Effect of plant growth promoting rhizobia on seed germination and seedling traits in Acacia senegal

Among arid zone tree species, Acacia senegal and Prosopis cineraria are the most important dryland resources of Western Rajasthan desert ecosystem. Due to ecological, biological and molecular similarities, they are often studied together. The climatic conditions in this region restrict the build-up of soil organic matter and soils are generally deficient in nitrogen. Studies were carried out to isolate and molecularly characterize the diverse group of plant growth promoting rhizobacteria from root nodules of native A. senegal and P. cineraria and their effect on seed germination and seedling traits in two genotypes of A. senegal. The direct sequencing of 16S rDNA region resulted in molecular identification of plant growth promoting rhizobacteria as Bacillus licheniformis, Sinorhizobium saheli isolated from root nodules of A. senegal and S. kostiense and S. saheli isolated from root nodules of P. cineraria. The partial sequences of 16S rDNA were assigned Gen accession numbers HQ738496, HQ738499, HQ738506 and HQ738508. Scarification treatment with sulphuric acid (98%) for 15 minutes was able to break the exogenous seed dormancy and enhanced germination percentage in control treatment to 90% and 92.5% in A. senegal in genotypes CAZRI 11113AS and CAZRI 35AS, respectively. The treatments with Bacillus licheniformis or S. kostiense, either inoculated individually or as coinoculants, had positive effect on phenotypic traits of germination. Two A. senegal genotypes exhibited significant differences with regard to all the phenotypic traits. On the other hand, treatments with S. saheli isolated from either A. senegal or P. cineraria had negative effects on germination and related phenotypic traits. Values of the coeffivient of determination (R2) over 80% for root length versus shoot length, root/shoot ratio and seedling weight respectively validate that the observed attributes are inter-dependable and linear progression trend can be predicted.</span

Not Available

Not AvailableComparative microbial community structure analysis of agricultural soil located in hot, western Rajasthan with long term history of chemical pesticides vis-à-vis pristine soil has been attempted using the technique of PCR-RFLP. Pesticide contaminated (24 nos.) and pristine (10 nos.) soil samples were collected from different locations of the vegetable growing agricultural fields. Metagenomic DNA was extracted each from pooled-contaminated and pooled-pristine soils and amplified with universal 16S rRNA gene primers. Amplification products were cloned in to E. coli DH5α cells to obtain 78 and 39 16S rDNA clones from contaminated and pristine soils respectively. The clones were subjected to RFLP analysis using three restriction enzymes (AluI, AvaII and MspI) followed by phylogenetic tree construction. The studies revealed differences in microbial community structures of both types of arid, agricultural soils. We also detected the presence of pesticide-degrading naphthalene dioxygenase gene (nahA) controlling the initial step of the degradation process in contaminated soil.Not Availabl

Not Available

Not AvailableThe study carried out to isolate and evaluate efficient Rhizbium cultures from guar and moth bean plants grown at farmers’ fields in arid districts of western Rajasthan showed that the GBR-2 and GBK-21-2 cultures from guar and MBR-8 and MBK-15 from moth bean grew fast and developed wet and gummy colonies on YEMA plates within 24- 48 hrs. Cultures of GBR-2 and GBK-21-2 also exhibited better plant biomass in nursery and 15-18 per cent higher yield and nodulation over the uninoculated control under field conditions. MBR-8 and MBK-15 also exhibited higher plant biomass in nursery and higher yield (up to 19 %) and nodulation over the uninoculated control under field conditions. MBR-8 was used for studying the shelf life of the liquid bioformulations for later use as bioinoculant. The liquid bioformulations having polyethylene glycol (0.5%) or gum arabic (0.5%) as cell protectants or top layer of castor oil retained viable cell density (e” 1010 cfu ml-1) up to 180d after storage.Not Availabl

Not Available

Not AvailableComparative microbial community structure analysis of agricultural soil located in hot, western Rajasthan with long term history of chemical pesticides vis-à-vis pristine soil has been attempted using the technique of PCR-RFLP. Pesticide contaminated (24 nos.) and pristine (10 nos.) soil samples were collected from different locations of the vegetable growing agricultural fields. Metagenomic DNA was extracted each from pooled-contaminated and pooled-pristine soils and amplified with universal 16S rRNA gene primers. Amplification products were cloned in to E. coli DH5α cells to obtain 78 and 39 16S rDNA clones from contaminated and pristine soils respectively. The clones were subjected to RFLP analysis using three restriction enzymes (AluI, AvaII and MspI) followed by phylogenetic tree construction. The studies revealed differences in microbial community structures of both types of arid, agricultural soils. We also detected the presence of pesticide-degrading naphthalene dioxygenase gene (nahA) controlling the initial step of the degradation process in contaminated soil.Not Availabl

Not Available

Not AvailablePlant growth promoting rhizobacteria (PGPRs) from the rhizosphere and root nodules of native Acacia senegal (L.) Willd. and Prosopis cineraria (L.) Druce trees in Western Rajasthan were molecularly characterized by direct sequencing of the 16S rRNA gene. Of the nine isolates obtained from A. senegal, the lone rhizospheric isolate was identified as Stephyllococus hominis Kloos and Schleifer and the remaining eight from root nodules were characterised as Sinorhizobium saheli De Lajudie. Eight isolations from P. cineraria included Lysinibacillus sphaericus Meyer Neide and Bacillus subtilis (Ehrenberg) Cohn (one isolate each) from rhizosphere and Sinorhizobium kostiense Nick (one) and S. saheli (five) from root nodules. Eight RAPD primers detected intra-specific variations generating scorable amplicons and revealed 130 bands with 100% polymorphism. The phylogram based on multiple sequence alignment of 16S rRNA gene delineated not only different genera of PGPRs but also recognized four strains of S. saheli.Not Availabl

Not Available

Not AvailableAmong arid zone tree species, Acacia senegal and Prosopis cineraria are the most important dryland resources of Western Rajasthan desert ecosystem. Due to ecological, biological and molecular similarities, they are often studied together. The climatic conditions in this region restrict the build-up of soil organic matter and soils are generally deficient in nitrogen. Studies were carried out to isolate and molecularly characterize the diverse group of plant growth promoting rhizobacteria from root nodules of native A. senegal and P. cineraria and their effect on seed germination and seedling traits in two genotypes of A. senegal. The direct sequencing of 16S rDNA region resulted in molecular identification of plant growth promoting rhizobacteria as Bacillus licheniformis, Sinorhizobium saheli isolated from root nodules of A. senegal and S. kostiense and S. saheli isolated from root nodules of P. cineraria. The partial sequences of 16S rDNA were assigned Gen accession numbers HQ738496, HQ738499, HQ738506 and HQ738508. Scarification treatment with sulphuric acid (98%) for 15 minutes was able to break the exogenous seed dormancy and enhanced germination percentage in control treatment to 90% and 92.5% in A. senegal in genotypes CAZRI 113AS and CAZRI 35AS, respectively. The treatments with Bacillus licheniformis or S. kostiense, either inoculated individually or as coinoculants, had positive effect on phenotypic traits of germination. Two A. senegal genotypes exhibited significant differences with regard to all the phenotypic traits. On the other hand, treatments with S. saheli isolated from either A. senegal or P. cineraria had negative effects on germination and related phenotypic traits. Values of the coeffivient of determination (R2) over 80% for root length versus shoot length, root/shoot ratio and seedling weight respectively validate that the observed a- ttributes are inter-dependable and linear progression trend can be predicted.Not Availabl

Effect of plant growth promoting rhizobia on seed germination and seedling traits in Acacia senegal

Among arid zone tree species, Acacia senegal and Prosopis cineraria are the most important dryland resources of Western Rajasthan desert ecosystem. Due to ecological, biological and molecular similarities, they are often studied together. The climatic conditions in this region restrict the build-up of soil organic matter and soils are generally deficient in nitrogen. Studies were carried out to isolate and molecularly characterize the diverse group of plant growth promoting rhizobacteria from root nodules of native A. senegal and P. cineraria and their effect on seed germination and seedling traits in two genotypes of A. senegal. The direct sequencing of 16S rDNA region resulted in molecular identification of plant growth promoting rhizobacteria as Bacillus licheniformis, Sinorhizobium saheli isolated from root nodules of A. senegal and S. kostiense and S. saheli isolated from root nodules of P. cineraria. The partial sequences of 16S rDNA were assigned Gen accession numbers HQ738496, HQ738499, HQ738506 and HQ738508. Scarification treatment with sulphuric acid (98%) for 15 minutes was able to break the exogenous seed dormancy and enhanced germination percentage in control treatment to 90% and 92.5% in A. senegal in genotypes CAZRI 113AS and CAZRI 35AS, respectively. The treatments with Bacillus licheniformis or S. kostiense, either inoculated individually or as coinoculants, had positive effect on phenotypic traits of germination. Two A. senegal genotypes exhibited significant differences with regard to all the phenotypic traits. On the other hand, treatments with S. saheli isolated from either A. senegal or P. cineraria had negative effects on germination and related phenotypic traits. Values of the coeffivient of determination (R2) over 80% for root length versus shoot length, root/shoot ratio and seedling weight respectively validate that the observed attributes are inter-dependable and linear progression trend can be predicted

Not Available

Not AvailableNot AvailableNot Availabl

Not Available

Not AvailableNot AvailableNot Availabl

Not Available

Not AvailableClimatic models and predictions indicate increase in aridity world over due to global warming. Arid environments occupy about one third land area of the world. is the most important dryland resource of western Rajasthan desert ecosystem. The seeds of 13 low and high seed yielding exotic and indigenous provenances were evaluated for diversity and interrelationship among growth related seedling traits targeting establishment and end use of this species. Under the present study most of the growth related seedling traits varied within and amongst provenances. Highly significant correlation of dry biomass per plant of more than 72% with root length (73.3%), collar diameter (72.2%), shoot dry weight (99.7%), root dry weight (95.7%) and seedling length (79.9%) under the present study may be used for early selection. Similarly, highly significant positive correlation of seedling length with seven out of 12 growth related seedling traits validate strong inherent association of these traits under strong genetic control and are amenable for selection. Significant negative correlation in number of nodules per plant with root/shoot length ratio (-57.6%) and no correlation with 10 out of 12 growth related seedling traits tested advocate emphasis on other growth related seedling traits in selection of elite genotypes for afforestation. The non significant associations suggest that per cent germination was independent of other characters and could be selected separately.Not Availabl