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Plant Physiology 89:879-882 (1989) © 1989 American Society of Plant Biologists Seed Dormancy in Red Rice 1VII. Structure-Activity Studies of Germination StimulantsDepartment of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Louisiana State University, Baton Rouge, Louisiana 70803, Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
Many chemically dissimilar substances break dormancy of seeds, but the relationship between chemical structure and physiological activity is unknown. In this study, the concentrations of organic acids, esters, aldehydes, alcohols, and inorganic weak acids required to elicit 50% germination of initially dormant, dehulled red rice seeds (Oryza sativa) were determined. The activity of most substances was very highly and inversely correlated to lipophilicity as measured by octanol/water partition coefficients; chemicals with the highest partition coefficients required the lowest concentrations to elicit the germination response. Relative efficacy was also dependent upon the functional group; generally, monocarboxylic acids were more effective than aldehydes, esters, hydroxyacids, and alcohols. Relative hydrophobicity plots supported a modulating role of the functional group. Dormancy-breaking activity of methyl formate, formic acid, nitrite, azide, and cyanide was higher than predicted based on lipophilicity and apparently was related to molecular size; compounds with smaller molecular widths were required at lower concentrations to achieve the 50% germination response.
1 Approved for publication by the Director of the Louisiana Agricultural Experiment Station as manuscript number 88-38-2542. Supported in part by the United States Department of Agriculture, Agricultural Research Service, Competitive Grants Program, Agreement No. 86-CRCR-1-1962. This article has been cited by other articles:
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