No abstract

Soil fertility, growth, nutrient uptake and yield traits of peanut (Arachis hypogaea L. var. JL24) were investigated under two organic fertilizers (indigenous microorganisms (IMO) or effective microorganisms (EM) with three replications. Application of IMO or EM fertilizers had significant effects on soils fertility compared to untreated soils. Total nitrogen, organic carbon, total phosphorus, calcium and magnesium led to a significant increase under organic fertilizers. IMO fertilizer supply at 20 g significantly increased the shoot length and the number of leaves compared to the EM fertilizer and untreated plants. In contrast, the highest values of stem diameter and leaf area were recorded at 40 g of EM supply. The highest values of pod (1.25 and 1.18 t/ha) and grain yield (0.96 and 0.98 t/ha) were recorded at 10 and 20 g for IMO and EM, respectively. Application of EM and IMO at 10 or 20 g led to a significant increase in nitrogen and phosphorus contents in leaves and roots with the highest accumulation of nitrogen at the roots level of treated plants. Nitrogen and proteins contents of peanut seeds were positively influenced by IMO and EM supply at 10 and 20 g, respectively. The use of IMO and EM fertilizers could enhance peanut growth performance in sandy ferralitic soils.

Colocasia esculenta (L.) Schott is an important food for millions of people in countries of Africa, Asia andCentral America. The cultivation of taro suffers from an epidemic disease, the taro mildew, caused by P. colocasiae, which is a disease that manifests itself as oily and circular spots on tubers, stems, petioles and on taro leaves causing losses of more than 50% in less than ten days. This study was carried out to evaluate the impact of this pathogen on the leaf area parameter in two varieties of taro (Ibo coco and Atangana) at different water levels, then evaluate the incidence of the disease severity on the leaves at different water levels and study the behavior of this pathogen on plants previously inoculated with arbuscular mycorrhizal fungi (AMF) of the genus Gigaspora magarrita and Acaullospora tuberculata. The plants were separated into three batches (control batch not infected, batch infected with pathogen and batch not only infected but also inoculated with AMF at different water contents (500 ml, 370 ml, 250 ml and 125 ml), the batch infected with the pathogen alone showed a reduction in the growth parameters compared to the control, and the inoculated and infected batch also showed a reduction in growth parameters but closer to the control. In addition, the speed of propagation of the lesion in the inoculated batch is reduced compared to that of the uninoculated batch, and this speed also decreases with the water content, as a result of which the mildew of taro develops easily. Moreover, the addition of AMF makes it possible to minimize its propagation.

Abstract:The cultivation of taro is of great economic and social importance on a global scale. The current orientation towards agricultural production and the serious consequences of the mildew of taro to crops prompts to find alternatives to chemical control. This study aims at selecting in the taro habitat (leaves, rhizosphere) the microorganisms with high antagonistic potential capable of ensuring the biological control of P. colocasiae. Fungus isolated from the taro-infected leaves of the cultivar "Macumba or Ibo coco" from the V8-Agar medium, was kept in pure culture. The different antagonists were obtained by two trapping techniques using P. colocasiae as bait for the associated microorganisms and by the decimal dilution technique. The results reveal fourteen antagonist isolates, including five fungi and two bacteria isolated from the leaves; Against 4 bacteria and 3 fungi at ground level. Identification of the latter identified the presence of Penicillium Sp, Trichoderma Sp, Aspergillus Sp, Pythium Sp., Bacillus Sp, Rhizobium, Streptomyces and seven other unidentified isolates (Ni). The different in vitro tests showed that Rhizobium and Ni4 showed the strongest inhibitions (91.66 and 90.69%). The greenhouse tests showed the high-inhibitory effect of Trichoderma Sp. and Rhizobium, which showed very low foliar alteration percentages (9.65 and 1.86%). These antagonists would be of particular benefit to farmers in the development of biological pesticides.