[The influence of gibberellic acid on the flower and cone development in hop (Humulus lupulus L.)].

The treatment of the three hop-varieties 'Saazer', 'Hüller Anfang' and 'Hallertauer' with gibberellic acid caused a decrease of the 1000-cone weight, but an increase in cones of each plant.With 'Hüller Anfang' and 'Hallertauer' there was a decrease in α-acid content, in the 'Saazer' variety it remained equal, only when it was treated by the dosage 10 ppm, times two, an icrease in α-acid content resulted.The organoleptic valuation of the cones showed a decrease in quality especially in respect to cone size, Jupulin content and delicacy of aroma. In the 'Huller Anfang' variety a high percentage of cock hops resulted also.Under the influence of gibberellic acid the development of the hop plant is prolonged, so that the ripening of cones is retarded. Early and middle-early varieties thus become middle-early and late varieties.The female flower is somewhat retarded in development; in the extreme case this leeds to complete suppression of all flower parts and a tendency to reduce the female inflorescence to the original leaf shoot. Moreover, the hybrid variety 'Hüller Anfang' formed monoecious plants. The origin of monoecious plants is discussed.The different reactions to treatment with gibberellic acid of the several varieties are caused by the differing stages of plant development at the time of treatment.