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%).