TEMPERATURE AND PRECIPITATION EFFECTS ON DURUM-WHEAT GROWN IN SOUTHERN SASKATCHEWAN FOR 50 YEARS

Approximately 60% of Canadian durum wheat (Triticum turgidum L.) is pr oduced in the semi-arid, Brown soil zone of southern Saskatchewan. The Durum Wheat Cooperative Test (DWCT) provides the means of evaluating potential new cultivars, and has been grown at Swift Current, located near the centre of the Brown soil zone in Saskatchewan, for more than 50 yr. Historical yield-related data from the DWCT were analyzed in co njunction with daily precipitation and maximum daily temperature (MaxD T) data with the objective of improving our understanding of the effec ts of these weather variables on durum wheat grown in this semi-arid r egion. The highest correlation between the weather variables and grain yield was during the period near the end of June through early July, approximately the time of anthesis. The correlation with kernel number m(-2) (KNum) was maximum near the end of June, while the correlation with kernel weight was highest around the third week of July. The maxi mum effect of these weather factors in limiting yield in the Brown soi l zone was through an impact on KNum around anthesis. Hectolitre weigh t and time-to-maturity appeared to be influenced mainly by the weather in July, while crop height was determined by the weather near the end of June. An analysis which examined cumulative heat-units above thres hold MaxDT of 20, 24, 28 and 32 degrees C indicated that temperatures >24 degrees C may be detrimental during early June although high tempe ratures are less common in June than in July. Yield was also negativel y impacted by temperatures >20 degrees C during the first 3 wk of July . Future yield gains in this semi-arid region may be dependent upon th e development of cultivars which are more tolerant of drought and high -temperature stress at anthesis.