Rooted cuttings of chrysanthemum were obtained from a commercial propagator (Fides Goldstock Breeding, Maasland, The Netherlands), and planted at 32, 48 or 64 plants m±2 in each compartment (plots randomized). Plants were grown by single stem on four or eightparallel soil beds (1.125.m wide and 10.25.m length per bed, a border soil bed was always present on both sides of the experimental soil beds). All beds had a movable wire netting (mesh size: 0.125.m 3 0.125.m) system, consisting of a frame which included the heating pipes,