Plant hormones (phytohormones) are physiological intercellular messengers that are needed to control the complete plant lifecycle, including germination, rooting, growth, flowering, fruit ripening, foliage and death. In addition, plant hormones are secreted in response to environmental factors such as abundance of nutrients, drought conditions, light, temperature, chemical or physical stress. Hence, levels of hormones will change over the lifespan of a plant and are dependent upon season and environment.
The term “plant growth factor” is usually employed for plant hormones or substances of similar effect that are administered to plants. Growth factors are widely used in industrialized agriculture to improve productivity. The application of growth factors allows synchronization of plant development to occur. For instance, ripening tomatoes can be controlled by setting desired atmospheric ethylene levels. Using this method, fruits that are separated from their parent plant will still respond to growth factors; allowing commercial plants to be ripened in storage during and after transportation. This way the process of harvesting can be run much more efficiently. Other applications include rooting of seedlings or the suppression of rooting with the simultaneous promotion of cell division as required by plant cell cultures. Just like with animal hormones, plant growth factors come in a wide variety, producing different and often antagonistic effects. In short, the right combination of hormones is vital to achieve the desired behavioral characteristics of cells and the productive development of plants as a whole.
Traditionally five major classes of plant hormones are listed: auxins, cytokinins, gibberellins, abscisic acid and ethylene. However as research progresses, more active molecules are being found and new families of regulators are emerging; one example being polyamines such as
putrescine or spermidine.
Auxins
Auxin is the active ingredient in most rooting mixtures. These products help the vegetative propagation of plants. On a cellular level auxins influence cell elongation, cell division and the formation of adventitious roots. Some auxins are active at extremely low concentrations. Typical auxin concentration range from 0.01 to 10 mg/L.
Selection of Biosynth's Products:
B-2700: 4-Biphenylacetic acid
C-4140: 3-Chloro-4-hydroxyphenylacetic acid
H-7100: 4-Hydroxyphenylacetic acid
I-1000: Indole-3-acetic acid ultra-pure
I-1300: Indole-3-acetyl-L-alanine
I-1400: Indole-3-acetyl-DL-aspartic acid
I-1700: Indole-3-acetyl-DL-tryptophan
I-1800: Indole-3-acetyl-L-valine
I-2010: Indole-3-butyric acid ultra pure
I-4000: Indole-3-propionic acid N-1420 alpha-Naphthaleneacetic acid
Cytokinins
Cytokinins promote cell division, stimulate shoot proliferation, activate gene expression and metabolic activity in general. At the same time, cytokinins inhibit root formation. This makes cytokinins useful in culturing plant cell tissue where strong growth without root formation is desirable. Natural cytokinin hormone levels are high during maximum growth periods of mature plants. In addition, cytokinins slow the aging process in plants. Concentrations of cytokinin used for horticulture vary between 0.1 to 10 mg/L
B-1000: 6-Benzyladenine horticultural grade
K-4000: Kinetin
Z-3000: trans-Zeatin Riboside
Gibberellins
Gibberellins are derivatives of gibberellic acid. They are natural plant hormones and promote flowering, stem elongation and break dormancy of seeds. There are about 100 different gibberellins, but gibberellic acid (GA3) is the most commonly used form. Gibberellins are fundamental to plant development especially with respect to the growth of stems. Low levels of gibberellins will prevent plants from reaching their natural height. Gibberellin synthesis inhibitors are extensively used in grain production to keep stems artificially short: shorter and thicker stems provide better support and resist weather conditions better too.
Gibberellins are particularly effective at breaking seed dormancy and at speeding up germination. Seeds that are difficult to germinate are frequently treated with gibberillic acid solutions.
G-2700: Gibberellic acid GA3 90+%