FACTORS CONTRIBUTING TO THE DELAY IN THE FLOWERING OF POT CHRYSANTHEMUMS GROWN IN PEAT-SAND SUBSTRATES
Deficiencies of copper and iron resulted in delays in flowering extending to 10 days for both winter and summer grown crops.
Treatments resulting in high nitrogen levels in the leaf tissue gave delays in winter crops of up to 28 days with the variety 'Dark Red Star' and 12 days with 'Golden Princess Anne'. Each increase of 1% in the nitrogen in the leaves of 'Golden Princess Anne' delayed flowering by 4 days. The delay in the flowering of plants grown with a capillary system of irrigation has been attributed to the increase in the nitrogen content of the plant resulting from this system of irrigation rather than to low matric potentials. High levels of potassium in the plant tissue did not materially mitigate the adverse effects of high nitrogen.
Increasing the air capacity of the substrate was also beneficial in the case of varieties which are normally susceptible to delayed winter flowering.
The effect of high nitrogen in delaying flowering was not apparent under summer conditions of high solar radiation flux density.