Phenology of flowering in cacao (Theobroma cacao) and its related species in Nigeria

Abstract

Adequate utilization of genetic variability in both cultivated and wild relatives of any crop species is a major objective in genetic improvement and crop breeding programs. The timing of onset of flowering is also crucial to reproductive success of flowering plant. Flowering pattern in five species in the genus Theobroma and oneHerrania spp. was studied over a 10 year period in Nigeria. Results showed that although at different intensities, flowering incidence was observed in Theobroma cacao in all the months of the year. In Theobroma microcarpum and Theobroma bicolor, flowering commenced at the onset of dry season in November / December and ceased at the end of the second module of rainfall. In Theobroma speciosum and Theobroma grandiflorum, flowering was mainly confined to the dry period between December and April. However, inHerrania spp., flowering occurred mainly during rainy season. Flowering incidence in Herrania spp. was significantly negatively (r = –0.906, P < 0.0001) correlated with duration of sunshine hours but significantly positively (r = 0.743, P < 0.004) correlated with rainfall. On the other hand, flowering in T. speciosum was significantly positively (r = 0.655, P = 0.015) correlated with duration of sunshine hours but negatively (r = – 0.743, P = 0.003) correlated with rainfall. Flowering in T. grandiflorum was in direct antithesis of the bimodal rainfall pattern observed annually. Key words: Theobroma, inter-specific hybridization, flowering time, pollination.