Zakorovljenost kukuruza u ekstenzivnom, konvencionalnom i održivom sistemu gajenja

Industrijalizovana poljoprivreda je donela brojne ekološke probleme, vođena zahtevima za većom produktivnošću. Zbog toga je gajenje useva uz smanjenu upotrebu pesticida, u sistemima koji prate klimatske promene, predmet novih regulativa koje zahtevaju pronalaženje balansa između produktivnosti i osnovnih principa održivosti kao što je očuvanje biodiverziteta. Prema Evropskom zelenom dogovoru (2021) potrebno je smanjiti upotrebu pesticida za 50% do 2030. godine. U održivim sistemima gajenja useva prioritet je smanjiti upotrebu pesticida i povećati efikasnost proizvodnje uz iskorišćavanje postojećih resursa i zaštitu agroekosistema. Jedan od načina povećanja održivosti jeste gajenje kukuruza nakon pokrovnih useva koji doprinose unapređenju kvaliteta zemljišta, čuvaju rezerve vode, smanjuju zakorovljenost i pojavu štetočina i bolesti. Cilj istraživanja je da se ispita kako alternativni sistemi gajenja utiču na prinos i zakorovljenost kukuruza, pa će u tom smislu istraživanja biti višegodišnja. U 2020. godini je u Institutu za kukuruz „Zemun Polje“, Beograd, započet ogled sa proučavanjem tri sistema gajenja kukuruza i njihovog uticaja na zastupljenost korova: - ekstenzivni sistem: posle žetve strnina (oz. pšenica), površina ostaje neobrađena, žetveni ostaci se ne zaoravaju, tokom leta se primenjuje totalni herbicid radi suzbijanja izniklih korova, u proleće se direktnom setvom poseje kukuruz; - intenzivni sistem: posle žetve strnina (oz. pšenica), strnište se plitko zaorava (ljuštenje strništa), kasnije se suzbijaju iznikli korovi primenom totalnog herbicida, u jesen se sprovodi duboko oranje, u proleće predsetvena priprema zemljišta i setva kukuruza; -održivi sistem: posle žetve strnina (oz. pšenica), strnište se plitko zaorava (ljuštenje strništa), seju se ozimi pokrovni usevi – ozimi ovas, ozimi stočni kelj i ozimi stočni grašak, pokrovni usevi se u proleće pokose i kada biomasa svene i delom se razgradi, direktnom setvom seje se kukuruz. U sva tri sistema gajenja kukuruza, korovi su ocenjeni nakon primene svih opisanih mera, a pre primene herbicida, 3.6.2021., metodom probnih kvadrata. Utvrđen je broj vrsta, broj jedinki, sveža i suva masa korova po m2. Najveća zakorovljenost utvrđena je u konvencionalnom sistemu gajenja kukuruza - 15 vrsta, 109 jedinki, 1712,1 g sveže i 1166,8 g suve mase korova po m2. U ovom sistemu gajenja, najzastupljenije su bile vrste Chenopodium album (L.), Amaranthus retroflexus (L.) i Bilderdykia convolvulus (L.). U ekstenzivnom sistemu gajenja kukuruza je bilo 7 vrsta korova čiji je broj jedinki bio 28 jed. m-2 a sveža i suva masa 152,4 i 142,4 g m-2. Pretpostavlja se da su žetveni ostaci pšenice delovali kao mrtvi malč i sprečili klijanje i nicanje korova u većoj meri. Najmanju zakorovljenost imao je održivi sistem gajenja kukuruza i to varijante sa stočnim keljom i stočnim graškom kao pokrovnim usevima koje su imale 4 i 3 vrste korova i to Convolvulus arvensis (L.), Sorghum halepense (L.) Pers., Digitaria sanguinalis (L.) Scop. i Hibiscus trionum (L.). Navedene vrste korova su produkovale po 15 jedinki korova po m2 na svakoj varijanti dok je sveža masa korova iznosila 52,5 i 22,5 g m-2 a suva 31,6 i 14,0 g m-2. Dobijeni jednogodišnji rezultati nisu dovoljni za izvođenje suštinskih zaključaka pa će se istraživanja nastaviti. Ipak, evidentno je da alternativni sistemi proizvodnje kukuruza imaju perspektivu i prednosti u pogledu zakorovljenosti useva kukuruza

The Pharmacokinetics of Recombinant Human Erythropoietin in Balkan Endemic Nephropathy Patients

Background: Balkan endemic nephropathy (BEN) hemodialysis patients require a higher dose of recombinant human erythropoietin for maintaining target hemoglobin level than patients with other kidney diseases. Objectives: Comparison of the pharmacokinetics of beta-erythropoietin given subcutaneously to hemodialysis patients with BEN or other kidney diseases (non-BEN). Methods: Recombinant human erythropoietin (75U/kg) was administered subcutaneously to 10 BEN and 14 non-BEN hemodialysis patients. The predose plasma level of erythropoietin (Epo) was subtracted from all postdose levels. The relevant pharmacokinetic parameters were calculated after noncompartmental pharmacokinetic analysis using Kinetica software (Thermo Scientific, ver.5.0). Results: Although basal plasma Epo concentration was similar in BEN (20.1 +/- 10.3U/L) and non-BEN (15.1 +/- 8.1U/L; p=.1964) patients, there were significant differences between the groups for elimination rate constant (0.016 +/- 0.006 vs 0.026 +/- 0.011 hr(-1); p=.020) and elimination half-life (50.24 +/- 19.12 vs 33.79 +/- 18.91 hr, p=.048). These differences remained significant after adjustment for patient characteristics (age, sex, hennodialysis duration, ferritin, PTH and ACEI use). No significant differences between groups were found in maximal Epo concentration, time to maximum Epo concentration, area under the curve from time of dosing extrapolated to infinity, clearance, mean residence time of Epo between groups both before and after adjustment. Conclusion: Pharmacokinetic analysis of beta-erythropoietin detected a significantly longer elimination half-life in BEN than in non BEN patients. This finding needs to be confirmed in a well-controlled study with a larger sample size

Valdecoxib stability properties under forced degradation conditions

The present work describes forced degradation study of valdecoxib, under different ICH recommended stress conditions - photolytic degradation, oxidation, hydrolysis in alkaline and acidic conditions as well as its thermal degradation. Stress studies were performed at valdecoxib drug substance and the final dosage form. Chromatographic separations of drug and the degradation products formed under various experimental conditions was successfully achieved on RP-18e Chromolith® performance monolithic column (100 mm × 4.6 mm, macropore size 2 μm, mesopore size 13 nm) with an eluent containing the mixture of methanol and water solution of TEA (1%, pH 7.4) in the ratio 40:60 (v/v) while the column temperature was adjusted to 30°C. Detection was performed using photodiode array detector on several wavelengths in order to ensure the proper insight into drug degradation pathway in case the formed products differ in absorption characteristics

Maize productivity in sustainable system of cultivation

Održivi sistemi gajenja useva su alternativa intenzivnoj, industrijalizovanoj poljoprivredi u kojoj je dudgogodišnja primena pesticida ugrozila životnu sredinu. U održivim sistemima gajenja, prioritet je smanjiti upotrebu herbicida i đubriva i povećati efikasnost proizvodnje uz korišćenje postojećih resursa radi zaštite agroekosistema. U tom smislu, pokrovni usevi i sistemi obrade zemljišta mogu doprineti značajnom smanjenju zakorovljenosti kukuruza, održanju kvaliteta zemljišta uz ostvarenje visokog i kvalitetnog prinosa. Istraživanja su sprovedena u Institutu za kukuruz Zemun Polje, Beograd, sa ciljem da se utvrdi koliki je doprinos održivog sistema gajenja (sa pokrovnim usevima) u poređenju sa konvencionalnim/intenzivnim sistemom gajenja, plodnosti zemljišta i produktivnosti kukuruza. Ogled je postavljen 2020. godine i čine ga tri sistema gajenja kukuruza:- ekstenzivni sistem: posle žetve strnine (oz. pšenica), zemljište je ostalo neobrađeno, krajem leta je primenjen totalni herbicid radi suzbijanja izniklih korova, u proleće je direktnom setvom posejan kukuruz - intenzivni sistem: posle žetve strnine (oz. pšenica), strnište je plitko zaorano (ljuštenje strništa), kasnije su primenom totalnog herbicida suzbijeni iznikli korovi, u jesen je zemljište duboko uzorano a u proleće je obavljena predsetvena priprema zemljišta frezom i setva kukuruza -održivi sitem: posle žetve strnine (oz. pšenica), strnište je plitko zaorano (ljuštenje strništa) nakon čega su posejani ozimi pokrovni usevi – ozimi ovas, ozimi stočni kelj i ozimi stočni grašak; pokrovni usevi su u proleće pokošeni i kada je biomasa svela i delom se razgradila, direktnom setvom je posejan kukuruz.Setva visokorodnog hibrida kukuruza najnovije generacije, ZP5601 je obavljena 6. maja 2021. u gustini od 60 606 biljka po ha. U navedenim sistemima gajenja kukuruza analiziran je sadržaj ukupnog N i C, kao i odnos C:N iz uzoraka zemljišta uzetih pre setve kukuruza kao i prinos kukuruza, obračunat na 14% vlage u zrnu. Na početku vegetacione sezone 2021. godine, najveći sadržaj organskog C je imala varijanta sa konvencionalnim sistemom gajenja, najveći sadržaj ukupnog N je utvrđen takođe u ovoj i varijanti sa ekstenzivnim sistemom gajenja, dok su najpovoljniji odnos C:N imale varijante sa pokrovnim usevima od ozimog stočnog kelja i stočnog graška. Na kraju vegetacionog perioda u promenljivoj i, za kukuruz, nepovoljnoj 2021. godini, najveći prinos je imao ekstenzivni sistem gajenja (6,70 t ha-1) a nešto niži konvencionalni sistem (6,38 t ha-1) dok je od pokrovnih useva najproduktivnije bilo gajenje kukuruza nakon stočnog graška (5,61 t ha-1).Sistemi gajenja kukuruza, posebno kada se radi o proizvodnji za ljudsku ishranu, će ubuduće sve više težiti održivosti i upotrebi alternativnih mera kad je u pitanju upotreba pesticida.Sustainable systems of crop cultivation are an alternative to intensive, industrialised agriculture in which a long-term application of pesticides has endangered the environment. The priority in these systems is to reduce the use of herbicides and fertilisers and to increase the production efficiency while using existing resources to protect agro-ecosystems. In this sense, cover crops and tillage systems can contribute to a significant reduction in maize weediness, maintenance of soil quality while achieving high and quality yields. Studies were conducted at the Maize Research Institute, Zemun Polje, Belgrade, with the aim to determine the contribution of the sustainable cultivation system (with cover crops) in comparison to the conventional/intensive cultivation system, soil fertility and maize productivity. The trial was set up in 2020 and encompassed three maize growing systems:- extensive system: after stubble (winter wheat) harvest, soil remained untilled and at the end of summer a total herbicide was applied to control emerged weeds, while in spring, maize was sown by direct sowing - intensive system: after stubble (winter wheat) harvest, stubble was shallowly ploughed (shallow ploughing), later the total herbicide was applied to suppress emerged weeds; in autumn, soil was deeply ploughed up, while seedbed preparation with a cultivator and maize sowing were done in spring -sustainable system: after stubble (winter wheat) harvest, stubble was shallowly ploughed (shallow ploughing) and then winter cover crops (winter oats, winter fodder kale and winter field pea) were sown; cover crops were mowed in spring and when biomass was wilted and partially decomposed, maize was sown by direct sowing. Sowing of a high-yielding maize hybrid of the latest generation, ZP5601, was performed on May 6, 2021 at the sowing density of 60,606 plants ha-1. In the stated maize cultivation systems, the contents of total N and C, as well as the C:N ratio were analysed in soil samples drawn prior to maize sowing and maize yield was calculated at 14% grain moisture. At the beginning of the 2021 growing season, the highest content of organic C was recorded in the variant with the conventional cultivation system, whereas the highest content of total N was also determined in this variant but with the extensive cultivation system; the most favourable the C:N ratio was established in variants with cover crops consisted of winter fodder kale and field pea. At the end of the 2021 growing season that was variable and unfavourable for maize, the highest yield (6.70 t ha-1) was recorded in the extensive cultivation system; a slightly lower yield (6.38 t ha-1) was achieved in the conventional system, while the most productive (5.61 t ha-1) in the cover crop system was maize cultivation after field pea. Maize cultivation systems, especially when it comes to the production for human consumption, will increasingly tend to sustainability and the use of alternative measures instead of the pesticide application

The position of the Chinese massage (Tuina) in clinical medicine

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Thermal diffusivity and electron transport properties of NTC samples obtained by the photoacoustic method

Thermal diffusivity and electron transport parameters of sintered NTC samples were determined by the photoacoustic (PA) technique. Powder mixtures composed of MnO, NiO, CoO and Fe2O3 were milled to nanometer particle size. NTC discs were dry powder pressed and sintered at different temperatures in the range from 900 degrees C to 1300 degrees C for 30 min. A second group of NTC discs was sintered at 1200 degrees C with the sintering time varying from 30 min to 360 min. These NTC samples were polished and exposed to a chopped laser beam in order to plot a response in the acoustic range. The thermal diffusivity of sintered NTC layers based on a metal oxide powder mixture was measured at room temperature by the photoacoustic technique. An increase of thermal diffusivity with the sintering temperature and time of sintering was observed

Investigation of Balkan endemic nephropathy in Serbia: How to proceed?

Balkan endemic nephropathy (BEN) presents an unsolved puzzle despite fifty years of its investigation. Academy of Medical Sciences of the Serbian Medical Society organized a round table discussion on current unsolved problems related to BEN. The present paper summarizes presentations, discussion and conclusions of this meeting. During the last fifty years, the course of BEN prolonged and it shifted towards the older age in all endemic foci. Data on the incidence of BEN have been controversial and frequently based on the data on the number of BEN patients starting haemodialysis treatment. In Serbia, BEN patients present 6.5% of haemodialysis population and this percentage differs among different centres ranging from 5% (Leskovac) to 46% (Lazarevac). Maintenance of high prevalence of BEN patients on regular haemodialysis indicates that BEN is not an expiring disease. In addition, recent data have shown more frequent microalbuminuria and low-molecular weight proteinuria in children from endemic than from nonendemic families. Aetiology of BEN is still unknown despite numerous investigations of environmental and genetic factors. Today, there is a very current hypothesis on the aetiological role of aristolochic acid but the role of viruses, geochemical factors and genetic factors must not be neglected. Morphological features of BEN are nonspecific and characterized by acellular interstitial fibrosis, tubular atrophy and changes on preand postglomerular vessels. New immunohistochemical and molecular biology methods offer a new approach to BEN investigation. Association of BEN with high incidence of upperurothelial tumours is well-known. Recent studies have shown significant changes of demographic characteristics of patients suffering upper-urothelial tumours, their prevalence in different endemic foci and characteristics of tumours. Further studies of BEN should be directed to determination of incidence and prevalence of disease in different endemic foci, investigations of different insufficiently examined aetiological factors as well as pathomorphological features of the disease by the use of modern methods