The effects of crop density on plant growth and variability in cut-flower chrysanthemum (Chrysanthemum morifolium Ramat.)

SummaryThe effects of crop density on chrysanthemum plant yield and variability were studied using two cultivars, Snowdon and Delta, in four experiments (spring, summer, autumn and winter) using fan design layouts of gradually increasing space per plant. Average total fresh weight per plant varied greatly between experiments, but empirical linear regression relationships showed that changes in space per plant gave near proportional changes in weight per plant over the whole range of densities sampled. This suggests that the density responses were essentially mediated by the available light per plant. A simple three-parameter model was developed incorporating the accumulated light integral and this gave an excellent fit to data in all four experiments. The fresh weight of flowers per plant was allometrically related to ``productive'' plant weight which was defined as total plant weight minus a fixed weight not contributing to flower production. The relationships showed that the proportional partitioning of...