ISHS Acta Horticulturae 248: International Symposium on Models for Plant Growth, Environmental Control and Farm Management in Protected Cultivation
SIMULATION OF PLANT GROWTH BASED ON METHODS OF PLANT GROWTH ANALYSIS EXEMPLARY FOR RADISH |
| Author: | E. Lederle |
| Abstract:
For dynamic modelling quantification of the plant reactions to the growth factors is necessary in consideration of the plant age. The functional approach of plant growth analysis must be used for separating the effect of ontogenetic drift and the one of medium-term climatic fluctuations. As growth functions (equation 1 and 2) and the In-transformation of these ones do not meet all requirements, especially the exact description of the whole growth period (tab. 1), a compound function had to be developed. Using equation 1 the fit of untransformed data was connected with the fit of transformed data as a function of time (equation 3, tab. 1). Instantaneous values of growth components like Absolute Growth Rates (G), Relative Growth Rate (RGR), Net Assimilation Rate (NAR), Leaf Area Ratio (LAR) and the ratio of Leaf Weight and Tuber Weight (LW/TW) were derived from function 3. Marked points like maxima of growth components indicate changes in the metabilism of plants. They are used to divide growth period in physiological founded domains (growth phases) and they are compared with formal weight classes (fig. 1 and 2). Up to now it is impossible to describe physiological age in a functional way. Following from the assumption of constant values of RGR, NAR and LAR within the growth phases the continuous process of age is described in a stepwise manner (fig. 3). The central relationship "RGR=NARxLAR" takes into account that dry matter gain depends on photosynthesis and morphogenesis and that the reaction of these two components on climatic conditions may be different. The assumption of constant RGR values in growth phases implies an exponential gain of dry matter and the daily weight (Wn) can be calculated after the equation Wn = Wn 1 exp (RGR). Daily RGR values are determined by the age, equivalent to the level of RGR values in growth phases, and by the reaction of RGR to daily mean values of radiation and temperature derived from response surfaces. | |
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