No abstract

Highly specific and sensitive, the proposed fluorometric method for determining α-tocopherol is robust and fairly fast. Ithas been tested in parallel with a conventional thin layer chromatographic method on foods and feeds. The only necessarycleanup is the usual saponification. The unsaponificable fraction can be extracted with ethyl ether or, preferably, withExtrelut columns. Reagents and their solvents are added to the isooctane solution before each successive reaction and arethen eliminated by partition with water. The α-tocopherol (α-T) derivative always remains in isooctane. The first step isnitrosation and elimination of tocopherols and tocotrienols other than α-isomers. α-T is then oxidized to α-tocored (α-TR)with a mixture of sulfuric acid, ferric chloride, and iodine bromide. Α-TR is then condensed to a new reagent: 4,5-dimethylo-phenylenediamine. The phenazine formed is strongly fluorescent. Iodine and bromine add to the double bonds of α-tocotrienol present and quench the fluorescence of its phenazine.

No abstract

The paper is based on the researches carried out during 1976-2010 in the long term trial placed on the prelvosoil from Agricultural Research and Development Station Oradea. The main field crops of the area (wheat, maize, sunflower, soybean, bean, potato, sugarbeet, alfalfa) were studied. Based on the soil moisture determination ten to ten days, the soil water reserve was maintained between easily available water content and field capacity on the watering depth. Pedological and strong pedological drought (the decrease of the soil water reserve on watering depth bellow easily available water content, bellow wilting point respectivelly) were registered every year. The use of the irrigation determined the improve of the water/temperature+light (Domuta climate index) report, the increase of the daily and total water consumption, yield gains very significant statistically, the improve of the yields stability and yields quality, the increase of the water use efficiency. The use of the good soil management didn’t worsen the soil structure and the chemical  and biological parameters of the soil were improved. The researches sustain the irrigation opportunity for sustainable agriculture in the North-Western Romania.

The paper is based on the researches carried out in the long term trial placed on the preluvosoil from Oradea in 1976, for establishingthe soil water balance. In the irrigated variant the soil moisture was determined 10 to 10 days for maintaining the soil water reserve onirrigation depth (0 – 50 cm for wheat and bean, 0 – 75cm for maize, sunflower, soybean, sugarbeet, potato and alfalfa 1st year and 0 – 100cm for alfalfa 2nd year) between easily available water content and field capacity. Thus, an average irrigation rate of 2560 m³/ha was usedin the 9 experimental crops. The average of the annual rainfall for the 1976 – 2008 period was of 625.0 mm. The technologies used werecorrelated with the needes of the crops, such as melioration crop rotation, chemical fertilizers in accordance with the chemical export on theyield, manure (40 t/ha) was used in potato and sugarbeet. After 33 years of the irrigation use the soil structure degree (38.62%) did notdecrease when compared to the unirrigated maize – wheat crop rotation (37.01%). Bulk density, total porosity, penetration resistance andhydraulic conductivity have worse values than the ones in the unirrigated variant. The humus content is very close to the humus contentdetermined in 1976, the phosphorus and the potassium content increased very much in comparison with the initial content (117 ppm vs 22.0ppm); (180.0 ppm vs 102 ppm). The use of the adequate fertilization system and of the irrigation water with a good qaulity did not determinea decrease of the pH value of the soil. The irrigation determined the improve of the microclimate conditions, the increase of the plant waterconsumption, yield gains very significant statistically and higher protein content of the maize grains.