Effect of pod removal on dinitrogen fixation of soybean plants differing in growth habit

Abstract

Eight cultivated soybean varieties (Glycine max l. Merr.) and one wild soybean variety (Glycine soja Sieb. and Zucc.) differing in their growth habit, i.e. determinate and indeterminate types were grown in the field. The effects of pod removal on the dry matter production, N accumulation and dinitrogen-fixing activity in the nodules were examined. In all the determinate types, pod removal decreased the dry weight and N content in the whole plant and resulted in a decrease of dinitrogen-fixing activity in the nodules. In contrast pod removal had little effect on the dinitrogen-fixing activity of all the indeterminate types, mainly due to increase in the N content of the stems plus petioles in the Lee and Harosoy plants and to the increase in the dry weight of the stems plus petioles in other indeterminate types. The relative ureide content ((ureide-N/total-N)× 100) of all the plant parts in the determinate types increased by pod removal, whereas that of plant parts except nodules in the indeterminate types...