Fund Project: Efficient cultivation technology of ice vegetables in northern plastic greenhouses

Fund Project: Efficient cultivation technology of ice vegetables in northern plastic greenhouses

Fund Project: Shaanxi Provincial Key R&D Program (2019 TSLNY01-04); Northwest A&F University 2020 Experimental Demonstration Station Science and Technology Innovation and Achievement Transformation Project (TGZX2020-13)

Wang Dianwei and others

The scientific name of ice vegetables is ice leaf day flower, also known as ice flower, African ice grass, etc., is a genus of flowers in the family Cinnamomyceae, named because of the large number of ice crystalline particles on the back of its leaves and stems. Under saline conditions, icecress can secrete excess salt absorbed by the roots through the salt glands into salt sac cells with a diameter of about 2 mm on the surface of the stem and leaf. Experiments have shown that 667 m2 ice vegetables can take away about 200 kg of salt from the soil on average throughout the year, so ice vegetables are ideal for repairing saline soils. At the same time, ice vegetables also have high nutritional health care functions, rich in natural low sodium salts, antacid substances (folic acid, pantothenic acid, etc.), polyhydroxy compounds (pine alcohol, inositol, manzanol, etc.), flavonoids (retinol, etc.), with hypoglycemia, cholesterol, improve liver function, prevent arteriosclerosis, anti-tumor, enhance immunity and other effects. Ice vegetables mainly eat young leaves and young stems, can be mixed with fruit salad, blanched water cold mix, hot stir-fry, etc., the taste is tender, smooth, slightly salty, flavor chic, is a high-level ingredient in French cuisine, in France, South Korea, Japan and other countries as a healthy vegetable to eat, in recent years also introduced to China, as an emerging health vegetable began to be commercially planted in China. At present, the ice vegetable industry in Shandong, Zhejiang, Yunnan, Hubei, Shanghai, Tianjin, Shenzhen and other places has formed a certain scale, with a market price of 8 to 20 yuan per kg, considerable economic benefits and broad market prospects, but in the northwest region, large-scale planting has not yet been formed.

In view of the market demand for ice vegetables and the potential value of soil improvement for continuous cropping in greenhouses, ice vegetables have good development potential in Guanzhong region of Shaanxi Province. In the spring and autumn of 2018-2020, the author's research group conducted 2 a (year) 5 consecutive stubble cultivation experiments in the plastic greenhouse in Yangling, Shaanxi Province, summarizing the key technical links of the cultivation of ice vegetables in plastic greenhouses, in order to provide a reference for the cultivation and cultivation of ice vegetables in the northern region.

1 Biological characteristics of ice vegetables

1.1 Morphological characteristics of ice vegetables

Icecress is a one- and two-year succulent herb, with a developed whisker root system, the main root groups are distributed in the soil layer of 5 to 10 cm, not tolerant of moisture, this property suggests that the number of watering should be paid attention to when cultivating icecress; the stem is cylindrical, the early upright, the middle and late period creeping, the stem and leaves are covered with a large number of ice crystal particles, the stem base is tightly hugged, heart-shaped, almost every axillary bud can become a side branch, the side branches can be extracted to produce more branches, forming a larger nutrient system; leaves are opposite, the stem spiral distribution, full edge, emerald green color, Flattened hypertrophy, densely covered with epidermal salt bubble cells; flower apical or axillary, head-shaped inflorescence, petals filamentous and shiny; flowering period of 1 month, summer opening, due to the presence of inbred incompatibility, ice vegetables need to be pollinated by different plants; after flowering, the formation of capsules, each capsule contains seeds 100 to 130 grains, and the 1,000 grains weigh 0.15 to 0.18 g.

1.2 Requirements for environmental conditions of ice vegetables

Originating from arid areas such as the Namib Desert in South Africa, ice vegetables have the characteristics of drought tolerance, flood avoidance and salinity tolerance, and can grow normally under the conditions of salinity equivalent to seawater (salinity 35‰), and prefer well-drained sandy loam soils. The growth temperature is 5 ~ 30 °C, the optimal temperature is 15 ~ 25 °C, the minimum can tolerate -5 °C cold; the temperature exceeds 30 °C, the leaves are thin, the stem and leaf ice crystalline particles are significantly reduced, and the quality is reduced, so the cultivation of greenhouse ice vegetables should be arranged from September to June of the following year. Ice vegetables like light and are also shade tolerant, and can grow under the illuminance conditions of 3000 to 14 000 lx, but long-term weak light will lead to thin leaves, short branches and poor quality of ice vegetables; on the contrary, the light is too strong, the leaf edges become red, and the ice crystal particles are reduced, affecting the commerciality. Ice vegetables are cultivated in greenhouses in the northern region, and there is no need for light adjustment.

2 Efficient cultivation techniques of ice vegetables

2.1 Stubble arrangement

Because ice vegetables are not heat-tolerant, production should make full use of the cold and cool months of the year, and try to avoid the high temperature season from June to August. The growth cycle of ice vegetables is up to 6 months, and the northern plastic greenhouses produce ice vegetables, and 2 stubbles can be arranged every year: (1) Spring and summer stubble: seedlings are bred in the first and middle of February using electric hotbeds, colonized in mid-to-late March, and harvested in mid-June; (2) Autumn and winter stubble: shading nets are set up in mid-to-late July to cool seedlings, colonized in late August, and harvested to early to mid-March of the following year.

2.2 Plot Selection

Sandy soil plots with loose soil, good air permeability, convenient drainage and irrigation, and no pollution such as heavy metals should be selected for planting, and low-lying and sticky soil plots should be avoided. Ice vegetables are salt-tolerant and alkali-resistant, and are also suitable for cultivation in facilities with severe secondary salinization.

2.3 Sowing seedlings

2.3.1 Varieties At present, most of the ice cabbage seeds used in production are wild species. There are very few ice vegetable cultivation species, Shouguang Dingjialou Vegetable Base has bred a new variety of ice vegetables suitable for cultivation in northern China", "ice grass", and Jiangsu Harvest Land Seed Industry has cultivated ice vegetable varieties such as large leaves, tooth leaves, and fern leaves.

2.3.2 Sowing New nursery trays, chassis and other utensils are selected; if it is an old nursery tray, it is best to disinfect with 0.3% to 0.5% potassium permanganate solution for 12 h to avoid the occurrence of standing blight and cause dead seedlings after colonization. 1 L seedling substrate can be mixed with 1 g carbendazim, stirred with water, and the substrate humidity reaches the degree of "kneading into a ball by hand, falling to the ground and spreading".

Sow new seeds that are full, mature, black and shiny, and free of pests and diseases. Icecres seeds are extremely small and do not require pre-sowing germination treatment. Put the ice cabbage seeds into origami, sow them in a 50-hole seedling tray with a good substrate by jittering, sow 2 to 3 seeds per hole, sow shallow, no more than 0.5 cm, spray the appropriate amount of water with a sprayer, and then sprinkle a thin layer of vermiculite to moisturize, which is conducive to the germination of ice vegetable seeds.

2.3.3 Seedling stage management The temperature at the seedling stage is controlled at 20~25 °C during the day and 15~20 °C at night. Winter and spring nursery seedbed temperature should not be too high, when the temperature is high, moderate ventilation and cooling, should be as far as possible to ensure the light time, to avoid long; summer and autumn seedlings should be set up with shade nets to cool down, to avoid strong light exposure.

During the emergence of seedlings, it is necessary to water in time, and the watering should be soaked or sprayed, and the irrigation should be avoided with large water to ensure that "when it is dry and wet, it will be watered thoroughly". Sowing for about 1 week, the seedlings can be produced intact. When the plant is too dense, remove the disease, weakness and seedlings in time. 30 days after sowing, the appropriate concentration of foliar fertilizer can be sprayed to ensure that the ice vegetable seedlings grow strongly.

The disease at the seedling stage of ice vegetables is mainly cataplexy, which is controlled by irrigation roots such as downy mildew hydrochloride. During the nursery period, the yarn net is built on the outside, and the yellow plate and blue plate are hung inside to prevent insects. 35 to 45 days after sowing, seedlings can colonize when they have 4 to 5 true leaves.

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2.4 Preparation before colonization

After the harvest of the former stubble crop, the ground is turned over and fertilized. General medium fertility soil, 667 m2 bio-organic fertilizer 800~1000 kg, nitrogen, phosphorus and potassium ternary compound fertilizer 40~50 kg. The amount of fertilizer can be adjusted according to the actual situation. After leveling the land, the smoke shed is selected from isopropylvir, bacillus qing, etc., and the amount of 667 m2 is 1 bag each.

Ice vegetables are drought-tolerant and not waterlogging-tolerant, and can be cultivated in a semi-high ridge manner, with a furrow width of 1.0-1.3 m, a ridge height of 15-20 cm, and a ridge bottom width of 70-90 cm. In order to improve the ground temperature, preserve moisture, reduce humidity, reduce manual pulling, and reduce muddy water contamination of ice vegetables, mulching film is required. After laying a drip irrigation belt in the center of each ridge, a 1.3 m wide silver-black double-sided mulch film is laid on top, with the silver side facing outward.

Before colonization, the seedlings are refined according to the weather conditions. 2 days before colonization, ice vegetables combined with watering, irrigation with downy mildew hydrochloride root (20 mL moldy hydrochloride to water 15 L), no watering on the day of colonization, so as not to scatter the lump.

2.5 Colonization

Spring and summer stubble ice vegetables, choose a sunny and windless morning colonization, autumn and winter stubble ice vegetables, choose afternoon or cloudy day colonization. Colonize 1 row of ice vegetables on each side of each ridge, the row spacing of ice vegetables is 30 cm×50 cm, and the colonization holes are opened on the mulch film, and 3200 to 3800 plants are colonized at 667 m2. When planting seedlings, place the soil seedlings in the center of the colonization hole, and then suppress them slightly after covering the soil to ensure that the root system and the soil are in close contact. The root lump of ice vegetable seedlings should be ensured to be intact, and the depth of colonization should be not exposed to the root lump; drip irrigation in time after colonization, and water the fixed root water thoroughly.

2.6 Field management

2.6.1 Temperature and light regulation In spring and summer cultivation, the temperature of 28 °C and above in the shed will lead to clusters of ice vegetables, small leaves, few ice crystal particles, and reduced commerciality. After April in The Guanzhong area, the temperature in the shed at noon will often exceed 28 °C, and it is necessary to ventilate and cool down and drain moisture in time.

Autumn and winter cultivation, especially after entering the late autumn, should do a good job of heat preservation, to avoid ice vegetables from frost damage; in the cold winter, should be covered with grass curtains, felt, etc. outside the greenhouse to keep warm, insulation materials should be uncovered early and covered late. Even in rain and snow, remove the cover so that the ice vegetables can accept scattered light. In cultivation, under normal temperature, it should be ensured that the ice vegetables are in full light conditions as much as possible.

2.6.2 Regulation of water fertilizer and salt After transplanting, attention should be paid to water control and squatting seedlings, and generally no watering is required within 1 week of colonization. Due to the drought tolerance of ice vegetables, when the leaves are slightly wilted, watering should be carried out, and watering should be thorough. Moderate watering is conducive to the increase in the yield of ice vegetables and the formation of ice crystal particles, but too much watering will lead to the saltiness of ice vegetables becoming lighter and less commercial, and the water holding capacity in the field is better than 70%.

Ice vegetables should be applied thin and diligently, and must not be too concentrated to avoid burning the roots. After one month of transplanting of ice vegetables, a balanced water-soluble fertilizer containing nitrogen, phosphorus and potassium can be applied once in combination with watering, and the dosage of 667 m2 is 5 to 10 kg. After that, for each harvest, it is necessary to topdress fertilizer with water in time, and 667 m2 topdress balanced water-soluble fertilizer 10~15 kg.

If the cultivation of ice vegetables is also used to improve the soil of the greenhouse of the facility, NaCl may not be added to the planting. If multiple stubbles of ice vegetables are planted continuously, it is necessary to supplement the appropriate amount of NaCl in combination with the degree of salinization of the indoor plot in the shed to increase the yield. Generally, the aqueous solution of NaCl is supplemented once a month after the seedlings are delayed. An aqueous solution of NaCl formulated with coarse salt or table salt, the first use of concentration 100 to 200 mmol · L-1 solution is filled with roots, and the concentration can be gradually increased to 300 to 400 mmol· L-1, if the next stubble is not planted with ice vegetables, salt supplementation should be stopped 1 to 2 months before harvest.

2.6.3 Plant management Iced vegetables grow upright in the early stage, creeping growth in the middle and late stages, in order to reduce the contamination of icecress stems and leaves by muddy water, cover cultivation is carried out. In order to reduce production costs, it is not recommended to build a frame for cultivation. Plant adjustment should be carried out in combination with harvesting, preferably dense branches, and reduce plant density to improve ventilation and light, which is conducive to the robustness of ice vegetable plants. Spring and summer stubble ice vegetables in June, due to excessive light will appear the tip of the leaf edge become purple red phenomenon, which is the sign of ice cauliflower buds before opening, in order to extend the harvest period, to remove the buds in time.

2.6.4 Disease and pest control There are fewer diseases of ice vegetables, the main disease is cataplexy, concentrated in the seedling stage and the early growth stage, mostly caused by high density, high humidity and poor ventilation, which can be effectively controlled by adding carbendazim, mulch film, irrigation with downy mildew hydrochloride before colonization, strengthening ventilation and dehumidification, etc., to minimize the use of pesticides. The main insect pests are snails, slugs, whiteflies, aphids and green worms. The greenhouse uses curtains, and the base lime sprinkled around the bottom of the shed can prevent snails and slugs from entering the shed, and the shed hangs yellow plates and blue plates, covering silver and black double-sided mulch film (silver side facing upwards) to reduce the harm of aphids.

2.7 Timely harvesting

Timely harvesting can avoid aging of young branches, promote the plant to grow more side branches, and prolong the harvest time. Harvesting usually takes place during times of the day when temperatures are low. Ice vegetables planted in mid-to-late March can be harvested in mid-to-late May, while ice vegetables planted at the end of August can be harvested in mid-to-late October. Ice vegetables grow long and have strong lateral branching ability, so they can be harvested multiple times, and can be harvested every 15 days during the peak growth period. Harvesting is carried out in conjunction with plant shaping, leaving axillary buds on the branches and cutting tender tips 10 to 12 cm long along the tip of the stem. Whether harvested or post-harvested, care should be taken to protect the ice crystal particles on the plant and tender tip. The harvested tip is placed in a foam box at the bottom where the ice pack is placed, separated by 2 layers of cotton cloth. Sold as soon as possible after harvesting, conditional can be cold chain transportation.