Concentration changes of Lysine and Methionine amino acids in potatoes varieties affected by different levels of Nitrogen fertilizer

In order to evaluate the effect of different levels of nitrogen fertilizer on Lysine and Methionine amino acids of different potato varieties, an experiment was conducted during 2011 growing season at the research farm of Agriculture Faculty of Mohaghegh Ardabili University on a factorial design base on randomized complete block in 3 replications. The first factor consists of 3 levels of nitrogen fertilizer (0, 100 and 200 kg net nitrogen per hectare) and the second factor includes potato varieties (Agria, Marfona, clone B5 and clone B6). Results showed that the main effects of variety were significant on Lysine ratio in dry matter, protein percent in tuber at 1% of probability. Also it had significant effect at 5% of probability on Methionine ratio in dry weight and the Lysine of tuber protein but Methionine of tuber protein was not affected. Main effect of nitrogen fertilizer on Methionine of tuber protein, Lysine in dry weight and tuber protein, percent of tuber protein, was significant at 1% of probability although the main effect of Methionine in dry weight was significant at 5% of probability. Interaction effect of cultivar×fertilizer had just shown significant effect on the percent of protein of tuber. Methionine in dry weight of Agria cultivar and fertilizer level of 100 kg had highest mean. The amount of Lysine in dry weight of cline B5 and protein in Marfona cultivar were the highest means. Applying 100 kg nitrogen fertilizer caused significant increase in Lysine amount in biomass in contrast to other fertilizer levels. Lysine in protein of tubers decreased mainly with increasing fertilizer, so applying no nitrogen fertilizer had the highest and 200kg had the lowest Lysine in protein of tubers.