Determination of effective nitrogen level to optimize yield and quality of potato varieties of Connect and Masai

Although the Department of Agriculture in Sri Lanka provides fertilizer recommendations for local potato cultivation, farmers do not comply with them. Fertilizer is overused mostly in up-country areas causing economic losses as well as health and environmental issues. There are high nitrogen (N) efficient potato varieties such as CONNECT and MASAI that produce optimum yield under lower N but show abnormalities such as secondary growth, tuber cracks, deformed or misshapen tubers and increased tuber rotting under higher N. A field experiment was conducted in Nuwara-Eliya, Sri Lanka to identify the effective N level to optimize yield and quality of potato varieties of CONNECT and MASAI. The experiment was arranged as a Randomized-Complete Block Design with five N levels (110, 150, 190, 230, and 270 kg ha-1) and replicated thrice. Phosphorus (P, 100 kg ha-1) and potassium (K, 250 kg ha-1) levels were kept constant across treatments. N level had no significant (P>0.05) effect on tuber yield or dry matter content in both varieties confirming that the yield was not affected even by the lowest N level used in the study. In conclusion, the lowest N level of 110 kg ha⁻1 can be recommended for potato varieties of MASAI and CONNECT as it is an economically and environmentally sound option as it did not cause any yield or quality reduction in potato in the present study.