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Background: Rice is one of the major staple crops of human population. Worldwide escalating human populace exerts pressure to increase rice production. To fulfill the demand, the injudicious application of chemical fertilizers is posing grave threat to the environment together with the entire living population. A suitable replacement of these harmful fertilizers is needed in modern agriculture to keep the biodiversity undisturbed. The main objective of the study is to screen and explore indigenous plant growth promoting fungi which can replace the conventional fertilizers. Methods: Rhizospheric soil of different rice cultivating fields were collected in the year 2018. Different in vitro assays of the fungal isolates obtained from the soil were performed to check their plant growth promotion capabilities. Result: 20 different indigenous fungal isolates were studied to evaluate their ability as PGPF for organic cultivation of Tulaipanji, an endemic aromatic rice variety cultivated in Uttar Dinajpur, West Bengal, India. Trichoderma harzianum TaK12 and Trichoderma aureoviride TaN16 were found to enhance maximum shoot and root length of rice plant. These two isolates also showed efficacy in phosphate solubilization. Trichoderma aureoviride TaN16 together with Penicillium citrinum PcK10 and Aspergillus niger AnK1 produced high amount of IAA. The results obtained from the study clearly indicate that these plant growth promoting fungi (PGPF) possess the ability to boost up plant growth. [ABSTRACT FROM AUTHOR]

The study profiled the volatiles in Mentha longifolia, M. piperita and M. spicata and examined the effect of plant growth regulators (PGRs) - IAA, NaDK and SA on the modulations of volatile organic compounds (VOCs) in M. spicata. GC-MS was used to analyze and identify the compounds in hexane extractions from the selected Mentha sp. Sixteen metabolites belonging to monoterpenes, sesquiterpenes, esters, ethers, ketones, phenols and carbobicyclic compounds were detected. Some important metabolites viz., β-pinene, 1,8-cineol, 1,4-benzenediol, 2,5-dimethyl-, (Z)-β–caryophyllene, cis-β-farnesene, cis-muurola-4 (14),5-diene, germacrene D were found which increased in their relative concentrations compared to control after PGRs treatment. [ABSTRACT FROM AUTHOR]

Abstract: Twenty-one isolates of phosphate solubilizing-indole acetic acid producing rhizobacteria (PSIRB), 20 isolates of phosphate solubilizing rhizobacteria (PSRB) and 42 isolates of indole acetic acid producing rhizobacteria (IRB) were isolated from 49 rhizospheric soil samples of tomato (Lycopersicon esculentum Mill.) collected from tomato growing regions of Karnataka. A method combining Pikovskaya’s and Bric’s technique was developed to isolate PSRIB, PSRB and IRB’s. The selected isolates were further analyzed for their ability to solubilize calcium phytate. Based on the root colonization assays and the abilities of bacterial isolates to increase the seed germination and seedling vigor under laboratory conditions, five isolates were selected from each group for further studies. Under greenhouse conditions, all the selected rhizobacteria isolates significantly increased root length, shoot length, fresh weight, dry weight and total phosphorus content of 30-day-old-seedlings with respect to control. Isolate PSIRB1 and IRB36 significantly reduced the Fusarium wilt incidence over other isolates of same and other group, and the control. On the basis of results from laboratory and greenhouse studies, one bacterial isolate from each group was selected for plant growth and yield analysis studies. Isolate PSIRB2 showed increased plant height, fresh weight, number of fruits per plant and average weight of fruit over PSRB9, IRB36 and untreated controls. Studies on the nature of protection offered by these bacterial isolates following split-root technique revealed that the isolates PSIRB2 and PSRB9 had the ability to induce systemic resistance. One isolate, IRB36 appeared to protect the tomato seedlings through direct antagonism. [Copyright &y& Elsevier]

The current study investigates the functional diversity of bacterial community existing as a biofilm on the root surface of water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.) grown in Yamuna river, Delhi, India. Forty-nine bacterial isolates recorded a diverse pattern of susceptibility/resistance to 23 antibiotics tested. Most of the bacterial isolates were susceptible to Ofloxacin, Ciprofloxacin, Ceftriaxone, Gentamicin, and Cefepime and resistant to Ceftazidime, Nitrofurantoin, Ampicillin, and Nalidixic acid. Isolate RB33-V recorded resistant against 11 antibiotics tested, and RB42-V was found susceptible to most of the antibiotics tested. Among the seven heavy metals tested, the highest of 39 bacteria showed resistance to zinc, and least of 9 bacteria recorded resistance against cadmium. Isolate RB20-III was susceptible to all heavy metals tested, and RB23-III was found resistance for six heavy metals tested. A higher correlation was observed with zinc and multiple antibiotic resistance, and Ceftazidime resistance was most frequently associated with all the heavy metals tested. These bacteria grow optimally under neutral-alkali conditions and susceptible to acidic conditions, and they can withstand a broad range of temperatures and salt concentrations. They are very poor in phosphate solubilization. Further, the bacteria recorded varied results for beneficial traits, hemolytic, and DNase activity. The results of bacterial characterization indicated that this bacterial community is of multi-origin in nature and are assisting the host-plant in withstanding the adverse and fluctuating conditions of the Yamuna river by reducing the toxic effect of heavy metals, antibiotics and other xenobiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Beneficial plant-associated bacteria play a key role in supporting and/or promoting plant growth and health. Plant growth promoting bacteria present in the rhizosphere of crop plants can directly affect plant metabolism or modulate phytohormone production or degradation. We isolated 355 bacteria from the rhizosphere of rice plants grown in the farmers' fields in the coastal rice field soil from five different locations of the Ganjam district of Odisha, India. Six bacteria producing both ACC deaminase (ranging from 603.94 to 1350.02 nmol α-ketobutyrate mg(-1)  h(-1) ) and indole acetic acid (IAA; ranging from 10.54 to 37.65 μM ml(-1) ) in pure cultures were further identified using polyphasic taxonomy including BIOLOG((R)) , FAME analysis and the 16S rRNA gene sequencing. Phylogenetic analyses of the isolates resulted into five major clusters to include members of the genera Bacillus, Microbacterium, Methylophaga, Agromyces, and Paenibacillus. Seed inoculation of rice (cv. Naveen) by the six individual PGPR isolates had a considerable impact on different growth parameters including root elongation that was positively correlated with ACC deaminase activity and IAA production. The cultures also had other plant growth attributes including ammonia production and at least two isolates produced siderophores. Study indicates that presence of diverse rhizobacteria with effective growth-promoting traits, in the rice rhizosphere, may be exploited for a sustainable crop management under field conditions., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)