Effect of seeding date on canola seed quality and seed vigour

Abstract

Seedling vigour is a key critical component to produce well-established canola (Brassica napus) seedlings under less than ideal conditions in western Canada. Our objective was to determine if seed lots from late October (fall) or early spring (April) seeding dates improve seed vigour relative to mid-May (May) seeding dates. We compared seed size, seed maturity, germination percentage, and seedling emergence under controlled-environment conditions from six seed lots obtained from fall-sown (1997, 1998), April-sown (1998, 1999) and May-sown canola (1998, 1999) cv. Quest. On average, 80% of fall-derived seed for both years was larger than 1.7 mm compared to only 32% for May-derived canola seed. April-derived seed was intermediate. Fall and April derived seed were considered 40% mature compared to 16% for May-derived seed. In germination tests at 8°C, May derived seed germinated and emerged slower with a lower total germination percentage compared to fall-and April-derived seed lots. Priming reduced differences in emergence between the seed lots. Field studies at Scott, SK, sown in the fall of 1999 and 2000, and in early May of 2000 demonstrated that seed derived from fall- and April-sown canola produced higher plant densities, higher biomass at bolting, and higher seed yield than seed derived from May-sown canola. Yield was 10 to 45% less from seed derived from May-sown canola than seed derived from fall- and April-sown canola. This study established the impact of seeding date on seed quality and vigour, which in turn affected emergence, seedling vigour and yield. Also, seed vigour slowly declined within 1 yr, primarily with seed derived from the May-sown canola.