Flowering of cacao under controlled temperature conditions

The relationship between flowering and day and night temperatures in cacao has been studied over a period of nine months in controlled environment rooms, with clonal trees which were 13 months old at the start of the experiment.

All the plants started to flower at the same time, but thereafter there was a marked response to temperature. Flowering was greater at day temperatures of 80° and 86° F. (26 .7°, 30° C.) than at day temperatures of 74° F. (23–3° C.) and, at each level of day temperature, flowering was greater at a night temperature of 80° F. than at one of 74° or 86° F. The relative effects of temperature were similar on numbers of flowering cushions per plant and of flowers per cushion.

There was no apparent relationship bfetween the amount of flowering and new leaves (flushes) produced, either at the time of flowering or at any period before. Neither was there a quantitative relationship between flowering and leaf area of the plants, though, in general, the treatments that resulted in the greatest leaf areas also resulted in the greatest numbers of flowers. A possible relationship was suggested between the number of flowering cushions and the total extension growth of the branches.