Diversity of Glomale Mycorrhizal Fungi in Maize/Sesbania Intercrops and Maize Monocrop Systems in Southern Malawi

Abstract

The study investigated diversity and frequency of occurrence of glomale (Arbuscular-or Vesicular Arbuscular-) mycorrhizal fungi on three farming systems in a drought prone and nitrogen deficiency site in southern Malawi. The farming systems comprised of two agroforestry systems of Sesbania sesban (L) Merr intercropped with maize and Sesbania macrantha E Phillips & Hutch. intercropped with maize and a maize monocrop systems without fertilizer, with nitrogen, phosphorus and a combination of nitrogen and phosphorus. Species diversity and species frequency of occurrence were examined in soil samples obtained in the dry and wet seasons. Twelve glomale mycorrhizal species were recorded, four species being in the genus Acaulospora, four in Glomus, two in Gigaspora and two in Scutellospora. Species diversity in the two agroforestry systems were not significantly (p £ 0.05) different but had lower species diversity than maize monocrop with only Sesbania macrantha intercropped with maize significantly (p £ 0.05) lower. Species diversity was significantly increased by the inorganic nitrogen fertilizer. Inorganic phosphorus fertilizer had no effect. The study shows that the occurrence and persistence of glomale species are influenced by agroforestry combinations, and that the spores of most species are tolerant to dry conditions. Only four species responded to fertilizer application with the occurrence of spores of some species high and some low. Management practices have great implication in the persistence of spore propagules of glomale species.

Effect of different plant densities on the diversity of arbuscular mycorrhizal fungi community in a long-term maize monocrop system

“…Maize monoculture has been estimated to contain up to 5-18 AMF species related with different agricultural practices (Oehl et al, 2004;Bhadalung et al, 2005;Jefwa et al, 2006). Hence, it is difficult to compare results using different methods for estimating AMF diversity.…”

Species composition of arbuscular mycorrhizal fungi differ in semi-natural and intensively managed pastures in an isolated oceanic island (Terceira, Azores)

“…Khanam et al (2006) also found a positive correlation between soil nutrients levels (N, K, OM) and spore numbers in agricultural crops in Bangladesh. Nevertheless, the opposite has been observed in relation to total AMF spore density, which supported the generalisation that inorganic fertilisers may have a deleterious effect on many glomeromycotan species (Jefwa et al 2006). Among soil nutrients, phosphorus is considered to reduce the composition and diversity of AMF communities as well as spore and mycelium densities in both temperate and tropical systems (Agwa and Al-Sodany 2003;Oehl et al 2004;Jansa et al 2005;Khanam et al 2006).…”

Mycorrhiazal association in relation to soil properties and plant species density in Sidama of Southern Ethiopia

“…In return, AMF supply nutrients such as phosphorus, nitrogen (N), calcium (Ca), copper (Cu), manganese (Mn), sulphur (S) and zinc (Zn) (Sieverding, 1991;Ortas, 2002). But when the soil is rich in necessary nutrients, plants may not waste more energy for the association with AMF and go for the cheapest source of energy, and individual plant species and plant communities in natural and farming systems affect the distribution and diversity of AMF species (Dalpe et al, 2000;Jefwa et al, 2006). Therefore, according to the previous investigators, AMF spore density, diversity and rates of root colonization are dependent on soil physicochemical properties (Mahmud et al, 1999) and plant species density and richness (Allsopp and Stock, 1992).…”