Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The effect of 6‐benzylaminopurine (BAP) was studied by measuring the amylase activity of leaf extracts and the starch content of chloroplasts in <jats:italic>Stellaria media</jats:italic>‐plants cultivated for five days in solutions containing different quantities of BAP.</jats:p><jats:p>Small amounts of BAP decreased amylase activity in weak‐growing plants. In strong‐growing ones the effect was variable. However, in all experiments very high amount of this growth regulator caused a great increase in amylase activity which was accompanied by a relatively high concentration of starch in the chloroplasts. The induction of amylase activity was thus not high enough to diminish the starch content. This is supposed to be due to the lack of a sink organ since the growth of roots and shoots was greatly inhibited in concentrated BAP‐solutions (10<jats:sup>‐5</jats:sup><jats:italic>M</jats:italic> or more). In these cases the plants usually died during the first week.</jats:p><jats:p>In some cases small amounts of BAP increased the growth of S. media, and high concentrations inhibited it causing characteristic morphological changes, such as creeping growth pattern, small, thick leaves and the turning up of the leaf margins.</jats:p><jats:p>Benzylaminopurine also caused increased resistance to aging, especially in low concentrations (10<jats:sup>–7</jats:sup>–10<jats:sup>–6</jats:sup><jats:italic>M</jats:italic>).</jats:p>