The drying characteristics of Thompson seedless grape (vitis vinifera L.) were investigated using laboratory scale infra-red dryer at four levels of intensity of infra-red radiation (0.861, 0.973, 1.039 and 1.161 kW/m 2 ). The drier was also equipped with three axial flow fans to supply air with at three different temperatures (40, 50 and 60 o C) and constant velocity of 2 m/s over the samples to carry the evaporated moisture. The results showed that the moisture content of dried grapes was decreased from (287.15 ±1, %d.b.) to (19.83 -12.37, % db). It has been found that, both air temperature and infra-red radiation intensity affects rate of drying. Two drying models: Lewis model and Henderson and Pabis's model were examined. The models were compared using the statistical coefficients such as (R), (SE), (χ 2 ), (MBE) and (RMSE). Lewis's model was the best model for describing the drying curves of Thompson seedless grapes. A diffusion model was used to describe the moisture transfer and the effective diffusivity at each drying temperature and radiation intensity. The effective diffusivity ranged from (2.2393x10 -9 ) to (2.3033x10 −10 m 2 /s) and was significantly affected by radiation intensity. The average value of activation energy was (3.2051 kW/kg). The seedless Thompson grape dried at radiation intensity of (0.973 kW/m 2 ) and air temperature of (60 °C) recorded the highest quality of the dried samples in terms of, total soluble solid, total sugar, reducing sugars and remained Residual sulphur (SO2).
The present work was carried out to study the effect of four nitrogen fertilizer levels (40, 60 80 and 100 Kg. N./Feedan) on the infestation by beet fly, Pegomya mixta and sucking insects, Aphis gossypii, Bemisia tabaci and Empoasca lybica as well as sugarbeet yield during two successive seasons (2005/2006 and 2006/2007) in Mallawi, El-Minia Governorate. In both seasons, the highest rates of infestation by P. mixta larvae as well as nymphs and adults of A. gossypii, B. tabaci and E. lybica were obtained from fertilization with 100 Kg. N./Fed., whereas, the lowest infestation rates were recorded on sugarbeet plants fertilized by 40 Kg. N./Fed. The maximum root and sugar yields were obtained from sugarbeet plants received 80 Kg. N./Fed. The minimum root and sugar yields were produced from fertilization by 40 Kg. N./Fed. Fertilizer application at 80 Kg. N./Fed. could be useful in reducing the yield losses due to these insects and increase the root and sugar yields.
MATERIALS AND METHODSThe present study was carried out at the farm of the Agric. Res. Station, Mallawi District, El-Minia Governorate, during two seasons (2005/2006 and 2006/2007).An area of about one feddan was divided into 4 equal plots cultivated with Oscar poly sugarbeet variety on 15 th November of both seasons. The
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