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Abstract This study was carried out at El-Raheb Experiment Farm, Faculty of Agriculture, Minufiya University, Shibin El-Kom, during the two successive seasons of 2006 and 2007. In the two experiments, a randomized complete block design with three replicates was used. We used two mineral fertilizers such as ammonium nitrate and ammonium nitrate + ammonium sulphate (1 : 1, w/w) and four biofertilizers namely Rhizobacterin, Nitrobein, Biogene and Microbein at a rate of 2 kg / fed. besides Farmyard Manure (FYM) and control (unfertilized). The results showed that, highly significant varietal differences were found among fertilizer treatments, where mineral fertilizers gave the highest yield of potato by increasing percentage of 124.28 and 100.35 in two growing seasons, respectively and a high marketable yield of potato had got by organic fertilizer FYM. Tuber grade (A) which weight over 100 g was observed by ammonium nitrate treatment, grade B (50 ± 100 g) by FYM. Reducing sugars decreased but non reducing sugars increased significantly. Starch content increased by FYM and biofertilizer and decreased by mineral fertilizers. Ash content increased significantly by both mineral fertilizers used, while the fibers content decreased significantly and this reduction was very high by application of Rhizobacterin. Dry matter increased by FYM and biofertilizers application but decreased by mineral fertilizers, where the highest dry matter was achieved by Nitrobein (25.75%) which gave the highest value of ascorbic acid (16.78 mg/100 g). High nitrate level was recorded by mineral fertilizers (340.26 mg/kg) and the lowest value (199.54 mg/kg) by FYM. High yield of pea by FYM and pod weight, seed No. / pod, weight of seeds (g) / pod increased significantly. Also, FYM gave the highest values of shelling out, protein content and ascorbic acid while gave the lowest value of carbohydrates. Also, FYM gave the highest value of total yield of spinach by increments of 108.11 and 99.42% for two growing seasons, respectively. Microbein gave the highest ascorbic acid content in spinach, and a high nitrate content caused by both mineral fertilizers, while FYM gave the lowest nitrate level. Chemical constituents of potato differed significantly from raw material. Fat content become 26.24% in potato slices fertilized by ammonium nitrate, against 12.34% only for slices fertilized by Nitrobein. Nitrate level decreased from 14.4 to 3.83% in French fries and from 12.9 to 1.7% in chips and from 11.10 to 1.86% in cooked potato by soaking it in 0.5% sodium metabisulfite solution. Nitrate in green pea seeds decreased by cooking, freezing and canning processes. The highest value of loss in nitrate level reached up to 98.04% was recorded in canned pea unfertilized and blanched in boiling water for 3 min. before canning. Nitrate level in spinach affected significantly by the interaction between fertilization, preservation method, blanching media and cooking process. Results showed that, FYM treatment gave the highest decrease in nitrate level, while two mineral fertilizers gave the lowest ones in nitrate level in spinach. |