In vitro production of growth regulators and phosphatase activity by phosphate solubilizing bacteria

Crops absorb phosphorous in the form of soluble orthophosphate ion. The solubility of phosphate is inhibited by the presence of iron and aluminium in acidic soils and calcium in neutral and alkaline soils. This leads to fixation of phosphorous, making it not available to crop plants. The phosphate solubilizing bacteria (phosphobacteria) secretes some kinds of organic acids which act on insoluble phosphates and convert the same into soluble form, thus providing phosphorous to plant. An experiment was conducted to enumerate the population density of phosphobacteria in the rhizosphere soils of brinjal, chilly, cotton, green grain, groundnut, maize, paddy, ragi, sorghum and turmeric using Ketznelson and Bose medium following dilution plate technique. Efforts have been made to isolate phosphobacteria from these soils and isolated strains were inoculated in specific media containing specific substrates to produce growth regulating substances such as IAA and GA3 and phosphatase enzyme. The result showed that the population levels of phosphobacteria were higher in the rhizosphere soil of groundnut plant. Further, all the strains of phosphobacteria were able to produce phytohormones and phosphatase enzyme under in vitro conditions.Keywords: In vitro, phosphobacteria, growth regulator

In vitro multiplication of Ocimum gratissimum L. through direct regeneration

The objective of this study was to develop a rapid system for regeneration of the important medicinal plant, Ocimum gratissimum L, from nodal explant. Single node explants were inoculated on basal MS (Murashige and Skoog, 1962) medium containing 3% (w/v) sucrose, supplemented with differentconcentrations and combinations of 6-benzylaminopurine (BAP), kinetin (KN), indole-3-acetic acid (IAA) or indole-3-butyric acid (IBA) for direct plant regeneration. Maximum numbers of shoot (14.3±1.5) were observed on the medium containing 0.5 mg/l BAP and 0.25 mg/l IAA after four weeks of culture. Regenerated shoots were separated and rooted on same half strength MS medium supplemented with 0.5 mg/l of IAA alone for three weeks. Well-developed complete plantlets were transferred on to speciallymade plastic cup containing soilrite. Acclimatized plantlets were successfully grown in garden soi

Antimicrobial activity of important Indian medicinal plants against Pyogenic infection

The antimicrobial activity of crude extracts of five medicinal plants used in traditional Indian medicine was tested against five   important  pyogenic bacteria.They are Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa.Streptococcus pneumoniae. Of the five medicinal plants used only three were showed considerable antimicrobial activity against one or more species of microorganisms tested. Among the three solvents used the most effective extract was found to be methanol extraction. The most effective antimicrobial plant was identified as Glycyrriza glabra followed by Dathura metal, Coccinia grandis. Least activity was observed in  Sida spinosa, and Lab lab purpureus.       ÂÂ

Studies on nutrient solubilization, biocontrol and plant growth promoting traits of Burkholderia cepacia from tea soil

A study was undertaken to isolate a novel indigenous bacterial strain namely Burkholderia cepacia from tea soils to solubilize potassium (K) and phosphorus (P) sources respectively. The isolated strain was screened based on its solubilization potential in both broth and agarized medium amended with various K and P sources. Plant growth promoting traits and biocontrol activity of the purified strain against tea pathogens such as Pestalotiopsis theae, Glomerella cingulata, Poria hypolateritia, Phomopsis theae and Hypoxylon serpens were studied. Results revealed a significant solubilizing zone in agar medium blended with muriate of potash (MOP) (2.0 cm), sulphate of potash (SOP) (1.2 cm), rock phosphate (1.6 cm) and single super phosphate (0.8 cm). The release of available K was quantified in liquid medium supplemented with MOP and was found to be higher (41.5 mg L-1) than SOP. Among different P sources, rock phosphate (35.2 mg L-1) showed higher solubilization than single super phosphate (30.2 mg L-1) by the test organism on 5th day of incubation. B. cepacia was found to produce a large amount of bioactive compounds like siderophore (12.3 μg mL-1), IAA (263.3 μg mL-1) and GA3 (14.9 μg mL-1) including exo-polysaccharides (46.8 ppm). The test organism also showed a remarkable biocontrol activity against P. theae (52.5%), G. cingulata (42.5%), H. serpens (47.5%), Phomopsis theae (32.7%) and P. hypolateritia (30.9%). The secondary metabolites production by an efficient strain B. cepacia revealed that the strain could produce a wide range of volatile compounds

A growth walk model for estimating the canonical partition function of Interacting Self Avoiding Walk

We have explained in detail why the canonical partition function of Interacting Self Avoiding Walk (ISAW), is exactly equivalent to the configurational average of the weights associated with growth walks, such as the Interacting Growth Walk (IGW), if the average is taken over the entire genealogical tree of the walk. In this context, we have shown that it is not always possible to factor the the density of states out of the canonical partition function if the local growth rule is temperature-dependent. We have presented Monte Carlo results for IGWs on a diamond lattice in order to demonstrate that the actual set of IGW configurations available for study is temperature-dependent even though the weighted averages lead to the expected thermodynamic behavior of Interacting Self Avoiding Walk (ISAW).Comment: Revised version consisting of 12 pages (RevTeX manuscript, plus three .eps figure files); A few sentences in the second paragraph on Page 4 are rewritten so as to make the definition of the genealogical tree, ${\cal Z}_N$, clearer. Also, the second equality of Eq.(1) on Page 4, and its corresponding statement below have been remove

Efficacy of certain fungicides against Phomopsis theae under in vitro conditions

Four contact fungicides, Blitox (copper oxychloride), Kocide (copper hydroxide), Mancozeb (dithane M-45) and Bordeaux mixture and four systemic fungicides, Baycor (bitertanol), Calixin (tridemorph), Contaf (hexaconazole) and Bavistin (carbendazim) were evaluated against Phomopsis theae under in vitro condition. The results indicated that carbendazim was found to be the most effective in suppressing the growth followed by dithane M-45. Among the different concentrations tested, carbendazim at 4 ppm and dithane M-45 at 8 ppm were found to be optimum for the control of pathogen’s growth.Keywords: Phomopsis theae, fungicides, in vitro screening, phomopsis canke

Significance of secondary metabolites and enzymes secreted by Trichoderma atroviride isolates for the biological control of Phomopsis canker disease

Phomopsis theae Petch, the causative agent of Phomopsis canker diseases, is one of the major constrain in tea plants. The present study deals with development of efficient biological control agent against canker based on the secretion of several secondary metabolites and defense enzymes under in vitro conditions. Among the isolates evaluated, the antifungal compounds obtained from Tv1 Trichoderma atroviride was able to inhibit the growth of pathogen and showed 100% inhibition at concentration of 500 ppm. Synthesis of extracellular enzymes such as amylase, cellulase, polygalacturonase, protease and chitinase correlate with the antagonist activity of the isolates and maximum enzymatic activity was observed for Tv1 isolates followed by Tm3 and Tc3 isolates. The antifungal compounds responsible for the biological control activity were characterized through gas chromatography - mass spectroscopy (GC-MS) analysis.Key words: Trichoderma atroviride, Phomopsis theae, tea plants, antifungal compounds, enzymatic activity