What proportion of plant hormones should we add for chili pepper plants?

Q:

What proportion of plant hormones should we add for chili pepper plants?

A:

The type of concentration of plant hormones (plant growth regulators) to use on chili pepper plants depends on what process you are trying to control. Plant hormones are not routinely used for the general production of greenhouse and hydroponic chili plants under normal growing conditions as the plant produces sufficient of these for optimal growth, and there is a risk that incorrect application can actually have a negative effect and may even kill or severely harm plants. The main use of plant hormones on chili plants is under adverse growing conditions, such as high or low temperatures where application helps reduce flower drop thus increasing fruit set and yields. Under adverse growing conditions chili crops can have a significant reduction in growth and yields when high daytime temperatures (more than 86°F) coupled with warm nights cause abscission of flowers and poor fruit set which severely restricts yields. The application of foliar sprays of the NAA (Naphthaleneacetic acid) auxin can enhance fruit set and yields under these conditions and make the crop more profitable. One study has also found that use of NAA at foliar applied rates of 20-40ppm not only improved fruit set, but also increased plant height and the number of primary branches in chili plants, however other studies show varying responses to applied plant growth regulators, so some experimentation may be required. Other plant growth regulators which may have an effect on chili pepper plants have been reported as being GA3 (Gibberellic acid) at 10ppm, and triacontanol at 5ppm, which both had a similar effect to NAA by promoting greater fruit set and resulting yields under adverse environmental conditions.

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Written by Lynette Morgan
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Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University, New Zealand. Lynette is a partner with Suntec International Hydroponic Consultants and has authored several hydroponic technical books. Visit suntec.co.nz for more information.  Full Bio

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