Comparing the adaptation of sunola, canola and mustard to three soil climatic zones of the Canadian prairies

Sunola (Helianthus annuus L.) emerged in the early 1990s as a new drought- and heat-tolerant oilseed crop option for prairie producers. This study was conducted to compare the agronomic performance of sunola with that of canola (Brassica napus L. and B. rapa L.) and mustard (B. juncea L.). In 1993 and 1994 a spring seeding date experiment comparing crop maturity and grain yield of sunola, canola and mustard was conducted at three locations: Swift Current and Scott in the semi-arid Brown and Dark Brown soil zones, respectively, and Melfort in the subhumid Black soil zone. Additionally, a tillage system experiment was conducted at Swift Current that compared grain yield and water-use-efficiency (WUE) of sunola and mustard grown in four tillage treatments: tilled, and untilled fallow, and tilled, and untilled wheat stubble. In the more typical 1994 season, the average thermal time to reach maturity for sunola was 1200 growing degree days (GDD), consistent for all locations, and was greater than that required for B. napus by 70 to 320 GDD (1-4 wk), depending on location. When compared with the seed yield of the Brassica spp. oilseeds, sunola averaged 59% at Swift Current, 54% at Scott, and 94% at Melfort. The WUE for sunola was 3.0 and 2.9 kg ha(-1) mm(-1) when grown on fallow and wheat stubble, respectively, compared with 5.6 and 4.8 kg ha(-1) mm(-1) for mustard. Due to its low seed yield potential and low WUE, sunola is not well adapted for production in the semi-arid Brown and Dark Brown soil zones.