FIFTY PERCENT REPLACEMENT OF NITROGEN COMPOAST RECOMMENDATION FOR RICE BY A BIOFILM OF A DIAZOTRPH AND A RHIZOSPHERE FUNGUS

Author (s) : Dr. K. REVATHI, Mrs. K. GOMATHI & Ms. S. SHENBAGAVALLI

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Abstract :
A biofilm was formed between the diazotroph Azorhizobium caulinodans and rice rhizosphere fungi Aspergillus spp. and was named Azorhizobium-Aspergillus biofilm (AAB). AAB colonizes rice roots and colonization is enhanced in the presence of flavonoid naringenin (AAB/Nar). This study investigates the percentage of recommended urea fertilizer levels that can be replaced by the developed biofilm (AAB) and naringenin combination. A pot experiment of rice with the treatments 100% 15N labelled Urea recommendation with no AAB/Nar (Control), 75% of 15N urea recommendation + AAB/Nar combination (75% U AAB/Nar), 50% UAAB/Nar, and 25%UAAB/Nar was conducted for evaluating rice root colonization, nitrogen fixation (NFIX) and nitrogen yield (NYIELD) in 60 and 105 day old rice plants. A. caulinodans was labelled with a green fluorescent protein for in-vivo detection and the bacterial colonization was determined through green fluorescence intensities (Zen light, Zen 2012 software) & analysed by SAS version 9. 15N isotopic analysis of the pooled shoot and grain samples was done at University of California Davis, Stable Isotopic laboratory. The 60 day old plants showed the highest root colonization, shoot NYIELD and NFIX in treatment 50%UAAB/Nar. Plants treated with 50%UAAB/Nar and harvested on 105 days had the highest grain yield, NYIELD and NFIX. It can be concluded that 50% of the urea recommendation can be replaced by the developed biofilm/Naringenin combination, to obtain even a higher rice yield than that of 100% urea recommendation.

Keywords : Nitrogen fixation, Biofilm, Rice, 15N labelling, Azorhizobium caulinodans

Conference Date : 17/09/2021

Pages : 194

Paper ID : IESMDT192