The ability of the Arundo donax crop to compete with weeds in central Spain over two growing cycles.
Nowadays there is extensive literature dealing with the cultivation of Arundo donax L. for biomass and bio-based compounds. Several agronomic aspects have been addressed while others, such as the need for weed control in the A. donax crop, have been barely investigated. In this work, the objective was to study the effect of weed competition on the A. donax crop in a Mediterranean environment over two growing cycles: the establishment year and the first maturity year of the crop. Weed diversity, weed abundance, plant traits and crop yield were determined in a field experiment with three treatments: no weed removal, weed removal in May and weed removal in June. The presence of alien species of genus Conyza Lessing was recorded throughout the field experiment. Weeds were detrimental to the A. donax crop in the two harvests under study despite the fact that A. donax competition increased from the first to the second growing cycle. In this study, the yield loss was estimated at 55% in the first harvest and decreased to 36% in the second one, showing higher A. donax competition. The results showed that weed removal should not be delayed until June for higher biomass yield.