EFFECT OF NITROGEN, TEMPERATURE, GROWTH STAGE AND DURATION OF MOISTURE STRESS ON YIELD COMPONENTS AND PROTEIN CONTENT OF MANITOU SPRING WHEAT

Manitou spring wheat (Triticum aestivum L.) was grown at combinations of three day/night temperatures (27/12 °C, 22/12 °C and 17/12 °C), three levels of fertilizer nitrogen (58, 116 and 174 kg N/ha), and three moisture stresses, nominally −0.3, −15 and −40 bars. All plants were initially grown at −0.3 bars; one moisture treatment was carried through to maturity at this water potential while the remainder were stressed at −15 or −40 bars from either (i) four-tiller, (ii) boot, or (iii) late flowering stage, to maturity. Under the conditions of this experiment, temperature was the most important factor affecting yield and protein, and moisture stress the least important. Yields were equal at 17 and 22 °C, but greater than at 27 °C. Protein was equal at 17 and 22 °C and less than at 27 °C. Yield increased with nitrogen fertility except at the highest temperature or when high moisture stress was applied from the boot stage. Plants grown under high moisture stress through the boot stage (i.e., stressed from ti...