Mechanisms and applications of plant growth promoting rhizobacteria: Current perspective

Soil bacteria are very important in biogeochemical cycles and have been used for crop production for decades. Plant–bacterial interactions in the rhizosphere are the determinants of plant health and soil fertility. Free-living soil bacteria beneficial to plant growth, usually referred to as plant growth promoting rhizobacteria (PGPR), are capable of promoting plant growth by colonizing the plant root. PGPR are also termed plant health promoting rhizobacteria (PHPR) or nodule promoting rhizobacteria (NPR). These are associated with the rhizosphere, which is an important soil ecological environment for plant–microbe interactions. Symbiotic nitrogen-fixing bacteria include the cyanobacteria of the genera Rhizobium, Bradyrhizobium, Azorhizobium, Allorhizobium, Sinorhizobium and Mesorhizobium. Free-living nitrogen-fixing bacteria or associative nitrogen fixers, for example bacteria belonging to the species Azospirillum, Enterobacter, Klebsiella and Pseudomonas, have been shown to attach to the root and efficiently colonize root surfaces. PGPR have the potential to contribute to sustainable plant growth promotion. Generally, PGPR function in three different ways: synthesizing particular compounds for the plants, facilitating the uptake of certain nutrients from the soil, and lessening or preventing the plants from diseases. Plant growth promotion and development can be facilitated both directly and indirectly. Indirect plant growth promotion includes the prevention of the deleterious effects of phytopathogenic organisms. This can be achieved by the production of siderophores, i.e. small metal-binding molecules. Biological control of soil-borne plant pathogens and the synthesis of antibiotics have also been reported in several bacterial species. Another mechanism by which PGPR can inhibit phytopathogens is the production of hydrogen cyanide (HCN) and/or fungal cell wall degrading enzymes, e.g., chitinase and s-1,3-glucanase. Direct plant growth promotion includes symbiotic and non-symbiotic PGPR which function through production of plant hormones such as auxins, cytokinins, gibberellins, ethylene and abscisic acid. Production of indole-3-ethanol or indole-3-acetic acid (IAA), the compounds belonging to auxins, have been reported for several bacterial genera. Some PGPR function as a sink for 1-aminocyclopropane-1-carboxylate (ACC), the immediate precursor of ethylene in higher plants, by hydrolyzing it into α-ketobutyrate and ammonia, and in this way promote root growth by lowering indigenous ethylene levels in the micro-rhizo environment. PGPR also help in solubilization of mineral phosphates and other nutrients, enhance resistance to stress, stabilize soil aggregates, and improve soil structure and organic matter content. PGPR retain more soil organic N, and other nutrients in the plant–soil system, thus reducing the need for fertilizer N and P and enhancing release of the nutrients.

Soil beneficial bacteria and their role in plant growth promotion: a review

Historically, management theory has ignored the constraints imposed by the biophysical (natural) environment. Building upon resource-based theory, this article attempts to fill this void by proposing a natural-resource-based view of the firm—a theory of competitive advantage based upon the firm's relationship to the natural environment. It is composed of three interconnected strategies: pollution prevention, product stewardship, and sustainable development. Propositions are advanced for each of these strategies regarding key resource requirements and their contributions to sustained competitive advantage.

A natural resource-based view of the firm

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil bacteria that aggressively colonize plant roots and benefit plants by providing growth promotion. Inoculation of crop plants with certain strains of PGPR at an early stage of development improves biomass production through direct effects on root and shoots growth. Inoculation of ornamentals, forest trees, vegetables, and agricultural crops with PGPR may result in multiple effects on early-season plant growth, as seen in the enhancement of seedling germination, stand health, plant vigor, plant height, shoot weight, nutrient content of shoot tissues, early bloom, chlorophyll content, and increased nodulation in legumes. PGPR are reported to influence the growth, yield, and nutrient uptake by an array of mechanisms. They help in increasing nitrogen fixation in legumes, help in promoting free-living nitrogen-fixing bacteria, increase supply of other nutrients, such as phosphorus, sulphur, iron and copper, produce plant hormones, enhance other beneficial bacteria or fungi, control fungal and bacterial diseases and help in controlling insect pests. There has been much research interest in PGPR and there is now an increasing number of PGPR being commercialized for various crops. Several reviews have discussed specific aspects of growth promotion by PGPR. In this review, we have discussed various bacteria which act as PGPR, mechanisms and the desirable properties exhibited by them.

Plant Growth Promoting Rhizobacteria: A Critical Review

Entrepreneurial intention is a rapidly evolving field of research. A growing number of studies use entrepreneurial intention as a powerful theoretical framework. However, a substantial part of this research lacks systematization and categorization, and there seems to be a tendency to start anew with every study. Therefore, there is a need to take stock of current knowledge in this field. In this sense, this paper carries out a review of the literature on entrepreneurial intentions. A total of 409 papers addressing entrepreneurial intention, published between 2004 and 2013 (inclusive), have been analyzed. The purpose and contribution of this paper is to offer a clearer picture of the sub-fields in entrepreneurial intention research, by concentrating on two aspects. Firstly, it reviews recent research by means of a citation analysis to categorize the main areas of specialization currently attracting the attention of the academic community. Secondly, a thematic analysis is carried out to identify the specific themes being researched within each category. Despite the large number of publications and their diversity, the present study identifies five main research areas, plus an additional sixth category for a number of new research papers that cannot be easily classified into the five areas. Within those categories, up to twenty-five different themes are recognized. A number of research gaps are singled out within each of these areas of specialization, in order to induce new ways and perspectives in the entrepreneurial intention field of research that may be fruitful in filling these gaps.

A systematic literature review on entrepreneurial intentions: citation, thematic analyses, and research agenda

The relationship between corporate social responsibility, job satisfaction, and organizational commitment: Case of Pakistani higher education

Purpose – The purpose of this paper is to investigate the service quality and its relationship to customer satisfaction among the customers of conventional banks and Islamic banks A modified SERVQUAL scale is utilized to ascertain the functional dimensions of service quality specific to the industry and service context under study In addition, the study examines the differences in service quality satisfaction and its impact on the behavioral intentions of customersDesign/methodology/approach – A field survey carried out with the help of a questionnaire constructed by using a modified SERVQUAL scale Data were collected from 200 walk‐in customers conveniently drawn from three major conventional banks and three Islamic banks located in urban areas of Pakistan Data were analyzed using the analytical hierarchy process to identify service quality and customer satisfaction‐related factors for Islamic and conventional banksFindings – By using factor analysis, 52 measurement items with a factor loading great

Service quality and customer satisfaction in the banking sector: a comparative study of conventional and Islamic banks in Pakistan

Plant growth promoting rhizobacteria (PGPR) mediate the soil processes such as decomposition, nutrient mobilization, mineralization, solubilization, nitrogen fixation and growth hormone production. Microorganisms having the phosphate solubilizing capacity can convert the insoluble phosphates into soluble forms through the production of organic acids. Inoculation of seed with P-solubilizing microorganisms is a promising technique which may alleviate the deficiency of phosphorus. This bioavailability of soil inorganic phosphorus in the rhizosphere varies considerably with plant species and nutritional status of soil. A field experiment was conducted at Fiber Crops Section, Ayub Agricultural Research Institute (AARI) Faisalabad to assess the ability of P-solubilizing rhizobacteria to enhance the growth and yield of cotton. Isolation and screening of P-solubilizer on Pikovskaya’s medium was carried out at the Soil Bacteriology Section Faisalabad. The trial was conducted on clay loam soil with pH 8.3, EC 2.8 dSm, N 0.040 %, organic matter 0.75% and available P 10.3 mg kg with three fertilizer levels viz. 120-30, 120-60, 120-90 kg NP ha with and without P-solubilizer (Bacillus sp.) inoculum. Results revealed that bacterial inoculum produced significantly higher seed cotton yield 1630 as compared to 1511 kg ha. The highest seed cotton yield was observed at highest fertilizer level i.e. 1733 kg ha with inoculum. The physical parameters like plant height, number of bolls per plant and boll weight and soil available P determined at regular intervals (30, 60, 90, days after sowing) was also found higher in the inoculated treatments. More exploration of this area of research should be carried out in different ecologies to compensate the mineral fertilizers

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Role of phosphate solubilizing bacteria (PSB) in enhancing P availability and promoting cotton growth.

A study was conducted at Cotton Research Station, Multan during 1999-2000 and 2000-2001 to examine the effect of PGPR inoculation alone and in combination with three levels of mineral nitrogen fertilizer (0-56-60, 56-56-60 and 112-56-60 kg NPK/ha) on cotton (cv. MNH-552). The bacterial inoculum (50 g / kg of seed) significantly increased seed cotton yield (21%), plant height (5%) and microbial population in soil (41 %) over their respective controls while boll weight, GOT and staple length remained statistically unaffected. Further field studies are needed to investigate the role of PGPR in improving the yield of non- legumes.

Response of cotton to plant growth promoting rhizobacteria (PGPR) inoculation under different levels of nitrogen

Training and development are continuous process in improving the caliber of employees. It is an attempt to improve their current and future performance but the organization should keep a track on their performance after imparting them training it means training needs assessment it is a systematic process of altering the behavior of employees in a direction to achieve the organization's goals. A training program is an effort by the employer to provide opportunities for the employees to acquire job interrelated skills, attitudes and information. In order to meet the ever-growing needs of education the sector has to become dynamic and updated in modern scenario and also to take up this sector to the heights of international excellence requires best combination of new technology and skillful and talented manpower In this research paper an attempt is made to learn that training and development exist in education sector and their impact to generate efficiency of employees to cater to the need of their customers.

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Anam Iqbal

Papers

The relationship between corporate social responsibility, job satisfaction, and organizational commitment: Case of Pakistani higher education

Service quality and customer satisfaction in the banking sector: a comparative study of conventional and Islamic banks in Pakistan

Role of phosphate solubilizing bacteria (PSB) in enhancing P availability and promoting cotton growth.

Response of cotton to plant growth promoting rhizobacteria (PGPR) inoculation under different levels of nitrogen

The Impact of Employees Training On the Job Performance in Education Sector of Pakistan