Feasibility of assessing vegetative and generative endpoints of crop- and non- crop terrestrial plant species for non-target terrestrial plant (NTTP) regulatory testing under greenhouse conditions

Agriculture is the dominating land-use in the EU member states covering
nearly half of the surface area. Using herbicides to reduce weed
competition in agricultural areas can adversely affect Non-Target
Terrestrial Plants (NTTP) growing in field margins. According to the EFSA
Scientific Opinion on NTTPs an important protection goal is to maintain
the biodiversity of plant species in agricultural areas. EFSA recommends
to include also non-crop species mentioned in OECD guidelines (OECD 208
and 227) in the testing and to assess not only vegetative but also
generative endpoints during the plant life-cycle such as flowering and
seed production. The objectives of this study were to evaluate the
feasibility of assessing generative endpoints of crop and non-crop species
for NTTP regulatory testing under greenhouse conditions and to assess if
generative endpoints are more sensitive than vegetative endpoints. The
experimental design consisted of one control and four herbicide (Atlantis®
WG) application rates, with 6 replicates each. The application rates of
the test substance were the maximum field rate and 30%, 10% and 3% of the
field rate. Biomass, plant height, flowering, seed production as well as
seedling emergence of the F1 generation were assessed. The study shows a
feasible approach to assess vegetative and generative endpoints of (non-)
crops species under greenhouse conditions on the basis of the OECD
guideline 227. The vegetative endpoints plant height and biomass were not
more sensitive if assessed during the generative growth stage when
compared to the vegetative growth stage of the plants. In contrast to
that, the generative endpoint seed production was partly more sensitive in
comparison to the vegetative endpoints biomass and plant height. For
regulatory NTTP studies, 5 or more test substance rates at non-lethal
levels should be tested so to allow the determination of ER10/50 values
for vegetative and generative endpoints.