Effects of the particle size of soil-less substrates upon AM fungus inoculum production

Production of inoculum of the arbuscular mycorrhizal fungus Glomus intraradices was examined in a locally available sand graded by particle size, planted with Zea mays and fertilized with a nutrient solution. Plants in sand with particle sizes of 0.50-0.78 mm had higher root fresh weights, spore production and percent mycorrhizal colonization than with other particle sizes. Production of spores and infectious propagules was enhanced by a nutrient solution without P. Plants were also inoculated with G. intraradices in pots containing clay-brick granules, charcoal, coalmarl, sand or perlite of the optimal particle size (0.50-0.78 mm). Percent root length colonized by G. intraradices and production of infectious propagules were 40-50% higher for plants grown in clay-brick granules and sand than in the other media.