Sexual differentiation in cucumber: Abscisic acid and gibberellic acid contents of various sex genotypes

The AbA content of cucumber shoot tips was determined by GLC.Shoot tips of monoecious plants had a higher AbA content thanthose of gynoecious ones, and SD conditions caused higher AbAcontent than LD conditions. AbA content per unit dry weightof young floral buds was 5- to 9-fold higher than in older ones. A GLC method was developed to allow parallel identificationand quantitative determinations of GA₃ and AbA with the samesample. The shoot tip contents of both growth substances weredetermined at four developmental stages of the monoecious plant.Both significantly increased until the 12th day after plantingthen decreased; the GA₃ content decreased markedly. A general hypothesis for the role of growth substances in regulatingsex expression of cucumber is presented and discussed. (Received January 7, 1977; )