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Temporal variation in the chemical composition of Nassella trichotoma (Nees) Hack. ex Arechav. under a defoliation gradient

Andres Garcia , Roberto Distel, Alejandro Loydi

Abstract

Fluctuations in the chemical composition of invasive species can identify windows where grazing implementation con be maximized for improved weed management. Our goal was to determine the chemical composition of N. trichotoma, an aggressive invasive grass species, after being subjected to wither high or low defoliation across a temporal gradient. Plants were subjected to a defoliation gradient, and leaves were harvested over the growing season. All samples were analyzed for Protein Content (PC) and NDF (Neutral Detergent Fiber), ADF (Acid Detergent Fiber) and ADL (Acid Detergent Lignin) content. PC tended to be greater, and NDF and ADF were higher in defoliated plants compared to undefoliated plants. An induced anti-herbivore defense may explain an increase in fiber content in response to defoliation, which would accentuate the low nutritional quality of N. trichotoma and thus its avoidance by cattle. Therefore, efforts should focus on preventing regrowing shoots from losing nutritional quality by integrating control measures, such as fire in early autumn to early spring, intermittent high stocking, and sowing desirable native species. This approach could effectively control N. trichotoma persistence and spread.

RJ24029  Accepted 24 January 2025

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