Background:

Management strategies may affect plant growth and herbage characteristics. Thus, understanding their impact may help to define appropriate management.

Objective:

To evaluate the effect of different defoliation intensities and frequencies on structural characteristics, biomass components, and the potential use of NDVI (normalized difference vegetation index) in pastures with Megathyrsus maximus cv. BRS Tamani.

Methods:

A randomized block design in a 2x3 factorial arrangement was adopted, with two defoliation frequencies (85 and 95% interception of photosynthetically active radiation (IPAR) and three defoliation intensities (residual leaf area index (LAIr) of 0.8, 1.3, and 1.8).

Results:

The frequency of defoliation affected the pre-defoliation leaf area index, height, total harvestable forage biomass (HTFB), and harvestable leaf blade (HGLB), with higher values for pastures managed at 95% IPAR. The effect of defoliation intensity was observed for HTFB and HGLB, where pastures with lower LAIr presented higher biomass values. Pastures managed at 95% IPAR and higher LAIr reached the saturation level of the NDVI more quickly. Pastures managed under the combination of 95% IPAR and LAIr of 0.8 showed higher production of harvestable green stem biomass and harvestable dead forage biomass. The combination of 95% IPAR with LAIr of 0.8 or 1.8 enabled a higher number of new live leaves when compared to pastures with 85% IPAR.

Conclusion:

Tamani grass must be managed with a defoliation frequency of 95% interception of photosynthetically active radiation, maintaining a residual leaf area index between 0.8 and 1.3.

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