Tiller dynamics and growth of Rhodes grass after defoliation: A model named TILDYN

The dynamics in tiller population and dry-matter accumulation of a grass sward, cut at different time intervals, was compared with a descriptive simulation model. The model was validated against experimental data of tiller number, and dry-matter accumulation for irrigated cv. Katambora Rhodes grass (Chloris gayana Kunth), cut at intervals of 1, 2, 3 or 4 weeks. The model predicted that the initial rate of regrowth following long cutting intervals was much slower than the regrowth following short cutting intervals. The simulations also showed that relatively high dry-matter yields alternated with relatively low dry-matter yields when the interval between cuttings was long. These results were in reasonable agreement with the measured values. The fluctuation in the number of tillers and dry-matter yield was attributed mainly to the formation of culmed-vegetative tillers, common to Rhodes grass at an early stage of development, which renders them incapable of regrowth after defoliation.