DETERMINATION OF THE NITROGEN STATUS OF IRRIGATED POTATO CROPS .1. CRITICAL NUTRIENT RANGES FOR NITRATE-NITROGEN IN PETIOLES

This paper describes the derivation of critical nutrient ranges (CNR) for nitrate-N in petioles of potato plants (Solanum tuberosum L.) at different sampling times during crop growth for use as interpretation standards or ’target’ levels when assessing plant nitrogen (N) status. Nine rates of N from 0 to 320 kg/ha were applied in randomised block experiments to the cultivars Atlantic, Coliban or Kennebec at 5 sites over 2 years. Petioles of the youngest fully expanded leaves were analysed for nitrate-N at 5 sampling times. Petiole samples were collected when the length of the longest tuber was >2, 10, 25, 35 and 50 mm. © 1990, Taylor & Francis Group, LLC. All rights reserved.