In the past, people often cultivated in open fields in spring, summer and autumn. Cowpea cultivated in the open field is often the time when all kinds of vegetables are in sufficient supply. Although it is welcomed by the market, the planting benefit is not high. In recent years, cowpea has been cultivated in cold shed in early spring in many places, and good yield and economic benefits have been achieved.
First, the sowing date of cold shed cultivation
Because the heat preservation effect of cold shed cultivation is not as good as that of warm shed, it is only suitable for use when the temperature is not too low in spring. Cowpea takes about 60~70 days from sowing to harvesting. Sowing in the north in mid-February, the first batch of pods can be harvested in mid-April, which is more than 1 month earlier than the harvesting time of cowpeas cultivated in the open field in spring. At this time, the supply of vegetables in the market is not sufficient, and the economic benefit is naturally much higher than that of open cultivation. If you want to plant cowpeas in a cold shed, you must first find out what requirements cowpeas have for the environment.
Second, cowpea's requirements for growth environment
One of the biggest influences on cowpea growth is temperature, and the other is light.
1, cowpea's requirement for temperature
Cowpea likes to be heat-resistant but not frost-resistant. The lowest temperature of seed germination is 8 ~ 65438 02℃, the optimum growth temperature is 25~30℃, and the optimum plant growth temperature is 20~25℃. When the temperature is lower than 10℃, the growth of plants will be inhibited, and when it is lower than 5℃, it will be frozen. When the temperature reaches above 35℃, a large number of flowers and fruits will drop, pods will become shorter and deformed, and the taste will be rough and the quality will be poor. In addition, high temperature will also lead to premature senescence of cowpea plants.
2. cowpea's requirements for light
Cowpea likes strong light, especially during flowering and pod setting. Insufficient light will cause flowers and pods to fall. During this period, it is best to keep the light intensity at 40000 lux.
Third, cowpea cultivation and management techniques in greenhouse
1, variety selection
Variety selection is very important if you want to grow cowpeas well in a cold shed. High yield, early maturity, disease resistance, low temperature tolerance and weak light tolerance are all basic conditions; It would be better if it has the advantages of strong growth, less branches, less aging and long harvest period.
At present, the better varieties are Fengjiangyou, RT Mart, Fengjian 555, Cowpea Tezao 30, Zhijian Cuilv, Zhijian 90, Zhijian Telong 80 and Zaofeng 60, all of which have better benefits in cold shed in spring. Manufacturers can choose suitable varieties according to local consumption habits.
2. Sowing and raising seedlings
(1), sowing method
In the open field cultivation of cowpea, the direct seeding method is adopted. For cold shed cultivation, direct seeding can also be used for seedling transplantation. The method of seedling raising and transplanting is to raise seedlings in the greenhouse now, and then transplant the seedlings into the cold shed. Because the temperature in the cold shed can be ignored when raising seedlings, only the temperature in the cold shed can meet the requirements when planting, which will make the sowing time about 20 days earlier than that of direct seeding cultivation and the harvesting time about 20 days earlier. Therefore, if conditions permit, it is best to adopt the cultivation mode of raising seedlings first and then transplanting and planting.
(2) seed treatment
Cowpea seeds should be treated before sowing.
Seed soaking: seed soaking with 0.0 1%~0.03% ammonium molybdate solution 10 minute.
Accelerating germination: After soaking seeds, accelerate germination. First, wrap the seeds with wet cotton cloth and put them in a constant temperature environment of 25~30℃ to accelerate germination. After about 2~3 days, cowpea seeds will germinate.
(3), seedbed preparation
Although the root system of cowpea is developed, its regeneration ability is weak. In order to reduce the damage to the root system during transplanting, it is best to raise seedlings in nutrient pots. The nutrient soil can be vegetable garden soil without bean crops, and the vegetable garden soil is mixed with decomposed organic fertilizer at a ratio of 4:1.
Fill the nutrient bowl with nutrient soil, put it neatly on the nursery bed, and then water it once to make it permeable. When the water seeps down, you can sow.
(4), sowing
According to the germination of cowpea seeds, put 3~4 seeds in each pot, less seeds with good germination potential and more seeds with poor germination potential. After sowing, cover the soil with a thickness of about 2 cm, and cover the soil evenly. In order to ensure the required temperature at seedling stage, the seedbed must be covered with plastic film.
After cowpea was sown, the temperature in the shed was kept at 25~30℃ during the day and at 15~ 18℃ at night. Cowpea can germinate in 5~6 days.
(5), seedling management
Cowpea enters the stage of seedling management after emergence. The seedling stage of cowpea is about 15~20 days. The key of seedling management is to control temperature. It can be unearthed about 7 days after sowing. At this time, ventilation should be used to eliminate moisture, and the temperature in the shed should be lowered appropriately to prevent the seedlings from growing white. The daytime temperature can be controlled at 20℃, and the nighttime temperature should be kept above 15℃.
After the cotyledons of seedlings are unfolded, in order to promote the growth of roots, stems and leaves and the differentiation of flower buds, the temperature in the shed should be raised appropriately at this time, and it should be above 15℃ during the day and at night. Cowpea seedling raising should ensure that the humidity of nutrient soil is about 60%. When the nutrient soil is found to be dry, it should be watered at noon on a sunny day and watered thoroughly every time. When the first true leaves of the seedlings appear, they can be transplanted and planted.
3. Transplanting and planting
(1), plot selection
Cowpea does not require much soil, so it is best to plant it in fertile sandy loam. Cowpea should avoid continuous cropping, because continuous cropping will destroy the balance of soil, inhibit the activity and development of rhizobia, affect the yield of cowpea, and even aggravate the pests and diseases during cultivation. Cowpea is best rotated with non-leguminous vegetables, and the rotation time is 2~3 years.
(2) Fertilization and soil preparation
Before planting, fertilization and soil preparation should be carried out first. In order to obtain high yield, more base fertilizer must be applied to the planting plots, otherwise, flowers and pods will fall off due to soil malnutrition, which will lead to a large reduction in production. For medium fertility soil, 2500~3500 kg of fully decomposed manure and 0/5 ~ 20 kg of calcium superphosphate/kloc-are applied per mu. Deep tillage after fertilization is beneficial to increase soil temperature and promote root development. Ploughing depth should be greater than 25 cm. After harrowing, make a frame with the width of 1. 1 m in the north-south direction, and make the retroperitoneum in the frame.
(3) Planting
Water cowpea seedlings the day before planting to reduce root damage caused by bumping against clods in the process of taking seedlings, which will affect the late emergence delay. Planting should be done on a sunny day. First, according to the row spacing of 50-60 cm and the plant spacing of 40-45 cm, plant holes are punched on the border.
Gently pinch the nutrient bowl to separate the soil from the nutrient bowl, take the cowpea seedlings out of the nutrient bowl together with the clods, put them into the planting hole, and then fill the planting hole with soil. In order to promote the slow growth of seedlings, planting water should be poured in the planting bed once after planting.
(4) Slow seedling management
The temperature in the shed at seedling stage is high, which should be kept at 25~28℃ during the day. Under normal circumstances, the shed film should be sealed and not ventilated. However, when the temperature exceeds 32℃ during the day, it can be ventilated for a short time to prevent the seedlings from baking at high temperature; The temperature at night is kept between15 and 20℃. In this way, after about 3~5 days, the slow seedling is over.
4. Field management after field planting
After the seedling is delayed, it enters the field management stage. There are two stages from seedling delay to harvest: vine pulling stage and pod setting stage.
(1), rattan management
The vine-pulling period is the period from slow seedling to flowering, which takes about 25~30 days.
① temperature management
After the seedling is delayed, the temperature in the greenhouse should be reduced appropriately, and the seedlings should be crouched to prevent the seedlings from growing white. The temperature in the shed is kept at about 20℃ during the day and at about 65438 05℃ at night. After 5~7 days, gradually increase the temperature in the shed, so that the daytime temperature reaches about 22℃ and the nighttime temperature remains at about 65438 08℃.
(2), hanging vines
During the vine-pulling period of cowpea, another important job is to hang vines in time. Because cowpea is a vine, it needs to be entangled by other objects during its growth. Therefore, when the cowpea plant grows to about 20 cm, it is necessary to hang the vine with nylon rope. Hanging vines is not only beneficial to the growth of cowpea, but also convenient for future management and picking.
First, tie one end of the nylon rope to the greenhouse beam or iron wire directly above the vine. After hanging, the length of the rope should be slightly surplus to prevent managers from pulling seedlings because the rope is too tight when walking in the field. After the lanyard is tied, insert the lanyard into the soil 5~7 cm away from the vine with a small wooden stick, so that it will automatically wind on the lanyard with the elongation of the vine of cowpea.
③ Water and fertilizer.
Cowpea doesn't need much fertilizer and water before flowering and pod setting. If there is too much fertilizer and water at this stage, the plant will grow too vigorously, and the flowering and pod-bearing parts will move up, resulting in empty vines in the middle and lower parts of the plant, reduced yield and even premature senescence of the plant. During this period, the management focus is to control water and fertilizer, conserve moisture and squat seedlings, and inhibit the vigorous growth of stems and leaves.
Before flowering, the vines need to be watered once, combined with watering and topdressing once. For fields with medium fertility, diammonium phosphate 15 ~ 20kg should be applied topdressing per mu to promote vine pulling. From then on to before flowering, watering should be controlled to promote the development of cowpea from vegetative growth to reproductive growth.
(2) management of pod setting period
When the bud on the plant is open, it enters the management stage of pod-setting stage. Pod setting period is the period from cowpea flowering to harvest, which usually takes about 20 days. Pod setting stage is also the stage when cowpea changes from vegetative growth to both vegetative growth and reproductive growth.
① temperature management
After cowpea blooms, the temperature in the shed is slightly higher than that in the vine-pulling stage. The temperature is controlled at about 25℃ during the day and 65438 08℃ at night. At this stage, if the greenhouse temperature is lower than 15℃ or higher than 30℃, it will be unfavorable for cowpea to blossom and pod, and when the temperature exceeds 35℃, it will also cause a large number of cowpea to drop flowers and pods. Therefore, pay close attention to the temperature changes in the shed at noon on sunny days, and ventilate and cool down in time when the temperature exceeds 30℃.
Cowpea grows its first inflorescence from the 5th to 7th section of the main vine. On top of the first inflorescence, each node has an inflorescence, in addition, there will be inflorescences with side branches at the first 1 ~ 2 nodes. Generally speaking, a vine can produce more than 20 inflorescences, and every other inflorescence can produce 5~ 10 florets. Although cowpea has many flowers, the pod setting rate is very low, accounting for only 20%~30% of the flowering amount, and most flowers can't pod; Although some pods have been shaped, they will also fall off in the middle stage of development.
In addition to temperature, falling flowers and pods are also related to factors such as too much or too little water, malnutrition and insufficient light. Therefore, in order to improve the yield of cowpea in cold shed, other factors should be managed well.
② Lighting management
Cowpea is a light-loving plant, especially in the pod-setting period, insufficient light will affect flowering and pod-setting, so it is necessary to clean the greenhouse film frequently to maintain sufficient light to reduce the occurrence of falling flowers and pods.
③ Pruning
Reasonable pruning is also one of the measures to ensure adequate nutrition of flower clips, reduce flower drop and pod drop, and increase cowpea yield. Pruning is divided into three steps:
The first step is to remove all the side branches growing under the first inflorescence to ensure the main stem is strong; The second part is to leave 2~3 leaves for the side branches above the first inflorescence to pick the core and wrap the side branches on the lanyard; The last part is to top the main vine when it grows to 2~2.3 meters high, to control the upward growth of the plant and promote the formation of flower buds on the lower lateral branches. Pruning operation can greatly reduce nutrient consumption and promote nutrient supply for flowering and pod setting.
(4) watering and fertilizing
Cowpea should keep dry flowers and wet pods at the pod-setting stage, and water control should be the main method at the initial flowering stage. If there is too much water, plants will grow too vigorously, consume more nutrients, and make buds underdeveloped or not bloom.
After the tender pod of the first inflorescence is elongated, the plant gradually enters the vigorous growth period, at this time, it is necessary to grow stems and leaves one after another and blossom and pod, so it needs a lot of water and nutrients. At this time, water once, water once. Potassium fertilizer is beneficial to improve pod quality, so more potassium fertilizer should be applied this time, and the compound fertilizer with the ratio of nitrogen, phosphorus and potassium 16:8: 16 should be topdressing in the plot with medium fertility. Ensure that the soil is dry and wet at the peak of pod setting, and water it immediately if it is dry.
Step 5 harvest
Cowpea is harvested in batches and stages, and harvested when it is mature. Generally, 12~ 15 days after flowering is the best time for harvesting, and cowpeas must not be harvested too late, otherwise the pods will easily age. It not only affects the quality of cowpea, but also affects the flowering and pod setting of cowpea in the later stage.
It is best to harvest before 10 in the morning or after 4 pm. Cowpea is a raceme with 2~5 pairs of flowers per inflorescence. After the first pair of pods were harvested, the second pair of buds began to develop. When harvesting, the action should be light, so as not to hurt or knock off the flower buds on the inflorescence, so as to increase the number of pods and increase the yield. It can be picked once every 4~5 days in the early harvest period and once every 1~2 days in the whole pod period.
Cowpea has a long harvest period, and it can be harvested continuously for 40~50 days if it is well managed. Especially for this kind of crops cultivated in greenhouse, because the market price is relatively high, the longer the harvest period, the higher the economic benefit. At the same time, growers are also required to strengthen the management of cowpeas during harvest.
(1) water and fertilizer
At the harvest time of cowpea, the temperature in the greenhouse became higher, the plants grew faster, and the number of cowpea gradually increased, which required sufficient nutrition and water supply. 45% compound fertilizer (1 5-15) is applied1times every 6-8 days after harvest, and 8- 10 kg fertilizer is applied per mu, with medium fertility.
(2), to prevent premature aging
The high temperature in the shed at the late harvest stage will accelerate the premature senescence of cowpea plants. In the late stage of harvest, the plants can be supplemented with nutrition, and 0.2% potassium dihydrogen phosphate or urea solution can be sprayed through foliar fertilizer.
(3) Replace old leaves
In the late stage of pod setting, old leaves are easy to appear in the lower part of the plant. Removing old leaves in time can not only strengthen ventilation and light transmission, but also save nutrient consumption and improve later yield.
Cowpea was cultivated in cold shed in early spring, although it was harvested in advance and put on the market, in order to get higher yield of cowpea, the management cost was much higher than that in the open field.