Crop residue degradation by fungi isolated from conservation agriculture fields under rice–wheat system of North-West India

Purpose In North West-Indo Gangetic Plains (NW-IGP) ofIndia in situ burning of crop residues is practiced bymajority of farmers’ which deteriorates soil and environmentalquality. Fungi have the potential for lignocellulosedegradation and can be used for the in situ decompositionof crop residues. Lignocellulose degrading fungal spp.were isolated and evaluated for the activity of lignocellulolyticenzymes.Method The lignocellulose degrading fungi were isolatedby appearance of zone on carboxy methyl cellulose (CMC)agar media and tannic acid (TA) media. Carboxy methylcellulase, filter paperase, cellobiase, xylanase and laccaseactivity were estimated in submerged, as well as solid statefermentation using a mixture of rice and wheat straw in theratio of 4:1. rice–wheat straw as substrate. The residue leftafter solid state fermentation was evaluated for carbon/nitrogenratio, dry mass loss, and loss of cellulose, hemicelluloseand lignin. Selected potential isolates werefurther tested in pot experiment for their effect on wheatplants. The interaction among isolates was also studied.Result After primary screening, 19 out of a total of 72fungal isolates were selected based on their enzymaticactivity profile and potential to degrade lignocellulosicresidues in submerged fermentation. Out of these 19 isolates,11 were further selected based on their enzymaticsecretions in solid state fermentation. All the 11 strainswere identified morphologically. Four fungal isolates(RPW 1/3, RPW 1/6, RPWM 2/2 and RZWM 3/2) showedhigher enzymatic activities and more loss of dry mass andcell wall constituents over the other isolates. These isolateswere identified by ITS region sequencing as Aspergillusflavus, Aspergillus terreus, Penicillium pinophilum andAlternaria alternata.Conclusion This study revealed that fungal isolates may beused for managing crop residues in conservation agriculturebased rice–wheat system of NW-IGP to eliminate illeffects of residue burning.