Kostova D.,Agricultural University of Plovdiv
Journal of Analytical Chemistry | Year: 2014
The optimum conditions for extraction of microquantities of chromium(VI) as an ion-association complex with blue tetrazolium chloride (BTC) and tetranitrotetrazolium blue chloride (TNBT) has been determined. The extracted species was a 1: 2 of the BTC and TNBT cation and the chlorochromate anion. Beer’s law was obeyed in the range of 0.04–0.8 μg/mL Cr(VI) for BTC and 0.1–1.6 μg/mL Cr(VI) for TNBT. The molar absorptivities were ɛ255 = 7.77 × 104 L/(mol cm) (for BTC) and ɛ275 = 2.04 × 104 L/(mol cm) (for TNBT). Sandell’s sensitivity of the systems were found to be 6.69 × 10−4 μg/cm2 (for BTC) and 2.55 × 10−3 μg/cm2 (for TNBT). Limit of detection (LOD) is 8.55 ng/mL and limit of quantitation (LOQ) is 0.028 μg/mL Cr(VI) for BTC. For TNBT, LOD is 0.031 μg/mL and LOQ is 0.103 μg/mL. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase have been determined. A sensitive method for determination of trace of chromium(VI) in plants has been developed. © 2014, Pleiades Publishing, Ltd.
Aladjadjiyan A.,Agricultural University of Plovdiv
International Agrophysics | Year: 2010
The paper describes the investigation of magnetic field treatment on the development of lentil seeds. Stationary magnetic field has been used. The germination energy and germination, length of stems and roots, measured on the 7th and 14th day, as well as the total mass have been used in order to evaluate the effect of magnetic field treatment. The germination energy and germination of seeds have not shown significant differences between variants. The length of stems and roots, measured on the 7th and 14th day, as well as the total mass have shown dependence from the dose of treatment, better expressed for the parameters measured on the 14th day. © 2010 Institute of Agrophysics, Polish Academy of Sciences.
Todorova S.,Agricultural University of Plovdiv
Journal of Central European Agriculture | Year: 2016
The agricultural sectors of the former centrally planned economies, including Bulgaria were in a state of economic crises in the period after socialist governments fell. The former system disappeared almost overnight while new market structures had not yet emerged. The outcome of this transition shocks was a sharp decline in both agricultural output and the sector's GDP in the early 1990s. Some countries of the Central and Eastern Europe (CEE) recovered from this initial decline much faster. The principle reason for the difference appears to be the more resolute adherence of CEE governments to reform policies throughout their economies. The purpose of this study is to get more knowledge about the structure and possibilities of Bulgarian agriculture after the transition period and last but not least, about the effects of the EU CAP on the Bulgarian economy and farmers. That is why were made some interviews, and besides, it was carried out a questionnaire survey in order to get a picture about how farmers act in a new environment called the Common Agricultural Policy of EU. For collecting information, as well as confirming or rejecting the investigation hypotheses chi-square analysis was applied. © 2016, University of Zagreb - Faculty of Agriculture. All rights reserved.
Zlatev Z.,Agricultural University of Plovdiv |
Lidon F.C.,New University of Lisbon
Emirates Journal of Food and Agriculture | Year: 2012
At a whole plant level the effects of drought is usually perceived as a decrease in growth and photosynthetic carbon assimilation. That is why this review is focused mainly on recent information about the effects of drought on plant growth, water relations and photosynthesis, as well as mechanisms of adaptation. It is shown that plants have evolved a great number of adaptive mechanisms that allow the biochemical systems to cope with increased water deficit. The literature analyzed in this review shows the complexity of tolerance to water deficit and supports the statements of many authors that the flexibility of cell metabolism and its fast acclimation to changes in environmental conditions is a first essential step in stress avoidance.
Yanchev I.,Agricultural University of Plovdiv
Journal of Environmental Protection and Ecology | Year: 2014
The purpose of the present study was to find out the productivity and quality of new cultivars of common wheat grown in two ecological regions and originating from DZI - General Toshevo, owned by the Agronom company. The experiment was carried out on the training and experimental fields of the Department of Crop Science at the Agricultural University - Plovdiv and on the experimental field of the Agronom Company in the town of Dobrich. The basic meteorological factors affecting the quality and productivity of common wheat were analysed. The cultivars Vyara, Factor and Laska, included in the study, were grown after sunflower as preceding crop, applying the standard technology adopted in the country. The following characteristics were determined: test weight (kg), 1000-grain weight (g), wet gluten yield, crude protein in the dry matter, sedimentation number and grain yield in kg/ha. The results showed higher productivity of the cultivars under the conditions of the town of Dobrich, while the quality characteristics varied depending both on the region and the cultivar. The Vyara cultivar showed the highest productivity, followed by Laska and Factor.
Petrov S.,Agricultural University of Plovdiv
Biologia (Poland) | Year: 2013
Identification key of 20 species of the genus Trissolcus registered in Bulgaria is given. Three species, T. fuscus sp. n., T. simplex sp. n. and T. nigricans sp. n. are described as new for science. © 2013 Versita Warsaw and Springer-Verlag Wien.
Kostova D.,Agricultural University of Plovdiv
Journal of Analytical Chemistry | Year: 2011
Solvent extraction of molybdenum(VI) ion associate with triphenyltetrazolium chloride (TTC) has been studied. TTC was proposed as reagent for the spectrophotometric determination of micro amounts of molybdenum(VI) at λmax 250 nm. The optimum conditions for extraction of molybdenum(VI) as an ionassociation complex with TTC has been determined. Beer's law is obeyed in the range of 0.5-10 μg/mL molybdenum(VI). The molar absorptivity of the ion-pair is 1 × 106 L/mol cm. The sensitivity of the method is 9.6 × 10-5 μg/cm 2. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: distribution constant K D = 32.64, extraction constant K ex = 2.19 × 1010 association constant β = 6.71 × 108. The interferences of different cations, anions on molybdenum(VI) determination were also investigated. A sensitive and selective method for the determination of microquantities of molybdenum(VI) has been developed. The determination was carried out without preliminary separation of molybdenum. A novel procedure of molybdenum(VI) extraction and spectrophotometric determination in different plant samples was examined. © Pleiades Publishing, Ltd., 2011.
Nakova M.,Agricultural University of Plovdiv
European Journal of Plant Pathology | Year: 2010
Disease on fruit trees in Bulgaria caused by Phytopthora cactorum and P. citrophthora was found in the period 1998-1999. Leaves of some trees become reddish during July, and later in the season fall off. Infected trees die during the same season, or the next season. Observations on symptom development and spread of Phytophthora root and crown rot of fruit trees was undertaken from 1999 to 2009. Disease incidence is between 2% and 14% in some gardens and nurseries. The disease was registered in the regions of Plovdiv, Kjustendil, Sliven, Yambol, Karnobat, Bourgas and Svishtov. Samples from infected plant tissues were taken and isolations were done on selective PARP media, or by applying a baiting bioassay. Based on morphological and cultural characteristics and temperature requirements the following Phytophthora species have been identified: Phytophthora cactorum, P. citrophthora, P. drechsleri, P. cryptogea, hybrid and Pythium. Pathogenicity of the isolates was tested on green apple fruits or one-year-old apple rootstocks. Laboratory studies of the effect of temperature on mycelia growth showed that most isolates can grow from 5° up to 30°C, with an optimum from 18° to 25°C. Only three strains grew at 35-36°C, two developed slowly, one grew well. The optimal pH for mycelia development was tested. Aiming at control of disease, in vivo pot trials have been carried out for studying resistance of rootstocks to P. cactorum. At the end of the growing season a good level of resistance has been shown in the rootstocks M29C, Gizela 6, and MAXMA 14. © 2010 KNPV.
Ivanov K.I.,Agricultural University of Plovdiv |
Dimitrov D.Y.,Agricultural University of Plovdiv
Catalysis Today | Year: 2010
The oxidation of methanol on iron-molybdenum catalysts was investigated with view of gathering information about catalyst deactivation at temperatures in the catalyst bed lower than 300 °C. A 15 months' industrial experiment was carried out and samples of spent catalyst discharged step by step from the reactors were characterized by Mössbauer spectrometry, XRD, chemical analysis and surface area measuring. Catalytic measurements were also performed using a pseudo-isothermal reactor under conditions close to the industrial experiment. The results obtained demonstrate that, although slower, the process of deactivation of the industrial catalyst takes place even at temperatures lower than 300 °C. We reached the conclusion that the main reason for this is the removal of a part of the MoO3 and the decreasing of the specific surface. It was established that the formation of FeMoO4 and Fe2O3 is negligible and does not represent a dominant factor influencing the catalytic properties of the Fe-Mo catalyst under these conditions of industrial exploitation. © 2010 Elsevier B.V. All rights reserved.
Koumanov K.S.,Agricultural University of Plovdiv
Scientia Horticulturae | Year: 2015
This short communication brings to the attention of the scientific community a new hypothesis about the mechanism of the sweet cherry fruit cracking, which is a problem in most producing areas of the world and causes significant economic losses. It is commonly accepted that fruit crack after rainfalls because of the fruit-flesh swelling due to osmotic imbibition of water by cells. The proposed hypothesis attributes this phenomenon to fruit skin shrinking after its rapid cooling, caused by a rainfall or by sharp drop of the ambient temperature. If the proposed mechanism is correct, the cracking prevention measures should be thoroughly revised. Paradoxically, the expensive rain-preventing covers may be replaced by cheaper systems for cooling overhead (micro)sprinkling, which to be operated in the days with an unfavorable forecast. All related chemical treatments would not make sense anymore as well. © 2015 Elsevier B.V.