Date of Award:

5-1975

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Botany

Committee Chair(s)

Orson S. Cannon

Committee

Orson S. Cannon

Committee

Wade G. Dewey

Committee

Arthur H. Holmgrem

Abstract

Rust-infested and uninfested seedlots of 14 safflower (Carthamus tinctorius) entries (4 resistant lines, 4 moderately or fully susceptible lines, and six F1 hybrids from crosses between rust-susceptible females and rust-resistant males), were planted in replicated field trials. The four infested entries resistant to seedling rust incited by Puccinia carthami Cda. exhibited average stand losses of 2.4, 8.4, 18.4, and 27.7%. Stand reduction in the resistant entries was not greater than the inherent compensating ability of the surviving plants; consequently, the yield of these entries was not significantly reduced. Plots from the rusted seedlots of the moderately and fully susceptible entries had stand losses of 54.9, 79.5, 95.4, and 97.6%, and yielded significantly less than plots grown from uninfested seedlots. Stand reduction in these entries exceeded the inherent compensating ability of the surviving plants. Hybrid entries of rusted seedlots showed stand losses of 37.3, 47.4, 94.4, 61.7, 90.1, and 90.5%. Hybrids showed a better inherent compensating ability of surviving plants than pure lines. In the partial hybrid lines the undesirable selfs were eliminated by seedling rust, leaving a population composed of high yielding hybrid plants.

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