Subtropical region lotus lamp cutting seedling raising method

Abstract

The application discloses a cuttage seedling raising method for Lotus Lamp in subtropical regions and belongs to the technical field of plant cuttage breeding. The cuttage seedling raising method for Lotus Lamp in subtropical regions comprises the following steps: taking half-lignified branches with a width of more than 1 cm as cuttings, sequentially performing disinfection and hormone solution soaking on the base of the cuttings, and then inserting the cuttings into a disinfected substrate; the hormone solution is prepared by mixing IAA and IBA at a volume ratio of 1:1, and then adding 0.5 mL of 1.8% sodium nitrophenol solution per liter of the hormone solution; and the substrate is composed of peat, coconut dregs and perlite at a volume ratio of 4:1:1. Through the method, the rooting rate of the cuttings can reach 97.78% on the 45th day, and the application provides a new method for cuttage seedling raising of Lotus Lamp in subtropical regions and provides a technical reference for local industry development.

Description

Technical Field

[0001] This invention relates to the field of plant propagation by cuttings, and in particular to a method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions. Background Technology

[0002] Lotus Lantern, scientifically known as *Pterocarya stenoptera* (also called Pterocarya stenoptera), is a type of plant. Medinilla magnifica *Morchella asiatica*, a species of evergreen shrub belonging to the genus *Morchella* in the family Melastomataceae, is native to the tropical rainforests of Malaysia and other regions. The genus comprises over 300 wild species, among which *Morchella asiatica* has been developed into a high-end potted ornamental plant. *Morchella asiatica* has a flowering period of 3-6 months, with large, drooping panicles covered in pink or rose-red bracts. The unique shape of the inflorescence resembles a lotus lantern. The leaves are ovate to elliptical, dark green, and glossy, making it suitable for display in hotels, shopping mall windows, halls, and villa rooms. Currently, light pink, dark pink, and ruby ​​red varieties of *Morchella asiatica* are commonly sold in China. In recent years, *Morchella asiatica* has gained market favor due to its excellent ornamental value and long flowering period, leading to increasing demand. Therefore, there is an urgent need to establish an efficient breeding technology system.

[0003] Conventional propagation methods for *Nelumbo nucifera* (also known as lantern plant) primarily include seed propagation, tissue culture, and cutting propagation. However, in non-tropical regions, the fruits of *Nelumbo nucifera* often develop poorly, making seed production difficult, and sexual reproduction is prone to phenotypic variation. While tissue culture is feasible, it is costly, technically demanding, and time-consuming. In contrast, cutting propagation offers advantages such as rapid seedling formation, stable genetic traits, and ease of operation, making it the primary method for large-scale propagation of *Nelumbo nucifera*. Cutting propagation involves inserting vegetative organs such as roots, stems, and leaves of the plant into a loose, moist substrate, utilizing its regenerative capacity to encourage rooting and branching into new plants.

[0004] Currently, large-scale propagation and cultivation of *Nelumbo nucifera* (a type of lantern flower) through cuttings in China is mainly concentrated in northern provinces such as Shandong and Tianjin. This is typically done in controlled greenhouses equipped with heating, cooling, and external shading systems, resulting in high initial equipment investment, ongoing maintenance costs, and stringent management techniques. my country's subtropical regions are typical East Asian monsoon climate zones, characterized by simultaneous rainfall and heat, with an average annual temperature of 16-20℃ and annual precipitation of 800-2000 mm. Therefore, considering the climatic characteristics of subtropical regions and supplementing them with appropriate cultivation and protection facilities, research on *Nelumbo nucifera* cutting propagation techniques should be conducted to develop techniques suitable for subtropical areas, providing technical support for the local industry's development. Summary of the Invention

[0005] The purpose of this invention is to provide a method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions, in order to solve the problems existing in the prior art. With the method provided by this invention, the rooting rate of cuttings can reach 97.78% on the 45th day.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions, comprising the following steps: Semi-lignified branches with a width >1cm were used as cuttings. The base of the cuttings was disinfected and soaked in hormone solution in sequence, and then inserted into the disinfected substrate to obtain cuttings. The hormone solution is prepared by mixing IAA and IBA at a volume ratio of 1:1, and adding 0.5 mL of 1.8% sodium nitrophenolate solution per liter of hormone solution. The matrix consists of peat, coconut coir, and perlite in a volume ratio of 4:1:1.

[0007] Optionally, the disinfection involves immersing the base of the cutting in an 800-fold solution of 50% carbendazim wettable powder for 15 minutes.

[0008] Optionally, in the hormone solution, the concentrations of both the IAA and the IBA are 100 mg / L.

[0009] Optionally, the soaking time in the hormone solution is 15-30 minutes.

[0010] Preferably, the soaking time in the hormone solution is 30 minutes.

[0011] Optionally, after the cuttings are inserted into the sterilized substrate, the step of compacting the substrate around the cuttings is also included.

[0012] Optionally, the climate of the location where the *Nelumbo nucifera* cuttings are propagated is a subtropical marine monsoon climate.

[0013] Optionally, the varieties of the Lotus Lantern include deep pink, ruby ​​red, and light pink.

[0014] Optionally, the method also includes the step of spraying the cuttings with a compound bacterial solution; The compound bacterial solution is composed of Bacillus subtilis ( Bacillus subtilis ), Bacillus licheniformis ( Bacillus licheniformis ) and gelatinous spore-forming bacteria ( Bacillus subtilis The compound bacteria were obtained by mixing them evenly in a mass ratio of 3:1:1, letting them stand for 1 hour, and then adding 15L of water, 0.5 kg of brown sugar and 10g of potassium dihydrogen phosphate. The mixture was then sealed and fermented for 3-5 days. The effective viable count of the compound bacteria is not less than 20 billion / g.

[0015] Optionally, the compound bacterial solution can be diluted 1000 times before spraying.

[0016] The present invention discloses the following technical effects: This invention employs an orthogonal experimental design. The results show that hormone concentration has a highly significant impact on the propagation effect of *Nelumbo nucifera* cuttings, while variety significantly affects the survival and rooting rates. Substrate and hormone treatment time have minimal impact on the propagation effect. A hormone concentration of 100 mg / L IAA + 100 mg / L IBA showed the best effect on *Nelumbo nucifera* cuttings, significantly promoting adventitious root formation and growth; excessively high hormone concentrations, however, inhibited rooting. Cuttings of the *Nelumbo nucifera* 'Ruby Red' variety rooted more easily and faster than the other two varieties, achieving a rooting rate of 97.78% on the 45th day at this hormone concentration (treatment 2). Considering all factors, in the production of *Nelumbo nucifera* cuttings, it is recommended that cuttings of these three varieties be soaked in a hormone combination of 100 mg / L IAA + 100 mg / L IBA for 15-30 minutes, with a propagation substrate of peat moss + coconut coir (2:1) or a mixture of peat moss + coconut coir + perlite (4:1:1). Meanwhile, the compound bacterial treatment with Bacillus subtilis as the main component can significantly promote the root growth of 'Deep Pink' 'Balan Lantern', promote early root emergence, and improve the rooting rate. The effect of compound bacterial treatment on the root growth of 'Deep Pink' 'Balan Lantern' has a concentration effect, with a ratio of 1:1000 showing better results. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The varieties of 'deep pink' (1), 'ruby red' (2), and 'light pink' (3) are potted lotus flowers; Figure 2 The effect of different treatments on the survival rate of *Monophyllum indicum* cuttings; A: 45-day survival rate, B: 90-day survival rate; Figure 3 The effect of different treatments on the rooting rate of *Mediterranean orientalis* cuttings; Figure 4 The effects of different treatments on the root growth of *Morchella oleracea* cuttings; A: Number of roots with a length greater than 5 cm at 45 days; B: Root width at 45 days; Figure 5 The root growth status of *Morchella asiatica* cuttings under different treatments after 45 days; AI represents treatments 1-9 respectively. Figure 6 The effect of compound microbial treatment on the root growth of *Nelumbo nucifera* cuttings after 35 days was investigated. A: Treatment with a 1:500 compound microbial solution; B: Treatment with a 1:1000 compound microbial solution; C: Treatment without compound microbial solution. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] The experimental site for this invention was selected in Zhangzhou, Fujian Province, a region with a subtropical maritime monsoon climate, bordered by mountains to the northwest and the sea to the southeast; winters are mild, summers are long and hot with consistently high humidity. Currently, research on the propagation of *Nelumbo nucifera* (a type of lantern tree) by cuttings is limited, with differing opinions on the selection and application of plant growth regulators and substrates in cuttings, and a lack of research on the influence of variety on *Nelumbo nucifera* cuttings. This invention integrates technologies from aspects such as mother tree selection, nursery preparation, scion collection and treatment, cutting and management, and seedling management, with a particular focus on in-depth exploration of variety and substrate selection, scion treatment techniques, and post-cutting management techniques.

[0025] Example 1 1. Materials and Methods 1.1 Materials Choose from three flower varieties: 'light pink', 'dark pink', and 'ruby red'. Figure 1 The potted plants were preserved in the improved seed base (botanical garden) of Minnan Normal University in Zhangzhou, Fujian Province in 2019. Cutting propagation experiments were conducted in 2023-2024.

[0026] 1.2 Methods 1.2.1 Nursery Site Selection and Preparation Choose a flat, well-drained, and easily irrigated bare plot of land. Construct a simple greenhouse (the greenhouse roof is covered with a movable shade net and a fixed PO plastic film, 3.0m high, 18m long, and 15m wide; one side of the greenhouse can be fixed to a wall, while the other three sides are movable film curtains). Clear and level the ground beforehand, creating seedbeds 10-15m long, 120cm wide, and 10-15cm high. Spread a 5-10cm layer of fine sand (0.6-1.5cm particle size) or red soil on the seedbeds. Simultaneously, construct small arched sheds on the seedbeds, 40-50cm high and 70-110cm wide, covered with translucent PE film. The shed supports should use elastic solid fiberglass poles. Leave a 20-30cm aisle between the seedbeds. One week before cuttings, spray the seedbeds with a 1000-fold dilution of 50% carbendazim wettable powder for sterilization.

[0027] 1.2.2 Matrix Selection and Treatment Use peat moss, coconut coir, and perlite in a specific ratio as the cutting substrate. The peat moss should be 1-10 mm thick, the coconut coir 2-5 mm thick, and the perlite 2-4 mm in diameter. One week in advance, spread out the peat moss and coconut coir separately, spray them with a 100-fold diluted 40% formalin solution, cover them with a plastic film and seal for 48 hours. Then, uncover the film and leave them for 72 hours before bagging them to allow the disinfectant odor to dissipate. One day before cutting, mix the substrates separately in a specific ratio (see Table 1), stir well, and then spray with water until water droplets can be squeezed out between the fingers. Fill the substrate with a planting bag (10 cm × 12 cm).

[0028] 1.2.3 Cutting time Choose to take cuttings from April to June or from September to November, avoiding the hot summer months; cuttings can also be taken from November to March, but the rooting time is longer.

[0029] 1.2.4 Treatment and propagation of cuttings Preparation of mixed hormone solution: IAA and IBA (purity 99%) purchased from Shanghai Guoyao were prepared into 1000mg / L stock solutions respectively; IAA and IBA were mixed at a volume ratio of 1:1, and 0.5mL of 1.8% sodium nitrophenolate solution was added to each L of mixed hormone solution.

[0030] Using robust, disease-free potted *Nelumbo nucifera* plants (with 3-4 layers of leaves) provided by the seed base greenhouse of Minnan Normal University, with a plant height of 50-70cm and a crown width of (30-40cm) × (30-40cm), as the mother plants for cuttings, semi-lignified branches with a width >1cm were selected. The cuttings were 5-10cm long, with one pair of leaves. The upper cut was made flat (1-2cm from the opposite leaf), and the lower cut was made obliquely. The cuts of the cuttings should be smooth. After pruning, the cuttings were bundled into groups of 20 according to their type. The base of the cuttings was soaked in an 800-fold dilution of 50% carbendazim wettable powder for 15 minutes (for disinfection). After being taken out and dried for 10-15 minutes, they were then soaked in a mixed hormone solution (see Table 1). After being treated with different concentrations of hormones for different times, they were taken out and dried for 10-15 minutes before being inserted into the corresponding treated substrate. The base of the cuttings was inserted into the substrate about 5cm, and the substrate around the cuttings was compacted. Cuttings were taken in the morning. In Table 1, the concentrations of hormones (IAA+IBA) A, 1, 2, and 3 represent 100, 200, and 300 mg / L, respectively; the treatment times B, 1, 2, and 3 represent 15, 30, and 60 min, respectively; the substrates C, 1, 2, and 3 represent whole peat, peat:coco coir:perlite = 4:1:1 (volume ratio), and peat:coco coir = 2:1 (volume ratio), respectively; and the varieties D, 1, 2, and 3 represent 'deep pink', 'ruby red', and 'light pink', respectively.

[0031] Table 1. Propagation Techniques of *Nelumbo nucifera* by Cuttings L9(3) 4 Orthogonal experimental combination design table 1.2.3 Management of Cuttings After cutting, place the cuttings in 2.8-inch cups with 15 holes (44.2cm × 26.8cm) with the leaves facing the same direction. Then, move them into a self-made small arched greenhouse. Arrange the cuttings neatly in different areas according to their different treatments and manage them appropriately: cover the small arched greenhouse with plastic film, press the bottom firmly to prevent air leakage, and maintain the relative humidity inside the small arched greenhouse above 80%. Water the bottom sand of the seedbed as needed. Ten days before cutting, cover the small arched greenhouse with a 45% shading net to maintain the temperature at 20~30℃. During April-June and September-November, if there is high temperature and strong sunlight and the temperature inside the greenhouse exceeds 30℃, the shading net should be opened. Install a spray pipe along the long side of each seedbed at a height of 3m above the ground, with a spray head installed every 1.2m to spray and cool the soil. At the same time, roll up the curtains on the left and right sides of the greenhouse for ventilation. Continuously monitor the condition of the cuttings inside the greenhouse. If any rotten branches are found, remove them along with the substrate.

[0032] During the management of cuttings, in order to promote rooting and strong seedling growth of *Nelumbo nucifera* 'Variegata' and shorten the rooting time for earlier transplanting, based on the results of orthogonal experiments, using 'Shenfen' *Nelumbo nucifera* 'Variegata' as the experimental material, a cutting treatment method of treatment 5 was adopted. When the cuttings developed callus tissue (approximately 10 days after cutting), the cuttings were sprayed with a compound bacterial solution of different concentrations (1:500, i.e., diluted 500 times; 1:1000, i.e., diluted 1000 times). (This compound bacterial solution is composed of *Bacillus subtilis*...) Bacillus subtilis CGMCC1.3358, Bacillus licheniformis ( Bacillus licheniformis CGMCC 1.813 and Bacillus jellyoidus ( Bacillus subtilis CGMCC 1.231 was mixed evenly at a mass ratio of 3:1:1 and allowed to stand for 1 hour (effective viable bacteria count not less than 20 billion / g). Then, 15L of water, 0.5 kg of brown sugar, and 10g of potassium dihydrogen phosphate were added, stirred evenly, and fermented at room temperature in a sealed container for 3-5 days (stirring once every 12 hours during fermentation). Rooting was observed and counted at 35 days. Each treatment had 25 plants, replicated 3 times, for a total of 75 plants per treatment.

[0033] 1.2.4 Index Measurement In the orthogonal experiment, on day 45 of the cutting culture, the survival rate (number of surviving plants / total number of cuttings × 100%) and rooting rate (number of rooted plants / total number of cuttings × 100%) of each treatment were observed and statistically analyzed. For each treatment, 5 plants were randomly sampled from each replicate to measure the number of roots longer than 5 cm (the number of roots longer than 5 cm among the roots grown from each cutting) and root width (the width of the horizontally extended root system of the cutting). On day 90 of the cutting culture, the survival rate of each treatment was observed and statistically analyzed again. Each treatment had 25 plants, replicated 3 times, for a total of 75 plants per treatment.

[0034] 1.2.5 Data Processing and Statistical Analysis Excel software was used to organize and calculate the experimental data, and SPSS software was used to perform range analysis, variance analysis, and LSD multiple comparisons on the experimental data.

[0035] 2 Results and Analysis 2.1 Effects of different treatments on the survival rate of *Monotropa uniflora* cuttings from Figure 2 It can be seen that the orthogonal experimental treatments have a significant effect on the survival rate of *Monophyllum oxypetalum* cuttings. P <0.05). Statistical analysis on day 45 of cutting culture revealed ( Figure 2In the middle (A) group, treatment 2 (Nymphaea glabra) showed the highest survival rate of cuttings, reaching 97.78%, significantly higher than treatments 5, 8, and 9 by 28.28%, 42.01%, and 83.35%, respectively, but not significantly different from treatments 1, 3, 4, 6, and 7. Treatment 9 had the lowest survival rate at only 53.33%, but not significantly different from treatment 8. On day 90 of the cutting culture, treatment 2 still showed the highest survival rate of cuttings, with treatments 1, 2, and 6 maintaining the same survival rate as on day 45. Other treatments showed some seedling death and a slight decrease in survival rate, with treatment 7 showing a 9% decrease in survival rate, but still significantly higher than treatments 8 and 9, and not significantly different from treatment 2. Figure 2 (B)

[0036] 2.2 Effects of different treatments on the rooting rate of *Mediterranean orientalis* cuttings from Figure 3 It can be seen that the orthogonal experimental treatments had a significant effect on the rooting rate of *Monophyllum oxypetalum* cuttings. P <0.05). On day 45 of the cutting culture, the rooting rate of the *Plectranthus praecox* cuttings in treatment 2 was the highest, at 97.78%, which was not significantly different from treatments 1, 6, and 7, but significantly different from treatments 3, 4, 5, 8, and 9. Among them, the rooting rate of treatment 9 was the lowest, at only 41.11%, but it was not significantly different from treatment 8.

[0037] 2.3 Effects of different treatments on root growth of *Mallotus thomsoniae* cuttings from Figure 4 It can be seen that the orthogonal experimental treatments had a significant effect on the root growth of *Monophyllum indicum* cuttings. P <0.05). Statistical analysis of root growth on day 45 of the cutting culture showed that treatment 2 had the most roots longer than 5cm, with 3.33 roots. This was not significantly different from treatments 1 and 5, but significantly higher than treatments 3, 4, 6, 7, 8, and 9. Treatment 9 had the fewest roots longer than 5cm, with only 0.13 roots. This was not significantly different from treatment 8, but significantly different from treatment 7. Figure 4 (A); The root spread was largest in treatment 1, reaching 6.77 cm, which was not significantly different from treatments 2, 3, 5, and 6, but significantly larger than treatments 4, 7, 8, and 9. Among them, treatment 9 had the smallest root spread at 3.54 cm, which was not significantly different from treatment 8. Figure 4 (B)

[0038] Root growth of each cutting treatment on day 45 is shown in the figure. Figure 5 AI represents processing 1-9 in sequence, from Figure 5 It can be seen that after 45 days of cutting, treatments 1 and 2 had the densest and longest root systems, and the best rooting performance; treatment 5 had dense and relatively long root systems, treatment 6 had fewer root systems and a high proportion of short roots; treatments 8 and 9 had sparse and short root systems, and the rooting effect was poor.

[0039] 2.4 Range Analysis of Orthogonal Experiment Results Table 2 shows the range analysis of the survival rate, rooting rate, number of roots with root length greater than 5 cm, root width, and survival rate of *Monotropa uniflora* cuttings under different treatments on day 45.

[0040] The range analysis results in Table 2 show that the influence of each factor on the survival rate of *Nelumbo nucifera* cuttings on days 45 and 90 is as follows: variety > hormone concentration > treatment time > substrate and hormone concentration > variety > treatment time > substrate. This indicates that variety has the greatest impact on the survival rate of *Nelumbo nucifera* cuttings on day 45, followed by hormone concentration, treatment time, and substrate. Hormone concentration has the greatest impact on the survival rate on day 90, while substrate has the least impact. Based on the k-values ​​of each factor, combination A1B1C3D2 is determined to be the optimal treatment combination.

[0041] The range analysis results in Table 2 show that the influence of each factor on the rooting rate, number of roots longer than 5 cm, and root width of *Nelumbo nucifera* cuttings on the 45th day is as follows: hormone concentration > variety > treatment time > substrate; hormone concentration > treatment time > variety > substrate; and hormone concentration > treatment time > substrate = variety. This indicates that hormone concentration is the key factor affecting the rooting effect of *Nelumbo nucifera* cuttings on the 45th day, while the substrate has the least influence. Based on the k-value, combination A1B1C3D2 is determined to be the optimal treatment combination.

[0042] Table 2. Range analysis results of survival rate and rooting indicators of *Nelumbo nucifera* cuttings. 2.5 Analysis of variance of orthogonal experimental results The results of the ANOVA in Table 3 show that hormone concentration has a significant effect on the survival rate of *Nelumbo nucifera* cuttings on day 45, and a highly significant effect on the rooting rate, number of roots longer than 5 cm, root width, and survival rate on day 90. Variety has a significant effect on the survival rate of *Nelumbo nucifera* cuttings on day 45, and a highly significant effect on the rooting rate on day 45 and the survival rate on day 90, while treatment time and substrate have no significant effect.

[0043] Table 3. Analysis of variance of the effects of various factors in the orthogonal experiment on various indicators of *Monophyllum oxypetalum* cuttings. Note: * indicates that the factor has a significant impact. P <0.05), ** indicates that the factor has a highly significant effect ( P <0.01).

[0044] Therefore, we further conducted multiple comparisons on the effects of different levels of hormone concentration A and variety D on the survival rate and rooting effect of *Nelumbo nucifera* cuttings (Table 4).

[0045] Table 4. Multiple comparisons of the effects of various factors in the orthogonal experiment on various indicators of *Monophyllum oxypetalum* cuttings. Note: In the table, different letters between different levels of the same factor in each column indicate significant differences in the mean. P <0.05), the same as in the table below.

[0046] Table 4 shows the results of multiple comparisons. The effects of hormone concentration and variety levels on the survival rate, rooting rate, and survival rate of *Nelumbo nucifera* cuttings on day 45 and day 90 were as follows: A1 and A2 showed no significant difference, but both were significantly different from A3; D2 showed significant differences from D1 and D3, but D1 and D3 showed no significant difference; the effect of different hormone concentration levels on the number of *Nelumbo nucifera* cuttings with root length greater than 5 cm on day 45 was significant between A1 and A2 and A3, but not significant between A2 and A3; while the effect on root width was not significant between A1 and A2, but both were significantly different from A3.

[0047] In summary, the analysis of variance results show that hormone concentration and variety have a significant impact on the survival and rooting effect of *Nelumbo nucifera* cuttings in this study, while treatment time and substrate ratio have no significant impact. Therefore, the optimal treatment combination A1B1C3D2 obtained from the range analysis is considered to be treatment 2 (A1B2C2D2) in the orthogonal experimental design. The orthogonal experimental results also show that treatment 2 has the best survival rate and rooting effect of *Nelumbo nucifera* cuttings.

[0048] 2.6 Effect of compound bacterial solution on the rooting effect of 'Deep Powder' 'Baolian Lantern' cultivar Table 5 shows that, compared with the untreated group, the compound microbial treatment significantly promoted the root growth of *Plectranthus praecox*, with root emergence occurring more than 7 days earlier. There were no significant differences between different concentrations, and the rooting rate reached 100% at 35 days, a significant increase of 33.92% compared to the untreated group. Figure 6 It can be seen that, compared with the untreated group, the 1:1000 compound bacteria treatment showed vigorous root growth, a large number of roots, thick roots, and mostly white root tips on day 35. In contrast, the 1:500 compound bacteria treatment showed limited root growth on day 35, a smaller number of roots, and some thick roots with white root tips.

[0049] Table 5. Effects of compound microbial treatment on rooting of *Dracaena sanderiana*. Based on the above experimental results, this invention employs an orthogonal experimental design. The results show that hormone concentration has a highly significant impact on the propagation effect of *Nelumbo nucifera* cuttings, while variety significantly affects the survival and rooting rates. Substrate and hormone treatment time have little effect on the propagation effect. A hormone concentration of 100 mg / L IAA + 100 mg / L IBA showed the best effect on *Nelumbo nucifera* cuttings, significantly promoting adventitious root formation and growth; excessively high hormone concentrations, however, inhibited rooting. Cuttings of the *Nelumbo nucifera* 'Ruby Red' variety rooted more easily and faster than the other two varieties, achieving a rooting rate of 97.78% on the 45th day at this hormone concentration (treatment 2). Taking all factors into consideration, for the propagation of *Nelumbo nucifera* 'Deep Pink' through cuttings, it is recommended that cuttings of these three varieties be soaked in a hormone combination of 100 mg / L IAA + 100 mg / L IBA for 15-30 minutes. The cutting substrate should be a mixture of peat moss and coconut coir (2:1) or peat moss, coconut coir, and perlite (4:1:1). Simultaneously, treatment with a compound microbial agent primarily composed of *Bacillus subtilis* significantly promotes root growth, accelerates root emergence, and increases the rooting rate of *Nelumbo nucifera* 'Deep Pink'. The effect of the compound microbial treatment on the root growth of *Nelumbo nucifera* 'Deep Pink' exhibits a concentration effect, with a dilution of 1:1000 showing the best results.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions, characterized in that, Includes the following steps: Semi-lignified branches with a width >1cm were used as cuttings. The base of the cuttings was disinfected and soaked in hormone solution in sequence, and then inserted into the disinfected substrate to obtain cuttings. The hormone solution is prepared by mixing IAA and IBA at a volume ratio of 1:1, and adding 0.5 mL of 1.8% sodium nitrophenolate solution per liter of hormone solution. The matrix consists of peat, coconut coir, and perlite in a volume ratio of 4:1:

1.

2. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that, The disinfection process involves immersing the base of the cuttings in an 800-fold dilution of 50% carbendazim wettable powder for 15 minutes.

3. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that... In the hormone solution, the concentrations of both IAA and IBA are 100 mg / L.

4. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that... The soaking time in the hormone solution is 15-30 minutes.

5. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 4, characterized in that... The soaking time in the hormone solution is 30 minutes.

6. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that, After the cuttings are inserted into the sterilized substrate, the process also includes a step of compacting the substrate around the cuttings.

7. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that, The climate of the location where the *Nelumbo nucifera* cuttings are propagated is a subtropical marine monsoon climate.

8. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that, The varieties of the Lotus Lantern include deep pink, ruby ​​red, and light pink.

9. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 1, characterized in that, It also includes the step of spraying the cuttings with a compound bacterial solution; The compound bacterial solution is composed of Bacillus subtilis ( Bacillus subtilis ), Bacillus licheniformis ( Bacillus licheniformis ) and gelatinous spore-forming bacteria ( Bacillus subtilis The compound bacteria were obtained by mixing them evenly in a mass ratio of 3:1:1, letting them stand for 1 hour, and then adding 15L of water, 0.5 kg of brown sugar and 10g of potassium dihydrogen phosphate. The mixture was then sealed and fermented for 3-5 days. The effective viable count of the compound bacteria is not less than 20 billion / g.

10. The method for propagating *Nelumbo nucifera* seedlings by cuttings in subtropical regions as described in claim 9, characterized in that... Before spraying, the compound bacterial solution is diluted 1000 times.

Images