Modified Transplant Production Techniques to Increase Yield and Improve Earliness of Brussels Sprouts

Field studies were conducted to determine the effects of row covers (no row cover or Agryl P-17), seeding date, and seeding method (seeding in a furrow or into a smooth soil surface) on the development, harvest date, and yield of brussels sprouts (Brassica oleracea L. (Gemmifera Group)) grown in southwestern British Columbia. The treatments were applied to the plants in the seedbed after which the plants were transplanted in the field and grown to horticultural maturity. In both years, row covers increased soil temperatures and advanced seedling development and transplanting dates compared with uncovered treatments. Leaf weight ratio (LWR) decreased, specific leaf area (SLA) increased, and leaf area ratio (LAR) was unaffected by the application of row covers. Early seeding also promoted early transplanting. In 1987, plots were harvested when plants reached horticultural maturity. There was a linear effect of seeding date on harvest date, early seeding promoted an early harvest, and row covers advanced the sprout harvest of plants seeded earliest (24 Mar). In 1988 all treatments were harvested from 17 to 19 Oct. and marketable yield was improved by early seeding and by row covers. Seeding method did not influence plant growth or yield. Brussels sprouts require relatively long growing seasons, which ean limit their production in southwestern British Columbia. Therefore, the crop is started early in the season in outdoor seedbeds from which transplants subsequently are taken for stand establishment in production fields. Late-season harvesting of sprouts may result in frost damage (Maurer, 1964) or an in- creased incidence of internal browning (Lewandowska, 1985). Earlier seeding, transplanting, and harvesting could improve the quality and yield of sprouts (Kronenberg, 1975). Floating row covers have been used successfully to advance the production of many crops by elevating soil and air temper- atures (Bonanno and Lament, 1987; Decoteau et al., 1986; Hemphill and Mansour, 1986; Nelson and Young, 1987; Wilson et al., 1987). Most reports are concerned with transplanted crops or crops with relatively short growing seasons. Row covers placed over direct-seeded crops may abrade developing seedlings; thus, seeding into furrows has been recommended to avoid seedling damage (Gerst, 1985). The advantages of promoting earlier plant development by using transplants or row covers may not be sustained with long-season crops. This study was initiated to determine if earliness and yield of brussels sprouts could be manipulated by modified transplant production techniques. We examined the effects of variations in seeding date and seeding method as well as the use of row covers over the seedbed.