Clone placement across the gradient and phenotyping
After young leaf tissue was collected from plants in the greenhouse, the
plants remained in the greenhouse under ideal conditions allowing them
to grow rapidly. One cloned ramet from each of the available genets was
then moved to each of the following locations within the regions the
seed was sourced from: 1. breeding plots in Salina, KS at The Land
Institute (West), 2. Prairie Park Nature Center, Lawrence, KS (Central),
3. research plots at the ISU horticulture center in Normal, Illinois
(East), and 4. Land Institute Crop Protection Ecology greenhouse (backup
site to conserve genets in a disease and insect free state). The pots
remained undisturbed at each site for two years, 2020 and 2021 except
the Central site cloned plants, which, in May 2021, were moved from the
Prairie Park Nature Center to the Perennial Agriculture Project field
station, approximately, 6 miles away. The clones received occasional
watering in each site to promote disease growth and avoid plant death
due to the above ground pots drying out.
In 2020 and 2021, disease scores and insect herbivory damage were
recorded on each of the clones in all 3 sites. Data was collected during
their flowering period, between the months of July and September.
Diseases were recorded according to methods in Cassetta et al., 2023.
Briefly, leaf rust severity was quantified by visually assessing the
total percentage of leaf area affected (0-100%) using the rust scale
described by Turner, et al. (2018). Similarly, stem rust severity was
recorded as the total percentage of the stems covered in rust (0-100%).
Leaf blotch was quantified by assessing the total percentage of leaf
area affected (0-100%). Silphium clear vein was rated on a 0-10 scale
based on symptoms observed on the entire plant including: leaf
distortion (narrow width, curled, toothed, twisted, or pinched tips),
and twisted meristem symptoms. Leaf herbivory scores were collected by
quantifying the percentage of total leaves with evidence of insect
herbivore (mining, sucking, chewing) damage (0-100%).