Effect of Nitrogen and Potassium Fertilization on Productivity and Quality of Four Potato (Solanum tuberosum L.) Cultivars

This study was carried out at the El-Kawther Experimental Farm, Faculty of Agriculture, Sohag University, Sohag, Egypt during two successive seasons of 2014/2015 and 2015/2016 to investigate the effect of nitrogen and potassium fertilization on the productivity and quality of four cultivars of potato (Sponta, Brn, Oceana and chara) grown under Sohag Province conditions. Three nitrogen/potassium rates (90N: 48K, 120N:90K and 150N:120K units feddan. The obtained results clearly showed that there were significant differences among the four cultivars and the three levels of fertilization among the most of studied characters under this study. The cultivar Chara is the best one on the total yield (9.88 and 10.03 ton/ fed), yield component and most of quality traits. In the case of sowing in the sandy soils under Sohag conditions it was been that the third level (N150:K120) gave the best results. Sponta cultivar was the best on some of the quality traits such as dry matter and starch. Finely the cultivar Chara with the third level of fertilization is the best in the total yield and its components and most of quality traits. INTRODUCTION Potatoes (Solanum tuberosum L.) is considered one of the most important strategic crops for the populations all over the world and comes at the fourth stage after wheat, rice, and maize. It plays a vital role in the Egyptian diet it has production nearly 4265178 tons from about 381379 fed with average yield 11.184 ton per fed (Agriculture Directorates in Governorate, 2014). Potato is considered as the most important tuber crop. Moreover it is an important vegetable and a good source of antioxidants. Potato is a major source of inexpensive energy; it contains high levels of carbohydrates and amount of vitamins B, C and minerals (Muthoni and Nyamongo 2009).The tubers are a good source of starch, proteins, vitamins, sugars, minerals and other useful substances when eaten as an essential dish and with major quantities for long time (Blagoeva et al., 2004). Potato composition various greatly between different cultivars but generally comprises 63-87 % water, 13-37 % dry matter, 13-30 % carbohydrate, 0.7 -4.6 % protein 0.02-0.96%lipids , 0.2Keywords