Plant Hormones

During the 1930s scientists discovered that plant growth was controlled by hormones. A lot of literature on the subject has evolved since then, and new hormones are frequently reported. Four classes of naturally-occurring plant hormones have been identified:

1. Auxins, which are involved in a variety of plant processes including cell elongation, fruit ripening, abscission, and root initiation.
2. Gibberellins (over 40 different ones identified) control cell elongation, flowering, and dormancy.
3. Cytokinins control cell division.
4. Inhibitors cause reduction of cell elongation and appear to control stomata.

Although many of these hormones are known to control certain plant growth processes, when these same hormones are applied to intact plants, there is usually no response.

Plants produce their own hormones, and their growth and development are seldom limited by lack of hormones.

People have tried applying different hormones to the roots and shoots of seedlings, but no hormone treatment yet has proved beneficial to forest seedlings, either in terms of growth or survival. The best treatment that can be applied to a seedling is to lift it at the proper time, minimize PMS, and plant at the proper time of year. Any hormone, fertilizer, or "magic dip" treatment prior to planting is more likely to harm the seedling than to encourage its survival and growth. There may be situations where soil tests indicate a need for fertilizer.

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Last Modified: 07/05/2007