Published online by Cambridge University Press: 27 March 2009
The effects of the physical environment in Manitoba on the growth of Vicia faba minor cv. Diana were monitored during 1974–5. Seed yields and dry-matter production were considerably lower than have recently been achieved with similar varieties in Britain. Factors integral to the prairie environment are suggested to be the cause of this productivity differential. In particular, high soil moisture stress appears to be capable of severely reducing yields especially when experienced during the early phases of reproductive development. Satisfactory dry-mayEer production is not likely to be achieved if the seasonal soil heat accumulation (above 5 °C) is less than 1000 degree days. Low soil temperatures in the initial vegetative growth stage may also be responsible for the failure to achieve potential crop growth. Similarly high ambient temperatures (above 20°C) appear to be deleterious to crop growth.
Field-bean heat units were defined to facilitate the examination of potentially useful atmospheric heat on crop growth.