ISHS Acta Horticulturae 456: II Modelling Plant Growth, Environmental Control and Farm Management in Protected Cultivation
PREDICTING VARIABILITY IN ANTHESIS OF EASTER LILY (LILIUM LONGIFLORUM THUNB.) POPULATIONS IN RESPONSE TO TEMPERATURE |
| Authors: | P.R. Fisher, R.D. Heins, J.H. Lieth |
| Keywords: | phenology, thermal time, variation, decision-support, Easter lily |
| Abstract:
Most thermal time models for ornamental plant species are deterministic, i.e. they predict the timing of a phenological event (for example anthesis) for the average of a population. In ornamental plant production, the variability and distribution of harvest, in addition to the mean, is important for planning resources (e.g. labor, cooler space, shipping). The objective was to predict the distribution of anthesis dates for a population of Easter lilies (Lilium longiflorum Thunb.). ‘Nellie White’ grade 8/9 Easter lilies were grown at two research greenhouse locations during 1996 and 1997 under a variety of temperature and cooling regimes. The mean and standard deviation in thermal time from visible bud to anthesis was estimated at 792 ± 62°Cd with a base temperature of -4.5°C. The elongation of flower buds over thermal time was quantified using an exponential function, with an R2 of 0.99. As bud length increased, the variability in thermal time to anthesis decreased, i.e. the standard deviation in thermal time to anthesis was negatively correlated with bud length. Combining the model of visible bud to anthesis and the bud elongation function allowed prediction of the distribution of anthesis dates. On a single date, the developmental stage (visible bud, or a particular flower bud length) was recorded for a sample of plants. The combined model was then run for each developmental stage, to predict when each stage would reach anthesis. Predicted anthesis dates for each stage were combined in order to predict the anthesis distribution for the entire population. | |
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