Einfluß der Kulturmethode auf die Ausscheidung von Phytohormonen durch Erbsenwurzeln

Summary Earlier experiments (Tietz 1971 and 1974) had shown that pea roots contain very different amounts of abscisic acid (ABA) according to their growth in a mixture of vermiculite and pumice stones (20.1  μ g ABA/kg) or in water culture (1.31  μ g ABA/kg). Hence it was interesting to test whether roots are able to excrete hormones into the culture media. 5 days old pea seedlings were grown on a water culture for two weeks. The roots were well aerated and in some cases illuminated with fluorescent lamps. An analysis of the culture media using a biotest revealed ABA and auxin activity. A quantitative determination of ABA using gas liquid chromatography yielded about two times more ABA in illuminated vessels in comparison to dark grown controls. The ABA content of the culture media increased towards the end of the experiment whereas the ABA content of roots decreased. The IAA concentration in roots is also dependent on the culture media. Roots growing in sand contain 11.0  μ g/kg fresh weight, pea roots from a water culture only 4.1  μ g/kg. [2- 14 C]-ABA applied to 5 days old pea shoots is transported to the roots only in very small amounts. An illumination of the roots reduces the concentration of [2- 14 C]-ABA in the culture media as well as in the roots Therefore it is concluded that ABA which accumulated after illumination in the roots and in the culture media is mainly synthesized in the roots