In Vivo Stimulation of Axillary Bud Initiation, Growth and Development of Plantain (MUSA ABB.) using Coconut Water and Indole-3-Acetic Acid

Abstract

The study was carried out at the University of Ghana Forest and Horticultural Crops Research Centre (FOHCREC), Kade from 2008 to 2012. Two experiments were conducted to investigate the effects of coconut water (CW) alone or in combination with varying concentrations of auxin (IAA) on axillary bud initiation, growth and development of plantain (cv. Asamienu). In the first experiment, coconut water from fully matured dried fruits was supplemented with three different IAA concentrations, 10 -4 M, 10 -3 M, and 10 -2 M to produce five different coconut water : IAA ratios (v:v), viz: 8:0, 6:2, 4:4, 2:6, 0:8. Three weeks after the injection treatments, variations were seen in the rate of axillary bud formation and growth. The highest number of well-differentiated axillary buds was produced after injecting with a combination of 2ml coconut water and 6ml 10 -2 M IAA whilst the highest number of fully developed plantlets was produced with a treatment of 8ml coconut water alone. One month after the application of the bud manipulation technique, the highest number of additional well-differentiated axillary buds and fully developed plantlets was produced with 2ml coconut water plus 6ml 10 -2 M IAA and 4ml coconut water plus 4ml 10 -2 M IAA respectively. In the second experiment, the endogenous content of cytokinin (trans- zeatin riboside) and auxin (IAA) in coconut water from fruits at four different fruit maturity stages: liquid endosperm formation stage (6 months after flowering), solid endosperm formation stage (8 months after flowering), semi matured endosperm stage (10 months after flowering), fully matured dried fruit stage (13 months after flowering) and their effects on the proliferation of axillary bud initiation and development were evaluated. In both experiments, distilled water was injected as the control. Results of the quantitative analysis of the endogenous content of trans- zeatin riboside and IAA showed major changes at the different fruit maturity stages. The results indicated that as the coconut fruit matured the IAA content in the coconut water decreased while the trans- zeatin riboside content inreased with fruit maturity. Three weeks after coconut water injection treatments, the highest number of well- differentiated axillary buds was obtained for suckers treated with coconut water from fruits at liquid endosperm formation stage whilst the highest number of fully developed plantlets was produced from treatments with coconut water at semi-endosperm formation stage treatment. One month after the application of the bud manipulation technique, the highest number of additional well-differentiated axillary buds and fully developed plantlets were produced from treatments with coconut water at the liquid endosperm formation stage. Furthermore, treatments with coconut water from fruits at liquid endosperm formation stage produced the highest additional well-differentiated axillary buds one month after the application of the split corm technique whereas the highest additional fully developed plantlets was obtained from treatments with a mixture of coconut water from liquid endosperm formation stage and fully matured dried fruits. In general, treatments with coconut water from fully matured dried fruits produced the largest and the most vigorously growing plantlets.