Requerimiento de nitrógeno para alcanzar máximo rendimiento y calidad en variedades industriales de papa

the objective of this research was to determine the nitrogen (n) requirement to achieve maximum yields without affecting potato tuber quality in two processing potato varieties, innovator (inn) and gem russet (gr). the experiment was conducted during two seasons under four n rates in a randomized complete block design with three replications. after harvest, tuber yield, tuber dry matter (dm), amount of accumulated n and nitrate concentration were assessed. overall, n fertilization increased tuber yield, n accumulation and nitrate concentration, whereas tuber dm decreased. the inn variety had a more positive response to n rate than gr, and required a higher n rate to achieve maximum yields. the n requirement to maximize yield was 280 and 245 kg ha-1 for inn and gr, respectively. tuber n accumulation and tuber dm had more variation in gr than in inn because of the effect of water availability. in turn, inn tubers accumulated a higher nitrate concentration than gr ones, which indicates that each variety has a different capacity to reduce tuber nitrate content. in summary, fertilization strategies for these varieties should consider their differential behaviour regarding yield and quality, because higher n doses than required to achieve maximum yields reduce tuber dm and increase tuber nitrate concentration. under these conditions, tuber quality would be more affected in inn than it would in gr.