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.
Effect of Azospirillum brasilense inoculation on growth dynamics and hydraulic conductivity of sorghum bicolor roots
Abstract Root growth was monitored in hydroponic systems under greenhouse conditions. Inoculation with Azospirillum brasilense increased the total number and length of adventitious roots of Sorghum bicolor by 33–40% over non‐inoculated controls. This resulted from a higher rate of growth, earlier root appearance and a greater elongation rate of individual sorghum roots. Inoculation also led to a 25–40% increase in hydraulic conductivity of the inoculated root system as compared to controls. In plants subjected to an osmotic stress by the addition of polyethylene glycol (PEG 6000) to the growth medium to produce an osmotic potential of ‐2.0 bar, inoculation significantly diminished most of the drastic adverse effects on root growth. It was concluded that beneficial effects of Azospirillum on the growth and yield of sorghum can be attributed largely to improved growth and function of the root system.
Production of a potentially novel anti-microbial substance by Bacillus polymyxa
A bacterial strain, SCE2, identified as Bacillus polymyxa, produced an anti-microbial substance active against yeasts, fungi and different genera of Gram-positive and-negative bacteria, in liquid medium and in plate assays. This substance appeared to be an antibiotic different from the polymyxin group, mainly because of its action against the majority of Gram-positive bacteria tested and its lack of activity against Pseudomonas aeruginosa, a species usually killed by polymyxins. Preliminary characterization showed resistance to heat (65°C, 2 h), to proteases, trypsin, lysozyme, deoxyribonuclease I, ribonuclease A, phospholipase C, ethanol, acetone, chloroform, ether and to strong alkali treatment (2 M NaOH). The molecular weight was less than 3500. The B. polymyxa strain harboured a plasmid that did not correlate with antibiotic production; after curing experiments, a derivative strain, SCE2(46), was isolated that lacked the plasmid pES1, but showed the same inhibitory spectrum as the wild-type strain.