pH Dependence of the Copper Effect on Flowering, Growth and Chlorophyll Content in Lemna paucicostata 6746

The short-day plant Lemna paucicostata 6746 took up the sameamount of copper from the medium whether the pH of the mediumwas 4.1 or 5.1. At pH 4.1, an addition of copper to the mediumresulted in an unchanged chlorophyll content, a somewhat reducedgrowth rate and a substantial induction of long-day flowering.By contrast, at pH 5.1 the same copper concentration causeda reduction in the chlorophyll content and strong inhibitionof growth, but it did not induce any long-day flowering. (Received June 14, 1982; Accepted October 14, 1982)