Selection strategies to reduce invasive potential in introduced plants

The crop domestication process is examined from plant collection to product release for various junctures at which deliberate breeding, selection, and crop transformation may occur to prevent invasive potential. Four primary juncture opportunities for research on techniques and development of selection procedures for non-invasiveness include: The Plant Exploration Phase, Initial Trial Phase, Fast-Tracking Phase, Selection and Improvement Phase. Avoiding the collection of germplasm that appears weedy during plant exploration is an obvious, yet cost-effective way to reduce invasiveness in a selection program. During initial trials, comparing genotypic differences in traits related to invasiveness should allow plant breeders to identify cultivars that pose the least risk before undertaking comprehensive field trials. Genotypes with high commercial value, considered candidates for "fast-tracking", should only advance quickly to product release if they exhibit a minimum level of invasive risk, i.e., species with low dispersal capacity and that have little potential to impact ecosystems. Fast-growing taxa, those with high seed production, ones likely to be rapidly dispersed by wind, animals, water or people, and others that can significantly alter nutrient or light levels are examples of species that should not be "fast-tracked". Field trials that have typically been used to evaluate performance of genotypes across a broad range of cultivated environmental conditions need to be expanded to adequately evaluate invasive potential during the selection and improvement phase. Testing in environments that mimic conditions where introductions could naturalize is crucial, as are evaluations of competition with indigenous species. The time and resource investment needed to conduct adequate trials at this stage is potentially very high; more research is needed to ensure the trials conducted are targeting important information gaps for decision-making. Additional research is also needed to develop modeling approaches that effectively forecast long-term dynamics of introductions and to assist in developing field testing priorities. Minimizing invasive potential could significantly reduce introductions that cause inadvertent damage to landscapes and ecosystems. The strategy proposed here will require further development, especially in the context of understanding and assessing risks of pre- and post-release strategies for minimizing damage from invasive species.