Sweet sorghum and corn intercropping planting method and planting device

Abstract

The invention discloses a sweet sorghum and corn intercropping planting method and a planting device. The sweet sorghum and corn intercropping planting method comprises the following steps: applying urea and diammonium phosphate in a sowing field, sowing sweet sorghum and corn at a row ratio of 2:2, covering with film, watering, dripping water under the film every 20 to 30 days, and from the sowing day to the waxy maturity stage, the total irrigation amount is 3750m 3 ·hm ‑2 The row spacing of sweet sorghum is 400×600 mm, the row spacing is 120 mm, and the planting density is 1.67×10 5 Hole·hm ‑2 The corn row spacing is 400×600 mm, the plant spacing is 205 mm, and the planting density is 7.75×10 4 Hole·hm ‑2 The planting device used in the sweet sorghum and corn intercropping planting method comprises a frame and four sowing components. The present invention is suitable for arid and saline-alkali lands in Xinjiang, and establishes a regionally adaptable green crop cultivation mode by utilizing innovative high-quality, safe and efficient cultivation technology and planting devices.

Description

Technical Field

[0001] The present invention relates to the technical field of crop planting, and more specifically to a sweet sorghum and corn intercropping planting method and planting device. Background Art

[0002] Xinjiang is a major livestock breeding province, and drought and salinization have seriously restricted the development of agriculture and animal husbandry.

[0003] Sweet sorghum (scientific name: Sorghum dochna (Forssk.) Snowden ) is an annual plant of the Gramineae family with a wide range of uses. It not only produces grain, but also sugar and syrup. It can also be used for green feed, silage, and hay. It has the characteristics of drought resistance, waterlogging resistance, and salt-alkali resistance. It is not very strict with the environmental conditions for growth. It has a strong adaptability to the soil, especially its tolerance to salt and alkali is stronger than that of corn. Sweet sorghum can grow in soils with a pH value of 5.0-8.5. Sweet sorghum can grow at an accumulated temperature of 2600°C-4500°C above 10°C. Sweet sorghum is a high-energy crop with a photosynthetic conversion rate of up to 18%-28%. Its yield is comparable to that of corn in areas with little rainfall or limited irrigation water. As an important forage raw material, silage corn has the advantages of rapid growth, high yield, high nutritional value, good palatability, and easy storage. It is widely used in animal husbandry production.

[0004] At present, researchers have conducted preliminary explorations on the feasibility of mixed planting of silage corn and forage sorghum. For example, Chinese patent document CN108967081B discloses a method for mixed planting of forage sorghum and silage corn. Through the mixed planting of forage sorghum and silage corn, the complementary advantages between varieties are achieved, and the biomass and quality of crops are improved. However, the planting method is simple, and there is no supporting planting device that can simultaneously complete the entire intercropping process such as seeding and film covering, which increases manpower and material resources, and the planting efficiency is low. Summary of the invention

[0005] An object of the present invention is to provide a sweet sorghum and corn intercropping planting method and planting device, which can fully utilize land, increase biodiversity, and effectively improve planting efficiency.

[0006] In order to achieve these purposes and other advantages according to the present invention, according to one aspect of the present invention, a sweet sorghum and corn intercropping method is provided, comprising the following steps: applying urea and diammonium phosphate in a sowing field, sowing sweet sorghum and corn at a row ratio of 2:2, covering with film, watering, dripping water under the film every 20 to 30 days, and from the sowing day to the waxy maturity stage, the total irrigation amount is 3750 m 3 ·hm -2The row spacing of sweet sorghum is 400×600 mm, the row spacing is 120 mm, and the planting density is 1.67×10 5 Hole·hm -2 The corn row spacing is 400×600 mm, the plant spacing is 205 mm, and the planting density is 7.75×10 4 Hole·hm -2 .

[0007] Preferably, the amount of urea applied is 450 kg·hm -2 The application amount of diammonium phosphate is 375 kg·hm -2 .

[0008] Preferably, the number of times of dripping water under the film is 5 times from the sowing day to the wax maturity stage.

[0009] Preferably, the variety of sweet sorghum is Ketian No. 10, which has a plant height of 410 cm after maturity, green stems, a middle diameter of 2.10 cm, 18 above-ground stems, an average single stem weight of 1200 g, a leaf weight of 160 g, an ear neck length of 45 cm, medium-loose ears, an ear length of 33 cm, an average single ear weight of 175 g, medium-sized, oval, light yellow grains, a thousand-grain weight of 27.8 g, a stem yield of 6200 kg per mu, a juice brix of 19.0%, and a grain yield of 350 kg per mu.

[0010] Preferably, the corn is silage corn - Tunyu 168.

[0011] The present invention also provides a planting device for the sweet sorghum and corn intercropping planting method, comprising:

[0012] A frame, a film-coating shaft, a film-pressing shaft, and four rollers are arranged at the bottom thereof, a ground film is sleeved on the film-coating shaft, film-pressing wheels are arranged at both ends of the film-pressing shaft, a through notch is also opened on the frame, a screw and a fixing rod are installed in parallel in the notch, the screw is composed of a first threaded portion, a second threaded portion, a third threaded portion, and a fourth threaded portion, the second threaded portion and the third threaded portion located in the middle of the screw are respectively provided with threads with the same pitch and symmetrical rotation direction, the first threaded portion and the fourth threaded portion located at both ends of the screw are respectively provided with threads with the same pitch and symmetrical rotation direction, sprockets are arranged at both ends of the screw, the two sprockets are respectively connected to the driving wheels of the motor through chains, and a handle is also arranged on the top of the frame;

[0013] Four sowing components, each of which is provided with a seed storage bin and a sowing wheel, the seed storage bin comprising a rectangular bin and two prismatic bins connected to the bottom sides of the rectangular bin, the sowing wheel is located between the two prismatic bins and connected to the bottoms of the two prismatic bins through a hollow rotating shaft, an opening is provided on the top of the rectangular bin, and through screw holes and a first through hole are provided on the opposite side walls of the rectangular bin for the screw rod and the fixing rod to pass through, and the screw holes on the rectangular bins of the four sowing components are respectively matched and sleeved on the outer peripheries of the first threaded portion, the second threaded portion, the third threaded portion and the fourth threaded portion.

[0014] Preferably, the first threaded portion and the second threaded portion have the same thread rotation direction, the third threaded portion and the fourth threaded portion have the same thread rotation direction, and the thread pitch of the first threaded portion and the fourth threaded portion is twice the thread pitch of the second threaded portion and the third threaded portion.

[0015] Preferably, two hollow rotating shafts are symmetrically arranged on both sides of the seeding wheel, the free ends of the two rotating shafts are respectively borne through the side walls of the two prismatic bins that are close to each other, and sleeves are coaxially installed in the two rotating shafts, a plurality of support rods are connected between the outer wall of the sleeve and the inner wall of the rotating shaft, the two ends of the sleeve are respectively borne through the side walls of the two prismatic bins that are far away from each other, an insertion rod is movably sleeved in the sleeve, and the two ends of the insertion rod respectively pass through the sleeve and are fixedly connected to the side walls of the notch.

[0016] The present invention has at least the following beneficial effects:

[0017] First, the sweet sorghum and corn intercropping method of the present invention establishes a green crop cultivation model suitable for arid and saline-alkali land in Xinjiang, fully utilizes land resources, improves land utilization rate, and facilitates field management;

[0018] Second, the planting device of the present invention can simultaneously complete the entire intercropping process including intercropping sowing and film covering, is easy to operate, saves time and effort, and improves sowing efficiency.

[0019] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a side view of the sowing device in one technical solution of the present invention;

[0021] Figure 2 A top view of the sowing device in one technical solution of the present invention;

[0022] Figure 3 It is a structural schematic diagram of the sowing assembly in one technical solution of the present invention;

[0023] Figure 4 It is a structural schematic diagram of the screw rod and the fixing rod in a technical solution of the present invention;

[0024] Figure 5 The figure is a schematic diagram of the structure of the seeding wheel in one technical solution of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0027] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified; in the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected, set, or detachably connected, set, or connected and set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in specific circumstances. The orientation or position relationship indicated by the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0028] In one technical solution, the present invention provides a method for intercropping sweet sorghum and corn, comprising the following steps: applying urea and diammonium phosphate in the sowing field, sowing sweet sorghum and corn in a row ratio of 2:2, covering with film, watering, dripping water under the film every 20 to 30 days, and from the sowing day to the waxy maturity stage, the total irrigation amount is 3750 m 3 ·hm -2 The row spacing of sweet sorghum is 400×600 mm, the row spacing is 120 mm, and the planting density is 1.67×10 5 Hole·hm -2 The corn row spacing is 400×600 mm, the plant spacing is 205 mm, and the planting density is 7.75×10 4 Hole·hm -2 .

[0029] In another technical solution, the amount of urea applied is 450 kg·hm -2 The application amount of diammonium phosphate is 375 kg·hm -2 .

[0030] In another technical solution, the number of times of dripping water under the film is 5 times from the sowing day to the wax maturity stage.

[0031] In another technical solution, the variety of sweet sorghum is Ketian No. 10, which has a plant height of 410 cm after maturity, a green stem, a middle diameter of 2.10 cm, 18 above-ground stems, an average single stem weight of 1200 g, a leaf weight of 160 g, a spike neck length of 45 cm, medium loose spikes, a spike length of 33 cm, an average single spike weight of 175 g, medium-sized grains, oval, light yellow, 1,000-grain weight of 27.8 g, a stem yield of 6,200 kg per mu, a juice hammer of 19.0%, and a grain yield of 350 kg per mu. In this technical solution, the variety is medium-maturing, with a growth period of 130 days in the northwest region, sowing in late April, germination in early May, heading in late August, and maturity in late September.

[0032] In another technical solution, the corn is silage corn - Tunyu 168. In this technical scheme, the corn seeds were sown on March 31 in the experimental area of ​​the 11th Company of the 12th Regiment of Aral City, Xinjiang Production and Construction Corps (the area has a typical warm temperate continental arid climate, rich light and heat resources, an annual radiation of 9733 MJ·m-2, an average annual sunshine time of 2650~3100 h, an average annual temperature of 10.4℃, an extreme maximum temperature of 40.6℃, an extreme minimum temperature of -23.4℃, a frost-free period of 180~224 d, an annual accumulated temperature ≥10℃ of 3800~4700℃, an average annual precipitation of 40~70 mm, and an average annual evaporation of >2100 mm. The soil is sandy, alkaline, with a pH value of 8.3, and a flat terrain), harvested on August 7, weighed to measure yield, and samples were taken after harvesting to weigh the fresh weight. The test samples were taken back to the laboratory in self-sealing bags using the quartering method, and after being fixed at 105℃ for 20 min, they were dried at 65℃ to constant weight.

[0033] like Figures 1 to 5 As shown, the present invention also provides a planting device for the sweet sorghum and corn intercropping planting method, comprising:

[0034] The frame 100 has a film-coating shaft 101, a film-pressing shaft 102, and four rollers 103 at its bottom. The film-coating shaft 101 is sleeved with a ground film. Both ends of the film-pressing shaft 102 are provided with film-pressing wheels. The frame 100 is also provided with a through notch 104. A screw 105 and a fixing rod 106 are installed in parallel in the notch 104. The screw 105 consists of a first threaded portion 107, a second threaded portion 108, a third threaded portion 109, and a fourth threaded portion 101. The frame 100 is composed of a second threaded portion 108 and a third threaded portion 109 located in the middle of the screw 105, respectively, with threads having the same pitch and symmetric rotation direction, and the first threaded portion 107 and the fourth threaded portion 110 located at both ends of the screw 105 are respectively provided with threads having the same pitch and symmetric rotation direction, and sprockets are provided at both ends of the screw 105, and the two sprockets are respectively connected to the driving wheels of the motor 112 through chains 111, and a handle 113 is also provided on the top of the frame 100;

[0035] Four sowing components 200, each sowing component 200 is provided with a seed storage bin and a sowing wheel 300, the seed storage bin includes a rectangular bin 201, and two prismatic bins 202 connected to both sides of the bottom of the rectangular bin 201, the sowing wheel 300 is located between the two prismatic bins 202, and is connected to the bottoms of the two prismatic bins 202 through a hollow rotating shaft 203, an opening is provided at the top of the rectangular bin 201, and through screw holes 204 and first through holes 205 are provided on the opposite side walls of the rectangular bin 201 for the screw rod 105 and the fixing rod 106 to pass through, and the screw holes 204 on the rectangular bins 201 of the four sowing components 200 are respectively matched and sleeved on the outer peripheries of the first threaded portion 107, the second threaded portion 108, the third threaded portion 109 and the fourth threaded portion 110.

[0036] In the present technical solution, the sowing device includes a frame 100 and four sowing components 200. Four rollers 103 for moving are symmetrically installed on both sides of the frame 100. A film covering shaft 101 and a film pressing shaft 102 are also installed at the bottom of the frame 100. The film covering shaft 101 is provided with a ground film on the outer sleeve, and film pressing wheels are installed at both ends of the film pressing shaft 102 for pressing both sides of the ground film. The rotation directions of the rollers 103, the film covering shaft 101 and the film pressing shaft 102 are consistent. The frame 100 is provided with a notch 104 which passes through from the top to the bottom. The notch 104 is rectangular, and its length direction is perpendicular to the travel direction of the roller 103. A rotatable screw 105 and a fixed rod 106 are installed in the notch 104 along the length direction. Four sowing assemblies 200 are arranged on the outer sleeves of the screw 105 and the fixed rod 106. Each sowing assembly 200 includes a rectangular bin 201 and two prismatic bins 202. An opening for pouring seeds is arranged on the top of the rectangular bin 201. Two rectangular openings are arranged on both sides of the bottom of the rectangular bin 201. One of the prismatic bins 202 is provided with a hole for pouring seeds. Rectangular side wall openings, the rectangular side wall openings of the two prismatic bins 202 are connected to the two rectangular openings at the bottom of the rectangular bin 201 correspondingly, so that the two prismatic bins 202 are connected to the rectangular bin 201, and a sowing wheel 300 is installed in the middle of the two prismatic bins 202. The internal structure of the sowing wheel 300 is consistent with the prior art, and hollow rotating shafts 203 are arranged on both sides of the outside. The two ends of the rotating shaft 203 are rotatably connected to the bottom of the triangular side walls of the two prismatic bins 202, and the cavity of the prismatic bin 202 is connected to the inner cavity of the sowing wheel 300, which is convenient for seeds to enter the sowing wheel 300 from the seed storage bin for sowing. The two opposite side walls of the rectangular bin 201 are provided with mutually interpenetrating and parallel screw holes 204 and first through holes 205, wherein the screw holes 204 are for the screw rod 105 to penetrate, and the first through holes 205 are for the fixing rod 106 to movably penetrate, and the extending directions of the screw rod 105, the fixing rod 106, the screw holes 204, and the first through holes 205 are perpendicular to the traveling direction of the vehicle frame 100. The side walls extending from one end to the other end of the screw rod 105 are respectively provided with a first threaded portion 107, a second threaded portion 108, a third threaded portion 109, and a fourth threaded portion 110, wherein the first threaded portion 107 and the fourth threaded portion 110 have the same thread pitch and opposite rotation, and the second threaded portion 108 and the third threaded portion 109 have the same thread pitch and opposite rotation, and the threads in the screw holes 204 on the four sowing assemblies 200 are matched with the four threaded portions, respectively, so that the four sowing assemblies 200 are matched and sleeved outside the four threaded portions of the screw rod 105.During sowing, the seeds of sweet sorghum are placed in the seed storage bins located at the first threaded portion 107 and the third threaded portion 109, and the seeds of corn are placed in the seed storage bins located at the second threaded portion 108 and the fourth threaded portion 110, respectively. The motor 112 connected to the screw 105 is turned on to rotate the screw 105, driving the four sowing assemblies 200 to move closer or farther from each other, thereby adjusting the sowing row spacing. Through the special design of the screw 105, the distance between the four sowing assemblies 200 can always be kept consistent during adjustment, which is convenient and fast, thereby improving work efficiency. After adjusting the row spacing, tear off one end of the ground film and fix it to one end of the field, hold the handle 113 and push the frame 100 in the sowing direction, and complete the sowing work while the sowing wheel 300 rotates, and then compact and fix both sides of the ground film through the film pressing wheel, and complete the sowing and film covering work at one time. Using this sowing device is convenient and fast, and can effectively improve work efficiency.

[0037] In another technical solution, the first threaded portion 107 and the second threaded portion 108 have the same thread rotation direction, the third threaded portion 109 and the fourth threaded portion 110 have the same thread rotation direction, and the thread pitch of the first threaded portion 107 and the fourth threaded portion 110 is twice the thread pitch of the second threaded portion 108 and the third threaded portion 109. In this technical solution, the first threaded portion 107 and the fourth threaded portion 110, the second threaded portion 108 and the third threaded portion 109 have the same thread pitch and opposite rotation directions, and the thread pitch of the first threaded portion 107 is twice the thread pitch of the second threaded portion 108. The screw 105 rotates so that the spacing between the four sowing assemblies 200 can be synchronously increased or decreased, which is convenient for synchronously adjusting the sowing row spacing, easy to operate, and saves time and effort.

[0038] In another technical solution, two hollow rotating shafts 203 are symmetrically arranged on both sides of the seeding wheel 300, and the free ends of the two rotating shafts 203 are respectively borne through the side walls of the two prismatic bins 202 that are close to each other, and sleeves 206 are coaxially installed in the two rotating shafts 203, and a plurality of support rods 207 are connected between the outer wall of the sleeve 206 and the inner wall of the rotating shaft 203, and the two ends of the sleeve 206 are respectively borne through the side walls of the two prismatic bins 202 that are far away from each other, and an insertion rod 208 is movably sleeved in the sleeve 206, and the two ends of the insertion rod 208 respectively pass through the sleeve 206 and are fixedly connected to the side walls of the notch 104. In this technical solution, the seeding wheel 300 and the two prismatic bins 202 are interconnected through a hollow rotating shaft 203, so that the seeds in the seed storage bin enter the seeding wheel 300 through the rotating shaft 203, and then the seeds are sown by the seeding teeth on the outer periphery of the seeding wheel 300. The internal structure of the seeding wheel 300 is consistent with the public reports in the prior art. By providing a sleeve 206 and a plug 208, the seeding assembly 200 moves along the plug 208 as the screw 105 rotates, and the screw 105, the fixed rod 106 and the plug 208 form a triangle, which improves the stability of the structure and ensures that the seeding assembly 200 moves smoothly.

[0039] <Example 1>

[0040] A test field was selected, and intercropping was carried out using the sowing device of the present invention. 450 kg·hm -2 of urea and 375 kg·hm -2 The sweet sorghum and corn were intercropped at a row ratio of 2:2, covered with film, and watered once every 20-30 days. From the sowing day to the waxy stage, the film was dripped for a total of 5 times, with a total irrigation volume of 3750 m 3 ·hm -2 The row spacing of sweet sorghum is 400×600 mm, the row spacing is 120 mm, and the planting density is 1.67×10 5 Hole·hm -2 The corn row spacing is 400×600 mm, the plant spacing is 205 mm, and the planting density is 7.75×10 4 Hole·hm -2 .

[0041] <Comparative Example 1>

[0042] The experimental field area with the same conditions as in Example 1 was selected, and intercropping was carried out using the sowing device of the present invention. 450 kg·hm -2 of urea and 375 kg·hm -2DAP was applied to sow sweet sorghum, mulch film was applied, and water was applied. Water was dripped under the film every 20-30 days. From the sowing day to the wax maturity stage, water was dripped under the film for a total of 5 times, with a total irrigation volume of 3750m 3 ·hm -2 The row spacing of sweet sorghum is 400×600 mm, the row spacing is 120 mm, and the planting density is 1.67×10 5 Hole·hm -2 .

[0043] <Comparative Example 2>

[0044] The experimental field area with the same conditions as in Example 1 was selected, and intercropping was carried out using the sowing device of the present invention. 450 kg·hm -2 of urea and 375 kg·hm -2 The corn was sown with diammonium phosphate, covered with film, and watered. Water was dripped under the film every 20-30 days. From the sowing day to the wax maturity stage, water was dripped under the film for a total of 5 times, with a total irrigation volume of 3750 m 3 ·hm -2 The row spacing of corn is 400×600 mm, the plant spacing is 205 mm, and the planting density is 7.75×10 4 Hole·hm -2 .

[0045] <Production Comparison>

[0046] During the harvest period, the crops in the test fields of Example 2 and Comparative Examples 1-2 were harvested, and the yields were counted and compared. The comparison results are shown in Table 1.

[0047] Table 1

[0048] Sweet sorghum yield / kg Corn yield / kg Total output / kg Example 1 7352 8654 16006 Comparative Example 1 5680 — 5680 Comparative Example 2 — 6150 6150

[0049] The comparison results show that, compared with Comparative Examples 1 and 2, the intercropping method of the present invention in Example 1 not only effectively improves the land utilization rate, but also increases the yield of sweet sorghum and corn, thereby increasing the ecological and social benefits.

[0050] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A sweet sorghum and corn intercropping device, characterized in that: include: A frame, a film-coating shaft, a film-pressing shaft, and four rollers are arranged at the bottom thereof, a ground film is sleeved on the film-coating shaft, film-pressing wheels are arranged at both ends of the film-pressing shaft, a through notch is also opened on the frame, a screw and a fixing rod are installed in parallel in the notch, the screw is composed of a first threaded portion, a second threaded portion, a third threaded portion, and a fourth threaded portion, the second threaded portion and the third threaded portion located in the middle of the screw are respectively provided with threads with the same pitch and symmetrical rotation direction, the first threaded portion and the fourth threaded portion located at both ends of the screw are respectively provided with threads with the same pitch and symmetrical rotation direction, sprockets are arranged at both ends of the screw, the two sprockets are respectively connected to the driving wheels of the motor through chains, and a handle is also arranged on the top of the frame; Four sowing components, each of which is provided with a seed storage bin and a sowing wheel, the seed storage bin includes a rectangular bin and two prismatic bins connected to the bottom of the rectangular bin on both sides, the sowing wheel is located between the two prismatic bins and connected to the bottoms of the two prismatic bins through a hollow rotating shaft, an opening is provided on the top of the rectangular bin, and through screw holes and a first through hole are provided on the opposite side walls of the rectangular bin for the screw rod and the fixing rod to pass through, and the screw holes on the rectangular bins of the four sowing components are respectively matched and sleeved on the outer peripheries of the first threaded portion, the second threaded portion, the third threaded portion and the fourth threaded portion; Two hollow rotating shafts are symmetrically arranged on both sides of the seeding wheel, and the free ends of the two rotating shafts are respectively borne through the side walls of the two prismatic bins that are close to each other, and sleeves are coaxially installed in the two rotating shafts, and multiple support rods are connected between the outer wall of the sleeve and the inner wall of the rotating shaft. The two ends of the sleeve are respectively borne through the side walls of the two prismatic bins that are far away from each other, and an insertion rod is movably sleeved in the sleeve, and the two ends of the insertion rod respectively pass through the sleeve and are fixedly connected to the side walls of the notch.

2. The sweet sorghum and corn intercropping device according to claim 1, characterized in that: The first threaded portion and the second threaded portion have the same thread rotation direction, the third threaded portion and the fourth threaded portion have the same thread rotation direction, and the thread pitch of the first threaded portion and the fourth threaded portion is twice the thread pitch of the second threaded portion and the third threaded portion.

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