Scientific and Rational Use of Plant Growth Regulators
Plant growth regulators are diverse in type and characteristics. To fully utilize their functions in production, it is essential to understand the performance of each regulator and the problems that need to be addressed in production.
(I) Factors Affecting the Effectiveness of Plant Growth Regulators
1. Climate
Temperature affects the effectiveness of plant growth regulators. Phenoxyacetic acid regulators such as S-ABA and DTCPA have strict temperature requirements; excessively high or low temperatures will cause adverse effects.
2. Plant Growth Regulator Concentration
An important characteristic of plant growth regulators is that some are both regulators and herbicides. At lower concentrations, they regulate plant growth, while at higher concentrations, they act as weed control. Therefore, it is crucial to correctly select plant growth regulators and their concentrations.
3. Crops
The appropriate concentration of each growth regulator varies depending on the crop, and even the same concentration can have different effects on different organs of the same crop. For example, ethephon at a concentration of 1000 mg/kg on rice seedlings will not cause phytotoxicity, but spraying it on hawthorn can cause leaf drop. Similarly, 2,4-D, a fruit-setting agent for tomatoes, is commonly used at a concentration of 10 mg/kg; it does not cause phytotoxicity to petals but does to leaves. Therefore, different crops have different sensitivities to different plant growth regulators, and appropriate plant growth regulators should be selected according to the different needs of each crop.
4. Cultivation Management
The use of plant growth regulators is closely related to cultivation management. For example, treating weak wheat fields with lodging-resistant plant growth regulators often does not yield good results. Increased water and fertilizer management is needed to promote vigorous growth. Significant effects are only achieved when used on overly vigorous crops. For instance, paclobutrazol used on late-season rice seedlings in continuous cropping can cause heading problems if the seedlings are pulled out, but if the seedbed is tilled and transplanted, it will not affect the subsequent crop.
(II) Correct Use of Plant Growth Regulators
1. Correct Selection of Applicable Growth Regulators
Selecting suitable growth regulators is a prerequisite. When choosing, the following points should be noted:
First, understand the basic properties of growth regulators. Currently, over 400 agents with plant physiological regulating functions have been discovered. Since each regulator has its own physicochemical properties, mechanism of action, and applicable crops, it is essential to understand the key points and precautions before use.
Second, clarify the purpose of using the growth regulator. Commonly used growth regulators have functions such as promoting root growth, inhibiting growth, protecting flowers and fruits, increasing sugar content, killing male reproductive organs, and accelerating ripening. However, each crop has different physiological requirements at different growth stages. Therefore, selection and rational use should be based on the specific crop and growth stage.
Third, ensure proper mixing of plant growth regulators. For example, mixing Naphthyl Acetic Acid with Indole-3-Butyric Acid (IBA) can enhance the root-promoting effect on plants.
Fourth, conduct thorough trials and demonstrations of plant growth regulators. The use of plant growth regulators is often influenced by geographical and climatic conditions, and the dosage and concentration should vary between regions. For plant growth regulators never used before, trials should be conducted before application.
Fifth, pay attention to the product quality of plant growth regulators to prevent the introduction of counterfeit or substandard plant growth regulators.
2. Correctly Prepare the Applicable Concentration of Plant Growth Regulators
Third, determine the application concentration based on the temperature.
Fourth, accurately prepare the concentration based on the effective components of the plant growth regulator. Because there are many types of plant growth regulators with varying effective component contents (e.g., 85% GA crystals, 4% GA emulsion), the concentration should be diluted with an appropriate amount of water according to the effective components during preparation.
3. Correctly Master the Application Methods of Plant Growth Regulators
The methods of applying plant growth regulators usually include spraying, spot application, and dipping.
(1) Spraying: When using the spraying method, in addition to mastering the appropriate timing and concentration, it is also necessary to select suitable fields for spraying. For example, when spraying cotton with plant growth regulators such as chlormequat chloride or mepiquat chloride, choose fields with vigorous stem and leaf growth.
(2) Spot application: When applying plant growth regulators by spot application, select the appropriate plant growth regulator and concentration, and avoid spot application at high temperatures.
(3) Dipping: When applying plant growth regulators by dipping, pay attention to the relationship between concentration and environment. For example, when the air is dry, the evaporation of branches and leaves is high, so the concentration should be appropriately increased and the dipping time shortened to avoid excessive absorption by the cuttings and causing phytotoxicity. Secondly, pay attention to the cutting temperature. Generally, the optimal temperature for rooting and sprouting is 20-30℃. Thirdly, manage the cuttings after the application of plant growth regulators. It is best to place the cuttings in well-ventilated, well-drained sandy soil or fine sand, and prevent direct sunlight.
4. Properly manage the plant growth regulators after application.
For crops using plant growth regulators, management should be carried out according to the crop growth characteristics and the specific requirements of the plant growth regulator.
(I) Factors Affecting the Effectiveness of Plant Growth Regulators
1. Climate
Temperature affects the effectiveness of plant growth regulators. Phenoxyacetic acid regulators such as S-ABA and DTCPA have strict temperature requirements; excessively high or low temperatures will cause adverse effects.
2. Plant Growth Regulator Concentration
An important characteristic of plant growth regulators is that some are both regulators and herbicides. At lower concentrations, they regulate plant growth, while at higher concentrations, they act as weed control. Therefore, it is crucial to correctly select plant growth regulators and their concentrations.
3. Crops
The appropriate concentration of each growth regulator varies depending on the crop, and even the same concentration can have different effects on different organs of the same crop. For example, ethephon at a concentration of 1000 mg/kg on rice seedlings will not cause phytotoxicity, but spraying it on hawthorn can cause leaf drop. Similarly, 2,4-D, a fruit-setting agent for tomatoes, is commonly used at a concentration of 10 mg/kg; it does not cause phytotoxicity to petals but does to leaves. Therefore, different crops have different sensitivities to different plant growth regulators, and appropriate plant growth regulators should be selected according to the different needs of each crop.
4. Cultivation Management
The use of plant growth regulators is closely related to cultivation management. For example, treating weak wheat fields with lodging-resistant plant growth regulators often does not yield good results. Increased water and fertilizer management is needed to promote vigorous growth. Significant effects are only achieved when used on overly vigorous crops. For instance, paclobutrazol used on late-season rice seedlings in continuous cropping can cause heading problems if the seedlings are pulled out, but if the seedbed is tilled and transplanted, it will not affect the subsequent crop.
(II) Correct Use of Plant Growth Regulators
1. Correct Selection of Applicable Growth Regulators
Selecting suitable growth regulators is a prerequisite. When choosing, the following points should be noted:
First, understand the basic properties of growth regulators. Currently, over 400 agents with plant physiological regulating functions have been discovered. Since each regulator has its own physicochemical properties, mechanism of action, and applicable crops, it is essential to understand the key points and precautions before use.
Second, clarify the purpose of using the growth regulator. Commonly used growth regulators have functions such as promoting root growth, inhibiting growth, protecting flowers and fruits, increasing sugar content, killing male reproductive organs, and accelerating ripening. However, each crop has different physiological requirements at different growth stages. Therefore, selection and rational use should be based on the specific crop and growth stage.
Third, ensure proper mixing of plant growth regulators. For example, mixing Naphthyl Acetic Acid with Indole-3-Butyric Acid (IBA) can enhance the root-promoting effect on plants.
Fourth, conduct thorough trials and demonstrations of plant growth regulators. The use of plant growth regulators is often influenced by geographical and climatic conditions, and the dosage and concentration should vary between regions. For plant growth regulators never used before, trials should be conducted before application.
Fifth, pay attention to the product quality of plant growth regulators to prevent the introduction of counterfeit or substandard plant growth regulators.
2. Correctly Prepare the Applicable Concentration of Plant Growth Regulators
Third, determine the application concentration based on the temperature.
Fourth, accurately prepare the concentration based on the effective components of the plant growth regulator. Because there are many types of plant growth regulators with varying effective component contents (e.g., 85% GA crystals, 4% GA emulsion), the concentration should be diluted with an appropriate amount of water according to the effective components during preparation.
3. Correctly Master the Application Methods of Plant Growth Regulators
The methods of applying plant growth regulators usually include spraying, spot application, and dipping.
(1) Spraying: When using the spraying method, in addition to mastering the appropriate timing and concentration, it is also necessary to select suitable fields for spraying. For example, when spraying cotton with plant growth regulators such as chlormequat chloride or mepiquat chloride, choose fields with vigorous stem and leaf growth.
(2) Spot application: When applying plant growth regulators by spot application, select the appropriate plant growth regulator and concentration, and avoid spot application at high temperatures.
(3) Dipping: When applying plant growth regulators by dipping, pay attention to the relationship between concentration and environment. For example, when the air is dry, the evaporation of branches and leaves is high, so the concentration should be appropriately increased and the dipping time shortened to avoid excessive absorption by the cuttings and causing phytotoxicity. Secondly, pay attention to the cutting temperature. Generally, the optimal temperature for rooting and sprouting is 20-30℃. Thirdly, manage the cuttings after the application of plant growth regulators. It is best to place the cuttings in well-ventilated, well-drained sandy soil or fine sand, and prevent direct sunlight.
4. Properly manage the plant growth regulators after application.
For crops using plant growth regulators, management should be carried out according to the crop growth characteristics and the specific requirements of the plant growth regulator.
