Effect of seasonal radiation and daylength shifts on growth and development of spray carnation. 2. Flower initiation.

Abstract

Growth and development of 32 year-round plantings of the spray carnation cv. West Pink were determined. Pinching between March and July resulted in a growth period of about 70 days between pinching and microscopically visible flower initiation. When pinching took place between August and October this period increased linearly to 180 days. When pinching took place in November or later, the growth period until flower initiation decreased with one day for every day pinching was delayed. This resulted in a microscopically visible flower initiation on 7 May in many plantings. At cellular level flower initiation would have occurred in mid-April, i.e. at a daylength of approximately 14 h. Immediately after flower initiation there was an abrupt increase in the shoot extension rate. Frequent measurement of shoot length thus offers a non-destructive method to determine flower initiation. No substantial differences were found between West Pink and the standard carnation cv. White Sim with respect to daylength effects. These results with spray carnations agree fairly well with published year-round data on the total growth period between planting or pinching and flowering of standard carnations. [For part 1 see Netherlands Journal of Agricultural Science (1987) 35 (1), 55-62.] (Abstract retrieved from CAB Abstracts by CABI’s permission)