Effects of Two Species of Arbuscular Mycorrhizal Fungi on Leachates pH of Sorghum and Tomato in Vegetative Growth Period under Micronutrient Deficient Condition

Colonization of roots with arbuscular mycorrhizal fungi (AMF) often improves micronutrients uptake by most of the plants. Measurement of pH in mycorrhizae leachates is an evidence for acidification or alkalinization of rhizosphere and hyphosphere. Leachate pH is very important factor for assessment of micronutrient uptake by AMF. This experiment was laid out in factorial complete randomized block design with three replications. The first factor consists of arbuscular mycorrhizal fungi with Glomus etunicatum and Glomus intraradices species and control, the second factor was Rorison’s nutrient solution with zero, half and full strength of micronutrients, and the third factor was time of measurement of leachates pH that was include 45, 65 and 85 days after sowing. Tomato (Lycopersicon esculentum Miller) and sorghum (Sorghum bicolor L.) plants were grown in sterile perlite and were inoculated with either Glomus etunicatum or G. intraradices, while the control set was left un-inoculated. Rorison's nutrient solution with three levels of 0, half and full strength of micronutrients was applied to the pots during vegetative growth period. The pH of leachates Measured at 45, 65 and 85 days after sowing (DAS). Results show that, colonization of sorghum roots by G. etunicatum and G. intraradices fungi were 43 and 37%, respectively. On the contrary of sorghum plants, the mycorrhizal symbiosis was not observed in tomato plants. The pH of leachates was lower in mycorrhizal than non-mycorrhizal plants. G. intraradices were efficient than G. etunicatum in this respect. The reduction in leachate pH was induced at 0 levels of the micronutrients. 65 DAS, leachates had minimum amount of pH. In all of treatments, pH of leachates were higher than 7.6. It seems that, the main agent of this phenomenon is nitrate nutrition of plants, because nitrate is the most source of N in Rorison’s nutrient solution.