Method for enhancing stress resistance of pepper seedlings under stress of low temperature and weak light

Abstract

The invention relates to a method for enhancing stress resistance of pepper seedlings under low temperature and weak light stress, a zeatin solution with a specific concentration is uniformly sprayed on leaves of the pepper seedlings before the pepper seedlings suffer from low temperature and weak light stress, and results show that zeatin treatment can help the pepper seedlings maintain a relatively normal growth state under low temperature and weak light; according to the method, chlorophyll fluorescence parameters are remarkably improved, active oxygen accumulation is reduced, antioxidant enzyme activity is remarkably improved, so that the stress resistance of the pepper seedlings is enhanced, and the method is low in cost, easy and convenient to operate, capable of facilitating large-area efficient production of the pepper seedlings and significant to annual production and supply of peppers.

Description

Technical Field

[0001] The invention belongs to the technical field of pepper cultivation, and particularly relates to a method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress. Background Art

[0002] chili( Capsicum annuum L.) is native to South America. Due to its important economic and nutritional value, it has become the largest vegetable crop in my country. At the same time, because it likes warmth and light, it is also one of the main vegetable crops cultivated in facilities in my country. Since most parts of my country are mainly plastic greenhouses, the controllability of temperature and light is poor, which makes it difficult for the temperature and light conditions in the facilities to achieve the optimal conditions for the growth and development of peppers. Especially in early spring and winter production, pepper seedlings are extremely susceptible to low temperature and weak light stress, and growth indicators such as plant height, stem thickness, leaf area, and root system will show a downward trend; photosynthesis is weakened, and organic matter accumulation is reduced; at the same time, a large amount of intracellular reactive oxygen is produced, and it reacts with unsaturated fatty acids on the cell membrane to produce malondialdehyde (MDA), destroying the structure and function of membrane proteins, resulting in a series of abnormal physiological and biochemical reactions (Zhang et al., 2020; Li et al., 2022; Ding et al., 2022;), which ultimately causes serious damage to the yield and quality of peppers. It has now become a key limiting factor for off-season production of peppers.

[0003] Although the need for temperature and light can be met by electric heating and LED supplementary lighting in production, it will increase the cost and reduce the economic benefits in actual production. Therefore, developing a low-cost, simple and efficient method to improve the resistance of pepper seedlings to low temperature and weak light is of great significance to the efficient cultivation and year-round supply of pepper. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress, which can effectively reduce the harm caused by low temperature and weak light in off-season production of pepper.

[0005] To achieve the above object, the technical solution adopted by the present invention is a method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress, which specifically comprises the following steps: (1) Select plump pepper seeds, sterilize them with 5% NaClO for 15 min, soak them for 4 h, and then place them in a 28 ℃ constant temperature incubator for germination. Sow the seeds after they turn white. (2) When the peppers have four leaves and one bud, spray the front and back sides of each pepper leaf with zeatin solution evenly at 20:00 every day until water droplets are about to drip. Continue spraying for 4 days. The concentration of zeatin solution used is 50-250 μmol / L. (3) After foliar spraying of zeatin, the plants were placed in a light incubator for low-temperature and weak-light treatment. The specific conditions were: temperature 10°C / 5°C, light intensity 100 μmol m -2 s -1 The photoperiod was 12 h / 12 ​​h (day / night) and the treatment was for 7 days. After the treatment, relevant growth indicators and physical and chemical indicators were tested.

[0006] Preferably, the step (2) further comprises the following steps: (2.1) Zeatin was fully dissolved in anhydrous ethanol and then diluted with ddH2O to different concentrations of zeatin solution. A total of 0 μmol / L, 50 μmol / L, 100 μmol / L, 150 μmol / L, 200 μmol / L, and 250 μmol / L concentration gradients were set. A control group (CK) was set up: the cells were sprayed with ddH2O and placed under normal temperature and light conditions [temperature 28℃ / 18℃, light intensity 300μmol m -2 s -1 , photoperiod 12 h / 12 ​​h (day / night)]; (2.2) The pepper variety used is Yangjiao No. 2; (2.2) At 20:00 every day, spray the leaves of Yangjiao No. 2 seedlings with four leaves and one heart evenly with zeatin solution until water drops are dripping, and continue spraying for 4 days; Preferably, the step (3) further comprises the following steps: (3.1) After the low temperature and weak light treatment, the growth indicators such as plant height, stem diameter, leaf area, and root length of pepper seedlings after foliar spraying of different concentrations of zeatin were tested to reflect the effect of zeatin on the growth of pepper seedlings under low temperature and light stress; (3.2) After the low temperature and weak light treatment, the chlorophyll fluorescence parameters of pepper seedlings after foliar spraying of different concentrations of zeatin were measured, mainly including: the maximum photosynthetic efficiency of photosystem II (Fv / Fm), the actual photosynthetic efficiency of photosystem II Y(II), and the photochemical quenching coefficient qP, to reflect the effect of zeatin on the photosynthesis of pepper seedlings under low temperature and weak light stress; (3.3) After the low temperature and weak light treatment, the pepper seedlings were sprayed with different concentrations of zeatin on the leaves and the active oxygen was detected, mainly including hydrogen peroxide (H2O2) and superoxide anion (O2 - ), to reflect the effect of zeatin on the accumulation of active oxygen in pepper seedlings under low temperature and weak light stress; (3.4) After the low temperature and weak light treatment, the antioxidant enzyme activities of pepper seedlings after foliar spraying of different concentrations of zeatin were detected, mainly including: peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), to reflect the effect of zeatin on the antioxidant enzyme system of pepper seedlings under low temperature and weak light stress.

[0007] The applicant found that the zeatin solution of the present invention can effectively enhance the stress resistance of pepper seedlings under low temperature and weak light stress. The optimal zeatin solution concentration is 150 μmol / L. At this solution concentration, various detection indicators are significantly higher than other concentrations and close to CK.

[0008] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress. Before the pepper seedlings are subjected to low temperature and weak light stress, a zeatin solution of a specific concentration is sprayed on the front and back sides of the leaves of the pepper seedlings, which can significantly enhance the resistance of the pepper seedlings to low temperature and weak light. The results show that 150 μmol / L zeatin solution significantly improves the growth indicators of peppers such as plant height, stem thickness, leaf area, and root length under low temperature and weak light stress; significantly improves the chlorophyll photosynthetic parameters such as Fv / Fm, Y(II), and qP of peppers under low temperature and weak light stress; and significantly reduces the concentration of H2O2 and O2 - The accumulation of active oxygen such as zeatin and zeatin can be reduced; the activity of antioxidant enzymes such as POD, CAT, and SOD is significantly increased. Therefore, spraying pepper seedlings with zeatin solution can effectively enhance the pepper's resistance to low temperature and weak light stress. This method has low investment cost and is easy to operate. It can help pepper seedlings to be produced efficiently on a large scale, which is of great significance to the year-round production and supply of pepper. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The different appearances of pepper seedlings under low temperature and weak light stress after being sprayed with different concentrations of zeatin solution; Figure 2 Changes in growth indicators of pepper seedlings under low temperature and weak light stress after spraying zeatin solution with different concentrations: A. Changes in plant height of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; B. Changes in stem diameter of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; C. Changes in leaf area of ​​pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; D. Changes in root length of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution.

[0010] Figure 3Changes in chlorophyll fluorescence parameters of pepper seedlings under low temperature and weak light stress after spraying zeatin solution with different concentrations: A. Changes in Fv / Fm of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; B. Changes in Y(II) of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; C. Changes in qP of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution.

[0011] Figure 4 Figure 2. Changes in active oxygen content in pepper seedlings under low temperature and weak light stress after spraying different concentrations of zeatin solution: A. Changes in H2O2 in pepper seedlings under low temperature and weak light stress after zeatin solution treatment; B. Changes in O2 in pepper seedlings under low temperature and weak light stress after zeatin solution treatment - changes.

[0012] Figure 5 Changes in antioxidant enzyme activities of pepper seedlings under low temperature and weak light stress after spraying different concentrations of zeatin solution: A. Changes in POD of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; B. Changes in CAT of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution; C. Changes in SOD of pepper seedlings under low temperature and weak light stress after treatment with zeatin solution.

[0013] Different lowercase letters in the figure indicate significant differences among treatments ( P <0.05). DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described in detail below in conjunction with the embodiments. It is necessary to point out that the following embodiments are only used to explain and illustrate the present invention and are not used to limit the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content still belong to the protection scope of the present invention. Example 1

[0015] The experiment was conducted in 2024 at the Jiangsu (Hanjiang) Modern Agriculture (Vegetable) Science and Technology Comprehensive Demonstration Base (119°4' east longitude, 32°49' north latitude), using "Yangjiao No. 2" as the material. The effect of spraying zeatin solution on the growth of pepper seedlings under low temperature and weak light stress was studied, and a method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress was developed.

[0016] Test methods Select plump pepper seeds, disinfect them with 5% NaClO for 15 min, soak them for 4 h, and then place them in a 28 ℃ constant temperature incubator for germination. After the seeds turn white, sow them in 72-hole black plastic plug trays. The substrate ratio is peat: vermiculite: perlite = 3:1:1 (volume ratio). When the pepper seedlings have two leaves and one heart, move them into 7 cm×7 cm plastic nutrient pots for routine seedling management. When the seedlings grow to 6 true leaves, select seedlings with consistent growth for exogenous zeatin treatment. The experiment adopts a randomized block design, with a total of 6 different concentration treatments (see Table 1 for details), each treatment is repeated 3 times, with 30 seedlings per repeat, and a total of 90 seedlings / treatment. At 20:00 every day, the front and back sides of each pepper leaf were sprayed evenly until water droplets were about to drip. The spraying was continued for 4 days, and then the plants were placed in an artificial climate chamber (Nanjing Lisi Gao Instrument Equipment Co., Ltd., RGD-1000C) to simulate a low temperature and weak light environment: temperature 10℃ / 5℃, light intensity 100 μmol m -2 s -1 , 12 h / 12 ​​h (day / night), and related traits were tested 7 days after treatment.

[0017] Table 1 Exogenous zeatin concentration setting Table 1 Exogenous zeatin concentration setting deal with Concentration (μmol / L) T1 0 T2 50 T3 100 T4 150 T5 200 T6 250 CK 0 Note: CK specifically refers to: spraying ddH2O and placing under normal temperature and light conditions [temperature 28℃ / 18℃, light intensity 300μmol m -2 s -1 , photoperiod 12 h / 12 ​​h (day / night)].

[0018] Detection Methods 2.1 Growth index observation: Pepper plants after different treatments were observed and photographed; plant height (length from the base of the plant to the growth point) and root length (complete root system after washing) were measured with a ruler; stem diameter (lower part of cotyledon) was measured with a vernier caliper; leaf area was determined using ImageJ software (Bethesda, USA).

[0019] 2.2 Detection of chlorophyll fluorescence parameters: A chlorophyll fluorescence imaging system (PlantView 230F, Guangzhou Bolu Technology Co., Ltd.) was used to detect the chlorophyll fluorescence parameters of the plants. Each pepper plant was cultured in the dark for 30 min before the corresponding parameters were measured.

[0020] 2.3 Reactive oxygen species determination: H2O2 and O2 were determined by spectrophotometry using a kit (Beijing Solebow Technology Co., Ltd.) - The content.

[0021] 2.4 Antioxidant enzyme activity detection: POD, SOD, and CAT activities were determined by spectrophotometry using a kit (Beijing Solebow Technology Co., Ltd.).

[0022] (III) Test results 3.1 Effects of spraying different concentrations of zeatin solution on growth indicators of pepper seedlings under low temperature and weak light stress Depend on Figure 1 It can be seen that after spraying different concentrations of zeatin solution, pepper seedlings showed different growth conditions under low temperature and weak light stress. Compared with CK, leaves drooped severely after T1 treatment, some leaves drooped after T2 and T3 treatments, leaves drooped the least after T4 treatment, leaves drooped slightly after T5 treatment, and leaves drooped more severely after T6 treatment. Statistics of various growth indicators were obtained. Figure 2 It can be seen that under low temperature and weak light stress, with the increase of zeatin solution concentration, the growth indicators of pepper seedlings showed a trend of first increasing and then decreasing, and the treatment effect was best at a concentration of 150 μmol / L.

[0023] 3.2 Effects of spraying different concentrations of zeatin solution on chlorophyll fluorescence parameters of pepper seedlings under low temperature and weak light stress Depend on Figure 3 It can be seen that after spraying different concentrations of zeatin solution, the chlorophyll fluorescence parameters of pepper seedlings decreased to varying degrees compared with CK. As the concentration of zeatin solution increased, Fv / Fm, Y(II) and qP all showed a trend of first increasing and then decreasing. When the concentration of zeatin solution was 150 μmol / L, Fv / Fm, Y(II) and qP all reached their maximum values.

[0024] 3.3 Effects of spraying different concentrations of zeatin solution on active oxygen in pepper seedlings under low temperature and weak light stress Depend on Figure 4 It can be seen that after spraying different concentrations of zeatin solution, the active oxygen content of pepper seedlings increased to varying degrees compared with CK. - It showed a trend of decreasing first and then increasing. When the concentration of zeatin solution was 150 μmol / L, O2 - The content of H2O2 is the lowest; the change trend of H2O2 is similar to that of O2 - Similar, but the overall increase is lower than O2 - .

[0025] 3.4 Effects of spraying different concentrations of zeatin solution on antioxidant enzyme activities of pepper seedlings under low temperature and weak light stress Depend on Figure 5It can be seen that after low temperature and weak light stress, the antioxidant enzymes of pepper seedlings increased to varying degrees to remove reactive oxygen and protect the cell membrane from damage. At the same time, after treatment with zeatin solution, the activity of antioxidant enzymes was promoted. The effects of different solution concentrations were different, but POD, CAT and SOD were all best at 150 μmol / L. At this concentration, they were increased by 365.35%, 331.57% and 178.94% respectively compared with CK, and were significantly higher than other concentrations.

[0026] In summary, spraying zeatin solution can effectively enhance the stress resistance of pepper seedlings under low temperature and weak light stress, and the best concentration of zeatin solution is 150 μmol / L.

Claims

1. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress, characterized in that: The method comprises the following steps: (1) Select plump pepper seeds, sterilize them with 5% NaClO for 15 min, soak them for 4 h, and then place them in a 28 ℃ constant temperature incubator for germination. Sow the seeds after they turn white. (2) When the peppers have four leaves and one bud, spray the front and back sides of each pepper leaf evenly with zeatin solution at 20:00 every day until water droplets are about to drip. Continue spraying for 4 days. The concentration of the zeatin solution used should be 50-250 μmol / L.

2. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 1, characterized in that: The specific conditions of low temperature and weak light stress are: temperature 10℃ / 5℃, light intensity 100 μmol m -2 s -1 The photoperiod was 12 h / 12 ​​h (day / night) and the treatment was for 7 days. After the treatment, relevant growth indicators and physical and chemical indicators were tested.

3. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 1, characterized in that: The preparation method of the zein solution used is: firstly dissolve the zein fully with anhydrous ethanol, and then dilute it with ddH2O to form zein solutions of different concentrations.

4. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 1 or 3, characterized in that: The treatments with different zeatin solutions were as follows: a total of 0 μmol / L, 50 μmol / L, 100 μmol / L, 150 μmol / L, 200 μmol / L, and 250 μmol / L concentration gradients were set, and a control group (CK) was set up: the plants were sprayed with ddH2O and placed under normal temperature and light conditions [temperature 28℃ / 18℃, light intensity 300 μmol m -2 s -1 , photoperiod 12 h / 12 ​​h (day / night)].

5. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 1, characterized in that: The pepper variety used is Yangjiao No.

2.

6. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 2, characterized in that: The relevant growth indicators and physical and chemical indicators detected after pepper seedlings were sprayed with different concentrations of zeatin solution are as follows: Growth indicators: plant height, stem diameter, leaf area, root length; Chlorophyll fluorescence parameters: maximum photosynthetic efficiency of photosystem II (Fv / Fm), actual photosynthetic efficiency of photosystem II Y(II), photochemical quenching coefficient qP; Reactive oxygen species: hydrogen peroxide (H2O2) and superoxide anion (O2 - ); Antioxidant enzyme activity: peroxidase (POD), catalase (CAT), superoxide dismutase (SOD).

7. A method for enhancing the stress resistance of pepper seedlings under low temperature and weak light stress as claimed in claim 6, characterized in that: The concentration of the zein solution is preferably 150 μmol / L.

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