A method for rapid generation of leaf lettuce with light environment and nitrate nitrogen coupling

Abstract

This invention belongs to the field of crop cultivation technology and discloses a method for rapid generation of lettuce. The method involves: hydroponically cultivating lettuce seeds into seedlings, which are then transplanted after reaching the stage of two leaves and one bud; the seedlings are then cultured in a hydroponic tank with a total nitrogen nutrient solution at a nitrogen concentration of 9.0 mmol / L, a temperature of 25℃, and a light intensity maintained at 200 μmol·m² for the first 5 days. ‑2 ·s ‑1 The photoperiod is 16:8, the light quality is red:blue:far-red = 6:1:1, and the light intensity is increased to 320 μmol·m⁻¹ starting from day 6. ‑2 ·s ‑1 The photoperiod was 16:8, the light quality was red:blue:far-red = 6:1:1, and the plants were cultured for 15 days. The cultured lettuce plants were then placed in a low-nitrogen nutrient solution with a nitrogen concentration of 1.5 mmol / L at 25℃ and a light intensity of 320 μmol·m⁻¹. ‑2 ·s ‑1 The photoperiod was 20:4, and the light quality was red:blue:far-red = 6:1:1. The plants were cultured until flowering. After flowering, the nitrogen concentration of the low-nitrogen nutrient solution was adjusted to the normal nitrogen concentration of 9.0 mmol / L until the seeds matured. This invention promotes rapid flowering and seed setting in lettuce, shortens the breeding cycle, and accelerates the lettuce breeding process.

Description

Technical Field

[0001] This invention relates to the field of crop cultivation technology, specifically to a method for rapid generation of leaf lettuce coupled with light environment and nitrate nitrogen. Background Technology

[0002] Lettuce belongs to the genus *Lactuca* in the family Asteraceae. Traditional breeding processes are lengthy, requiring 180-240 days per generation and 5-8 years to develop a new variety, thus limiting the speed of new variety development. To accelerate crop breeding, researchers have developed rapid breeding generation-increasing techniques, a comprehensive technology that promotes rapid flowering and maturation by artificially controlling light and temperature. Since its introduction, this technology has received considerable attention from plant scientists. While previous research has focused on rapid breeding generation-increasing techniques for other crops, no reports have been found specifically for lettuce breeding.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] To address the problems in the background art, the present invention provides a method for rapid generation of leaf lettuce with light environment and nitrate nitrogen coupling.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for rapid generation of leaf lettuce with light environment and nitrate nitrogen coupling, comprising:

[0007] Propagate lettuce seeds in water and transplant them when the seedlings have two leaves and one heart.

[0008] Seedlings were transplanted into hydroponic tanks and cultured in a total nitrogen nutrient solution with a nitrogen concentration of 9.0 mmol / L, a temperature of 25℃, and a light intensity maintained at 200 μmol·m⁻² for the first 5 days. -2 ·s -1 The photoperiod is 16:8, the light quality is red:blue:far-red = 6:1:1, and the light intensity is increased to 320 μmol·m⁻¹ starting from day 6. -2 ·s -1 Photoperiod 16:8, light quality red:blue:far-red = 6:1:1, cultured for 15 days;

[0009] The cultured lettuce plants were placed in a low-nitrogen nutrient solution with a nitrogen concentration of 1.5 mmol / L and cultured at 25℃ and a light intensity of 277.8-416.7 μmol·m⁻². -2 ·s -1 Photoperiod 20:4, light quality red:blue:far-red = 6:1:1, cultivate until the plant flowers;

[0010] After the plant flowers, adjust the nitrogen concentration of the low-nitrogen nutrient solution to the normal nitrogen concentration of 9.0 mmol / L, keeping other conditions unchanged, until the seeds mature.

[0011] Preferably, the hydroponic seedling cultivation method is as follows: after soaking lettuce seeds, they are germinated in the dark, and after germination, they are cultured at 200 μmol·m⁻². -2 ·s -1 Cultured under light with a photoperiod of 16:8 and a light quality ratio of red to blue of 4:1. After the cotyledons unfold, cultured in a total nitrogen nutrient solution with the pH value controlled at 6.0-6.5.

[0012] Preferably, lettuce seeds are soaked for 4 hours and then sown on a sponge soaked in water, and germinated in a dark environment at 20°C for about 24 hours.

[0013] Preferably, lettuce seeds are cultured for 14 days until the seedlings have 2 leaves and 1 heart before transplanting.

[0014] Preferably, the cultured lettuce plants are cultured in a low-nitrogen nutrient solution with a nitrogen concentration of 1.5 mmol / L at a temperature of 25°C and a light intensity of 320 μmol·m⁻¹. -2 ·s -1 Photoperiod 20:4, light quality red:blue:far-red = 6:1:1, cultivate until the plant flowers.

[0015] Preferably, the molar concentrations of each element in the total nitrogen nutrient solution are: N 9.0 mmol / L, P 0.9 mmol / L, K 5.6 mmol / L, Ca 2.9 mmol / L, Mg 1.0 mmol / L, S 1.0 mmol / L, Fe 85.94 μmol / L, Mn 0.1 mmol / L, B 0.1 mmol / L, Cu 0.1 μmol / L, Zn 29.57 μmol / L, and Mo 1.05 μmol / L.

[0016] Preferably, the molar concentrations of each element in the low-nitrogen nutrient solution are: N 1.5 mmol / L, P 0.9 mmol / L, K 5.6 mmol / L, Ca 2.9 mmol / L, Mg 1.0 mmol / L, S 1.0 mmol / L, Fe 85.94 μmol / L, Mn 0.1 mmol / L, B 0.1 mmol / L, Cu 0.1 μmol / L, Zn 29.57 μmol / L, and Mo 1.05 μmol / L.

[0017] Preferably, during the period of cultivation until the plant flowers, the top of the plant is cut off in a cross shape after it forms a bulb to promote bolting.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention promotes rapid flowering and seed setting in lettuce through the synergistic management of nitrogen and light, resulting in a shorter overall growth period for lettuce, enabling faster completion of the breeding cycle, shortening the breeding time, and accelerating the lettuce breeding speed. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0021] This invention provides a method for rapid generation of leaf lettuce under light environment and nitrate nitrogen coupling, comprising:

[0022] Propagate lettuce seeds in water and transplant them when the seedlings have two leaves and one heart.

[0023] Seedlings were transplanted into hydroponic tanks and cultured in a total nitrogen nutrient solution with a nitrogen concentration of 9.0 mmol / L, a temperature of 25℃, and a light intensity maintained at 200 μmol·m⁻² for the first 5 days. -2 ·s -1 The photoperiod is 16:8, the light quality is red:blue:far-red = 6:1:1, and the light intensity is increased to 320 μmol·m⁻¹ starting from day 6. -2 ·s -1 Photoperiod 16:8, light quality red:blue:far-red = 6:1:1, cultured for 15 days;

[0024] The cultured lettuce plants were placed in a low-nitrogen nutrient solution with a nitrogen concentration of 0.8-1.8 mmol / L and cultured at 25℃ and a light intensity of 320 μmol·m⁻¹. -2 ·s -1 Photoperiod 20:4, light quality red:blue:far-red = 6:1:1, cultivate until the plant flowers;

[0025] After the plant flowers, adjust the nitrogen concentration of the low-nitrogen nutrient solution to the normal nitrogen concentration of 9.0 mmol / L, keeping other conditions unchanged, until the seeds mature.

[0026] The rapid generation method for lettuce in this invention is divided into four stages: hydroponic seedling cultivation, vegetative growth culture, low-nitrogen reproductive growth culture, and seed setting, which correspond to the four steps mentioned above.

[0027] During the vegetative growth culture phase, the light intensity was increased to 320 μmol·m⁻¹ starting from day 6. -2 ·s-1 "Adjusted light and cultured for 15 days" means that after adjusting the light, the culture is carried out for another 15 days, that is, starting from the 6th day and then cultured for another 15 days.

[0028] During the low-nitrogen reproductive growth cultivation stage, the flowering process is promoted by synergistically regulating nitrogen levels and increasing daily light intensity. Too low nitrogen or too high light intensity, in combination, can lead to excessive plant stress, increased plant mortality, or insufficient flowering and seed production. Conversely, the growth period is prolonged, failing to achieve the goal of shortening the growth period.

[0029] Specifically, the light intensity conditions for low-nitrogen (0.8-1.8 mmol / L) synergistic illumination are 277.8-416.7 μmol·m⁻². -2 ·s -1 The photoperiod ratio is 20:4, and the light quality ratio is red:blue:far-red = 6:1:1, meaning the daily light integral (DLI) is controlled to be 20-30 mol / d.

[0030] During the vegetative growth and seedling establishment stage, the nitrogen and light treatment conditions were as follows: nitrogen concentration 9.0 mmol / L, and light intensity maintained at 200 μmol·m⁻² for the first 5 days. -2 ·s -1 The photoperiod was 16:8, and the light quality was red:blue:far-red = 6:1:1. Starting from day 6, the nitrogen and light treatment conditions were: nitrogen concentration 9.0 mmol / L, light intensity 277.8-416.7 μmol·m⁻². -2 ·s -1 Photoperiod 16:8, light quality red:blue:far-red = 6:1:1, cultured for 15 days.

[0031] During the vegetative growth and seedling establishment stage, the normal nitrogen concentration range ensures rapid vegetative growth of the plant. At this stage, the light intensity should not be too strong and the photoperiod should not be too long. Since the plant's root system has not yet grown at this stage, excessive light intensity and a long photoperiod can lead to light stress and affect vegetative growth.

[0032] The following detailed description of the method and effects of rapid generation of lettuce through several specific examples. The formulations of total nitrogen nutrient solution and low nitrogen nutrient solution in the following examples are shown in Table 1.

[0033] Table 1

[0034] .

[0035] Example 1

[0036] How to quickly add generations to Zhongsheng No. 1:

[0037] (1) Sowing and seedling raising

[0038] After soaking the seeds of Zhong Sheng No. 1 for 4 hours, they were sown on a sponge soaked in water, covered, and placed in a dark environment at 20℃ for about 24 hours to promote germination. After germination, the seeds were transferred to a medium containing 200 μmol·m³. -2 ·s -1 Cultivate under light with a photoperiod of 16:8 and a light quality ratio of red to blue of 4:1. After the cotyledons unfold, use a total nitrogen nutrient solution (nutrient solution formula and element content are shown in Table 1) for cultivation, and control the pH value at 6.0-6.5. Transplant seedlings after 14 days of cultivation until they have 2 leaves and 1 bud.

[0039] (2) Vegetative growth culture

[0040] Zhong Sheng No. 1 seedlings were transplanted into hydroponic tanks and cultured in a total nitrogen nutrient solution with a nitrogen concentration of 9.0 mmol / L, a temperature of 25℃, and a light intensity maintained at 200 μmol·m⁻² for the first 5 days. -2 ·s -1 The photoperiod is 16:8, the light quality is red:blue:far-red = 6:1:1, and the light intensity is reduced to 320 μmol·m⁻¹ starting from day 6. -2 ·s -1 Photoperiod 16:8, light quality red:blue:far-red = 6:1:1, cultured for 15 days.

[0041] (3) Low-nitrogen reproductive growth culture

[0042] Replace the above two nutrient solutions with a low-nitrogen nutrient solution, with a nitrogen concentration of 1.5 mmol / L, a temperature of 25℃, and a light intensity of 320 μmol·m. -2 ·s -1 Photoperiod 20:4, light quality red:blue:far-red = 6:1:1, cultivate until the plant flowers.

[0043] (4) Seeds bear fruit

[0044] After the Zhong Sheng No. 1 plant flowers, adjust the nitrogen concentration of the three low-nitrogen nutrient solutions mentioned above to the normal nitrogen concentration of 9.0 mmol / L, while keeping other conditions unchanged, until the seeds mature.

[0045] The above breeding methods were used as the "photo-nitrogen synergistic breeding" group, and the following control groups were also set up:

[0046] Conventional open-field breeding group: open-field cultivation, natural environment.

[0047] Normal light and nitrogen breeding group: white light quality throughout the entire growth period, light intensity 200 μmol·m -2 ·s -1 Photoperiod 16:8; nitrogen concentration throughout growth period 9.0 mmol / L.

[0048] Increased light intensity for normal nitrogen propagation group: Compared with the "photo-nitrogen synergistic propagation" group, the only difference is that in step (3), the low-nitrogen nutrient solution is replaced with a full-nitrogen nutrient solution. Specifically, during the vegetative growth stage, the light intensity is maintained at 200 μmol·m for the first 5 days after transplanting. -2 ·s -1 The photoperiod is 16:8, and the light intensity is increased to 320 μmol·m on day 6. -2 ·s -1 Photoperiod 16:8, cultured for 15 days; low nitrogen-induced reproductive growth culture stage to seed maturity stage, light intensity 320 μmol·m -2 ·s -1 Photoperiod 20:4; Light quality red: blue: far red = 6:1:1 throughout the entire growth period (i.e., steps (2)-(4)); Nitrogen concentration throughout the entire growth period 9.0 mmol / L.

[0049] The conventional light-low nitrogen breeding group: compared with the "photo-nitrogen synergistic breeding" group, the only difference was the quality of white light throughout the entire growth period (i.e., steps (2)-(4)), with a light intensity of 200 μmol·m. -2 ·s -1 The photoperiod was 16:8. The reproductive period of Zhong Sheng No. 1 under different breeding methods in the above groups was statistically analyzed, and the results are shown in Table 2.

[0050] Table 2. Statistics on reproductive period of Zhong Sheng No. 1 under different breeding methods

[0051] .

[0052] Example 2

[0053] A method for quickly increasing the number of generations of head lettuce (KNV000081):

[0054] (1) Sowing and seedling raising

[0055] After soaking KNV000081 seeds for 4 hours, sow them on a water-soaked sponge, cover, and place in a dark environment at 20℃ for about 24 hours to promote germination. After germination, transfer to a 200 μmol·m³ medium solution. -2 ·s -1 Cultivate under light with a photoperiod of 16:8 and a light quality ratio of red to blue of 4:1. After the cotyledons unfold, use a total nitrogen nutrient solution (nutrient solution formula and element content are shown in Table 1) for cultivation, and control the pH value at 6.0-6.5. Transplant seedlings after 14 days of cultivation until they have 2 leaves and 1 bud.

[0056] (2) Vegetative growth culture

[0057] KNV000081 seedlings were transplanted into hydroponic tanks and cultured in a total nitrogen nutrient solution with a nitrogen concentration of 9.0 mmol / L, a temperature of 25℃, and a light intensity maintained at 200 μmol·m⁻² for the first 5 days. -2·s -1 The photoperiod is 16:8, the light quality is red:blue:far-red = 6:1:1, and the light intensity is reduced to 320 μmol·m⁻¹ starting from day 6. -2 ·s -1 Photoperiod 16:8, light quality red:blue:far-red = 6:1:1, cultured for 15 days.

[0058] (3) Low-nitrogen reproductive growth culture

[0059] Replace the above two nutrient solutions with a low-nitrogen nutrient solution, with a nitrogen concentration of 1.5 mmol / L, a temperature of 25℃, and a light intensity of 320 μmol·m. -2 ·s -1 The photoperiod ratio was 20:4, and the light quality ratio was red:blue:far-red = 6:1:1. The plants were cultivated until they flowered. During cultivation, the top of the plant was cut in a cross shape after it formed a bulb to promote bolting.

[0060] (4) Seeds bear fruit

[0061] After the KNV000081 plant flowers, adjust the nitrogen concentration of the low-nitrogen nutrient solution mentioned above to the normal nitrogen concentration of 9.0 mmol / L, while keeping other conditions unchanged, until the seeds mature.

[0062] The above breeding methods were used as the "photo-nitrogen synergistic breeding" group, and the following control groups were set up: conventional open-field breeding group, conventional normal nitrogen breeding group under normal light, normal nitrogen breeding group under increased light, and conventional low nitrogen breeding group under normal light. The setup method was the same as in Example 1.

[0063] The growth period of head lettuce KNV000081 under different propagation methods in the above groups was statistically analyzed, and the results are shown in Table 3.

[0064] Table 3. Statistics on the growth period of head lettuce KNV000081 under different propagation methods

[0065] .

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for rapid generation of leaf lettuce under light environment and nitrate nitrogen coupling, characterized in that, Include: Hydroponic cultivation of lettuce seeds is carried out until the seedlings have two leaves and one heart, at which point they are transplanted. The seedlings were transplanted into the full nitrogen nutrient solution culture in the water culture tank, the nitrogen concentration was 9.0 mmol / L, the temperature was 25℃, the light intensity was maintained at 200 μmol·m -2 ·s -1 -1 for the first 5 d, the light period was 16:8, the light quality was red:blue:far-red=6:1:1, and the light intensity was increased to 320 μmol·m -2 ·s -1 -1 from the 6th day, the light period was 16:8, the light quality was red:blue:far-red=6:1:1, and the culture lasted for 15 d; The above cultured lettuce plants were placed in low nitrogen nutrient solution with nitrogen concentration of 0.8-1.8 mmol / L, temperature of 25℃, light intensity of 277.8-416.7 μmol·m -2 ·s -1 , photoperiod of 20:4, light quality of red:blue:far red=6:1:1, and cultured until the plants flowered; After the plant flowers, adjust the nitrogen concentration of the low-nitrogen nutrient solution to the normal nitrogen concentration of 9.0 mmol / L, keeping other conditions unchanged, until the seeds mature; The hydroponic seedling cultivation method involves soaking lettuce seeds and then germinating them in the dark. After germination, the seeds are cultured at 200 μmol·m⁻² ... -2 ·s -1 Cultured under light with a photoperiod of 16:8 and a light quality ratio of red to blue of 4:

1. After the cotyledons unfold, cultured in a total nitrogen nutrient solution with the pH value controlled at 6.0-6.

5. The molar concentrations of each element in the total nitrogen nutrient solution were: N 9.0 mmol / L, P 0.9 mmol / L, K 5.6 mmol / L, Ca 2.9 mmol / L, Mg 1.0 mmol / L, S 1.0 mmol / L, Fe 85.94 μmol / L, Mn 0.1 mmol / L, B 0.1 mmol / L, Cu 0.1 μmol / L, Zn 29.57 μmol / L, and Mo 1.05 μmol / L. The molar concentrations of each element in the low-nitrogen nutrient solution were as follows: N 1.5 mmol / L, P 0.9 mmol / L, K 5.6 mmol / L, Ca 2.9 mmol / L, Mg 1.0 mmol / L, S 1.0 mmol / L, Fe 85.94 μmol / L, Mn 0.1 mmol / L, B 0.1 mmol / L, Cu 0.1 μmol / L, Zn 29.57 μmol / L, and Mo 1.05 μmol / L.

2. The method as described in claim 1, characterized in that, Soak lettuce seeds for 4 hours, then sow them on a sponge soaked in water and germinate them in a dark environment at 20°C for about 24 hours.

3. The method as described in claim 1, characterized in that, Lettuce seeds are cultured for 14 days until the seedlings have 2 leaves and 1 heart before transplanting.

4. The method as described in claim 1, characterized in that, The cultured lettuce plants were placed in a low-nitrogen nutrient solution with a nitrogen concentration of 1.5 mmol / L and cultured at a temperature of 25℃ and a light intensity of 320 μmol·m. -2 ·s -1 Photoperiod 20:4, light quality red:blue:far-red = 6:1:1, cultivate until the plant flowers.

5. The method as described in claim 1, characterized in that, During the cultivation period until the plant flowers, after the plant forms a bulb, cut off the top of the bulb in a cross shape to promote bolting.