Relation of Inoculation of Bradyrhizobium japonicum and Mycorrhizal Fungus with Root Colonization, Quantity and Quality of Soybean (Glycine max) Yield in Different Levels of Potassium

The effect of inoculation of Bradyrhizobium and mycorrhizal fungus on root colonization, yield quantity and quality of soybean (Glycine max) in different levels of potassium, Studied by field experimental in Shahrood University Agricultural Research Station during growing season of 2012. The experiment was a factorial experiment based on randomized complete blocks design (RCBD) with three replications. The factors included mycorrhizal inoculation (non-inoculated and inoculated with Glomus intraradices), nitrogen fixation bacteria inoculation included (non-inoculated and inoculated with Bradyrhizobium japonicum) and potassium fertilizer (0, 100 and 200 kg.ha-1). Results showed that mycorrhizal factor significantly affected all of studied traits except number of seeds per pod, number of pods per plant and grain yield.Mycorrhizal inoculation significantly increased pod dry weight, root colonization percent, protein percent, oil percent and biological yield. Bradyrhizobium inoculation factor significantly affected all of studied traits. The potassium fertilizer factor significantly affected all of studied traits except number of seeds per pod trait. In most cases between 100 kg.ha-1and 200 kg.ha-1of fertilizer was not significant difference. Dual inoculation of mycorrhizal and Bradyrhizobium bacteria interactions significantly affected number of pods per plant, oil percent and root colonization percent. Bradyrhizobium, mycorrhizal fungi and potassium interactions significantly affected all of studied traits except number of seeds per pod.