VIEW ARTICLE

Ecology and Epidemiology

Relation of Carbon Loss from Sclerotia of Sclerotium rolfsii During Incubation in Soil to Decreased Germinability and Pathogenic Aggressiveness. M. Hyakumachi, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824, Present address: 1-1 Yanagido, Gifu University, Faculty of Agriculture, Gifu 501-11, Japan; J. L. Lockwood, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 79:1059-1063. Accepted for publication 5 June 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-1059.

Endogenous carbon from ¹⁴C-labeled sclerotia of Sclerotium rolfsii was progressively lost during 50 days of incubation in soil at ? _m = –10 mbar. The ¹⁴C loss was mainly accounted for as residual ¹⁴C in the soil (4.1–9.3% of the total label) and as ¹⁴CO₂ evolved from the soil (26.0–38.4% of the total label). ¹⁴CO₂ accounted for 45.9–88.4% of the total ¹⁴C loss, and sclerotial respiration was estimated to account for 42.2–77.2% of the ¹⁴C loss during the same incubation time. Sclerotia incubated in soil became dependent on nutrients for germination and lost viability when the ¹⁴C loss reached approximately 20 and 40%, respectively. Radish seedlings inoculated with sclerotia that had lost more than 20% of their ¹⁴C had significantly longer shoots than seedlings inoculated with nonincubated sclerotia.