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Fig. 1. Scatter plots with linear regression lines (orthogonal fit) and paired t-test plots of NO–3–N (µg g–1) extracted from oven-dried winter wheat samples (Feekes growth stage 7 and 10.1) and measured by flow injection analysis (FIA), laboratory microplate nitrate reductase kit (M-NaR), ion specific electrode card (ISE-card), test strip reflectometry (TSR), and field nitrate reductase kit with spectrophotometer detection (F-NaR abs). In the panels on the right, mean differences are shown as the horizontal solid lines, with the 95% confidence interval above and below depicted as dashed lines.
