J. AMER. SOC. HORT. SCI. 123(3):412-415. 1998.

Diallel Analysis of Resistance in Carrot to Alternaria Leaf Blight

Philipp W. Simon
U.S. Department of Agriculture, Agricultural Research Service, Vegetable Crops Research Unit, Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706

James O. Strandberg
University of Florida, Central Florida Research and Education Center, Apopka, FL 32703

ADDITIONAL INDEX WORDS. Daucus carota, Alternaria dauci

Additional index words. mutagenesis, somaclonal variation

ABSTRACT. Diverse carrot (Daucus carota L.) inbreds were evaluated as young plants in the greenhouse and mature plants in the field for resistance to the pathogena Alternaria dauci (Kühn) Groves and Skolko. Persistence of leaves after infection was the criterion used to estimate disease damage by the pathogen. Partial resistance was identified. A five-parent diallel evaluated for resistance indicated a preponderance of additive variation with some dominant gene action for resistance. Reciprocal cross differences were significant for certain crosses. Responses of most inbreds were useful in predicting resistance in their hybrids, but exceptions to this trend did occur. Field resistance ratings generally correlated well with resistance ratings obtained in greenhouses, even in grower fields where fungicides were applied.

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Received for publication 17 July 1997. Accepted for publication 7 Jan. 1998. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.

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