No abstract

The polyether antibiotic maduramicin and its methyl ester derivative inhibited photophos phorylation and proton uptake in isolated spinach chloroplasts. Both compounds also en hanced basal and phosphorylating electron transport and stimulated Mg2+-dependent A T Pase activity, therefore, they behave as uncouplers of photophosphorylation being the methyl ester derivative more potent than the parent compound. On the other hand, maduramicin inhibited germination and radicle elongation of several crop and weed species. In addition, the antibiotic caused phytotoxic injury and fresh weight reduction to 4-to-6 week old seed lings of two weed and two crop species when applied at 1 0~4 m by foliar application in the greenhouse.