In materials engineering, it is often essential to know what are the best solvents to process any polymer, and employing methods based on Hansen solubility parameters are an effective way to find them. In this work the Hansen solubility parameters of polyether sulfone, lignin, and bitumen have been calculated by an alternative optimization procedure. It has been shown that, by applying an evolutionary strategy to Hansen's correlation method, it is possible to improve the fitting of solubility spheres. Compared with previous calculations, most quality‐of‐fit parameters are optimized. As a result, the sphere radii are reduced and, except for lignin, at least one of the solubility parameters is considerably changed (by 0.9–1.5 MPa1/2). Shortcomings of the correlation method are also pointed out, such as lack of data quality evaluation on set of solvents and uncertain character for partially solving solvents. At least the former could be handled by a proposed parameter called fill factor. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39696.

Seed inoculation with plant growth promoting rhizobacteria (PGPR) is an ideal tool to supply the soil with a high density of beneficial microorganisms. However, maintaining viable microorganisms is a major problem during seed treatment and storage. In this work, an evaluation was made of the effect of bacterial immobilization in nanofibers on the stability (viability and maintenance of beneficial properties) of two potential PGPR, Pantoea agglomerans ISIB55 and Burkholderia caribensis ISIB40. Moreover, the impact of soybean seed coating with nanofiber-immobilized rhizobacteria on bacterial survival during seed storage and on germination and plant growth parameters was determined. Bacterial nanoimmobilization and subsequent seed coating with nanofiber-immobilized rhizobacteria were carried out by electrospinning. The results demonstrate that this technique successfully immobilized P. agglomerans ISIB55 and B. caribensis ISIB40 because it did not affect the viability or beneficial properties of either rhizobacteria. Seed coating with nanofiber-immobilized rhizobacteria improved P. agglomerans ISIB55 and B. caribensis ISIB40 survival on seeds stored for 30 days and contributed to the successful colonization of both bacteria on the plant root. Moreover, seed coating with P. agglomerans ISIB55 increased germination, length and dry weight of the root. Furthermore, seed coating with B. caribensis ISIB40 increased leaf number and dry weight of the shoot. Therefore, the technique applied in the present work to coat seeds with nanofiber-immobilized PGPR could be considered a promising eco-friendly approach to improve soybean production using a microbial inoculant.

The electrospinning technique of rhizobia immobilization in nanofibres is an innovative and promising alternative for reducing the harmful effects of environmental stress on bacteria strains in a possible inoculant nanotechnology product for use in agriculture. The use of polyvinyl alcohol (PVA) shows up as an effective polymer in cell encapsulation because of its physical characteristics, such as viscosity and power of scattering. The aim of these studies has been to evaluate the survival of rhizobia incorporated in PVA nanofibres, which were applied to soybean seed and then subjected to different storage times and exposure to fungicide. The maintenance of the symbiotic characteristics of the incorporated bacterial strains was also evaluated, noting the formation of nodules in the soybean seedlings. No significant differences in the cell survival at 0 h and after 24 h of storage were observed. After 48 h, a significant difference in the bacterial cell concentration of the seeds affixed with PVA nanofibres was observed. Exposure to the fungicide decreased the viability of the bacteria strains even when coated with the nanofibres. A larger number of nodules formed in soybean seedlings from seeds inoculated with rhizobia incorporated in PVA nanofibres than from seeds inoculated with rhizobia without PVA. Thus, the electrospinning technique is a great alternative to the usual protector inoculants because of its unprecedented capacity to control the release of bacteria.

Seed treatments are chemical or biological substances that are applied to seeds to control infection by disease-causing organisms, insects, or other pests. Seed treatment reduces production costs of seedlings, reduces the consumption of seeds, facilitates mechanization of sowing and improves the seedling establishment. The generation of nanofibres and microcapsules by the electrospinning technique is a novel approach for active ingredient controlled release. The study evaluates an innovative rice seed coating (Oryza sativa) with polymer nanofibres and microparticles using this method. Materials and Methods: Polymer nanofibres and microcapsules were applied by the electrospinning technique to irrigated rice seeds. The treatments consisted of: 1) Control, 2) Negative control-Polymer based microcapsule without fungicide. 3) Polymer based microcapsule with fungicide. Microbiological assays and germination tests were performed following the guidelines of the Seed Analysis Rules of the Ministry of Agriculture. Results: The applied polymer as a coating did not affect the physiological quality of the seeds, as attested by the result of the germination tests, and they proved to be effective in the control of fungi disease in crop seeds. Conclusion: The germination and phytosanitary characteristics were improved in the analyzed study.

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