EFFECT OF TEMPERATURE, NITROGEN FERTILIZATION AND MOISTURE STRESS ON GROWTH. ASSIMILATE DISTRIBUTION AND MOISTURE USE BY MANITOU SPRING WHEAT

The effects of early moisture stress [tillering (Tg) to last leaf visible (LLV)], late moisture stress [LLV to anthesis (AN)], and three rates of N fertilizer (44, 88 and 132 kg N/ha) on the development and moisture use characteristics of spring wheat (Triticum aestivum L. ’Manitou’) were determined under simulated irrigation in the growth chamber at day/night temperatures of 27 °C/12 °C (T27/12) and 22 °C/12 °C (T22/12). Plant height was unaffected by N and by early stress, but was reduced by late stress. Number of tillers increased until LLV, then decreased sharply and remained constant to maturity. More tillers were initiated at T27/12 than at T22/12, but by maturity there was little difference. Leaf blade photosynthetic area reached its maximum at LLV, while the non-leaf blade photosynthetic area reached its maximum at AN and constituted 75% of the total photosynthetic area at the milk dough stage. Heads comprised no more than 9% of the photosynthetic area at any time. Total plant matter accumulated s...