Root and plant characters in wheat under low input field conditions with dual inoculation of mycorrhiza andAzotobacter chroococcum: Gene effects

Abstract

Field experiments were conducted over two years under low input conditions to know the influence of bio-inoculants, namely arbuscular mycorrhiza fungi (AMF, Glomus fasciculatum) and Azotobacter chroococcum (Azc) on the performance and gene effects for important root and plant characters in three crosses of wheat (WH147×WH157, WH147×PBW175 and WH147×WH542). Six generations representing P1, P2, F1, F2, BC1 and BC2 populations of each cross were grown in randomized block design with three replications. The estimate of means (m) indicated that bio-inoculants enhanced the mean performance of most of the characters and root length density and grain yield in some crosses only. Crop season also showed considerable effect on impact of bio-inoculants. The joint scaling test revealed adequacy of additive-dominance model of gene effects for root biomass, root length density, flag leaf area, tillers/plant, grain weight and grain yield in all the crosses and bio-inoculants treatments in both years. The AMF treatment brought about changes in the magnitude and significance of additive component for root biomass, plant height, flag leaf area in all the three crosses. Both additive (d) and dominance (h) components were affected with respect to grain yield in WH147×WH157 and WH147×WH542. The dominant component was important for tillers/plant, grain yield, root length in control, as well as bio-inoculants treated populations of WH147×PBW175 but treatment of AMF and AMF+Azc reduced the magnitude of h and increased the magnitude of d. Digenic interactions were prominent for grains/spike in WH147×WH157. Magnitude of digenic interactions was higher under bio-inoculation. Simple pedigree and bulk pedigree methods are suggested to capitalize on adequate additive gene effects for developing bio-inoculants responsive wheat genotypes.