Effects of Nitrogen, Temperature, and Moisture Regime on the Yield and Protein Content of Neepawa Wheat

Experiments were conducted in growth chambers growing wheat on a soil initially low in NO 3 -N. At rates up to 100 ppm N, grain yield increased with succeeding increments of fertilizer-N. Increased temperatures (15, 21, and 25 C) significantly decreased grain yield in most instances. Low to moderate stress soil moisture regimes (0.3–0.5 and 0.3–2.8 bars) had no significant influence on grain yield. A line was plotted for percent protein vs. added fertilizer-N resulting in a concave protein curve, with an initial decrease in protein to 50 ppm N and a subsequent rise with 100 and 200 ppm N. At each level of N, a close negative correlation was shown between percent protein and grain yield. The effect of increased temperature in increasing percent protein was found to be mostly an indirect effect through the influence of temperature on grain yield. Moisture regime was found to have no significant direct effect on percent protein.