Estimating herbage and leaf utilization in bahiagrass (Paspalum notatum Flugge) swards from height measurements

摘要

This study developed empirical mathematical models for estimating utilization in herbage mass (U_M) and leaf (lamina) mass (U_L) from height measurements, using data from bahiagrass (Paspalum notatum Flugge) swards subjected to different cutting heights and intervals and nitrogen fertilizer rates. The models employed utilization in sward height (U_H) as a primary predictor, and incorporated pre-defoliation height of sward (H_(pre)) as an additional predictor. Validation of the models with independent data sets showed that agreement between estimated and measured utilization was good for U_M (R~2 = 0.848, RMSE = 0.048), but not for U_L (R~2 = 0.840, RMSE = 0.101). The relatively poor predictive ability of the U_L model was partially attributed to the changes in the growth form (vertical distribution pattern of leaves) of plants subjected to a low defoliation height. The model for U_M is of potential value for estimating utilization in herbage mass in bahiagrass swards from height measurements, whereas the model for U_L needs further modification to improve its predictive ability.