Observations on cocoa flushing in Ghana under different shade regimes, with particular reference to the distribution of natural light
1990
Adomako, O. | Frimpong, E.B. | Ampofo, S.T. | Brew, K.M. (Cocoa Research Inst., New Tafo (Ghana))
Unshaded cocoa trees growing on low wet ground, as well as shaded and unshaded cocoa trees growing on dry ground were studied for the effects of sunlight availability and soil moisture on flushing. The studies covered the period of November 1982 to March 1987, which include the severe dry seasons of 1982/83 and 1983/84. Growth of cocoa seedlings and one-year old cocoa plants at the gauze house and the nursery under 35 per cent and 50 per cent shade, respectively, was also studied. In 1983 and 1986 peak flushing occurred as usual in January when there had been little or no rain during the preceding ten and four weeks, respectively. Flushing was earlier, more frequent and more intense in unshaded or 'broken canopy' and roadside (edge) trees than in shaded trees; and there was no relationship between the flushing pattern and soil moisture content. Cocoa seedlings growing under medium shade at the green house and the nursery flushed at regular (4 weekly) intervals without a seasonal peak. The one-year old jorquetted plants also flushed at regular intervals (of 4 to 5 weeks), each time at a few growing points; but as in the case of mature trees there was peak flushing involving all growing points during the drier part of the year in October-November and February-March. There was a highly significant correlation between sunshine hours and flushing (r = 0.999 and 0.949 for two different recordings in one plot). These observations are interpreted in the light of the known relationship between sunlight availability, tissue carbohydrate content, bound and free IAA levels in the plant, and flushing.
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