The effect of time of seedling emergence and density on the marketable yield of spring cabbage

Abstract

The individual weights of spring cabbage shoots at harvest are directly affected by the relative times of seedling emergence; a spread of only 5-10 d accounted for 46% of the weight variation at approximately 65 d after sowing. Also, competitive interactions between plants derived from early and late emerging seedlings were evident at densities lower than those used in commerce, and these competitive interactions intensified with increasing plant density. A model described by Benjamin (1988) was fitted to some of these data and then used to predict the yields of cabbages in various weight grades in an independent data set. There were some systematic deviations between predicted and observed yields but little evidence of this deviation for yields in the marketable grade of 150-250 g.