Coconut coir-carbonized tartary buckwheat shell composite substrate for tobacco seedling raising and seedling raising plate

Abstract

The invention belongs to the technical field of seedling raising, and particularly discloses a coco coir-carbonized tartary buckwheat shell composite substrate for tobacco seedling raising and a seedling raising tray, the composite substrate comprises, by mass, 15% of carbonized tartary buckwheat shells, 8.5% of coco coir and 76.5% of a seedling raising substrate, the seedling raising substrate is a special substrate for tobacco floating seedling raising, the particle size of the seedling raising substrate is 1-5mm, the particle size is larger than or equal to 40%, the total porosity is 80-95%, the pH value is 5.0-7.0, and the conductivity is smaller than or equal to 1000 [mu] s / cm. By the adoption of the coconut coir-carbonized tartary buckwheat shell composite substrate for tobacco seedling raising and the seedling raising tray, the substrate cost and the environmental pressure are reduced, and meanwhile the water retention and air permeability performance and the nutrition supply capacity of the substrate are optimized; the structure and the specification of the seedling-raising tray are optimized, the seedling-raising period is shortened, and the leaf cutting frequency and labor cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of seedling technology, and in particular to a composite substrate of coconut coir and carbonized buckwheat hulls for tobacco seedling cultivation and a seedling tray. Background Technology

[0002] Floating seedling technology has become the main seedling method in China. Currently, a large amount of research has been conducted on tobacco floating seedling substrate materials and formulations, seedling light factors, and nutrient solution pH. However, most studies have neglected the importance of seedling trays. How to improve seedling trays to better reduce the use of seedling substrate, increase the number of seedlings per unit area, and ensure that the quality of tobacco seedlings does not decline is a problem worth exploring.

[0003] Traditional seedling substrates suffer from an imbalance between water retention and aeration, leading to root hypoxia or difficulties in water management, thus affecting seedling uniformity. The mismatch between substrate nutrient release and the seedling's nutrient requirements easily results in early-stage fertilizer burn or late-stage nutrient deficiency, necessitating frequent fertilization. Most alternative materials are costly, limiting their large-scale application. Current conventional substrates face challenges in terms of environmental friendliness, economics, and technological adaptability, requiring material innovation and process optimization to build a sustainable seedling system. This study explores a novel floating tobacco seedling substrate formulation to meet the high-quality requirements of tobacco seedling cultivation and provide a scientific basis for the sustainable development of tobacco production.

[0004] Currently, the main method of seedling cultivation in tobacco-growing areas is to use conventional 160-cell floating seedling trays. The single-cell diameter of the 160-cell conventional floating seedling tray is relatively large, which consumes more substrate and floating tray material. This conventional field seedling cultivation method requires more leaf pruning, has a longer seedling growth period, and has higher labor and input costs.

[0005] Therefore, there is an urgent need to develop an environmentally friendly, economical, and high-performance seedling substrate, which, together with an efficient and energy-saving seedling tray, can solve the technical problems of resource dependence, high cost, and poor seedling quality in traditional flue-cured tobacco seedling cultivation, and achieve sustainable development of tobacco seedling cultivation. Summary of the Invention

[0006] The purpose of this invention is to provide a coconut coir-carbonized buckwheat hull composite substrate and seedling tray for tobacco seedling cultivation, which reduces substrate costs and environmental pressure, while optimizing the substrate's water retention, air permeability and nutrient supply capacity; optimizing the structure and specifications of the seedling tray, reducing substrate usage and floating tray consumables, shortening the seedling cycle, and reducing the number of leaf prunings and labor costs.

[0007] To achieve the above objectives, the present invention provides a coconut coir-carbonized buckwheat hull composite substrate for tobacco seedling cultivation, comprising the following components by mass percentage: 15% carbonized buckwheat hulls, 8.5% coconut coir, and 76.5% seedling substrate. The seedling substrate is a special substrate for tobacco floating seedling cultivation, with a particle size of 1-5mm ≥40%, total porosity of 80%-95%, pH value of 5.0-7.0, and electrical conductivity ≤1000μs / cm.

[0008] Preferably, the carbonized buckwheat hulls are prepared by soaking and washing buckwheat hulls in clean water, drying them, and then carbonizing them in a muffle furnace at a high temperature of 800°C. The coconut coir is processed into coconut shreds after being rinsed and desalted with clean water, or it is obtained by soaking coconut bricks and then naturally drying them.

[0009] The present invention also provides a seedling tray for tobacco seedling cultivation, the seedling tray being filled with the above-mentioned composite substrate, the seedling tray including a seedling tray body, the seedling tray body having 286 holes, the seedling tray body being made of polystyrene foam.

[0010] Preferably, the acupoints are arranged in a horizontal row of 22 acupoints and a vertical row of 13 acupoints.

[0011] Preferably, the holes include an upper hole, a lower hole, and a bottom hole. The upper hole is located on the upper surface of the seedling tray body, and the bottom hole is located on the lower surface of the floating seedling tray body. The upper hole, lower hole, and bottom hole are interconnected from top to bottom.

[0012] Preferably, the upper hole has a size of 18mm×18mm, the lower hole has a size of 12mm×12mm, the bottom hole has a diameter of 6mm, and the thickness is 4mm.

[0013] The advantages and beneficial effects of the above-mentioned coconut coir-carbonized buckwheat hull composite substrate and seedling tray for tobacco seedling cultivation in this invention are as follows: 1. The synergistic application of coconut coir and carbonized buckwheat hulls in this invention significantly optimizes the performance of substrate seedling cultivation: coconut coir provides the substrate with good water buffering properties; carbonized buckwheat hulls provide a continuous supply of nutrients for the early growth of tobacco seedlings. Under appropriate ratio conditions, the two complement each other, effectively suppressing the problems that occur when coconut coir and carbonized buckwheat hulls are used as single substitutes, thereby improving the germination rate and seedling quality while reducing costs.

[0014] 2. The new seedling tray of this invention can save on substrate usage, materials, labor, and seedling costs, and reduce seedling time.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 The seedling emergence rate of various specifications of seedling trays in this invention; Figure 2 This is a seed germination point planting test for the present invention; Figure 3 This invention relates to the treatment of germination potential by carbonizing buckwheat hulls; Figure 4 The germination rate of buckwheat hulls treated with carbonized buckwheat hulls for 14 days according to this invention; Figure 5 This invention relates to the treatment of germination potential with coconut coir. Figure 6 The germination rate of coconut coir treated for 14 days according to this invention; Figure 7 The germination rate of buckwheat hulls treated with carbonized buckwheat hulls according to this invention 14 days after sowing; Figure 8 The bulk density of the matrix under carbonized buckwheat hull treatment according to the present invention; Figure 9 This invention illustrates the effect of different proportions of carbonized buckwheat hulls on the dry weight of the aboveground parts. Figure 10 This invention illustrates the effect of different proportions of carbonized buckwheat hulls on the dry weight of the underground portion. Figure 11 The bulk density of the matrix under carbonized buckwheat hulls and coconut coir treatment according to the present invention; Figure 12 The seedling emergence rate 14 days after sowing is determined by the treatment of coconut coir and carbonized buckwheat hulls according to this invention. Figure 13 The tobacco seedlings (treatment CK) were 45 days after sowing according to this invention. Figure 14 The tobacco seedlings (treatment C1) were 45 days after sowing according to this invention; Figure 15 The dry and fresh weight of tobacco seedlings 60 days after seedling cultivation in Huili area is the present invention. Figure 16 The dry and fresh weight of tobacco seedlings transplanted in Mianning area 60 days after transplanting is the present invention. Figure 17 This is a top view of the seedling tray of the present invention; Figure 18 for Figure 17 AA section diagram; Figure 19 for Figure 17 Cross-sectional view of BB.

[0017] Figure Labels 1. Hole; 2. Upper hole; 3. Lower hole; 4. Bottom hole; 5. Seedling tray body. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] The following examples are not intended to limit the invention, but are only for illustration. Unless otherwise specified, the experimental methods used in the following examples are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0021] Example 1 Seedling trays: such as Figure 17 , Figure 18 , Figure 19 As shown: A 286-cell floating seedling tray is provided, comprising a tray body 5. The tray body 5 has 286 cells 1, arranged in a horizontal row of 22 cells and a vertical row of 13 cells. Each cell 1 includes an upper hole 2, a lower hole 3, and a bottom hole 4. The upper hole 2 is located on the upper surface of the tray body 5, and the bottom hole 4 is located on the lower surface of the tray body 5. The upper hole 2, lower hole 3, and bottom hole 4 are interconnected from top to bottom. The horizontal spacing of the upper hole 2 is 23.2 mm, and the vertical spacing is 24.5 mm. The dimensions of the upper hole 2 are 18 mm × 18 mm. The dimensions of the lower hole 3 are 12 mm × 12 mm. The bottom hole 4 has a diameter of 6 mm and a thickness of 4 mm. The tray body 5 is made of polystyrene foam.

[0022] The seedling substrate is prepared from the following raw materials in the indicated weight ratios: 15% carbonized buckwheat hulls, 7.5% coconut coir, and 76.5% conventional seedling substrate (the seedling substrate mainly includes peat moss, expanded perlite, expanded vermiculite, etc.). The preparation of the above seedling substrate includes the following steps: 1. After soaking and washing the buckwheat hulls in clean water and drying them, carbonized buckwheat hulls are prepared by placing them in a muffle furnace at a high temperature of 800℃.

[0023] 2. Rinse the coconut coir with clean water three times or more to remove most of the salt, then process it into coconut shreds using a grinder. Alternatively, you can buy coconut bricks, soak them in clean water, and then dry them naturally.

[0024] 3. The standard substrate is a special substrate for tobacco floating seedling cultivation, which has been sterilized by both high temperature and microwave.

[0025] 4. Weigh the three substrates according to the proportions, mix them well, and add water until the mixture can be formed into a ball when squeezed in the hand but crumbles when touched.

[0026] By using a seedling substrate with a ratio of 15% carbonized buckwheat hulls, 8.5% coconut coir, and 76.5% conventional substrate, along with a matching 286-cell floating seedling tray, it is possible to: 1. Reduced substrate usage: The substrate volume required per cell is 9804 cubic millimeters, while the substrate volume required for the entire floating seedling tray is 2803944 cubic millimeters. With an increase of 126 cells in the same floating tray area, the substrate usage per cell is reduced by 13058.67 cubic millimeters compared to the original floating tray, a reduction of 57.11%. The substrate usage per tray is reduced by 854723.2 cubic millimeters, a reduction of 23.36%. Based on the current number of seedlings used per acre for transplanting, 0.19 bags of substrate can be saved per acre, which greatly saves substrate usage.

[0027] 2. Material saving: The original 160-cell conventional floating seedling tray consumed 110 grams of polystyrene foam material, while the 286-cell small-hole floating seedling tray consumed 180 grams of material, which is a reduction of 0.059 grams per cell.

[0028] 3. Saves seedling time and leaf pruning frequency: After using the 286-cell small-hole floating seedling method, seedlings are raised and transplanted without leaf pruning. The seedling age is 40-45 days, which saves 20 days of seedling time and reduces the number of leaf pruning times by 3-4 times compared with conventional floating seedling.

[0029] 4. Labor Savings: Based on 50 greenhouses using 160-hole conventional floating seedling trays (144 trays / greenhouse, 8 trays / acre for transplanting, providing 900 acres for transplanting): 150-200 man-days will be saved in leaf pruning (5 greenhouses / person / day, 3-4 pruning sessions); 40 man-days will be saved in seedling management (calculated at 2 management sessions per day, including temperature and humidity management, fertilization, and pest and disease control). In total, 190-240 man-days will be saved, averaging 0.21-0.27 man-days per acre for transplanting seedlings.

[0030] 5. Saves land for seedling cultivation: Compared with conventional floating seedling trays with 160 holes, the 286-hole small-hole floating seedling trays increase the number of holes by 126 per tray in the same area, saving up to 78.75% of the land used for seedling cultivation. On average, this saves 0.0034 mu of land per mu for transplanting seedlings.

[0031] 6. Cost savings in seedling cultivation: Cost savings per transplanted seedling = 0.19 bags / acre of substrate saved. 50 yuan / bag + material saving of 0.07 kg / mu 10 yuan / kg + labor savings of 0.27 person-days / mu 150 yuan / unit + 0.0034 mu / mu of land saved At 800 yuan per mu, based on a tobacco planting area of ​​10,000 mu, the total cost savings are: seedling cost savings of 53.42 yuan per mu. 10,000 mu.

[0032] 7. Improved germination rate of tobacco seeds: The germination rate per 286-cell seedling tray increased by 1.91%.

[0033] 8. Promotes the growth and development of tobacco seedlings: 30 days after sowing, the plant height and number of effective leaves of the new substrate increased by 3.53% and 12.47% respectively compared with the conventional substrate.

[0034] 9. Reduce substrate costs: The cost per seedling tray is reduced by 4.55% compared to conventional substrates.

[0035] Seedling raising method: 1. Weigh out the carbonized buckwheat hulls, coconut coir, and conventional matrix in proportions of 15%, 8.5%, and 76.5%, and mix them thoroughly.

[0036] 2. Fill the holes 1 of the floating seedling tray body 5 with seedling substrate (the substrate moisture is appropriate, and the water content is such that it "can be clumped when squeezed in the hand, but crumbles when touched").

[0037] 3. Apply pressure to acupoints using an acupressure plate.

[0038] 4. Sow seeds using a seeder (sowing depth not exceeding 5mm).

[0039] 5. Cover with substrate.

[0040] 6. Scrape off the substrate from the exposed surface of the tray.

[0041] 7. Place the seedling trays into the seedling pool.

[0042] 8. Seedling Management: The seedling trays are placed in a seedling pool filled with nutrient solution, allowing the entire tray to float on the surface. The substrate in hole 1 is connected to the nutrient solution in the seedling pool through bottom hole 4, absorbing nutrients from the pool using capillary action to keep the substrate moist. After the seeds in hole 1 germinate, the leaves grow upwards and the roots grow downwards, penetrating deep into the substrate and pool water to continuously absorb nutrients from the water, meeting the growth needs of the tobacco seedlings throughout the entire seedling growth period, ultimately cultivating robust tobacco seedlings.

[0043] 9. Fertilize 3-4 times. The first fertilization is done when the seedlings are 50% emerged, using a nutrient solution with a nitrogen concentration of 50 mg / kg. The second fertilization is done at the small cross stage (around 20 days), using a nutrient solution with a nitrogen concentration of 100 mg / kg. The third fertilization is done at the large cross stage (around 30 days), using a nutrient solution with a nitrogen concentration of 100 mg / kg. In the last two weeks (seedling stage), a fourth fertilization is done based on the seedling growth, using a nutrient solution with a nitrogen concentration of 50 mg / kg. Fertilizer is not necessary if the seedlings show no signs of nutrient deficiency. When fertilizing, first dissolve the seedling fertilizer in clean water in a bucket (pot), then pour it into the pond water from multiple points, stirring thoroughly. It is strictly forbidden to add fertilizer solution or water from above the surface of the tray.

[0044] Verification Example I. Verification of the seedling trays The tested flue-cured tobacco variety was Yunyan 87. Seven representative seedling trays were collected from Yunnan and Sichuan provinces (Table 1). The experiment was conducted in a randomized block design with three replicates, and each plot consisted of four seedling trays. Floating seedling cultivation was used in a greenhouse. Sowing was carried out on March 7th, with one seed sown per hole. The first fertilization was applied when 50% of the seedlings emerged, and the second fertilization was applied at the large cross stage. Fertilizer application and other seedling management methods followed the flue-cured tobacco seedling fertilization methods in the "Liangshan Prefecture 2017 Specialized Seedling Technology Program". Seedlings from all sizes of seedling trays were transplanted to the field after reaching four leaves and one heart, with conventionally grown seedlings serving as a control.

[0045] Table 1. Specifications of Seedling Trays

[0046] 1. The effect of different seedling tray sizes on germination rate from Figure 1 and Figure 2 It can be seen that there are significant differences in germination rates among the seedling trays. The seedling trays with 286, 160, and 338 wells have the highest germination rates, ranging from 91.12% to 95.69%. The seedling trays with 504, 595, and 209 wells have slightly lower germination rates, ranging from 82.3% to 85.1%. The improved 160-well tray has the lowest germination rate, at only 78.75%.

[0047] Table 2. Pearson correlation analysis between different seedling tray sizes and various indicators of flue-cured tobacco seedlings.

[0048] The analysis of Table 2 and Table 1 shows that the three seedling trays with the highest germination rates (160, 286, and 338 cells) all had a depth of ≥4.8 cm; while the seedling trays with low germination rates all had a depth between 3.4 and 3.8 cm. This indicates that if the seedling trays are too shallow, the germination rate will be affected, and the depth needs to be maintained above 4.8 cm.

[0049] 2. The effect of different seedling tray sizes on seedling growth period Table 3. Effects of different seedling tray sizes on seedling growth period

[0050] Table 3 shows that after sowing on March 7th, all treatments reached the emergence stage in 10-11 days; the small cross-shaped stage in 22-23 days; the 160-cell (CK) seedlings reached the seedling stage in 44 days, while the other varieties reached the seedling stage in 40-41 days. Except for CK, the seedling emergence time for the other six varieties was basically the same. Combined with the analysis in Table 2, tray depth is the main factor affecting the seedling growth period. CK has the deepest trays, resulting in the longest growth period, 3-4 days longer than the other varieties. The depth of the other six varieties ranges from 3.0 to 4.8 cm, allowing for seedling transplanting 40-41 days after sowing and 29-31 days after emergence. Therefore, excessively deep trays prolong the seedbed period; a depth of less than 6.0 cm is preferable.

[0051] 3. The effects of different seedling tray sizes on major agronomic traits and seedling quality Table 4. Main agronomic traits of each seedling tray specification (measured 41 days after sowing)

[0052] Table 4 shows that, except for CK, the seedlings of other specifications emerged 41 days after sowing. At this time, the agronomic traits of the seedlings were measured. Table 4 shows that the seedling height of all specifications ranged from 4.4 to 5.5 cm, and the stem height ranged from 2.6 to 3.3 cm. The 338-cell seedling tray had the highest seedling height, significantly higher than CK. The stem circumference of the 338-cell tray was significantly higher than other specifications, exceeding the lowest 504-cell and 595-cell trays by 66.7%. While its seedling height and stem height met the standards for seedling establishment, the number of true leaves was lower. There were significant differences in root volume among the specifications, with the improved 160 and 209-cell trays having the highest, while the 160, 504, and 595-cell trays had lower volumes, with a difference of nearly 100%. A larger root volume indicates a more developed root system, which is more beneficial for seedling recovery after transplanting. Root dry weight was higher in the 160, improved 160, and 209-cell trays, significantly lower in other specifications, with a difference of nearly 100% between the lowest and highest. The stem and leaf dry weight was highest in 160-well and modified 160-well discs, followed by 209-well and 338-well discs, and lowest in 286-well and discs with more than 500 wells. The overall plant dry weight showed the same trend as the stem and leaf dry weight.

[0053] Table 5. Effects of different seedling tray sizes on seedling survival rate and robust seedling rate of flue-cured tobacco.

[0054] Table 5 shows that the stem height compliance rate was significantly lower in the 160-well tray than in the other treatments, with no significant differences among the other trays, ranging from 84.3% to 98.1%. The true leaf number compliance rate exceeded 96.7% in all treatments, with no significant differences among treatments. The seedling survival rate was lowest in the 160-well tray at 73.3%, with no significant differences among the other treatments. Specifically, the improved 160, 338, and 504-well trays all exceeded 90%. The seedling vigor rate was also lowest in the 160-well tray, significantly lower than the other treatments except for 504; the highest was in the improved 160-well tray, followed by the 338, 209, and 286-well trays.

[0055] 4. Post-transplanting seedling recovery and field growth Table 6. Effects of different seedling tray sizes on the time and rate of seedling establishment in flue-cured tobacco fields.

[0056] Table 6 shows that the recovery time for all transplanted seedlings was 1 day, which is 2 days earlier than that for conventional transplanting of larger seedlings. A survey 4 days after transplanting showed a recovery rate of ≥98.7%. A survey 6 days after transplanting showed a recovery rate remaining above 95.0%. This indicates that transplanted seedlings recover quickly, within 1 day, with a recovery rate of over 98%. Therefore, the size of the transplanting tray has no significant impact on the recovery time and rate.

[0057] 5. Comparison of seedling costs among different seedling tray sizes Table 7. Seedling Costs for Different Seedling Tray Specifications

[0058] Table 7 shows that, generally, the more cells in the tray, the lower the seedling cost. For small seedlings, the 595-cell tray has the lowest cost, while the 160-cell tray has the highest. Using 595-cell trays for small seedling cultivation costs nearly three times less than conventional large seedling cultivation, resulting in a cost saving of 1284 yuan / hm². 2 .

[0059] When selecting seedling trays for under-film transplanting of flue-cured tobacco seedlings, factors such as seedling emergence rate, agronomic traits, seedling quality, seedling establishment and robustness rate, field recovery rate, vigorous growth during the peak growing season, and seedling cost should be comprehensively considered. The key parameters for selecting seedling trays include the area of ​​the planting hole, seedling density, and tray depth. Based on regression equations, a tray depth of 4.0–5.0 cm and a planting hole area of ​​6–10 cm² are recommended. 2 The density of tobacco seedlings is between 120 and 160 plants / m². 2 Between. Taking into account the growth of tobacco seedlings and costs, a seedling tray with 286 cells was selected, and the substrate ratio of the seedling tray was studied. Finally, the optimal ratio of coconut coir-carbonized buckwheat hull synergistic substitution was determined.

[0060] II. Research on Seedling Raising Mechanism and Proportioning 1. Study on the basic properties of carbonized buckwheat hulls and coconut coir Sufficient amounts of the two alternative substrates were dried and ground through a 40-mesh sieve. Based on the conventional substrate replacement amount of the three materials in the seedling experiment, the alternative materials were weighed according to the ratio and placed in a 1000ml Erlenmeyer flask. 500ml of distilled water was added, the flask was sealed with sealing film, and the mixture was shaken on a shaker at 25℃ for 30 minutes. After soaking for 48 hours, the mixture was filtered into a 500ml Erlenmeyer flask to obtain the substrate extract. The concentrations of each extract are shown in Tables 8 and 9.

[0061] Table 8 Concentration of Carbonized Buckwheat Hull Extract

[0062] Table 9 Concentration of Coconut Coir Extract

[0063] After the extract was prepared, its pH, EC value, and nitrogen, phosphorus, and potassium contents were determined. pH, total nitrogen, total phosphorus, and total potassium contents were determined using the Boschman method; the EC value was determined using a conductivity meter. The obtained data are shown in Table 10-11.

[0064] Table 10. pH, EC values, and nitrogen, phosphorus, and potassium contents under carbonized buckwheat hull treatment.

[0065] Table 11 pH, EC value, and nitrogen, phosphorus, and potassium content under coconut coir treatment.

[0066] Tables 10 and 11 show that the addition of carbonized buckwheat hulls and coconut coir both increased the pH of the extract, which was higher than that of the control, and the pH increased with the increase of their proportions. The EC value, total nitrogen, and total phosphorus content of the extract were all positively correlated with the amount of carbonized buckwheat hulls added, with the highest values ​​in treatment T4, but the total potassium content was the highest in treatments T2 and T3. The EC value, total nitrogen, total phosphorus, and total potassium content of the extract were all positively correlated with the amount of coconut coir added, with the highest total nitrogen in treatment C1 and the highest total potassium in treatment C4. The pH, EC value, total nitrogen, total phosphorus, and total potassium content of the extract were the highest under the carbonized buckwheat hull treatment.

[0067] 2. Study on seed germination characteristics under treatment with extracts of different proportions of alternative materials. The evaporated extracts from each treatment were replenished daily at 3 PM. Starting on day 4, the number of germinated seeds was counted, ending on day 14 (germination was defined as the radicle exceeding half the seed length). On day 14, 10 seedlings were randomly selected from each treatment, and their length was measured. The formulas for calculating the relevant indicators are as follows: Germination rate (%) = Number of normally germinated seeds on the 14th day after placement in the seedbed / Number of seeds tested × 100%. In the experiment, moldy seeds were disinfected with 95% alcohol and returned to their original place for continued observation. Severely moldy seeds were picked out to avoid infecting other seeds and were recorded as ungerminated seeds.

[0068] Germination potential (%) = Number of normally germinated seeds on the 7th day after placement in the seedbed / Number of seeds tested × 100%.

[0069] like Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, among the various treatments of carbonized buckwheat hulls, T1, T2, and T4 treatments all improved the germination rate of the Honghua Dajinyuan variety. The T4 treatment rapidly increased the initial emergence rate, which may be related to the higher nutrient concentration of this treatment, which better supplies nutrients for seed growth after germination. Results 14 days after sowing showed that the Honghua Dajinyuan seeds responded best to the T1 treatment, possibly because the extract concentrations of the other treatments were too high, thus affecting the subsequent growth of the seedlings. For Yunyan 87, the T2 treatment improved the germination rate of Yunyan 87. In the early germination rate of the 87 variety, treatment T1 showed the greatest improvement in emergence rate at 14 days after sowing. At 14 days after sowing, the germination rate decreased with increasing concentration of carbonized buckwheat hull extract, with a significant peak observed in treatment T1. Among the treatments with added coconut coir, C1, C2, and C3 were beneficial to the germination of the Yunyan 87 variety, while treatments C1 and C4 improved the germination rate of the Honghua Dajinyuan variety. In summary, treatments with appropriate concentrations of carbonized buckwheat hull extract and coconut coir are beneficial to the germination of different tobacco varieties.

[0070] 3. Study the appropriate ratio of carbonized buckwheat hulls, coconut coir, and conventional substrate. The experiment was conducted at the National Tobacco Cultivation Physiology and Biochemistry Research Base of Henan Agricultural University, using Yunyan 87 as the test variety. The experiment consisted of three rounds, with treatments listed in the table below. The substrate ratios for each treatment were determined based on substrate weight and bulk density, as shown in Tables 12-14. A conventional tobacco floating seedling substrate (hereinafter referred to as the conventional substrate) was used as a control. The conventional substrate, sourced from Kunming Aimore Technology Development Co., Ltd., had a particle size (1-5 mm) ≥40%, total porosity of 80%-95%, pH of 5.0-7.0, and electrical conductivity (μs / cm) ≤1000. Sowing was carried out on December 8, 2023, and the seedlings were cultivated in an artificial incubator at a temperature of 27℃, humidity of 80%, and a day length of 12 hours. During the seedling stage, the water level in the nutrient tank was maintained at approximately 10 cm. Routine management followed the conventional tobacco floating seedling cultivation techniques.

[0071] Table 12 Matrix ratios for each treatment in the first round of carbonized buckwheat hull processing

[0072] Table 13 Matrix ratios for each treatment in the second round of carbonized buckwheat hull processing

[0073] Table 14 Substrate ratios for each treatment in the third round of carbonized buckwheat hull processing

[0074] After the substrate was mixed, the bulk density of the substrate was determined using a ring sampler-drying method. The germination rate was then investigated and calculated.

[0075] Thirty days after sowing, five tobacco seedlings with uniform growth and appearance that can represent the growth status of the seedling tray were selected and marked. Every seven days, the agronomic traits of the tobacco seedlings were measured according to the tobacco industry standard YC / T142—2010 "Methods for Investigating Agronomic Traits of Tobacco". These traits included seedling height, stem circumference, maximum leaf length and width, leaf color, and number of leaves.

[0076] While conducting agronomic trait surveys, three additional tobacco seedlings were taken from each plot. After separating the roots, stems and leaves, the roots were first scanned using a root scanner and then dried to determine the dry matter accumulation. The measured indicators were as follows: aboveground fresh weight and dry weight, root fresh weight and dry weight, total root length, total surface area, root volume and number of root tips.

[0077] The formulation cost relates to the producer's choice of raw materials and ultimately affects the product's competitiveness in the market. By calculating the cost of conventional and alternative substrates used in different proportions, the price per kilogram of substrate for each treatment can be obtained, thereby estimating the cost per tray of substrate and the cost of substrate per seedling. The differences in cost between different treatments can be determined by comparing with conventional substrate.

[0078] Given that the main purpose of the first two rounds of experiments was to screen the appropriate single matrix replacement ratio of carbonized buckwheat hulls and optimize it in one step, the matrix ratio of each treatment in the third round of experiments was finally determined. Therefore, the focus will be on analyzing the data obtained from the third round of experiments.

[0079] Depend on Figure 7 It can be seen that the overall germination rate of the treatment with added carbonized buckwheat hulls 14 days after sowing was significantly different from that of the control, with the germination rate ranging from 71.42% to 80.51%. Among them, the T1 treatment had the highest germination rate of 80.51%, which was 6.49% higher than that of the CK.

[0080] Depend on Figure 8 It can be seen that, compared with the control (CK), the bulk density of carbonized buckwheat hulls decreased by 0.74%, 2.86%, 3.48%, 4.55%, and 5.38% at T1 to T5, respectively. The bulk density gradually decreased with the increase of the proportion of carbonized buckwheat hulls.

[0081] Table 15 Effects of carbonized buckwheat hulls on tobacco seedling growth and development

[0082] As shown in Table 15, 40 days after seedling emergence, the agronomic traits of tobacco seedlings showed a trend of first increasing and then decreasing with the increase of the amount of carbonized buckwheat hulls added. Among them, the T3 treatment showed the best agronomic traits, with its plant height significantly higher than the control by 11.33 cm, an increase of 65.88%, followed by the T1 treatment. 50 days after seedling emergence, the overall trend of the treatments was basically the same as the previous period, with the T3 treatment still showing the best agronomic traits. Among them, the agronomic traits of tobacco seedlings in the T4 and T5 treatments increased significantly compared with the previous period, indicating that the carbonized buckwheat hulls had a more significant effect on promoting the growth of tobacco seedlings in the later stage.

[0083] Table 16 Effects of carbonized buckwheat hulls on root growth and development

[0084] As shown in Table 16, 30 days after seedling raising, the root length of the T4 treatment was significantly higher than that of the control, with an increase of 385.95% to 605.02 cm. In addition, the root surface area of ​​the T4 treatment increased by 472.29% compared with the control, and its root volume and root tip number also increased significantly compared with the control. This indicates that the T4 treatment can effectively promote the growth and development of tobacco seedlings.

[0085] Depend on Figure 9 It can be seen that 30 days after seedling raising, the aboveground dry weight of treatment T3 was greater than that of the other treatments, increasing by 118.75% compared to CK, to 0.35g. The aboveground dry weight of treatments T1 and T4 was second only to treatment T3, while treatment CK had the lightest aboveground dry weight at 0.16g. 60 days after seedling raising, treatment T2 had the largest aboveground dry weight at 0.86g, followed by treatments T3 and T4. The aboveground dry weight of the other treatments was lower than that of CK.

[0086] Depend on Figure 10 It can be seen that 30 days after seedling raising, the underground dry weight of the T3 treatment was greater than that of the other treatments, the underground dry weight of the T4 and T5 treatments was second only to the T3 treatment, and the underground dry weight of the CK treatment was the lightest. 60 days after seedling raising, the underground dry weight of the T2 treatment was the largest, followed by the T3 and T4 treatments, and the underground dry weight of the other treatments was comparable to that of the CK.

[0087] Table 17 Costs of various substrates under carbonized buckwheat hull treatment

[0088] As can be seen from Table 17, the cost of each treatment after adding carbonized buckwheat hulls was lower than that of conventional substrates, and the cost gradually decreased with the increase of the proportion of carbonized buckwheat hulls. The cost of a single seedling tray for T1 was 0.89% lower than that for CK, at RMB 1.5284, and the cost of a single seedling tray for T5 was 0.87% lower than that for CK, at RMB 1.5296.

[0089] The coconut coir substrate substitution experiment was conducted at the National Tobacco Cultivation Physiology and Biochemistry Research Base of Henan Agricultural University, using Yunyan 87 as the test variety. Treatments are shown in Table 18. The substrate ratios for each treatment were determined based on substrate weight and bulk density, as shown in the table below. A conventional tobacco floating seedling substrate (hereinafter referred to as the conventional substrate) was used as a control. The conventional substrate was sourced from Kunming Aimore Technology Development Co., Ltd., with a particle size (1-5mm) ≥40%, total porosity 80%-95%, pH value 5.0-7.0, and electrical conductivity (μs / cm) ≤1000. Sowing was carried out on December 8, 2023, and the seedlings were cultivated in an artificial incubator at a temperature of 27℃, humidity of 80%, and a day length of 12 hours. During the seedling stage, the water level in the nutrient tank was maintained at approximately 10cm. Routine management followed the conventional tobacco floating seedling cultivation techniques.

[0090] Table 18 Substrate ratios for each treatment

[0091] After the substrate was mixed, the bulk density of the substrate was determined using a ring sampler-drying method. The germination rate was then investigated and calculated.

[0092] Thirty days after sowing, five tobacco seedlings with uniform growth and appearance that can represent the growth status of the seedling tray were selected and marked. Every seven days, the agronomic traits of the tobacco seedlings were measured according to the tobacco industry standard YC / T142—2010 "Methods for Investigating Agronomic Traits of Tobacco". These traits included seedling height, stem circumference, maximum leaf length and width, leaf color, and number of leaves.

[0093] While conducting agronomic trait surveys, three additional tobacco seedlings were taken from each plot. After separating the roots, stems and leaves, the roots were first scanned using a root scanner and then dried to determine the dry matter accumulation. The measured indicators were as follows: aboveground fresh weight and dry weight, root fresh weight and dry weight, total root length, total surface area, root volume and number of root tips.

[0094] The formulation cost relates to the producer's choice of raw materials and ultimately affects the product's competitiveness in the market. By calculating the cost of conventional and alternative substrates used in different proportions, the price per kilogram of substrate for each treatment can be obtained, thereby estimating the cost per tray of substrate and the cost of substrate per seedling. The differences in cost between different treatments can be determined by comparing with conventional substrate.

[0095] Table 19 Effects of coconut coir on agronomic traits of tobacco seedlings

[0096] Table 19 shows that 30 days after seedling establishment, the stem circumferences of C1, C3, and C4 were significantly lower than those of the control (CK), at 1.02 cm, 0.90 cm, and 1.42 cm, respectively. The maximum leaf width of C4 was significantly lower than that of CK, at 3.03 cm. 45 days after seedling establishment, the plant height of C1 was significantly higher than that of CK, at 9.18 cm, and the number of effective leaves in C2 was significantly higher than that of CK, at 5.33. 60 days after seedling establishment, the plant height of C1 was also significantly higher than that of CK, at 12.03 cm, and the maximum leaf width of C2 was significantly higher than that of the control. However, there were no significant differences in maximum leaf length and number of effective leaves between the treatments with different coconut coir ratios and the control group.

[0097] Table 20 Costs of various substrates under coconut coir treatment

[0098] As can be seen from Table 20, the cost of each treatment after adding coconut coir is lower than that of conventional substrate, and the cost gradually decreases as the proportion of coconut coir increases. The cost of a single seedling tray of C1 is 35.71% lower than that of CK, at RMB 0.99, and the cost of a single seedling tray of C4 is 66.88% lower than that of CK, at RMB 0.51.

[0099] Three rounds of research showed that mixing different materials with conventional substrates reduced the substrate bulk density to varying degrees. Among them, carbonized buckwheat hulls had a relatively small impact on substrate bulk density; when added at a ratio of 15%–25%, the bulk density of the carbonized buckwheat hull substrate decreased by only 0.74%–5.38% compared to the conventional substrate. However, coconut coir combined with carbonized buckwheat hulls had a significant impact on bulk density, even at the minimum addition ratio, resulting in a substantial change in substrate bulk density. Regarding germination rate, in the early seedling stage, the overall germination rate of the carbonized buckwheat hull treatment was higher than that of the conventional substrate, while the germination rates of the coconut coir and carbonized buckwheat hull treatments were slightly lower than those of the conventional substrate. As the growth period progressed, at 14 days after seedling emergence, the germination rate of the treatment with 15% carbonized buckwheat hulls was significantly higher than that of the control, indicating that the addition of low concentrations of carbonized buckwheat hulls can promote seed germination. Comparing overall agronomic traits, it was found that the tobacco seedlings treated with carbonized buckwheat hulls exhibited significantly better overall growth than the control. The treatment with 20% carbonized buckwheat hulls significantly increased plant height and maximum leaf length, indicating that adding 20% ​​carbonized buckwheat hulls promotes rapid growth during the seedling stage, achieving the goal of early emergence and rapid growth. Comparing root development, it was found that the root development of the carbonized buckwheat hulls treatment was significantly better than the control, with the treatment with 15% carbonized buckwheat hulls showing the best root growth. Overall, carbonized buckwheat hull treatment better promotes tobacco seedling growth and nutrient absorption, while the addition of coconut coir can stabilize seedling emergence rate while increasing root growth and significantly reducing costs. Considering all factors, adding 20% ​​carbonized buckwheat hulls to the conventional substrate is the most suitable option.

[0100] Based on the experiment, it can be seen that an appropriate ratio of coconut coir can increase the water absorption of the substrate, improve the germination rate, and reduce the substrate cost. Therefore, under the premise of selecting an appropriate ratio of carbonized buckwheat hulls, we will explore the appropriate ratio of coconut coir-carbonized buckwheat hull synergistic substitution.

[0101] III. Research on the appropriate ratio of carbonized buckwheat hulls to coconut coir as a synergistic substitute The experiment was conducted at the National Tobacco Cultivation Physiology and Biochemistry Research Base of Henan Agricultural University, using Yunyan 87 as the test variety. Four treatments were set up, as shown in the table below. The substrate ratios for each treatment were determined based on substrate weight and bulk density, as shown in Table 21. A conventional tobacco floating seedling substrate (hereinafter referred to as conventional substrate) was used as a control. The conventional substrate was sourced from Kunming Aimore Technology Development Co., Ltd., with a particle size (1-5mm) ≥40%, total porosity 80%-95%, pH value 5.0-7.0, and electrical conductivity (μs / cm) ≤1000. Sowing was carried out on December 8, 2023, and the seedlings were cultivated in an artificial incubator at a temperature of 27℃, humidity of 80%, and a day length of 12 hours. During the seedling stage, the water level in the nutrient tank was maintained at approximately 10cm. Routine management followed the conventional tobacco floating seedling cultivation techniques.

[0102] Table 21. Proportion of Carbonized Tartary Buckwheat Hull-Coconut Coarse Synergistic Substrate Alternatives

[0103] After the substrate was mixed, the bulk density of the substrate was determined using a ring sampler-drying method. The germination rate was then investigated and calculated.

[0104] The formulation cost relates to the producer's choice of raw materials and ultimately affects the product's competitiveness in the market. By calculating the cost of conventional and alternative substrates used in different proportions, the price per kilogram of substrate for each treatment can be obtained, thereby estimating the cost per tray of substrate and the cost of substrate per seedling. The differences in cost between different treatments can be determined by comparing with conventional substrate.

[0105] Depend on Figure 11 It can be seen that, compared with the control (CK), the bulk density values ​​of carbonized buckwheat hulls and coconut coir treatments decreased by 11.76%, 27.37% and 44.72% in C1 to C3, respectively, and the bulk density decreased as the proportion of coconut coir increased.

[0106] Depend on Figure 12 It can be seen that after adding coconut coir and carbonized buckwheat hulls, the overall germination rate of the treatment did not change significantly 14 days after sowing, with the germination rate ranging from 71.42% to 73.57%. Among them, the germination rate of the C2 treatment was closest to that of the CK, with a difference of only 0.45%.

[0107] Table 22 Costs of various substrates under coconut coir and carbonized buckwheat hull treatments

[0108] As can be seen from Table 22, the cost of each treatment after adding coconut coir and carbonized buckwheat hulls is lower than that of conventional substrate, and the cost gradually decreases with the increase of coconut coir ratio. The cost of a single seedling tray of C1 is 8.44% lower than that of CK, at RMB 1.41, and the cost of a single seedling tray of C4 is 35.71% lower than that of CK, at RMB 0.93.

[0109] from Figure 13-14 It can be seen that, compared with CK, C1 has uniform growth and good growth condition. C1 has a higher seedling rate and faster growth rate, and its plant height is significantly higher than that of CK. C2 and C3 have low seedling rates and cannot grow normally.

[0110] The experimental results showed that the germination rate of tobacco seeds in treatments C1 and C2 was lower than that in treatment CK. The synergistic substitution of carbonized buckwheat hulls and coconut coir had a significant impact on the growth and development of tobacco seedlings. Treatment C1 promoted seedling growth and development, while the growth and development of seedlings in the other treatments were lower than that in treatment CK. In summary, C1 is beneficial for tobacco seedling cultivation, while C2 and C3 have negative effects on seedling growth and development.

[0111] Subsequently, a field seedling trial was conducted in Huili and Mianning areas using 60% coconut coir and 15% buckwheat hulls.

[0112] Depend on Figure 15 It can be seen that the fresh and dry weights of the aboveground and underground parts of the coconut coir and buckwheat hull treatments were higher than those of the control (CK). The fresh weight of the leaves of the coconut coir and buckwheat treatments were 22.86% and 25.71% higher than those of the control, respectively. The fresh weight of the stems of the coconut coir and buckwheat treatments were 20.37% and 22.22% higher than those of the control, respectively. The fresh weight of the roots of the coconut coir and buckwheat hull treatments were 2.94% and 11.76% higher than those of the control, respectively.

[0113] Table 23 Agronomic traits of tobacco seedlings 60 days after seedling raising in Huili area

[0114] As shown in Table 23, there were no significant differences in maximum leaf length and maximum leaf width among the three treatments in Huili area. Compared with the control (CK), the plant height of 60% coconut coir was significantly increased by 17.80%, while the stem circumference was decreased by 17.78%. Compared with the control (CK), the plant height of 15% buckwheat was significantly increased by 22.86%, and the number of effective leaves was significantly increased by 37.10%.

[0115] Depend on Figure 16 It can be seen that the fresh and dry weights of the aboveground and underground parts of the coconut coir and buckwheat hull treatments were higher than those of the control (CK). The fresh weight of the leaves was 13.89% and 55.56% higher than that of the control (CK) in the coconut coir and buckwheat treatments, respectively. The fresh weight of the stems was 4.29% and 11.43% higher than that of the control (CK) in the coconut coir and buckwheat treatments, respectively. The fresh weight of the roots was 7.61% and 32.61% higher than that of the control (CK) in the coconut coir and buckwheat hull treatments, respectively.

[0116] Table 24 Agronomic traits of tobacco seedlings 60 days after seedling raising in Mianning area

[0117] As shown in Table 24, there were no significant differences in stem circumference and number of effective leaves among the three treatments in Mianning area. Compared with the control group, the plant height of 60% coconut coir was reduced by 9.78%, and the stem circumference was significantly reduced by 12.06%. Compared with the control group, the plant height of 15% buckwheat was reduced by 7.19%, the stem circumference was reduced by 12.10%, and the maximum leaf width was reduced by 19.73%.

[0118] Table 25 Substrate Costs for Each Treatment in Field Trials

[0119] As shown in Table 25, the cost of 60% coconut coir and 15% buckwheat substrate is lower than that of CK, by 43.51% and 0.66% respectively.

[0120] Considering the adaptability for field promotion and the cost of the substrate, the optimal mixing ratio was ultimately selected as 15% carbonized buckwheat hulls + 8.5% coconut coir + 76.5% conventional seedling substrate.

[0121] Therefore, this invention employs the aforementioned coconut coir-carbonized buckwheat hull composite substrate and seedling tray for tobacco seedling cultivation. Coconut coir imparts excellent moisture buffering properties to the substrate; carbonized buckwheat hulls provide a continuous supply of nutrients for the early growth of tobacco seedlings. Under suitable mixing conditions, the two complement each other, improving germination rate and seedling quality while reducing costs. The seedling tray can save on substrate usage, materials, labor, and seedling costs, and reduce seedling time.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A composite substrate of coconut coir and carbonized buckwheat hulls for tobacco seedling cultivation, characterized in that, The components include the following percentages by weight: 15% carbonized buckwheat hulls, 8.5% coconut coir, and 76.5% seedling substrate. The seedling substrate is a special substrate for tobacco floating seedling cultivation, with a particle size of 1-5mm ≥40%, total porosity of 80%-95%, pH value of 5.0-7.0, and electrical conductivity ≤1000μs / cm.

2. The coconut coir-carbonized buckwheat hull composite substrate for tobacco seedling cultivation according to claim 1, characterized in that: The carbonized buckwheat hulls are prepared by soaking and washing buckwheat hulls in clean water, drying them, and then carbonizing them in a muffle furnace at a high temperature of 800℃. The coconut coir is processed into coconut shreds after being rinsed and desalted with clean water, or it is obtained by soaking coconut bricks and then naturally drying them.

3. A seedling tray for tobacco seedling raising, characterized in that: The seedling tray is filled with the composite substrate according to any one of claims 1-2. The seedling tray includes a seedling tray body with 286 holes. The material of the seedling tray body is polystyrene foam.

4. The seedling tray for tobacco seedling raising according to claim 3, characterized in that: The acupoints are arranged in two rows: 22 horizontally and 13 vertically.

5. The seedling tray for tobacco seedling raising according to claim 3, characterized in that: The holes include an upper hole, a lower hole, and a bottom hole. The upper hole is located on the upper surface of the seedling tray body, and the bottom hole is located on the lower surface of the floating seedling tray body. The upper hole, lower hole, and bottom hole are interconnected from top to bottom.

6. The seedling tray for tobacco seedling raising according to claim 5, characterized in that: The upper hole measures 18mm × 18mm, the lower hole measures 12mm × 12mm, the bottom hole has a diameter of 6mm, and a thickness of 4mm.

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