Abscission: characterization of light control.

Exposure of mung bean (Vigna radiata [L.] Wilczek cv Jumbo) cuttings to low level red light inhibits dark-induced leaf abscission. A 12-hour daily light requirement for maximum inhibition of abscission was equally effective as a continuous red light treatment or shorter light-dark cycles. Transfer of cuttings from dark to light stopped the abscission process at the time of transfer. The available evidence suggests a light receptor located in the leaves with an abscission inhibitor translocated from lighted leaf to the abscission zone.