ISHS Acta Horticulturae 645: VII International Mango Symposium
CHANGES IN PHOTOSYNTHESIS, IAA EXPORT FROM LEAVES AND CYTOKININS IN THE XYLEM SAP AFTER GIRDLING OF YOUNG MANGO TREES IN COMBINATION WITH DIFFERENT GROWTH REGULATORS AND THEIR POSSIBLE SIGNIFICANCE FOR FLOWER INDUCTION |
| Authors: | M. Hegele, N. Boonplod, F. Bangerth, D. Naphrom, A. Chattrakul, P. Sruamsiri, P. Manochai |
| Keywords: | Mangifera indica L., plant hormones, auxin transport inhibitors, morphactin, npa, transpiration, stomata conductance |
| Abstract:
Even though several experiments have confirmed the promotional effect of girdling, application of morphactin or a combination of both on flower induction in mango trees, little is known about the physiological and hormonal changes induced by these treatments, which might be responsible for the transition from vegetative to generative bud development. Therefore, we mechanically girdled young, potted mango trees. Part of the girdled trees were additionally “chemically girdled” with two auxin transport inhibitors, viz. morphactin and naphthyl-phthalamic acid. Although none of the treatments induced flowering in the young trees, all treatments reduced photosynthesis, transpiration and stomata conductance for at least 14 days. Furthermore, a considerable increase in leaf polar IAA export could be measured, which, because of the restriction imposed by the mechanical / chemical girdle, could not reach the roots of the trees. Possibly as a result of this, cytokinins (CKs) in the xylem sap of the treated trees increased significantly. A hypothesis is presented trying to explain how IAA export from leaves and CKs from roots could induce mango trees to flower even under non-inductive temperatures. | |
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