Factors Affecting Dormancy in Tubers of Cyperus esculentu

Abstract

1. Twelve per cent of the tubers of Cyperus esculentus germinated when harvested in the fall, whereas 95% germinated when harvested the following spring. 2. Storing tubers at 3⚬ C. promotes germination of tubers and numbers of shoots per tuber. Washing freshly harvested tubers in cold water also promotes their germination. 3. Cutting tubers in half transversely favors sprouting of buds in the apical half. No sprouts appeared from buds in the basal half of tubers, whether severed or not. 4. The application of a 5% tuber extract to washed tubers reduced both the number of tubers that germinated and the number of shoots per tuber. Tuber extracts (5% or less) also inhibited germination in six of eight crop seeds tested. Concentrations of the extract that allowed germination of alfalfa seeds reduced root growth. 5. Gibberellic acid initially stimulated germination of tubers and increased the number of shoots per tuber, but after 5 weeks, fewer shoots per tuber had been produced than in the control. Dry weight per shoot increased with increased concentrations of gibberellic acid, however. 6. The tuber extract was heat stable, non-volatile, water-soluble, dialyzable, not adsorbed on charcoal, not eluted from an alumina column by solvents higher than methanol in the eluotropic series, and was not adsorbed on either cationic- or anionic-exchange resins. 7. From chromatography studies in which sections were eluted and bioassayed with alfalfa seeds, an Rf between 0.8 and 1 was obtained using butanol: ethanol:water as the solvent system and an Rf between 0.9 and 1 using butanol:acetic acid:water as the solvent system.