The effect of planting date and plant density on yield and grading of Brussels sprouts

Abstract

SummaryDuring three seasons the effects of planting date and plant density, and their interaction, on marketable yield and grading of Brussels sprouts (Brassica olerácea var. gemmifera) were studied in field experiments. The marketable yield, as an average of three or four successive mechanical harvests, decreased with delay in planting from the end of April–early May to the end of June–early July. Final marketable yield levels varied between 29.4 tonnes per hectare when planting was early, to 17.4 tonnes per hectare when planting was late in the season. A decrease in yield with an increase in plant density from 2.7 to 4.4 plants per m2 was found in only one year. Grading (percentage of buds ã31mm) was not consistently influenced by planting date, but increasing the plant density increased the proportion of small buds. There were no or interactions of only limited importance between the effects of planting date and plant density on yield and grading, indicating that, within one year, for the whole range of planting dates the effects of density on yield and grading are similar. For a high yield of small buds, plant density should be increased and the harvest date delayed. For harvest planning, better use should be made of variation in maturation time between cultivars, rather than of variation in the date of planting. Maturation time within a cultivar can be manipulated by varying the plant density.