What should be paid attention to in seedling management of spring cucumber in open field?

(1) Spring cucumber in the open field should be selected with low temperature tolerance, low node position of female flower, dense melon yard, early maturity and good cohesiveness. Due to different consumption habits in different regions, its main varieties are also different. North China likes prickly cucumbers, and the commonly used varieties are Guonong 1 1, Guonong 13 and Jin Yan. Be sure to read the variety description carefully before use.

(2) Under normal circumstances, spring cucumber in the open field needs to be raised in facilities, and the main ways of raising seedlings are sunshine bed, improved sunshine bed, sunlight greenhouse and plastic shed. Among them, the greenhouse seedling raising equipment is simple, the investment is small, the technology is simple and easy to popularize, it is convenient for seedling training and cultivating strong seedlings, and it can be planted early and marketed early. But at present, seedling raising in solar greenhouse is more popular.

(3) In order to prevent cucumber seeds from carrying bacteria, seeds are often soaked in warm soup. The soaking time is shortened with the increase of soaking temperature. The imbibition time is about 10 hour at 35℃, 12 hour at 25 ~ 30℃, 18 hour at 10℃ and 24 hours at10℃. After soaking seeds, put them at 25 ~ 30℃ to accelerate germination, and sow when most seeds turn white. At present, the widely popularized method is to soak seeds in the dark of 1∶ 1 for 3 ~ 4 days with the mixed solution of 3% potassium nitrate and 3% potassium dihydrogen phosphate, which can obviously improve the germination rate of seeds at low temperature (9 ~ 13℃) (/kloc respectively).

In addition, PEG osmotic adjustment treatment (250g/L PEG solution treatment 12 hours), dry heat treatment (75℃ treatment for 24 hours) and pre-imbibition treatment (15℃ pre-imbibition treatment for 26 hours) can improve seed vigor. 2% allicin can significantly promote the radicle elongation of cucumber seeds.

(4) In order to accelerate the emergence of cucumber seedlings and enhance the adaptability of seedlings to low temperature, embryos can be exercised at low temperature. The specific method is to wrap the newly broken seeds with cloth and put them at-1℃ ~-2℃ low temperature 12 hours, and then at 18 ~ 22℃ low temperature 12 hours. If this treatment is repeated for several days, the elongation of buds can be controlled at low temperature, the consumption of nutrients can be saved, and the colloidal properties of protoplasts can be changed. High temperature promotes the decomposition of nutrients and maintains the vitality of seeds. During the exercise, the seeds should be kept moist. When the seeds are put back to high temperature, the cloth bag can be opened until the seeds are thawed. Cucumber seeds can be exercised 2 ~ 3 times.

(5) The suitable physiological seedling age of spring cucumber is 4 leaves 1 heart. It usually takes 35 to 40 days. The sowing date of each place can be calculated according to the frost period and the specific conditions of each place. The sowing amount depends on the 1000-grain weight of seeds and the number of seedlings required per unit area, and the required seed amount per unit area is 2 ~ 3 kg/ha.

(6) Spring cucumber seedlings are in low temperature season, so two key periods should be paid attention to in temperature management. First, sow until 60% ~ 70% of seedlings emerge, which needs about 28℃. Mastering higher temperature is conducive to promoting seedling emergence and reducing nutrient consumption; Second, cotyledons spread out until the true leaves are exposed, so we should control the lower temperature and the excessive elongation of hypocotyls to prevent the occurrence of damping-off. Attention should also be paid to seedling exercise in the late stage of seedling raising to improve the cold resistance of seedlings and adapt to the environmental conditions after planting. Thirdly, we should pay attention to the change of ground temperature in seedbed, because the ground temperature in seedling stage is closely related to the germination and emergence of cucumber seeds and the growth and development of seedlings. The suitable ground temperature of cucumber seedlings is 25℃ the day before emergence, 20℃ at night, 22℃ the day after emergence and 65438 08℃ at night. In the process of seedling raising, the ground temperature is affected by the air temperature. When the lowest temperature of seedbed is 10℃, the ground temperature of 10 cm can be maintained above 12 ~ 13℃. Therefore, in order to maintain the suitable ground temperature for cucumber seedling, it is necessary to take soil heating measures, such as electric heating wire heating, brewing raw materials heating, heating by fire resistance and so on.

(7) Seedling raising in winter and spring is in the season of short sunshine and strong light, and weak seedlings are easy to appear because of less photosynthetic products. Therefore, it is necessary to strive for light as much as possible, uncover the film as soon as possible, cover it as late as possible and increase the light time without freezing the seedlings; Keep the film clean and increase the light transmittance; On cloudy days, the scattered light should also be uncovered under the permitted conditions; After the snowy day, the snow should be cleaned and exposed in time.

(8) Before sowing, after watering the seedbed, the seedlings are generally not watered, and some moist soil can be covered when the seedlings are dry. If the nursery is raised in a nutrient bowl, the nutrient soil is easy to dry because of its small size and low water holding capacity, so it should be watered according to the specific situation, and the water temperature should not be too low. Water should be done before noon when the temperature is high, and spray water with a watering can. If the seedlings are weak and need topdressing, you can use 0. 1% urea and 0. 1% potassium dihydrogen phosphate to water or spray fertilizer on the leaves.

(9) When cracks appear in the seedbed, wet soil should be covered in time; After cloudy days and snow, you should also uncover the grass to look for sunshine. It suddenly clears up after continuous cloudy and snowy days, and the grass can't be exposed at once. Let the seedlings see the light gradually to prevent the seedlings from flashing. If the leaves wilt slightly after uncovered, they should be "returned to the shed" in time, uncovered after recovery, and transferred to normal management when the seedlings are suitable for 1 ~ 2 days. Remove the mulch in rainy days, but prevent rainwater from flooding into the seedbed. In case of cooling down or strong cold current after rain, it should be covered with warmth or take temporary heating measures.