Tropical Grasslands (2006) Volume 40, 237–243

Enhancement of ethylene production by dormant seeds of Stylosanthes humilis induced to germinate in closed environments

RAIMUNDO SANTOS BARROS AND DIMAS MENDES RIBEIRO

Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil

Abstract

Scarified dormant seeds of Townsville stylo (Scarified dormant seeds of Townsville stylo (Stylosanthes humilis) induced to germinate in sealed Erlenmeyer flasks produced ethylene, which, upon accumulation in their atmospheres, led to enhanced ethylene production and improved germination. Production of ethylene by dormant seeds could be enhanced by increasing seed number in a particular size of flask or by decreasing flask volume with the same seed number. Injection of ethylene at very low concentrations into sealed flasks also enhanced production of the gas by seeds. Stimulated ethylene production and seed germination, however, seemed to be limited by both the low capacity for ethylene biosynthesis and the low sensitivity of dormant seeds to the gaseous regulator by comparison with those of climacteric plant organs. The results suggest a mechanism by which seed dormancy may be broken by germination of other nearby seeds, contributing to flushes of germination under favourable conditions.

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