A retrospective look at short-season soybean cultivar development in Ontario

Cober, E. R. and Voldeng, H. D. 2012. A retrospective look at short-season soybean cultivar development in Ontario. Can. J. Plant Sci. 92: 1239–1243. Canadian soybean production has increased from about 63 000 ha in 1951 to 1.2 million ha in 2006 with expansion from southern Ontario to shorter season areas. From 1971 to 2000, soybean production in Ontario increased sixfold. Using annual reports from 1971 to 2000 of short-season trials in Ontario, we found that the number of reported cultivars remained between three and five until 1984 when the number of cultivars started to increase at the rate of about 2.5 yr−1. The amount of time that cultivars remained in the reports has declined from 12 to 4 yr on average over the 30-yr period. Long-lived cultivars, however, were developed throughout the period including: Hardome, Merit, Evans, Maple Arrow, Bicentennial, Maple Glen, KG 41, OAC Eclipse, 9071, OAC Bayfield, PS 36, and S03-W4. Over the 30-yr period of cultivar testing, short-season seed yield increased about 600 kg ha−1, while mean time to maturity decreased about 10 d. During the same time, mean Ontario commercial seed yields increased about 750 kg ha−1. Over the 30-yr period, the number of short-season cultivars in annual reports increased 36-fold, while provincial yield increased only 1.4-fold. If the number of cultivars in annual reports is an indication of breeding effort, large research investments may be necessary to increase future yield improvement.

Yield prediction for mixed species stands in boreal Ontario

Wood supply of the major industrial species groups (spruce–pine–fir [Picea–Pinus–Abies spp.] and poplar [Populus spp.]) in the boreal forest of Ontario is forecast to fall below demand in the relatively near future. This has lead to more interest in the growth and yield of mixedwood forests. Mixedwood stands are defined for forest management planning as stands in which 26% to 75% of the canopy is softwood. With an average growth rate one-third higher than the average for all forest types combined, mixed species stands have potential to mitigate some of the shortfalls. This paper reviews the history of yield curve development in Ontario and some of the current initiatives in mixedwood modeling. The Forestry Research Partnership, a partnership between Tembec, the Ontario Ministry of Natural Resources, the Canadian Forest Service, and the Canadian Ecology Centre, was formed in 1999. One of the first projects of the Partnership was to update the provincial yield curves. These updated curves provide good estimates of yield for mixedwoods on upland, drier sites but mixedwoods on moister sites need to be further stratified by leading species. Mid-rotation activities such as density regulation and partial harvesting in the selection or shelterwood silvicultural systems are generally tree-level activities. These are more compatible with tree-level models. Ontario is calibrating the Forest Vegetation Simulator (FVS) for use in Ontario and this shows particular promise in mixedwood modeling. Key words: mixedwood growth, yield tables, FVS