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Aim of the present study was to develop effective indigenous plant growth promoting (PGP) rhizobacteria consortia for enhanced plant growth attributes and nutrient acquisition by wheat crop under g...

Plant beneficial rhizobacteria (PBR) is a group of naturally occurring rhizospheric microbes that enhance nutrient availability and induce biotic and abiotic stress tolerance through a wide array of mechanisms to enhance agricultural sustainability. Application of PBR has the potential to reduce worldwide requirement of agricultural chemicals and improve agro-ecological sustainability. The PBR exert their beneficial effects in three major ways; (1) fix atmospheric nitrogen and synthesize specific compounds to promote plant growth, (2) solubilize essential mineral nutrients in soils for plant uptake, and (3) produce antimicrobial substances and induce systemic resistance in host plants to protect them from biotic and abiotic stresses. Application of PBR as suitable inoculants appears to be a viable alternative technology to synthetic fertilizers and pesticides. Furthermore, PBR enhance nutrient and water use efficiency, influence dynamics of mineral recycling, and tolerance of plants to other environmental stresses by improving health of soils. This report provides comprehensive reviews and discusses beneficial effects of PBR on plant and soil health. Considering their multitude of functions to improve plant and soil health, we propose to call the plant growth-promoting bacteria (PGPR) as PBR.

The ability of a few soil bacteria to transform unavailable forms of phosphorus (P) and potassium (K) to an available form is an important feature in plant growth-promoting bacteria for increasing crop yields of high- P and K-demand crops. In this research, screening and characterization of thirty-five K-solubilizing bacterial (KSB) and P-solubilizing bacteria (PSB) isolate which were evaluated for their ability to solubilize K and P from the waste muscovite (WM), waste biotite (WB), tri-calcium phosphate (TCP) and rock phosphate (RP) by analyzing the soluble P and K content after 7, 14, 21 days after incubation (DAI) at 28±2 °C on MABs (Modified Aleksandrov Broths) and Pikovskaya's medium. The soluble P and K contents in all isolates were significantly (p

The aim of this work was to evaluate the effects of co-inoculation with phosphate-solubilizing and nitrogen-fixing rhizobacteria on growth promotion, yield, and nutrient uptake by wheat. Out of twenty-five bacteria isolated from the rhizosphere soils of cereal, vegetable, and agro-forestry plants in eastern Uttar Pradesh, three superior most plant growth-promoting (PGP) isolates were characterized as Serratia marcescens, Microbacterium arborescens, and Enterobacter sp. based on their biochemical and 16S rDNA gene sequencing data and selected them for evaluating their PGP effects on growth and yield of wheat. Among them, Enterobacter sp. and M. arborescens fixed significantly higher amounts (9.32 ± 0.57 and 8.89 ± 0.58 mg Ng−1 carbon oxidized, respectively) of atmospheric nitrogen and produced higher amounts (27.06 ± 1.70 and 26.82 ± 1.63 TP 100 µg mL−1, respectively) of IAA in vitro compared to S. marcescens (8.32 ± 0.39 mg Ng−1 carbon oxidized and 21.29 ± 0.99 TP 100 µg mL−1). Although both M. arborescens and S. marcescens solubilized remarkable amounts of phosphate from tricalcium phosphate likely through production of organic acids, however, Enterobacter sp. was inactive. The effects of these three rhizobacteria were evaluated on wheat in alluvial soils of the Indo-Gangetic Plain by inoculation of plants with bacterial isolates either alone or in combinations in both pot and field conditions for two successive years. Rhizobacterial inoculation either alone or in consortium of varying combinations significantly (P ≤ 0.05) increased growth and yield of wheat compared to mock inoculated controls. A consortium of two or three rhizobacterial isolates also significantly increased plant height, straw yield, grain yield, and test weight of wheat in both pot and field trials compared to single application of any of these isolates. Among the rhizobacterial treatment, co-inoculation of three rhizobacteria (Enterobacter, M. arborescens and S. marcescens) performed best in promotion of growth, yield, and nutrient (N, P, Cu, Zn, Mn, and Fe) uptake by wheat. Taken together, our results suggest that co-inoculation of Enterobacter with S. marcescens and M. arborescens could be used for preparation of an effective formulation of PGP consortium for eco-friendly and sustainable production of wheat.

The aim of the present investigation was to evaluate the mineral release abilities of ten rhizobacterial strains isolated from rhizosphere of various crops growing in the Indo-Gangetic Plain (IGP) of India. Their abilities to solubilize inorganic phosphorus (P) and potassium (K) minerals from insoluble tricalcium phosphate (TCP) and waste muscovite (WM) revealed that rhizobacteria significantly solubilized different levels of inorganic P and fixed K, respectively. Some of the rhizobacterial stains have the ability to produce ammonia, indole-3-acetic acid (IAA), and hydrogen cyanide (HCN). The identification based on the 16S rDNA gene sequencing of selected mineral-solubilizing rhizobacteria (MSR) having greater potential to serve as bioagents were identified as Bacillus subtilis (BRHU01, BRHU03, and BHU20), Bacillus tequilensis (BRHU02), Bacillus licheniformis (BRHU04), Bacillus pumilus (BRHU05), Bacillus flexus (BHU02), Brevibacillus formosus (BHU16), Bacillus methylotrophicus (BHU29), and Bacill...

The present investigation comprises a total of fifty potassium solubilizing bacterial (KSB) strains which were isolated from Oryza sativa, Musa paradisiaca, Zea mays, Sorghum bicolor and Triticum aestivum L. These strains were evaluated for their ability to solubilize the fixed K from waste biotite (WB). On the basis of K-solublization, the seven most efficient KSB strains were evaluated for K-solublizing dynamics from the WB at 7, 14 and 21 DAI (days after incubation) on MAMs (Modified Solid Aleksandrov Medium). Further, these screened seven KSB strains were used for their morphological, physiological and molecular chacterization. The KSB strains Bacillus licheniformis BHU18 and Pseudomonas azotoformans BHU21 showed significantly higher K-solublization 7.22 and 6.03 µg mL −1 at 30 °C and pH 7.0, respectively. A significantely higher zone of solubilization significantly higher was recorded with Pseudomonas azotoformans BHU21 (3.61 cm). Bacillus licheniformis BHU18 produced significantly higher (~23 µg mL −1 ) concentrations of indole-3-acetic acid. The diversity of KSB as bioinoculants to release potassium provides a win-win situation. Therefore, it is crucial to adopt efficient KSB strain interventions for the judicious use of chemical and biological resources for maximizing food production while reducing pollution and rejuvenating degraded land for agricultural benefit.

Injudicious application of chemical fertilizers in India has a considerable negative impact on economy and environmental sustainability. There is a growing need to turn back to nature or sustainable agents that promote evergreen agriculture. Among such natural bio-agents, the potassium solubilizing rhizobacteria (KSR), which solubilize fixed forms of potassium (K) to plant available K by various mechanisms including acidolysis, chelation, exchange reactions, complexolysis, and production of organic acids are considered one such available viable alternative. KSR represent an enormous potential to transform the problems associated with the agrarian sector. Twelve KSR were isolated from rhizosphere of common Kharif crops (maize, banana, sugarcane, potato, pigeon pea, and tobacco) based on their ability to solubilize waste mica (muscovite and biotite) in plate assay. All these KSR were capable of K-solubilization from waste mica in both solid and liquid medium in-vitro. On the basis of 16S ribosomal DNA (16S rDNA) sequencing, out of 12 KSR, 7 strains belonged to Agrobacterium tumefaciens species, 2 strains each representing Rhizobium pusense and Flavobacterium anhuiense clade, while one strain showed affiliation to Rhizobium rosettiformans. As a result, among the assessed 12 KSR, A. tumefaciens OPVS 11 and R. pusense OPVS6 occurred at the highest K-solubilizing frequency. Studies on mechanism of K-solubilization by these strains demonstrated significant reduction in media pH and increased K release with incubation period under both waste muscovite and biotite as a sole source of insoluble K mineral.

Effect of concentrate organic manure (wellgrow grain and wellgrow soil) and NPK improved the growth and yield of wheat. Significant improvement in terms of growth parameters like plant height, tillers, dry matter production and productive tillers with application of 120 : 60 : 60 NPK + 300 kg wellgrow soil/ha and at par with application of 120 : 60 : 60 NPK + 300 kg wellgrow grain/ha, treatment receiving 100% NPK + 300 kg wellgrow soil/ha resulted maximum grain yield (4545 kg /ha). Treatment of 100% NPK + 300 kg wellgrow grain/ha maintained higher straw yield (5715 kg/ha) and test weight (44.10 g) due to application of 100 % NPK along with 200 kg wellgrow soil/ha whereas it was at par with application of 75 and 100% NPK with both levels of wellgrow formulation. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22738 Bangladesh J. Bot. 44(1): 143-146, 2015 (March)

The aim of this research work is to evaluate the potentiality of bacterial strains isolated from rhizosphere of various cropping systems on growth, yield and soil microbial populations at harvest of wheat under pot and field experiments. Bacterial isolates, isolated from rhizosphere of various cropping systems. Morphological, biochemical and molecular characterization of bacterial strains were done. All the bacterial strains were rod shaped and ammonia producers. Most of the strains were Gram’s +ve and showed positive to catalase, VP, MR tests and HCN production. Pseudomonas aeuroginosa showed significantly lowest pH 4.42 of broth and solubilized 160.34 µgml-1 tri-calcium phosphates. Enterobacter sp. produced maximum 27.06 µgml-1 IAA at 100 µgml-1 tryptophan. All the bacterial strains showed >97% similarity with strains already submitted to NCBI Gene bank. Arthrobacter chlorophenolicus and Enterobacter sp. showed maximum and significantly 23.60 and 28.97% plant height in pot and field experiments at 90 days after sowing. Bacillus megaterium caused maximum and significantly 51.45 and 40.47% grain and straw yield, respectively under pot while Serratia marcescens showed 14.78 and 17.04% grain and straw yield in field as compared to control. Most of the strains showed significant effect on microbial populations of post harvest soil under pot and field. It was concluded that A. chlorophenolicus, Enterobacter sp., B. megaterium and S. marcescens are effective strains of plant growth promoting bacterial strains for wheat crop production under Indo- Gangetic plains of India. Key words: Bacterial strains, biochemical, growth, microbial population, wheat, yield.

In soil system, 90%-98% K reserves are non-exchangeable mineral sources and potassium solubilizing microbes (KSMs) can effectively dissolve this mineral. Nowadays focused research on efficient KSMs was started. These microbes are able to enhanced their root colonization and improve plant growth and development. They solubilize K-minerals through different mechanisms including chelation, acidolysis, lowering of pH, exchange reaction, complexation, biofilm formation and secretion of organic acid and polysaccharides. Bio-priming of seed/root through efficient KSMs resulted higher crop productivity, potassium use efficiency (KUE) and mitigate the K-deficiency in soils. In this article we are trying to summarize the KSMs current state of knowledge in agricultural crops. We highlighted the knowledge gaps and suggest future prospective of research, with hope that the use of KSMs in agricultural soil improved soil sustainability.

The aims of our study were to enhance growth, yield and micronutrient status of wheat crop by various combinations of microbial strains (Bacillus megaterium, Arthrobacter chlorophenolicus and Enterobacter sp.) under pot and field experiments. Microbial strains were isolated from soils of different cropping systems and characterized by biochemical and molecular methods. Microbial strains (B. megaterium BHU1 and A. chlorophenolicus BHU3) showed positive result for nitrogen fixation and phosphate solubilization, while Enterobacter sp. BHU5 gave positive result in nitrogen fixation only. However, A. chlorophenolicus and Enterobacter sp. showed HCN production while B. megaterium and Enterobacter sp. gave siderophore. Maximum N2-fixation and IAA production were observed with 15.0 mg N g−1 carbon by A. chlorophenolicus and 26.4 µg ml−1 at tryptophan 100 µg ml−1 by Enterobacter sp, respectively. Triple combination of strains B. megaterium, A. chlorophenolicus and Enterobacter significantly increased 17.5%, 79.8%, 78.6% and 26.7% plant height, grain yield, straw yield and test weight under pot condition and also 29.4%, 27.5%, 29.5% and 17.6% under field condition, respectively. Similarly these treatment combinations showed maximum nutrient acquisition and content of micronutrient viz. Fe, Cu, Mn and Zn in grain of wheat under both conditions. The results showed that the combined application of indigenous PGPR, B. megaterium, A. chlorophenolicus and Enterobacter can be used as efficient microbial consortium for wheat production.

The potassium solubilizing microorganisms (KSMs) are a rhizospheric microorganism which solubilizes the insoluble potassium (K) to soluble forms of K for plant growth and yield. K-solubilization is carried out by a large number of saprophytic bacteria (Bacillus mucilaginosus, Bacillus edaphicus, Bacillus circulans, Acidothiobacillus ferrooxidans, Paenibacillus spp.) and fungal strains (Aspergillus spp. and Aspergillus terreus). Major amounts of K containing minerals (muscovite, orthoclase, biotite, feldspar, illite, mica) are present in the soil as a fixed form which is not directly taken up by the plant. Nowadays most of the farmers use injudicious application of chemical fertilizers for achieving maximum productivity. However, the KSMs are most important microorganisms for solubilizing of fixed form of K in soil system. The KSMs are an indigenous rhizospheric microorganism which shows effective interaction between soil and plant systems. The main mechanism of KSMs is acidolysis, chelation, exchange reactions, complexolysis and production of organic acid. According to literature, currently negligible use of potassium fertilizer as a chemical form has been recorded in agriculture for enhancing crop yield. Most of the farmers use only nitrogen and phosphorus and not use the K fertilizer due to unawareness so that the problem of K deficiency occurs in rhizospheric soils. The K fertilizer is also costly as compared to other chemical fertilizers. Therefore, the efficient KSMs should be applied for solubilization of a fixed form of K to an available form of K in the soils. This available K can be easily taken up by the plant for growth and development. Our aim of this review is to elaborate on the studies of indigenous K-solubilizing microbes to develop efficient microbial consortia for solubilization of K in soil which enhances the plant growth and yield of crops. This review highlights the future need for research on potassium (K) in agriculture.

A field experiment was conducted during rabi season, 2009-2010 at Agricultural Research Farm, BHU, Varanasi, on alluvial soils to determine the effects of concentrate organic manure (wellgrow formulations) with levels of inorganic fertilizers. The results reveal that the higher soil microbial population was seen with the application of 100% NPK + 300 kg wellgrow soil ha-1. Soil enzymes varied with the production systems. The urease, phosphatase and dehydrogenase activities were higher in wellgrow dose application with recommended dose of NPK. The soil enzymes and microbial population (bacteria, fungi and actinomycetes) were very responsive to organic manure application, but their levels and activities were not reflected in wheat crop under alluvial soils. Enzymatic activities were positively and significantly correlated with content of organic carbon. Key words: Dehydrogenase, phosphatase, urease, bacteria, fungi, actinomycetes, wellgrow.

Potassium (K) is needed in adequate quantities for a crop to achieve its maximum yield. The function of potassium in plant growth has not been clearly defined but it is associated with movement of water, nutrients and carbohydrates in plant tissue. When potassium is not adequate, the plants will have poor root development and will grow slowly, and their seeds will become small and have lower yields. About 5 million tonnes of potassic fertilizer requirement would be fulfilled through imports because India does not have commercial-grade sources of potash reserve. India is totally dependent on the import of potassic fertilizers. On the other hand, India has the largest reserve for low potassium-containing minerals. The depletion of potassium in soil has been started, and in future this will aggravate. In most of the soils, about 90–98 % of total K exists in relatively unavailable minerals such as feldspar, orthoclase and the micas (muscovite, biotite, phlogopite, etc.). These minerals are very resistant to decomposition and probably supply relatively smaller quantity of potassium to growing crops. Potassium in soil is present in four forms: water-soluble (solution K), exchangeable, non-exchangeable and structural or mineral forms. The fixed form of K minerals is solubilized by K solubilizers, and then acquisition or accumulation of potassium by crop plants certainly will be enhanced. For evergreen agriculture, production can only be fulfilled when the environment, its caretakers and surrounding communities are healthy, for this application of KSMs holds a key approach for K availability in soils. KSB increased K availability in soils and increased mineral nutrient specially K uptake by plant.

The nutrients are one of the basic inputs for achieving increased crop productivity, and potassium is one of them. In a recently published nutrient budget, it has been shown that potassium became unbalanced through increased removal and increased system leakage, simplification (monoculture) and increased demand for rapid plant growth. Addressing this nutrient imbalance and shortages in developing countries, it would be required to enhance the world production of potassium fertiliser. India is not self-sufficient in producing potassium fertiliser. The entire quantities of potassium fertilisers are imported. Therefore efficient management in soil fertility is a prime concern to the scientist in view of the increasing gap between production and consumption of fertiliser with time. So, nowadays, crop nutrient stability is important to mitigate the exhaustion of soil nutrient stock for sustaining the crop yield and to reinstate the soil fertility. In these circumstances, it is suitable to study the present knowledge of substitutive sources of K. So this assessment imparts an opportunity to flourish native mineral sources of K as a substitute to impede costly remunerative fertilisers. So, bio-intrusion of potassium minerals with potassium-solubilising microorganism (KSM) would be a preferable and feasible technology to solubilise unavailable form of K minerals into available pool for plant uptake and efficiently used as a source of K fertiliser for maintaining the ecological balance and sustaining agricultural production and environmental quality.

One major challenge for the twenty-first century will be the production of sufficient food for the global human population. The negative impacts on soil–plant–microbes–environmental sustainability due to injudicious use of chemical fertilizer, pesticide, insecticide, etc. by the unaware farmers deteriorate soil and environment quality. One possible way to use efficient soil microorganisms to remediate nutrient deficiency in agricultural soils and other plant growth-promoting (PGP) activities that can be of help for plant growth and development. The Bacillus species is one the most dominant rhizospheric bacterial/rhizobacteria species like Bacillus subtilis, B. cereus, B. thuringiensis, B. pumilus, B. megaterium, etc. that can help enhance the plant growth and development by different mechanisms, which PGPR can inhibit phytopathogens is the production of hydrogen cyanide (HCN) and/or fungal cell wall degrading enzymes, e.g., chitinase and s-1,3-glucanase. Direct plant growth promotion includes symbiotic and non-symbiotic PGPR which function through production of plant hormones such as auxins, cytokinins, gibberellins, ethylene, and abscisic acid. Mitigate the challenge by adopting eco-friendly crop production practices. Some Bacillus species function as a sink for 1-aminocyclopropane-1-carboxylate (ACC), the immediate precursor of ethylene in higher plants, by hydrolyzing it into α-ketobutyrate and ammonia and in this way promote root growth by lowering indigenous ethylene levels in the micro-rhizo environment. Bacillus species also help in solubilization of mineral phosphates, potassium, zinc, and other nutrients; rhizobacteria retain more soil organic N and other nutrients in the soil–plant system, thus reducing the need for fertilizers and enhancing release of the nutrients from indigenous or mineral sources, enhancing the economic and environmental sustainability.

Increasing cost of the fertilizers with lesser nutrient use efficiency necessitates alternate means to fertilizers. Soil is a storehouse of nutrients and energy for living organisms under the soil-plant-microorganism system. These rhizospheric microorganisms are crucial components of sustainable agricultural ecosystems. They are involved in sustaining soil as well as crop productivity under organic matter decomposition, nutrient transformations, and biological nutrient cycling. The rhizospheric microorganisms regulate the nutrient flow in the soil through assimilating nutrients, producing biomass, and converting organically bound forms of nutrients. Soil microorganisms play a significant role in a number of chemical transformations of soils and thus, influence the availability of macro- and micronutrients. Use of plant growth-promoting microorganisms (PGPMs) helps in increasing yields in addition to conventional plant protection. The most important PGPMs are Azospirillum, Azotobacter, Bacillus subtilis, B. mucilaginosus, B. edaphicus, B. circulans, Paenibacillus spp., Acidithiobacillus ferrooxidans, Pseudomonas, Burkholderia, potassium, phosphorous, zinc-solubilizing microorganisms, or SMART microbes; these are eco-friendly and environmentally safe. The rhizosphere is the important area of soil influenced by plant roots. It is composed of huge microbial populations that are somehow different from the rest of the soil population, generally denominated as the “rhizosphere effect.” The rhizosphere is the small region of soil that is immediately near to the root surface and also affected by root exudates.

The potassium solubilizing microorganisms (KSMs) are a rhizospheric microorganism which solubilizes the insoluble potassium (K) to soluble forms of K for plant growth and yield. K-solubilization is carried out by a large number of saprophytic bacteria (Bacillus mucilaginosus, B. edaphicus, B. circulans, Acidothiobacillus ferrooxidans, Paenibacillus spp.) and fungal strains (Aspergillus spp. and Aspergillus terreus). Major amounts of K containing minerals (muscovite, orthoclase, biotite, feldspar, illite, mica) are present in the soil as a fixed form which is not directly taken up by the plant. Nowadays most of the farmers use injudicious application of chemical fertilizers for achieving maximum productivity. However, the KSMs are most important microorganisms for solubilizing fixed form of K in soil system. The KSMs are an indigenous rhizospheric microorganism which show effective interaction between soil-plant systems. The main mechanism of KSMs is acidolysis, chelation, exchange reactions, complexolysis and production of organic acid. According to the literature, currently negligible use of potassium fertilizer as chemical form has been recorded in agriculture for enhancing crop yield. Most of the farmers use only nitrogen and phosphorus and not the K fertilizer due to unawareness that the problem of K deficiency occurs in rhizospheric soils. The K fertilizer is also costly as compared to other chemical fertilizers

Major part of potassium in soil exists in form of insoluble K-minerals. Fraction of Ksolubilized from such minerals through potassium solubilizing bacteria (KSB) will reduce cost on import of K- fertilizers. Nine and four isolates of K-solubilizing bacteria from Inceptisol (KI) and Alfisol (KA), respectively were evaluated for their ability to release of K from waste mica at 7, 14 and 21 days of incubation in modified Aleksandrov medium containing powdered waste mica as sole source of potassium. Morphological characteristics, zone of solubilization at week end and acidity of broth at different incubation periods were also studied. Majority of the isolates were entire smooth margin, raised, translucent, gram +ve rods and whitish to creamy in appearance. Isolates from cereals caused more zone of solubilization than pulse isolates. Isolates either from Alfisol or from Inceptisol efficiently decreased pH of the broth with increase in incubation periods. Isolates of same soil type differed in their K-release capacity. KSB isolates from Inceptisol showed higher K solubilization potential than isolates from Alfisol. Isolate KI1 & KA19 caused maximum acidity but lowest release of K from mica indicated that decrease in pH of the medium is not the only mechanism of K release from native K mineral of soil. Isolate KI16 and KA59 were high slime producer and showed highest 23.88 and 13.71 μg mL−1 K solubilization capacity, respectively and emerged out as potential isolates of Ksolubilizers as a K- biofertilizers.

During 2006 Parthenium hysterophorus L. plant material was collected from the Agricultural Research Farm, B.H.U. during the rainy and winter season, to investigate changes in content of the some biochemical compounds in different plant parts (root, stem and leaf). High content of both protein and starch was recorded in leaves in both seasons. The content of reducing sugars and carbohydrates were higher during rainy season in all parts of Parthenium as compared to the winter season, while non- reducing sugars were highest in leaf material during the rainy season as compare to winter season.

In statistically designed 14 field experiments, culture suspension of specific Rhizobium and other bacterium (Azotobacter/Beijerinckia/Pseudomonas-PO4 solubilizer) was used singly and/or combinedly along with gum acacia sticker for plotwise seed inoculation of gram (9;I0 & I with 3 cultivars; I0, I1 & I2 at 3 P levels; 17; and 13 treatments in trial No. 1&2; 3&4;5;6&7; and 8 respectively), pea (12 treatments in trial No. 9 & 10, 11, and 12 at soil pH 7.5, 9.5 and 8.5 respectively) and lentil (12 treatments in trial No. 13&14). Every plot (5×2 m2) of each trial was basaly dressed at the rate of 20 kg N(urea) and 50 kg P2O5 (super phosphate) per ha. Extra levels of P2O5 used some treatments of the last 4 trials on gram were not beneficial.

The release of K from waste mica (muscovite and biotite) was tested with 4 K-solubilizing isolates collected from maize rhizosphere, for 7, 14 and 21 days of incubation at 28 ± 2°C. K-solubilization by different bacterial isolates showed significant change on muscovite and biotite powder supplemented plates and the amount of K released varied from 1.28 - 46.75 μg/ml. The soluble K contents in all isolated treatments were significantly higher than control. Herein, isolate KSB 2 had higher K-solubilization ability when compared with other isolates (KSB 1 , KSB 3 and KSB 4 ) in vitro DOI: http://dx.doi.org/10.3329/bjb.v43i2.21680 Bangladesh J. Bot. 43 (2): 235-237, 2014 (September)

That rhizobial strains belonging to pulses not only differ among themselves but also show differences in their effectiveness when Azotobacter isolates are used as co-inoculants has been shown by Sanoria & Ram (1979) and Sanoria & Mallik (1981). This has now been further demonstrated in trials conducted over 2 years using bengal gram. These trials also included a phosphate solubilizing bacterium (Pseudomonas spp.) as an extra inoculant but it had no effect on the responses obtained.