Tuinbouwkundige toepassingen van gibberellazuur

The initiation of new flower buds in Pelargonium zonale Ait. was strongly inhibited by GA 3 . The duration of development of the initiated umbel was diminished and the stalk of the umbel elongated. The winter dormancy of the flower buds of Convallaria majalis started earlier with a dry or warm cultivation and by GA 3 during the growth or during storage. GA 3 was not able to break winter dormancy of the buds without previous cold treatment.
After castration and GA 3 treatment of some varieties of pears many treated flowers set fruit parthenocarpically. After night frosts in 1960 and 1962 a considerable fruit set was obtained from severely frosted flowers after GA 3 treatment of pears. Thus night frost damage to pears could be controlled with GA 3 .

The induction of parthenocarpy in apples with GA 3 did not succeed, neither after castration or after night frost. A possible improvement is the use of other gibberellins, especially GA 4 . The presence of seeds in the fruit proved necessary until the June drop. Undesired effects of GA 3 may be a decrease in the number of flower buds or abnormal fruit shape.

The growth of the heads of unchilled roots of Belgian chicory was strongly stimulated by GA 3 . GA 3 treatment increased the number of male flowers in cucumber, favoured the bolting of spinach, hastened the ripening of tomato fruits, but did not favour the growth of the fruits of Solanum melongena and Capsicum annuum.