Plant growth regulators, a gem among agricultural inputs, are gradually gaining wider recognition. They play a significant role in improving quality and yield, increasing survival rates, protecting flowers and fruits, and enhancing crop resistance, achieving twice the result with half the effort. So, what are the specific effects of these amazing regulators? How are they classified? How should they be used? What precautions should be taken? In the following sections, we will provide a detailed explanation to help you better utilize this treasure trove of agricultural inputs.
First, plant growth regulators play a crucial role in regulating plant growth and development. They can influence plant morphology and growth habits by regulating plant height, promoting tillering and branching. For example, growth retardants such as paclobutrazol and chlormequat chloride can inhibit stem elongation, resulting in dwarfed plants. This is particularly useful in flower cultivation, effectively controlling the height of chrysanthemums, preventing excessive growth, and enhancing their lodging resistance. Cytokinins promote the growth of lateral buds, increasing the number of tillers or branches, thereby improving crop yield and quality. Taking wheat as an example, the rational use of cytokinins can promote wheat tillering, increase the number of effective ears, and thus improve overall yield.
A. Regulating Plant Reproduction
(1) Accelerating Rooting: Auxin regulators, such as indolebutyric acid and naphthaleneacetic acid, are widely used as rooting promoters. When propagating roses, grapes, and other plants by cuttings, soaking the cuttings in solutions of these regulators can significantly improve rooting speed and success rate, making the cutting operation more convenient.
(2) Precisely Controlling Flowering and Fruiting: Gibberellins can break plant dormancy and induce flowering. For some plants that require vernalization to flower, gibberellin treatment can achieve flowering without experiencing low temperatures. At the same time, the application of anti-drop agents can effectively prevent flower and fruit drop, improve fruit set rate, and play an important role in the cultivation of tomatoes and other fruits and vegetables.
B. Enhancing Plant Resistance
(1) Improving Drought Resistance: When plants face drought, they naturally produce abscisic acid (ABA), which promotes stomatal closure and reduces water evaporation, thus enhancing drought resistance. Furthermore, some plant growth regulators can optimize root structure, enabling more effective water absorption and retention, further strengthening drought resistance.
(2) Enhancing Cold Resistance: Before the onset of winter, the use of regulators such as brassinolide can adjust plant physiological metabolism, increase intracellular solute concentration, and lower freezing point, thereby mitigating the damage of low temperatures and improving cold resistance.
C. Regulating Fruit Quality and Maturity
(1) Optimizing Fruit Quality: Cytokinins have been proven to effectively improve key quality indicators such as fruit firmness and sugar content. For example, the use of cytokinins in apple cultivation can significantly improve the taste and firmness of apples.
(2) Accelerating Fruit Ripening: Ethephon is an effective fruit ripening agent. For fruits like bananas, harvesting them before they are fully ripe and then treating them with ethephon upon arrival at the sales location can rapidly initiate the ripening process, allowing the fruit to be available on the market as early as possible.
The following are some common plant growth regulators and their main effects:
a. Gibberellin (GA3):
Promotes growth: Gibberellin stimulates cell division and elongation in plants, thereby increasing plant height and leaf size. In the cultivation of vegetables such as celery, it makes plants more upright and leaves thicker.
Breaks dormancy: This regulator effectively breaks the dormancy state of seeds, tubers, etc., promoting germination. For example, when used on potato seed tubers, it can trigger germination earlier and accelerate seedling emergence after planting.
Promotes flowering and fruiting: Gibberellin can induce flowering in plants and increase fruit set, especially suitable for plants that require insect pollination but have poor pollination conditions. In grape cultivation, it can even increase fruit size, thereby increasing yield.
b. Auxin regulators:
Promotes rooting: Such as naphthaleneacetic acid and indolebutyric acid, commonly used for propagation by cuttings. These regulators stimulate rooting of cuttings, improving the survival rate of cuttings. They play a crucial role, especially in the propagation of woody plants.
Affecting Sex Differentiation: These regulators can alter the sex differentiation of plants, for example, increasing the number of female flowers in cucumber cultivation, thereby increasing cucumber yield.
Controlling Apical Dominance: They stimulate the growth of lateral branches, increasing branching and resulting in a fuller plant shape, which in turn increases the photosynthetic area and enhances overall growth.
c. Cytokinins:
Promoting Cell Division and Growth: Cytokinins stimulate cell division in plants, promoting bud differentiation and growth, and also aiding in wound healing and tissue culture. In floriculture, they induce the germination of lateral buds, resulting in more vigorous plants.
Delaying Senescence: These regulators slow down the senescence process of plant organs such as leaves, maintaining the plant’s greenness and vitality, and extending the ornamental or harvest period. For example, in cut flower preservation, they can significantly extend the lifespan of fresh flowers.
d. Ethephon:
(1) Ripening effect: Ethephon is widely used to ripen various fruits, such as bananas, persimmons, and tomatoes. Applying ethephon before fruit ripening can significantly accelerate the ripening process, allowing them to be marketed earlier and thus improving economic benefits.
(2) Promoting female flower differentiation: Spraying an appropriate concentration of ethephon can increase the number of female flowers in certain cucurbitaceous plants, thereby increasing the fruit set rate. For example, applying ethephon during the seedling stage of crops such as pumpkins and cucumbers can significantly increase the proportion of female flowers.
(3) Promoting abscission: Ethephon can also be used for flower and fruit thinning, causing weaker fruits to fall naturally, thus saving nutrients and improving the overall quality of the fruit. Furthermore, applying ethephon before cotton harvest can promote boll opening and lint release, simplifying the harvesting process.
e. Abscisic acid:
(1) Regulating dormancy: Abscisic acid can induce seeds to enter a dormant state, which is very useful in situations where seed preservation or extending seed dormancy is required. Simultaneously, it can break dormancy and promote seed germination, but the effect is closely related to the concentration used.
(2) Promotes abscission: Abscisic acid can accelerate the natural aging and abscission of plant organs, such as leaves, flowers, and fruits. After pruning fruit trees, the use of abscisic acid can cause leaves and twigs near the wound to fall off quickly, reducing unnecessary nutrient consumption.
(3) Enhances stress resistance: When plants face adversity such as drought, low temperature, and high temperature, the content of abscisic acid will increase, thereby regulating the physiological metabolism of plants and enhancing their stress resistance.
f. Brassinolide:
(1) Promotes growth: Brassinolide has a significant promoting effect on crop growth. It can improve the photosynthetic efficiency of plants, increase nutrient accumulation, and make plants grow stronger.
(2) Enhances stress resistance: Brassinolide can enhance the plant’s resistance to adversity such as drought, low temperature, and pests and diseases, reducing the damage of adversity to plants. For example, using brassinolide before the onset of cold weather can reduce the frost damage to plants.
(3) Synergistic Effect: When brassinolide is used in combination with other fertilizers and pesticides, it can significantly improve their effectiveness, achieving synergistic effects.
g. Triacontanol:
(1) Widely Used Fatty Alcohol: Triacontanol, as an important fatty alcohol, plays an indispensable role in agriculture, effectively promoting plant growth and development.
(2) Multiple Physiological Effects: By increasing chlorophyll content, enhancing photosynthesis, and regulating hormone levels, triacontanol can not only increase crop yield but also significantly improve its quality.
(3) Multiple Application Methods: Triacontanol can be used in various applications such as seed treatment, foliar spraying, seed soaking, and cutting treatment, aiming to improve seed germination rate and promote plant growth.
In conclusion, plant growth regulators such as triacontanol do indeed have significant effects. However, when using them, we must strictly control the concentration and method to ensure their safe and effective operation. If you encounter any questions during use, please feel free to contact me (FLYJT888) for discussion and learning. By using these plant growth regulators appropriately, we can significantly improve crop yield and quality. However, it is crucial to strictly adhere to usage guidelines to prevent any adverse effects on crops.
