ISHS Acta Horticulturae 49: III Africa Symposium on Horticultural Crops
REGULATED RIPENING OF COFFEA ARABICA L. IN KENYA: STUDIES ON THE USE OF 2-CHLOROETHYL PHOSPHONIC ACID |
| Authors: | W.R. Opile, G. Browning |
| Abstract:
Sprayed once at 1 400 ppm CEPA failed to concentrate the harvesting of trees bearing crop from multiple flowerings, although ripening was still brought forward. At a low altitude site, where fruits develop more quickly, CEPA at 1 400 ppm, applied to 28-week-old fruits from a single, large flowering, spread the harvesting period over 8 compared to 5 weeks required to harvest the unsprayed trees. In this experiment the proportion of fruits starting to ripen depended on the concentration of CEPA used. At a medium altitude site (1632 m) fruits sprayed with CEPA at 1 400 ppm 12, 10, or 8 weeks before natural ripening had approximately 30% fewer grade A beans, but bean size in fruits sprayed later than this was not affected. Early ripening did not reduce the liquoring quality of the beans in any of the experiments conducted. Fourty per cent of flower buds sprayed with CEPA at 1 400 ppm 5 days before dormancy release abscissed when they expanded, but the remaining flowers set fruit normally. Sprays at 1 400 ppm CEPA significantly reduced internode lengths without affecting node production. Sprayed at concentrations from 1–200 ppm in December, when the main crop was ripening, naphtaleneacetic acid reduced the additional leaf abscission induced by CEPA sprayed at 1 400 ppm by 15–20%. After spraying with triiodobenzoic acid (TIBA) at 10 ppm 35% of the ripe cherries on trees could be shaken off compared with 28% for trees sprayed with CEPA at 1 400 ppm. The number of cherries falling was increased to 50% when both CEPA at 1 400 ppm and TIBA at 50 ppm were sprayed, and many of the fallen fruits had fully developed abscission layers. | |
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