1 November 2003 Secondary seed dormancy prolongs persistence of volunteer canola in western Canada
Robert H. Gulden, Steven J. Shirtliffe, A. Gordon Thomas
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In western Canada, little is known about the seedbank ecology of volunteer canola. Therefore, integrated recommendations for the management of this weed are limited. In this study, we investigated the seedbank persistence and seedling recruitment of two spring canola genotype groups with different secondary seed dormancy potentials under contrasting tillage systems. The study was conducted at two locations with different soils in the Mixed Moist Grassland ecoregion of Saskatchewan. A single cohort seedbank was established in 1999 and was followed for 3 yr in successive wheat crops. In a separate laboratory study, the six canola genotypes examined were classified as those with high and those with medium potentials for the development of secondary seed dormancy (HD and MD, respectively). After one, two, and three winters, maximum persistence of 44, 1.4, and 0.2% of the original seedbank was observed among the treatments, respectively. In 2001, HD canola genotypes tended to exhibit 6- to 12-fold greater persistence than MD canola genotypes, indicating lower seedbank mortality in HD canola. Seedling recruitment of HD canola also was higher than MD canola when differences were observed between these genotype groups. Therefore, long-term seedbank persistence of canola can be reduced by growing genotypes with low inherent potential for the development of secondary seed dormancy. The proportion of persisting seeds tended to be higher under conventional tillage than under zero tillage because of lower seedbank mortality, but no clear distinction in seedbank persistence in terms of absolute time could be made between these two tillage systems. Volunteer canola seedling recruitment followed the pattern of a typical summer-annual weed, where seedling emergence was observed only during May and June.

Nomenclature: Canola, Brassica napus L.; wheat, Triticum aestivum L.

Robert H. Gulden, Steven J. Shirtliffe, and A. Gordon Thomas "Secondary seed dormancy prolongs persistence of volunteer canola in western Canada," Weed Science 51(6), 904-913, (1 November 2003). https://doi.org/10.1614/P2002-170
Received: 10 December 2002; Accepted: 1 April 2003; Published: 1 November 2003
conventional tillage
secondary dormancy
seedbank longevity
seedling recruitment
zero tillage
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