Browsing by Author "Owusu Nipah, J."

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    Abscission of Control Pollinated Coconut Fruits: Preliminary Investigations into the Possible Role of Ethylene
    (2010) Owusu Nipah, J.; Safo-Kantanka, O.; Matthew J. Dickinson
    Recent advances in the spread of the Cape St Paul Wilt disease (CSPWD) necessitate a more rapid development of tolerant coconut types. Control pollination is the main method for producing legitimate coconutseeds for such breeding purposes. However, the process of bagging causes severe nut drop or abscission. Many scientists have implicated hormones as the primary regulators of organ abscission; with ethylene being particularly implicated. Unlike other plant hormones, which are mainly produced in other parts and transported to influence target organs, the production of ethylene could be initiated within the same organ, such as the fruit. This study was therefore undertaken to investigate the possible involvement -of ethylene in abscission after control pollination. Pollen from Vanuatu Tall (VTT) variety was used to cross emasculated Malayan Yellow Dwarf (MYD) inflorescence after isolation with bags. Trials were laid out in Completely Randomised and Split Plot designs, with specified replications. Two ethylene inhibitors, namely aminoethoxyvinylglycine (AVG) and silver thiosulphate (STS) were ~ed.. Five concentrations of AVG ranging from 2mg/1 to 30mg/1 were applied to inflorescences during and after bagging. AVG concentrations higher than 2 mg/1 resulted in significant reduction in abscission. Fruit yields up to five times that of ordinarily bagged treatments without AVG were recorded. Four concentrations of STS ranging between O.SmM 10mM applied in similar manner, however, did not result in any significant reduction in abscission. The results from AVG application strongly suggest the involvement of ethylene in the abscission of control pollinated coconut fruits.
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    Genetic diversity among coconut varieties for susceptibility to Cape St Paul Wilt Disease
    (2008) Baudouin, L.; Dery, S.K.; Philippe, R.; Owusu Nipah, J.; Nkansah-Poku, J.; Quaicoe, R.N.; Arthur, R.; Dare, D.; Yankey, N.; Dollet, M.
    The CSPWDis the Ghanaian formof lethal yellowing disease (LYD) of coconut, caused by a phytoplasma and has been active in Ghana since 1932. The paper updates the results of screening trials conducted with 38 pure and hybrid coconut varieties since 1981. Although no variety was found totally resistant, a wide range of susceptibility level was observed: almost all SGD were still unaffected, while the local WAT had almost totally disappeared, additive values were calculated for the parental varieties and it was shown that, in the average, hybrids are slightlymore susceptible than predicted by a purely additive model. According to this genetic model, the SGD 9 VTT hybrid will be appreciably less susceptible than the MYD 9 VTT currently being used for replanting devastated farms in Ghana. Our results tend to confirm the general trend that cultivars from the Pacific group (especially the Dwarfs) are less susceptible than the Indo-Atlantic cultivars. Proposals are made to adapt planting material to the risk level. Genetic control can only be efficient if it is considered as a link in a chain of control measures involving the choice of a proper planting site, goodmanagement and early eradication of diseased trees.