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Aluminum (Al), the third most abundant element overall, after silicon and oxygen, is found virtually in all food, air, soil and water. Under acidic conditions, Al is solubilized into [Al(H 2 O) 6 ] 3+ , which is highly toxic to many plant species. Present paper reviewed Al toxicity and tolerance mechanism in agricultural plants with special reference to cereals and legumes. Even at micromolar concentrations, cell division in the root tip meristem in sensitive plants is quickly inhibited by Al 3+ . Expressing the species-dependent manner of response, growth enhancement at low concentrations of Al 3+ is also reported from some plants such as soybean. Plasma membrane can be identified as the primary target of Al toxicity, where production of higher reactive oxygen species and higher fatty acid peroxidation has been observed due to alteration of plasma membrane integrity. Though, toxicity and the mechanisms attributed to Al-resistance are extremely complex phenomena, exclusion is widely accepted as the key mechanism involved in detoxifying Al 3+ . Exudation of chelating ligands, formation of pH barrier at the rhizosphere or at root apoplasm, cell wall immobilization, selective permeability of the plasma membrane, and Al efflux have been proposed as the possible mechanisms for Al exclusion. Al-induced exudation in cereals and legumes is dominated by citrate, malate, and oxalate in varying degrees depending on the species and/or cultivar. Apart from sensitive cultivars, moderately tolerant or tolerant cultivars can also be distinguished from various kinds of cereals and legumes. However, reliable techniques for screening such resistant genotypes have not been developed for any economically important crops.

BACKGROUND:Certain crop-based waste materials have been recognized as cost-effective and highly efficient adsorbents for removal and recovery of different kind of heavy metals from aqueous solutions. The ability is strongly attributed to the carboxyl functional group of some pectin substances such as galacturonic acid often found in fruit peels. The present manuscript was aimed at assessing the potential applicability of banana peel for metal removal from contaminated waters. METHODS AND RESULTS:As revealed by laboratory investigations, banana peel contains pectin (10-21%), lignin (6-12%), cellulose (7.6-9.6%), and hemicelluloses (6.4-9.4%). The pectin extraction is reported to have glucose, galactose, arabinose, rhamnose, xylose, and galactouroninc acid. Several studies conducted under different conditions proved that banana peel is capable of adsorbing 5. 71, 2.55, 28.00, 6.88, 7.97, and 5.80 mg/g of Cd

Phosphate solubilizing microorganisms (PSMs) offer an ecologically acceptable mean for converting insoluble phosphate to soluble forms making them available for plants to absorb. Several bacterial strains (Pseudomonas, Bacillus, Rhizobium and Enterobacter) and fungal strains (Aspergillus and Penicillium) have so far been recognized as powerful phosphate solubilizers. Insoluble phosphates are converted into available forms by phosphate solubilizing microorganisms via the process of acidification, chelation, exchange reactions and production of organic acid. Though phosphorus is found to be a limiting factor in many soils, application of PSMs as biofertilizers or bioconverters for solubilizing fixed phosphorus has not yet been successfully practiced. In this context, isolation, identification and characterization of soil PSMs are considered to be effective in broadening the spectrum of phosphate solubilizers available for field application.

Purpose : Combine use of phosphate solubilizing microorganisms and organic manure has greater agronomic utility as it could improve phosphorous (P) utilization efficiency through conversion of insoluble P to accessible forms. Therefore, the present study was conducted to assess the effect of different organic manures (poultry manure, goat manure and cow dung) with phosphate solubilizing microorganism on phosphorous availability. Research Method : The phosphate solubilizing bacterial (PSB) strain employed in this study was isolated from soil samples collected from agricultural lands in Matara District of Sothern Sri Lanka. The strain was identified as Enterobacter cancerogenous. Eight treatment combinations each replicated three times were used in the study. Findings : P availability of organic manure amended soils was progressively increased irrespectively the inoculation of PSB strain. The bulk of the increment occurred during the first 2 to 3 weeks of the incubation followed by slight reductions at the later stages. P availability of the soil amended with organic manures was significantly (P ≤ 0.05) higher than that of the control. Furthermore, the specified were much higher when PSB was inoculated to the soil amended with organic manures. PSB inoculants were used with poultry manure showed the highest P availability. Originality / Value : The availability of soil phosphorous is enhanced by combine use of organic manures and PSB inoculants; the practice is suggested to be employed in integrated nutrient management strategies.

The aim of this work was to isolate phosphate solubilizing bacteria (PSB) and assess their effect on the growth of mung bean (Vigna radiata [L.] R. Wilczek) plants. Of 31 isolated PSB strains, two efficient strains, identified as Pantoea agglomerans (PSB-1) and Burkholderia anthina (PSB-2), were employed in further studies. Maximum P solubilization (720.75 µg mL -1 ) was recorded from the cultures co-inoculated with P. agglomerans and B. anthina. A strong positive correlation was found between pH and soluble P concentration in the medium, as well as between titratable acidity and P solubilization. Both strains under greenhouse conditions remarkably enhanced shoot and root length, shoot and root dry matter, and P uptake of mung bean plants. Growth was found to be further improved by adding tricalcium phosphate (TCP) with PSB inoculation. Co-inoculation of both PSB strains and adding TCP exhibited the highest growth performances and P uptake of mung bean plants; this implies that their applicability as a promising alternative to minimize the P problem in agricultural soils.

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A total of 35 phosphate solubilizing bacterial strains were isolated from waste mushroom bed of Agaricus bisporus in Buyeo-Gun, Chungnam and screened for the production of indole acetic acid (IAA). The best IAA producing strain was identified as Pantoea rodasii using 16S rRNA analysis. In addition to the IAA production, this strain could act as an efficient phosphate solubilizer (1100 µg ml -1 after 5 days of incubation) also. The selected strain was cultured under different conditions in order to assess the optimum conditions for maximum IAA production. The nutrient broth (NB) medium was recorded as the best medium, where the maximum IAA production (229 µg ml -1) was recorded at the start of stationary phase (12 hours after inoculation) of the bacteria growth. The performance of the strain was found to be maximum at the temperature of 30 o C followed by 25 o C. IAA production was found to be increased with increasing tryptophan concentration (from 0.1 to 0.6%), however beyond this limit, a slight reduction in IAA production was observed. The strains' ability to produce IAA was further confirmed by extraction of crude IAA and subsequent TLC analysis. A specific spot from the extracted IAA preparation was found corresponding with the standard spot of IAA with same R f value. The results of HPLC analysis conducted in identifying and quantifying the IAA production more precisely, are in agreement with the results of the assessment done with colorimetric method. As revealed by the results of the pot experiment, the isolated strain could significantly enhance the growth (as measured by shoot and root growth) of mung bean plants compared to that of non-inoculated plants. Therefore it can be concluded that the present strain, Pantoea rodasii has great potential to be used as bio-inoculants.