Effect of Humic Acids on Nodulation and Dry Matter Production of Soybean, Peanut, and Clover1
- K. H. Tan and
- D. Tantiwiramanond2
Humic substances have been reported to increase plant growth. A stimulating effect on the growth of legumes may improve biological nitrogen fixation in soils. The present investigation studied dry matter production, nodulation and N content in nodules of soybean (Glycine max L., ‘Bragg’), peanut (Arachis hypogaea L., ‘Florunner’), and clover (Trifolium vesiculosum, ‘Arrow leaf’), grown in sand cultures containing a fertilizer mixture and 0 to 800 mg kg−1 (ppm) of fulvic acid (FA) or humic acid (HA). The results indicated that FA and HA were capable of stimulating dry matter production in the plants. Dry weights of roots and nodules showed a tendency to increase over the control at 100 to 400 mg kg−1 (ppm) of FA or HA. The increases in total dry matter production were statistically significant at 800 mg kg−1 (ppm) of FA or HA, and a positive correlation was noticed between increases in dry weights of shoots, roots, and nodules and FA and HA concentrations. Fewer nodules were produced by plants receiving FA and HA treatments than the control, but the nodule mass was greater with the FA and HA treatments. The N content of nodules was little affected by the treatments, although a tendency can be noticed that 100 mg kg−1 (ppm) of FA had decreased the N content in the nodules of both soybean and peanut plants.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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