Should I Be Considering the Use of Plant Growth Hormones?

Farmers are always on the lookout for new ways to increase the yields of their corn and soybean crops. Applying products containing plant growth hormones to increase yields in grain crops is likely something new to many farmers, but plant growth hormones have been used in commercial fruit and vegetable production for many years.

Corn and soybean plants produce a variety of plant growth hormones. Some of these plant growth hormones, including auxins, cytokinins and gibberellins, function to promote growth, whereas other plant growth hormones, such as ethylene and abscisic acid, function to inhibit growth. Plant growth hormones commonly interact with each other to help the plant grow and adjust to the ever-changing environmental conditions throughout the growing season.¹

Since increasing crop yields is the primary goal, companies that participate in this market segment focus their research on developing products that contain plant growth hormones that promote growth. However, since fruit and vegetable crops typically produce considerably more revenue per unit of land area, most research dollars are spent developing new products for those crops rather than for grain crops.¹

During the summers of 2015 and 2017, Iowa State University conducted trials in corn and soybeans to test the performance of various commercially available products containing plant growth hormones. The results for both years did not show an advantage for using any of the plant growth hormone products tested.^2,3 It is also important to note that plant growth hormone products are applied because of their potential benefit to the crop, but they can also cause detrimental effects by upsetting the normal balance of hormones in the plants.⁴

For a plant growth hormone product to consistently increase grain crop yield, the product must show a positive response across several varieties or hybrids of the crop, be stable enough for the plant to have time to uptake it, be in a form the plant can readily uptake and utilize, be active over a relatively long period of time, and have the ability to override environmental effects.¹

Should you be considering the use of plant growth hormones? The relatively recent Iowa State University on-farm test results do not support their use, but the only way for you to know for sure is to conduct your own on-farm testing with them.

Paul Parcher

Agronomist

¹Harms, C.L. and Oplinger, E.S. 1988. Plant growth regulators: Their use in crop production. North Central Region Extension Publication 303. https://www.semanticscholar.org/.

²Fawcett, J., Koopman, Z., and Miller, L. 2016. On-Farm Corn and Soybean Plant Growth Regulator Trials. RFR-A1559. Farm Progress Reports: Vol. 2015: Issue 1, Article 13. https://lib.dr.iastate.edu/.

³Fawcett, J., Rogers, J., Beedle, C., and Rossiter, L. 2018. On-Farm Plant Growth Regulator Demonstration Trials in Corn and Soybean. Farm Progress Reports: Vol. 2017: Issue 1, Article 15. https://lib.dr.iastate.edu/.

⁴Abendroth, L. and Elmore, R. 2005. For corn and soybean: Foliar applications of plant growth hormones. Crop Watch. No. 2005-11. University of Nebraska – Lincoln. https://digitalcommons.unl.edu/.

Web sites verified 8/10/2020.

Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

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