Methods
Study Name: Alternaria dauci tolerance evaluation Experiment Type: Field Exp. Design: RB Exp. Location: Sanford Soil class/texture: Myakka fine sand. Investigator: James Strandberg. Comment: Seeds of 'Apollo' were planted for infection rows which consisted of the outside rows and every third row within the plot area artificially inoculated on two occasions with spores of Alternaria dauci (Strandberg, 1987). Rows were 280 ft. long on 30 inch centers. Plants were hand-thinned to 1-2 inches per row. Plant Introduction accessions were hand planted 1-2 days later and also thinned as needed. Thus, accessions were infected by natural inoculum spread from the adjacent infection rows. Each accession plot consisted of a single row 15 ft. long. After disease symptoms appeared, accessions sampled weekly by collecting 20 leaves at random from each plot and compared with an Alternaria leaf blight damage key and classified as to the percent of leaf area damaged (Strandberg 1988). The average percent leaf area damaged (LAD) on each 20-leaf sample was calculated weekly. Subjective rating from 0 = no visible disease damage; 1 = few lesions mostly on older leaves; 2 = numerous lesions on older leaves, scattered on younger leaves; 3 = abundant lesions, some defoliation and leaf damage; 4 = abundant lesions, moderate leaf damage, defoliation; 5 = severe leaf damage and defoliation. Plots clearly judged to be intermediate between two classes were assigned fractional values in increments of 0.5 units (a plot intermediate between 3 and 4 was assigned a 3.5). For some very susceptible lines, subjective ratings were made before the end of the experiment because the plants were rapidly being killed by the disease. A special category called persistent leaves was used to describe lines where numerous leaves remained alive and persisted for several days or weeks in spite of high disease damage ratings which may express useful levels of disease tolerance.
Daucus descriptor data recorded from observation planting at the NCRPIS farm (42 degrees 3 minutes N latitude 93 degrees 30 minutes W longitude).
Daucus descriptor data recorded from observation planting Field W-1 at the NCRPIS farm (42 degrees 3 minutes N latitude 93 degrees 30 minutes W longitude).
Daucus descriptor data recorded from observation planting Field N-3 at the NCRPIS farm (42 degrees 3 minutes N latitude 93 degrees 30 minutes W longitude).
Daucus descriptor data recorded from observation planting Field N-10 at the NCRPIS farm (42 degrees 0 minutes N latitude 93 degrees 30 minutes W longitude).
Daucus direct seeded into two 4-foot rows 8 inches apart in NCRPIS Farm Greenhouse-3 sandbox measuring 8’ x 4’ x 2’ (l x w x h) and filled to 20-inch depth with sand. Sandbox was watered as needed and seedlings fertilized with a liquid fertilizer twice weekly. Seedlings were thinned to 2 to 3 -inch spacing. Roots were carefully dug from the sand for notes/images after two to four months (or sooner if plants began to bolt). Root characterization notes/images were recorded on plants between 50 and 130 days after planting (DAP); average was 92 DAP. Notes/images recorded on 10 roots per accession.
Daucus descriptor data recorded from observation planting in Greenhouse 3 in large pots filled with soil at the NCRPIS farm (42 degerees 3 minutes N latitude 93 degrees 30 minutes W longitude). Seeds of Daucus accession direct seeded into sandbox 8 feet x 4 feet x 24 inches (l x w x h); watered as needed, fertlized with standard liquid fertilzer weekly. Notes recorded ~ 100 days after planting on 10 roots.
Digital image of whole plant, population, or composite plant images taken by NCRPIS personnel.
Digital image of leaf or leaves taken by NCRPIS personnel.
Digital image of umbel take by NCRPIS personnel.
Dgital image of root taken by NCRPIS personnel.
Digital image of root transverse section taken by NCRPIS personnel.
Digital image of seed or seeds captured via microscope camera, taken by NCRPIS personnel.
Scanned image of leaf or leaves taken by NCRPIS personnel.
Scanned image of umbel taken by NCRPIS personnel.
Scanned image of root taken by NCRPIS personnel.
Scanned image of root transverse section taken by NCRPIS personnel.
Scanned image of seed or seeds taken by NCRPIS personnel.
This is the generic evaluation method that can be used for transferring hundred seed weights from the prod.nc7iv table to the prod.ob table. The prod.ob table is where the values for the descriptors are stored.