Nurgul Kitir

Role of inoculation with multi-trait rhizobacteria on strawberries under water deficit stress@@@Augimą skatinančiomis rizobakterijomis inokuliavimo įtaka braškėms esant vandens stygiaus stresui

This study was conducted during 2011 and 2012 to evaluate the effect of 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing, N2-fixing and P-solubilizing bacteria on the yield and morpho-physiological parameters of strawberry. A total of 8 applications at the trial set, with four water regimes were randomly distributed into the pots. The diminishing water supply caused a gradual decrease in the plant growth, chlorophyll content and berry yield, accompanied by increasing activities of drought stress markers such as total phenolics content (TPC), trolox equivalent antioxidant capacity (TEAC), malondialdehyde (MDA) content, hydrogen peroxide (H2O2), glutathione reductase (GR), glutathione S-transferase (GST), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) in the leaves of strawberry. The multi-trait bacteria also increased plant growth and yield as well as TPC, TEAC, antioxidant enzymes (GR, GST, CAT, POD, SOD and APX) activity, phytohormone (GA, SA and IAA) and the contents of N, P, K, Ca, Fe, Mn, Zn and Cu, but decreased MDA and H2O2 contents which may contribute in part to activation of physiological and biochemical processes involved in the alleviation of the effect of drought stress.

The reuse of reclaimed water for irrigation around the Mediterranean Rim: a step towards a more virtuous cycle?

Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both quantity and quality. High-quality water should be primarily reserved to drinking water while reclaimed water is an alternative for other usages. A review of situations in Tunisia, Jordan, France, and Italy involving the use of reclaimed water highlights the disparity in national regulations governing this alternative water resource and in its management. On the first hand, the use of recycled water for irrigation can have an adverse impact on public health and the environment, depending on treatment and irrigation practices. On the other hand, it may also represent a new source of water: wastewater should no longer be considered as waste but, rather, as a new resource to be handled in a circular economy-type loop. Current scientific knowledge in agronomic and environmental sciences, as well as in the economic and social sciences, can be integrated and used to lower the associated risk through the effective management of irrigation using recycled water and to address the following questions: (i) How can the time-varying nutrient needs of crops be managed to operate safe environmental reuse within an adapted risk assessment framework? (ii) What socio-economic models can render this integrated approach sustainable? (iii) What treatment systems and irrigation technology can be used to support these ideas and with what information? (iv) What changes in the regulations are needed?

Making Soil More Accessible to Plants: The Case of Plant Growth Promoting Rhizobacteria

Plant Growth Promoting Rhizobacteria (PGPR) are beneficial soil bacteria that can live either symbiotically with plants at rhizosphere or as endophytes living on or inside of the host plants. There are two main mechanisms via PGPR contribute to the plant growth. Direct mechanism consists of phytohormone production (i.e. auxins (IAA), cytokinins and gibberellins), biological nitrogen fixation, solubilizing inorganic phosphates, mineralizing organic phosphate and producing organic matter such as amino acids. As indirect mechanisms, PGPR aid plants in combat against the pathogen microorganisms by means of stimulating the disease-resistance mechanism of plants, promote favorable symbiosis, decontaminate the soil of xenobiotics. PGPR can also help plants to cope against abiotic stress by lowering ethylene levels, or against pathogenic microorganism by means of secreting antibacterial/antifungal substances. Exact mechanisms of PGPR characteristics which stimulate the plant growth or product formation are still under investigation, yet in agriculture, PGPR are used as environmental friendly biofertilizers, biocontrol agents or biostimulants. These beneficial bacteria are usually introduced to the plants either in powder or liquid form or the seeds are covered with the inoculants before sowing. Plants are subject to many different environmental elements. Abiotic factors such as drought or water stress have been one of the main plant growth limiting factors. Agricultural PGPR application is an alternative solution against loss due to the environmental stresses, since breeding a plant with stress resistance trait is a very long and tricky process due to the fact that such traits are controlled by multiple genes. PGPR phytohormone and enzyme (i.e. ACC deaminase) production can decrease the stress levels of plants while enhancing the root structures.

The Role of Soil Beneficial Bacteria in Wheat Production: A Review

Free-living plant growth-promoting rhizobacteria (PGPR) have favourable effect on plant growth, tolerance against stresses and are considered as a promising alternative to inorganic fertilizer for promoting plant growth, yield and quality. PGPR colonize at the plant root, increase germination rates, promote root growth, yield, leaf area, chlorophyll content, nitrogen content, protein content, tolerance to drought, shoot and root weight, and delayed leaf senescence. Several important bacterial characteristics, such as biological nitrogen fixation, solubilization of inorganic phosphate and mineralization of organic phosphate, nutrient uptake, 1-aminocydopropane-1-carboxylic acid (ACC) deaminase activity and production of siderophores and phytohormones, can be assessed as plant growth promotion traits. By efficient use, PGPR is expected to contribute to agronomic efficiency, chiefly by decreasing costs and environmental pollution, by eliminating harmful chemicals. This review discusses various bacteria acting as PGPR, their genetic diversity, screening strategies, working principles, applications for wheat and future aspects in terms of efficiency, mechanisms and the desirable properties. The elucidation of the diverse mechanisms will enable microorganisms developing agriculture further.

Beneficial Role of Plant Growth-Promoting Bacteria in Vegetable Production Under Abiotic Stress

Changes in climate, natural or man induced, urbanization and several other factors result in abiotic stress, for example, high winds, extreme temperatures, drought, flood, etc. Such factors in turn affect many plants including vegetables. Vegetables, being plants grown for their vegetative parts, are, however, more sensitive to abiotic stress, when compared to grass family. The abiotic stress limits soil/climate for vegetable plantation and consequently results in decreased vegetable yields. Plant growth-promoting bacteria (PGPB) are beneficial soil bacteria capable of stimulating physical, chemical and biological changes in plants. In particular, for vegetables, there are numerous applications of these beneficial microorganisms to alleviate the adverse effects of abiotic stress. This review focuses on alternative mechanisms employed by PGPB to enhance vegetable production under various abiotic stresses, including drought, salinity, extreme temperature, nutrient and heavy metal stresses.

Integrated Use of Nitrogen Fertilization and Microbial Inoculation: Change in the Growth and Chemical Composition of White Cabbage

ABSTRACT Field experiments were conducted to evaluate the impact of seed and seedling inoculation by plant growth promoting rhizobacteria (PGPR) on nitrogen use efficiency, growth, yield, and chemical composition of cabbage at varying levels of nitrogen (N). Data revealed that N alone or in combination with PGPR either as seed or seedling inoculation significantly improved growth, yield, and nutrients of cabbage. PGPR inoculations were more efficient than non-inoculated controls in terms of yield and yield parameters. This study showed that seed and seedling inoculation increased yield and yield parameters as well as chlorophyll reading value and stomatal conductance versus controls. Applications of mineral fertilizers with microbial applications save 25% of mineral fertilizers yet give 33% more yield versus full doses of mineral application without microbial applications. Both seed and seedling treatments increased the nitrogen use efficiency (NUE) rates by 45, 53, 58, 45, and 40%, and 49, 59, 68, 69, 60, and 55%, respectively.

Effects of Root Plant Growth Promoting Rhizobacteria Inoculations on the Growth and Nutrient Content of Grapevine

ABSTRACT The objective of this study was to evaluate the effects of seven nitrogen (N2)-fixing and/or phosphorus (P)-solubilizing and siderophore-producing microorganism based bio-fertilizers in single and triple strain combinations isolated from the acidic rhizospheric soil of native tea, grapevine, and wild red raspberries. As a result of this study, bacterial efficiency was found to be variable and depended on the bacterial strains and evaluated growth parameters. Plant growth-promoting rhizobacteria (PGPR) has improved macro- and micro-nutrient concentrations in grapevine leaves, and stimulated plant growth. Triple inoculation and single inoculation based bio fertilizers were found to stimulate overall plant growth, including shoot and leaf weight, main shoot length, leaf ground index, chlorophyll, nitrogen, zinc and iron content of grapevine cv ‘Italy’. Bio-fertilizers increased the nutrients such as nitrogen, zinc and iron concentrations and consequently increased the chlorophyll content of the leaves.

Enzyme Dynamic in Plant Nutrition Uptake and Plant Nutrition

Soil contains enzymes, constantly interacting with soil constituents, e.g. minerals, rhizosphere and numerous nutrients. Enzymes, in turn, catalyse important biochemical reactions for rhizobacteria and plants, stabilize the soil by degrading wastes and mediate nutrient recycling.The available enzymes inside soil could originate from plants, animals or microbes. The enzymes that are produced from these organism could exhibit intracellular activities, at the cell membrane, interacting therefore with soil and its constituents, or extracellularly (so freely available). Therefore, vis-à-vis to plant nutrition, the (extra or sub) cellular localization has a key role. Typical major enzymes available in soil can be listed as dehydrogenases, hydrogenases, oxidases, catalases, peroxidases, phenol o-hydroxylase, dextransucrase, aminotransferase, rhodanese, carboxylesterase, lipase, phosphatase, nuclease, phytase, arylsulphatase, amylase, cellulase, inulase, xylanase, dextranase, levanase, poly-galacturonase, glucosidase, galactosidase, invertase, peptidase, asparaginase, glutaminase, amidase, urease, aspartate decarboxylase, glutamate decarboxylase and aromatic amino acid decarboxylase. An interesting strategy for improving the nutritional quality of the soil would be to inoculate microorganism to soil while giving attention to mineral or other compounds that affect enzyme activity in soil. Since, some elements or compounds could show both activation and inhibitory effect, such as Fe, Na, etc. metals, the regulation of their bioavailability is crucial.

Nonsymbiotic and Symbiotic Bacteria Efficiency for Legume Growth Under Different Stress Conditions

In order to achieve maximum crop yields, excessive amounts of expensive fertilizers are applied in intensive farming practices. However, the biological nitrogen fixation via symbiotic and nonsymbiotic bacteria can play a significant role in increasing soil fertility and crop productivity, thereby reducing the need for chemical fertilizers. It is well known that a considerable number of bacterial species, mostly those associated with the plant rhizosphere, are able to exert a beneficial effect on plant growth. The use of those bacteria, often called plant growth-promoting rhizobacteria (PGPR), as biofertilizers in agriculture has been the focus of research for several years. The beneficial impact of PGPR is due to direct plant growth promotion by the production of growth regulators, enhanced access to soil nutrients, disease control, and associative nitrogen fixation. Legumes play a crucial role in agricultural production due to their capability to fix nitrogen in association with rhizobia. Inoculation with nodule bacteria called rhizobia has been found to increase plant growth and seed yields in many legume species such as chickpea, common bean, lentil, pea, soybean, and groundnut. However, both rhizobia and legumes suffer heavily and adversely from various abiotic factors. The impact of different stress factors on both PGPR and legume production is critically reviewed and discussed.

Plant Growth Promoting Rhizobacteria's (PGPRS) Enzyme Dynamics in Soil Remediation

Soil is the basis of agriculture and consists of organic matters, minerals, water, and several gasses. All plants require soil both as an anchor to attach and as water and nutrient source. Unfortunately, lifestyles of humans, industrial progress, chemicals used in agriculture contaminate soil and cause soil pollution. A pollutant may be natural or human‐made in origin such as petroleum hydrocarbons, pesticides, heavy metals, and solvents. Since the quality of the soil affects the growth and product yield of plants, soil pollution is a crucial problem needs to be addressed urgently. Plant growth promoting rhizobacteria (PGPR) are microorganisms living in soil, on the plants roots, or inside the plant. PGPRs synthesize chemicals to stimulate plant growth and promote nutrient uptake, help degrading soil pollutants and fending off pathogens. While some pollutants can be degraded by enzymes produced by bacteria and fungi, degradation of heavy metals requires alternative methods. In this chapter, three enzymes produced by PGPRs are reviewed briefly. Aminocyclopropane‐1‐carboxylate (ACC) deaminase is responsible of lowering the ethylene levels of plants during stress conditions, whereas nitrogenase is responsible for N2 reduction to NH3. Moreover, phytase enables the degradation of phytate which is a main storage form of phosphate in plants.