Effect of Plant Growth Promoting Rhizobacteria (PGPR) and Planting Pattern on Yield and Its Components of Rice (Oryza sativa L.) in Ilam Province, Iran
Abstract—Most parts of the world such as Iran are facing the excessive consumption of fertilizers, that are used to achieve high yield, but increase the cost of production of fertilizer and degradation of soil and water resources. This experiment was carried out to study the effect of PGPR and planting pattern on yield and yield components of rice (Oryza sativa L.) using split plot based on randomized complete block design with three replications in Ilam province, Iran. Bio-fertilizer including Azotobacter, Nitroxin and control treatment (without consumption) were designed as a main plot and planting pattern including 15 × 10, 15 × 15 and 15 × 20 and the number of plant in hill including 3, 4 and 5 plants in hill were considered as a sub-plots. The results showed that the effect of biofertilizers, planting pattern and the number of plants in hill were significant affect on yield and yield components. Interaction effect between bio-fertilizer and planting pattern had important difference on the number spikelet of panicle and harvest index. Interaction effect between bio-fertilizer and the number of plants in hill were significant affect on the number of spikelet per panicle. The maximum grain yield was obtained by inoculation with Nitroxin, planting pattern of 15 × 15 and 4 plants in hill with mean of 1110.6 g.m, 959.9 g.m and 928.4 g.m, respectively.
Potential for improving pea production by co-inoculation with fluorescent Pseudomonas and Rhizobium
Seed bacterization with five plant growth promoting fluorescent Pseudomonas strains isolated from Indian and Swedish soils and three Rhizobium leguminosarumbiovar viceae strains isolated from Swedish soils were shown to promote plant growth in Pisum sativum L. cv. Capella. Co-inoculation of the fluorescent pseudomonads and Rhizobium improved plant growth in terms of shoot height, root length and dry weight. Both the fluorescent pseudomonads and Rhizobium were shown to exhibit a wide range of antifungal activity against pathogens specific to pea. Seed bacterization with plant growth promoting strains alone and together with a rhizobial isolate, R 361-27 reduced the number of infected peas grown in Fusarium oxysporum infested soils. We found that the introduced organisms were able to colonize the roots, which was confirmed using immunofluorescence staining and drug resistant mutant strains. In a synthetic culture medium, all the plant growth promoting fluorescent pseudomonads strains produced siderophores, which shown to express antifungal and antibacterial activity. Our results suggest the potential use of these bacteria to induce plant growth and disease suppression in sustainable agriculture production systems.
Plant-growth-promoting rhizobacteria.
Several microbes promote plant growth, and many microbial products that stimulate plant growth have been marketed. In this review we restrict ourselves to bacteria that are derived from and exert this effect on the root. Such bacteria are generally designated as PGPR (plant-growth-promoting rhizobacteria). The beneficial effects of these rhizobacteria on plant growth can be direct or indirect. This review begins with describing the conditions under which bacteria live in the rhizosphere. To exert their beneficial effects, bacteria usually must colonize the root surface efficiently. Therefore, bacterial traits required for root colonization are subsequently described. Finally, several mechanisms by which microbes can act beneficially on plant growth are described. Examples of direct plant growth promotion that are discussed include (a) biofertilization, (b) stimulation of root growth, (c) rhizoremediation, and (d) plant stress control. Mechanisms of biological control by which rhizobacteria can promote plant growth indirectly, i.e., by reducing the level of disease, include antibiosis, induction of systemic resistance, and competition for nutrients and niches.