Symptome von Bormangel und Borüberschuß bei Hibiscus esculentus

Abstract

Boron deficiency and Boron toxicity in Hibiscus esculentusThe development of symptoms in Okra under conditions of B‐deficiency and B‐toxicity was observed. It was compared if the symptoms correspond with the B‐contents and the growth of the plants.Symptoms of Boron deficiency in Okra are the same as in the other annual dicotyledons. The first visible microscopical symptom is a disturbance in the cambium region. Characteristic is an enlargement of the cambium. New divided cells do not differentiate. Visual symptoms are breaking of stems and petioles, thickening of these organs, cracking, dying of the tips and falling of buds. With a periodic supply of Boron correlations between Boron content and deficiency symptoms were not found.In the B‐toxicity range small yellow chlorosis developed on the margins of the older leaves. These symptoms are not to be used for diagnosis. Boron contents higher than 72 μg B/g DM gave a better measure for B‐toxicity. Growth and development of symptoms were in agreement with the high Boron contents.