Das Aneignungsvermögen von Weißer Lupine und Sommerweizen für Nichtaustauschbares Kalium

Abstract

Listen

Translate article

Summer wheat and white lupin were grown in small Mitscherlich pots under greenhouse conditions. Both plants were cultivated in a treatment with (K1) and without (K0) K fertilization The soil contained 230 g clay kg−1 soil and was low in Ca-exchangeable K (47 mg K kg−1 soil). The response in grain yield, as a precentage of the K0 treatment was 107% in wheat and 108% in lupin. The relative K uptake from nonexchangeable K was between 60 and 68% of the total K uptake in white lupin and summer wheat, respectively. This indicates that both plants have a good exploitation potential for clay-fixed K, even though wheat roots were three times longer than those of white lupin. The exploitation potential of wheat for clay-fixed K is explained by a high root density and by a low K uptake m−l root length day−1, which enhances the release of nonexchangeable K. However, in contrast to phosphorus, K had noeffect on the number of proteoid root clusters of white lupin roots grown in soil. It is assumed, that the exploitation potential of white lupin for clay-fixed K is based on an excretion of citric acid by roots of white lupin. Addition of citric acid in a quantity analyzed in the rhizosphere of the proteoid roots of white lupin, increased the amount of electro-ultrafiltration (EUF) extractable clay-fixed K of the soil.