Invasive Teline monspessulana and Ulex europaeus allelochemicals induce differential responses regarding the growth and physiological performance of two native Chilean tree species

Abstract

Teline monspessulana and Ulex europaeus (Fabaceae) are highly invasive species distributed worldwide. In Chile, both species share a similar distribution area with the native species Quillaja saponaria and Peumus boldus. This research focused on determining the effects caused by the aqueous extracts of the aerial organs of both invaders on the initial growth and photosynthetic performance of the two native tree species. Experiments were established under controlled conditions simulating natural conditions where both invasive and native species coexist. Morphometric variables defining root and aerial development were evaluated. Photosynthetic performance was also evaluated by measuring chlorophyll fluorescence, pigment content, and non-structural carbohydrates. In Q. saponaria seedlings, the growth of aerial and root organs was affected, but the production of photoassimilates increased under allelochemical stress. No damage to the photosynthetic machinery was observed in P. boldus, but its initial growth was notably reduced, possibly compromising its survival when interacting with both invasive species. The results indicated that allelochemicals synthesized by the two invasive species differentially affected the morphophysiological performance of the two native species. In terms of carbon administration, our results indicate that Q. saponaria seedlings probably use the assimilated carbon for biomass and defensive compound production. In contrast, P. boldus seedling growth is more sensitive to allelochemical stress and is seriously compromised, maybe because its metabolism is mainly invested in defensive compounds to deal with invasive species.