Effect of light intensity, plant density, and flower bud removal on the flower size and number in cut chrysanthemum

Flower size and number of flowers per plant are important external quality aspects in cut chrysanthemum. The present work is conducted in a glasshouse and aims at investigating how these quality aspects can be predicted. To evaluate individual flower size, different levels of supplementary lighting (control and assimilation light), plant density (32, 48 and 64 plants m(-2)) and lateral flower bud removal (leaving 1 flower, 4 flowers and control) were applied. To analyse the effect of assimilate supply on number of flowers per plant, three light intensities (no shade control, 65% light, and 45% light) where combined with three plant densities (32, 64, and 80 plants m(-2)). Individual flower size was negatively influenced by competition for assimilates in the treatments with a fixed number of flowers per plant (1 or 4 flowers). In such treatments, plants grown under no supplementary assimilation light, higher plant density, or with higher number of flowers per plant resulted in significantly lower individual flower dry mass and area. However, when no lateral flower buds were removed (control), higher assimilate supply resulted in more flowers rather than in larger flowers. Number of flowers per plant (including flower buds) showed a positive linear increase with total dry mass per plant. The combination of 32 plants m(-2) and no shade resulted in the highest number of flowers per plant (33 flowers) in contrast with 80 plants m-2 and 45% light intensity (only 9 flowers).