Biodiversity of arbuscular mycorrhizal fungi of pumpkins (Cucurbita spp.) under the influence of fertilizers in ferralitic soils of Cameroon and Benin

Abstract

In Africa, many people suffer from nutrient deficiencies and this enhances the need for yield increase of crops like pumpkins with good nutritional qualities, while safeguarding the environment. The aim of this study was to assess the composition and specific diversity of arbuscular mycorrhizal fungi (AMF) in the rhizosphere of pumpkins under two fertilizer application systems. The experiment was conducted with a completely randomized design with a split-plot of three factors: fertilizers, pumpkin varieties and experimental sites. Dried seeds of pumpkin were sown after field preparation and at flowering and fruiting, samples of soil and root fragments were collected from the rhizosphere. In the laboratory, roots were clarified and coloured before microscopic observations. Soil samples were used for the extraction of spores through humid filtering. Spore suspension was poured into a Petri dish and spores counted with the help of a stereo microscope. The spores of AMF were identified on the basis of morphological descriptions. Results show that chemical fertilizer (T2) significantly reduces (p < 0.001) the frequency and intensity of mycorrhization compared with control (T0) and fowl droppings (T1). The hierarchical classification shows two classes (R2 = 0.63): T0 and T1; and T2. Some 15 AMF species of four genera were isolated and identified. Of these, Glomus (57.97-85.65%) and Acaulospora (12.68-40.42%) were the most abundant with high density (1086 spores/100 g of soil). Glomus intraradices was absent in Benin and present in Cameroon. Diversity indices were higher in Cameroon than in Benin.