The influence of temperature, irradiance, photoperiod and growth retardants on growth and flowering of Angelonia angustifolia Angel Mist series was evaluated. When temperature was increased from 15 to 30 °C, time to visible bud and time to flower decreased in a quadratic manner but total plant height and flower stem dry weight increased linearly. As irradiance increased, time to flower, time to visible bud, and height decreased quadratically. Changes in photoperiod had no effect on growth or flowering, suggesting that A. angustifolia is a day-neutral species with regards to height and flowering time. Daminozide, ancymidol, and paclobutrazol resulted in significant reduction of plant height compared with control plants but did not influence flowering time. Chemical names used: K-cyclopropyl-K-(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide); K-[(4-chlorophenyl)methyl]-K-(1,1-dimethyethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Amanda Miller and Allan M. Armitage
Amanda M. Miller, James M. Garner, and Allan M. Armitage
Five cultivars of the Angel Mist series of Angelonia angustifolia L. were evaluated in the Univ. of Georgia New Crop Program to determine the influence of temperature, irradiance, and photoperiod on crop growth and flowering. When the temperature was increased from 15 to 30 °C, days to visible bud and days to flower significantly decreased while height of flowers, vegetative height, and total height significantly increased. As irradiance increased, plant growth increased but little influence on flowering time was observed. Angelonia angustifolia appears to be a day-neutral plant with respect to flowering. The influence on growth regulators will also be discussed.
Amanda M. Miller, Marc W. van Iersel, and Allan M. Armitage
Light and temperature responses of whole-plant CO2 exchange were determined for two cultivars of Angelonia angustifolia Benth., `AngelMist Purple Stripe' and `AngelMist Deep Plum'. Whole crop net photosynthesis (Pnet) of `AngelMist Purple Stripe' and `AngelMist Deep Plum' were measured at eight temperatures, ranging from 17 to 42 °C. Pnet for both cultivars increased from 17 to ≈20 °C, and then decreased as temperature increased further. Optimal temperatures for Pnet of `AngelMist Purple Stripe' and `AngelMist Deep Plum' were 20.8 and 19.8 °C, respectively. There was no significant difference between the two cultivars, irrespective of temperature. The Q10 (the relative increase with a 10 °C increase in temperature) for Pnet of both cultivars decreased over the entire temperature range. Dark respiration (Rdark) of both cultivars showed a similar linear increase as temperature increased. As photosynthetic photon flux (PPF) increased from 0 to 600 μmol·m-2·s-1, Pnet of both cultivars increased. Light saturation was not yet reached at 600 μmol·m-2·s-1. The light compensation point occurred at 69 μmol·m-2·s-1 for `AngelMist Purple Stripe' and at 89 μmol·m-2·s-1 for `AngelMist Deep Plum'. The lower light saturation point of `AngelMist Purple Stripe' was the result of a higher quantum yield (0.037 mol·mol-1 for `AngelMist Purple Stripe' and 0.026 mol·mol-1 for `AngelMist Deep Plum'). The difference in quantum yield between the two cultivars may explain the faster growth habit of `AngelMist Purple Stripe'.