Temperature requirements for drying net in laver culture process

The thallus appeared in late autumn and early winter and disappeared until the end of the following spring. Therefore, the bacteria adapt to lower temperature. For example, Porphyra yezoensis can grow at 0.5 ~ 65438 08℃; Porphyra haitanensis has a high temperature. When the water temperature in the sea area exceeds 20℃, the leaves of laver will rot.

Porphyra is a common edible red algae. It is popular for its fresh taste, good nutrition and special mushroom flavor. Modern medicine has proved that laver does have the effect of preventing and treating arteriosclerosis and hypertension.

1. Porphyra yezoensis ecology

Temperature: The phyllodes appear in late autumn and early winter and disappear until the end of the following spring. Therefore, the bacteria adapt to lower temperature. For example, Porphyra yezoensis can grow at 0.5 ~ 65438 08℃; Porphyra haitanensis has a high temperature. When the sea water temperature exceeds 20℃, laver leaves rot.

Illumination: Porphyra grows in the middle high tide line and is a kind of red algae that likes light. The light intensity is below 5000 m candle, and the growth is accelerated with the increase of light intensity; If it exceeds 5000 m candle, photosynthesis will be inhibited. Light for 3 ~ 9 hours every day. Drying resistance: the leaves of laver are very resistant to drying. Porphyra growing on rocks and net curtains can live normally after low tide even if it becomes brittle after being dried by the sun. Generally, it is better to dry it for 2 hours at high tide.

Requirements for current, specific gravity and nutrients: Porphyra likes to grow in fertile sea areas with gentle tidal current and certain wind and waves, and can live in seawater with a specific gravity of1.010 ~1.025. In the sea area lacking nitrogen fertilizer, laver is dull in color and has slender leaves.

Morphology and examination of filamentous bodies: After the fruiting spores are released, they can extend out of the germination tube when they encounter calcareous matrix, dissolve calcareous substances and drill into them to grow into filamentous bodies.

According to the morphological characteristics of filamentous body, it can be divided into filamentous algal filament stage, expanded algal filament stage and shell spore formation stage. Porphyra filaments growing in shells can only be observed under a microscope after decalcification. Commonly used decalcification solutions are: ① 5 ~ 7% acetic acid seawater solution; ② Bellani solution: 1% nitric acid 4 parts; 3 parts of 85-95% alcohol; 3 parts of 0.5% chromic acid.

Culture room: the culture room should face south, with skylight as the main lighting method. The skylight area accounts for about 1/3 ~ 1/2 of the area of the aquaculture pond, and some side windows are opened to facilitate ventilation. Indoor light should be uniform, avoid direct light, and it is best to use ground glass. Seedling production

Aquaculture pond: rectangular is better. The flat pond is only 20 ~ 30 cm deep; The depth of hanging pond is 60 ~ 70 cm. The newly built pool must be fully soaked to remove alkalinity before it can be used. If it is cultivated in a small area, wooden pots and plastic pots can also be used as culture containers.

Sedimentation tank: used for settling and storing seawater. In order to purify seawater, it is best to precipitate 1 week in the dark.

Attachment group: Filamentous attachment group, using clam and oyster shell. After washing, the holes on it can be hung on the opposite rope. Wash water and change water: 1 week After picking seedlings, you can clean the floating mud and diatoms on the shells with a soft brush and change water. After half a month, wash and change water. In summer, seawater evaporation is large and salinity increases, so some fresh water must be added to the aquaculture pond to adjust the proportion.

Temperature and light control: Filaments can withstand high temperature, but they are cultivated indoors. In midsummer, open the window to keep the same wind and stir the pool water to cool down. Porphyra yezoensis is below 28℃ and Porphyra haitanensis is below 29℃. At the initial stage of filamentous growth, from April to May, the light intensity was controlled at about 65,438+500 m candle. When the filament is covered by the shell, it can be reduced to 1000 m candle in June; In late July, the light was adjusted to 500 m candle. In the process of expanding cell formation, the illumination time should be shortened to 8 ~ 10 hours per day, and the black curtain should be used to shade the light, which is beneficial to the formation and maturation of endospores.

Fertilization: Filamentous growth needs fertilization. Mainly nitrogen fertilizer and phosphorus fertilizer. Different stages of filamentous growth require different fertilizers. When the fruit spores drill into the shell, fertilization begins, with nitrogen 5ppm and phosphorus 1 ~ 2 ppm. In the late stage of filamentous algae, nitrogen is 10 ~ 5 ppm, and phosphorus is 2 ~ 5 ppm. In the early stage of filamentous algae expansion, phosphorus fertilizer increased to 10 ~ 15 ppm, and nitrogen decreased to 5 ppm. At the later stage of algal filament expansion, the dosage of phosphate fertilizer increased to 15 ~ 20 ppm, and the nitrogen decreased to 2ppm.

Two. cultivation techniques

1. A curtain for picking seedlings

Bamboo curtain: Cut waste bamboo into bamboo pieces and weave a curtain with a length of 3m and a width of1.5m.. Every 40 curtains 1.80 square meters, or 0.067 hectares. Although the cost of bamboo curtain is low, it is very heavy and it is not convenient to pick seedlings by hand.

Vinylon curtain: firm, light, good adhesion, but high cost. Firstly, the vinylon monofilament is made into a rope with a diameter of 3 ~ 4 mm, and then woven into a net curtain. Raising 1 ha laver requires 337.5 Jin of vinylon rope. Both bamboo curtains and vinylon curtains are newly woven, so they must be soaked in clear water for 20 ~ 30 days to remove toxic substances. Otherwise, the effect of attaching seedlings will be affected.

2. The specifications of the net curtain

Grid: it can be divided into diamond net and volleyball net formats. Specifications are 1.2× 5m, 1.5× 2m, 2× 2m, etc. have

1.5× 12m, 2× 8m, etc.

Strip curtain: the advantage is that it is convenient to collect laver, and the specifications are 0.75× 2m, 1× 2m, etc.

Breeding method:

Column type: wooden stakes or bamboo stakes are fixed in the intertidal zone suitable for raising laver, and the net curtain does not fluctuate with the tide.

Semi-floating raft type: the whole raft frame can float on the water at high tide, and manna will stand on the beach with short legs after low tide. Because the net curtain has a certain drying time, miscellaneous algae are not easy to grow, which is beneficial to the emergence and growth of laver, so it is widely used.

Full floating raft: this method is similar to kelp culture, and the net curtain has been immersed in seawater. Miscellaneous algae are easy to reproduce, which is not conducive to the emergence and growth of laver, so it is not widely used now.

3. Sea area selection

The sea area for cultivating laver should be selected according to the orientation, wind and waves, sediment and tidal current.

Wind and wave and orientation: Spore propagation and thallus growth of laver shell need certain wind and wave. On the premise of ensuring the safety of the raft frame, the sea area with northwest wind and northeast wind is selected in winter and spring. The inner bay with small wind and waves and poor tidal current is not suitable for large-scale cultivation of laver.

Sediment and slope: In order to facilitate piling, drifting, management and harvesting, it is best to choose sediment bottom, sand bottom or hard mud bottom. Poor soft mud or flat gravel, uneven gravel matrix, inconvenient operation, affecting the safety of breeding curtain frame. Beach surface of intertidal zone in aquaculture area

The slope is small, which can increase the breeding area.

Water quality and tidal current: clean seawater in aquaculture area is better. Too much turbidity will affect the seedling density and the quality of laver because of more sediments. The tidal current is smooth, the laver seedlings have good adhesion, fast growth, long culture cycle and many harvest times. In the slow tidal waters, the growth and yield of laver are poor. Selection of tidal level: It is very important to choose a suitable tidal level for cultivating laver. The tidal level is too high, laver has few attached seedlings, late emergence, slow growth and low yield per unit area; The low tide level, many harmful organisms, is not conducive to semi-artificial seedling collection, easy to attach miscellaneous algae, premature aging, inconvenient management and harvesting. There are two ways to choose tide level: one is based on manna time. Can be used at high tide and 2-4.5 hours of nectar time (35 cm away from the beach). The other is the dry tide line based on the small tide. The last row of breeding net curtains is placed below the tidal level, and the tidal level is dry for 1 ~ 2 days in winter, and the last row of net curtains is placed in the mid-tidal area 2/3 above the tidal level. The former can be measured on the spot, and the latter can be based on the lowest tide line on August 23 of the lunar calendar. Porphyra haitanensis has strong drought resistance, and the beach position can be appropriately higher; Porphyra yezoensis has poor drought resistance, and the breeding tide level is lower.

4. Daily management during the growth period

After the low tide during the day, managers must patrol the sea, especially in the event of a storm. Inspection of curtain frame: the loose and damaged curtain frame is ligated and repaired, and the bamboo curtain and net curtain squeezed by wind and waves are rearranged; Repair or replace curtain feet; Correct the uneven curtain frame to keep it on a flat surface. Check the fixing device: check whether the bamboo, wooden stakes and stone rafters move, whether the piles and rafters are worn or broken, and replace and reinforce them in time when problems are found. Adjust the row spacing: after a period of impact of wind, waves and tidal current, the ropes are extended, and the curtains in adjacent rows are prone to collision or overturning. Tighten the rafters and keep the original row spacing. Clean air and clean the net curtain: there are often 8 ~ 9 winds along the coast during the cultivation stage, and early seedlings will be attacked by typhoons. You should listen to the weather forecast every day, pay attention to the weather changes and take precautions. The wind and waves are too strong, and there is a danger of pulling out piles and destroying the frame. You can lift the curtain rack to a sheltered place, but keep the curtains moist and wait until the wind passes before moving into the sea. Measures such as strengthening curtain frame or relaxing floating raft can also be taken to prevent wind and waves. Sludge deposition in seedling emergence and culture stage is easy to cause difficulty in germination and rot of laver, so it is necessary to wash curtains frequently at high tide to keep them clean.

Three. disease control

White rot: leaves turn red first, then white, rot and fall off. The disease occurred in11~ 65438+February, which was mainly caused by insufficient light and poor tidal current. As long as the net curtain is properly thinned, it can be moved to a place with a gentle trend.

Red rot: red rust spots appear on leaves, which gradually expand and rot. Caused by pythium. Hang a curtain on the dew. The disease is mainly caused by seawater precipitation and insufficient dark treatment, and is caused by microorganisms. The shell surface is yellow circular spots, which appear from the edge of the shell and gradually spread to the center.

Macular disease: treat the macula with low specific gravity seawater (1.005) for 2-5 days, or all fresh water will turn the macula into white spots; Or soak in 2ppm potassium permanganate solution 15 hours.

Green spot disease: at first, laver has bright green circular spots, and soon the center turns white and perforated, which usually occurs when the water temperature is high and the rainfall is heavy. It can increase the nectar time of prevention and control.

Mud red disease: this disease occurs in the period of high water temperature and is caused by microorganisms. The shell surface is muddy red, sticky and smelly. Treatment method: try to reduce the indoor temperature and keep the same wind well; At the same time, wash the shells with110000 bleaching powder solution or soak them in 1.438+05 low-gravity seawater for 2 days.

Harm of fish and waterfowl: If fish such as Sparus macrocephalus, crucian carp and sea duck swallow laver, they can be driven away by netting and shooting.

Harm of miscellaneous algae: Enteromorpha, Ulva, diatom, etc. Adhesion to the net curtain affects the growth and quality of laver. You can wash the curtains in manna or every 4 ~ 5 days. If there are too many attached algae, the net curtain can be taken ashore 1 day before going into the sea.