WHEAT PHENOLOGY IN RELATION TO LATITUDE, LONGITUDE AND ELEVATION ON THE CANADIAN GREAT PLAINS

Normal dates of phenological stages of wheat were estimated for some 1200 points on the Canadian Great Plains, using a biometeorologial time scale equation. The estimation procedure employed actual photoperiods, regression estimates of temperature normals, and coefficients determined for Marquis wheat. Differences in the phenological estimates over short distances were mainly related to elevation differences. Over the region as a whole, the date of a particular stage became progressively later with increasing distance northward or eastward. This was only partially offset by the general decrease in elevation in these directions, and by the northward increase in photoperiod. Wheat would be expected to ripen at all locations considered in Saskatchewan and Manitoba, and at those below 1400 m in southernmost Alberta and most of those below 350 m near Great Slave Lake. The estimates seemed biased toward earlinsss for ripening and lateness for planting, with very little bias for heading.