ABM Sharif Hossain and Fusao Mizutani
Keywords: Dwarfing, ringing, growth inhibitor, shoot growth.
Abstract: The study was undertaken to evaluate the dwarfing effects of phloemic stress (represented by bark ringing) and growth inhibitors [abscisic acid hormone (ABA), Maleic hydrazide (MH) and cycocel (CCC)] applied to a connecting bark strip of partially ringed trunk by using two-year-old peach trees. A 2 cm length of bark was removed from the trunk leaving a 2 mm width connecting bark band to which the aqueous chemical solutions (ABA, MH and CCC) were applied. Positive correlations were found between the bark regeneration and tree growth. Higher concentrations of ABA, MH and CCC retarded both bark regeneration and shoot growth. ABA and MH showed the greater effect than CCC. ABA 2000 showed the greater effects than ABA 1000 ppm which completely inhibited the bark regeneration even resulting in tree death like complete ringing. Root weight was also reduced in accordance with the decline in bark regeneration. Thus these results indicate that the tree growth can be controlled by chemically modifying bark regeneration of partially ringed trees in which a 2 mm connecting strip (97% ringing) was left. The use of chemicals will be greatly reduced compared with the whole tree spray for tree dwarfing.
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