vegetative storage, carbohydrates, mesquite tree, herbivory.
Objective: To evaluate the impact of extensive grazing in the accumulation of soluble sugars in Prosopis laevigata trees, whose leaves and fruits are directly consumed by cattle.
Design/Methodology/Approach: The ejido Emiliano Zapata in Durango was the study area. Stem and root samples were collected from a stand of extensive grazing and a stand without cattle. The sampling was carried out in three growth stages: March (flowering), June (fruition), and October (leaf fall). The samples were frozen in liquid nitrogen and were lyophilized. Afterwards, they were ground and 10 mg of dry matter were weighted in microtubes. The total soluble sugars (TSS) concentration was determined following the Van Handel methodology, using a spectrophotometer at 625 nm. The statistical analysis was carried out using an ANOVA and the Tukey’s test.
Results: In March, the grazing area had lower TSS concentrations during regrowth than the area without grazing, both at root and stem levels.
Study Limitations/Implications: The intensity of grazing and the pasture rotation should be regulated to favor carbohydrate accumulation in trees, which is required for the formation of the meristematic tissues.
Finding/Conclusions: Extensive grazing has an impact on the synthesis and accumulation of TSS in mesquite trees. Therefore, the consumption of branches, leaves, and fruits decreases TSS concentrations in the stem and the root.