Method for improving growth of strawberry offspring plants based on nano CeO2

Abstract

The invention discloses a method for improving growth of strawberry offspring plants based on nano CeO2. The method comprises the following steps: S1, preparing culture soil; s2, strawberry stock plant culture; s3, culturing first-generation strawberry child plants; and S4, culturing second-generation strawberry child plants. According to the method disclosed by the invention, the two generations of strawberry sub-plants are cultured through a stolon propagation method, a relatively high nano CeO2 transport coefficient can be obtained in the two generations of strawberry sub-plants, and the transported nano CeO2 remarkably improves the biomass of the underground part and the overground part of the first generation / second generation of strawberry sub-plants, so that the crop yield is finally improved; according to the method, the proper nanometer CeO2 is only required to be applied to the culture soil of the strawberry mother plant, and does not need to be applied to the culture soil of the strawberry child plant, so that the cost is saved, possible side effects of the nanometer CeO2 can be avoided, and the method has relatively high practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of strawberry cultivation, and specifically to a method for improving the growth of strawberry progeny plants based on nano-CeO2. Background Art

[0002] Research shows that nano-ceria (nano-CeO2) has a certain promoting effect on the growth of plants. Appropriate concentrations of nano-CeO2 particles can promote the germination of some plant seeds. Nano-CeO2 may also participate in regulating the activities of some key enzymes in photosynthesis, making the carbon fixation process of photosynthesis more efficient, helping plants accumulate more photosynthetic products, and promoting plant growth. Nano-CeO2 can affect the absorption and transport of some nutrient elements by plants. For example, it can promote the absorption and utilization of macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients such as iron, zinc, and manganese by plants. This may be because nano-CeO2 changes the microenvironment of plant roots, or affects the activities of ion channels and transport proteins on the root cell membrane, thus facilitating the absorption of nutrient elements and their transportation to the above-ground parts, providing sufficient nutrients for plant growth.

[0003] However, the effect of nano-CeO2 on plant growth is not always positive, and its effect is affected by various factors, such as the particle size, concentration, treatment method of nano-CeO2, and plant species. High concentrations of nano-CeO2 may have a toxic effect on plants and inhibit plant growth. In addition, regarding the growth of plant progeny, the role of nano-CeO2 is still unclear, and the accumulation and migration patterns of nano-CeO2 in plants need to be further studied.

[0004] During the growth process of strawberries, a large number of stolons are produced. Adventitious roots and new seedlings can grow at the internodes of the stolons. After separating these seedlings from the mother plant, they can become independent new plants. Based on this, no one has carried out in-depth research on the mechanism of action of nano-CeO2 in improving the growth of strawberry progeny plants, and at the same time, the step method of nano-CeO2 in improving the growth of strawberry progeny plants needs to be further improved. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for improving the growth of strawberry progeny plants based on nano-CeO2.

[0006] The technical solution of the present invention is as follows:

[0007] A method for improving the growth of strawberry progeny plants based on nano-CeO2, comprising the following steps:

[0008] S1. Cultivation soil preparation: Mix nano-CeO₂ with one portion of soil evenly to obtain the first cultivation soil with a mass concentration of 40 - 60 mg / kg. Take another two portions of soil as the second cultivation soil and the third cultivation soil respectively;

[0009] S2. Strawberry mother plant cultivation: Plant the strawberry mother plant in the first cultivation soil for cultivation, and keep alternating light conditions and dark conditions for cultivation for 28 - 35 days. The rhizome of the strawberry mother plant is 1 - 4 cm, and it has 5 - 8 normally developed compound leaves;

[0010] S3. First-generation strawberry daughter plant cultivation: When the mother plant stolons grow from the strawberry mother plant in S2, conduct in-situ transplanting cultivation. Bury the grown mother plant stolons inside the second cultivation soil, with a burial depth of 1 - 3 cm. When the mother plant stolons continue to grow to 28 - 32 cm, conduct stem guiding and vine pressing, so that an adventitious root on the mother plant stolons penetrates 2 - 5 cm into the second cultivation soil for cultivation, and keep alternating light conditions and dark conditions for cultivation for 28 - 35 days to obtain the first-generation strawberry daughter plants;

[0011] S4. Second-generation strawberry daughter plant cultivation: When the daughter plant stolons grow from the first-generation strawberry daughter plants in S3, conduct in-situ transplanting cultivation. Bury the grown daughter plant stolons inside the third cultivation soil, with a burial depth of 1 - 3 cm. When the daughter plant stolons continue to grow to 28 - 32 cm, conduct stem guiding and vine pressing, so that an adventitious root on the daughter plant stolons penetrates 2 - 5 cm into the third cultivation soil for cultivation, and keep alternating light conditions and dark conditions for cultivation for 28 - 35 days.

[0012] Furthermore, in S1, the particle size of nano-CeO₂ is 25 ± 10 nm, and the first cultivation soil is placed in a dark environment and left to stand and balance for 1 - 2 weeks before use.

[0013] Note: By optimizing the particle size of nano-CeO₂, it can be evenly mixed with the soil.

[0014] Furthermore, in S1, the soil moisture contents of the first cultivation soil, the second cultivation soil, and the third cultivation soil are all adjusted to 60 - 70% of the maximum field water holding capacity.

[0015] Note: By optimizing the soil moisture content of the cultivation soil, it can ensure that the strawberry mother plants and daughter plants have a good growth environment.

[0016] Furthermore, when planting the strawberry mother plants in S2, make the base of the seedling heart flush with the surface of the first cultivation soil, and make the roots spread out flat inside the first cultivation soil. The depth of the first cultivation soil is 20 - 30 cm.

[0017] Note: By optimizing the planting depth of the strawberry mother plants, it can ensure that they have good growth conditions.

[0018] Furthermore, in S2 to S4, during the cultivation of strawberry mother plants, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants, the air humidity is 75 - 85%, the light and dark cycles are maintained at 16 h of light and 8 h of darkness alternately, the light intensity is 600 - 700 Lux, and the cultivation temperature is 20 ± 2°C.

[0019] Note: By optimizing the external conditions such as temperature and humidity during the cultivation of strawberry mother plants, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants, their stable and rapid growth is ensured.

[0020] Furthermore, in S3 and S4, the positions of adventitious roots on the stolons of mother plants and daughter plants are both at ±5 cm in the middle of the stolons of mother plants or daughter plants.

[0021] Note: By optimizing the rooting positions of the stolons of mother plants and daughter plants, the normal growth of strawberry daughter plants is ensured.

[0022] Even further, in S1, 20 - 40 mg / kg of biochar-based soil conditioner is added to the second cultivation soil, and 10 - 20 mg / kg of biochar-based soil conditioner is added to the third cultivation soil.

[0023] Even further, the biochar-based soil conditioner, by weight, includes 30 - 40 parts of straw biochar powder or rice husk biochar powder, 10 - 12 parts of municipal sludge, 3 - 4 parts of coffee grounds, and 1 - 2 parts of microbial inoculant.

[0024] Note: The growth of strawberry daughter plants is assisted and promoted by the biochar-based soil conditioner.

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The method for improving the growth of strawberry progeny plants based on nano-CeO2 of the present invention cultivates two generations of strawberry daughter plants through stolon propagation, and a relatively high nano-CeO2 transport coefficient can be obtained in both generations of strawberry daughter plants. The transported nano-CeO2 significantly increases the biomass of the underground and above-ground parts of the first-generation and second-generation strawberry daughter plants, thereby ultimately increasing the crop yield. It only needs to apply an appropriate amount of nano-CeO2 to the cultivation soil of strawberry mother plants, without the need to apply it to the cultivation soil of strawberry daughter plants, which not only saves costs but also avoids possible side effects of nano-CeO2, and has strong practicality.

[0027] (2) The method for improving the growth of strawberry offspring plants based on nano-CeO2 in the present invention also deeply studies the mechanism of nano-CeO2 acting on strawberry daughter plants. Some key genes that have changed significantly, such as psaK, PHYB, COP1, and HY5, are involved in photosynthesis and circadian rhythm. These genes interact with plant hormone genes such as AUX1, MYC2, and PIF4, providing a basis for nano-CeO2 to promote the growth of strawberry daughter plants. At the same time, nano-CeO2 changes the contents of auxin, cytokinin, jasmonic acid, and salicylic acid in multiple generations of strawberry plants, thereby activating the hormone-induced regulatory network. These findings enhance our understanding of the molecular mechanism of the transmission and growth promotion of nanomaterials in asexually propagated plants and provide potential agricultural development strategies. Description of the Drawings

[0028] Figure 1 shows the changes in the underground biomass of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0029] Figure 2 shows the changes in the above-ground biomass of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0030] Figure 3 shows the change in the photosynthetic parameter F v / F0 value of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0031] Figure 4 shows the change in the photosynthetic parameter P index value of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0032] Figure 5 shows the change in the chlorophyll content of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0033] Figure 6 shows the cumulative Ce concentration of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0034] Figure 7 shows the Ce transfer coefficient TF from the soil to the strawberry mother plant in the experimental examples of the present invention;

[0035] Figure 8 shows the Ce transfer coefficient TF from the strawberry mother plant to the first-generation strawberry daughter plants and from the first-generation strawberry daughter plants to the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0036] Figure 9 shows the effect on the nutrient element content in the leaves of the strawberry mother plant, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants in the soil in the experimental examples of the present invention;

[0037] Figure 10 It is the volcano plot of differentially expressed genes (DEGs) of strawberry mother plants in the experimental examples of the present invention;

[0038] Figure 11 It is the volcano plot of differentially expressed genes (DEGs) of the first-generation strawberry daughter plants in the experimental examples of the present invention;

[0039] Figure 12 It is the volcano plot of differentially expressed genes (DEGs) of the second-generation strawberry daughter plants in the experimental examples of the present invention;

[0040] Figure 13 It is the schematic diagram of photosynthesis in the experimental examples of the present invention;

[0041] Figure 14 It is the protein interaction network of differentially expressed genes (DEGs) in the KEGG pathways related to plant hormones, photosynthesis, and circadian rhythm in the experimental examples of the present invention;

[0042] Figure 15 It is the direct and indirect effects of nano-CeO2, plant hormones, photosynthesis, and circadian rhythm on the biomass of strawberries in the experimental examples of the present invention;

[0043] Figure 16 It is the schematic diagram of the method flow for improving the growth of strawberry progeny plants based on nano-CeO2 in the present invention. Detailed implementation manners

[0044] Example 1

[0045] The method for improving the growth of strawberry progeny plants based on nano-CeO2 includes the following steps:

[0046] S1. Preparation of culture soil: Mix nano-CeO2 with one portion of soil evenly to obtain the first culture soil with a mass concentration of 50 mg / kg. The particle size of nano-CeO2 is 25 ± 10 nm. The first culture soil is placed in a dark environment and left to stand for 1.5 weeks before use. Another two portions of soil are taken as the second culture soil and the third culture soil respectively. The soil water content of the first culture soil, the second culture soil, and the third culture soil is adjusted to 65% of the maximum field water holding capacity;

[0047] S2. Cultivation of strawberry mother plants: Plant the strawberry mother plants in the first culture soil for cultivation. When planting the strawberry mother plants, make the base of the shoot center level with the surface of the first culture soil, and make the roots spread out flat inside the first culture soil. The depth of the first culture soil is 25 cm. Keep alternating cultivation under light conditions and dark conditions for 30 days. The rhizome of the strawberry mother plant is 3 cm and has 6 normally developed compound leaves;

[0048] S3. First-generation strawberry daughter plant cultivation: When the mother plant of the strawberry produces stolons in S2, conduct in-situ transplanting cultivation. Bury the produced mother plant stolons inside the second culture soil, with a burial depth of 2 cm. When the mother plant stolons continue to grow to 30 cm, conduct stem guiding and vine pressing, so that an adventitious root on the mother plant stolons penetrates 3 cm into the second culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 30 days to obtain the first-generation strawberry daughter plants;

[0049] S4. Second-generation strawberry daughter plant cultivation: When the first-generation strawberry daughter plants produce daughter plant stolons in S3, conduct in-situ transplanting cultivation. Bury the produced daughter plant stolons inside the third culture soil, with a burial depth of 2 cm. When the daughter plant stolons continue to grow to 30 cm, conduct stem guiding and vine pressing, so that an adventitious root on the daughter plant stolons penetrates 3 cm into the third culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 30 days;

[0050] In S2 - S4, during the cultivation of the strawberry mother plants, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants, the air humidity is 80% in all cases, and the light and dark are alternated with 16 hours of light and 8 hours of darkness, the light intensity is 650 Lux, and the cultivation temperature is 20°C in all cases;

[0051] In S3 and S4, the positions of the adventitious roots on the mother plant stolons and the daughter plant stolons are both in the middle of the mother plant stolons or the daughter plant stolons.

[0052] Example 2

[0053] The difference between this example and Example 1 lies in: the mixing ratio of nano - CeO₂ and one part of soil in the first culture soil is different.

[0054] Mix nano - CeO₂ and one part of soil evenly to obtain the first culture soil with a mass concentration of 40 mg / kg.

[0055] Example 3

[0056] The difference between this example and Example 1 lies in: the mixing ratio of nano - CeO₂ and one part of soil in the first culture soil is different.

[0057] Mix nano - CeO₂ and one part of soil evenly to obtain the first culture soil with a mass concentration of 45 mg / kg.

[0058] Example 4

[0059] The difference between this example and Example 1 lies in: the mixing ratio of nano - CeO₂ and one part of soil in the first culture soil is different.

[0060] Mix nano - CeO₂ and one part of soil evenly to obtain the first culture soil with a mass concentration of 55 mg / kg.

[0061] Example 5

[0062] The difference between this example and Example 1 lies in that the mixing ratio of nano - CeO₂ and one portion of soil in the first culture soil is different.

[0063] Mix nano - CeO₂ and one portion of soil evenly to obtain the first culture soil with a mass concentration of 60 mg / kg.

[0064] Example 6

[0065] The difference between this example and Example 1 lies in that the specific parameters in S1 are different.

[0066] S1. Preparation of culture soil: The first culture soil is placed in a dark environment and left to stand and balance for 1 week before use. Another two portions of soil are taken as the second culture soil and the third culture soil respectively. The soil moisture contents of the first culture soil, the second culture soil, and the third culture soil are all adjusted to 60% of the field capacity.

[0067] Example 7

[0068] The difference between this example and Example 1 lies in that the specific parameters in S1 are different.

[0069] S1. Preparation of culture soil: The first culture soil is placed in a dark environment and left to stand and balance for 2 weeks before use. Another two portions of soil are taken as the second culture soil and the third culture soil respectively. The soil moisture contents of the first culture soil, the second culture soil, and the third culture soil are all adjusted to 70% of the field capacity.

[0070] Example 8

[0071] The difference between this example and Example 1 lies in that the specific parameters in S2 are different.

[0072] S2. Cultivation of strawberry mother plants: The depth of the first culture soil is 20 cm. Alternate cultivation under light conditions and dark conditions is carried out for 28 days. The rootstock of the strawberry mother plant is 1 cm, and it has 5 normally developed compound leaves.

[0073] Example 9

[0074] The difference between this example and Example 1 lies in that the specific parameters in S2 are different.

[0075] S2. Cultivation of strawberry mother plants: The depth of the first culture soil is 30 cm. Alternate cultivation under light conditions and dark conditions is carried out for 35 days. The rootstock of the strawberry mother plant is 4 cm, and it has 8 normally developed compound leaves.

[0076] Example 10

[0077] The difference between this example and Example 1 lies in that the specific parameters in S3 are different.

[0078] S3. Cultivation of the first-generation strawberry daughter plants: When the mother plant of the strawberry produces mother plant stolons in S2, carry out in-situ transplanting cultivation. Bury the produced mother plant stolons inside the second culture soil, with a burial depth of 1 cm. When the mother plant stolons continue to grow to 28 cm, carry out stem guiding and vine pressing, so that an adventitious root on the mother plant stolons penetrates 2 cm into the second culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 28 days to obtain the first-generation strawberry daughter plants.

[0079] Example 11

[0080] The difference between this example and Example 1 lies in: different specific parameters in S3.

[0081] S3. Cultivation of the first-generation strawberry daughter plants: When the mother plant of the strawberry produces mother plant stolons in S2, carry out in-situ transplanting cultivation. Bury the produced mother plant stolons inside the second culture soil, with a burial depth of 3 cm. When the mother plant stolons continue to grow to 32 cm, carry out stem guiding and vine pressing, so that an adventitious root on the mother plant stolons penetrates 5 cm into the second culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 35 days to obtain the first-generation strawberry daughter plants.

[0082] Example 12

[0083] The difference between this example and Example 1 lies in: different specific parameters in S4.

[0084] S4. Cultivation of the second-generation strawberry daughter plants: When the first-generation strawberry daughter plants in S3 produce daughter plant stolons, carry out in-situ transplanting cultivation. Bury the produced daughter plant stolons inside the third culture soil, with a burial depth of 1 cm. When the daughter plant stolons continue to grow to 28 cm, carry out stem guiding and vine pressing, so that an adventitious root on the daughter plant stolons penetrates 2 cm into the third culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 28 days.

[0085] Example 13

[0086] The difference between this example and Example 1 lies in: different specific parameters in S4.

[0087] S4. Cultivation of the second-generation strawberry daughter plants: When the first-generation strawberry daughter plants in S3 produce daughter plant stolons, carry out in-situ transplanting cultivation. Bury the produced daughter plant stolons inside the third culture soil, with a burial depth of 3 cm. When the daughter plant stolons continue to grow to 32 cm, carry out stem guiding and vine pressing, so that an adventitious root on the daughter plant stolons penetrates 5 cm into the third culture soil for cultivation, and maintain alternating cultivation of light conditions and dark conditions for 35 days.

[0088] Example 14

[0089] The difference between this example and Example 1 lies in:

[0090] In S2 to S4, during the cultivation of strawberry mother plants, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants, the air humidity is 75% in all cases. The light and dark periods are alternated with 16 hours of light and 8 hours of darkness, the light intensity is 600 Lux, and the cultivation temperature is 18°C in all cases.

[0091] In S3 and S4, the position of adventitious roots on the mother plant stolons and daughter plant stolons is at the middle - 5 cm of the mother plant stolons or daughter plant stolons.

[0092] Example 15

[0093] The difference between this example and Example 1 is as follows:

[0094] In S2 to S4, during the cultivation of strawberry mother plants, the first-generation strawberry daughter plants, and the second-generation strawberry daughter plants, the air humidity is 85% in all cases. The light and dark periods are alternated with 16 hours of light and 8 hours of darkness, the light intensity is 700 Lux, and the cultivation temperature is 22°C in all cases.

[0095] In S3 and S4, the position of adventitious roots on the mother plant stolons and daughter plant stolons is at the middle + 5 cm of the mother plant stolons or daughter plant stolons.

[0096] Example 16

[0097] The difference between this example and Example 1 is as follows:

[0098] In S1, 30 mg / kg of biochar-based soil conditioner is added to the second cultivation soil, and 15 mg / kg of biochar-based soil conditioner is added to the third cultivation soil. The biochar-based soil conditioner, by weight, includes 35 parts of straw biochar powder or rice husk biochar powder, 11 parts of municipal sludge, 3.5 parts of coffee grounds, and 1.5 parts of microbial inoculant. The microbial inoculant is Bacillus subtilis, and the effective viable count > 0.5 billion / mL.

[0099] Example 17

[0100] The difference between this example and Example 16 is as follows:

[0101] In S1, 20 mg / kg of biochar-based soil conditioner is added to the second cultivation soil, and 10 mg / kg of biochar-based soil conditioner is added to the third cultivation soil. The biochar-based soil conditioner, by weight, includes 30 parts of straw biochar powder or rice husk biochar powder, 10 parts of municipal sludge, 3 parts of coffee grounds, and 1 part of microbial inoculant.

[0102] Example 18

[0103] The difference between this example and Example 16 is as follows:

[0104] In S1, 40 mg / kg of biochar-based soil conditioner was added to the second culture soil, and 20 mg / kg of biochar-based soil conditioner was added to the third culture soil. The biochar-based soil conditioner, by weight, includes 40 parts of straw biochar powder or rice husk biochar powder, 12 parts of municipal sludge, 4 parts of coffee grounds, and 2 parts of microbial inoculum.

[0105] Experimental Example

[0106] The nano-CeO2 (purity > 99.95%) used in this experiment was purchased from Sigma-Aldrich. Its particle size and morphology were characterized by transmission electron microscopy (Tecani G2 Spirit TWIN, FEI, Netherlands), with an average particle size of 24.6 ± 10.2 nm. The natural soil was collected from a farmland soil with a texture of sandy loam, and the contents of clay, silt, and sand were 3.82%, 62.83%, and 33.35% respectively. The soil pH-H2O, available phosphorus, available potassium, organic matter, and Ce concentration were 6.68, 9.77 mg / kg, 163 mg / kg, 44.4 g / kg, and 6.87 mg / kg respectively. The soil samples were air-dried and passed through a 2 mm sieve and stored for pot experiments.

[0107] I. After culturing according to the method in Example 1, the culture results were analyzed. The results showed that nano-CeO2 significantly increased the fresh weights of the underground and aboveground parts of the first-generation strawberry daughter plants (increased by 139% and 54% respectively) and the fresh weights of the underground and aboveground parts of the second-generation strawberry daughter plants (increased by 74% and 75% respectively) ( Figure 1 and 2 );

[0108] In addition, the photosynthetic parameters (F v / F0, P index) and chlorophyll content of multi-generation plants treated with nano-CeO2 were 23%-24%, 82%-106%, and 10%-27% higher than those of the control group respectively ( Figures 3 to 5 ). Previous studies have shown that low-concentration Ce 3+ can enter chloroplasts and bind to chlorophyll, promoting chlorophyll synthesis and photosynthetic rate. The enhanced photosynthesis at the leaf level can directly promote plant biomass accumulation, and these findings highlight the importance of nano-CeO2 in improving plant growth and development.

[0109] II. Under the exposure of strawberry mother plants, nano-CeO2 was absorbed by the roots of strawberry mother plants and transported to the leaf and stolon tissues ( Figures 6 to 7 ). Specifically, the Ce accumulation amounts in the roots, leaves, and stolons of strawberry mother plants exposed to 50 mg / kg nano-CeO2 reached 1.86×10 3μg / kg, 36.1 μg / kg, and 366 μg / kg. Studies have shown that after root exposure, nano-CeO2 is mainly enriched in the roots, and only about 1.00% is transported to the shoots. Similarly, the distribution of nano-CeO2 in strawberry mother plants is roots > stolons > leaves. The transport of Ce from underground to aboveground tissues occurs through the xylem, and the decrease in Ce concentration in the shoots indicates the existence of radial movement. Ce accumulated in the roots may be stored in the cortical tissues due to this movement, thus preventing Ce from entering the leaves. In addition, the translocation factors of Ce from roots to leaves and stolons in strawberry mother plants are 0.0194 and 0.197, respectively.

[0110] After nanoparticles accumulate in strawberry mother plants, they can enter daughter plants through the connected stolons. The distribution of Ce in the first and second strawberry daughter plant tissues is consistent with that in strawberry mother plants: roots (1.13×10 3 and 1.58×10 3 μg / kg) > stolons (273 and 234 μg / kg) > leaves (6.99 and 25.3 μg / kg) ( Figure 6 ). This result is consistent with the result of a high proportion of Ce in the roots of multi-generation ramets. The translocation factors of Ce from stolons to daughter leaves, stolons, and roots are: for strawberry mother plants - the first generation of strawberry daughter plants, 0.0197 < 0.755 < 3.16; for the first generation of strawberry daughter plants - the second generation of strawberry daughter plants, 0.0934 < 0.856 < 5.80 ( Figure 8 ). This indicates that the sharing of Ce among multi-generation ramets does not decrease with the increase of generations. The interaction between nano-CeO2 and plant metabolites (such as the formation, aggregation, and dissolution of the biological corona on the nanoparticle surface) may affect its plant behavior and accumulation.

[0111] In addition to Ce analysis, it was also found that nano-CeO2 reprogrammed the nutrient element profiles in plants ( Figure 9 ). Notably, nano-CeO2 significantly reduced the levels of micronutrient elements in the first generation of strawberry daughter plants. Nano-CeO2 may compete with or displace elements such as Fe, thus affecting the absorption of certain nutrients by plants and influencing plant growth and development by altering the activities of element-regulating enzymes.

[0112] III. Global transcriptome analysis

[0113] Transcriptome analysis further revealed the molecular starting events of plant physiological and biochemical development. After strawberry mother plants were exposed to nano-CeO2, significant differences were observed in the leaf transcript profiles of multi-generation plants (strawberry mother plants, the first generation of strawberry daughter plants, and the second generation of strawberry daughter plants). Principal component analysis (PCA) showed that the gene expression patterns of the nano-CeO2 treatment were significantly distinguishable from those of the control group. With |log2(fold change)| > 2 and P adjWith <0.01 as the standard, 3694 (2333 upregulated and 1361 downregulated), 19101 (11395 upregulated and 7706 downregulated), and 3882 (2475 upregulated and 1407 downregulated) differentially expressed genes (DEGs) were identified in strawberry mother plants, first-generation strawberry daughter plants, and second-generation strawberry daughter plants, respectively, and shown by volcano plots ( Figures 10 to 12 ).

[0114] Specifically, nano-CeO2 led to more upregulated than downregulated DEGs, indicating its positive effect on strawberry transcriptional activity. In terms of the number of DEGs, the first-generation strawberry daughter plants were more sensitive to nano-CeO2 than other plants. The phenomenon of adaptive transgenerational memory in multiple generations of plants has been widely reported. This result may be related to the positive regulation of transgenerational memory on the response of offspring plants to nano-CeO2.

[0115] In addition, studies have shown that the resource sharing connecting ramets is affected by the ramet development stage. Compared with the first-generation strawberry daughter plants, the second-generation strawberry daughter plants with lower biomass are in the early stage of ramet development and have lower nutrient requirements, which may lead to lower transcriptional activity.

[0116] These DEGs were matched to their potential biological functions through the KEGG database. The significantly activated biological functions of nano-CeO2 were mainly related to plant hormone signal transduction, photosynthesis, and circadian rhythm, and the specific analysis is as follows.

[0117] Plant hormone signal transduction

[0118] Plant hormones play a central role in cell-to-cell crosstalk and signal transduction. After the strawberry mother plants were exposed to nano-CeO2, the transcript effect level index (TELI) values of the "plant hormone signal transduction", "cysteine and methionine metabolism", and "phenylalanine, tyrosine, and tryptophan biosynthesis" pathways in the leaves of the first-generation strawberry daughter plants increased significantly, indicating that nano-CeO2 caused hormonal transcriptional changes in strawberry mother plants and offspring plants.

[0119] Consistent with the results of this study, previous research reported that exposing roots to 70 mg / kg CeO2 nanoparticles significantly affected the metabolic pathways of phytohormones such as auxin and jasmonic acid in pakchoi. Notably, after the strawberry mother plants were exposed to nano-CeO2, the expression of genes related to the above pathways in plants (such as cysE, aroF, AOC, AUX1, JAZ, and MYC2) was significantly regulated. These genes are mainly involved in the biosynthesis, distribution, and signal transduction of hormones. Among them, the protein encoded by the aroF gene catalyzes the formation of 3-dehydroquinate from D-erythrose-4-phosphate, which is a step in the biosynthesis of auxin and salicylic acid. AOC is a key enzyme in the biosynthesis of jasmonic acid and can produce the biosynthetic precursor of jasmonic acid. The AUX1 gene is the main auxin influx carrier and mediates the transport of auxin between plant tissues. The JAZ and MYC2 genes can also regulate processes related to plant development and growth. Changes in the expression of these genes may affect the content of phytohormones in tissues.

[0120] Therefore, the hormone content in plant leaves was further detected. The data showed that nano-CeO2 reprogrammed the hormone profiles of strawberry mother plants, first-generation strawberry daughter plants, and second-generation strawberry daughter plants. Specifically, the contents of auxin, salicylic acid, jasmonic acid, and cytokinin in the strawberry mother plants / first-generation strawberry daughter plants / second-generation strawberry daughter plants in the treatment group were 0.321 / 0.705 / 0.451, 4.16 / 2.31 / 0.855, 2.47 / 1.45 / 0.897, and 1.04 / 1.11 / 1.12 times that of the control group, respectively. These hormones are involved in photosynthesis-related processes such as stomatal and chloroplast development and further regulate photosynthetic activity. For example, a decrease in auxin may induce the formation of stomatal clusters and promote photosynthesis. In addition, high levels of cytokinin positively regulate the development of chloroplast structure and function. The differential changes among multiple generations of plants indicate that adaptive transgenerational memory has hormone and ramet development dependence and is worthy of further study.

[0121] Plant photosynthesis

[0122] Photosynthesis is the process by which plants convert CO2 into organic matter ( Figure 13 ), maintaining plant growth. The TELI values of photosynthesis in the strawberry mother plants / first-generation strawberry daughter plants / second-generation strawberry daughter plants in the treatment group increased significantly, being 9.58 times, 2.52×10 3 times, and 8.49 times that of the control group, respectively, indicating that the application of nano-CeO2 to strawberry mother plants positively regulates the photosynthetic potential of plants.

[0123] This view is consistent with the findings of some researchers that low concentrations of CeO2 nanoparticles (0 - 100 mg / kg) can stimulate the photosynthetic process of plants. Notably, heatmap analysis showed that DEGs related to photosynthesis were mainly divided into five categories: photosystem II (PSII), cytochrome b6 / f complex, electron transport, photosystem I (PSI), and ATP synthase. Specifically, nano - CeO2 down - regulated the expression of some DEGs related to PSII and PSI processes in the first - generation strawberry daughter plants, while up - regulating the expression of these genes in strawberry mother plants and second - generation strawberry daughter plants. The PSII process can capture electrons from H2O and provide electrons for the production of organic matter (i.e., the PSI process). This transcriptome data is inconsistent with the results of plant photosynthetic activity( Figure 1 ), which may be due to the fact that photosynthesis is affected by both transcriptional and post - transcriptional regulation and enzyme activity.

[0124] Plant circadian rhythm

[0125] The circadian rhythm is an internal timing mechanism in plants that can temporally regulate their metabolic, physiological, and behavioral characteristics. The TELI values of plants in each generation in the nano - CeO2 treatment group were significantly higher than those in the control group (control group: 0.103 - 0.793; nano - CeO2 group: 3.52 - 9.92), indicating that nano - CeO2 has a positive regulatory effect on the circadian rhythm.

[0126] This result is consistent with previous studies that molecular changes related to the circadian rhythm occur in plants and animals after exposure to metal - based nanoparticles and metals. In addition, nano - CeO2 reprogrammed the expression profiles of some DEGs related to the circadian system (including input pathways, central oscillator, and output pathways). Notably, the expression of two signature photoreceptor genes, PHYA and PHYB, in the input pathway, changed significantly in plants after nano - CeO2 exposure. Studies have shown that photoreceptors in the input pathway can mediate plant growth and development by integrating light signals and the core oscillator. For example, the expression trends of genes related to the output pathway (such as ELF3, GI, CO, COP, and HY5) were consistent with those of genes related to the input pathway (such as PHYA, PHYB, and CRY). Previous studies have confirmed the regulatory roles of CO and HY5 genes in flowering and photosynthesis. Therefore, the circadian rhythm changes caused by nano - CeO2 may regulate the photosynthetic process of plants.

[0127] Molecular mechanism of strawberry daughter plants' response to nano - CeO2 transport

[0128] By constructing a protein-protein interaction network of 136 key DEGs (including 78 nodes and 501 interactions, with an average node degree of 12.8 and a clustering coefficient of 0.692), it was found that PSI-related genes (psaB, psaK), hormone signaling genes (AUX1, PIF4, MYC2), and circadian clock genes (PHYB, PHYA, COP1, GI, HY5) constitute the core hub genes( Figure 14 ). Structural equation modeling (SEM) showed that nano-CeO2 indirectly regulates the biomass of strawberry daughter plants through the circadian rhythm (total standardized effect value: -0.379) and the hormone signaling network (0.962), explaining 52% of the growth variation( Figure 15 ). Among them, the interaction between the photoreceptor PHYB and the auxin transporter AUX1 and the transcription factor PIF4 promotes plant growth by regulating cell elongation and auxin signal transduction.

Claims

1. A method for improving the growth of strawberry progeny plants based on nano-CeO2, characterized in that, It includes the following steps: S1. Cultivated soil preparation: Mix nano - CeO₂ with one portion of soil evenly to obtain the first cultivated soil with a mass concentration of 40 - 60 mg / kg, and take another two portions of soil as the second cultivated soil and the third cultivated soil respectively; S2. Strawberry mother plant cultivation: Plant the strawberry mother plant in the first cultivated soil for cultivation, keep alternating between light conditions and dark conditions for 28 - 35 days. The rhizome of the strawberry mother plant is 1 - 4 cm, and it has 5 - 8 normally developed compound leaves; S3. First - generation strawberry daughter plant cultivation: When the mother plant stolons grow from the strawberry mother plant in S2, carry out in - situ transplantation cultivation. The mother plant stolons drawn out are buried inside the second cultivated soil, and the burial depth is 1 - 3 cm. When the mother plant stolons continue to grow to 28 - 32 cm, carry out stem guiding and vine pressing, so that an adventitious root on the mother plant stolons penetrates 2 - 5 cm into the second cultivated soil for cultivation, keep alternating between light conditions and dark conditions for 28 - 35 days to obtain the first - generation strawberry daughter plants; S4. Second - generation strawberry daughter plant cultivation: When the daughter plant stolons grow from the first - generation strawberry daughter plants in S3, carry out in - situ transplantation cultivation. The daughter plant stolons drawn out are buried inside the third cultivated soil, and the burial depth is 1 - 3 cm. When the daughter plant stolons continue to grow to 28 - 32 cm, carry out stem guiding and vine pressing, so that an adventitious root on the daughter plant stolons penetrates 2 - 5 cm into the third cultivated soil for cultivation, keep alternating between light conditions and dark conditions for 28 - 35 days.

2. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, characterized in that, In S1, the particle size of nano - CeO₂ is 25 ± 10 nm, and the first cultivated soil is placed in a dark environment and left to stand and balance for 1 - 2 weeks before use.

3. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, characterized in that, In S1, the soil moisture content of the first cultivated soil, the second cultivated soil and the third cultivated soil is adjusted to 60 - 70% of the maximum field water - holding capacity.

4. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, characterized in that, When planting the strawberry mother plant in S2, make the base of the seedling heart flush with the surface of the first cultivated soil, and make the roots spread out flat inside the first cultivated soil. The depth of the first cultivated soil is 20 - 30 cm.

5. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, characterized in that, In S2 - S4, when cultivating the strawberry mother plant, the first - generation strawberry daughter plants and the second - generation strawberry daughter plants, the air humidity is 75 - 85% in all cases, keep alternating between 16 h of light and 8 h of darkness, the light intensity is 600 - 700 Lux, and the cultivation temperature is 20 ± 2 °C in all cases.

6. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, wherein In S3 and S4, the position of the adventitious roots on the mother plant stolons and the daughter plant stolons is located at ± 5 cm in the middle of the mother plant stolons or the daughter plant stolons.

7. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 1, characterized in that In S1, 20 - 40 mg / kg of biochar - based soil conditioner is added to the second cultivated soil, and 10 - 20 mg / kg of biochar - based soil conditioner is added to the third cultivated soil.

8. The method for improving the growth of strawberry progeny plants based on nano-CeO2 according to claim 7, characterized in that, The biochar - based soil conditioner, by weight, includes 30 - 40 parts of straw biochar powder or rice husk biochar powder, 10 - 12 parts of municipal sludge, 3 - 4 parts of coffee grounds, and 1 - 2 parts of microbial inoculant.

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