FLOWERING OF GYPSOPHILA PANICULATA CV. BRISTOL FAIRY IN RELATION TO IRRADIANCE

Low levels of photosynthetically active radiation (PAR) in winter daylight at northern latitudes (45°N) present an obstacle to year-round greenhouse production of Gypsophila paniculata cv. ‘Bristol Fairy’. Supplemental PPF (93 μmol s^-1m^-2 supplied from high pressure sodium lamps from 2000-0700 h each day) applied for 42 or 63 days to plants, enhanced flowering and vegetative growth in crops grown between September and February (fall) and January and June (spring).

In a second experiment, plants were grown in growth chambers at either 8.8 (HPAR) or 3.2 (LPAR) Mol m^-2 day (24 hour irradiance). At 14-day intervals plants were transferred from HPAR to LPAR chambers, and vice versa.
Flower buds were formed first on plants which received between 500 and 550 Mol m^-2 during the first 76 days in treatments.
Thereafter, buds were initiated within 8 to 10 days irrespective of cumulative PAR. Yield of flowers and vegetative plant parts increased with cumulative PAR up to about 745 Mol m^-2 received over a 115-day period.
Higher irradiances during early development were most effective in improving yield.

Symposium on the Development of New Floricultural Crops, XXII IHC

Peter R. Hicklenton

https://doi.org/10.17660/ActaHortic.1987.205.16