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Physiology and Biochemistry

Effect of Volatile Compounds, Nutrients, and Source of Sclerotia on Eruptive Sclerotial Germination of Sclerotium rolfsii. Z. K. Punja, Research scientist, Campbell Soup Company (also visiting assistant professor) Department of Plant Pathology, North Carolina State University, Raleigh 27695; S. F. Jenkins(2), and R. G. Grogan(3). (2)Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695; (3)Professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 74:1290-1295. Accepted for publication 29 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1290.

Sclerotia of Sclerotium rolfsii produced on oat kernels in the laboratory were stimulated to germinate eruptively by alcohols and acetaldehyde at levels ranging from 1.6 to 6.1 μl per petri dish. Isopropyl and butyl alcohols were more stimulatory to germination than volatiles evolved from dried and remoistened alfalfa leaf tissue. These compounds increased linear growth rate of the mycelium but did not significantly affect dry weight. The addition of a carbon source, such as 20 mM glucose or sucrose, to Noble water agar inhibited eruptive germination but stimulated hyphal germination. Dry weight loss from sclerotia and leakage of amino compounds and carbohydrates during germination were reduced by glucose. Sclerotia from potato-dextrose agar cultures responded differently to selected alcohols and NaCIO treatment than sclerotia produced on oats in the laboratory or in soil. Differences among these sclerotia in the thickness and composition of the rind and underlying cortical tissue were observed which could in part have accounted for these behavioral differences. Low and inconsistent germination of sclerotia produced in soil was attributed to the presence of contaminating microorganisms on the sclerotial surface.