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Physiology and Biochemistry

Carbohydrate Exudation from Pea Seeds: Effect of Cultivar, Seed Age, Seed Color, and Temperature. G. E. Short, Former Graduate Research Assistant, Michigan State University, E. Lansing 48824, Present address of senior author: Dept. of Plant Pathology, 108 Waters, University of Missouri, Columbia 65201; M. L. Lacy, Associate Professor of Botany and Plant Pathology, Michigan State University, E. Lansing 48824. Phytopathology 66:182-187. Accepted for publication 20 August 1975. DOI: 10.1094/Phyto-66-182.

Exudates from pea (Pisum sativum) cultivars Miragreen and Alaska were aseptically collected from sterile seeds and analyzed by the anthrone method for total carbohydrate. The preponderance of carbohydrate was exuded during the first 18 hours of incubation at 22 or 30 C, but at 10 C significant carbohydrate exudation persisted for about 48 hours. Total carbohydrate exuded during the first 48 hours of seed germination ranged from 185 to 7,119 µg glucose equivalents per seed depending on cultivar, seed age, seed color, rate of imbibition of water, and incubation temperature. Total carbohydrate exuded by Alaska seeds was not affected by temperature. Eight-year-old Miragreen seeds imbibed water faster and exuded several times more carbohydrate during the first 48 hours of germination than did Miragreen seeds which were less than one year old, and yellow Miragreen seeds exuded significantly more carbohydrate than did green Miragreen seeds of a similar age. Conditions which favored high amounts of nutrient exudation generally corresponded with conditions which have favored high levels of pathogen spore germination around seeds and high amounts of seedling decay, suggesting a direct causal relationship between amounts of carbohydrate released from seeds and disease incidence.