Free amino acids in the seed and root exudates in relation to the nitrogen requirements of rhizosphere soil Fusaria

Summary The amounts of amino acids in seed exudates were generally higher than in root exudates of the same plant. The spectra and relative abundance of amino acids in both plants were similar but they were generally more abundant in cowpea exudates than in sorghum. Glutamic acid and alanine were the most abundant amino acids in the seed and root exudates of both plants. The proportions of the amino acids in the seed exudates were comparable to that stored in the seeds. Many of the major amino acids identified in the exudates were also found to support thein vitro growth ofFusarium spp. isolated from the rhizosphere and rhizoplane. This suggests that the amino acids exuded might contribute signficantly to Fusaria nutrition and its consequent predominance around the root. The significance of this pathogenesis is also discussed.