Nitrate in potatoes. 1. The effect of fertilization and storage on the nitrate content in 5 genotypes grown in widely separated localities

The effect of nitrogen fertilizer at levels of 50, 100 and 150 kg per ha, and of the length of storage on the nitrate content of potatoes was studied in field experiments. Five genotypes were grown at five sites differing widely in day length, temperature and precipitation. The nitrate concentration of the tubers increased significantly with increasing nitrogen supply, but less in some genotypes than in others and there were significant differences between localities. The highest nitrate concentration was found at the locality with the coolest growing season, the lowest at one with a relatively high summer temperature. Nitrate in tubers decreased significantly during storage periods of 90 and 180 days. The overall concentration of nitrate in the tubers was low event at the highest N dressing, and the tubers can safely be recommended for human consumption.