In vitro Proliferation Ability of Axillary Buds in Musa spp

Tissue culture method has always considered the apical bud as the initial explant for micropropagation of plantain until recently where it was shown with the variety Big Ebanga that axillary buds could equally serve as initial explant. As axillary buds have shown mass propagation abilities in Big Ebanga, this explant is tested in other banana varieties to confirm performances already observed. Axillary buds and shoot tips excisedfrom : Pisang Mas (AA), Grande Naine (AAA), Batard and French Clair (AAB), CRBP 39 (AAAB) and Pelipita (ABB) varieties were used as explants. The proliferation rate of Axillary and apical buds and other growthparameters were measured. Results showed that no significant differences were observed between the two types of buds after four to five sub cultures in all the varieties except for CRBP 39 where the axillary bud exhibitsa higher proliferation rate. Concerning the frequency of leaf emission, the diameter and the height of the pseudostems, no significant differences were obtained between plants derived from the two types of buds during the weaning and hardening phases. In conclusion, axillary buds proliferated for all varieties tested regardless of the genomic group. Plantlets obtained from the two types of buds showed similar performanceduring the weaning and hardening phases. The axillary bud can thus be used as initial explant for micro propagation in Musa sp.Key words : Musa sp., micropropagation, axillary buds, shoot tips, genomic group.Le bourgeon terminal a été longtemps considéré comme explant initial de micropropagation chez le bananier. Récemment, il a été montré chez le cultivar Big Ebanga que le bourgeon axillaire pouvait aussi servir d’explant primaire. Ce résultat peut-il être transposé à d’autres variétés ? Les bourgeons apicaux et axillaires des variétés : Pisang Mas et Grande Naine (AAA), Batard et French Clair (AAB), CRBP 39 (AAAB) et Pélipita (ABB) ont été utilisés comme explants. Le taux de prolifération, et certains paramètres quantitatifs ont été mesurés. Les résultats obtenus montrent qu’il n’y a pas de différences significatives entre les deux types de bourgeon après 4 à 5 subcultures chez la plupart des cultivars sauf chez l’hybride CRBP 39 qui présente un taux de prolifération supérieur à celui obtenu chez le bourgeon terminal. Quant aux autres paramètres de croissance : émission de feuilles, diamètre et hauteur des pseudo-tiges, des différences significatives ne sont pas observées entre les plants issus des deux types d’explants (bt, ba) pendant les phases de sevrage et d’élevage. Il y a une prolifération du bourgeon axillaire chez toutes les variétés étudiées et appartenant à différents groupes génomiques du bananier. Les plantules issues des deux types de bourgeons croissent de manière identique pendant les phases de sevrage et d’élevage. Le bourgeon axillaire peut donc être utilisé comme explant primaire de micropropagation chez Musa sp.Mots clés : Musa sp, micropropagation, bourgeons axillaires, bourgeons terminaux, groupe génomique. Article in English

Conservation des pollens de deux plantes mellifères (Vitellaria paradoxa et Steganotaenia araliacea) de la région de l'Adamaoua Cameroun

Conservation of Pollens of Two Honey Species (Vitellaria paradoxa and Steganotaenia araliaceae) in the Region of Adamawa (Cameroon). The Adamaoua Region of Cameroon is a significant apiculture zone. The threats on the plant bioversity of this zone calls for the conservation of pollens, which in turn is necessary for the improvement and conservation of melliferous plants. Permanent maintenance of the flora is essential in research where pollens serve as base of plant material. In order to optimize conservation parameters of pollens of the two melliferous plants threatened (Vitellaria paradoxa and Steganotaenia araliaceae), in vitro tests (base medium, sucrose concentration, temperature, pH), dehydration time, and then storage of pollens in the fridge (+ 10 °C) as well as in the freezer (- 20 °C) were carried out. According to the results, pollen of the two plant species showed high germination rate in the Heslop-Harrison medium supplemented with 10 and 15% sucrose respectively for V. paradoxa and S. araliaceae. The optimum germination rates (39% and 20%) were obtained respectively at pH 5.6 and 5.9 while optimum temperature was at 30 °C. Pollen of S. araliaceae were more tolerant to dehydration 8 weeks after drying in a desiccator containing silice grains. Pollen of two species still germinated more than 1% after 8 weeks of storage in the freezer. One week dehydration considerably extended storage period of pollens of the two plant species compared to the control. In the defined conditions, pollen grains of the two species can be stored for future use in plant breeding programs

Influence du mode de pollinisation et des caracteristiques des fruits semenciers sur la capacite germinative des graines du papayer solo

La graine est l’organe principal de propagation du papayer (Carica  papaya), chez qui les problèmes de germination sont récurrents.  L’influence du mode de pollinisation et de la conservation des papayes surla qualité de leurs semences est étudiée. Six cents fleurs hermaphrodites, de la lignée Solo n°8, sont marquées au stade ultime de bouton floral ; une moitié des fleurs est ensachée pour permettre l’autofécondation et l’autre, pour la pollinisation libre, laissée sans protection. Chaque semaine après l’ultime stade de bouton floral (SAUSBF), 10 fruits obtenus de chaque mode de pollinisation sont récoltés pour en extraire les semences. Les graines de certains fruits sont extraites après récolte et pour d’autresaprès des jours en conservation. Ces semences sont observées, pesées puis soumises à des tests de germination. Les premières graines  consistantes sont notées dans le fruit après 10 SAUSBF et celles capables de germer y sont signalées à partir de 14 SAUSBF. L’âge du fruit a  fortement influencé les performances des semences. Indépendamment du mode de pollinisation, la germination maximale est enregistrée avec les semences d’au moins 19 SAUSBF. La conservation des fruits a avancé la germination à 13 SAUSBF et offert les taux maximum aux semences dès 16 SAUSBF.Mots clés : Qualité semencière, papayer (Carica papaya L.), âge du fruit, conservation post-récolte, capacité germinative, pollinisatio

Influence du mode de pollinisation et des caracteristiques des fruits semenciers sur la capacite germinative des graines du papayer solo

La graine est l’organe principal de propagation du papayer (Carica  papaya), chez qui les problèmes de germination sont récurrents. L’influence du mode de pollinisation et de la conservation des papayes sur la qualité de leurs semences est étudiée. Six cents fleurs hermaphrodites, de la lignée Solo n°8, sont marquées au stade ultime de bouton floral ; une moitié des fleurs est ensachée pour permettre l’autofécondation et l’autre, pour la pollinisation libre, laissée sans protection. Chaque semaine après l’ultime stade de bouton floral (SAUSBF), 10 fruits obtenus de chaque mode de pollinisation sont récoltés pour en extraire les semences. Les graines de certains fruits sont extraites après récolte et pour d’autres après des jours en conservation. Ces semences sont observées, pesées puis soumises à des tests de germination. Les premières graines consistantes sont notées dans le fruit après 10 SAUSBF et celles capables de germer y sont  signalées à partir de 14 SAUSBF. L’âge du fruit a fortement influencé lesperformances des semences. Indépendamment du mode de pollinisation, la germination maximale est enregistrée avec les semences d’au moins 19 SAUSBF. La conservation des fruits a avancé la germination à 13 SAUSBF et offert les taux maximum aux semences dès 16 SAUSBF.Mots clés : Qualité semencière, papayer (Carica papaya L.), âge du fruit, conservation post-récolte, capacité germinative, pollinisation. GERMINATION OF PAPAYA SEED IN RELATION WITH THE AGE AND STORAGE OF FRUITPapaya is mostly propagated by seed, which highly fluctuates in quality. The effect of the pollination mode and that of post-harvest storage of fruits on the seed quality of papaya was investigated. 600 hermaphrodite flowers of Solo n°8 line were tagged just before their opening and the half was protected to insure selfpollination. Ten fruits were weekly harvested from each group to collect seeds at harvest or after storage. The weight and the germination capacities of the seeds were evaluated from  successive age of fruit. Results showed that no strong seedy structures arose in the fruits before 10 weeks and the first seeds capable to germinate appeared at 13 weeks. The age of the fruit at harvest had a strong effect on the weight and the viability of papaya seeds. Irrespective of the pollination mode, maximum germination rate started with seedsof 19 weeks. The softening of the fruit during a storage significantly  enhanced the germination behavior of seeds from younger fruits, leading to a maximum rate as from the age of sixteen.Key words : Seed quality, Carica papaya, fruit age, post-harvest storage, germination rate, pollination

Effet de la fertilisation minerale et organique sur le rendement en fruits du piment (Capsicum annuum L.; Solanaceae) en zone forestiere de basse altitude au Cameroun

A study on the effect of mineral and organic fertilizations on fruits yield of pepper (Capsicum annuum L.) was carried out in Cameroon. Three types of fertilizers: urea (46 %N), single superphosphate (16 %P2O5), and potassium sulphate (48 %K2O) were used alone, or in combination with each other and a bulk fertilizer NPK (19-4-16) was also formulated in order to optimize fruit yield. Poultry manure was used as organic fertilizer. During crop growth, plant height, canopy width, planting-flowering interval, flowering-fruiting period and the number and weight of fruits harvested were measured. The results show that bulking of the 3 single fertilizers, applied 4 times during the cropping period produced highly significant effects on all plant growth parameters. Significant differences were also observed on parameters of reproduction when NPK was applied 3 to 4 times during the cropping period. Furthermore, NPK, regularly broadcasted 4 times under plant canopy, gave the highest fruit yield. This latest treatment yielded the highest income and benefit-cost ratio. The organic fertilization had a higher fruit yield and higher benefit-cost ratio than many chemical fertilizer treatments.Keywords: Capsicum annuum L., fertilizer, formulation, fertilizationAgronomie Africaine 24 (3) : 231 - 240 (2012

Viabilité et développement végétatif des plantules de piment (Capsicum annuum L.) suivant différents matériels de conditionnement des semences

Germination and Seedling Development from Pepper (Capsicum annuum L.) Seeds following Storage in Different Packaging Materials. A study on the germination and seedling development from pepper (Capsicum annuum L.) seeds following storage in different packaging materials was carried out at the Institute of Agricultural Research for Development (IRAD), Njombe Multipurpose Research Station in Cameroon. Germination tests were conducted at 30 days intervals during 24 weeks of seed conservation in the laboratory at ambient temperature. Seeds were prepared from 4 pepper varieties (Safi, Big sun, Thailande and Local) and stored in 5 packaging materials (glass vial, plastic vial, laminated aluminium foil packet, paper and plastic envelope). The experiment was laid out in a 4 x 5 factorial design (4 varieties of pepper x 5 packaging materials) making 20 treatments in 5 replications. At each germination test, germinated seeds were counted everyday during 15 days. To estimate seedling development, 5 seedlings from each pepper variety issued from each packaging material was grown during each germination test in a polythene bag filled with local topsoil. Each sample was repeated 10 times. Thirty days after sowing, observations were made on seedling development parameters. The results obtained show that germination rate is higher immediately after seed preparation for all pepper varieties. Thereafter germination rate declines slowly when seeds are stored in laminated aluminium foil packets and rapidly when they are stored in paper and polythene envelopes. The other packaging materials occupy intermediary positions. Also, seedlings issued from seeds stored in laminated aluminium foil packets are more vigorous than those issued from seeds stored in paper and polythene envelopes during seed conservation period (6 months). The rapid loss of viability in pepper seeds stored in the two last packaging materials could be attributed to their permeability to air and humidity which accelerates seed ageing and deterioration

Genetic analysis of seed proteins contents in cowpea (Vigna unguiculata

In order to select cowpea genotypes with high food value, 10 varieties were genetically screened in Ngaoundéré (Cameroon) for seed crude protein and its soluble fractions contents. Five divergent lines were studied through a 5 x 5 half diallel cross mating. The genotypes presented a significant genetic variability for these parameters (p < 0.05). The globulins constituted the major seed protein fraction, followed by albumins. Diallel analysis demonstrated that, both additive and non-additive gene effects were responsible for the genetic variation of these traits. However, dominance variance was more important than additive variance for all traits. The model of over-dominance was most widespread, suggesting delayed selection to fairly good improvement. All these parameters were found highly inheritable (h2 = 0.68 to 0.83). The parents differed significantly for their general combining ability (GCA) and the F1 progenies showed specific combining ability (SCA). Dominant genes have positive effects for high levels of albumins, globulins and prolamins, while high percentage of seed protein and high glutenins content appeared to be associated with recessive genes. In the Guinea savannah zone, these results would help breeders to improve these biochemical traits in terms of initial parent selection and subsequent crossbred selection and breeding procedures.Key words: Vigna unguiculata, seed crude protein content, soluble protein fractions, diallel analysis, genetic improvement, Guinea savannah zone

Predominant melliferous plants of the western Sudano Guinean zone of Cameroon

Between September 2003 and March 2005, melissopalynological methods were used to access the predominant melliferous plants (PMP) in 104 honey samples collected from the Soudano Guinean highlands zone of west Cameroon. A total of 19 PMP from 11 families were identified, Asteraceae is the most represented. Trees and herbs were frequently exploited. Spontaneous PMP were more represented. Perennial PMP were highly visited by Apis mellifera adansonii. PMP with white colour flower are the most utilized by bees compared to other colours. When seasonal exploitation was considered, the proportion of PMP exploited in the rainy season was higher. Eucalyptus saligna, Terminalia mantaly and Pterocarpus soyauxii were frequently exploited.Key words: Apis mellifera adansonii, melliferous plant, predominant, harvested

Diversité floristique sous canopée en plantation forestière de Mangombe-Edea (Cameroun)

Floristic diversity under canopy in forest plantation of Mangombe-Edea (Cameroon). Trees plantation of Mangombe is situated in rain forest of low altitude. Six plots among which one of Mansonia altissima (A.Chev.) A.Chev., 2 of Lovoa trichilioides Harms, 3 of Terminalia ivorensis A.Chev. and one perturbed natural forest are concerned by this study. The work consisted to the evaluation of the floristic diversity under canopy in order to appreciate the influence of forest plantation on natural regeneration. A total of 26 families, 42 genders and 46 species were censured. Meliaceae and Apocynaceae are present in all the plots. In plot one of T. ivorensis, M. altissima and natural forest, the low value of equitability of Pielou traduces the dominance of flora by few species and the transitory situation of the ecosystem. On contrary the rest of plots present a good repartition of individuals among the species. One can notice a weak organization of the ecologic system in M. altissima plot, this corresponds to favourable conditions of environment for installation of many species represented by a few number of individuals. Shannon indices, relatively low in plot one of T. ivorensis characterize an ecosystem where one species is dominant. Globally, the regeneration under canopy is reconstituted progressively and remains less diversified than the nearest natural forest. Creation of genetic pool through selective entertainment under canopy will permit polycyclic management of plots for sustainable production of wood

Positive effect of in vitro embryo rescue on breaking the dormancy of wild banana seeds compared to direct sowing in the greenhouse

Introduction - The genetic diversity of wild bananas can conveniently be preserved in seed form. However, depending on the species and experimental sowing conditions, such seeds give uncertain, highly variable germination rates in the greenhouse. One hypothesis would be that the integuments of banana seeds contain dormancy factors preventing good germination when sown naturally. The aim of this work was to ascertain whether the germination rate for banana could be increased if embryos were removed from the influence of the integuments by culturing isolated embryos in vitro. Materials and methods - We present here our results for over 12,000 sowings of a vast panel of Musa acuminata and M. balbisiana genotypes grown in a collection at CARBAP in Cameroon. After harvesting at maturity from self-pollinated banana plants, fresh seeds were immediately sown on two contrasting sterile substrates in a greenhouse at CARBAP and were also cultured in vitro using embryos excised from the same seed batches. Results and discussion - We found substantial variations in germination percentages in the greenhouse depending on the genotypes studied. M. balbisiana seeds germinated well, with an average rate of 80%, or even peaks of 90% for some batches. On the other hand, the different M. acuminata accessions germinated poorly, suggesting dormancy factors in the seeds. We found that in vitro embryo culture eliminated all these differences between the genotypes, with a strong increase in germination rates for the genotypes studied. Conclusion - These results support the hypothesis that dormancy factors in Musa seeds are located in the seed integuments, rather than in the actual embryos. The implications of these results are numerous for collecting and managing batches of Musa seeds, and for conserving Musa genetic resources