Tropical soils are highly leached, abundantly clayey and strongly acid, resulting in low mineral availability and especially phosphorus (P). The plants of this region must establish symbiotic relationships enabling them to strengthen their hydromineral nutrition. The aim of this work was to study the effect of P fertilizer application on the diversity of arbuscular mycorhizal fungi (AMF) under the rhizosphere of three Bambara groundnut (Vigna subterranea) landraces. To attain it, plants were grown in farm under different simple superphosphate (SSP) levels (0, 50, 100, 150 and 200 kg.ha-1 P 2 O 5) in 2015 at Mendong and Soa districts. Experimental units were arranged in a randomized complete block design with three replications. Soil and root samples were taken from the rhizosphere of three randomly selected seeds holes per experimental unit at flowering (31 days after sowing) and fruition stages. At harvest, the roots were stored in 50% ethyl alcohol. They were stained with methyl blue and observed under an optical microscope. The soil samples allowed the trapping to be carried out in a greenhouse with sorghum as test plants. Results show that Bambara groundnut landraces were the host of several AMF species and were highly colonized with all showing hyphae, vesicles and even spores. High level of SSP (200 kg.ha-1 P 2 O 5) significantly (p<0.001) reduced the intensity of mycorrhization as well as the diversity indices compared to the control. A density of AMF spores reaching 1930 was obtained in 100 g of trapping substrate. On the basis of morphological characteristics, 16 AMF species belonging to nine genera (Glomus, Acaulospora, Gigaspora, Racocetra, Rhizophagus, Funneliformis, Septoglomus, Diversispora and Claroideoglomous) were isolated and identified. Rhizophagus intraradices and Septoglomus constrictum were the most abundant. AMF species identified in this groundnut rhizosphere can be multiplied and used as biological fertilizer to increase its yield.

The study of pollen dispersal and mode of fertilization of Vernonia amygdalina and Vernonia calvoana is a prerequisite to the understanding of genetic diversity and elaboration of improvement programs for the Vernonia genus. In this study, precise experimental designs were made for morphological and biological observations on Vernonia species capitulum in order to assess the distinctive effects of each of the three possible pollen transportation agents (insects, wind and rain water) on pollination. Results obtained show that the exclusive mode of pollen dispersal is entomophilous. Even though allogamy and autogamy are observed as two possible modes of fertilization in Vernonia spp., some arguments tend to favour allogamy. However, there is no clear cut position on the issue, hence the need for confirmation by further experimentation in controlled pollination. This study paves the way for the establishment of a genetic improvement program for this genus based on the results on pollen dispersal.

The objective of this study was to test for appropriate quantity of fertilizer (NPK 12-11-18) required to boost the production of cassava (variety TME 419) in the forest zone of Cameroon. The trial was conducted at the experimental farm of the Institute of Agricultural Research for Development (IRAD) in Mbalmayo. The experimental design was completely randomized block design in three replicates. The treatments were as follows: T0 (Control (No input)); T1 (200 kg.ha-1); T2 (300 kg.ha-1); and T3 (400 kgha-1). The data were analyzed using the IBM SPSS Statistics 20 Software. The results showed that chemical fertilizer improves the growth (number of leaves, plant height, and petiole length) and yield (number of marketable root, yield) of cassava mainly because it enhances soil nutrient availability. Thus, NPKfertilizer significantly (p<0.001) increased petiole length by 20.71, 27.83, and 31.62% for T1, T2, and T3, respectively at 5 months after planting (MAP). The highest plant height and number of leaves at 4 and 5 MAP was observed with T3 followed by T2 and T1. Similarly, the highest root yield (43.33±10.97 t.ha-1) was observed with treatment T3. Hence, the fertilizer application rate of 400 kgha-1 of NPK 12-11-18 appears most appropriate for intensification of cassava production in the humid forest agro ecological zone of Cameroon.

Aquaculture in the form of fish farming was introduced in Cameroon in 1948. But, it still remains marginal. The population's demand is estimated at more than 400,000 tones, but production is still insufficient to meet this demand.Indeed, the contribution of fisheries and aquaculture is less than 1% of GDP and those of aquaculture less than 0.1%. However, aquaculture is the fastest growing food production sector in the world. Research being the basis and the backbone of development, this review is an inventory of works of aquaculture research in Cameroon. To the most popular species (common carp, North African catfish and tilapia) is added today a dozen of endemic species. The research has been concerned in recent years with fry production, nutrition, composition, domestication of fish and also their parasites. Important work have also been done on the intensification of fish farming, the use of agricultural by-products in aquaculture, the promotion of integrated aquaculture and on the potential negative impacts of fish farming on the prevalence of diseases and on the environment. It also placed particular emphasis on the constraints of fish farming in Cameroon, particularly on the difficulty of adoption of new farming innovations, the relative profitability of fish farming, the need for support to fish farmers, the relation research-farmer, the financing of fish farming, and many other constraints. This basic work already done by research can be improved. It will thus be able to contribute in reducing the large deficit of Cameroonian aquaculture production.

Soil acidity, combined with high aluminum toxicity, is one of the major problems limiting agricultural productivity. The objective of this work was to improve growth and yields of okra on acidic and degraded soil in the Center region, Cameroon, using an innovative fertilization approach and lime material. The soil is ferralitic, very acidic, with aluminum toxicity and significant imbalance in the (Ca/Mg/K) ratio of (55/15/30). Seven fertilization treatments were applied: Control without fertilizer; arbuscular mycorrhizal fungi (AMF); AMF+50% poultry manure (AMF+½ PM); mineral fertilizers with cation balance at 100% (MF100 %); AMF+50% mineral fertilizers (AMF+50 % MF); poultry manure at 50%+50 % mineral fertilizers (MF50%+½ PM) and poultry manure (PM). Two varieties of okra were used (Kirikou F1 and Local). The experimental design was a split-plot with two factors. Considering MF, an innovative Ca/Mg/K ratio of 68/23/9 was applied. The results showed that the applied fertilizers had a significant effect on the agronomic parameters of okra with MF50%+½ PM followed by PM and MF100% as the best treatments. An average increase in fresh yield from 111% to 1840% over the control was recorded and the best symbiotic parameters were observed at the AMF treatment associated with the Local variety. This variety responds better to organic matter intake while Kirikou F1 is more favorable to chemical fertilizer addition.