Annual Research & Review in Biology

In an attempt to obtain biological control agents for fusariose wilt, a total of 54 endophytic bacterial strains were isolated from the root of plants Urtica dioica and screened for in vitro antagonist activity against Fusarium oxysporum. Among the 54 bacterial isolates, 27 isolates exhibited more than 60% inhibition of mycelia growth of Fusarium oxysporum. The strain R19 which exhibited the most obvious antagonistic activity was selected for greenhouse studies. The SR19 had no pathogenicity and was identified as Paenibacillus polymyxa based on its phenotypical and biochemical properties as well as its 16S rRNA gene sequence.

Growth chamber studies resulted in statistically significant increases in inoculating tomato seedling with the endophytic strain SR19 which in turn resulted in improving plant seedling stand by 32%   and increasing fresh weights of root and fresh weight of aerial biomass of plants over the untreated pathogen control by 6.95 g and 7.96 g, respectively.

Strain SR19 is a potential biological control agent that may contribute to the protection of tomato plants against fusariose wilt.

Rhizoctonia solani Kühn [teleomorph: Thanatephorus cucumeris (Frank) Donk.] is an important fungal pathogen widespread in all potato growing areas of the world that causes stem canker and black scurf of potato (Solanum tuberosum L.).

The aim of this study was to find a simple and reliable technique for determining the pathogenicity of Rhizoctonia solani isolates. Sixty (60) isolates of R. solani obtained from sclerotia on potato tubers, collected from different market of Agadir and Casablanca regions (Morocco), were studied for their morphology, pathogenicity and molecular characteristics. They were morphologically characterised by the production of sclerotia and moniloïd cells, and by the mycelium growth capacity at 15, 20, 25, 30 and 35°C. This morphological characterisation leads to three groups of isolates. The first group contained P01 and P03 isolates, which were able to develop under 35°C. However, under 25°C, they did not develop sclerotia. The second group, only formed by L17.1 isolate, did not form sclerotia under 25°C and was not able to develop under 35°C. The third group, formed by several isolates, developed sclerotia under 25°C conditions and were not able to grow under 35°C. Also, a positive correlation was consistent between the production of sclerotia and moniloïd cell formation. The anastomosis reaction revealed that P01, P03, L17.1, and L4.1 isolates were identified as AG-4 and for the other isolates as AG-3. The pathogenic characterisation has shown that P01, P03, L4.1, and L17.1 isolates caused important damping off of radish, tomato, beans, zucchini, and melon. However, the other isolates showed only a minor damping off rate. Molecular characterisation confirmed the classical anastomosis grouping of the isolates into AG-3 and AG-4 Anastomosis Groups. The molecular characterisation is the most rapid and reliable technique to determine the anastomosis group of unknown isolates. The three tests including the pathogenicity, the cultural anastomosis grouping, and the molecular method helped to separate the studied isolates to two groups AG-3 and AG-4.

The quality of potable water depends not only on its physical and chemical characteristics but also on its biological characteristics. Potable water is often sourced from surface water, mainly rivers, streams, lakes and groundwater - boreholes and wells; of which boreholes are supposedly superior. In the present study, the physicochemical and microbiological status of six newly drilled boreholes in Rafi Local Government Area, Minna, Niger State was assessed. Twenty-two physicochemical parameters and coliform count were determined. Water samples were collected from newly drilled borehole water sources in Tsofomension 1, TsofoMension 2, Katako, Tunga Bako, Kagara and Kwana. The colour, odour, taste, temperature, turbidity, conductivity, pH, chloride and copper ions were within acceptable limits. Iron and manganese content of the three regions were highly elevated above the recommended level. It is of concern that the level of hydrogen sulphide (0.2 - 0.27) was far above the permissible level (0.05), being newly drilled sources of water. Only one of the studied boreholes was free of both total and faecal coliforms, other boreholes were contaminated with either total or faecal coliforms or both. The findings in this study necessitate a call for increased hygiene and construction of lined soak-away to eradicate indiscriminate discharge of human and animal wastes. Appropriate water treatment methods such as coagulation, filtration and boiling of water should be encouraged. Most importantly, newly dug water sources should be tested, monitored and elaborately treated before consumption.

The effect of composite endomycorrhizal inoculums was studied on the strawberry plant growth under greenhouse conditions. After six months, a significative effect was observed. Leaves number, fruits number, fresh roots weight and fresh fruits weight under greenhouse conditions compared to controls were 28.9/11.2, 58/1, 12.59g/9.62g and 367g/230g. Mycorrhizal intensity, arbuscular content and spores number in mycorrhized and non mycorrhized strawberry seedlings were respectively 54.1, 28.3 and 220. The spores detected belong to eight species and four genera: Glomus, Rhizophagus, Gigaspora and Scutellospora.

Bean is an annual legume, consumed by more than 500 million people worldwide. It is a base in their daily diet because of its high protein content (25-30%). In Cameroon, its culture has many problems, including the significant decline in fertility and soil acidity. This study aimed to evaluate the effect of organo-mineral fertilization on the bean production. The experimental design was a complete randomized block with two factors [varieties (NITU and DOR 701) and treatments (T0: control, T1: poultry manure and T2: NPK)] and three replications. The study was carried out at the second cropping season from August to November 2015 in Eloumden in the Mefou and Akono Division, Centre Region (Cameroon). The organo-mineral fertilization of two new varieties of beans was tested. The collar diameter, the number of leaves and the shoot length were evaluated weekly. At harvest, the nodulation and yield were evaluated. The results showed that treatment with poultry manure (T1) induced a very highly significant growth (P ˂ .001) of shoot length, as well as a significant increase in the number of pods (36 ± 5.91), the number of seeds (142 ± 88.07) and the biomass. The chemical fertilizer treatment (T2) induced the best nodulation (25.50 ± 0.87). The treatments did not influence the seed yield. However, the varietal effect was highly significant. DOR 701 had a higher seed yield (5.91 ± 1.03 t ha-1) than the NITU variety (4.19 ± 0.54 t ha-1). Poultry manure (T1) restores the minerals useful for the next crop. It is therefore recommended because of its best yield and its ability to protect the environment.