Daminozide is a broad-spectrum growth retardant that can be used as a dwarfing agent, fruit-setting agent, root agent, and preservative. Its effects include inhibiting cell division and elongation, dwarfing seedlings, improving drought resistance, promoting earlier flowering in many crops, increasing fruit set, and preventing pre-harvest fruit drop.
Mechanism of Action
After being absorbed by plants, daminozide inhibits the biosynthesis of endogenous gibberellins and auxins. Its main effects are inhibiting excessive new shoot growth, shortening internode length, increasing leaf thickness and chlorophyll content, preventing flower drop and promoting fruit set, inducing adventitious root formation, stimulating root growth, and improving cold resistance.
Daminozide enters the plant through roots, stems, and leaves, exhibiting excellent systemic and conductive properties. It is transported to its sites of action via nutrient flow. In leaves, daminozide elongates palisade tissue, loosens spongy tissue, increases chlorophyll content, and enhances photosynthesis. At the plant apex, it inhibits mitosis in the apical meristem. In stems and branches, it shortens internode distance and inhibits branch elongation. Daminozide is a broad-spectrum and applicable plant growth regulator.
Efficacy and Actions
1. It slows down vegetative growth, resulting in dark green, small, and thick leaves, compact and robust plants, well-developed root systems, increased root dry weight, and a reduced crown-to-root ratio, which helps control excessive vegetative growth and flower bud differentiation.
2. It increases chlorophyll content, delays chloroplast senescence, slows growth rate, increases net photosynthetic assimilation, promotes dry matter accumulation, improves fruit quality, firmness, and fruit set, and concentrates fruit ripening.
3. It increases intracellular sugar content in plant cells, reduces energy consumption, and decreases transpiration. This may be related to daminozide's ability to enhance plant resistance to adverse environments, thus helping to reduce physiological diseases.
4. It promotes anthocyanin biosynthesis, which helps improve fruit color and prevents discoloration during storage. Daminozide is rapidly decomposed by microorganisms in the soil.
Application Method
Using daminozide can shorten internodes in grapevines, deepen leaf color, make leaves smaller and thicker, and increase chlorophyll. Daminozide's control over grape shoot growth is not as strong as that of chlormequat chloride, and its shoot-suppressing effect is also slower to appear. Experiments show that a 200 mg/L daminozide treatment is effective for Muscat grapes, while for Kyoho and Concord grapes, the concentration should be increased to 2000–3000 mg/L. Daminozide should be sprayed 7–10 days earlier than chlormequat chloride, at a concentration of 2000–3000 mg/L, determined according to the grape variety.
Precautions: When using daminozide, conduct trials on local varieties before widespread application; no phytotoxicity occurred with Kyoho grapes treated with 4000 mg/L daminozide. Spraying once with 1000 mg/L to 2000 mg/L daminozide when new shoots have 6-7 leaves can inhibit new shoot growth and increase yield. It can also be mixed with gibberellin to increase the proportion of seedless fruit, increase fruit firmness, and reduce damage during transportation.
