A method for determining the row direction of intercropping crops based on expected light threshold

Abstract

The present invention discloses a method for determining the planting row direction of intercrops based on the expected light threshold calculation, comprising the following steps: (1) determining basic data: using query software to obtain the geographical information of the planting point in the rubber planting area; obtaining the threshold of the photosynthetic effective time period of the crop; measuring the height of the mature rubber tree; (2) calculating the extreme value of the direct sunlight duration between the rows: simulating and calculating the direct sunlight duration and time period between the rows of the planting point in different months; (3) determining the planting row direction: combining the direct sunlight extreme values ​​of different row directions in step (2), predicting the optimal light threshold rubber tree planting row direction suitable for planting crops in the rubber garden. The method is based on the spatiotemporal distribution law of light in the rubber garden with different planting rows under the change of the direct sunlight point, combined with the crop growth period and photosynthetic efficiency, to achieve the prediction of the optimal light threshold, the analysis and judgment method is simple and easy to operate, and the result has a high reference application value.

Description

Technical Field

[0001] The present invention relates to the technical field of intercrop cultivation and farming, and in particular to a method for determining an intercrop planting row direction based on an expected light threshold. Background Art

[0002] Natural rubber is the only renewable resource among the four major industrial raw materials. Previously, more than 99% of the Brazilian rubber tree planting methods in my country were planted with equal row spacing. In this planting model, light-loving crops can be intercropped between rows only in the young tree stage (4 years before planting). 4 years after the rubber trees are planted, as the rubber trees grow, the density of the rubber garden will increase and the root system of the rubber trees between rows will be widely distributed. In the subsequent production cycle of several decades, only a small amount of shade-loving crops can be planted, which greatly limits the development of the intercropping model in the rubber garden, and there are a lot of problems such as low efficiency in the use of land and space resources.

[0003] The full-cycle intercropping model rubber plantation construction technology adopts upright narrow-cropping varieties of rubber trees in a wide and narrow row planting model. Without significantly reducing rubber production, it can optimize and improve the underground space environment of the rubber plantation, greatly reduce the competition for rubber-cropping space and nutrients, and multiple crops can be grown throughout the entire rubber plantation production cycle and mechanized operations are easier, which is more conducive to the development of under-forest intercropping production.

[0004] However, in the process of promoting this model, the row direction is usually determined by terrain and experience, and after the forest is established, the crops are matched according to the light conditions between the wide rows under the forest. For rubber plantations that need to be operated for up to 30 years, it is difficult to form continuous and large-scale production if the intercropping pattern is determined by constantly matching suitable intercrops according to the interrow light. If there is a method to predict the extreme value of interrow light in this type of mature rubber plantation, the types of crops planted in the area can be planned in advance, the corresponding infrastructure can be provided, unnecessary investment can be reduced, and the rubber plantation of this model can be better promoted. Therefore, in the context of the country's promotion of the renewal of new and old rubber plantations and the promotion of full-cycle intercropping model rubber plantations, a method for predicting the row direction configuration of intercrops based on the expected light threshold of mature rubber plantations with a full-cycle planting model is proposed. Summary of the invention

[0005] In response to the above-mentioned prior art, the present invention provides a method for determining the planting direction of intercrops based on the expected light threshold. The optimal planting direction of intercrops is determined according to the height of rubber trees, the changing pattern of the direct sunlight point at the planting point and the photosynthetic efficiency of crops, and regional planning is carried out. The method is simple and easy to operate.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A method for determining the row direction of intercropping crops based on an expected light threshold comprises the following steps:

[0008] (1) Determination of basic data: Obtain geographical information on the longitude, latitude, solar altitude angle, and solar azimuth angle of the planting point in the rubber planting area; Select light-loving crops and shade-loving crops as representatives to measure their daily variation curves of photosynthetic rate and obtain the photosynthetic effective time period threshold of the crop; Select rubber tree varieties suitable for the full-cycle planting mode and measure the height of mature rubber trees;

[0009] (2) Calculating the extreme value of the direct sunlight duration between rows: Based on the row direction of rubber tree planting, the wide row spacing of the rubber plantation in the full-cycle planting mode, and the basic data in step (1), simulate and calculate the direct sunlight duration and time period between rows at the planting point in different months;

[0010] (3) Determine the planting direction: Based on the crop planting season, the daily change curve of photosynthetic rate, and the extreme values ​​of direct sunlight in different directions in step (2), predict the optimal light threshold for planting rubber trees in the rubber garden.

[0011] The beneficial effect of the present invention is that: based on the geographical characteristics that my country's rubber planting areas are concentrated in the south of the Tropic of Cancer, combined with the relationship between parameters such as the sun's direct point, the sun's altitude angle, and the tree height, the method calculates the light thresholds between rows in different directions under the rubber tree forest at the planting point, which can achieve scientific prediction and break the traditional empirical judgment.

[0012] The present invention can set the optimal planting direction according to the intercrops' light demand. The intercrops' light demand can be measured by a photosynthetic meter, which can be completed in a short time, or by querying literature. The method is simple and easy to operate, and the result has a high reference value for regional planning and large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described here are used to provide a further understanding of the present invention and constitute a part of this application.

[0014] Figure 1 A schematic diagram of two rows of rubber tree planting directions and sunlight paths in a method for determining intercrop planting directions based on an expected light threshold value of the present invention;

[0015] Figure 2 A schematic diagram of the relationship between a rubber tree and the path of sunlight, a solar altitude angle, and a solar direction angle in a method for determining the row direction of intercropping plants based on an expected light threshold value of the present invention;

[0016] Figure 3 The daily variation curve of the photosynthetic rate of corn in Example 1 of the method for determining the planting row direction of intercrops based on the expected light threshold value of the present invention;

[0017] Figure 4 This is a curve diagram of the daily variation of the photosynthetic rate of Amorphophallus konjac in Example 2 of the method for determining the planting row direction of intercrops based on the expected light threshold of the present invention. DETAILED DESCRIPTION

[0018] In order to better understand the technical content of the present invention, specific embodiments are provided below, and the present invention is further described in conjunction with the accompanying drawings.

[0019] A method for determining the row direction of intercropping crops based on an expected light threshold comprises the following steps:

[0020] (1) Determination of basic data: The longitude and latitude of the planting point in my country's rubber planting area are obtained through longitude and latitude positioning software. The solar altitude angle (A) and solar azimuth angle (B) of the planting point at a certain time are queried through the sunrise, sunset and moon phase mobile phone APP software or solar altitude angle software, and the effective threshold geographical information at a certain time from January to December can be queried; due to the laws of solar revolution and rotation, combined with the date when the direct sunlight point moves between the Tropic of Capricorn and the equator, the time when the direct sunlight shines on the Tropic of Capricorn and the Tropic of Cancer each year is June 22 and December 22 respectively. In order to facilitate the calculation of the extreme values ​​of the planting point when the direct sunlight point is at the southernmost (Tropic of Capricorn) and the northernmost (Tropic of Cancer), the hourly value between sunrise and sunset on the 22nd of each month is queried. Select light-loving crops and shade-loving crops as representatives to measure their daily variation curves of photosynthetic rate, set a photosynthetic meter to measure the photosynthetic rate at each time, and process the results to obtain the daily variation curve of photosynthetic rate. The threshold of the photosynthetic effective time period of intercrops is obtained through the variation curve. A rubber tree variety Reyan 7-20-59 suitable for the full-cycle planting model was selected, and the height of its mature rubber trees was measured. The crown amplitude (L) and height (h) of rubber trees planted for 10, 15, 20, and 25 years or more under this model were observed using a height meter to determine the growth period and light requirements of representative crops of the light-loving / shade-loving type in the region, for example, the effective photosynthetic time period, light saturation point, light compensation point, and light duration requirements.

[0021] (2) Calculate the extreme value of direct sunlight duration between rows: Substitute the preset rubber tree planting row direction (C, north is 0°, indicating that the planting direction is north-south), the full-cycle planting mode rubber plantation row spacing of 20m and the basic data in step (1) to obtain the formula Calculate the projection of the rubber tree (a) and the length of the vertical line of the planting row (b) at the planting point at that moment. The length of the vertical line of the planting row (b) is the projection width of the rubber trees between the wide rows (b).

[0022] When the projection width (b) is greater than the row width and is greater than or equal to 20 meters, the rubber tree rows do not receive direct sunlight. When the projection width is less than 20 meters, the rows begin to receive sunlight. When the projection width is less than the average crown width (L) of the rubber tree, the intercropping area receives sunlight in its entirety. From this, we can infer the extreme value of the direct sunlight duration that each point receives every day in that month; that is, we simulate and calculate the direct sunlight duration and time period between rows of the planting point in different months;

[0023] (3) Determining the planting direction: Based on the crop planting season, the daily variation curve of photosynthetic rate and other indicators in step (1), combined with the extreme values ​​of direct sunlight in different directions in step (2), the optimal light threshold for planting rubber trees in the rubber garden is predicted.

[0024] Example 1

[0025] Take the example of planting light-loving crops such as corn between rows in the Danzhou branch of the Chinese Academy of Tropical Agricultural Sciences in Danzhou City, Hainan Province, a rubber-planting area:

[0026] Corn is an annual herbaceous plant of the Poaceae family. It is an important food crop and feed crop. It is also the crop with the highest total output in the world. Its planting area is second only to rice and wheat. Corn is a light-loving crop. Compared with other crops, its light saturation point is higher. Experiments have shown that corn can grow at a photosynthetic active radiation of 2000 μmol / (m 2 ·s), the light saturation point has never been measured. Corn is a short-day crop with a growth cycle of 3 to 5 months. It requires at least 7 to 9 hours of sunshine per day from sowing to milky stage, and more than 8 hours per day from milky stage to maturity. The peak of the daily variation of photosynthetic rate is mostly in the morning. The growth period of corn is about 120 days. Considering that Hainan's rainy season is from May to October every year, this implementation plan sets corn sowing after May and harvesting before October. Figure 3 This is a diagram showing the daily changes in the net photosynthetic rate (Pn) of corn during the grain filling period. The arrow indicates the moment when the photosynthesis of the corn crop begins (or ends) and becomes more meaningful.

[0027] (1) Determination of basic data: The longitude and latitude of the planting site in the rubber planting area of ​​our province were obtained through the longitude and latitude positioning software. The longitude is 109°29′48″ and the latitude is 19°30′30″. The maximum solar altitude angle of the planting site at 8:00 on May 22 was 24.95° and the minimum solar azimuth angle was 75.78° through the sunrise, sunset and moon phase mobile phone APP software. The maximum solar altitude angle after 18:00 in the afternoon was 15.64° and the minimum solar azimuth angle was 286.89° (due north is 0°).

[0028] Before 8:00 on September 22, the maximum solar altitude angle was 20.21°, and the minimum solar azimuth angle was 97.46°. After 17:00 in the afternoon, the maximum solar altitude angle was 22.09°, and the minimum solar azimuth angle was 261.59° (due north is 0°).

[0029] The crown width (L) of mature rubber trees was observed using a height meter and was found to be approximately 4m and 18m respectively.

[0030] (2) Calculate the extreme value of direct sunlight duration between wide rows: Substitute the preset rubber tree planting row direction (C, north is 0°), the wide row spacing of the rubber plantation in the full-cycle planting mode of 20m, and the basic data in step (1) according to Figure 1 to Figure 3 , the crown of the rubber tree is generally 4 meters, and the width of the intercropping area is 12 meters. When the projection width is greater than 16 meters (4 meters is the projection of the crown of the rubber tree), there is no light between the rows; when it is close to zero, all sites between the rows receive light, so the projection width (b) is selected in the range of [0, 12] for calculation. Calculate the rubber tree projection (a) and the vertical length (b) of the planting row at the planting point from 8:00 to 17:00, and select the rubber tree planting row direction with a projection width (b) in [0, 12];

[0031] The specific experimental steps are recorded as follows:

[0032] The C value is calculated according to the 5° arithmetic progression. In Tables n and n', when the value b is less than 12, the tree starts to receive light, and the space between each planting direction is the time period with light. When b is approximately less than 2m, the space between rows is the time period when the tree is fully exposed to light. When b is greater than or equal to 12, there is no light, and the time extension line is calculated based on a time interval of 1 hour, as shown in the table below (only some of the values ​​are taken).

[0033] Determine the planting direction: The height of mature rubber trees generally has a stable value (about 18 meters). Therefore, according to the changing pattern of the direct sunlight point in different months, the inter-row lighting conditions of all planting directions at a certain planting point (altitude, longitude, latitude) can be predicted. The light requirements of the crops to be planted during their growth period (light-loving or shade-loving) also have certain rules. According to the light threshold of this planting point during the growth period, the optimal planting direction is matched with the maximum (or minimum) light conditions.

[0034] Table 1 shows the calculated values ​​at 7:00 on May 22:

[0035]

[0036]

[0037] Table 2 shows the calculated values ​​at 8 points:

[0038]

[0039] Table 3 shows the calculated values ​​at 18:30

[0040]

[0041] Calculate from 7:00 to 18:30 in the afternoon, and then use Excel to calculate the projection width values ​​between rows at different times for various planting directions as shown in the following table:

[0042] Table n projection width values ​​of various planting directions at different times:

[0043]

[0044]

[0045] The projection extreme values ​​are calculated at each moment with 5° as the arithmetic interval, and the values ​​obtained are shown in the table n above. According to this method, the projection extreme values ​​on the 22nd day of each month are calculated in turn, covering the crop growth period.

[0046] Table 4 shows the extreme value calculation method at 7:00 on September 22:

[0047]

[0048] Table 5 shows the extreme value calculation method at 8:00:

[0049]

[0050]

[0051] Table 6 shows the calculation method of the extreme value at 18:30:

[0052]

[0053] Calculate in sequence until 18:30 in the afternoon, and then use Excel to calculate the projection width values ​​between rows at different times for various planting directions as shown in Table n:

[0054] Table n' projection width values ​​of various planting directions at different times:

[0055]

[0056] Based on the above recorded data and Figure 3It can be seen that the planting row direction C with the maximum light duration on May 22 was about [60°, 125°], and the longest light duration between the rows was about 10 hours, that is, between 8:00 and 17:00; and when C was between [75°, 105°], the time between the rows was completely exposed to direct sunlight was the longest, about 6 hours (8:00-13:00, 12-17:00). The planting row direction C with the minimum light duration was [0°, 25°] & [155°, 180°], with the shortest duration of about 6 hours (10:00-15:00), and the time between the rows was completely exposed to direct sunlight was less than 1 hour (13:00).

[0057] Similarly, it can be experimentally recorded that when the maximum value of the light duration on September 22 was between [75°, 110°], the inter-row sunlight duration was the longest, greater than 8 hours, and when C was [105°, 110°], the inter-row was completely exposed to direct sunlight for about 1 hour (9:00); when the minimum value of the light duration was between [0°, 10°] and [170°, 180°), the inter-row light duration was about 4 hours (11:00-14:00), and there was no period of time when the inter-row was completely exposed to light. Therefore, combined with the light requirements of corn, the daily light duration is greater than 8 hours, the growth period is about 120 days, and the peak photosynthetic efficiency is biased towards the morning. The photosynthesis efficiency of general crops is mainly higher in the morning. Based on the projection width from May to September, although the direct sunlight duration is longest in May when the row direction is 75°-90°, and the sunlight duration is longer in the morning, as the direct sunlight point moves toward the Tropic of Cancer, until September, the morning sunlight duration is longer when the row direction is 90°-105°. When the planting row direction is 105°, the time when the rows are completely exposed to direct sunlight is longer, so the optimal light threshold can be obtained when the planting row direction C is 105°.

[0058] (3) Determining the planting direction: Based on the corn crop planting season, the daily variation curve of photosynthetic rate and other indicators in step (1), combined with the extreme values ​​of direct sunlight in different row directions in step (2), and the light requirements of corn, such as daily light greater than 8 hours, a growing period of about 120 days, and a photosynthetic efficiency peak in the morning, the optimal light threshold for the crop between rows in the rubber plantation can be obtained when the planting direction C is 105°.

[0059] Example 2

[0060] Take the example of planting shade-loving crop Amorphophallus truncatus between rows in the Danzhou Campus of the Chinese Academy of Tropical Agricultural Sciences in Danzhou City, Hainan Province, a rubber-planting area:

[0061] Amorphophallus virosus NEBrown is a perennial herbaceous plant of the Araceae family and the genus Amorphophallus. The tubers of Amorphophallus virosus are rich in starch, and the whole plant can be used as pig feed, which has a certain fattening effect. Amorphophallus virosus prefers diffuse light and weak light, and avoids high temperature and strong light. The light compensation point is about 20μmol / (m 2 ·s), the light saturation point is about 500μmol / (m 2 ·s), the peak of the daily variation of photosynthetic rate tends to be in the morning, the sowing and planting time is generally in April, the seedlings emerge in May, the seedlings are transplanted in October, and the harvest is in November. The growth period affected by light is concentrated in May-October. Figure 4 The daily changes of net photosynthetic rate (Pn) of konjac leaves during the stable period under the condition of 40% light transmittance.

[0062] (1) Basic data acquisition: same as (1) in Implementation Case 1;

[0063] (2) Calculate the maximum duration of direct sunlight between rows: the same as (2) in Implementation Example 1.

[0064] (3) Determine the planting direction: Based on the threshold of direct sunlight between rows in different directions in (2), combined with the light requirements of Amorphophallus konjac, such as avoiding high temperatures and strong direct sunlight, the light compensation point is about 20 μmol / (m 2 ·s), the light saturation point is about 500μmol / (m 2 ·s), the peak of the daily variation of photosynthetic rate is biased towards the morning. When the minimum light duration is from 11:00 to 14:00 on September 22, when the planting direction C is [0°, 10°] & [170°, 180°), the light duration between rows is about 4 hours, and there is no period of time when the crops receive full light duration. The optimal light threshold between rows of the crop in the rubber plantation can be obtained by comprehensively expecting that the planting direction C is [0°, 10°] & [170°, 180°].

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the row direction of intercropping crops based on an expected light threshold, characterized in that: The following steps are involved: (1) Determination of basic data: Obtain geographical information on the longitude, latitude, solar altitude angle, and solar azimuth angle of the planting points in the rubber planting area; Select light-loving crops and shade-loving crops as representatives to measure their daily variation curves of photosynthetic rate and obtain the threshold of the photosynthetic effective time period of the crops; select rubber tree varieties suitable for the full-cycle planting mode and measure the height of mature rubber trees; (2) Calculate the maximum value of direct sunlight duration between rows: Combine the row direction of rubber trees, the wide row spacing of the rubber plantation in the full-cycle planting mode, and the basic data in step (1) to calculate the maximum value of direct sunlight duration between rows. Calculate the projection of the rubber tree at the planting point at this moment (a) and the length of the vertical line of the planting row (b), where a = h / tanA, h is the tree height, A is the solar altitude angle, B is the solar azimuth angle, and C is the rubber tree planting row direction, and simulate and calculate the direct sunlight duration and time period between rows at the planting point in different months; (3) Determine the planting direction: Based on the crop planting season, the daily change curve of photosynthetic rate, and the extreme values ​​of direct sunlight in different directions in step (2), predict the optimal light threshold for planting rubber trees in the rubber garden.

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