Biomass flow and herbage net accumulation rate in Mombaca Grass under different heights

Abstract

In a grazing simulation study in 5 x 4m plots, the leaf elongation rate, the culm elongation rate, the leaf senescence rate, the tiller density/size ratio, the leaf area index, the photosynthetically active radiation interception, and the leaf blade and total herbage production and net accumulation rates were estimated in Panicum maximum cv. Mombaca grass weekly cut to the following target heights: 25; 50; 75; 100 and 125cm. There was a linear positive effect of the target height on the leaf elongation and senescence rates. A quadratic with minimum point effect of the target height on the culm elongation rate was observed, which indicates that the canopy height management can control this process. The lower leaf and culm elongation rates on the canopies maintained under lower target heights tended to be compensated by a higher tiller population density, characterizing the tiller size/density compensation phenomena. The leaf area index increased linearly with the target height elevation, whereas the photosythetically active radiation showed an asymptotic response. The herbage production and net accumulation rates increased with the target height elevation, whereas the leaf net accumulation rate increased up to the 75cm target height, when stabilized, which is the maximum recommended management canopy height.