Effect of Organic, Nitrogen and Potassium Fertilization Treatments on Growth, Yield and Chemical Contents of Two Cultivars of Potato (Solanum tuberosum)

Two field experiments were carried out at the Research farm, faculty of Agriculture, Alexandria University, during summer seasons of 2008 and 2009. The objective of the present study was to evaluate  the response of two potato cultivars (valour and Lady Belfour) to different levels of  poultry manure  (10 and 20 m3/ fedan) and a combination of nitrogen and potassium mineral fertilizer {(0-0), (80-24), (120-48), (160- 72) and (200- 96) kg N-k2O / fedan}. The results showed that Lady Belfour had higher vegetative growth characters and higher chemical composition (protein content, tuber dry matter and K content) in comparing to Valour. However, Valour exceeds Lady Belfour in yield component characters and in the percentage of large tubers. Concerning, the effect of poultry manure data indicating that 20m3 / fed. showed superior effect on all vegetative growth characters ,as well as, total tuber yield and its component. However, the response of higher rate of poultry manure didn’t show a significant reflect on different tuber sizes and decrease the percentage of dry matter and starch content. It could be concluded that the best combination of mineral fertilizer which represent the highest total yield / fed and the highest percentage of large tubers is 160-72 kg  N-K2O / fed. in both growing seasons. However, the highest rate 200-96 kg N-K2O / fed. promoted the highest mean value of N,P,K  and protein content. Valour cultivar showed superior performance in total yield / fed. when combined with either 20m3/ fed or 160kg N-K2O / fed. The best organic mineral treatment combination on total yield was 20m3 combined with 160 kg N-K2o. The results also, show a significant positive relationship between mineral fertilization and total yield of potato with a correlation coefficient reach to 95% and 96% in both growing seasons.