Plant growth regulators and hormones are important in the development of plants because they provide optimal results. Think of them as human hormones where a little concentration can go a long way in changing the growth of plants.
One of the major types of plant hormones are auxins. Here we learn about their function and influence on plant growth.
What Is A Plant Auxin?
An auxin is a chemical substance which helps develop the growth of stems and roots of plants. It can either be naturally produced or chemically synthesized. When generated synthetically, they can be applied as pesticides in high concentrations.
Auxins are generated in the stem, root tips, and buds of plants. This powerful plant growth hormone works mainly to elongate the plant’s cells. However, they give different results on the roots and shoots of plants. A higher concentration of auxins in the root can inhibit the growth of shoots while a higher concentration of the same hormone in the shoots can increase the growth of cells.
The dynamic pattern of auxin dissemination in a plant is an important factor for plant growth, it’s orientation and formation of flowers or leaves. It’s accomplished through a very complicated active movement of auxin molecules from one cell to another. Hence, a plant can respond to the environment and adjust to them accordingly without the need for a nervous system.
How Does It Affect Plant Growth?
The main function of plant auxins is to promote cell division, as well as increase the growth of stems and roots. These plant growth hormones are involved in different development changes including phototropism, hydrotropism, and geotropism.
Here are the key effects of auxins on plant growth:
● Stimulates Cell Elongation
Auxins are known to advance cell elongation. However, this effect doesn’t manifest in intact plants. Perhaps it’s because there is already a sufficient number of auxins present in intact plants so there’s no need for extra auxin nourishment.
When auxins boost cell elongation, they increase the wall plasticity and improve the water uptake. They also synthesize the enzymes that are needed for cell wall synthesis. As a result, they increase the plant length.
● Maintains Apical Dominance
Apical dominance is another effect of plant auxins synthesizing in the apical meristem. This phenomenon happens when the apical bud outgrows the lateral buds and inhibits the growth of the latter. When the auxin moves downwards, correlative inhibitors are also formed which inhibit the development of lateral buds.
Once the apical bud is eliminated, the succeeding axial bud grows quickly. This makes the plant appear bushier. When you see a gardener trimming a hedge, he or she is applying apical dominance.
● Controls Seedling Orientation
Have you observed that seedlings usually bend to where the light is? However, the orientation of plants depends on the location of the auxins and how they affect the cells within the plant. Because of gravity, auxins move downwards and sideways, away from light. This makes the plant stem tip curve toward the light, a motion also known as phototropism.
For instance, a plant shoot grows towards the light. In this case, the shaded side of the plant has a higher auxin concentration. More cells are developed on the shaded side, hence it grows longer and makes the plant grow toward the light.
Plant shoots usually grow upwards when the auxin is found in its shoots. Meanwhile, the plant tends to grow downwards when the auxins are found in the roots.
● Promotes Cell Division
Auxins can initiate and promote cell division in the cambium and tissue culture. Cell division in the cambium helps in the healthy growth of the stem. Cell division in tissue culture, on the other hand, is important in the development of callus, an undeveloped mass of cells.
● Stimulates the Growth of Roots
At very low concentrations, auxins can help stimulate the growth of roots. Never use a higher concentration because they’ll do the opposite and limit root growth. When an auxin is placed onto a cut stem, the stem will start to grow roots at the cut.
● Stimulates Seedless Fruit Development
Auxin is popular in promoting parthenocarpy, or the development of seedless fruits without fertilization, in many plants. Applying auxins to the flower allows tomatoes, apples, and cucumbers to develop seedless fruits.
● Stimulates Uniform Flowering
In general, auxins restrict flowering in plants but pineapples are a different case. Spraying auxins promotes uniform flowering in the entire pineapple crop. These plant growth hormones also help in delaying the formation of flowers in lettuce.
The Most Common Plant Auxins and How to Use Them
1. Indole Acetic Acid
The most popular naturally occurring auxin is indole acetic acid (IAA). This is generated by algae, bacteria, fungi, and plants. It enlarges the xylem cells and thickens the plant’s cambium layer.
IAA is the most effective native auxin and produces most of the auxin effects in intact plants. The stability of this native auxin can be controlled in several ways in plants including synthesis, conjugation, and disintegration of its molecules. Its colorless composition means it is easily dissolved in aqueous solution.
In plants, IAA works in the development of shoots and roots. It shifts location by transport proteins and a designated importer. As it moves from one cell to another, IAA reduces the pH and the cell wall allowing the penetration of water into the cell. This makes it possible for plants to bend and extend their length towards the light.
IAA is mainly utilized in horticulture to stimulate root growth. It’s also used in greenhouses, on farms, and even in gardens to increase plant growth and agricultural output. No reports have been made about the toxicity of the compound to the crops.
Here’s how to prepare the solution:
● Dilute IAA in ethanol and add water to increase the capacity.
● If essential, mix the solution so the plant growth regulator dissolves properly.
● Using a 0.2-micron filter, filter or autoclave the solution to remove any microorganisms.
● Store the sterilized solution at -20 degrees Celsius.
The concentration of IAA may be different depending on the medium utilized. The concentration may usually range between 0.01 mg/ml and 3.0 mg/ml.
Power Grown’s Indole Acetic Acid is sold in soluble powder form. To prepare, simply mix it with water. Check the instructions to see how many scoops are needed.
There are many creative ways to apply IAA on plants more efficiently. Here are the most common methods of IAA application on plants.
● Spray
The spray method often uses a backpack or a portable sprayer. A boom sprayer is ideal if you want to cover a large area. When using this method, ensure to cover the area evenly. About 2 quarts of spray solution is enough to cover 100 square feet.
● Drenching
This method usually provides more consistent effects and tends to last longer than the spray application. However, you need to utilize a larger quantity of the diluted solution. With this method, the top of the plant’s growing media is usually drenched.
● Sprench
The sprench method is a hybrid of the spray and drench methods. It gives a more drenching effect compared to the spray method but uses a higher amount of spray. The amount is double the volume of the spray application while the concentration is normally less.
● Bulb Soaking
Also known as bulb dipping, this method is specifically used for bulb crops. It’s easy to do. Simply dip the bulb in the solution, then plant. The chemical content and the soaking duration may vary depending on the plant species.
● Pre-Pan Dip of Cuttings
As you already know, IAA is known to quicken the root initiation in plants for better propagation. Thus, you can use IAA to help set off rooting in stem cuttings. Simply apply 10 mg/L of IAA below the cutting.
2. Indole Butyric Acid
Another agriculturally important auxin is indole butyric acid (IBA). This synthetic auxin is used in different products to improve propagation rates. When applied to cuts, they can instigate the accidental formation of roots.
IBA is used on a lot of crops and ornamentals to increase growth and develop fruits, flowers, and roots. Many people consider this substance more effective than the natural form because plants break it down fast. This is safe for humans and the environment.
This plant auxin can be used in nursery plants, food crops, and ornamental turf to name a few. It can be used as a growth enhancer to improve the quality and yield of plants.
IBA from Power Grown is 99% pure so dilution is essential to accomplish a consistency that’s perfect for your intended use. Once blended, don’t refrigerate or store the solution, and use right away. Always make sure to read the included instructions.
To use, simply apply it to the soil or spray directly onto the plants. You can also use it as a dip for cuttings.
3. Naphthaleneacetic Acid
Naphthaleneacetic acid (NAA) is a synthetic plant hormone used in a lot of commercial plant rooting horticultural products. This product can be utilized in many instances, from promoting the growth of vegetables and fruits to propagating stems and leaf cutting.
In the US, products that contain NAA need to be registered by the Environmental Protection Agency (EPA) as pesticides. It seems to be toxic to plants and animals when used in high concentrations.
NAA is known to increase cellulose fiber development in plants when used together with gibberellic acid. It can also help reduce the rate of thinning and premature dropping of fruits from the shoot. You can also use it on a variety of crops, such as potatoes, apples, and oranges.
This versatile hormone also helps reduce the number of seeds in fruit and even to generate seedless fruit in some instances. It’s also potent in increasing the growth of corn, wheat, and other cereal crops, as well as being proven to increase grain weights and tillering.
The NAA of Power Grown is soluble in water. Before use, dilute it well. Never store or refrigerate the solution. Complete instructions are included separately.
For best results, apply it after blossom fertilization. The concentration should only be between 20 to 100 microgram per mL. Apply the solution by spraying directly onto the plants.
Contact Power Grown Today!
Power Grown offers the most effective plant regulators and hormones. We also have fertilizers and other products to nourish the health of your plants. All products are naturally sourced. If you would like to buy IAA, IBA, naphthaleneacetic acid, and/or any other related products, please call 916-474-0451 or visit our site at https://www.powergrown.com.
Related Links:
https://www.powergrown.com/information/auxins/
