Spore Abundance and Morphology of Arbuscular Mycorrhizal Fungi under Conservation Agriculture

Abstract

Soil is full of microbial diversity and microbes present in soil interact diversely with other living form present in soil e.g., soil microbes and plants. These interactions range from symbiosis to parasitic. Among these, the most predominating mutualistic symbiotic relation is mycorrhiza (associated with ∼80% of terrestrial plant species), formed between arbuscular mycorrhizal (AM) fungi and vascular plants. An experiment was conducted under three cropping system rice-maize-cowpea (RMCp), rice-wheat-green gram (RWGg) and rice-cauliflower-bororice cropping (RCfBr) to study influence of three different tillage intensities i.e., CT (conventional tillage), RT (reduced tillage), and ZT (zero tillage) with five different levels of fertilizer and residue application, R1 (0%Residue & 100%RDF), R2(100%Residue & 50%RDF), R3 (100%Residue & 75%RDF), R4 (50%Residue & 100%RDF), R5 (50%Residue & 75%RDF), on AMF spore load and diversity.The experimental design followed was split plot with tillage was main plot treatment and residue as sub plot treatment.  Result showed that AMF spores and diversity are significantly influenced of degree of soil disturbance under different tillage practices and cropping system in practice, however residue application imparted non-significant influence on AMF spore load and diversity. A significant lower spore count was observed under CT as degree of soil disturbance is excessive high under CT compared to RT and ZT. With respect to spore diversity, round (shape), brown (color) and free spores were predominating spore type. In reference to spore shape abundance sequence was round>spherical> oval while for spore color it was brown>yellow>hyaline and >90 % spore was free while attached spores were <5%. In case of AMF spore count influence of cropping system was more prominent compared to other factors (i.e., tillage and residue). In RMCp and RWGg, significant increase inspore count was observed compared to RCfBr cropping system. On second year of experimentation, in RCfBr cropping system a significant decline in spore number was detected due to inclusion of cauliflower which act as non-host of AMF.  Hence to attain benefits associated with AMF to arable crop we must reduce level of soil disturbance and avoid crucifer crops in cropping system.