Rainfall and temperature effects on flowering and pollen productions in cocoa

Abstract

Production of non-functional pollen by plant reduces effectiveness of pollination. A study was carried out at Cocoa Research Institute of Nigeria, Ibadan to determine the influence of rainfall and temperature on flowering intensity of selected clones of Upper Amazon cocoa (Theobroma cacao), as well as its pollen fertility. Eight clones of T. cacao used were T17/11, T7/12, T12/5, T86/45, C23, C64, C77 and Pa 24. The number of flowers at varying locations was recorded. The anthers were squashed in acetocarmine, and examined under the microscope to determine pollen fertility of each clone. The result showed that flowering intensity was regulated by rainfall and temperature and varied among the eight clones studied. The number of flowers produced by the various clones ranged from 128 for clone C23, to 415 for clone T86/45 in both January and May. The number of flowers produced on the ventral surface (V) of the clones was significantly higher (p < 0.05) than that from the dorsal region. More pods per cushion would be produced if more of the flowers produced at the dorsal (lower or abaxial) region were pollinated by pollinators in the seed garden. Clone T86/45 had the highest pollen viability
(92.11%), while clone T12/5 recorded the lowest pollen viability ( 81.06%).

Key Words: Cocoa flowering, Theobroma cacao, Upper Amazon