Plant growth regulators use on lettuce

1. Breaking seed dormancy
The optimum temperature for germination of lettuce seeds is 15-29℃. Above 25℃, the germination ability is significantly reduced under lightless conditions. Seeds that break dormancy can improve their germination ability under high temperatures. When the soil temperature reaches 27℃, lettuce seeds can usually be induced to dormant.

Thiourea
Treatment with 0.2% Thiourea resulted in a germination rate of 75%, while the control was only 7%.

Gibberellic Acid GA3
Treatment with Gibberellic Acid GA3 100mg/L solution resulted in germination of about 80%.

Kinetin
Soaking seeds with 100mg/L kinetin solution for 3min can overcome dormancy under high temperatures. When the temperature reaches 35℃, the effect of kinetin is more significant.

2: Inhibit bolting
Daminozide
When lettuce begins to grow, spray the plants with 4000-8000mg/L Daminozide 2-3 times, once every 3-5 days, which can significantly inhibit bolting, increase the thickness of the stems, and improve the commercial value.

Maleic hydrazide
During the growth of lettuce seedlings, treatment with Maleic hydrazide 100mg/L solution can also inhibit bolting and flowering.

3: Promote bolting
Gibberellic Acid GA3
Lettuce is the only leaf and root vegetable that can promote bolting under warm and long-day conditions due to high temperature induction of flower bud differentiation. Treating seeds with long-day and low temperature can promote flower formation, but seed preservation requires a cool climate. For example, in the artificial climate chamber test, within 10-25℃, both short-day and long-day can bolt and bloom; below 10-15℃ or above 25℃, fruiting is poor and the seed reserve is reduced; on the contrary, the seed reserve is the largest at 10-15℃. It is difficult to reserve lettuce seeds, and spraying Gibberellic Acid GA3 can promote bolting of lettuce and reduce rot.

Gibberellic Acid GA3
When the cabbage lettuce has 4-10 leaves, spraying 5-10mg/L Gibberellic Acid GA3 solution can promote bolting and flowering of cabbage lettuce before cabbage, and the seeds mature 15 days earlier, increasing seed yield.

4 Promote growth
Gibberellic Acid GA3
The optimum temperature for lettuce seedlings is 16-20℃, and the optimum temperature for continuous setting is 18-22℃. If the temperature exceeds 25℃, lettuce will easily grow too tall. The light in greenhouses and sheds in winter and spring can meet the normal growth of lettuce. Water should be controlled during the continuous setting period, and sufficient water should be supplied during the heading period. For lettuce with edible tender stems, when the plant has 10-15 leaves, spray with 10-40mg/L of gibberellin.

After treatment, the differentiation of heart leaves is accelerated, the number of leaves increases, and the tender stems are accelerated to elongate. It can be harvested 10 days earlier, increasing the yield by 12%-44.8%. Leaf lettuce is treated with 10mg/L of gibberellin 10-15 days before harvest, and the plant grows fast, which can increase the yield by 10%-15%. When applying gibberellins on lettuce, attention should be paid to the concentration used to avoid spraying too high a concentration, which will lead to slender stems, reduced fresh weight, lignification in the later stage, and reduced quality.

It is also necessary to avoid spraying when the seedlings are too small, otherwise the stems will be slender, bolting will occur early, and the economic value will be lost.

DA-6 (Diethyl aminoethyl hexanoate)
Spraying lettuce with a 10mg/L DA-6 (Diethyl aminoethyl hexanoate) solution can also make the seedlings have a developed root system and thick stems, generally increasing production by 25%-30%.

5. Chemical preservation
6-Benzylaminopurine (6-BA)
Like most vegetables, lettuce senescence is the gradual yellowing of leaves after harvest, followed by the gradual disintegration of tissues, becoming sticky and rotting. Spraying the field with 5-10mg/L 6-Benzylaminopurine (6-BA) before harvest can extend the time that the lettuce remains fresh green after packaging by 3-5 days. Treatment with 6-BA after harvest can also delay senescence. Spraying lettuce with 2.5-10 mg/L 6-BA 1 day after harvest has the best effect. If the lettuce is first stored at 4°C for 2-8 days, then sprayed with 5 mg/L 6-BA on the leaves and stored at 21°C, after 5 days of treatment, only 12.1% of the control can be marketed, while 70% of the treated can be marketed.

Daminozide
Immersing leaves and lettuce stems with 120 mg/L Daminozide solution has a good preservation effect and prolongs storage time.

Chlormequat Chloride (CCC)
Immersing leaves and lettuce stems with 60 mg/L Chlormequat Chloride (CCC) solution has a good preservation effect and prolongs storage time.