The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. The proportions and "parts" mentioned in the present invention are all based on weight if there is no special mark.
 In order to increase the yield of sea millet seedlings, improve stress resistance, and increase the content of effective nutrients, the present invention provides an attachment base support device for breeding improved sea millet varieties and a method for breeding improved sea millet varieties, with specific technical solutions as follows:
 A kind of attachment base supporting device for sea millet breeding, comprising connecting rope 1, suspension rope 2, pulley 3 and support frame 4, such as figure 1 As shown, the connecting rope is wound on two pulleys to form a closed loop. As the pulley rotates, the two parallel connecting ropes move in opposite directions respectively; the pulley is fixed on the raft frame in the sea area. The supporting frame is a cuboid without an upper cover, and the size is 80cm×20cm×15cm-120cm×60cm×25cm. The body wall of the support frame is covered with small holes, which serve to turn the support frame into a water-permeable frame body and ensure the fluidity of seawater in the frame. The diameter of the small holes is 0.5-1 cm. The outer surface of the upper edge of the support frame is provided with perforations, and the suspension rope is passed through multiple perforations along the edge in turn, and fixed on the perforations, and then the two ends of the suspension rope are respectively fixed on two parallel Connect the rope. In order to increase stability, a plurality of suspension ropes are arranged in parallel on each support frame, and the suspension ropes are preferably polyethylene ropes with a diameter of ≥0.8 cm.
 When in use, the support frame is fixedly connected to the connecting rope through the hanging rope. Since the two ends of the same hanging rope are respectively connected to two parallel connecting ropes, when the pulley rotates, the two parallel connecting ropes face the opposite direction. Move, drive the two ends of suspension rope to move toward opposite direction, thereby can shorten the distance between support frame and connecting rope, and support frame floats out of the sea. At this time, fix the attachment base with the seedlings in the support frame, move the pulley in the opposite direction, and drive the hanging rope to gradually return to its original position, thereby extending the distance between the support frame and the connecting rope. The support frame enters below the sea surface, and the seedlings begin to Sea farming. During the breeding process, the depth of the water layer where the support frame is located can be adjusted at any time, so that the seedlings on the attachment base are always under the light conditions suitable for growth.
 As a preferred embodiment, the plane where the pulley and the connecting rope are located is perpendicular to the horizontal plane, and when the suspension rope is fixed to the connection rope, it is tilted toward the inside to reduce the risk of the support frame tipping over when the two ends of the suspension rope move in opposite directions.
 In order to ensure that sea millet is in the best light conditions, it is necessary to place the support frame in a suitable water layer. In the cultivation method of this embodiment, the optimum water layer depth is 3 meters below sea level, but the sea level will be affected by the rising tide. The ebb tide changes, so the position of the supporting frame needs to be moved up and down with the change of sea level. In this embodiment, the attachment base support device further includes a controller and an underwater illuminance meter, and the underwater illuminance meter is installed on the support frame for measuring the depth of the water layer. The controller is used to receive the water layer depth actually measured by the underwater illuminance meter, compare it with the set water layer depth, make a judgment, and control the rotation direction of the pulley. Since the positions of the pulley and the connecting rope are fixed, the position of the support frame is adjusted by rotating the pulley so that the support frame is always at a suitable water layer depth.
 By using the device of this embodiment, the support frame can be raised or lowered conveniently. When the support frame floats out of the water, the work of observing the growth of the seedlings, washing the attachment base or harvesting algae can be carried out, thereby avoiding the cultivation personnel from entering Operation in seawater is convenient for daily management of sea millet farming.
 The present embodiment also provides a method for breeding improved varieties of sea millet, the steps are:
 1) Preparation of attachment base: The attachment base is a rectangular cement block with a size of 25cm×15cm×3cm-35cm×25cm×8cm, preferably 30cm×20cm×5cm, with a diameter of 0.8-1.5cm in the middle For the round hole, the side of the cement block attached to the seedlings is roughened with a hair brush to facilitate the attachment of the sea millet seedlings.
 The attachment base is soaked in fresh water for 7 days before use, during which the water needs to be changed 2-3 times, then soaked in seawater for 7 days, during which the water needs to be changed 2-3 times, and finally potassium permanganate (mass percentage concentration 1ppm) disinfection treatment.
2) Sea millet with seedlings: When the temperature in the sea area is 12°C, start to collect sea millet for planting vegetables, select a single female parent with tall plants, strong algae, many reproductive supports and good maturity, and select some samples, and use calcium acetate method to determine its alginate content.
 The seedling pool is pre-sterilized, and the bottom of the pool is spread with an attachment base, and then put into seawater, the water depth is not less than 50cm. Rinse the selected sea millet with high algin content and put it into the seedling pond, mark the corresponding attachment base, and fix it with falling stones to prevent the sea millet from being trapped in the seedling pond. move in. Running water culture to prolong the survival time of vegetables in the workshop.
 In the process of picking seedlings, the light is controlled at 3000-10000lx, the water temperature is at 20-22 ℃, and the salinity is not lower than 25‰; the nutrient element NO 3 -N content is 2-4 g/m 3 、PO 4 -P content is 0.2-0.4 g/m 3. Check the attached seedling density every 2 days, and the attached seedling density reaches 5-10 plants/cm 2 , pick out the vegetables. The seedlings are kept in the workshop for 20-25 days temporarily. The conditions for temporary cultivation are: the light is not higher than 30000lx, the water temperature is not higher than 20°C, the salinity is not lower than 25‰, the content of soluble inorganic nitrogen is 15-20 μmol/L, and the soluble inorganic nitrogen content is 15-20 μmol/L. The content of inorganic phosphorus is 0.3-0.5μmol/L, and the water flow rate is not higher than 0.8m/s to prevent seedlings from falling due to erosion. After the length reaches 5-8mm, it is transported to the sea for breeding.
 In order to prevent damage to the seedlings during transportation, choose to transport when the temperature is low in the morning and evening (the temperature is not higher than 25°C), and cover the attachment base with a wet cloth soaked in seawater to keep the seedlings in a moist state. If the transportation process is more than 1 hour, it is necessary to put the attachment base into an incubator and add an ice bottle for sealed transportation, and the temperature should be controlled at 13°C-20°C. .
 3) Mariculture: use the above-mentioned support device for the attachment base, turn the pulley to float the support frame out of the water, place the attachment base of the attached seedlings in the support frame, and use tie bars to pass through the round holes on the attachment base to fix the attachment base on the At the bottom of the plastic basket, reversely turn the pulley, and place the support frame together with the attachment base 3m below the sea surface. The distance between two adjacent attachment bases in the support frame is 4-6 cm, and the distance between the four sides of the attachment base and the side wall of the support frame is 8-12 cm, so as to ensure that the seedlings have enough growth space.
 During the sea culture process, the support frame is regularly lifted out of the water to observe the growth of the seedlings, and the attachment base is regularly washed to prevent the attachment of algae until the seedlings grow into adults. And in the breeding process, the rotation of the pulley is controlled artificially or by the controller, so that the support frame is always located at the depth of the water layer suitable for the growth of sea millet seedlings.
 4) In May of the following year, when the seawater temperature is stable above 10°C, take out the sea millet cultivated in the support frame, select a single plant with strong growth potential, many reproductive supports and good maturity, and measure the content of alginate. A single plant with high gum content is used for planting vegetables, and it is bred according to the method of raising seedlings in the first year.
 5) In May of the third year, select a single plant with strong growth potential, more reproductive tracts, good maturity, and high algin content from the sea millet cultivated in the second year, and breed according to the seedling raising method of the first year .
 6) In May of the fourth year, from the sea millet cultivated in the third year, select a single plant with strong growth potential, more reproductive tracts, good maturity, and high algin content to grow vegetables, and breed according to the seedling raising method of the first year .
 7) After more than 3 generations of germplasm breeding and screening, an excellent variety with vigorous growth and high algin content was finally selected
 Through the method of this example to cultivate sea millet, the continuous three generations of self-breeding and breeding of excellent individual plants of sea millet have been realized. From the selection of the initial high-quality vegetable, the growth potential is vigorous, the reproductive support is large and the maturity is good, and the algin content is high. Several factors such as high screening of individual plants are beneficial to determine stable genetic traits. After more than 3 generations of breeding and screening, the stress-resistant fine varieties with high algin content and large individuals that can be stably inherited were finally selected.
 By adopting the method for aquaculture of sea millet in the present embodiment, the adverse effect on sea millet seedlings caused by drying out of the intertidal zone is overcome. Combined with the attachment base support device, the support frame can be easily lifted out of the water surface to observe the growth of the seedlings, wash the attachment base, etc., which is convenient for the management and follow-up observation of the sea millet seedlings. The controller controls the support frame to always be at a suitable water depth, which is conducive to the robust growth of sea millet. Therefore, the improved seed breeding method of this embodiment is highly operable, simple and suitable for large-scale implementation.
 The above embodiments are only some of several preferred implementation modes of the present invention. It should be pointed out that the present invention is not limited to the above embodiments; Modifications, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed in the present invention.