Europ. J. Agronomy 30 (2009) 140–150 Contents lists available at ScienceDirect European Journal of Agronomy journal homepage: www.elsevier.com/locate/eja Multivariate analysis of water-related agroclimatic factors limiting spring wheat yields on the Canadian prairies Budong Qian ∗ , Reinder De Jong 1 , Samuel Gameda 2 Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Ave., Ottawa, ON, K1A 0C6 Canada article info Article history: Received 15 April 2008 Received in revised form 19 August 2008 Accepted 9 September 2008 Keywords: Spring wheat yield Agroclimatology Versatile Soil Moisture Budget Principal component analysis Canonical correlation analysis abstract Water use by spring wheat and soil water contents at meteorological stations on the Canadian prairies were simulated with the Versatile Soil Moisture Budget model for different crop growth stages. Six water-related agroclimatic indices at five growth stages (seeding–emergence, emergence–jointing, jointing–heading, heading–soft dough and soft dough–harvest) and previous non-growing season were correlated to spring wheat yields in the three prairies provinces and in the entire prairie region for the years 1976–2006. Principal component analysis was applied to explore major modes of joint variability in the regional water-related agroclimatic indices. Canonical correlation analysis was employed to further identify joint variability patterns of the water-related indices associated with regional spring wheat yields. Results showed some common features of the effects of the water-related factors at different growth stages: lower-than-normal moisture stress at the jointing–heading stage favoured spring wheat yields in all three provinces. Regional differences were also seen, for example, a slight moisture stress at the heading–soft dough stage could be beneficial to spring wheat yields in Manitoba because of its relatively wetter climate compared to the other two provinces. The results can be used for a better understanding of the effects of water-related agroclimatic conditions at different growth stages on final spring wheat yields on the Canadian prairies, leading to the improvement of crop management. The results can also be used in regional yield forecasting and in the projection of climate change impacts on crop production. This study provided an example of how to quantify crop–climate relationships by the use of statistical multivariate analysis tools. Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved. 1. Introduction The Canadian prairies account for about 85% of the arable land in Canada, making it the most important agricultural region of the country (Campbell et al., 2002). This region is dominated by cereal grain production, especially hard red spring wheat (Triticum aes- tivum L.), although economic advantages of crop diversification have resulted in a steady increase in the production of oilseeds. While spring wheat yields have increased over the past 30 years, the interannual variability is large, mainly as a result of climatic variability (Qian et al., in press). Understanding the factors that limit crop yields is essential to regional yield forecasting and improving crop management techniques. Moreover, such factors must be known for the devel- ∗ Corresponding author. Tel.: +1 613 759 1641; fax: +1 613 759 1924. E-mail addresses: qianb@agr.gc.ca (B. Qian), DeJongr@agr.gc.ca (R. De Jong), gamedas@agr.gc.ca (S. Gameda). 1 Tel: +1 613 759 1520; fax: +1 613 759 1924. 2 Tel: +1 613 759 1532; fax: +1 613 759 1924. opment of adaptation strategies to climate change, for example, effective irrigations at key crop growth stages under a warmer and dryer climate scenario. Moisture stress is recognized as the dominant limiting factor to spring wheat yields on the Cana- dian prairies (Walker, 1989; Raddatz et al., 1994; Campbell et al., 1997). Campbell (1968) studied the influence of soil moisture stress applied at various stages of growth on the yield compo- nents of Chinook wheat at Swift Current, Saskatchewan. He found that the growth stage from shot-blade (the approximate growth stage equivalent to jointing of the biometeorological time scale in this paper) to anthesis/soft dough was most sensitive to soil moisture stress. Bauer (1972) reported that the heading to soft dough stage is the most sensitive one to water stress. Bootsma et al. (1992) indicated that lack of moisture during the period from jointing to soft dough is most likely to result in a yield reduction on the Canadian prairies. Desjardins and Ouellet (1980), deter- mining the importance of various phases of wheat growth on its final yield at selected locations in Canada, found that the most important phases were essentially the same for regions with sim- ilar climates, but were different for regions with widely different climates. 1161-0301/$ – see front matter. Crown Copyright © 2008 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.eja.2008.09.003