M. HIRATA and W. PAKIDING

Grassland and Animal Production Division, Faculty of Agriculture, Miyazaki University, Miyazaki, Japan
At the time of the study, WP was a student at the United Graduate School of Agricultural Sciences, Kagoshima University, Japan, being on study leave from Faculty of Animal Husbandry, Hasanuddin University, Indonesia.

Abstract

Dynamics in weight, length and weight per unit length of individual laminae (live and dead) on a tiller were investigated for 2 years in a bahia grass (Paspalum notatum) pasture under cattle grazing. For the youngest fully expanded lamina, its history, mature length and fate were also estimated to evaluate the degree of removal of lamina length through defoliation by animals and detachment as litter fall. Lamina weight per tiller, ranging from 36–200 mg/tiller DM, was high in May–October (late spring to mid-autumn) and low in the other half of the year. The youngest to sixth youngest laminae (L1–L6; usually live laminae) accounted for 62.5–91.0% of the lamina weight per tiller. Weight, length and weight per unit length of laminae (L1–L12) ranged from 0.0–48.0 mg DM, 0–326 mm and 0.035–0.255 mg/mm DM, respectively, often varying with lamina age and season. Variations in lamina weight were largely explained by variations in lamina length, with no consistent contribution by lamina weight per unit length. Laminae lost 16–64% of their mature length through grazing by animals before and immediately after attaining full expansion. In the 2 months after full expansion, they lost an additional 24–79% of mature length through defoliation by animals and detachment as litter fall, with total removal of 88–99%. The study shows how the history and fate of individual laminae on a tiller can be estimated in terms of their appearance and development. This model, in combination with previously developed models for dynamics in tiller density and tiller weight, is useful for simulation studies on canopy dynamics in bahia grass swards.