Analysis of the Growth Kinetics of Dactylis glomerata L. in the Vegetative Phase

This study analyzes the growth kinetics of Dactylis glomerataL. in the vegetative phase of growth on the basis of a modeldifferentiating between two components of plant material. Thefirst component, M₁, is related to the processes of productionof dry weight while the second component, M₂, is not. Two kineticphases are considered. In the initial phase, the plant has onlythe M₁ component; production of dry weight follows an autocatalyticprocess and growth is exponential. In the second phase, theM₂ component develops, introducing a decrease in the specificgrowth rate. An attempt is made to express the variation ofthe percentage of the two components during growth using a sphericalmodel. The M₁ component, associated with the environmental interface,is considered to be the surface component, as opposed to thecore component, M₂. It is assumed that at the end of the initialphase the surface component has a definite constitution whichwill not be modified in the following course of growth. Underthis assumption, a kinetic equation is derived, M(t), whichis found to tend to a time power function, t₂, for high dry-weightvalues. For the two phases, the kinetic equations are describedby the same set of three parameters, k₀ M₀and t₀; k₀ is thespecific growth rate of the initial exponential phase and M₀is the value of dry weight at the transition between the twophases which appears at time t₀. The theoretical growth functiongives a satisfactory description of the experimental growthcurves measured at three temperatures (10, 17 and 25 °C),in a controlled environment. Dactylis glomerata L., vegetative phase, growth kinetics, growth function, mechanistic model