ISHS Acta Horticulturae 435: II Workshop on Environmental Regulation of Plant Morphogenesis
THE EFFECTS OF TEMPERATURE AND PHOTOPERIOD ON THE FLOWERING AND MORPHOLOGY OF TRAILING PETUNIAS |
| Authors: | S.R. Adams, S. Pearson, P. Hadley |
| Abstract:
Trailing petunias (Sylvana; Malve and White) were grown in a linear array of glasshouse compartments with heating set points of 6, 10, 14, 18, 22 and 26°C. Within each compartment light tight photoperiod chambers were used to provide 8, 11, 14 and 17hr photoperiods. Half of the plants were pinched at the start of the experiment, while the remainder were left unpinched. Earliest flowering occured with pinched plants of cv. Malve (after 33 days) grown at the highest temperature and longest photoperiod. Cool temperatures and short days delayed time to flowering. Shorter photoperiods delayed flowering such that cv. Malve grown at 18°C and 17hd-1 flowered after 40 days compared to 97 days at 8hd-1. Plants grown in long days had a different morphology to those in the short day treatments. Under long days, branch number was reduced and the primary axis became elongated with an upright habit. Under short-days, the plants tended initially to have a compact habit and later trailed, this was particularly apparent at the warmer temperatures (>14°C). Pinching resulted in shorter plants, with increased branching, and higher ornamental value. The results are discussed in terms of the potential for manipulating plant morphology via the control of temperature and photoperiod. | |
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