Emanation, Partitioning and Endogenous Levels of Ethylene in Phaseolus Vulgaris Developing Cotyledons

Experiments were carried out to determine qualitative changes in the rate of emanation and endogenous levels of ethylene in the cotyledons of Phaseolus vulgaris at various stages of development and using partition coefficients to test whether qualitative changes in the binding of ¹⁴C₂H₄ occur. Three phases in the rates of emanation of ethylene use were observed, namely, 0-14, 14-24, and 24-48 days after flowering, respectively. The highest endogenous level of ethylene recorded was 728.7 µl kg^-1 during the first 7 days after flowering and progressively declined until maturity. A similar trend was observed for the partition coefficient values but with high values during the 14 days after flowering. Results are indicative of a "storage system" for ethylene in P. Vulgaris developing seeds possibly to remove excess phytohormone from the system or to provide a reserve pool for ethylene in the cell so that levels of free hormone are maintained.