Method for mixed culture of summer seedlings and winter seedlings of kelp in northern sea area

Abstract

The invention relates to the field of seaweed cultivation, in particular to a kelp summer seedling and winter seedling mixed cultivation method for northern sea areas, which comprises the following steps: step 1, selecting a kelp mixed cultivation sea area, and erecting a large single raft frame in the cultivation sea area along the flow; step 2, summer seedling breeding: when the water temperature of the breeding area is lower than 20 DEG C and presents a continuous reduction trend, kelp seedlings are moved from the breeding room to a large single raft frame of a sea mixed breeding sea area for breeding; 3, winter seedling breeding: the water temperature of the breeding sea area is reduced to 15 DEG C, and kelp seedlings with rhizoids going deep into seedling ropes are moved from a breeding room to a large single raft frame of a sea mixed breeding sea area for breeding; 4, the seedlings are transplanted and cultured in the sea for 50-60 days, the first crop of kelp is harvested, culture continues for 15-20 days, and the second crop of kelp is harvested. The sea-tangle winter seedling cultivation work is carried out by utilizing the existing sea-tangle summer seedling cultivation sea area, a new raft frame does not need to be built, and the cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of kelp cultivation, in particular to a method for mixed cultivation of kelp summer seedlings and winter seedlings in northern sea areas. BACKGROUND

[0002] Kelp (Laminaria japonica Aresch) naturally grows in sub-frigid zone, and has a growth period of 2-3 years, a length of 2-6 m, and a width of 20-25 cm. Saccharina japonica Kelp cultivation practitioners have formed a "kelp raft type full artificial cultivation method" through years of exploration, which mainly includes steps such as cultivation area selection, raft setting, seedling temporary cultivation, cultivation, disease control and harvesting. According to the changes in characteristics, the cultivated commodity kelp is divided into four periods: juvenile period, concave-convex period, brittle tender period and thickening period. The main characteristics of the kelp in the juvenile period are thin and soft leaves, smoothness, and no concave-convex and edge part. The main characteristics of the kelp in the concave-convex period are thin and narrow leaves, and due to the inconsistent growth rate of each part, from the base, a series of two rows of concave-convex appear. From the brittle tender period, the concave-convex part of the kelp thallus pushes to the middle and upper part of the leaf, which has the characteristics of adult kelp, but the leaf is thin and tender. After the kelp enters the thickening period, the thickness increases significantly, the color becomes darker, and the longitudinal hand cannot be easily broken. Different production methods are developed according to different growth periods of kelp, forming a relatively complete technical system. According to the suspension mode of the seedling rope, it is generally divided into vertical cultivation, horizontal cultivation, and inclined horizontal cultivation.

[0003] The commodity kelp produced by the above method is traditionally referred to as 3 m or so thickening period large kelp, and the seed source is summer produced seedlings, which is called summer seedling cultivation, and the main production area in the north is generally from mid-October to May of the next year. In recent years, 50-60 cm concave-convex period small kelp has been welcomed by consumers because of its crisp and delicious fresh taste, and the market demand has increased year by year. The production methods of small kelp and large kelp are different, the main difference being that the cultivation density of small kelp is much larger than that of large kelp. In the kelp cultivation area in the north, generally 15 strains of large kelp are cultivated per 1 m seedling rope, while about 300 strains of small kelp are cultivated. Therefore, in order to produce small kelp with uniform growth and high yield, a special cultivation method is needed. Under the current realistic conditions of limited cultivation area, summer seedling cultivation alone cannot meet market demand, so at present, kelp production enterprises in the north carry out the second batch of kelp seedling cultivation at the end of October. Because most of the time is in the winter in the north, it is generally called winter seedling cultivation. It is relatively high in cost to separately set up raft frames in the sea area suitable for winter seedling cultivation. Cultivating large and small kelp in the same cultivation sea area will be a more economically beneficial way. Therefore, how to develop a method suitable for mixed cultivation of summer seedlings and winter seedlings in northern sea areas in order to reduce the cost of kelp production, produce high-quality kelp products, and meet market demand is an urgent problem to be solved by those skilled in the art. SUMMARY

[0004] In view of the problems in the prior art, the present application aims to provide a method suitable for mixed cultivation of summer seedlings and winter seedlings in northern sea areas, which can reduce the production cost of kelp, improve the production quality, and meet market demand.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas, comprising the following steps: Step 1: selecting a kelp mixed cultivation sea area, and erecting a large single raft in the cultivation sea area along the current; Step 2: summer seedling cultivation, when the water temperature in the cultivation area is lower than 20 ℃ and shows a continuous decreasing trend, moving the kelp seedlings from the cultivation room to the large single raft in the mixed cultivation sea area for cultivation; Step 3: winter seedling cultivation, when the water temperature in the cultivation sea area decreases to 15 ℃, moving the kelp seedlings with the false roots already deep into the seedling ropes from the cultivation room to the large single raft in the mixed cultivation sea area for cultivation; Step 4: transplanting the seedlings to the sea for cultivation for 50-60 days, harvesting the first batch of kelp, and continuing cultivation for 15-20 days to harvest the second batch of kelp.

[0006] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 1, the mixed cultivation sea area in the sea is divided into a first sea area and a second sea area according to the current speed during the big flood period, the low tide water depth, the transparency variation range, the nitrate content, and the bottom material, the current speed during the big flood period of the first sea area is 30-50 m / min, the low tide water depth is not less than 20 meters, the transparency variation range is 1-3 meters, the nitrate content is not less than 20 mg / m 3 , and the bottom material is flat mud or sand; the current speed during the big flood period of the second sea area is 10-30 m / min, the low tide water depth is 10-20 meters, the transparency variation range is 3-5 meters, the nitrate content is 5-20 mg / m 3 , and the bottom material is relatively hard sand or thin soft mud.

[0007] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 2, moving the kelp seedlings from the cultivation room to the mixed cultivation sea area in the sea comprises: Step 2-1: summer seedling transportation, according to the transportation time, the seedling transportation is divided into dry transportation and wet transportation, the transportation time of the dry transportation is less than 6 h, and the transportation time of the wet transportation is 6-12 h; Step 2-2: summer seedling temporary cultivation, adopting flat hanging, the seedling curtain with the kelp seedlings is cut into a length equal to the raft spacing of the large single raft, the two ends of the seedling curtain are fixed to the cables of the large single raft by using lifting ropes, a small sinker is added at the connection between the seedling ropes and the lifting ropes, the seedling ropes are spaced at 50 cm, and the seedlings are fertilized. Step 2-3: Summer seedling separation, after 25-30 days of temporary cultivation, the separation work is carried out, which is completed before the water temperature drops to 10℃, and the flat cultivation method is adopted, the rope distance is 80-100 cm in the first sea area, 50-80 cm in the second sea area, and the clamping seedling density is 14-16 plants / m; Step 2-4: Summer seedling growth, adjusting the strongest light intensity and raft buoyancy, and regularly fertilizing to make the summer seedling grow into a mature one.

[0008] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 2-1, the dry transport method adjusts the number of ice bottles at the bottom, middle and upper part of the foam box according to the number of seedling curtains and the size of the kelp seedlings in the foam box, the wet transport method is to tightly fill the gaps around the car with air-permeable water-retaining materials, and to lay the car bottom flat, one layer of air-permeable water-retaining materials and one layer of kelp seedling curtains in the car compartment, cover the car with a tarpaulin, and pour enough seawater to keep the temperature in the car below 15℃, the air-permeable water-retaining material is kelp grass, reed mat or felt.

[0009] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 2-2, the seedling fertilization adopts the method of hanging fertilizer bags, the fertilizer bags are hung in the middle of the seedling rope with an interval of 2 m, and each fertilizer bag weighs 200-250 g.

[0010] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 2-4, the light intensity before entering the thin and tender period, no flat part appears, the strongest light intensity of flat cultivation is not more than 20000-25000 lx, the water layer is kept at 80-100 cm, a small floating buoy with a buoyancy of 8 kg is added in the middle of the seedling rope, the standard of raft buoyancy during flat cultivation is that the floating ball is 1 / 2-1 / 3 exposed above water surface when flat, every 4-8 ropes add 1 floating buoy; the method of hanging bag fertilization is adopted, the amount of bag fertilization is 400-450 g per bag, and it is replaced every 3-5 days.

[0011] The method for mixed cultivation of summer seedlings and winter seedlings of kelp in northern sea areas described above, in step 3, the winter seedling growth adopts the method of one dragon, the kelp seedling rope is cut to twice the length between two floating buoys, the seedling ropes are overlapped, the overlapped ropes are fixed on thin bamboo poles or wooden poles with thin ropes, the two ends are tied with lifting ropes, the lifting ropes are tied on the cable, the strongest light intensity is adjusted to 25000-30000 lx, the water layer is kept at 80-100 cm, every 10-12 days, the water layer is reduced by 18-22 cm, until the strongest light intensity is reduced to 20000-25000 lx, a smaller 3 kg floating buoy is added on the cable to adjust, the floating ball is 1 / 2-1 / 3 exposed above water surface when flat.

[0012] The above-mentioned method for mixed cultivation of summer and winter kelp seedlings in northern sea areas involves adding fertilizer in step 3 using both pouring and hanging methods. Pouring fertilizer is done during low tide and current, from upwind and downstream, avoiding strong currents, rainy days, and periods of high winds and waves. A 1 / 300 concentration fertilizer is used, applied every 6-9 rows of large single-raft structures, following a standard spacing of 4-8 meters between rafts, 3-4 times a day. After 8 hours of fertilization, the nitrogen concentration is maintained at 25-30 mg / m³. 3 The concentration was optimized.

[0013] In the above-mentioned method for mixed cultivation of summer and winter kelp seedlings in northern sea areas, in step 3 and step 4, when harvesting the first batch of kelp, a large-hand shaking method is used for harvesting. First, untie one end of the seedling rope, lift the seedling rope so that the seedling leaves are drooping in the water, then hold the seedlings that meet the standards, reverse the seedling rope and shake it in the water to disperse the smaller seedlings, and then move your hand down to the middle and lower part of the seedlings and gently shake them in one direction to make the seedlings that meet the standards fall off.

[0014] The beneficial effects of this invention's method for mixed cultivation of summer and winter kelp seedlings in northern sea areas are: It utilizes existing summer kelp cultivation areas for winter kelp cultivation, eliminating the need for new rafts and saving costs. Simultaneously, it improves kelp growth conditions such as fertilization and sunlight exposure, which is beneficial for cultivating high-quality kelp products. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described below in conjunction with specific embodiments.

[0016] Example 1 A method for mixed cultivation of summer and winter kelp seedlings in northern sea areas includes the following steps.

[0017] Step 1: Select a marine mixed aquaculture area and set up a large single raft in the aquaculture area downstream.

[0018] Class I and Class II sea areas were selected as mixed aquaculture areas. The selection criteria are shown in Table 1, the sea area classification table below. Large single rafts were used, with the raft frame facing downstream.

[0019] Table 1: Classification of Sea Areas Step 2: Summer seedling cultivation. When the water temperature in the aquaculture area is below 20 ℃ and shows a continuous decreasing trend, the kelp seedlings are transferred from the cultivation room to the large single raft in the marine mixed aquaculture area for cultivation.

[0020] Cultivation methods before the tender summer seedling stage.

[0021] When the water temperature in the aquaculture area is below 20°C and shows a continuous decreasing trend, the seedlings can be transferred to the sea for further cultivation. This process mainly includes four steps: summer seedling transportation, temporary summer seedling rearing, summer seedling separation, and summer seedling growth.

[0022] 1. Summer seedling transportation is divided into two forms according to the transportation time.

[0023] First, for seedlings less than 6 hours old, a dry transport method is used. The number of ice packs at the bottom, middle, and top of the foam box is adjusted based on the number of seedling curtains and the size of the seedlings. A certain number of seedling curtains are placed in the foam box. Several ice packs are placed at the bottom, middle, and top of the box; if the seedlings are large, the number of ice packs is increased.

[0024] Secondly, for short-distance transportation of 6-12 hours, wet transport is adopted. When loading, the gaps around the truck are sealed with breathable and water-retaining materials such as kelp, reed mats or felt, and the bottom of the truck is laid flat. Then, a layer of breathable and water-retaining material is placed inside the truck bed, followed by a layer of kelp seedling curtains. Finally, the truck is sealed with tarpaulin and watered thoroughly to keep the temperature inside the truck below 15°C.

[0025] 2. Temporary rearing of summer seedlings.

[0026] The method of horizontal hanging is adopted, that is, the seedling curtain with kelp seedlings is disassembled into a length equal to the raft spacing of the large single raft frame. The two ends of the seedling curtain are fixed to the cable of the large single raft frame with hanging ropes. A small weight is added to each of the seedling ropes and hanging ropes of the seedling curtain, and the seedling ropes are spaced 50 cm apart.

[0027] Fertilizer bags are used to fertilize seedlings. The fertilizer bags are hung in the middle of the seedling rope, spaced 2 meters apart, with each fertilizer bag containing 200-250 g.

[0028] 3. Transplanting summer seedlings.

[0029] After the seedlings are temporarily raised at sea for 25-30 days, when they grow to 12-15 cm, they are transplanted. This process is completed before the water temperature drops to 10 ℃ and they are raised on the surface.

[0030] The seedling density is generally one seedling every 6-7 cm, or 14-16 seedlings / m. The rope spacing is 80-100 cm in Class I sea areas and 50-80 cm in Class II sea areas.

[0031] 4. Summer seedling cultivation: Adjust the strongest light intensity and raft buoyancy, and fertilize regularly to ensure the summer seedlings mature into timber.

[0032] 4.1 Light intensity.

[0033] Before entering the tender stage, before the flat part appears, the strongest light intensity for horizontal growth is 20,000-25,000 lx, and the water layer should generally be maintained at 80-100 cm. A small float with 8 kg buoyancy is added to the middle of the seedling rope.

[0034] 4.2 Float.

[0035] When raising fish horizontally, the standard for raft buoyancy should be such that 1 / 2 to 1 / 3 of the float is above the water surface when the current is horizontal. The standard is to add one float for every 4-8 ropes.

[0036] 4.3 Fertilization.

[0037] The method of applying fertilizer by hanging bags is adopted. The amount of fertilizer applied per bag is generally 400-450 g, and the bags are changed every 3-5 days, usually every 4 days.

[0038] Step 3: Winter seedling cultivation. When the water temperature in the aquaculture area drops to 15 ℃, the kelp seedlings with rhizomes that have penetrated deep into the seedling ropes are transferred from the cultivation room to a large single raft in the mixed aquaculture area for cultivation.

[0039] 1. Transportation of winter seedlings and seedlings.

[0040] The water temperature in the aquaculture area dropped to 15 ℃. The kelp seedlings grew to 0.5 cm, and their rhizoids had penetrated deep into the seedling ropes. They were transported to the aquaculture area using the same transportation method as the summer seedlings.

[0041] 2. Winter seedling cultivation.

[0042] The kelp seedlings are raised using a "one-stop" method, which involves cutting the kelp seedling ropes to twice the length between two floats, overlapping the seedling ropes, and using thin ropes or other binding materials to fix the overlapping ropes to a thin bamboo or wooden pole. Then, hanging ropes are attached to both ends and tied to a cable.

[0043] Adjust the strongest light intensity to 25,000-30,000 lx, and the water layer should generally be maintained at 80-100 cm. Every 10-12 days, lower the water layer by 18-22 cm, usually to 20 cm, until the strongest light intensity drops to 20,000-25,000 lx.

[0044] Based on the standard that the float is 1 / 2 to 1 / 3 above the water surface when in horizontal flow, add a small 3 kg float to the cable for adjustment.

[0045] Because the mixed cultivation area for winter and summer seedlings has a high stocking density, the kelp thallus absorbs fertilizer quickly and in large quantities. Therefore, fertilizer is added using both pouring and hanging methods, with the hanging method being the same as that used for summer seedling cultivation. Pouring fertilizer is done during calm tides and low currents, from upwind and downstream, avoiding strong currents, rainy days, and periods of high winds and waves. A 1 / 300 concentration of fertilizer is used, applied every 6-9 rows of large single-raft rafts, following a raft spacing of 4-8 meters, 3-4 times a day. The nitrogen concentration is maintained at 25-30 mg / m³ for at least 8 hours after fertilization. 3 The concentration was optimized.

[0046] Step 4: Transplant the seedlings into the sea and cultivate for 50-60 days. Harvest the first batch of kelp. Continue cultivation for 15-20 days and harvest the second batch of kelp.

[0047] Two harvests of winter seedlings are made. One harvest is made when the longest winter seedling reaches 50-60 cm in length. The harvesting method is "hand-shaking and pulling". First, untie one end of the seedling rope, lift the rope so that the seedling leaves are drooping in the water, then hold the seedlings that meet the standard, reverse the rope and shake it in the water to disperse the smaller seedlings. Then, move your hand down to the middle and lower part of the seedling and gently shake it in one direction to make the seedlings that meet the standard fall off.

[0048] Example 2 I. Sea Area Selection.

[0049] Select one type of sea area as the mixed aquaculture sea area.

[0050] II. Cultivation methods before the tender summer seedling stage.

[0051] When the water temperature in the aquaculture area is below 19°C, the summer seedlings are transferred to the sea for further cultivation.

[0052] 1. Transportation of summer seedlings.

[0053] Wet transport method is adopted. When loading, the gaps around the truck are sealed with breathable and water-retaining materials such as felt, and the bottom of the truck is laid flat. Then, a layer of breathable and water-retaining material is added, followed by a layer of seedling mat. Finally, the truck is sealed with tarpaulin and thoroughly watered with seawater to keep the temperature inside the truck below 13 ℃. The transport time is 1 hour.

[0054] 2. Temporary rearing of summer seedlings.

[0055] The seedlings are hung horizontally, with the seedling curtains cut to lengths equal to the spacing between the rafts of the large single-frame. Both ends are secured to the cable with ropes, and a small weight is added to each connection point between the seedling ropes and the cable. The seedling ropes are spaced 50 cm apart. Fertilizer is applied to the seedlings using hanging bags, with fertilizer bags hung in the middle of the seedling ropes at 2-meter intervals. Each fertilizer bag contains 200-250 g of fertilizer.

[0056] 3. Transplanting summer seedlings.

[0057] After being temporarily held at sea for 25 days, the seedlings will grow to 13-15 cm in length. They will then be transplanted and raised on a flat surface. The spacing between seedlings should be 6-7 cm between each seedling, with ropes spaced 80 cm apart.

[0058] 4. Summer seedling cultivation.

[0059] 4.1 Light intensity.

[0060] The water level is maintained at 80-100 cm, with an 8 kg buoyancy float in the middle.

[0061] 4.2 Number of floats.

[0062] Add one float for every four ropes.

[0063] 4.3 Fertilization.

[0064] When using the hanging bag fertilization method, the amount of fertilizer applied per bag is generally 400-450 g, and the bags should be replaced every 4-6 days.

[0065] III. Winter seedling cultivation.

[0066] 1. Transportation of winter seedlings and seedlings.

[0067] The water temperature in the aquaculture area dropped to 15 ℃. The kelp seedlings grew to 0.5 cm, and their rhizoids had penetrated deep into the seedling ropes. They were transported to the aquaculture area using the same transportation method as the summer seedlings.

[0068] 2. Winter seedling cultivation.

[0069] The kelp seedlings are cultivated using a "one-stop" method. The seedling ropes are cut to twice the length between two floats, overlapped, and secured with thin rope to a perforated wooden pole with a diameter of 1-2 cm. Suspension ropes, 80 cm long, are then attached to both ends and tied to a cable. Every 10-11 days, the ropes are lowered by 20 cm until the light intensity reaches 20,000-25,000 lx.

[0070] Based on the standard that the float is 1 / 2 to 1 / 3 above the water surface when in horizontal flow, add a small 3kg float to the cable for adjustment.

[0071] Fertilizer is added using both pouring and hanging methods, with hanging fertilization following the same procedures as the summer seedling cultivation method described above. Pouring fertilizer is done during calm, low-lying tides, from upwind and downstream, avoiding strong currents, rainy days, and periods of high winds and waves. A 1 / 300 concentration of fertilizer is used, applied every 9 rows of large single-raft rafts, following a 4-meter spacing, 3-4 times a day. The nitrogen concentration is maintained at 25-30 mg / m³ for at least 8 hours after fertilization. 3 The concentration was optimized.

[0072] IV. Gains

[0073] Two harvests of winter seedlings are made. One harvest is made when the longest winter seedling reaches 50-60 cm in length. The harvesting method is "hand-shaking and pulling". First, untie one end of the seedling rope, lift the rope so that the seedling leaves are drooping in the water, then hold the seedlings that meet the standard, reverse the rope and shake it in the water to disperse the smaller seedlings. Then, move your hand down to the middle and lower part of the seedling and gently shake it in one direction to make the seedlings that meet the standard fall off.

[0074] The first harvest yields 100 kg per mu, and the second harvest yields 150 kg per mu.

[0075] The above embodiments are merely illustrative of the structural concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for mixed cultivation of summer and winter kelp seedlings in northern sea areas, characterized in that, Includes the following steps: Step 1: Select a sea area for mixed seaweed farming and set up a large single raft in the sea area downstream; Step 2: Summer seedling cultivation. When the water temperature in the aquaculture area is below 20 ℃ and shows a continuous decreasing trend, the kelp seedlings are transferred from the cultivation room to the large single raft in the marine mixed aquaculture area for cultivation. Step 3: Winter seedling cultivation. When the water temperature in the aquaculture area drops to 15 ℃, the kelp seedlings with rhizomes that have penetrated deep into the seedling ropes are transferred from the cultivation room to the large single raft in the mixed marine aquaculture area for cultivation. Step 4: Transplant the seedlings into the sea and cultivate for 50-60 days. Harvest the first batch of kelp. Continue cultivation for 15-20 days and harvest the second batch of kelp.

2. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 1, characterized in that, In step 1, the marine mixed aquaculture area is divided into Class I and Class II marine areas based on the current velocity during the flood season, the low tide depth, the range of transparency variation, the nitrate and nitrogen content, and the seabed sediment. The Class I sea area has a high current velocity of 30-50 m / min during the flood season, a low tide depth of not less than 20 meters, a transparency range of 1-3 meters, and a nitrate nitrogen content of not less than 20 mg / m³. 3 The substrate is a flat mud or sandy bottom; The Class II sea areas described above have a high-tide current velocity of 10-30 m / min, a low-tide depth of 10-20 meters, a transparency range of 3-5 meters, and a nitrate nitrogen content of 5-20 mg / m³. 3 The bottom is a relatively hard sandy bottom and a loose mud bottom.

3. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 1, characterized in that, In step 2, transferring the kelp seedlings from the cultivation room to the marine mixed aquaculture area includes: Step 2-1: Summer seedling transportation. Based on the transportation time, seedling transportation is divided into dry transportation and wet transportation. The transportation time for dry transportation is less than 6 hours, and the transportation time for wet transportation is 6-12 hours. Step 2-2: Temporary rearing of summer seedlings. Using a flat hanging method, the seedling curtain with seaweed seedlings is disassembled into a length equal to the raft spacing of the large single-frame. The two ends of the seedling curtain are fixed to the cable of the large single-frame with hanging ropes. A small weight is added to each of the seedling ropes and hanging ropes of the seedling curtain. The seedling ropes are spaced 50 cm apart. Fertilize the seedlings. Steps 2-3: Summer seedling separation. After the summer seedlings have been temporarily raised for 25-30 days, the separation work should be carried out before the water temperature drops to 10℃. The horizontal rearing method is adopted. The rope spacing is 80-100 cm in Class I sea areas and 50-80 cm in Class II sea areas. The seedling density is 14-16 seedlings / m. Steps 2-4: Summer seedling cultivation, adjusting the strongest light intensity and raft buoyancy, and fertilizing regularly to ensure the summer seedlings mature into timber.

4. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 3, characterized in that, In step 2-1, the dry transport method adjusts the number of ice bottles at the bottom, middle, and top of the foam box according to the number of kelp seedling curtains and the size of the seedlings in the foam box. When loading the vehicle in the wet transport method, the gaps around the vehicle are sealed with breathable and water-retaining material and the bottom of the vehicle is laid flat. Inside the vehicle, there is a layer of breathable and water-retaining material and a layer of kelp seedling curtains. The vehicle is sealed with tarpaulin and water is poured in to keep the temperature inside the vehicle below 15°C. The breathable and water-retaining material is kelp grass, reed mats, or felt.

5. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 3, characterized in that, In step 2-2, seedling fertilization is carried out using hanging bag fertilization. The fertilizer bags are hung in the middle of the seedling rope, spaced 2 m apart, with each fertilizer bag containing 200-250 g.

6. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 3, characterized in that, In steps 2-4, before the seedling stage, the light intensity should not be too high, and the maximum light intensity for horizontal growth should not exceed 20,000-25,000 lx. The water layer should be maintained at 80-100 cm. A small float with a buoyancy of 8 kg should be added to the middle of the seedling rope. The standard for the buoyancy of the raft frame during horizontal cultivation is that the float is 1 / 2-1 / 3 above the water surface when the water is flowing horizontally. One float should be added for every 4-8 ropes. Fertilizer should be applied by hanging bags, with each bag containing 400-450 g of fertilizer, and the bags should be changed every 3-5 days.

7. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 1, characterized in that, In step 3, during the winter seedling cultivation, a single-line method is used. The kelp seedling rope is cut to twice the length between two floats, the seedling ropes are overlapped, and the overlapping ropes are fixed to a thin bamboo or wooden pole with thin rope. Suspension ropes are tied to both ends and attached to the cable. The strongest light intensity is adjusted to 25,000-30,000 lx, and the water layer is maintained at 80-100 cm. Every 10-12 days, the water layer is lowered by 18-22 cm until the strongest light intensity drops to 20,000-25,000 lx. Smaller 3 kg floats are added to the cable for adjustment, and the float is 1 / 2-1 / 3 above the water surface when in horizontal flow.

8. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 7, characterized in that, In step 3, fertilizer is added using both pouring and hanging methods. Pouring is carried out during calm, low-lying tides, from upwind and downstream, avoiding periods of strong currents, rainy days, and high winds and waves. A 1 / 300 concentration fertilizer is used, applied every 6-9 rows of single-span rafts, following a raft spacing of 4-8 m. This is done 3-4 times a day, maintaining a nitrogen concentration of 25-30 mg / m³ for 8 hours after application. 3 The concentration was optimized.

9. The method for mixed cultivation of summer and winter kelp seedlings in northern sea areas according to claim 1, characterized in that, In step 3 and step 4, when harvesting the first batch of kelp, the method of shaking and pulling is used for harvesting. First, untie one end of the seedling rope, lift the seedling rope so that the seedling leaves are drooping in the water, then hold the seedlings that meet the standards, reverse the seedling rope and swing it in the water to make the smaller seedlings spread out, and move your hand down to the middle and lower part of the seedlings and gently shake them in one direction to make the seedlings that meet the standards fall off.

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