A new process to promote the use of controlled mycorrhization practice in forest nurseries

The aims of this study were to test a new mycorrhizal inoculation process using a “catalyser” of the mycorrhizal establishment (termite mounds of Macrotermes subhyalinus) to minimize the requested volume of fungal inoculum added to the cultural substrate. The effects of the termite mound were explored on mycorrhiza formation between an Australian Acacia, Acacia holosericea and an ectomycorrhizal fungus or an arbuscular mycorrhizal fungus using a two-step cultural system. The first step of this cultural practice was the inoculation of A. holosericea seedlings in small soil volumes (5 L plastic containers planted with 100 pre-germinated seeds) whereas the second one allowed the development of these mycorrhized plants in larger soil volumes (1 L pots planted with one seedling). Termite mound amendment significantly enhanced the mycorrhizal formation from both types of fungal isolates. This stimulating effect could probably be attributed to the introduction via the termite mound of a bacterial group (that is, fluorescent pseudomonads) that could act as Mycorrhiza Helper Bacteria (MHB). Since it is possible to reduce the requested fungal inoculum in controlled mycorrhization practice using M. subhyalinus mound powders, this biotechnological process could be useful in re-afforestation of tropical regions by lowering the requested fungal inoculum quantities and reducing the financial costs of controlled mycorrhization in forest nurseries

Variability in seed traits, oil content and genetic diversity in local and exotic accessions of Jatropha curcas L. in Senegal

Variability in seed traits, oil content and genetic diversity of Jatropha curcas L. according to rainfall gradient in Senegal are hereby reported and discussed. Seed oil variability ranged from 58.61% in Sudanian zone to 46.94% in Sahelian zone. Seed oil content and seed thickness were correlated to rainfall with a correlation coefficient of 0.62 and 0.48 respectively. However, seed length, breadth and 20 seed-weight were not correlated to rainfall. The random amplification of polymorphic DNA (RAPD) primers used to assess genetic variation showed a clear polymorphism. The mean polymorphism rate was 42.68%. A low variability was observed in the accessions. The genetic diversity was not correlated to geographic position. On the basis of coefficient similarity values, the accessions were genetically diverse. Cluster analysis based on similarity values classified Jatropha curcas L. accessions into three major clusters of which cluster I was the largest group. The lowest genetic distance (0.029) was recorded between Karang and Kaffrine accessions whereas the highest genetic distance (0.274) was observed between Bignona and Karang accessions. Accession from Bignona recorded the highest intra-population variation. Special attention must be accorded to accessions with high oil content, seed weight and high intra-population variation for future selection programs.Keywords: Jatropha curcas L., seed size, oil content, genetic diversity, Senegal.African Journal of Biotechnology Vol. 12(34), pp. 5267-527

Hernies Ombilicales Étranglées De L’enfant Au Centre Hospitalier Régional De Ziguinchor (Sénégal)

The umbilical hernia is a well-known pathology even though, its strangulation has been subject to much controversy. The aim of this work is to report our experience in the management of strangulated hernia of the child at the Ziguinchor regional hospital and to compare our results with those of the literature through a retrospective and descriptive study over a four years period. During the study period 24 patients with high male predominance were received. The mean age of the patients was 2.1 years. 45% of patients had a chronic cough. The average time for consultation was 27.6 hours. A notion of abdominal abrupt was found in 45% of the cases. The vast majority of patients arrived at the hospital during the dry season. Abdominal pain and vomiting were the main symptoms. An occlusive syndrome was present in about half of the patients. The diameter of the collar of the hernia varied between 1.5 and 2.5 cm and no intestinal necrosis was found during exploration. The surgery was simple in the majority of cases. Umbilical hernia is a reality in under-developed environment some factors promotes its complications

Effect of eucalyptus (Eucalyptus camaldulensis) and maize (Zea mays) litter on growth, development, mycorrhizal colonization and roots nodulation of Arachis hypogaea

In Senegal, farmers often cultivate groundnut in association with eucalyptus plantations to increase their incomes. However eucalyptus plantations produce large amounts of litter, which impact on groundnut has not been clearly elucidated yet. In order to investigate litter accumulation effect on growth, development, and groundnut root infection by arbuscular mycorrhizal fungi (AMF) and rhizobia, a greenhouse experiment was performed. The effect of eucalyptus litter was compared to that maize litter effect at three litter amendments (0, 1 and 5%). Chemical analysis showed that eucalyptus litter differed essentially from maize litter by its high polyphenols content and lower pH. At high amendment (5%), root nodulation and mycorrhizal colonization were significantly reduced with eucalyptus litter whereas no significant differences were observed with maize litter. In addition, groundnut growth, number of flowers per plant, pods yield and leaf mineral contents (N and C) were significantly lower for plant grown in soil highly amended with eucalyptus litter. Plants showed deficiency of chlorophyll content in leaves and were less vigorous compared to treatments without amendment and those amended at 1% level. For all parameters measured, plants grown in soil lowly amended (1%) and plants grown in control treatment did not significantly differ.Key words: Litter, Eucalyptus, Arachis hypogaea, Mycorrhizal symbiosis, Rhizobia

Diversity of indigeneous bradyrhizobia associated with three cowpea cultivars (Vigna unguiculata (L.) Walp.) grown under limited and favorable water conditions in Senegal (West Africa)

The diversity of Bradyrhizobium strains nodulating three cowpea (Vigna unguiculata L. Walp.) cultivars in favorable and water-limited conditions occuring at flowering was analysed. PCR- Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of 16S-23S rDNA intergenic spacer region (IGS) directly applied on 85 crushed nodules distinguished four genetic profiles, IGS types I, II, III and IV. The distribution of these IGS types according to water conditions and cowpea cultivars (B-21, TN 88-63 and Mouride) showed that nodulating strains appeared more diverse in water-limited condition. More than three quarters of prospected nodules presented the IGS type I. They were formed on all three cultivars and in both water conditions. Only a small part of nodules was distributed between the IGS type II, III and IV. Nodules showing the IGS types II and III were found mainly in limited conditions on TN 88-63 and Mouride cultivars, whereas nodules presenting the IGS type IV were collected only from cultivars B-21 and Mouride, in both water conditions. Strains corresponding to the different profiles were isolated. The phylogenetic analysis of 16S rRNA gene sequences showed that they belong to the genus, Bradyrhizobium. The sequence analysis of 16S-23S rDNA IGS revealed that the strains exhibiting IGS types II, III and IV were closely related to some Faidherbia albida isolates from Senegal. IGS type II can be assigned with at least 98% similarity to Bradyrhizobium genospecies IV. IGS types III and IV showed more than 96% similarity with genospecies VII and could belong to the same genospecies. IGS type I, the most frequent, exhibits low IGS similarity with reported sequences in the databases, and could represent a new genospecies. (African Journal of Biotechnology: 2003 2(1): 13-23