Evaluating the potential for double cropping in Canada: effect of seeding date and relative maturity on the development and yield of maize, white bean, and soybean

Abstract

Double cropping is not presently a common practice in Canada. The long-term climate averages, however, suggest that the practice should be possible in the most southern portions of the country. The study described herein represents the first simultaneous evaluation of three crops—maize, soybean, and white bean—seeded at five seeding dates spanning late June through early August in the most southern region of Canada. Germplasm was chosen such that physiological maturity could theoretically be reached if seeded following winter wheat. Results indicate that, following summer seeding, development in all three crops was primarily driven by thermal requirements. Only the pod filling stage of soybean was influenced by the declining daylengths of autumn, and this effect was most pronounced in germplasm of longer relative maturity. Yields of white bean and maturity group 00 soybean were unaffected by seeding up to the third week of July, whereas yield of maize and higher maturity group soybeans declined from June onward. For the latter, declining yields were primarily attributable to the interaction of seeding date and relative maturity and their effect on season length. These results clearly demonstrate that with the appropriate selection of germplasm, there is a seeding date window where maize, soybean, or white bean can be expected to reach physiological maturity as a double crop in Canada.