No abstract

In this study, bacteria were isolated from the rhizosphere and inside the roots of canola (Brassica napus L.) plants grown in the field from northern Iran. Firstly, 150 strains (endophytic and rhizospheric isolates) isolated from canola were characterized for plant growth promoting (PGP) traits. Of them, one hundred isolates produced indole-3-acetic acid (IAA), whereas 17 isolates solubilized phosphate, 44 isolates produced siderophore, 34 produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase and five produced hydrocyanic acid (HCN). All of the screened isolates with different growth promoting traits were separately inoculated as different mixtures on two rice cultivars under gnotobiotic conditions. A total of 22 endophytic isolates were re-isolated from two rice cultivars and characterized for Plant Growth Promoting (PGP) traits again. All 22 endophytic isolates produced IAA. Secondly, the colonization and growth promoting effects of the IAA producing endophytic strains were compared in inoculated rice plantlets as single-strain inoculants. All of the IAA producing strains were consistently more active in colonizing rice seedlings as compared with other isolates. Therefore, it seems that IAA production may be required for endophytic competence as compared to other PGP traits in rice seedlings. In addition, this study indicates that the selected bacterial isolates based on their IAA producing trait have the potential for PGP and more colonization of rice.

No abstract

No abstract

A polyurethane (PU)-based powder coating reinforced with vinyltrimethoxysilane (VTMS)-functionalized ZrO 2 nanoparticles (V-ZrO 2 ) for thermal stability was developed. Chemical structure, microstructure and thermal degradation kinetics of the prepared coatings were investigated. The peak of aliphatic C-H vibrating bond in the Fourier transform infrared (FTIR) spectrum of V-ZrO 2 was a signature of VTMS attachment. Scanning electron microscopy (SEM) images reveled that, by increase of V-ZrO 2 content from 0.1 to 0.3 wt.% and then 0.5 wt.%, some agglomerations of nanoparticles are formed in the PU matrix. Thermogravimetric analysis (TGA) of the PU/V-ZrO 2 powder coatings was performed at different heating rates nonisothermally to capture alteration of activation energy (E a ) of degradation of PU/V-ZrO 2 powder coatings as a function of partial mass loss by using Friedman, Kissinger-Akahira-Sunose (KAS), Ozawa-Wall-Flynn (FWO) and modified Coats-Redfern isoconversional approaches. It was observed that by addition of 1 wt.% V-ZrO 2 to PU resin the early state degradation temperature at 5% weight loss increased about 65 • C, suggesting a physical barrier effect limiting the volatility of free radicals and decomposition products. Incorporation of 5 wt.% ZrO 2 led to about 16% and 10% increase in E a and LnA of blank PU, respectively, which was indicative of higher thermal resistance of nanocomposite powder coatings against thermal degradation. There was also obvious agreement between model outputs and experimental data. The results reveal that nanocomposite coating shows superior thermal properties compared to neat PU powder coatings, and the presence of nano ZrO 2 in sufficient amount causes retardation of the thermal decomposition process.