Submitted to: Agronomy Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 11/1/2003
Publication Date: 11/1/2003
Citation: Day, K., Clapp, C.E., Vial, R.S., Chen, Y., Palazzo, A.J., Bugbee, B., Tew, J. 2003. Plant growth stimulation by fulvic acids. Agronomy Abstracts. Abstract Paper No. S03-vial728219-Poster. Interpretive Summary:
Technical Abstract: Fulvic acids (FA) under conditions of adequate mineral nutrition consistently show stimulation of plant growth when added to hydroponic nutrient solutions. Similar plant growth enhancements have been observed when FAs are applied to the foliage of plants grown in complete nutrient solutions. The degree of stimulation varies depending on the concentration of FA in the nutrient solution and on the source of FAs. A unique system was developed and tested for comparing the biological effects of various commercial and naturally-occurring FAs at similar concentrations either when added to the nutrient solutions or foliar-sprayed onto the plants. All of the FAs caused increased root and shoot growth on corn and soybeans when applied to the foliage. Some of the commercial FAs, however, which contained phosphoric acid, had negative interactions when added to the nutrient solutions. Some of the commercial FAs also decreased root and shoot growth relative to the control because of this interaction. It was found that their impact on the nutrient solution decreased pH below ideal levels. Attempts to correct the pH with lime and sodium hydroxide caused much of the iron in the nutrient solutions to precipitate and iron deficiency symptoms were observed. Foliar applications of FA were a better means for comparing the efficacy of various FA sources.