Mechanical Harvesting Assessment of Guayule at Different Growth Stages for Sustainable Rubber Production

Guayule (Parthenium argentatum Gray) represents a highly promising non-food industrial crop for the production of natural rubber and bio-based co-products, particularly suited for arid and semi-arid Mediterranean environments. However, the lack of dedicated, large-scale harvesting mechanization systems currently acts as a severe bottleneck for its commercial supply chain development. This study evaluates the field performance and technical feasibility of a prototype cut-and-load harvesting system specifically adapted from conventional forage machinery to manage the high resin and latex contents that traditionally induce clogging. Field trials compared three different crop maturity types: 5-year-old plants (first harvesting cycle), 2-year-old plants (second harvesting cycle), and 1-year-old plants (second harvesting cycle) . The monitored variables included collected biomass yield, working field capacity, machine efficiency, and the frequency of clogging events. Results demonstrated that mechanical harvesting parameters were not significantly affected by crop maturity or harvesting cycle. The prototype maintained a stable field capacity (0.79 to 0.82 ha h.¹) and a high machine working efficiency (85.7% to 86.3%) across all treatments, while successfully mitigating resin-induced downtime (0.6 to 0.7 clogs h.¹). These findings confirm the feasibility of adapting conventional machinery configurations for standardized guayule harvesting, supporting the scale-up of sustainable bio-based agricultural value chains.