1,721,028 research outputs found
Genetic Diversity of Soil Bacteria
Full text linkThe Special Issue “Genetic Diversity of Soil Bacterial Communities” collected research and review articles addressing some relevant and unclear aspects of the composition and functioning of bacterial communities in rich or marginal agricultural soils, in field trials as well as in laboratory-scale experiments, at different latitudes and under different types of management
Solubilization of insoluble zinc compounds by zinc solubilizing bacteria (ZSB) and optimization of their growth conditions
No full textIn this research, the optimum growth conditions for two zinc solubilizing bacteria (ZSB) have been studied for their potential application as bioinoculants to overcome Zn unavailability in soils. For this purpose, a laboratory-scale experiment was carried out to evaluate the zinc solubilizing ability of 80 plant growth promoting bacteria (PGPB) strains isolated from the rhizosphere of barley and tomato plants. To select effective ZSB, isolates were evaluated on Tris-mineral medium supplemented separately with zinc oxide, zinc carbonate, and zinc phosphate at a concentration of 0.1%. Two strains (Agrobacterium tumefaciens and Rhizobium sp.) were selected, based on a clear halo zone around their colonies in the solid medium supplemented with zinc oxide after 10 days of incubation at 29 °C. Results of solubilization at different pH values showed that these strains had solubilization activity in the range of pH 8-10 while no solubilization was observed at pH 6 and 7. The maximum Zn solubilization values were noted at pH 9: 51.4 mg L-1 (Agrobacterium tumefaciens) and 72.1 mg L-1 (Rhizobium sp). According to findings, bacterial growth was affected by different NaCl concentrations under in vitro condition. The salt concentration required for 50% inhibition of absorbance was 2.11 and 2.27% NaCl for Agrobacterium tumefaciens and Rhizobium sp., respectively. The maximum bacterial growth was observed at about 0.8% NaCl concentration
Changes in photo-protective energy dissipation of photosystem II in response to beneficial bacteria consortium in durum wheat under drought and salinity stresses
Full text linkThe present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy
Photosynthetic responses of durum wheat to chemical/microbiological fertilization management under salt and drought stresses
No full textThe current research was carried out to evaluate the stress tolerance potential of durum wheat plants, in response to the inoculation of native plant growth-promoting bacteria (PGPB), through assessing PSII photochemistry and photosynthetic traits, as well as grain yield and plant height, and to investigate the possibility of using PGPB as a sustainable alternative or in combination with traditional fertilization plans. A greenhouse experiment included chemical/microbiological fertilization and stress (salinity and drought) treatments. The results indicated that the application of bacterial consortium of four PGPB markedly augmented some biochemical and functional traits in photosystem II, such as effective quantum yield of PSII photochemistry (Y(II)), electron transport rate of PSII (ETR), photosynthesis capacity, transpiration rate and stomatal conductance in unstressed plants, and prevented severe changes in the mentioned traits under drought and salinity conditions. The application of PGPB contributed to enhanced grain yield, too. Furthermore, a better performance of the PGPB inoculation was found in combination with half-dose of the recommended chemical fertilizers. In conclusion, PGPB inoculants maintain or improve the photosynthesis efficiency of durum wheat, grain yield and plant height, particularly under stress conditions, and can help to minimize the consumption of chemical fertilizers
Characterization of soil microalgae and cyanobacteria in a differentially managed olive orchard
No full textAmeliorative Effects of PGPB on Yield, Physiological Parameters, and Nutrient Transporter Genes Expression in Barattiere (Cucumis melo L.)
No full textThe intensive application of chemical fertilizers to overcome deficiency of nutrients and achieve maximum agricultural productivity has led to environmental impacts. A significant strategy for sustainable management, by decreasing the use of chemical fertilizers, can consist in the technology based on suitable levels of fertilization in combination with plant growth-promoting bacteria (PGPB) inoculation. This work aimed to test in vivo a consortium of three PGPB, previously isolated and characterized in vitro, on Barattiere plants (Cucumis melo L.). Plants were grown in a soilless system at the commercial dose of mineral fertilizer and at half dose, in order to evaluate the effects of these microorganisms on plant physiology, yield, and the transcriptional expression of four genes involved in NH4+ (AMT2), Fe (FRO, IRT1), and Pi (PHT1) transport and uptake by plant. Our results indicate that even in a soilless pot experiment, where a mineral nutrition solution is used, the bacterial consortium of PGPB improves fruit yield and early maturity, some physiological parameters, and upregulates the expression of some key genes related to N, Fe, and Pi plant nutrition, remarking the environmental and economic gains deriving from the use of half dose of mineral fertilizer
Agroecosystem diversification and sustainable management lead to increased biodiversity, crop production and socio-economic advantages: a case-study of an Italian olive orchard
Full text linkCaratterizzazione molecolare delle comunità batteriche in coltivazione tradizionale e sostenibile di olivo
No full textLe diverse pratiche di gestione del suolo sono in grado di influenzare e di stimolare l’attività e la composizione delle comunità batteriche e fungine presenti. Le tecnologie di gestione sostenibili, fondate sull'inerbimento, sull'apporto di ammendanti organici microbiologicamente stabilizzati, sul riciclo dei residui colturali in campo, sulla non-lavorazione hanno come obiettivo quello di incrementare la fertilità chimica e biologica del suolo, sequestrare carbonio atmosferico e creare condizioni di disponibilità nutrizionali contenute opportunamente integrabili con interventi fertilizzanti a basso impatto ambientale (fertirrigazione e concimazione fogliare).
L’obiettivo di questo studio è stato quello di comparare, in ambiente semi-arido mediterraneo, in sistema frutticolo pesco e actinidia, l’effetto di pratiche di gestione del suolo innovative e convenzionali sulla composizione e sull’attività delle comunità microbiche telluriche utilizzando una combinazione di tecniche molecolari e microbiologiche.
Sono state comparate due tesi: una “innovativa” (non-lavorazione del suolo, fertilizzazione guidata e apporto di matrici organiche,compost e residui di potatura) e una “convenzionale” (lavorazione del suolo, fertilizzazione minerale ordinaria senza apporto di compost e con allontanamento dei residui di potatura). In ciascuna tesi il campionamento dei suoli è stato effettuato a metà febbraio ed ha interessato lo strato 0-20 cm. Il campione di analisi è derivato dalla composizione di 20 sub-campioni. Per il pescheto è stata effettuata anche una distinzione di campionamento tra filari ed interfilari.
Il DNA e l’RNA totale sono stati estratti dal suolo mediante un metodo diretto (FastPrep System, MP Biomedicals e RNA Power Soil Total RNA isolation kit, MO BIO). L’RNA estratto è stato retro-trascritto utilizzando il kit RETRO script Reverve Transcription for RT-PCR (AMBION). DNA e c-DNA sono stati amplificati con due differenti coppie di primer: 968F-1401R per amplificare una regione di 500 bp del 16S r-DNA e FF390-FR1-GC per l’amplificazione specifica di una regione di 390 bp del 18S r-DNA. I profili fingerprint del DNA e dell’RNA sono stati visualizzati e comparati mediante gel elettroforesi su gradiente denaturante (DGGE). I profili metabolici delle comunità microbiche (BIOLOG) sono stati valutati inoculando le popolazioni estratte in piastre contenenti 31 diverse fonti di carbonio (ECO-Microplates, BIOLOG)
Metadata analysis to evaluate environmental impacts of wheat residues burning on soil quality in developing and developed countries
Full text linkCrop residues are widely considered as a biofuel source and used in livestock feeding, or are burned off to clean the field for tillage and planting. Nonetheless, crop residue burning poses serious threats to the soil stability and sustainability of the food chain. This study aimed to investigate the potential environmental impacts of wheat residues burning on declines in soil quality in developing (Iran) and developed (Italy) countries by analyzing metadata of the last 50 years. All metadata were provided from the ‘Food and Agriculture Organization of the United Nations’ (FAO) including wheat harvested area, annual production, and biomass burning, to assess the potential impact of crop residue burning on soil quality. In detail, the greenhouse gases (GHGs) emission, and energy and nutrient losses by the wheat residues burning were estimated. Our results showed a robust interdependence between wheat residues burning and environmental effects in both developed and developing systems. Accordingly, the global warming potential increased in Iran (4286 to 5604 kg CO2eq) and decreased in Italy (3528 to 1524 kg CO2eq) over the last 50 years. Amongst all nutrient losses, nitrogen represents the higher lost value in both countries, followed by potassium, sulfur, and phosphorus
Isolation of bacteria with potential plant promoting traits and optimization of growth conditions
Full text linkThis research aimed at investigating the isolation and identification of bacterial strains with biological nitrogen-fixing
capability and phosphate, potassium, and zinc solubilization activities from a durum wheat field under two different tillage practices including 10 years of conventional tillage (CT) and no-tillage (NT) practices. Attempts were also extended to
estimate their relative abundances in the soil as well as to develop accurate mathematical models in determining the effect of different temperatures, NaCl concentrations and pH on the growth, and activity of selected isolates. Twelve effective bacterial strains, including Pseudomonas, Acinetobacter, and Comamonas genera, were identified with a great potential to solubilize the insoluble forms of phosphate (from 11.1 to 115.5 mg l−1 at pH 8), potassium (from 32.2 to 35.6 mg l−1 at pH 7), and zinc (from 1.11 to 389.90 mg l−1 at pH 9) as well as to fx N2 gas (from 19.9 to 25.2 mg l−1). To our knowledge, this is the frst report of the ability of Comamonas testosteroni and Acinetobacter pittii to fix nitrogen and to solubilize insoluble potassium compound, respectively. Three families, Moraxellaceae, Pseudomonadaceae, and Comamonadaceae, showed a higher percentage of abundance in the NT samples as compared to the CT, but only significant difference was observed in the relative abundance of Pseudomonadaceae (P<0.01). These strains could be definitely recommended as inoculants to promote plant growth in the wide ranges of pH, salinity levels (with maximum growth and complete inhibition of growth from 0.67–0.92% to 3.5–9.3% NaCl, respectively), and temperatures (2.1–45.1 °C)
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