Reaction of newly registered potato varieties to different nitrogen supplies

In 2008 and 2009, in field trials at the Changins-Nyon (Vaud canton) and Zurich-Reckenholz sites, respectively, the two research stations of Agroscope Changins-Wädenswil ACW and Agroscope Reckenholz-Tänikon ART investigated the varietyspecific nitrogen (N) requirement of the potato varieties Gourmandine, Jelly, Laura and Lady Jo (the latter at Changins only). The N levels varied from 0 to 200 kg N per hectare. All varieties reacted to the increasing N supply with a higher gross- and marketable yield. From an N-application level of 120 kg/ha onwards, however, no significant surplus yields were demonstrated. The Gourmandine variety produced significantly higher gross- and marketable yields than Jelly and Laura. The higher the N supply, the lower the starch content of the tubers. Tubers from plants fertilised with N tended to exhibit a slightly higher brushing susceptibility than those from the non-fertilised treatment. Crisps made from the tubers of non-fertilised plants were slightly lighter in crisp colour than those of the tubers of the fertilised plants. The Gourmandine, Jelly and Laura varieties produce high marketable yields at average N-application levels of 100 to 120 kg N/ha. These trials confirm the significant influence of the weather over the year as well as the site conditions on potato yields.