Varieties and Pre Harvesting Treatment for Growing Polish Canola (Brassica rapa L.) in Interior Alaska

Barley has been a mono cereal crop grown in the Delta Junction area of Alaska since 1970s. A rotational crop is needed for weed control and conservation tillage for sustainable crop production. Due to short growing season constrains, canola when used as a rotational crop currently resulted low marketability because of high green seed content (>2%). The objective of this research is to determine if glyphosate when used as a desiccating chemical could promote early maturity and reduce green seed content of canola. Four Polish canola cultivars were treated with direct combine (as a control), pushing (to stop growth) and desiccating in two locations in Alaska USA in a randomized complete block design with four replicates from 2007 to 2009. Glyphosate was sprayed, and pushing was conducted around August 15 each year. Results showed that 'Hysin 110' treated by glyphosate consistently had ≤ 2% green seed content in three years in contrast with 'Reward' despite a wide variation of weather conditions. The growing degree days were dramatically different among the three years, with 2009 close to the 29-year norm, 2008 was lower and 2007 was higher than the norm. No residual glyphosate was found in the seeds from the desiccating treatment. In conclusion, desiccating treatment together with a good short growing season Polish canola cultivar can make canola grown as a rotational crop in Alaska’s short growing season conditions.