EVALUATION OF AN EMPIRICAL AND A SEMI-MECHANISTIC APPROACH TO PREDICT THE IRRADIANCE INTEGRAL REQUIRED FOR GROWTH OF FOLIAGE PLANTS

Two potential approaches for predicting the irradiance integral which is required for growth (i.e. leaf area expansion) of foliage pot plants were presented, i.e. a growth function with the solar irradiance integral as driving variable (empirical approach) and an approach in which plant growth was derived from the upscaling of leaf CO₂ assimilation in time and space (semi-mechanistic approach). Both approaches were evaluated in Ficus benjamina. It was evidenced that a growth function that was parameterised to a winter data set, provided also accurate predictions of leaf area expansion in spring and summer.
The semi-mechanistic approach yielded only moderate estimates of leaf area expansion.
So, within the range of light regimes that were considered in the present study, it can be stated that a growth function which merely includes the information of the irradiance integral, when used in conjunction with meteorological data of solar radiation and the information of the transmission characteristics of the greenhouse, is suitable to predict the irradiance integral required for growth of foliage pot plants and as such to assess to which extent the growth period may be reduced by the application of supplementary lighting.
The inadequacy of the semi-mechanistic approach for practical use of assessing leaf area expansion and therefore also for predicting the growth period, was connected to the high sensitivity of the model predictions to parameters that were presumably badly tuned to the prevailing conditions.

III International Symposium on Artificial Lighting in Horticulture

F. Fredrick, R. Lemeur

Ficus benjamina, Gompertz equation, growth model, growth period, leaf area expansion, supplementary lighting

https://doi.org/10.17660/ActaHortic.1997.418.9