A method for determining the tobacco plant type based on the ratio of leaf area index

Abstract

The present invention discloses a method for determining the tobacco plant type based on the leaf area index ratio, belonging to the technical field of agricultural production. The steps are as follows: Set up an interaction experiment of nitrogen fertilizer and planting density for tobacco to obtain several experimental groups with unique and different nitrogen fertilizer gradients and planting densities; According to the preset stage time, obtain the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group; Initially confirm the tobacco plant type, assign a value to the plant type, and record the upper leaf area index ratio accordingly; Construct a tobacco plant type confirmation model based on the leaf area index ratio; Obtain the first critical leaf area index ratio and the second critical leaf area index ratio; Use the tobacco plant type confirmation model and the critical leaf area index ratio to confirm the tobacco plant type of any arbitrarily obtained tobacco. The present invention solves the problems that the existing tobacco plant type confirmation methods lack the analysis of the dynamic growth process of tobacco and are difficult to perform quantitative analysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural production, and particularly relates to a method for determining the tobacco plant type based on the leaf area index ratio. Background Art

[0002] The plant type is crucial for the quality and yield of tobacco leaves. There are significant differences in the physical characteristics, tissue structure, physiological metabolism, and nutrient accumulation of tobacco leaves with different plant types. For the regulation of the tobacco plant type, it is often improved according to breeding and cultivation management, and the advantageous traits of high quality and high yield are comprehensively coordinated to form an advantageous plant type structure. Existing research believes that the advantageous plant type structure of tobacco should be "sufficient sunlight for the lower leaves, unfolded upper leaves, and moderate thickness of the whole plant's leaves", focusing on "narrowing the quality differences between different parts of the leaves" to achieve "consistent color at the leaf tip and leaf base, and consistent color on the leaf back and leaf surface", and further proposes the concept of "medium-sized tobacco plants", that is, the tobacco plants are of medium size, with neither over-vigorous nor over-weak growth, and a group appearance with coordinated yield and quality. In the tobacco-growing area of Xuchang, Henan, the "three consistencies" tobacco appearance standard has also been proposed, that is, the tobacco seedlings are of the same size, the tobacco plants are of the same height, and the tobacco leaves at the same position are mature at the same time. Based on the combination of production experience, existing research has summarized the field appearance of high-quality tobacco: the plant type is waist-drum-shaped or cylindrical. In Zhucheng, Shandong, it is proposed that the tobacco appearance is waist-drum-shaped in the early stage and cylindrical in the later stage, with a plant height of 100 - 120 cm, about 20 effective leaves per single plant, the maximum leaf length not exceeding 75 cm, and the single leaf weight of the middle leaves being 9 - 12 g. In Shiyan, Hubei, it is proposed that after topping, the plant height is 100 - 120 cm, the stem circumference is 8 - 10 cm, the internode distance is 4 - 5 cm, the lower leaves are 50 - 60 cm long and 22 - 28 cm wide, the middle leaves are 55 - 70 cm long and 25 - 30 cm wide, and the upper leaves are 55 - 65 cm long and 20 - 28 cm wide. In recent years, research on the classification indicators of tobacco plant types has been carried out, and a semi-quantitative method has been used to conduct characteristic research on the relationship between tobacco plant type characteristics and yield and quality, and the relationship between tobacco plant type and yield and quality has been initially clarified. However, the existing research on the determination of tobacco plant types is often empirical, and there is no in-depth discussion on the dynamic growth process of tobacco plant types, making it difficult to conduct quantitative analysis on plant types. Summary of the Invention

[0003] In view of the above deficiencies in the prior art, the present invention provides a method for determining the tobacco plant type based on the leaf area index ratio. By obtaining the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of tobacco under different growth conditions, the tobacco plant type is initially confirmed, a tobacco plant type confirmation model is constructed, the critical leaf area index ratio is calculated, and the confirmation of the tobacco plant type for any obtained tobacco is realized, solving the problems that the existing methods for confirming tobacco plant types lack analysis of the dynamic growth process of tobacco and are difficult to conduct quantitative analysis.

[0004] To achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0005] A method for determining the tobacco plant type based on the leaf area index ratio provided by the present invention includes the following steps:

[0006] S1. Set up an interaction experiment of nitrogen fertilizer and planting density for tobacco to obtain several experimental groups with unique and different nitrogen fertilizer gradients and planting densities.

[0007] S2. According to the preset stage time, obtain the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group.

[0008] S3. Based on the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group, obtain a preliminarily confirmed tobacco plant type.

[0009] S4. Based on the preliminarily confirmed tobacco plant type, assign values to the plant types of each selected tobacco in each experimental group at each growth and development stage, record the upper leaf area index ratio correspondingly, and construct a tobacco plant type confirmation model based on the leaf area index ratio.

[0010] S5. Based on the tobacco plant type assignment results and the corresponding upper leaf area index ratios, obtain the first critical leaf area index ratio and the second critical leaf area index ratio through the tobacco plant type confirmation model.

[0011] S6. Based on the first critical leaf area index ratio and the second critical leaf area index ratio, use the tobacco plant type confirmation model to confirm the tobacco plant type of any arbitrarily obtained tobacco.

[0012] The beneficial effects of the present invention are as follows: A method for determining the tobacco plant type based on the leaf area index ratio provided by the present invention provides different growth and development conditions for tobacco by setting the interaction experiment of nitrogen fertilizer and planting density of tobacco, and obtains the selected tobacco grown under different growth and development conditions; the present invention respectively obtains the upper leaf area index ratio, middle leaf area index ratio and lower leaf area index ratio of the selected tobacco at different times during the growth and development stage of tobacco, fully considering the dynamic change process during the growth and development stage of tobacco, and enriching the tobacco data basis for quantifying the confirmation of tobacco plant type; according to the leaf area index ratio of each part of tobacco, the present invention preliminarily confirms the dividable results of tobacco plant type, clarifies the critical leaf area index ratio between different tobacco plant types, makes the conditions for dividing tobacco plant type clear, and improves the efficiency of quantifying and determining tobacco plant type; the present invention constructs a tobacco plant type confirmation model based on the leaf area index ratio, and realizes the rapid and accurate confirmation of the plant type of any tobacco through the first critical leaf area index ratio and the second critical leaf area index ratio; the present invention is applicable to the confirmation of the plant type after topping of tobacco, and can also provide guarantee for cultivating high-quality tobacco and comprehensively coordinating the superior traits of high quality and high yield of tobacco.

[0013] Further, in the interaction experiment of nitrogen fertilizer and planting density of tobacco in S1, both the nitrogen fertilizer gradient and the planting density level are not less than 2.

[0014] The beneficial effect of adopting the above further scheme is that: in the interaction experiment of nitrogen fertilizer and planting density of tobacco of the present invention, requirements are put forward for the nitrogen fertilizer gradient and the planting density level, and tobacco samples under different growth environments are fully provided.

[0015] Further, S2 includes the following steps:

[0016] S21. According to the preset stage time, in the first growth and development stage, the second growth and development stage and the third growth and development stage respectively, several selected tobaccos in each experimental group are divided into parts, and the upper leaves, middle leaves and lower leaves of each tobacco are determined, wherein the lower leaves are the 1st to 6th tobacco leaves from the root to the top of the tobacco, the middle leaves are the 7th to 12th tobacco leaves from the root to the top of the tobacco, and the upper leaves are the 13th to 18th tobacco leaves from the root to the top of the tobacco;

[0017] S22. Measure the leaf length and leaf width of the upper leaves, middle leaves and lower leaves of each selected tobacco in each experimental group respectively to obtain the leaf area of each leaf position;

[0018] The calculation expression of the leaf area of each leaf position is as follows:

[0019] s leaf =l×w×α area

[0020] where sleaf S represents the leaf area of tobacco leaves, l represents the leaf length of tobacco leaves, w represents the leaf width of tobacco leaves, and α area represents the tobacco leaf area coefficient, where the tobacco leaf area coefficient is 0.6345;

[0021] S23. Calculate the upper leaf area index, middle leaf area index, and lower leaf area index of each selected tobacco in each experimental group according to the leaf areas of each leaf position;

[0022] The calculation expressions for the upper leaf area index, middle leaf area index, and lower leaf area index of the above-mentioned tobacco are as follows:

[0023]

[0024] Among them, represents the upper leaf area index, upi represents the i-th upper leaf, represents the area of the i-th upper leaf, and n p represents the number of tobacco plants per unit land area, and U la represents the unit land area, represents the middle leaf area index, midi represents the i-th middle leaf, represents the area of the i-th middle leaf, represents the lower leaf area index, boti represents the i-th lower leaf, represents the area of the i-th lower leaf;

[0025] S24. Calculate the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group according to the upper leaf area index, middle leaf area index, and lower leaf area index of each tobacco;

[0026] The calculation expressions for the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio are as follows:

[0027]

[0028] Among them, θ up represents the upper leaf area index ratio, θ mid represents the middle leaf area index ratio, θ bot represents the lower leaf area index ratio.

[0029] The beneficial effects of adopting the above further solution are as follows: In different growth and development stages of tobacco, namely the first growth and development stage, the second growth and development stage, and the third growth and development stage, the tobacco selected is divided into parts, and the leaf area index and the ratio of leaf area index of each part are obtained by calculating the leaf area of the upper leaves, middle leaves, and lower leaves, providing a data basis for the leaf area index ratio for preliminarily confirming the tobacco plant type.

[0030] Further, the preliminary confirmation of the tobacco plant type in S3 includes the first plant type, the second plant type, and the third plant type;

[0031] For the first plant type, the ratio of the leaf area index of the lower leaves is greater than the ratio of the leaf area index of the upper leaves and the ratio of the leaf area index of the middle leaves; for the second plant type, the ratio of the leaf area index of the middle leaves is greater than the ratio of the leaf area index of the upper leaves and the ratio of the leaf area index of the lower leaves; for the third plant type, the ratio of the leaf area index of the upper leaves is greater than the ratio of the leaf area index of the middle leaves and the ratio of the leaf area index of the lower leaves.

[0032] The beneficial effects of adopting the above further solution are as follows: The present invention divides the tobacco plant type according to the ratio index of the leaf area index of tobacco, and the first plant type, the second plant type, and the third plant type effectively determine the plant type structure of tobacco, providing a plant type division basis for quantitatively determining the plant type of tobacco.

[0033] Further, S4 includes the following steps:

[0034] S41: Respectively in the first growth and development stage, the second growth and development stage, and the third growth and development stage of tobacco, when the selected tobacco in each experimental group is of the first plant type, then assign a value of 1 to the selected tobacco and record the ratio of the leaf area index of its upper leaves;

[0035] S42: Respectively in the first growth and development stage, the second growth and development stage, and the third growth and development stage of tobacco, when the selected tobacco in each experimental group is of the second plant type, then assign a value of 2 to the selected tobacco and record the ratio of the leaf area index of its upper leaves; <<

[0036] S43: Respectively in the first growth and development stage, the second growth and development stage, and the third growth and development stage of tobacco, when the selected tobacco in each experimental group is of the third plant type, then assign a value of 3 to the selected tobacco and record the ratio of the leaf area index of its upper leaves;

[0037] S44: Based on the assigned values of each selected tobacco and the corresponding ratio of the leaf area index of the upper leaves, construct a tobacco plant type confirmation model based on the ratio of the leaf area index;

[0038] The calculation expression of the tobacco plant type confirmation model is as follows:

[0039] P = 6.74θ up+0.17

[0040] Among them, P represents the quantization value of the tobacco model.

[0041] The beneficial effects of adopting the above further scheme are as follows: Based on the preliminary confirmation of the tobacco plant type, the present invention assigns values to the plant types of tobacco at different growth and development stages, and respectively records the proportion of the upper leaf area index thereof, providing a basis for determining the first critical leaf area index proportion and the second critical leaf area index proportion through the upper leaf area index proportion data of sufficiently many different plant type tobaccos. The present invention provides a calculation method for the tobacco plant type confirmation model, realizing the quantization of the confirmation of the tobacco plant type, fully considering each growth and development stage of the tobacco, and also improving the efficiency and accuracy of the confirmation of the tobacco plant type.

[0042] Further, the S5 includes the following steps:

[0043] S51. Obtain the maximum value of the upper leaf area index proportion of the tobacco with the tobacco plant type assignment of 1, and the minimum value of the upper leaf area index proportion of the tobacco with the tobacco plant type assignment of 2, and obtain the first critical leaf area index proportion through the tobacco plant type confirmation model;

[0044] The calculation expression of the first critical leaf area index proportion is as follows:

[0045]

[0046] Among them, θ 1 represents the first critical leaf area index proportion, represents the maximum value of the upper leaf area index proportion corresponding to the tobacco of the first plant type, represents the minimum value of the upper leaf area index proportion corresponding to the tobacco of the second plant type;

[0047] S52. Obtain the maximum value of the upper leaf area index proportion of the tobacco with the tobacco plant type assignment of 2, and the minimum value of the upper leaf area index proportion of the tobacco with the tobacco plant type assignment of 3, and obtain the second critical leaf area index proportion through the tobacco plant type confirmation model;

[0048] The calculation expression of the second critical leaf area index proportion is as follows:

[0049]

[0050] Among them, θ 2 represents the second critical leaf area index proportion, represents the maximum value of the upper leaf area index proportion corresponding to the tobacco of the second plant type, represents the minimum value of the upper leaf area index proportion corresponding to the tobacco of the third plant type.

[0051] The beneficial effects of adopting the above further solution are as follows: Based on a sufficient amount of plant type data of tobacco at different growth and development stages and the ratio of the upper leaf area index of the corresponding tobacco, the critical index for dividing different plant types is determined, providing a clear classification standard for quantitatively determining the tobacco plant type.

[0052] Further, S6 includes the following steps:

[0053] S61. Obtain the ratio of the upper leaf area index of any tobacco.

[0054] S62. According to the ratio of the upper leaf area index of the tobacco, use the tobacco plant type confirmation model to calculate the quantified value of the tobacco model of the tobacco.

[0055] S63. If the quantified value of the tobacco model of the tobacco is less than the first critical leaf area index ratio, the tobacco plant type of the tobacco is the first plant type.

[0056] S64. If the quantified value of the tobacco model of the tobacco is greater than the first critical leaf area index ratio and less than the second critical leaf area index ratio, the tobacco plant type of the tobacco is the second plant type.

[0057] S65. If the quantified value of the tobacco model of the tobacco is greater than the second critical leaf area index ratio, the tobacco plant type of the tobacco is the third plant type.

[0058] The beneficial effects of adopting the above further solution are as follows: The present invention provides a specific method for confirming the tobacco plant type of any obtained tobacco based on the tobacco plant type confirmation model, realizing the efficient and accurate classification of tobacco into the first plant type, the second plant type or the third plant type, applicable to all stages of tobacco growth and development, and providing a guarantee for cultivating high-quality tobacco and comprehensively coordinating the advantageous traits of high quality and high yield of tobacco. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0060] Figure 1 It is a flowchart of the steps of a method for determining the tobacco plant type based on the leaf area index ratio in an embodiment of the present invention.

[0061] Figure 2(a) is a quantitative relationship diagram of the ratio of the upper leaf area index to the ratio of the middle leaf area index in an embodiment of the present invention.

[0062] Figure 2(b) is a quantitative relationship diagram of the ratio of the upper leaf area index to the lower leaf area ratio index in the embodiment of the present invention.

[0063] Figure 3 It is a schematic diagram of the quantitative statistical relationship between the ratio of the upper leaf area index and the quantified value of the tobacco plant type in the embodiment of the present invention.

[0064] Figure 4 It is a schematic diagram of the correct rate of quantitatively determining the tobacco plant type in the embodiment of the present invention. Detailed implementation manners

[0065] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Usually, the components of the embodiments of the present invention described and shown here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0066] As Figure 1 shown, in an embodiment of the present invention, the present invention provides a method for determining the tobacco plant type based on the ratio of the leaf area index, including the following steps:

[0067] S1. Set the interaction experiment of nitrogen fertilizer and planting density of tobacco to obtain several experimental groups with unique and different nitrogen fertilizer gradients and planting densities;

[0068] In the interaction experiment of nitrogen fertilizer and planting density of tobacco in S1, both the nitrogen fertilizer gradient and the planting density level are not less than 2.

[0069] S2. According to the preset stage time, obtain the ratio of the upper leaf area index, the ratio of the middle leaf area index, and the ratio of the lower leaf area index of each selected tobacco in each experimental group;

[0070] S2 includes the following steps:

[0071] S21. According to the preset stage time, divide several selected tobaccos in each experimental group into parts at the first growth and development stage, the second growth and development stage, and the third growth and development stage respectively, and determine the upper leaves, middle leaves, and lower leaves of each tobacco. Among them, the lower leaves are the first to sixth tobacco leaves from the root to the top of the tobacco, the middle leaves are the seventh to twelfth tobacco leaves from the root to the top of the tobacco, and the upper leaves are the thirteenth to eighteenth tobacco leaves from the root to the top of the tobacco;

[0072] S22. Measure the leaf length and leaf width of the upper, middle, and lower leaves of each selected tobacco in each test group, and obtain the leaf area of each leaf position;

[0073] The calculation expression for the leaf area of each leaf position is as follows:

[0074] s leaf = l × w × α area

[0075] where s leaf represents the leaf area of the tobacco leaf, l represents the leaf length of the tobacco leaf, w represents the leaf width of the tobacco leaf, and α area represents the tobacco leaf area coefficient, where the tobacco leaf area coefficient is 0.6345;

[0076] S23. According to the leaf area of each leaf position, calculate the upper leaf area index, middle leaf area index, and lower leaf area index of each selected tobacco in each test group respectively;

[0077] The calculation expressions for the upper leaf area index, middle leaf area index, and lower leaf area index of each tobacco are as follows respectively:

[0078]

[0079] where, represents the upper leaf area index, upi represents the i-th upper leaf, represents the area of the i-th upper leaf, n p represents the number of tobaccos per unit land area, U la represents the unit land area, represents the middle leaf area index, midi represents the i-th middle leaf, represents the area of the i-th middle leaf, represents the lower leaf area index, boti represents the i-th lower leaf, represents the area of the i-th lower leaf;

[0080] S24. According to the upper leaf area index, middle leaf area index, and lower leaf area index of each tobacco, calculate the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each test group;

[0081] The calculation expressions for the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio are as follows respectively:

[0082]

[0083] where θ upRepresents the proportion of the upper leaf area index, θ mid Represents the proportion of the middle leaf area index, θ bot Represents the proportion of the lower leaf area index.

[0084] S3. Based on the proportion of the upper leaf area index, the proportion of the middle leaf area index, and the proportion of the lower leaf area index of each selected tobacco in each experimental group, a preliminary confirmed tobacco plant type is obtained;

[0085] The preliminary confirmed tobacco plant type in S3 includes the first plant type, the second plant type, and the third plant type;

[0086] For the first plant type, the proportion of the lower leaf area index is greater than the proportion of the upper leaf area index and the proportion of the middle leaf area index; for the second plant type, the proportion of the middle leaf area index is greater than the proportion of the upper leaf area index and the proportion of the lower leaf area index; for the third plant type, the proportion of the upper leaf area index is greater than the proportion of the middle leaf area index and the proportion of the lower leaf area index.

[0087] S4. Based on the preliminary confirmed tobacco plant type, assign values to the plant types of each selected tobacco at each growth and development stage in each experimental group, record the proportion of the upper leaf area index correspondingly, and construct a tobacco plant type confirmation model based on the proportion of the leaf area index;

[0088] S4 includes the following steps:

[0089] S41. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each experimental group is of the first plant type, assign a value of 1 to the selected tobacco and record the proportion of the upper leaf area index;

[0090] S42. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each experimental group is of the second plant type, assign a value of 2 to the selected tobacco and record the proportion of the upper leaf area index;

[0091] S43. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each experimental group is of the third plant type, assign a value of 3 to the selected tobacco and record the proportion of the upper leaf area index;

[0092] S44. Based on the assigned values and the corresponding proportions of the upper leaf area index of each selected tobacco, construct a tobacco plant type confirmation model based on the proportion of the leaf area index;

[0093] The calculation expression of the tobacco plant type confirmation model is as follows:

[0094] P = 6.74θ up + 0.17

[0095] Among them, P represents the quantified value of the tobacco model.

[0096] S5. Based on the tobacco plant type assignment result and the corresponding upper leaf area index ratio, through the tobacco plant type confirmation model, obtain the first critical leaf area index ratio and the second critical leaf area index ratio;

[0097] The S5 includes the following steps:

[0098] S51. Obtain the maximum value of the upper leaf area index ratio of the tobacco with the tobacco plant type assignment of 1, and the minimum value of the upper leaf area index ratio of the tobacco with the tobacco plant type assignment of 2, and through the tobacco plant type confirmation model, obtain the first critical leaf area index ratio;

[0099] The calculation expression of the first critical leaf area index ratio is as follows:

[0100]

[0101] where θ 1 represents the first critical leaf area index ratio, represents the maximum value of the upper leaf area index ratio corresponding to the tobacco of the first plant type, represents the minimum value of the upper leaf area index ratio corresponding to the tobacco of the second plant type;

[0102] S52. Obtain the maximum value of the upper leaf area index ratio of the tobacco with the tobacco plant type assignment of 2, and the minimum value of the upper leaf area index ratio of the tobacco with the tobacco plant type assignment of 3, and through the tobacco plant type confirmation model, obtain the second critical leaf area index ratio;

[0103] The calculation expression of the second critical leaf area index ratio is as follows:

[0104]

[0105] where θ 2 represents the second critical leaf area index ratio, represents the maximum value of the upper leaf area index ratio corresponding to the tobacco of the second plant type, represents the minimum value of the upper leaf area index ratio corresponding to the tobacco of the third plant type.

[0106] S6. Based on the first critical leaf area index ratio and the second critical leaf area index ratio, use the tobacco plant type confirmation model to confirm the tobacco plant type of any arbitrarily obtained tobacco.

[0107] The S6 includes the following steps:

[0108] S61. Obtain the upper leaf area index ratio of any arbitrarily obtained tobacco;

[0109] S62. Calculate the quantified value of the tobacco model for the tobacco according to the ratio of the upper leaf area index of the tobacco by using the tobacco plant type confirmation model;

[0110] S63. If the quantified value of the tobacco model for the tobacco is less than the first critical leaf area index ratio, then the tobacco plant type of the tobacco is the first plant type;

[0111] S64. If the quantified value of the tobacco model for the tobacco is greater than the first critical leaf area index ratio and less than the second critical leaf area index ratio, then the tobacco plant type of the tobacco is the second plant type;

[0112] S65. If the quantified value of the tobacco model for the tobacco is greater than the second critical leaf area index ratio, then the tobacco plant type of the tobacco is the third plant type.

[0113] In a practical example of the present invention, the tobacco variety with the model number K326 is adopted, and the interaction experiment of nitrogen fertilizer and planting density of tobacco is carried out under the field environment in 2021. The two-factor split-plot experiment design is adopted, the main factor is the nitrogen fertilizer application rate, and two gradient levels are set: 90 kg / ha -1 and 105 kg / ha -1 ; the secondary factor is the planting density, and three levels are set: 1.52×10 4 plants / ha -1 、1.67×10 4 plants / ha -1 and 1.85×10 4 plants / ha -1 , the row spacing is 1.2 m, and the plant spacing is 55 cm, 50 cm and 45 cm respectively, with a total of 6 treatments and repeated 3 times. After the tobacco seedlings are transplanted, according to the preset stage time, the leaf length and leaf width of each leaf of the tobacco are measured in the field at 60 days (the first growth and development stage), 75 days (the second growth and development stage) and the mature stage (the third growth and development stage) respectively, and the leaf area (leaf length × leaf width × 0.6345) and the leaf area index ratio of each part (lower, middle, upper) (the leaf area index of this part / the whole plant leaf area index) are calculated. According to the previous research results, the 1st to 6th leaves are divided into lower leaves from bottom to top, the 7th to 12th leaves are middle leaves, and the 13th to 18th leaves are upper leaves.

[0114] The change rules of the leaf area index ratio of different parts of tobacco under different nitrogen fertilizer and density interaction treatments are shown in Table 1:

[0115] Table 1

[0116]

[0117]

[0118] It can be found from Table 1 that under the interaction of different nitrogen fertilizers and densities, the proportion of the leaf area index of the upper leaves shows a gradually increasing trend with the growth process of tobacco, the proportion of the leaf area index of the lower leaves shows a gradually decreasing trend with the growth process of tobacco, while the variation law of the proportion of the leaf area index of the middle leaves is different from 60 days to 75 days, and the proportion of the leaf area index shows a basically decreasing trend from 75 days to the mature period. According to the specific methods of steps S3 and S4 of the present invention, the definitions and corresponding assignments of the regular trapezoid (the first plant type), hexagon (the second plant type) and inverted trapezoid (the third plant type) of tobacco are made, that is, the regular trapezoid is assigned 1, the hexagon is assigned 2, and the inverted trapezoid is assigned 3. It is found from Table 1 that the plant types of tobacco in this practical example all change from 1 or 2 to 2 or 3, reflecting the transformation of the tobacco plant type from a regular trapezoid to a hexagon and from a hexagon to an inverted trapezoid 60 days after transplanting.

[0119] As shown in Figure 2(a), in this practical example, the quantitative relationship between the proportion of the leaf area index of the upper leaves and the proportion of the leaf area index of the middle and lower leaves is constructed. It can be seen from Figure 2 that there is a significant quadratic function relationship between the proportion of the leaf area index of the upper leaves and the proportion of the leaf area index of the middle leaves, indicating that the proportion of the leaf area index of the middle leaves first increases and then decreases with the proportion of the leaf area index of the upper leaves; the expression of the quantitative relationship between the proportion of the leaf area index of the upper leaves and the proportion of the leaf area index of the middle leaves is as follows:

[0120] θ mid =-2.57(θ up ) 2 +1.37θ up +0.24

[0121] As shown in Figure 2(b), there is a significant negative linear relationship between the proportion of the leaf area index of the upper leaves and the proportion of the leaf area index of the lower leaves, indicating that the proportion of the leaf area index of the lower leaves decreases with the increase of the proportion of the leaf area index of the upper leaves. The expression of the quantitative relationship between the proportion of the leaf area index of the upper leaves and the proportion of the leaf area index of the lower leaves is as follows:

[0122] θ bot =-0.82θ up +0.55

[0123] Such as Figure 3As shown, since the proportion of the upper leaf area index gradually increases with the growth process of tobacco, and there is a strong correlation between the proportion of the upper leaf area index and those of the middle and lower leaves, it can better represent the change trend of the tobacco plant type. A quantitative statistical relationship is established between the proportion of the upper leaf area index and the quantified value of the tobacco plant type, and it is found that there is a significant linear positive correlation between the two. The quantified value of the tobacco plant type can be better estimated through the proportion of the upper leaf area index. According to S5 of the present invention, in Table 1, the maximum value of the proportion of the upper leaf area index with a plant type quantified value of 1 is 0.18, while the minimum value of the proportion of the upper leaf area index with a plant type quantified value of 2 is 0.21. The average of these two data is 0.2, and this value is the demarcation value of the proportion of the upper leaf area index for distinguishing between a positive trapezoid and a hexagon; for the distinction between a hexagon and an inverted trapezoid, the maximum value of the proportion of the upper leaf area index with a plant type quantified value of 2 is 0.35, while the minimum value of the proportion of the upper leaf area index with a plant type quantified value of 3 is 0.36. The average of these two data is 0.36. Through Figure 3 the quantitative model between the proportion of the upper leaf area index determined in

[0124] and the quantified tobacco plant type, the quantified values for the demarcation of the tobacco plant type are calculated to be 1.5 and 2.6. That is, the first critical leaf area index proportion and the second critical leaf area index proportion are 1.5 and 2.6 respectively. When the quantified value of the tobacco plant type is less than or equal to 1.5, the plant type of the tobacco can be considered a positive trapezoid or a tower shape (the first plant type); when the quantified value of the tobacco plant type is greater than 1.5 and less than or equal to 2.6, the plant type of the tobacco can be considered a hexagon or a waist drum shape (the second plant type); when the quantified value of the tobacco plant type is greater than 2.6, the plant type of the tobacco can be considered an inverted trapezoid or an umbrella shape (the third plant type). Figure 4 As shown, in this practical example, 15 independent sets of test data (involving different locations, varieties, and years) are used to Figure 3 verify the plant type prediction model established in

[0125] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A method for determining the tobacco plant type based on the ratio of leaf area index, characterized in that, It includes the following steps: S1. Set up the interaction experiment of nitrogen fertilizer and planting density for tobacco, and obtain several experimental groups with unique and different nitrogen fertilizer gradients and planting densities; S2. According to the preset stage time, obtain the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group; S3. Based on the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group, obtain the preliminary confirmed tobacco plant type; S4. Based on the preliminary confirmed tobacco plant type, assign values to the plant types of each selected tobacco in each experimental group at each growth and development stage, record the upper leaf area index ratio correspondingly, and construct a tobacco plant type confirmation model based on the leaf area index ratio; S5. Based on the tobacco plant type assignment results and the corresponding upper leaf area index ratio, through the tobacco plant type confirmation model, obtain the first critical leaf area index ratio and the second critical leaf area index ratio; S6. Based on the first critical leaf area index ratio and the second critical leaf area index ratio, use the tobacco plant type confirmation model to confirm the tobacco plant type of any obtained tobacco.

2. The tobacco plant type determination method based on the leaf area index ratio according to claim 1, wherein In the interaction experiment of nitrogen fertilizer and planting density for tobacco in S1, both the nitrogen fertilizer gradient and the planting density level are not less than 2.

3. The method for determining the tobacco plant type based on the leaf area index ratio according to claim 2, wherein S2 includes the following steps: S21. According to the preset stage time, divide several selected tobaccos in each experimental group into parts at the first growth and development stage, the second growth and development stage, and the third growth and development stage respectively, and determine the upper leaves, middle leaves, and lower leaves of each tobacco. Among them, the lower leaves are the first to sixth tobacco leaves from the root to the top of the tobacco, the middle leaves are the seventh to twelfth tobacco leaves from the root to the top of the tobacco, and the upper leaves are the thirteenth to eighteenth tobacco leaves from the root to the top of the tobacco; S22. Measure the leaf length and leaf width of the upper leaves, middle leaves, and lower leaves of each selected tobacco in each experimental group respectively to obtain the leaf area of each leaf position; The calculation expression of the leaf area of each leaf position is as follows: Among them, represents the leaf area of the tobacco leaf, l represents the leaf length of the tobacco leaf, and w represents the leaf width of the tobacco leaf. represents the tobacco leaf area coefficient, where the tobacco leaf area coefficient is 0.6345. S23. According to the leaf area of each leaf position, calculate the upper leaf area index, middle leaf area index, and lower leaf area index of each selected tobacco in each experimental group respectively; The calculation expressions of the upper leaf area index, middle leaf area index, and lower leaf area index of each tobacco are as follows: Among them, represents the upper leaf area index, represents the i-th upper leaf, represents the area of the i-th upper leaf, represents the number of tobacco plants per unit land area, represents the unit land area, represents the middle leaf area index, represents the i-th middle leaf, represents the area of the i-th middle leaf, represents the lower leaf area index, represents the i-th lower leaf, represents the area of the i-th lower leaf; S24. According to the upper leaf area index, middle leaf area index, and lower leaf area index of each tobacco, calculate the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio of each selected tobacco in each experimental group; The calculation expressions of the upper leaf area index ratio, middle leaf area index ratio, and lower leaf area index ratio are as follows: Among them, represents the proportion of the leaf area index of upper leaves, represents the proportion of the leaf area index of middle leaves, represents the proportion of the leaf area index of lower leaves.

4. The method for determining the tobacco plant type based on the leaf area index ratio according to claim 3, characterized in that, The preliminary confirmed tobacco plant type in S3 includes the first plant type, the second plant type, and the third plant type; The ratio of the leaf area index of the lower leaves of the first plant type is greater than the ratio of the leaf area index of the upper leaves and the ratio of the leaf area index of the middle leaves; the ratio of the leaf area index of the middle leaves of the second plant type is greater than the ratio of the leaf area index of the upper leaves and the ratio of the leaf area index of the lower leaves; the ratio of the leaf area index of the upper leaves of the third plant type is greater than the ratio of the leaf area index of the middle leaves and the ratio of the leaf area index of the lower leaves.

5. The method for determining the tobacco plant type based on the leaf area index ratio according to claim 4, wherein The said S4 includes the following steps: S41. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each test group is of the first plant type, assign the value of 1 to the selected tobacco and record the ratio of the leaf area index of its upper leaves; S42. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each test group is of the second plant type, assign the value of 2 to the selected tobacco and record the ratio of the leaf area index of its upper leaves; S43. Respectively at the first growth and development stage, the second growth and development stage, and the third growth and development stage of the tobacco, when the selected tobacco in each test group is of the third plant type, assign the value of 3 to the selected tobacco and record the ratio of the leaf area index of its upper leaves; S44. Based on the assignment of each selected tobacco and the corresponding ratio of the leaf area index of the upper leaves, construct a tobacco plant type confirmation model based on the ratio of the leaf area index; The calculation expression of the said tobacco plant type confirmation model is as follows: Among them, represents the quantization value of the tobacco model.

6. The method for determining the tobacco plant type based on the leaf area index ratio according to claim 5, wherein The said S5 includes the following steps: S51. Obtain the maximum value of the ratio of the leaf area index of the upper leaves of the tobacco with a tobacco plant type assignment of 1, and the minimum value of the ratio of the leaf area index of the upper leaves of the tobacco with a tobacco plant type assignment of 2, and obtain the first critical leaf area index ratio through the tobacco plant type confirmation model; The calculation expression of the said first critical leaf area index ratio is as follows: Among them, represents the first critical leaf area index ratio, represents the maximum value of the upper leaf area index ratio corresponding to the tobacco of the first plant type, represents the minimum value of the upper leaf area index ratio corresponding to the tobacco of the second plant type; S52. Obtain the maximum value of the ratio of the leaf area index of the upper leaves of the tobacco with a tobacco plant type assignment of 2, and the minimum value of the ratio of the leaf area index of the upper leaves of the tobacco with a tobacco plant type assignment of 3, and obtain the second critical leaf area index ratio through the tobacco plant type confirmation model; The calculation expression of the said second critical leaf area index ratio is as follows: Among them, represents the second critical leaf area index ratio, represents the maximum value of the upper leaf area index ratio corresponding to the tobacco of the second plant type, represents the minimum value of the upper leaf area index ratio corresponding to the tobacco of the third plant type.

7. The method for determining the tobacco plant type based on the leaf area index ratio according to claim 6, characterized in that, The said S6 includes the following steps: S61. Obtain the ratio of the leaf area index of the upper leaves of any tobacco; S62. According to the ratio of the leaf area index of the upper leaves of this tobacco, calculate the tobacco model quantization value of this tobacco by using the tobacco plant type confirmation model; S63. If the tobacco model quantization value of this tobacco is less than the first critical leaf area index ratio, then the tobacco plant type of this tobacco is the first plant type; S64. If the tobacco model quantization value of this tobacco is greater than the first critical leaf area index ratio and less than the second critical leaf area index ratio, then the tobacco plant type of this tobacco is the second plant type; S65. If the tobacco model quantization value of this tobacco is greater than the second critical leaf area index ratio, then the tobacco plant type of this tobacco is the third plant type.

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