Effect of Nitrate Distribution in Melilotus infesta Guss. On Resistance to the Sweetclover Weevil

The purpose of this research was to determine the distribution of nitrate in various plant parts and at various ages in Melilotus. infesta and to relate the role of nitrate in this species to the feeding resistance to the sweetclover weevil.A more complete understanding of the effect of nitrate in the feeding response will provide additional information about the nature of resistance in M. infesta to theweevil. The line of Melilotus infesta Guss. used in all experiments was represented by Nebraska Strain M 70.The weevil susceptible species of Melilotus was represented by M. officinalis var. Goldtop. Sweetclover root disks used in bioassays were obtained from branch roots of field-grown. M. alba var. Evergreen. All fresh plant material used in the various studies was grown in the greenhouse.Ten plants were randomly selected from 150 plants for each species.These plants were approximately six weeks of age and had the same total number of leaves on a single stem.The plant stems were cut off just below the cotyledons.The average plant height was 11.5 cm. The stems of the plants were also tested for their dry weight determinations and nitrate assays. The leaves of the entire plants were removed and sorted according to corresponding leaf ages. The leaves were then analyzed for nitrate assay and dry weight determination.Ten samples of the weevil resistant sweetclover species were extracted in the same manner and analyzed for comparison. Advisor: George R. Manglit