Effects of Glomus etunicatum and G. intraradices on leaf chlorophyll index of sorghum under micronutrient deficiency conditions in soil-less culture system

Beneficial effects of arbuscular mycorrhizal fungi (AMF) on plant growth have been widely reported. But there is a lack of information on the effect of this symbiosis in soil-less culture systems. Therefore، this experiment was aimed to investigate the effect of mycorrhizal symbiosis on leaf chlorophyll index of sorghum plants grown in perlite media under micronutrients deficiency conditions. The experiment was laid out in factorial randomized complete blocks design with three replications. In pots with sterile and washed perlite، sorghum plants (Sorghum bicolor L.) were inoculated with either Glomus etunicatum or G. intraradices، or left un-inoculated as control. Three levels of micronutrients (zero، half and full strength) in Rorison’s nutrient solution were applied to the pots during vegetative growth period. Results showed that plant fresh weight in non-mycorrhizal and plants inoculated with G. etunicatum and G. intraradices were 90، 14 and 11 gr/pot، respectively. Mycorrhizal root colonization for G. etunicatum and G. intraradices treated plants was 43 and 37%، respectively. Chlorophyll index was significantly lower in mycorrhizal than non-mycorrhizal plants، and it was markedly declined with decreasing micronutrients concentration in the nutrient solution. With increasing plants age and approaching the reproductive stage، chlorophyll index was significantly increased. According to the obtained results، reduction in growth of mycorrhizal plants in comparison with non-mycorrhizal plants seems to be due to decreased chlorophyll content and thus reduced photosynthetic power in the presence of mycorrhizal fungi. Further research is needed for more careful evaluation of the effect of symbiosis fungi on growth and yield of plants in the soil-less culture systems.