Nitrogen (N) management is critical in optimizing potato (Solanum tuberosum L.) yield and reducing environmental pollution. Several plant and soil based tests were proposed for assessment of N status in crop plants. Aim of this study was to evaluate the convenience of plant based tests (leaf chlorophyll content index (CCI) and petiole nitrate-nitrogen (NO3-N) concentrations) and soil based test (soil nitrogen (Nmin) content) for estimating potato N status. Experiment was conducted in North West region of Croatia in 2011 growing season as randomized complete block design with four replications. Treatments were four N rates, 50, 100, 150 and 200 kg N ha-1. At pre-plant 50 kg N ha-1 was applied as NPK 7:20:30. Four side-dressed N rates, 0, 50, 100 and 150 kg N ha-1 were applied 45 days after planting (DAP). CCI and petiole NO3-N concentrations were measured at 58 and 98 (DAP), while soil Nmin content was measured before planting, 58 DAP, 98 DAP and after harvest. No significant differences in total tuber yield were determined between 100, 150 and 200 kg N ha-1 treatments. Significantly highest residual Nmin content (33.25 kg ha-1) after harvest was determined on plots fertilized with 200 kg N ha-1, indicating potential N leaching during fall and winter. Significant linear relationship between petiole N-NO3 and N treatments were determined at 58 DAP (R2=0.32) and 98 DAP (R2=0.75) and between CCI and N treatments at 98 DAP (R2=0.62). Significant linear relationship between soil Nmin content and N treatments were determined at 58 (R2=0.57) and 98 DAP (R2=0.56). Plant based tests are better correlated with N treatments at later growth stages in which applied N could be utilized by the crop.

nitrogen management; potato; chlorophyll content index; petiole nitrate-nitrogen concentration; soil nitrogen content

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia