Emmanuel Youmbi

Spectrum of melliferous plants used by Apis mellifera adansonii in the Sudano‐Guinean western highlands of Cameroon

The frequency and intense usage of melliferous plants by Apis mellifera adansonii is documented through the melissopalynology analysis of 30 honey samples collected between September 2002 and March 2003 in the Sudano‐Guinean western highlands of Cameroon (LN 5°21.45′–5°35.44′ and LE 10°04.72′–10°26.24′). A diverse spectrum of 88 genera from 46 families was identified from pollen in the honey samples. The most common were members of the Asteraceae, Euphorbiaceae and Myrtaceae. The frequency of utilisation of melliferous plants is grouped into three categories: most frequently gathered melliferous plants (e.g. Eucalyptus, Coffea, Bidens and Terminalia); averagely gathered melliferous plants (e.g. Elaeis, Phoenix, Lannea and Julbernardia) and less frequently gathered melliferous plants with pollen present in less than 30% of honey samples (e.g. Salix, Casuarina and Pterocarpus). The most intensively utilized species by Apis mellifera adansonii represent 22.7% of the genera from 16 families. Pollen of only 8.0% of the taxa appeared as predominant in the honey samples and these belonged to six families. Eucalyptus was the only genus which had pollen that was predominant, important minor and minor in honey samples. Sixty percent of honey samples were unifloral for Eucalyptus and Helichrysum whilst the remaining 40.0% were multifloral.

Morphologie et germination in vitro du pollen de Dacryodes edulis (Burseraceae)

Letude de la morphologie du pollen de Dacryodes edulis a montre quil est: isopolaire, tricolpore, longiaxe et possede une exine epaisse qui le predispose a une conservation a long terme. La germination in vitro est optimale sur le milieu de Brewbaker et Kwack additionne de 15 ou 20% de saccharose a pH 5,3. Lincubation se faisant a lobscurite et a 30°C, la germination est rapide, pres de 60% des pollens germent apres une heure dincubation, mais un temps superieur a trois heures est necessaire pour avoir une germination optimale et une elongation maximale du tube pollinique. Le pouvoir germinatif est de 8% apres 24 mois de stockage a—20°C. A study of the morphology of pollen of Dacryodes edulis has shown that it is: isopolar, tricolporate, prolate. The structural characteristics of the exine show the possibility for long‐term pollen storage. In vitro germination is optimal on Brewbaker & Kwack medium containing 15 or 20% sucrose at pH 5,3. Incubation is carried out at 30°C in the dark. Germination is v...

Genetic architecture of some leaf yield and quality attributes in dual-purpose cowpea (Vigna unguiculata L. Walp.).

Aims: Cowpea’s use as leafy vegetable has been widely neglected in research. The present study was aimed at finding out the nature and magnitude of genetic variability in dual-purpose cowpea for leaf yield and quality attributes. Place and Duration of Study: Ngaoundere University (Cameroon), from 2008 to 2009. Study design and Methodology: Fourteen pure lines and ten F1 hybrids derived from a 5 x 5 half-diallel cross were grown in Randomized Complete Block Design (RCBD) with three replications to assess the genetic mechanism of leaf yield index (LYI), leaf area (LA), leaves per plant (NLP), leaf protein (LN) and phosphorus (LP) content. Results: Analysis of variance indicated significant differences (p<0.01) among genotypes for all traits. Moderate to high heritability in broad-sense (0.49-0.90) was recorded for the characters indicating major role of genetic variance in the expression of these polygenic traits. Diallel analysis showed significance (p<0.05) of the effects of general combining ability (GCA), specific combining ability (SCA), the involvement of additive and dominance genes. These genes were asymmetrically distributed among the parental genotypes. Dominant genes had an overall positive effect for leaves per plant, leaf yield index and phosphorus content while high protein content and surface area appeared to be associated Research Article American Journal of Experimental Agriculture, 1(4): 400-413, 2011 401 mostly with recessive genes. Correlations between the leaf attributes and seed yield components were significant only for leaves per plant and seeds per pod (-0.73), pods per plant (-0.69); leaf yield index and seed weight (0.69); leaf protein content and pods per plant (-0.77). Conclusion: These results could be exploited in breeding programs to develop nutritional superior cowpea varieties which could be used for harvesting of both leaves and seeds.