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  • Author or Editor: N. Narula x
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A field experiment was carried out to investigate the establishment of phosphate-dissolving strains of Azotobacter chroococcum, including soil isolates (wild type) and their mutants, in the rhizosphere and their effect on the growth attributes and root biomass of three genetically divergent wheat cultivars (Triticum aestivum L.). Four fertilizer doses were applied: 90 kg N ha—1, 90 kg N + 60 kg P2O5ha—1, 120 kg N ha—1and 120 kg N + 60 kg P2O5ha—1, besides a control plot without fertilizers or bioinoculants. Phosphate-solubilizing and phytohormone-producing parent soil isolates and mutant strains of A. chroococcum were isolated and selected following the enrichment method. On an overall basis the mutant strains performed better than the soil isolates for in vitro phosphate solubilization (11–14%) and growth hormone production (11.35%). Seed inoculation of wheat varieties with phosphate-solubilizing and phytohormone-producing A. chroococcum showed a better response over the control. Mutant strains of A. chroococcum showed a higher increase in grain (15.30%) and straw (15.10%) yield over the control and better survival (12–14%) in the rhizosphere as compared to their parent soil isolate (P4). Mutant strain M15 performed better in all three varieties in terms of increase in grain yield (20.8%) and root biomass (20.6%) over the control.

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The present investigation was conducted to investigate the impact of bio-inoculants on the magnitude and direction of gene effects and mean performance for root length density, root biomass per plant, AMF colonization in roots and micronutrient uptake (Cu, Fe, Mn, Zn) in wheat under low input field conditions. The material for study comprised three wheat cultivars, WH 147 (low mineral input), WH 533 (drought-tolerant), Raj 3077 (high mineral input) and six generations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 ) of three crosses, namely WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077. The experiment was conducted in a randomized block design with three replications having three treatments, i.e. (i) control; (ii) inoculation with arbuscular mycorrhizal fungi (AMF, Glomus fasciculatum ); (iii) dual inoculation with AMF and Azotobacter chroococcum ( Azc ). The fertilizer doses in all three treatments were 80 kg N + 40 kg P + 18 kg ZnSO 4 ha −1 . Root length density, root biomass per plant, AMF colonization in roots and Zn and Mn content were found to be maximum after dual inoculation with AMF+ Azc in all three crosses. Joint scaling tests revealed that additive-dominance gene effects were mainly operative in governing the expression of root biomass, Cu and Zn content in all three crosses for all three treatments (i.e. control, AMF and AMF + Azc ). Pedigree selection in crosses WH 147 × WH 533 and WH 147 × Raj 3077 could be effective for breeding pure lines of wheat for sustainable agriculture (low input genotypes responsive to biofertilizers such as AMF and Azotobacter ).

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The present investigation was conducted to study the impact of bio-inoculants under low input field conditions on the magnitude and direction of gene effects and the mean performance of nitrogen (N) and phosphorus (P) use in wheat. Three wheat cultivars suitable for different agro-ecological conditions, i.e. WH 147 (low mineral input), WH 533 (water deficit), Raj 3077 (high mineral input), and six generations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 ) of three crosses, namely WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077, were evaluated in a randomized block design with three replications under low input field conditions (80 kg N + 40 kg P + 18 kg ZnSO 4 doses applied in each treatment) with three treatments, i.e. control, inoculation with arbuscular mycorrhiza fungi (AMF, Glomus fasciculatum ) and dual inoculation with AMF and Azotobacter chroococcum ( Azc ). Bioinoculation with AMF and AMF+ Azc had a positive impact on the mean performance of all the wheat crosses. The mean performance of AMF was maximum in the cross WH 147 × WH 533 for N and P response (%), N and P use index (%) and P content (ppm), whereas for N and P uptake it was maximum in the cross WH 147 × Raj 3077. The response and use index for N and P were better in the combined AMF+ Azc treatment in all three crosses. The adequacy of the additive-dominance model for the phosphorus uptake (mg/plant) by all three crosses in all three treatments (i.e. control, AMF, AMF+ Azc ) suggested that additive (d) and dominance (h) gene effects mainly governed the inheritance of this trait. In all cases, digenic interactions were present, where the duplicate type of epistasis prevailed except for the P content in the control in the cross WH 147 × WH 533, where the complementary type of interaction was present. Pedigree selection in crosses WH 147 × WH 533 and WH 147 × Raj 3077 could be effective for breeding pure lines of wheat for sustainable agriculture (low input genotypes responsive to biofertilizers such as AMF and Azotobacter ).

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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 P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 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.

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Abstract

In this study, we have studied the stability of TiO2–CdSe nanocomposites in which the individual moieties are linked using a bifunctional linker (mercaptopropionic acid). Nanoparticles of TiO2 and CdSe are synthesized by sol–gel and one pot methods. The equimolar amount of the above particles is utilized to prepare nanocomposites with and without linker. These samples are characterized for their structural, thermal, and optical properties using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infra-red spectroscopy (FTIR), and UV–Vis spectroscopy. The average particle size of TiO2 and CdSe are 16 and 23 nm, respectively. The addition of a bifunctional linker shows remarkable effect on the properties of TiO2–CdSe nanocomposites.

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