Temperature and precipitation effects on durum wheat grown in southern Saskatchewan for fifty years

Approximately 60% of Canadian durum wheat (Triticum turgidum L.) is produced 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 conjunction with daily precipitation and maximum daily temperature (MaxDT) data with the objective of improving our understanding of the effects of these weather variables on durum wheat grown in this semi-arid region. 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 maximum effect of these weather factors in limiting yield in the Brown soil zone was through an impact on KNum around anthesis. Hectolitre weight 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 threshold MaxDT of 20, 24, 28 and 32 degrees C indicated that temperatures >24 degrees C may be detrimental during early June although high temperatures are less common in June than in July. Yield was also negatively 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 the development of cultivars which are more tolerant of drought and high-temperature stress at anthesis.