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 RÉSUMÉ La production de grains de pollen non fonctionnels par les plantes réduit l'efficience de la pollinisation. Une étude avait été réalisée à l'Institut de Recherche sur le Cocoa au Nigéria, Ibadan afin de déterminer l'influence des précipitations et de la température sur l'intensité de la floraison des clones sélectionnés de haute-Amazonie cacao (Theobroma cacao), ainsi que la fertilité de son pollen. Huit clones de T. cacao utilisés avaient été T17/11, T7/12, T12/5, T86/45, C23, C64, de C77, ainsi que Pa 24. Le nombre de fleurs à divers endroits avait été compté. Les anthères avaient été écrasés dans l'acetocarmine et examinés au microscope afin de déterminer la fertilité du pollen pour chaque clone. Le résultat a montré que l'intensité la floraison avait été réglementée par les précipitations et la température dans T. cacao, et elle variait parmi les huit clones étudiés. Le nombre de fleurs produites par les divers clones allant de 128 pour le clone C23, à 415 pour T86/45 clone aussi bien en janvier qu'en mai. Le nombre de fleurs produites sur la surface ventrale (V) de clones était significativement plus élevé (p < 0.05) que celle de la partie dorsale, par conséquent, plus de gousses par tampon auraient été produites si la plupart de fleurs produites sur la partie dorsale (inférieure ou abaxial) sont pollinisés par les pollinisateurs dans le jardin semencier. Le clone T86/45 avaient la viabilité du pollen plus élevée (92,11 %). Le clone T12/5 a enregistré la viabilité du pollen le plus bas (81.06 %).Mots Clés: Floraison du cocoa, Theobroma cacao, Haute-Amazonie S. S. OMOLAJA et al. 42

Knowledge of genebank and on-farm genetic diversity, particularly in an introduced crop species, is crucial to the management and utilization of the genetic resources available. Microsatellite markers were used to determine genetic diversity in 574 accessions of cacao, Theobroma cacao L., representing eight groups covering parental populations in West Africa, genebank, and farmers' populations in Nigeria. From the 12 microsatellite markers used, a total of 144 alleles were detected with a mean allelic richness of 4.39 alleles/locus. The largest genetic diversity was found in the Upper Amazon parent population (H nb =0.730), followed by the 1944 Posnette's Introduction (H nb =0.704), and was lowest in the Local parent population (H nb =0.471). Gene diversity was appreciably high in the farmers' populations (H nb =0.563-0.624); however, the effective number of alleles was lower than that found in the genebank's Posnette's population. Fixation index estimates indicated deficiency of heterozygotes in the Upper Amazon and the Local parent populations (F is = 0.209 and 0.160, respectively), and excess of heterozygotes in the Trinitario parent population (F is =−0.341). The presence of inbreeding in the Local parent populations and substructure (Wahlund effect) in the Upper Amazon were suggested for the deficiency of heterozygotes observed. Non-significant genetic differentiation observed between the genebank's and farmers' populations indicated significant impact of national breeding programs on varieties grown in farmers' plantations. From this study, we showed that appreciable genetic diversity was present in on-farm and field genebank collections of cacao that can be exploited for crop improvement in West Africa. Suggestions for future conservation of on-farm genetic diversity and local landraces are further discussed.

Predicting the behavior, fate, and transport potential of a herbicide in any soil involves understanding the sorption characteristics. The sorption characteristics of glyphosate (GPS) on soil and their main components were investigated, indicating that the mineral phase is more important than the organic carbon in adsorption of GPS. Sorption isotherms were determined from each component using the batch equilibrium method at various concentrations (5, 10, 15, 20, 25, and 30 mg L −1 ) and sorption affinity of GPS was approximated by the Freundlich equation. The sorption strength K f [mg kg −1 (L mg −1 ) −n ] across the various components ranged from 2.1-134.9 while the organic carbon-normalized Freundlich sorption capacity values, K foc , ranged from 1.28-3.53 mg kg −1 -OC/(mg L −1 ) n . Infrared Fourier transform spectroscopy (FTIR) of the components showed significant structural differences. The results suggest that the presence of the oxides and hydroxides iron, in particular in soil solutions, enhanced GPS adsorption. They also suggest that reduction in OC% due to various treatments may enhance the remobilization of GPS into the aqueous phase (i.e., groundwater), though at different rates. Comparatively, contribution of surface area to the adsorption of GPS on the various components proved more significant than contents of organic carbon.

Genetic architecture reflects the pattern of effects and interaction of genes underlying phenotypic variation. Most mapping and breeding approaches generally consider the additive part of variation but offer limited knowledge on the benefits of epistasis which explains in part the variation observed in traits. In this study, the cowpea multiparent advanced generation inter-cross (MAGIC) population was used to characterize the epistatic genetic architecture of flowering time, maturity, and seed size. In addition, consideration for epistatic genetic architecture in genomic-enabled breeding (GEB) was investigated using parametric, semi-parametric, and non-parametric genomic selection (GS) models. Our results showed that large and moderate effect–sized two-way epistatic interactions underlie the traits examined. Flowering time QTL colocalized with cowpea putative orthologs of Arabidopsis thaliana and Glycine max genes like PHYTOCLOCK1 ( PCL1 [Vigun11g157600]) and PHYTOCHROME A ( PHY A [Vigun01g205500]). Flowering time adaptation to long and short photoperiod was found to be controlled by distinct and common main and epistatic loci. Parametric and semi-parametric GS models outperformed non-parametric GS model, while using known quantitative trait nucleotide(s) (QTNs) as fixed effects improved prediction accuracy when traits were controlled by large effect loci. In general, our study demonstrated that prior understanding of the genetic architecture of a trait can help make informed decisions in GEB.