Effects of nitrogen fertilization and in-row seedpiece spacing on yield of three potato cultivars in Prince Edward Island

AC Novachip and NorWis were recently introduced as new potato (Solanum tuberosum L.) chip cultivars on Prince Edward Island (P.E.I.), Canada. Variability of nitrogen application and in-row seedpiece spacing, required for maximum yield, exist among cultivars presently grown in P.E.I. This study was conducted to determine the N rate and in-row seedpiece spacing required for optimum production of AC Novachip and NorWis compared to the standard cultivar Norchip, and also, to determine the effects of treatments and harvest dates on AC Novachip. Treatments included N applied at 90, 134, and 179 kg/ha with in-row seedpiece spacings at 20.3, 25.4 and 30.5 cm. In addition to the 120 day harvest for all three cultivars, treatments for AC Novachip were also harvested at 80 and 100 days after planting. For the 120 day harvest, yield of Canada No. 1 size tubers was higher for NorWis compared to Norchip while yields for AC Novachip and Norchip were similar. Nitrogen application had no effect on yields of AC Novachip. Similar to Norchip, increasing the rate of applied N more than 134 kg/ha resulted in little or no increase in yields of NorWis. Yields of Canada No. 1 size tubers decreased as in-row spacing increased for AC Novachip and were greater at 25.4 compared to 30.5 cm spacing for Norchip. In-row seed-piece spacing had no affect on Canada No. 1 size tuber yields of NorWis. Increasing the days to harvest increased the yields of AC Novachip. Nitrogen rate or in-row spacing had no effect on Canada No. 1 yields of AC Novachip at the 80 and 100 day harvests. The results of this study suggest that little gain in yield of Canada No. 1 size tubers for NorWis, similar to the standard cultivar Norchip, can be obtained with N application more than 134 kg/ha or for AC Novachip by increasing the rate of N from 90 to 179 kg/ha. Unlike NorWis yields of AC Novachip and NorWis are reduced when in-row seedpiece spacing is increased from 25.4 to 30.5 cm.