DEPTHS, RATES AND DATES OF SEEDING AND YIELD OF YELLOW MUSTARD (SINAPIS-ALBA L) IN WEST-CENTRAL SASKATCHEWAN

From 1984 to 1989, studies were conducted to evaluate the effects of depths, rates and dates of seeding on yellow mustard (Sinapis alba L.). As seeding depth was increased, emergence and development to maturity were delayed and plant densities were decreased. Seeding at 12- or 25-mm depths resulted in 4-year average yields of 1447 and 1424 kg ha-1 respectively, whereas seeding at 50 or 75 mm gave yields of 1177 and 987 kg ha-1, respectively. Where the soil was too dry to support germination at 25 mm, seeding at depths up to 50 mm gave similar yields to seeding at lesser depths. Seeding at 4 kg ha-1 reduced yields compared with seeding at 8, 12 or 16 kg ha-1 when averaged over 6 yr. As seeding rates increased, a lower proportion of seedlings emerged and developed into mature plants, apparently due to increased competition between plants. Increasing rates of seeding reduced the number of branches and pods produced per plant and decreased the number of days to mature. Seeding between 1 May and 26 May had only a small impact on yields in most years; however, further delays in seeding decreased yields substantially. As seeding was delayed, the number of days from seeding to emergence and to maturity decreased, and deviations from this trend were usually associated with periods of cool wet weather.