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  • Author or Editor: I. Ivanova x
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Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important pest of maize in the US. Six years ago, in 1992, this pest was first detected in Yugoslavia (Baca, 1993). In the period between 1992-1998, the distribution of WCR was observed in Hungary, Croatia, Bosnia and Herzegovina and Romania. In 1998, the first occurrence of WCR was recorded in Bulgaria.

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Abstract  

The possibilities of ED-XRF with241Am excitation source are evaluated in the analysis of geological materials: rocks, clays, soils, and sediments. The calibration curves are made using different SRM's. Data from the analysis of various SRM's are presented.

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Abstract  

A comparative evaluation of the applicability of different radionuclide sources for the determination of toxic elements in plants by ED-XRF is presented.238Pu or109Cd are suggested as most suitable single excitation sources in ED-XRF for monitoring investigations. More elements are determined with a combination of55F/109Cd(238Pu)/241Am. The results obtained by radionuclide ED-XRF analysis of different plants show that the method permits the reliable determination of Br, Ca, Fe, K, Mn, Rb, Sr and Zn in plant bioindicators. For toxic elements like As, Cd, Cu Cr, Hg, Ni, Se and Pb the detection limits of the method are not low enough.

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Abstract  

The conditions for the determination of Co, Cr, Fe, Mn, Ni and Pb in plant materials and As, Ba, Fe, Pb, Sr, Rb and Zr in soils by energy dispersive X-ray fluorescence analysis with americium-241 as excitation source are discussed. The applicability of the proposed method is tested by the analysis of certified reference materials and of two plant biomonitors.

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Abstract  

The usefulness of INAA, radionuclide ED-XRF, ICP-AES and AAS are comparatively evaluated for the determination of nutrients, essential and trace elements in various plant matrices. The comparison is performed by analysis of the following reference materials: NIST-SRM-1573, NIST-SRM-1575, NIES-1, NIES-3, NIES-6, IAEA-V-10 and Bowen's kale. The detection limits, accuracy and precision of the methods are discussed and a combination of INAA and GFAAS is recommended for analysis of plants for monitoring purposes.

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Seventy-three common winter wheat varieties developed throughout the breeding history of the DAI were investigated for their diversity of allelic variants on storage proteins component composition in grain. The high- and low molecular weight protein structures were determined by the widely used SDS-PAGE method of Payne et al. (1980). The ratio between the individual alleles on the loci of high and low molecular weight glutenin was analyzed. The change in the HMW-score was followed according to the period when the respective varieties were developed. The configuration Glu-A1 b , GluB1 c , Glu-D1 d , which was established in about 45% of the investigated genotypes, was most frequent in the high-molecular variants of glutenin. Concerning the low-molecular weight glutenins in 21 out of the 73 investigated varieties, the combination Glu-A3 c , Glu-B3 b , Glu-D3 c was observed; it coincided with the spectrum of the widely used variety Bezostaya 1. Highest diversity was established in the allelic variants of Glu-A3, Glu-B3 , in which 6 and 5 alleles, respectively, were observed. The quality of the varieties developed at DAI was relatively high (score 8.1). About a quarter of them are with high end-use quality confirmed in production. This is mainly due to the concentration of “strong” positive alleles in glutenin as a result from the intensive use of parents directly or indirectly related to Bezostaya 1, which lead to decrease of the percent of Glu-B1a (2 + 12). Quality should be further increased by additional diversity of combinations between “possitive” as effect on end-use grain quality alleles. Concerning HMW loci to keep of high grain end-use quality, it is necessary to maintain the status of Glu-A1b (2*), as well as of Glu-D1d (5 + 10).

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Seventy-six promising bread winter wheat lines were investigated in relation to the allelic composition of grain storage proteins. The aim of the study was: i) to find out a possible relation between wheat quality and the separate low molecular loci and ii) to examine the potential of some of the existing Glu-A3 alleles to increase the quality. Five indices were investigated that covered almost all aspects of grain quality: sedimentation value, wet gluten content, dough stability, bread volume, quality index and valorimeter. The samples for quality analysis were from a 3-year period of investigation. Different statistical approaches were used to study the influence of Glu-A3 on the level of the indices. The LMW-GS were determined by SDS-PAGE (Payne et al. 1980). It was determined that locus Glu-A3 had the strongest influence on quality among the loci, that determine the low molecular glutenins. The Glu-A3 alleles influenced the end-use quality irrespective of the HMW-GS and LMW-GS composition background against which their effect was expressed. There were important variations among the separate alleles of Glu-A3 locus for their direct effect on end-used quality. Glu-A3 f had strong positive effect on the end-use quality against the background of all HMW combinations. Glu-A3 b had a similar positive effect. The Glu-A3 b allele was connected with high quality in wheat but its effect was weaker than that of Glu-A3 f and was not significant for some of the investigated indices.

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Progress in Agricultural Engineering Sciences
Authors: G. Zsivanovits, Ts. Grancharova, I. Dimitrova-Dyulgerova, D. Ivanova, S. Kostadinova, and M. Marudova

The research presents the effect of novel edible coatings based on low molecular weight chitosan on some properties of fresh-cut melon fruits – weight loss, total soluble solids, total acidity, mechanical strength and bacteria growth. Three different compositions were used as coatings – pure chitosan, chitosan and Ca lactate and alginate/chitosan multilayers. It was shown that the additional alginate layer substantially improves the protective properties of pure chitosan coating, resulting in preservation of cell structure. Negligible negative effect on the antibacterial activity of pure chitosan is demonstrated.

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