How can plant growth regulators be used safely?
How can plant growth regulators be used safely? Please provide an introduction to the methods of use. Plant hormones are organic small-molecule substances synthesized within plants at extremely low concentrations that have significant effects on plant growth and development, and are also called natural plant hormones or endogenous plant hormones. Plant hormones can be divided into corn, namely auxins, gibberell...
How can plant growth regulators be used safely? Please provide an introduction to the methods of use
Plant hormones are organic small-molecule substances synthesized within plants at extremely low concentrations that have significant effects on plant growth and development, and are also called natural plant hormones or endogenous plant hormones. Plant hormones can be divided into corn, namely auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Plant hormones play an important regulatory and controlling role in plant growth and development, such as affecting plant germination, rooting, flowering and differentiation, and affecting plant germination, rooting, flowering, fruiting, dormancy, abscission, and so on.
Because hormones produced autonomously within most plants are easily decomposed, more than 95% of the hormones used in production are artificially synthesized. Such substances are called growth regulators. They are used not only in crop production, but also for post-harvest preservation and ripening of fruits and vegetables.
As analogs of natural plant hormones, plant growth regulators are generally slightly toxic or low in toxicity. Although they are not intended to kill harmful organisms and can only regulate plant growth and germination, they are still managed uniformly as a category of pesticides.
The following mainly introduces the use of several plant growth regulators:
1. 2,4-D is the abbreviation of 2,4-dichlorophenoxyacetic acid. It has a relatively low cost and is widely used. At low concentrations, farmers use it for seed soaking and sprout promotion, which can increase the germination rate; at medium concentrations (1-25 milliliters/liter), spraying it when orange and pear trees bloom can prevent flower and fruit drop and induce the production of seedless fruit. When oranges mature, it can also be used to soak citrus for preservation; at higher concentrations, it can kill many broadleaf weeds, and glyphosate can also be added to increase efficacy in killing weeds.
2. The main effects of naphthalene acetic acid are stimulating growth, rooting of cuttings, flower and fruit thinning, preventing flower and fruit drop, inducing flowering, inhibiting sprouting, and promoting early maturity and increasing yield. Farmers in our town generally spray it on tomatoes and cucumbers to prevent flower drop and promote fruit set. It is more often used for cuttings of osmanthus and grape seedlings. Before cuttings, the base is soaked 2 cm and soaked for 2-3 hours before cuttings. Some farmers use it as a rooting agent. 2.5 grams of 20% naphthalene acetic acid is mixed with 20 jin of water, or applied by pouring to soak the roots, to promote early rooting and more root growth in camphor trees and magnolia trees and improve the survival rate.
3. Gibberellin, also known as 920, is a broad-spectrum plant growth regulator that can promote plant growth and development, increase yield, improve quality, promote germination, reduce fruit drop, and increase fruit set rate. The earliest contact farmers in our town had with 920 was for spraying at the heading and flowering stage, which can complete heading within two or three days and reduce the harm caused by the "Cold Dew wind." However, if the concentration is too high, it can lengthen internodes and easily cause lodging. Later, it was gradually replaced with safer fertilizers such as grain-filling fertilizer and grain plumpness fertilizer. These contain a small amount of 920 and also contain fertilizers such as potassium dihydrogen phosphate, and can similarly make rice seedlings head uniformly and improve the seed-setting rate.
4. Ethephon is an artificially synthesized low-toxicity plant growth regulator that works by releasing ethylene. Ethephon promotes earlier coloring and ripening of fruits and vegetables, storage and preservation, and de-astringency. It can also regulate the flowering period, promote earlier coloring and ripening of melon vegetables, shorten the crop growth period, and increase yield. Some farmers in our town use it by spraying it on melon crops and tomatoes, and it is also used a lot on fruit trees, such as citrus. During the color-turning stage of citrus, spraying about 150 mg/kg of ethephon on the canopy can make citrus mature 1-2 weeks earlier. Ethephon has strong physiological activity and must not be used indiscriminately, so as to avoid phytotoxicity.
5. Forchlorfenuron, as a swelling agent, is often used on melons, vegetables, and fruits. It has the strongest activity and can accelerate cell division, promote cell enlargement and differentiation, and prevent flower and fruit drop. Farmers in our town often use it by spraying it on watermelons, cucumbers, citrus, and grapes. Spraying 1-2 times before and after flowering can bring them to market earlier and increase yield. When used on vegetables, it is generally sprayed on lettuce.
In recent years, Tianfengsu, broadcast on rural channels, is also a plant regulator. Its main component is brassinolide. It can be used for seed soaking. During the rice seedling stage and tillering stage, heading and flowering stage, and grain-filling stage, it can be mixed with pesticides and sprayed once a month. It can advance heading, improve the seed-setting rate, increase the 1000-grain weight, and increase yield. It can make rice mature 4-7 days earlier and reduce the harm caused by the "Cold Dew wind." It can also be sprayed on vegetables to bring them to market one week earlier.
Although plant growth regulators are low in toxicity, they are still pesticides after all, and cases of harm caused by excessive use occur from time to time, such as the "watermelon splitting" incident in Jiangsu, and cucumbers and loofahs growing thicker and longer in refrigerators. The amount of residue should be reduced as much as possible, and plant growth regulators with fast decomposition, short residual periods, and low toxicity should be selected. Under the premise of the same effect, regulators with short residual periods and low toxicity should be selected. For example, for the dwarfing agent chlormequat on seedlings, uniconazole can be used instead of paclobutrazol. The two have the same physiological functions, but uniconazole has high activity, a short residual period, and is safe. Second, the correct concentration, frequency, and timing of use must be mastered. Third, improve efficacy and reduce dosage. It is necessary to maximize the role of regulators, greatly improve crop yield and quality, and even more ensure the quality and safety of agricultural products.
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