ISHS Acta Horticulturae 580: IV International ISHS Symposium on Artificial Lighting
DEVELOPMENT AND FLOWERING OF PETUNIA GROWN IN A FAR-RED DEFICIENT LIGHT ENVIRONMENT |
| Authors: | H.H. Kim, R.D. Heins, W.H. Carlson |
| Keywords: | Petunia x hybrida, far-red filter, narrow band red:far-red ratio, broad band red:far-red ratio |
| Abstract:
Far-red (FR) light promotes stem extension in many species and is required for uniform and rapid flowering of many long-day plants (LDP). Stem extension and flowering of the LDP Petunia xhybrida were determined for plants grown in a far-red deficient (FRd) environment. Four petunia cultivars, ‘Priscilla’, ‘Purple Sunspot’, ‘Blue’, and ‘Blue Vein’ were grown in the FRd environment created by filtering sunlight through a FR filter. The four light-quality treatments were 1) no filter (control), 2) an experimental FR filter (FRd), 3) a neutral-density shading material transmitting a photosynthetic photon flux (PPF) similar in intensity to that of the FR filter (N filter), and 4) same as treatment 2 but with the addition of high pressure sodium (HPS) light at 50 μmol m-2 s-1 supplied under the FR filter (FRd+HPS). Plants in 84-cell trays were grown for 2 weeks under the four light-quality treatments. The plants were then transplanted to 10-cm pots and grown for 8 weeks under natural sunlight with 77 μmol m-2 s-1 supplemental HPS light. After the 2-week treatment, growth in height under the FRd was suppressed in ‘Priscilla’, ‘Purple Sunspot’, ‘Blue’, and ‘Blue Vein’ by 40%, 51%, 73%, and 48%, respectively. Growth in height under the N filter was promoted in ‘Priscilla’ (by 38%), but was not significantly different from the control plants for ‘Purple Sunspot’, ‘Blue’ and ‘Blue Vein’. Growth in height under the FRd+HPS was suppressed in ‘Priscilla’, ‘Purple Sunspot’, ‘Blue’, and ‘Blue Vein’ by 11%, 27%, 37%, and 28%, respectively, and compared to the control plants, flowering under the FRd filter was delayed by 7, 10, 11, and 13 days, respectively. Compared to control plants, flowering of plants grown under the N filter and FRd+HPS treatments was delayed only in two cultivars (by 8 to 12 days) and one cultivar (by 8 days). Overall, plants grown under the FRd were compact but flowering after transplant was delayed. We are conducting additional studies in an attempt to produce compact transplants using the FR filter, but without a delay in flowering. | |
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