Seeding Date and Hybrid Herbicide Resistance Influence On Canola Performance.

Newer canola hybrid types and wide variability of soils and weather across North Dakota with approximately 90% of U.S. production, has prompted re-evaluation of seeding date influence on canola (Brassica napus L.) performance. Seeding date is one of the first decisions producers make to achieve high crop performance and knowing when yields typically decline with late seeding near their farms is important to producers to avoid yield loss. The objective of this study was to determine the influence of seeding date and hybrid herbicide resistance on canola performance at several diverse locations across North Dakota. A RCBD, with four replicates, in a split-plot arrangement with seeding date the main plot and hybrid the subplot was conducted at the Carrington, Hettinger, Langdon, and Minot Research Extension Centers in 2010 and 2011. Five seeding dates were spaced at 10 d intervals and began in late April or early May and extended to about June 10. Herbicide resistant hybrids included a Roundup Ready and Liberty Link hybrid solid-seeded at 1,605,500 pure live seed/ha in plots approximately 1.5 x 6.2 m with a row-spacing of 15 cm. Yield was maintained at the first two seeding dates before decline at later dates at the northern Carrington and Minot locations, but at the southern Hettinger location yield decline occurred with each successive seeding date. Seed yield reduction ranged from 50 to 60% from Date 1 to Date 5 at the Carrington, Hettinger, and Minot locations. At the northeastern Langdon location yield was maintained at the early June seeding date at levels equal or greater than from earlier seeding dates in both years. Seed oil content decreased from 4 to 8.5% from Date 1 to Date 5 among locations, but oil content was generally similar at Dates 1 and 2 followed by decline at later seeding dates. The seeding date by hybrid interaction indicated hybrids responded differently at early and late seeding dates at two locations. The results indicate early May to early June seeding dates produced equal yield performance at the Langdon location. Seeding before 15 May would produce greatest yields at Carrington and Minot, and seeding in late April or early May would produce greatest yields at the southwestern Hettinger location.