2 chloroethyl phosphonic acid and flower initiation by chrysanthemum morifolium in short days and in long days

Cockshull, K.E.; Horridge, J.S.

Journal of Horticultural Science 53(2): 85-90


Accession: 004534664

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2-Chloroethylphosphonic acid (CEPA) was applied as a foliar spray to C. morifolium 'Polaris' grown either in long days throughout or transferred to short days at the time of treatment. Flower initiation was delayed and more leaves were formed below the terminal flower bud when plants were sprayed with either 100 or 1000 ppm at the onset of short days. The delay in flower initiation caused by long days was increased by the application of CEPA. The numbers of additional leaves formed in response to CEPA were similar in both day lengths, indicating that this delaying effect is additive to that of long days and probably independent of it. Five applications of 1000 ppm at weekly intervals were more effective than 1 application and delayed flower initiation in short days by an estimated 122 days. CEPA also increased the rate of leaf initiation and modified apical dominance. The leafiest axillary shoots were produced when CEPA was applied to plants in short days, suggesting that both factors can weaken apical dominance.