[The practical application of plant bioregulators (author's transl)].
In this contribution the following aspects of the practical application of plant bioregulators have been discussed.--What are plant bioregulators from the practical point of view?--What influences are bioregulators supposed to exert on plant growth?--To what uses have bioregulators been put up to now in crop production? From the practical point of view, both endogenous and exogenous substances can be regarded as bioregulators if, in low concentrations and without having any biocidal or nutritive action, they exert an influence on the growth, development and composition of the plant. The bioregulators have been categorized according to their interactions with the five phytohormone groups and a survey is given of those known hitherto, supplemented by a list of further substances with different types of mechanism of action. For the practical use of plant bioregulators a concept of application is described which distinguished between a variant dealing with the botanical and physiological aspects and another with crop cultivation and economic aspects. The practical application of plant bioregulators as it stands at present is indicated by way of various examples. Solutions of decisive problems in the cultivation of crops have been achieved up to now, for example, by strengthening the stems of cereals with gibberellin antagonists and by inducing blossoming, ripening and abscission processes with ethylene generators.