the effect of n and k fertilizer on qualitative changes in potato during storage

a field investigation was conducted to evaluate the effect of n and k fertilizers on qualitative and quantitative changes of potato tubers during five months of storage. this study was carried out in three replications at five levels (0, 60, 120, 180 and 240 kg/ha) of nitrogen and three levels (0, 75 and 150 kg/ha) of potassium fertilizer during 2004-2006. measurements were recorded monthly. the results showed that the effect of different treatments of n and k fertilizers and storage period, and their interaction, significantly affects the quantitative changes in tubers (p<0.05). the greater the application of n fertilizer, the greater the loss of water, vitamin c, starch and reduced sugar content of the tubers during storage and an increase in k fertilizer decreased these changes. according to the results, it is better to use 180 kg/ha n with 150 kg/ha k when planning to store potatoes for three months or less. if the storage period is more than three months, it is highly recommended to use 120 kg/ha nitrogen and 150 kg/ha potassium fertilizer.