Seed Electrolyte Loss and Resistance to Fusarium Root Rot of Peas. John M. Kraft, Research Plant Pathologist, Vegetable and Forage Crops Production, Agricultural Research Service, U.S. Department of Agriculture, Prosser, WA 99350. Plant Dis. 70:743-745. Accepted for publication 28 February 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-743.

Resistance in peas to Fusarium root rot, caused by Fusarium solani f. sp. pisi, is evidenced by lower disease indices and higher fresh weights of plant tops and roots of resistant lines than of susceptible pea lines. Seed of three Fusarium-resistant USDA pea breeding lines (RR-1178, 75-786, and 84-1780) and the susceptible cultivar, Dark Skin Perfection, were stressed by methanol or high humidity and temperature. The relationship between emergence, disease index, fresh weights of plant tops and roots, and flow of electric current through leachates from individual seeds, a measure of electrolyte loss, was calculated by regression analysis on individual seeds and seedlings. Physiological aging (6 days at 35 ± 1 C and 100% relative humidity) slightly increased loss of seed electrolytes during imbibition but did not significantly decrease the level of resistance inherent in all three test lines. However, the methanol stress test significantly increased loss of seed electrolytes with corresponding decrease in resistance to Fusarium root rot. In addition, F. solani f. sp. pisi sporulated more profusely in leachates from methanol-treated seed of resistant lines than in leachates from the control or physiologically aged seed.