Do Canola Hybrids and Open-Pollinated Varieties Require Different Seeding Rates?.

Some producers have turned to planting canola in 30-in. rows as a strategy to take advantage of residue management options that facilitate planting canola in high-residue cropping systems. The objective of this study was to determine the effect of seeding rate on performance of hybrid and open-pollinated winter canola cultivars in 30-in. and 9-in. rows. Experiments were conducted in 2013 to 2017 at two K-State Research and Extension facilities. Treatments were four locally adapted cultivars (two hybrids and two open-pollinated cultivars) and three or five seeding rates for a total of twelve or twenty treatments in each experiment. Due to nearly complete winter stand loss of hybrids in the experiment planted in 2013, only open-pollinated cultivars were harvested. No experiments were harvested for yield in 2015 because of nearly complete stand loss due to winter kill. Winter survival tended to increase as the number of plants present in the fall decreased. Bloom occasionally was delayed, and harvested seed moisture tended to be greater when fewer plants were present in the spring, likely due to a greater percentage of buds forming on branches. In 30-in. rows, seeding rate had no impact on yields in 2016 when yields were less than 2,000 lb acre^-1, but yields were reduced at extremely low or high seeding rates in 2017 when yields were greater than 2,000 lb acre^-1. In 9-in. rows, seeding rate did not affect yields in 2014, but in 2016 and 2017, both hybrids and open-pollinated cultivars maximized yield at 225,000 to 375,000 seeds acre^-1 with reduced yields at 150,000 seeds acre^-1. Although hybrids maintained greater yields than open-pollinated cultivars at sub-optimal seeding rates in 9-in. rows in 2016, yield responses to seeding rate were similar for hybrids and open-pollinated cultivars in most experiments at both row spacings.