Abstract
The probable role of within-pod microenvironment on seed sizes, seedling vigour and biomass yield of four cocoa genotypes was investigated for two years. The respective main, sub and sub-sub plots in the split-split plot experimental design were years, genotypes and within-pod bean positions. Data were taken on cocoa bean length, width and thickness after each pod was opened. Four weekly periodic data were obtained for plant height (PH), stem girth (SG) and number of leaves (NOL); root and shoot biomass yield were also recorded. Analysis of variance revealed significant (p ≤ 0.05) bean position, genotypes, years and some interaction on the studied traits. Means of the levels of the three factors differed significantly (p ≤ 0.05). Proximal, middle and distal positions were distinct within-pod microenvironments. The pod middle cavity housed the longest, widest and heaviest beans. Trend analysis of the growing sequences of NOL, PH and SG by the four genotypes differed with bean locations. For bean length, GGE biplot respectively identified CRIN Tc1, CRIN Tc2 and CRIN Tc3 as the best genotype for middle, proximal and the distal positions. The intra-locular space within the pod enhanced differential seed development and maturation; this was evident in the seedling vigour.
Highlights
Cocoa (Theobroma cacao L.), a native crop of South America is well adapted to and flourishes productively in the rainforest ecology of West and Central Africa
With an interest to understand the relative differential performances of cocoa seeds, usually called beans in the different localized positions within the fruit capsules called pods of different cocoa genotypes and the possible link of the same to seedling vigour and development; a research was conducted for two consecutive years at the Cocoa Research Institute of Nigeria (CRIN), Idi-Ayunre, Ibadan, Nigeria
Our work clearly revealed that the three inner locations along cocoa pods length are prominent in distinguishing cocoa bean sizes; identifying the cocoa beans in the middle of the pod to be of the highest quality for all the metric measurements including bean mass
Summary
Cocoa (Theobroma cacao L.), a native crop of South America is well adapted to and flourishes productively in the rainforest ecology of West and Central Africa. Among the four major cocoa producing member states in the West and Central Africa, production in Nigeria is at the last place. This has grossly being attributed to low yield from most farmers’ field. Mathew et al (2012) identified the use of low quality seed for raising seedlings, low emergence and poor seedling vigour as some of the factors responsible for low productivity within the plantation. Cocoa beans meant for propagation to raise seedlings are expected to have completed their structural and functional development within the pod (the fruit) before they are plucked for use in raising seedlings (Opoku-Ameyaw et al, 2010)
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