Effect of CO2enrichment and nitrate application on vegetative growth and dinitrogen fixation of wild and cultivated soybean varieties

Abstract

A wild soybean variety (Glycine soja Sieb. and Zucc. line Nakei-No. 1) and a cultivated soybean variety (Glycine max L. Merr. cv. Tamahomare) were subjected to CO2 enrichment and/or NO3-N application (50 and 300 ppm), and the growth and dinitrogen fixation in the vegetative growth stage were examined. 1. The whole plant weight of the cultivated soybean variety was more promoted by CO2 enrichment than by NO3-N application, while that of the wild one was enhanced by NO3-N application compared with CO2 enrichment. 2. The dinitrogen-fixing activity which was lower in wild soybean variety than in the cultivated one increased by CO2 enrichment in both soybean varieties, when nitrate was not applied to the plants. The increase by CO2 enrichment was remarkable in the cultivated soybean variety and was negligible in the wild one. In both soybean varieties, the dinitrogen-fixing activity decreased by the application of 50 ppm NO3-N and recovered approximately to the same level as that in the plants which did not re...