Resiliance in Forages and Grazinglands: Tropical and Subtropical Regions.

Approximately 50% of the cattle herd in the world is located in tropical and subtropical regions. Warm-season C₄ grasses are the main source of nutrients for livestock in these regions, primarily due to their adaptability to a wide range of defoliation regimes and environmental conditions. A great proportion of livestock production regions in the world rely predominantly on warm-season grass species, such as Cynodon, Brachiaria, and Cenchrus. Because of the different decarboxylation enzymes, these warm-season grass subtypes may be more adapted to specific regions within tropical and subtropical areas. In addition, differences in anatomical and morphological characteristics can also affect the adaptability of these species to management practices. Apical meristem in some warm-season grasses are generally less susceptible to defoliation because of their basal location within the plant; however, other factors such as biochemical and morphological characteristics will also affect the persistence of warm-season grass species. There has been a growing concern worldwide about the invasiveness potential of some warm-season grasses. Extensive evaluation under controlled conditions should be conducted before the release and propagation of new warm-season grass cultivar to determine its resilience and invasiveness potential. Warm-season grass breeding programs have historically focused on increasing herbage accumulation and nutritive value; however, much less attention has been given to persistence and adaptability of new warm-season grass releases to different locations, environmental conditions, and management practices. Recent research evidences demonstrated selection based on herbage accumulation and nutritive value may result in decreased persistence of new warm-season grasses cultivars primarily due to detrimental changes in morphological characteristics, such as growth habit, leaf:stem ratio, and root and rhizomes mass and composition. To respond to production and ecological challenges, a more holistic approach should be considered when selecting and managing warm-season forages.