Influence of crop combinations and soil factors on diversity and association of arbuscular mycorrhizal fungi in arecanut based cropping systems

<p>Arbuscular mycorrhizal (AM) species diversity and extent of association were investigated in arecanut based cropping systems<br />differing in crop combinations. The study was carried out in farmers’ fields under acidic soil conditions at three locations representing<br />low land (Maneikkara), midland (Cheruvanjeri) and high land (Nedumpoyil) regions of Kannur district in Kerala. The cropping<br />systems in Maneikkara, Cheruvanjeri and Nedumpoyil had arecanut-banana, arecanut-banana-black pepper and arecanut-bananablack<br />pepper-cardamom as component crops. AM spore load and root colonization differed significantly in arecanut in the three<br />cropping systems. Highest spore load was recorded in Maneikkara followed by that in Nedumpoyil and Cheruvanjeri regions.<br />Crops which formed components of the cropping system differed in root colonization levels, with banana recording the highest<br />level, followed by arecanut, black pepper and cardamom. Colonization pattern was Paris type in all crops, but varied with respect<br />to predominance of arbuscules in arecanut and vesicles in banana. Arecanut-black pepper-banana system at Cheruvanjeri in<br />midland was superior with respect to species diversity and species richness as evidenced by Shannon–Weiner index (Hs), Simpson’s<br />index of diversity (Ds) and species richness index. Arecanut-banana cropping system in Maneikkara in low land had low level of<br />species diversity and species richness, indicating the combined influence of crop combinations and soil factors such as N and P on<br />AM diversity and distribution. Rhizophagus fasciculatus, Funneliformis geosporum, F. mosseae, Glomus macrocarpum,<br />G. aggregatum, G. multicaule, G. glomerulatum and Acaulospora bireticulata were the AMF species identified from the arecanut<br />cropping systems. F. geosporum was the most abundant (29-50%) species in the cropping system. The relative occurrence and<br />abundance of AM species varied significantly with respect to the crops and locations.</p>