Adapted from a dissertation by the senior author submitted to the Academic Faculty of Colorado State University in partial fulfillment of the requirements for the Ph.D. degree.
Article first published online: 2 MAY 2006
Volume 97, Issue 2, pages 269–276, June 1984
How to Cite
AMES, R. N., PORTER, L. K., ST. JOHN, T. V. and REID, C. P. P. (1984), NITROGEN SOURCES AND ‘A’ VALUES FOR VESICULAR–ARBUSCULAR AND NON-MYCORRHIZAL SORGHUM GROWN AT THREE RATES OF 15N-AMMONIUM SULPHATE. New Phytologist, 97: 269–276. doi: 10.1111/j.1469-8137.1984.tb04131.x
Present address of senior author: USDA-ARS, Western Regional Research Center, 800 Buchanan St, Albany, California, USA 94710.
- Issue published online: 2 MAY 2006
- Article first published online: 2 MAY 2006
- (Accepted 13 January 1984)
- vesicular-arbuscular mycorrhiza;
- nitrogen sources;
- ‘A’ values;
- 15N-ammonium sulphate
Mycorrhizal and non-mycorrhizal sorghum [Sorghum bicolor (L.) Moench] plants were grown in soil treated with one of three rates of (15NH4)2SO4, fertilizer. Mycorrhizal plants did not significantly differ from non-mycorrhizal plants in total plant dry weight, total plant N, or percent utilization of the applied N by the whole plant at any fertilizer rate. However, the atom percent 15N excess in shoots, roots and the whole plant, and percent N derived from fertilizer were significantly higher for non-mycorrhizal plants at the intermediate level of fertilizer N. The percent N derived from native soil sources, and ‘A’ values were significantly higher for mycorrhizal plants, compared to non-mycorrhizal plants, at the intermediate but not low or high fertilizer rates. The results suggest that, at the intermediate fertilizer rate, where plants produced the most growth, mycorrhizal sorghum plants derived N from a source that was less available to non-mycorrhizal plants.