A method for raising tobacco blanket seedlings

Abstract

The invention provides a tobacco blanket seedling raising method, which belongs to the technical field of tobacco blanket seedling raising. The tobacco blanket seedling raising method comprises the following steps: adding clean water to a sowing matrix, mixing the mixture, and loading the mixture into a seedling raising tray; watering the sowing matrix with a sprayer after loading the mixture until water seeps out from under the seedling raising tray; selecting seedling raising seeds; burying the seedling raising seeds in the sowing matrix of the seedling raising tray, and covering the seeds with a thickness of 2 mm with fine soil; raising the seedlings; watering and fertilizing the seeds during the seedling raising period; cutting the leaves twice during the seedling raising process; and when the seedling raising seeds grow into strong seedlings, the tobacco blanket seedling raising is completed. The invention provides a tobacco blanket seedling raising method, which can solve the problems that the blanket seedlings cultivated by the traditional seedling raising method have insufficient root system binding force, cannot become strong seedlings, reduce the quality of the blanket seedlings, have too high a loss rate during the transplanting process, and cannot meet the precise position requirements of the planting arm for the blanket block and the tobacco seedlings, thereby improving the efficiency of the fully automatic mechanized transplanting of tobacco.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco blanket seedling cultivation, and in particular relates to a tobacco blanket seedling cultivation method. Background Art

[0002] The development of modern agriculture has put forward new requirements for the seedling and transplanting links of my country's tobacco industry. At present, the connection between tobacco seedling and transplanting links in my country is low, the matching degree is poor, and the construction of automated transplanting and seedling systems is imperfect. Therefore, how to build a new seedling and transplanting system is an important research direction. As a seedling technology that matches high-speed transplanting, tobacco blanket seedling cultivation is of great significance in promoting the integration of agricultural machinery and agronomy in my country's tobacco transplanting, and promoting the simplification, scale and mechanization of tobacco production. Tobacco blanket seedling cultivation uses flat trays to cultivate tobacco seedlings. After the seedlings are mature, the roots are coiled into a blanket and connected together. The ultimate goal of its seedling cultivation is to use the operating principle of the rice high-speed transplanter to realize the mechanical transplanting of tobacco seedlings, solve the problems of high cost, low efficiency and high labor intensity in the tobacco transplanting link, and improve the mechanization of tobacco transplanting in my country. Tobacco blanket seedling cultivation is similar to the blanket seedling cultivation technology of rice and rapeseed. It has high requirements for the quality of seedlings, requiring the seedlings to be "rooted blanket, high density, short and strong".

[0003] The blanket seedlings cultivated by traditional seedling raising methods lack root binding strength and cannot become strong seedlings, which reduces the quality of the blanket seedlings. The loss rate during transplanting is too high and the planting arm cannot meet the precise positioning requirements of the blanket and tobacco seedlings. The efficiency of fully automatic mechanized tobacco transplanting is low. Summary of the invention

[0004] In view of this, the present invention provides a tobacco blanket seedling raising method, which can solve the problems that the blanket seedlings cultivated by the traditional seedling raising method have insufficient root coiling strength and cannot become strong seedlings, resulting in reduced quality of the blanket seedlings, too high loss rate during transplanting and inability to meet the precise positioning requirements of the planting arm for the blanket blocks and tobacco seedlings, thereby improving the efficiency of fully automatic mechanized tobacco transplanting.

[0005] The present invention is achieved in that:

[0006] The present invention provides a method for growing tobacco blanket seedlings, which comprises the following steps:

[0007] S10: Add clean water to the sowing substrate and mix well, and put it into the seedling tray; the amount of water added is enough to form a ball by hand;

[0008] S20: After placing the seed tray, use a sprayer to water the seeding medium sufficiently until water seeps out from under the seedling tray;

[0009] S30: selecting seeds for seedling cultivation, wherein the seeds for seedling cultivation are healthy, disease-free and insect-free coated seeds;

[0010] S40: burying the seedlings in the sowing matrix of the seedling tray and covering with 2 mm thick fine soil;

[0011] S50: selecting a greenhouse with good light transmittance and good heat preservation and moisture retention effect for seedling cultivation, placing the seedling tray in the greenhouse; watering and fertilizing during the seedling cultivation period; the temperature of the greenhouse is set at 25-30° C., and the fresh and dry weight of the roots, total root length, total root surface area and total root volume of the tobacco blanket seedlings are significantly increased;

[0012] S60: Leaf cutting was performed twice during the seedling raising process to improve the root coiling ability of tobacco blanket seedlings;

[0013] S70: Regularly check the seedling situation and spray preventive agents;

[0014] S80: When the seedlings grow into strong seedlings, the tobacco blanket seedlings are grown;

[0015] S90: Stopping the water supply 7-10 days before transplanting the tobacco blanket seedlings to enhance the stress resistance of the tobacco blanket seedlings.

[0016] On the basis of the above technical solution, the seedling raising method of a tobacco blanket seedling of the present invention can also be improved as follows:

[0017] The seedling tray adopts one of the types of no-space and half-space, and has a length of 58 cm, a width of 28 cm, and a height of 2.5 cm.

[0018] Furthermore, the sowing matrix is ​​sterilized at high temperature before use; the sowing matrix is ​​a mixed matrix of conventional seedling matrix and natural soil, and the mass ratio thereof is conventional seedling matrix: natural soil = 70%: 30%.

[0019] Furthermore, the conventional seedling medium is a mixture of peat, vermiculite and perlite, and the mass ratio thereof is peat: vermiculite: perlite = 70%:15%:15%.

[0020] Furthermore, the pH of the natural soil is 5.56, and the natural soil contains organic matter, alkaline-hydrolyzed nitrogen, available phosphorus and fast-acting potassium, wherein the organic matter is 1.66 g / kg, and the alkaline-hydrolyzed nitrogen, available phosphorus and fast-acting potassium are 52.69, 10.6 and 105.25 mg / kg, respectively.

[0021] Furthermore, the seedlings are buried in the sowing matrix of the seedling tray, and the sowing density is 128 plants / tray, which can greatly improve the root binding force of the tobacco blanket seedlings. The seedlings in the seedling tray are arranged in a horizontal and vertical number of 16*8, and each row of the seedling tray includes 16 plants in the horizontal direction, and the spacing between plants is 3.6cm; each column of the seedling tray includes 8 plants in the vertical direction, and the spacing between plants is 3.5cm, that is, the size of a seedling block is 3.5*3.6.

[0022] Furthermore, during the seedling raising period, water is poured every 2-3 days to keep the moisture of the soil surface above 80%; within 0-15 days of the tobacco blanket seedling raising, the volume moisture content of the sowing matrix is ​​25%-35%, which is more beneficial to the overall growth of the tobacco seedlings; within 15-30 days of the tobacco blanket seedling raising, the volume moisture content of the sowing matrix is ​​below 25%, which does not affect the growth of the plants and promotes the growth of the root system;

[0023] During the seedling raising process, fertilizers are applied when the tobacco seedlings have 4 leaves and one heart and when the seedlings are 15 days old. The fertilizer applied is a compound fertilizer, which contains 15% N, 15% P2O5 and 15% K2O. The fertilizer amount corresponding to the seedling raising tray is 15g, which is beneficial to the rapid development of the tobacco blanket seedlings and to improving the quality and transplantability of the tobacco seedlings. The fertilizer can be 30mg / L NAA or 20mg / L to 30mg / L niclorac.

[0024] The specific steps of fertilization are as follows: dissolve 15g of fertilizer in 1L of distilled water and spray on the leaves, spray 500mL each time, and spray with clean water once after fertilization;

[0025] Furthermore, the first leaf cutting is performed when the tobacco seedlings are just sealed in the tray, and the second leaf cutting is performed 14 days after the tray is sealed;

[0026] When cutting the leaves, there is no visible water on the tobacco leaves, and the cutting area is 1 / 2 of the tobacco leaves, which significantly improves the root binding force of the tobacco blanket seedlings.

[0027] Furthermore, the preventive agent is one of Bordeaux mixture and Zineb; the main diseases in the seedling stage are anthracnose, damping-off disease and the like.

[0028] Furthermore, the strong seedlings are seedlings with an age of 55-60 days, 4-6 true leaves, a seedling stem height of 7-10 cm, a seedling stem thickness of 0.6-1 cm, strong flexibility, light green or green leaves, thick leaves, thick main roots, well-developed lateral roots, fresh root systems, and no symptoms of disease and insect pest infection; the tobacco seedlings grow uniformly, are uniform in size, have strong growth potential, have a one-time seedling rate of more than 95%, and the strong seedlings account for more than 95% of the seedlings.

[0029] Compared with the prior art, the tobacco blanket seedling raising method provided by the present invention has the following beneficial effects:

[0030] 1. The root coiling force of tobacco blanket seedlings was extremely significantly positively correlated with the number of primary lateral roots, secondary lateral root density, total root length, total root surface area and total root volume (p<0.01), and significantly positively correlated with root fresh weight and average root diameter (p<0.05); it was significantly positively correlated with aboveground dry weight and total dry weight (p<0.1). A good root system is a key factor in improving the root coiling force and obtaining high-quality blanket seedlings suitable for mechanization; the seedling density is 128 plants / tray, the leaf cutting area does not exceed 1 / 2, the number of leaf cuttings is 2 to 3 times, the temperature is controlled at 25℃~30℃, about 15g of compound fertilizer is sprayed on each tray, and 30mg / L NAA or 20mg / L~30mg / L oxadiazole is sprayed on the leaves during the 4-leaf one-heart period. Through the above measures, high-quality tobacco blanket seedlings can be cultivated.

[0031] 2. With the decrease of seedling density, the dry and fresh weight and root indexes of tobacco blanket seedlings showed an increasing trend, but the root binding force under the treatment of 50 plants / tray was significantly lower than that of 128 plants / tray and 72 plants / tray. In order to reduce the difficulty of transplanting, 128 plants / tray is appropriate in actual production; the dry and fresh weight of the aboveground part and the root system showed an increasing trend within a certain period of time with the increase of nutrient concentration, but this trend gradually decreased with the increase of treatment time; the nutrient treatment of 15g / tray will promote the reduction of tobacco seedling stem height, the thickening of stem circumference, the increase of root indexes such as total root length, and the significant increase of root binding force.

[0032] 3. During the tobacco blanket seedling cultivation process, the leaf cutting area is 1 / 4 or 1 / 2, and the number of leaf cutting is 2 to 3 times. This can significantly promote the material accumulation, stem height, stem girth and root system indicators of the tobacco blanket seedlings, and relatively good quality tobacco blanket seedlings can be obtained. Too many leaf cutting times or too large a degree of leaf cutting are not conducive to the growth of the blanket seedlings.

[0033] 4. In the early stage of tobacco blanket seedling cultivation (0-15 days), a substrate volume moisture content between 25% and 35% is more beneficial to the overall growth of tobacco seedlings, while in the later stage (15-30 days), attention should be paid to proper water control. A substrate volume moisture content of 25% can ensure that it does not affect plant growth while promoting root growth; a seedling cultivation temperature between 25℃ and 30℃ can significantly promote the material accumulation of tobacco blanket seedlings and the improvement of root phenotype. Under this condition, the root system of tobacco blanket seedlings is best.

[0034] 5. With the increase of NAA and chloranil concentration, the aboveground and root dry and fresh weight of tobacco blanket seedlings showed a trend of increasing first and then decreasing. Foliar spraying of 30 mg / L NAA at the 4-leaf and 1-heart stage can significantly improve the material accumulation and root index of tobacco blanket seedlings, and significantly improve the root entanglement of blanket seedlings. The optimal concentration of spraying chloranil is 20 mg / L-30 mg / L. Under this condition, the quality and root entanglement of tobacco blanket seedlings are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0036] Figure 1 The present invention is an operation flow chart of a method for raising tobacco blanket seedlings;

[0037] Figure 2 This is a comparison chart of the effect of density on the accumulation of substances in tobacco blanket seedlings;

[0038] Figure 3 This is a comparison chart of the effect of density on the stem height and stem girth of tobacco blanket seedlings;

[0039] Figure 4 This is a comparison chart of the effect of density on the root phenotype of tobacco blanket seedlings;

[0040] Figure 5 This is a comparison chart of the effect of density on the root entanglement of tobacco blanket seedlings;

[0041] Figure 6 This is a comparison chart of the effects of nutrients on the accumulation of substances in tobacco blanket seedlings;

[0042] Figure 7 This is a comparison chart of the effects of nutrients on the stem height and stem girth of tobacco blanket seedlings;

[0043] Figure 8 This is a comparison chart of the effects of nutrients on the root phenotype of tobacco blanket seedlings;

[0044] Fig. 9 This is a comparison chart of the effect of nutrients on the root entanglement of tobacco blanket seedlings;

[0045] Fig.10 This is a comparison chart of the effect of leaf cutting area on the accumulation of substances in tobacco blanket seedlings;

[0046] Fig.11 This is a comparison chart of the effect of leaf cutting area on the stem height and stem girth of tobacco blanket seedlings;

[0047] Fig.12 This is a comparison chart of the effect of leaf cutting area on the root phenotype of tobacco blanket seedlings;

[0048] Fig.13 This is a comparison chart of the effect of leaf cutting area on the root entanglement of tobacco blanket seedlings;

[0049] Fig.14 This is a comparison chart of the effect of leaf cutting times on the accumulation of substances in tobacco blanket seedlings;

[0050] Fig.15 This is a comparison chart of the effects of leaf cutting times on the stem height and stem girth of tobacco blanket seedlings;

[0051] Fig.16 This is a comparison chart of the effects of leaf cutting times on the root phenotype of tobacco blanket seedlings;

[0052] Fig.17 This is a comparison chart of the effect of leaf cutting times on the root entanglement of tobacco blanket seedlings;

[0053] Fig.18 This is the correlation diagram between the moisture content of the matrix and the amount of water added;

[0054] Fig.19 This is a comparison chart of the effect of substrate moisture content on the accumulation of substances in tobacco blanket seedlings;

[0055] Fig. 20 This is a comparison chart of the effect of substrate moisture content on the stem height and stem girth of tobacco blanket seedlings;

[0056] Fig.21 This is a comparison chart of the effect of substrate moisture content on the root phenotype of tobacco blanket seedlings;

[0057] Fig. 22 This is a comparison chart of the effect of substrate moisture content on the root entanglement of tobacco blanket seedlings;

[0058] Fig.23 This is a comparison chart of the effect of temperature on the accumulation of substances in tobacco blanket seedlings;

[0059] Fig.24 This is a comparison chart of the effect of temperature on the stem height and stem girth of tobacco blanket seedlings;

[0060] Fig.25 This is a comparison chart of the effect of temperature on the root phenotype of tobacco blanket seedlings;

[0061] Fig.26 This is a comparison chart of the effect of temperature on the root entanglement of tobacco blanket seedlings;

[0062] Fig. 27 This is a comparison of the effects of NAA on the accumulation of substances in tobacco blanket seedlings;

[0063] Fig.28 This is a comparison chart of the effects of NAA on the stem height and stem girth of tobacco blanket seedlings;

[0064] Fig.29 This is a comparison of the effects of NAA on the root phenotype of tobacco blanket seedlings;

[0065] Fig.30 This is a comparison chart of the effect of NAA on the root entanglement of tobacco blanket seedlings;

[0066] Fig.31This is a comparison chart of the effects of uniconazole on the accumulation of substances in tobacco blanket seedlings;

[0067] Fig.32 This is a comparison chart of the effects of uniclobutanil on the stem height and stem girth of tobacco blanket seedlings;

[0068] Fig.33 This is a comparison chart of the effects of uniconazole on the root phenotype of tobacco blanket seedlings;

[0069] Fig.34 This is a comparison chart of the effect of closaconazole on the root entanglement of tobacco blanket seedlings;

[0070] Fig.35 Schematic diagram of comprehensive evaluation index in the embodiment;

[0071] Fig.36 This is a side view of the blanket seedlings when they are growing strong;

[0072] Fig.37 This is a schematic diagram of the bottom of the blanket seedlings. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0074] Example: Determine the influence of different factors on tobacco seedling quality through multiple groups of experiments

[0075] like Figure 1 As shown, the tobacco seedlings are cultivated by the transplanting method: the coated seeds are evenly sown in the seedling tray, watered regularly, and after the tobacco seedlings reach the small cross stage, the strong seedlings with uniform growth are selected and transplanted into the seedling tray. The transplanting matrix is ​​a mixed matrix (the mass ratio is conventional seedling matrix: natural soil = 70%: 30%), the mass ratio of the conventional seedling matrix is ​​peat: vermiculite: perlite = 70%: 15%: 15%, the pH of the natural soil is 5.56, the organic matter is 1.66g / kg, and the alkaline nitrogen, available phosphorus and available potassium are 52.69, 10.6 and 105.25mg / kg respectively.

[0076] Take the tobacco seedlings out of the seedling tray (keeping the root system intact), clean the substrate with tap water, and then use filter paper to absorb the water attached to the tobacco seedlings.

[0077] The stem height of tobacco seedlings (the length from the stem base to the growing point) was measured using a ruler. The stem diameter was measured using a vernier caliper. The fresh weight of the aboveground part and the root system were weighed separately using an electronic balance.

[0078] Place the tobacco seedlings in a 105°C oven for 20 minutes, then adjust the temperature to 75°C and dry them to constant weight. Use an electronic balance to weigh the dry weight of the aboveground part and the root system.

[0079] The number of primary lateral roots was counted by visual inspection, and other root indexes were measured using LA1600+ root scanner. The roots of tobacco seedlings were cut, cleaned and placed in a root scanner for scanning. The image parameters were analyzed using Win RHizo2003b software to obtain the total root length, average root diameter, total root surface area and total root volume.

[0080] On the 30th day of the treatment, randomly cut out 10×15 cm blankets from each treatment, fix their long ends on the root intertwining force measuring device, and pull them with a spring scale hook. The reading displayed on the spring scale when the blanket breaks is the root intertwining force.

[0081] 1. Determine the influence of density and nutrients on tobacco seedling quality

[0082] Multiple control groups were designed: three levels of density treatment were set, namely D1 (128 plants per tray, with a plant spacing of 3.5 cm), D2 (72 plants per tray, with a plant spacing of 4.5 cm), and D3 (50 plants per tray, with a plant spacing of 5.5 cm); three levels of nutrient treatment were set, namely F1 (5 g / tray), F2 (10 g / tray) and F3 (15 g / tray), the transplanting specifications were 128 plants per tray (8 rows × 16 columns), with a plant spacing of 3.5 cm, the treatment began at the 4-leaf one-heart stage, the fertilizer applied was compound fertilizer (N 15%, P2O5 15%, K2O 15%), the application method was to dissolve the fertilizer in 1L of distilled water, spray the leaves once at the beginning of the treatment and 15 days after the treatment, 500 mL each time, and spray clean water once after fertilization. Other management methods remained the same during the treatment process. Samples were taken every 5 days after the start of treatment, with 3 biological replicates each time, for a total of 30 days of treatment.

[0083] in conclusion:

[0084] from Figure 2-5 It can be seen that with the decrease of seedling density, the aboveground and root dry and fresh weight of tobacco blanket seedlings showed an increasing trend, the stem height decreased, the stem girth increased, the root morphological indicators were significantly improved, but the root entanglement force decreased significantly.

[0085] from Figure 6-9 It can be seen that with the increase of nutrient concentration, the aboveground and root dry and fresh weight of tobacco seedlings showed an increasing trend within a certain period of time, but with the increase of treatment time, this trend gradually decreased; 15g / tray compound fertilizer spraying treatment will reduce the stem height of tobacco seedlings, increase the stem circumference, and make the overall plant type of tobacco seedlings shorter and stronger; the total root length, total root surface area and total root volume all showed an increasing trend with the increase of nutrient concentration, and a better root system significantly increased its root binding force. In general, applying 15g of fertilizer per tray of tobacco seedlings can obtain higher quality tobacco blanket seedlings.

[0086] 2. Effect of leaf cutting on the growth of tobacco blanket seedlings

[0087] The transplanting specification was 128 plants per tray (8 rows × 16 columns), with a plant spacing of 3.5 cm. The experimental design was divided into two treatments, namely, leaf cutting area treatment and leaf cutting frequency treatment. The leaf cutting area treatment was set at 4 levels, namely, cutting 1 / 4 leaves (CA1), cutting 1 / 2 leaves (CA2), cutting 3 / 4 leaves (CA3) and no leaf cutting (CK). Leaf cutting began when the tobacco seedlings were sealed in the tray, and was cut once every 7 days, for a total of 4 times. The leaf cutting frequency treatment was set at 5 levels, namely, cutting leaves once (CT1), cutting leaves twice (CT2), cutting leaves three times (CT3), cutting leaves four times (CT4) and no leaf cutting (CK). CT1 is to cut leaves 7 days after the seedlings are sealed, CT2 is to cut leaves 14 days after the seedlings are sealed, CT3 is to cut leaves 14 days after the seedlings are sealed, and 21 days after the seedlings are sealed, and CT4 is to cut leaves 7 days after the seedlings are sealed, 14 days after the seedlings are sealed, and 21 days after the seedlings are sealed. Each time the leaves are cut, only the two largest leaves and the old and diseased leaves at the bottom are cut. Except for the different leaf cutting during the treatment process, the other management methods are the same. The treatment lasts for 30 days in total. Samples are taken every 3 days for the leaf cutting area test, and every 5 days for the leaf cutting number test. Three biological replicates are taken each time.

[0088] in conclusion:

[0089] from Figure 9-17 It can be seen that during the cultivation of tobacco blanket seedlings, keeping the leaf cutting area at 1 / 4 or 1 / 2 can promote the accumulation of substances, increase the stem height, stem girth and root system indicators of tobacco blanket seedlings, while excessive leaf cutting is not good for blanket seedlings. Leaf cutting area of ​​1 / 2 can significantly improve the root entanglement of tobacco blanket seedlings. During the cultivation of tobacco blanket seedlings, leaf cutting 2 to 3 times can promote the accumulation of substances, increase the stem height, stem girth and root system indicators of tobacco blanket seedlings. If the number of leaf cutting is too many, the growth of blanket seedlings will be inhibited. Leaf cutting twice can significantly improve the root entanglement of tobacco blanket seedlings.

[0090] 3. Effects of substrate moisture content and temperature on the growth of tobacco blanket seedlings

[0091] The specification of transplanting was 128 plants per tray (8 rows × 16 columns), with a plant spacing of 3.5 cm. The treatment of substrate moisture content was set at three levels, namely W1 (substrate moisture content 25% ± 3%), W2 (substrate moisture content 35% ± 3%), and W3 (substrate moisture content 45% ± 3%), and the treatment began at the big cross stage of tobacco seedlings; the temperature treatment was set at five levels, namely T15 (15℃), T20 (20℃), T25 (25℃), T30 (30℃), and T35 (35℃), and the treatment began at the big cross stage of tobacco seedlings. The day and night temperatures of the light incubator were set at the treatment temperature and 15℃, the relative humidity was 70%, and the light and dark cycle was 14h / 10h. The rest of the management methods remained the same during the treatment process. The treatment lasted for 30 days in total, and samples were taken every 5 days after the start of the treatment, with 3 biological replicates for each sampling.

[0092] Weigh 500g of dried substrate, water thoroughly and measure the maximum moisture content of the substrate, then dry the substrate in the shade at room temperature, and measure the moisture content of the substrate with a moisture content rapid tester every 12 hours until the moisture content no longer changes. At this time, add 50ml of water to the substrate and mix well, collect moisture content data, and repeat the steps until the moisture content reaches the upper limit of the moisture content of the substrate, and deduce the correlation between the amount of water added and the moisture content of the substrate.

[0093] in conclusion:

[0094] from Figure 18-26 It can be seen that in order to cultivate high-quality blanket seedlings that meet the requirements of mechanized transplanting, the substrate moisture content should be between 25% and 35%. In the early stage (0-15 days), when the substrate moisture content is 35%, it is more beneficial to the overall growth of tobacco seedlings. Under long-term (15-30 days) conditions, attention should be paid to proper water control. The substrate moisture content is more suitable at 25%, which can ensure that it does not affect the growth of the plant while promoting the growth of the root system. The size of the root system is a key factor in improving the root system's ability to coil and obtain high-quality blanket seedlings suitable for mechanization.

[0095] In order to cultivate high-quality blanket seedlings that meet the requirements of mechanized transplanting, the seedling temperature should be between 25℃ and 30℃. Too high or too low temperature will inhibit the growth of tobacco seedlings, and the inhibition of root growth will reduce the root coiling ability of tobacco blanket seedlings.

[0096] 4. Effects of chemical control on the growth of tobacco blanket seedlings

[0097] The transplanting specification was 128 plants per tray (8 rows × 16 columns), with a plant spacing of 3.5 cm. Two experimental treatments were set up, namely NAA regulation experiment and uniconazole regulation experiment. Among them, NAA regulation experiment set 4 levels, namely CK (spraying water), N20 (20 mg / L), N30 (30 mg / L) and N40 (40 mg / L), uniconazole regulation experiment set 4 levels, namely CK (spraying water), U20 (20 mg / L), U30 (30 mg / L) and U40 (40 mg / L). Treatment began when the tobacco seedlings had 4 leaves and 1 heart, and sprayed once at the beginning of treatment and 15 days after treatment, until the leaf surface was covered with droplets and was about to fall. The management method was consistent during the treatment process. Samples were taken every 5 days after the start of treatment, and 3 biological replicates were taken each time, and the treatment was 30 days in total.

[0098] in conclusion:

[0099] from Figure 27-34 It can be seen that the optimum concentration of NAA spraying in the four-leaf and one-heart period is 30 mg / L, under which the quality and root entanglement of tobacco blanket seedlings are significantly improved; foliar spraying of 20 mg / L to 30 mg / L of closaconazole in the four-leaf and one-heart period can significantly improve the material accumulation and root indexes of tobacco blanket seedlings, and significantly improve the root entanglement of blanket seedlings. If the concentration exceeds 40 mg / L, it will inhibit the improvement of the aboveground and root indexes of tobacco seedlings.

[0100] 5. Correlation between root binding capacity and phenotypic indicators and construction of seedling index

[0101] according to Figure 2-Figure 34 The obtained data were analyzed according to the fuzzy comprehensive evaluation method, and all the measured tobacco blanket seedling phenotypes were organized into a parameter matrix W (the matrix has m rows and n columns, where m is the number of samples and n is the number of indicators). The indicator evaluation matrix M was calculated according to the membership function and critical value of each indicator of the tobacco seedling, and the indicator weight coefficient O was calculated using the entropy weight method. The indicator evaluation matrix M and the weight coefficient matrix O were multiplied to obtain the comprehensive evaluation index. Figure 36-37 Shown is a schematic diagram of the side and bottom of the blanket seedlings when they are strong.

[0102] The index data were analyzed by principal component analysis to obtain the principal components with large differences and the indexes with large contribution rates in each principal component. The three indexes with the largest contribution rates in each principal component were randomly selected and combined to preliminarily establish the tobacco blanket seedling index model. The most suitable seedling index model was screened through correlation analysis with the comprehensive evaluation index.

[0103] Based on the comprehensive evaluation index of samples, cluster analysis was conducted on the optimal seedling index to clarify the numerical range of the seedling index of tobacco blanket seedlings of different quality levels.

[0104] in conclusion:

[0105] 1. Correlation between root binding capacity and phenotype

[0106] As can be seen from Table 1, the root entanglement force of tobacco blanket seedlings is extremely significantly positively correlated with stem diameter, primary lateral root number, secondary lateral root density, total root length, total root surface area and total root volume (p<0.01), and is significantly positively correlated with stem height, root fresh weight and average root diameter (p<0.05); and is significantly positively correlated with aboveground dry weight and total dry weight (p<0.1). Therefore, increasing the size of the root system is conducive to increasing the root entanglement force.

[0107] Table 1 Correlation between root phenotype and root binding capacity of tobacco blanket seedlings

[0108]

[0109]

[0110] 2. Index membership function type and critical value

[0111] The membership functions and parameters of tobacco seedling indicators are shown in Table 2. Among them, the deviation of stem height, aboveground fresh weight and aboveground dry weight from a certain range will lead to the deterioration of its quality, which is suitable for parabolic membership function; stem thickness, aboveground dry weight and total dry weight are positively correlated with tobacco seedling quality, and those greater than a certain value are considered strong seedlings, which conforms to the characteristics of positive S-type membership function; root fresh weight, primary lateral root number, secondary lateral root density, total root length, average root diameter, total root volume and root coiling force are positively correlated with tobacco seedling quality, and there is no obvious upper and lower limit range of values, which conforms to the linear membership function.

[0112] Table 2 Indicator membership function and critical value

[0113]

[0114] 3. Index weight coefficient

[0115] It can be seen from Table 3 that the weights of tobacco blanket seedling indicators range from 0.0137 to 0.1450, among which the weight coefficient of stem diameter is the smallest, which is 0.0137; the weight coefficient of total fresh weight is the largest, which is 0.1450.

[0116] Table 3 Index weight coefficient

[0117]

[0118] 4. Index weight coefficient

[0119] like Fig.35As shown, the comprehensive evaluation index of the seedling stage is calculated and the values ​​are arranged from large to small. The comprehensive evaluation index of tobacco seedling quality ranges from 0.1661 to 0.6635. The curve has a large span, which can comprehensively summarize the quality of tobacco seedlings and accurately evaluate the quality of tobacco seedlings.

[0120] 5. Key indicator screening and seedling index construction

[0121] As shown in Table 4, the 15 tobacco seedling single indexes were divided into three principal components, with a cumulative contribution rate of 79.37%, of which the variance contribution rates of PC1, PC2 and PC3 were 46.97%, 16.63% and 15.77% respectively. The three indexes with the largest contribution rate were selected from each principal component (Table 5), of which PC1 included total root length, total root surface area and root coiling force; PC2 included stem height, aboveground fresh weight and total fresh weight; PC3 included aboveground dry weight, secondary lateral root density and average root diameter. The seedling index must include one or more of these three principal components to fully reflect the quality differences of tobacco blanket seedlings. In order to make the seedling index comprehensive and as simple as possible, one index was selected from each principal component for combination, and 27 seedling indexes were obtained (Table 6). Since the quality of tobacco seedlings is closely related to the accumulation of dry matter per unit stem height, the seedling index adopts the conversion method of " / stem height". The other indicators are all positive indicators, so the combination adopts the product method.

[0122] Table 4 Principal component analysis results

[0123]

[0124]

[0125] Table 5 Main indexes of principal components

[0126]

[0127] Table 6 Construction of seedling strength index

[0128]

[0129] The results of correlation analysis between seedling index and comprehensive evaluation index are shown in Table 7. It can be seen that X1, X3, X6, X10 and X12 are significantly positively correlated with the comprehensive evaluation index, and the remaining combinations are extremely significantly positively correlated with the comprehensive evaluation index. Among them, X26 (root system coiling force × total fresh weight × secondary lateral root density / stem height) has the largest correlation coefficient (0.8753), and the model is relatively optimal.

[0130] Table 7 Correlation analysis between seedling strength index and comprehensive evaluation index

[0131]

[0132] Note: "**" indicates extremely significant difference (p < 0.01), and "*" indicates significant difference (p < 0.05).

[0133] 6. Grading of tobacco seedling quality

[0134] The seedling index X26 was analyzed by cluster analysis, and the tobacco seedling quality was divided into three levels (Table 8, which were the best seedling level (≥30.04), the strong seedling level (14.23-30.04) and the weak seedling level (≤14.23). The variance analysis showed that the differences among the three levels were extremely significant, which can be used as the basis for grading the quality of tobacco blanket seedlings. Combining the seedling index X26 with the tobacco seedling indicators in the seedling stage, it can be seen that when the tobacco blanket seedlings reach the optimal seedling level, the threshold of the key indicators of strong seedlings is about 3.90g total fresh weight, about 1.95 secondary lateral root density / cm, about 4.42cm stem height, and more than 17.41N root coiling force.

[0135] Table 8 Quality grades of tobacco blanket seedlings

[0136]

[0137] Note: Different capital letters indicate extremely significant differences (p<0.01).

[0138] 7. Dealing with differences in tobacco seedling quality

[0139] As can be seen from Table 9, the coefficient of variation of each treatment ranged from 13.52% to 36.23%, among which the temperature treatment, nutrient treatment and NAA treatment had a larger degree of variation. Except for the number of leaf cutting, the average seedling index of the other treatments could reach the level of strong seedlings. On the whole, the temperature treatment, nutrient treatment, NAA treatment and ethylenediaminetetracycline treatment were more valuable in subsequent research.

[0140] Table 9 Differences in quality of tobacco seedlings under different treatments

[0141]

[0142] In summary, in order to achieve high-speed and efficient mechanical transplanting. Blanket seedling cultivation is quite different from traditional seedling cultivation methods, so it has more stringent requirements on the quality of tobacco seedlings. Root coiling force is an important indicator for evaluating the comprehensive quality of tobacco blanket seedlings. It directly determines whether tobacco blanket seedlings can be used for production. During the transplanting process of tobacco blanket seedlings, it is necessary to rely on the planting arm to continuously grab each tobacco seedling and insert it into the ridge surface. This requires that the tobacco blanket seedlings have a well-developed root system, tightly coiled, and form a whole with the substrate. Otherwise, it cannot meet the planting arm's precise positioning requirements for the blanket and tobacco seedlings. The root coiling force is significantly or extremely significantly positively correlated with root indicators such as total root length, indicating that the root size plays a decisive role in the root coiling force during the cultivation of blanket seedlings. Overall, a larger root system is conducive to improving the root coiling force, and improving root indicators through certain measures is conducive to increasing the root coiling force.

[0143] Tobacco blanket seedlings should be short and strong, with well-developed and entangled root system, total fresh weight of about 3.90g, secondary lateral root density of about 1.95 roots / cm, stem height of about 4.42cm, and root entanglement force of more than 17.41N. The comprehensive evaluation index reflecting the overall quality of tobacco blanket seedlings was obtained by comprehensive fuzzy judgment method, and then the strong seedling index for tobacco blanket seedlings was obtained by principal component analysis, construction of strong seedling index, and correlation analysis: root entanglement force × total fresh weight × secondary lateral root density / stem height. Compared with the research on other tobacco strong seedling indexes, the stem height and total fresh weight of tobacco blanket seedlings were both smaller, and the root entanglement force showed a strong correlation with the root phenotype. Therefore, in actual production, strong seedling measures should be taken to improve material accumulation and root phenotype to prevent tobacco seedlings from growing too tall, so as to achieve the purpose of cultivating strong seedlings.

[0144] The root entanglement force of tobacco blanket seedlings was extremely significantly positively correlated with stem diameter, number of primary lateral roots, density of secondary lateral roots, total root length, total root surface area and total root volume (p<0.01), and significantly positively correlated with stem height, root fresh weight and average root diameter (p<0.05); it was significantly positively correlated with aboveground dry weight and total dry weight (p<0.1), indicating that increasing the size of the root system is conducive to increasing the root entanglement force.

[0145] Specifically, the principle of the present invention is: when in use, add clean water to the sowing matrix, mix well, and put it into the seedling tray; the amount of water added is the state of hand-kneading into a ball; after putting it into the tray, use a sprayer to water the sowing matrix until water seeps out from under the seedling tray; select seedling seeds, which are healthy, disease-free and insect-free coated seeds; bury the seedling seeds in the sowing matrix of the seedling tray and cover them with 2 mm thick fine soil; place the seedling tray in a greenhouse for seedling cultivation; water and fertilize during the seedling cultivation period; the temperature of the greenhouse is set at 25-30°C; cut leaves twice during the seedling cultivation process to improve the root coiling force of the tobacco blanket seedlings; regularly check the seedling cultivation situation and spray preventive agents; when the seedling seeds grow into strong seedlings, the tobacco blanket seedlings are cultivated; stop water supply 10-15 days before transplanting the tobacco blanket seedlings to enhance the stress resistance of the tobacco blanket seedlings.

Claims

1. A method for raising tobacco blanket seedlings, characterized in that: The following steps are involved: S10: Add clean water to the sowing substrate and mix well, and put it into the seedling tray; the amount of water added is enough to form a ball by hand; S20: After placing the seeds in the tray, use a sprayer to water the seeding medium sufficiently until water seeps out from under the seedling tray; S30: selecting seeds for seedling cultivation, wherein the seeds for seedling cultivation are healthy, disease-free and insect-free coated seeds; S40: burying the seedlings in the sowing matrix of the seedling tray and covering with 2 mm thick fine soil; S50: placing the seedling tray in a greenhouse to grow seedlings; watering and fertilizing during the seedling growing period; the temperature of the greenhouse is set at 25-30° C.; S60: Leaf cutting was performed twice during the seedling raising process to improve the root coiling ability of tobacco blanket seedlings; S70: Regularly check the seedling situation and spray preventive agents; S80: When the seedlings grow into strong seedlings, the tobacco blanket seedlings are grown; S90: stopping water supply 7-10 days before transplanting the tobacco blanket seedlings to enhance stress resistance of the tobacco blanket seedlings; The data of tobacco blanket seedlings under different parameters were tested and analyzed according to the fuzzy comprehensive evaluation method. All the measured tobacco blanket seedlings phenotypes were organized into a parameter matrix W. The index evaluation matrix M was calculated according to the membership function and critical value of each index of tobacco seedlings. The index weight coefficient O was calculated by the entropy weight method. The index evaluation matrix M and the weight coefficient matrix O were multiplied to get the comprehensive evaluation index. The principal component analysis was performed on the index data to obtain the principal components with large differences and the indexes with large contribution rates in each principal component. The three indexes with the largest contribution rates in each principal component were selected and randomly combined to preliminarily establish the tobacco blanket seedlings phenotype. Seedling strength index model: root coiling force × total fresh weight × secondary lateral root density / stem height; the most suitable seedling strength index model was screened through correlation analysis with the comprehensive evaluation index; based on the comprehensive evaluation index of the samples, cluster analysis was performed on the optimal seedling strength index to clarify the numerical range of the seedling strength index of tobacco blanket seedlings of different quality levels; compared with the research on other tobacco seedling strength indicators, the stem height and total fresh weight in the threshold of tobacco blanket seedlings were both smaller, and the root coiling force showed a strong correlation with the root phenotype. Through seedling strength measures, material accumulation and root phenotype were improved to prevent tobacco seedlings from growing too tall, so as to achieve the purpose of cultivating strong seedlings; The root entanglement force of tobacco blanket seedlings was extremely significantly positively correlated with stem diameter, number of primary lateral roots, density of secondary lateral roots, total root length, total root surface area and total root volume (p < 0.01), and significantly positively correlated with stem height, root fresh weight and average root diameter (p < 0.05); it was significantly positively correlated with aboveground dry weight and total dry weight (p < 0.1), indicating that increasing the size of the root system is conducive to increasing the root entanglement force.

2. The method for raising tobacco blanket seedlings according to claim 1, characterized in that: The seedling tray adopts one of no-space and half-space, and has a length of 58 cm, a width of 28 cm, and a height of 2.5 cm.

3. The method for raising tobacco blanket seedlings according to claim 2, characterized in that: The sowing matrix is ​​sterilized at high temperature before use; the sowing matrix is ​​a mixed matrix of conventional seedling raising matrix and natural soil, and the mass ratio thereof is conventional seedling raising matrix: natural soil = 70%: 30%.

4. The method for raising tobacco blanket seedlings according to claim 3, characterized in that: The conventional seedling medium is a mixture of peat, vermiculite and perlite, and the mass ratio thereof is peat: vermiculite: perlite=70%:15%:15%.

5. The method for raising tobacco blanket seedlings according to claim 4, characterized in that: The pH of the natural soil is 5.

56. The natural soil contains organic matter, alkaline-hydrolyzed nitrogen, available phosphorus and fast-acting potassium, wherein the organic matter is 1.66 g / kg, and the alkaline-hydrolyzed nitrogen, available phosphorus and fast-acting potassium are 52.69, 10.6 and 105.25 mg / kg respectively.

6. The method for raising tobacco blanket seedlings according to claim 5, characterized in that: The seedling seeds are buried in the sowing matrix of the seedling tray, and the sowing density is 128 plants / tray.

7. The method for raising tobacco blanket seedlings according to claim 6, characterized in that: During the seedling raising period, water is poured every 2-3 days to keep the moisture of the soil surface above 80%; within 0-15 days of the tobacco blanket seedling raising, the volume moisture content of the sowing matrix is ​​25%-35%; within 15-30 days of the tobacco blanket seedling raising, the volume moisture content of the sowing matrix is ​​below 25%; During the seedling raising process, fertilizers were applied when the tobacco seedlings had 4 leaves and one heart and when the seedlings were 15 days old. The fertilizer applied was compound fertilizer containing 15% N, 15% P2O5 and 15% K2O. The fertilizer amount corresponding to the seedling raising tray was 15g. The specific steps of fertilization are: dissolve 15g of fertilizer in 1L of distilled water and spray it on the leaves, spraying 500mL each time, and spraying with clean water once after fertilization.

8. The method for raising tobacco blanket seedlings according to claim 7, characterized in that: The first leaf cutting is done when the seedlings are just sealed in the tray, and the second leaf cutting is done 14 days after the tray is sealed. When cutting the leaves, there should be no visible water on the leaves, and the cutting area should be 1 / 2 of the leaves.

9. The method for raising tobacco blanket seedlings according to claim 8, characterized in that: The preventive agent is one of Bordeaux mixture and Zineb.

10. The method for raising tobacco blanket seedlings according to claim 9, characterized in that: The strong seedlings are seedlings with a seedling age of 55-60 days, 4-6 true leaves, a seedling stem height of 7-10 cm, and a seedling stem thickness of 0.6-1 cm.

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