Biological nitrogen fixation, mycorrhizal infection and Azolla symbiosis in two rice cultivars in Egypt

ABSTRACT

In this study, the effect of biofertilizers i.e. Azolla pinnata, arbuscular mycorrhizal fungi [AMF] and Azospirillum brasilense [Az] on the growth, grain yield, biological nitrogen fixation [BNF] and nutrient uptake by rice cultivars [Oryza sativa var. Giza 172, IR 28] was examined. The grains produced from the inoculated treatments were more than that from the uninoculated control. Similar trends were observed with N, P and K uptake by both rice cultivars. The inoculation treatments reflected that Azolla and its combinations had less N derived from fertilizer [Ndff] and higher N derived from air [Ndfa], while Azospirillum or AMF had higher Ndff and less Ndfa. 15N recovery percentages confirmed that AMF was the most effective inoculum for enhancing soil and/or fertilizer N uptake by rice cultivars, while Azolla was considered a suitable agent for transferring fixed N to rice plants