DISPOSITION OF NITROGEN AND SOLUBLE SUGARS IN MANITOU SPRING WHEAT AS INFLUENCED BY N FERTILIZER, TEMPERATURE AND DURATION AND STAGE OF MOISTURE STRESS

Manitou spring wheat (Triticum aestivum L.) was grown at combinations of three different day/night temperatures (27/12 °C, 22/12 °C and 17/12 °C), three levels of fertilizer N (58, 116 and 174 kg N/ha), and three moisture stresses (nominally −0.03, −1.5 and −4.0 MPa) applied for four durations (viz., no stress throughout, stress from (i) four-tiller (Tg), (ii) boot (Bt), or (iii) flowering (Fl) stages to harvest (Hvst)). Plant and soil samples were analyzed at eight growth stages. Plants grown at 22/12 °C or 17/12 °C and given 116 or 174 kg N/ha lost some N between heading and flowering. Plant N content (dry weight × % N) was depressed by moisture stress in proportion to the duration of the stress even though N concentration was increased. Plant N content was not greatly affected by temperature due to the compensating effects of temperature on dry matter and N concentration. N content of heads was depressed most by moisture stress applied from the Bt stage. Between Fl and Hvst the roots, leaves and stems ...