from the root upwards (Sachs and Thimann 1967). We speculated that disruption in the translocation of the growth hormones due to partial compression of the rose stem reduces auxinâ€™s inhibitory effect on the axillary bud below...
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Keywords: ICFG Hill Final Report 2008-2009