Growth-regulating phytohormone (plant hormone) discovered in Japan in 1926 At that time, a rice disease was being studied, which was known in Japan as "crazy rice seedling". Among other things, the plants grew extremely fast. A substance excreted by a fungus (Gibberella fujikuroi) parasitizing on the plants could be identified as the cause or messenger that triggers this process. In 1956, it was then possible to isolate a gibberellin from plants; today, over 110 different species are known. Such hormones are also naturally present in the roots, leaves and berry seeds of vines. They control line growth, seed formation and germination. Gibberellins have been used in the production of table grapes since the 1970s. These are sprayed with gibberellin during flowering and shortly afterwards to produce fewer but larger berries.
Seedless varieties, such as the Sultana, are particularly responsive to this process. This has also been common in fruit growing for some time. For some years now, intensive attempts have been made to use gibberellins in viticulture. The aim is to obtain grapes with loose berries. This could be an alternative to manual thinning out, which is very laborious and labour-intensive. In addition, loose berries greatly reduce the risk of botrytis and other fungal diseases. This would be particularly advantageous for narrow-berry red wine varieties such as St. Laurent or Pinot Noir. A disadvantage of the significantly larger berries is a less favourable ratio of juice to berry skin. In the graph the effect is shown withinternodes of different length and flower sizes depending on the amount of gibberellin. Plant hormones such as gibberellin belong to the large group of plant strengthening agents in the context of gentle plant protection or biological (organic) viticulture.