Hormones and Growth
Anybody who was ever a teenager knows about hormones. We produce them naturally and in differing amounts throughout life, but it is the adolescent years that get most of the attention. Yes, we all know about mood swings and body development because these hormone-influenced conditions hit close to home. Plants produce hormones, too, and their role in plant growth and especially propagation cannot be underestimated. Naturally occurring plant hormones include auxins, cytokinins, gibberellins, ethylene and abscisic acid. The latter is important in fruit ripening, as when we put a cut apple into a plastic bag with green bananas to speed them to the table. Gibberellins are noted for their impact on cell division and elongation. You may know someone who ‘gibbs’ their camellias, applying gibberellic acid, a gibberellin, to increase bloom size. Cytokinins influence cell division, lateral bud development, and leaf longevity. Auxins are the hormones used to promote rooting, but they are also promote uniform flowering and fruit set and, in some cases, forestall early fruit drop.
The auxin known as IBA (indole-3-butyric acid) contributes to the formation and growth of healthy roots and is the substance in Hormex Rooting Powders of various strengths. Vitamin B-1 (thiamine) is the additional active ingredient in Hormex Liquid Concentrate. B-1 is thiamine, a vitamin rather than a plant hormone or auxin. By combining vitamin B-1 with liquid auxin, Hormex Liquid Concentrate promotes thrifty growth at all stages in a plant’s development.
How fast and how well cuttings take root and begin to grow depends on the condition of the plant material, the media you choose to root in, and the temperature of the media, air, and water used in the process. Rooting also depends on the plant’s capacity to form roots, its hormonal signals and suitable growing conditions; IBA quantity alone does not determine success. The role of IBA in plant growth is to regulate and direct growth by working in relation to other hormones like cytokinins. For example, the ratio of auxin to cytokinin in some plants can determine whether cells differentiate into roots or shoots. By adding Hormex products to the process, we increase the auxin influence towards roots.
How this influence occurs can be attributed to the nifty ability of auxin molecules to move from cell to cell, to marshal their influence where it is needed. It’s a talent we mere mortals do not share which imparts to the plants the ability to shift growth patterns right down at the cellular level. It even allows them to react to some external threats. Callus formation and root initiation are different processes, and roots can form independently of callus. Allowing the cut surface to dry before planting can be useful for many succulent cuttings, but it is not a universal practice for all cuttings or a guarantee of faster rooting.
All auxins are hormones, but not all hormones are auxins. Chemically, each auxin consists of an aromatic ring and carboxylic acid group in quite elegant molecular arrangements of carbon and hydrogen. When I was a teenager, we didn’t talk much about hormones, human or plant, but a good biology teacher offered extra credit for a report on plant anatomy and I stumbled into a curiosity about how growth happens. In college, I learned about plant hormones in class but really first observed their power when I tried to root bougainvillea and lollipop plant, aka golden shrimp plant. Both are rather woody, tropical plants then in consideration for greenhouse production schedules. My first task was to determine whether tip cuttings or stem cuttings would root better and to compare cuttings rooted using IBA with those that had no hormone applied. I used a single blade knife to make clean cuts from healthy stems on the stock plants. I made labels, filled flats with a damp perlite/peat media, and tapped out a little rooting hormone onto a brown paper towel laid on the bench in the head house. I stuck the untreated groups and then rolled each remaining stem base in rooting powder and shook off the excess before sticking it. Virtually every tip cutting died before roots could form, but the 2 that survived were from the treated group. The stem cuttings were much more successful overall. Some of the untreated made a few roots, but nearly all the treated stem cuttings rooted and rooted very well in the same length of time. The proof of the pudding, as they say, was in the hormone.
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