After sowing of melon vegetables, attention should be paid to strengthening heat preservation, warming and moisturizing management, combined with heating, multi-layer covering and other measures (such as adding plastic film, small arch sheds, night cover insulation materials, greenhouse heating, etc.), so that the temperature and ground temperature can be maintained. In the optimum temperature range of 25 °C ~ 30 °C, the minimum night temperature of 15 °C ~ 18 °C above, the night temperature of 18 °C ~ 20 °C, prompting the emergence of seedlings and Miao Qi Miao as soon as possible. This period is mainly to promote the emergence of seedlings, management is based on the principle of insulation, warming, generally do not conduct ventilation. In this condition, generally 3 to 5 days can be emerged.
The temperature of the seedbed is the main factor affecting the emergence of seedlings. The soil temperature is too low and rotten seeds are prone to occur. Therefore, in the cold season sowing, it is best to use heating hotbeds, electric hotbeds, or temporary heating and other measures to promote rapid emergence, Miao Qi Miao.
First, temperature management
Hypocotyls are very sensitive to temperature and humidity when the seedlings are newly emerged. Under high temperature and high humidity, the hypocotyls will rapidly elongate to form leggy seedlings. The management goal after the emergence of the seedlings is to promote the seedling hypocotyls to grow thickly and the rapid development of the root system. When the seedlings emerge out of balance (the cotyledon tops out of the soil surface), the ventilation and cooling should be timely, and the humidity should be maintained at about 25°C during the day and 15 at night. °C. After the first true leaf is unfolded, the nighttime temperature can be suitably reduced by 1° C. to 2° C. to form a large temperature difference between day and night, promoting the growth of thick seedlings and differentiation of female flowers, and preventing excessive elongation of the hypocotyls. In case of rainy weather, the temperature should be properly reduced. After cotyledon flattening, management aims at promoting true leaf growth, flower bud differentiation, and cultivating strong seedlings. The temperature control is mainly controlled by controlling the timing of the air release and the amount of air discharge, and the time of uncovering the heat-insulating material. It is necessary to gradually increase the amount of air release and the time of air release as the temperature rises, and the amount and position of the air release should be as uniform as possible in the seedling bed so that the growth of seedlings is consistent. The part of the vent is the first middle or top wind, and then transition to both sides or bottom. According to the changes in the weather and seedbed temperature changes to control the amount of air release and ventilation site. About 10 days before planting, the seedlings enter the hardening period.
Second, moisture management
When raising seedlings in winter or early spring, watering too much or too large in the early stage can easily lower the temperature of the seedbed, which is not conducive to the growth of the seedlings. If the water is watered at a high temperature, the seedlings can easily become leggy. Therefore, the bottom water must be poured before planting so as to meet the water requirement for the growth of seedlings and early seedlings. Minimize watering or even watering during nursery. In the early stage of nursery, it is also possible to use the method of covering the moist soil to adjust the moisture and reduce the contradiction of the ground temperature. In the middle and later stages of raising seedlings, with the increase of temperature, the amount of water evaporation increases, and the method of covering the fluvo-aquic soil can no longer meet the water requirement of the seedlings. At this time, a high-temperature sunny morning can be selected to be sprayed with a watering can. Under normal circumstances do not warm irrigation, so as not to reduce the temperature or cause leggy seedlings. The principle of watering at the seedling stage is “no cloudy days, sunny days, no afternoon pouring, and morning pouringâ€. Seedlings should be seeded with water before sub-seedling, and seedling water should be poured when sub-seedlings are planted; watering should also be carried out on the first day before cut-off seedlings.
Third, lighting management
In the nursery of protected land, the light conditions of the seedlings are not only related to the weather, but also related to the uncovering and management of the opaque coverings in the protected land. These managements not only affect the light, but also influence the temperature in the protected land. Seedling stage should be as much as possible so that the seedbed to receive more sunlight in order to improve the ground temperature of the seedbed, generally early cover late. Adequate light during the nursery period is conducive to the cultivation of strong seedlings. Therefore, in the winter and early spring when the low-temperature and low-light season is growing seedlings, the seedlings should be allowed to receive more sunlight as much as possible. In addition to early release of opaque cover to cover the extension of the lighting time, management should always clean the transparent cover film to increase the amount of light transmission. The film is preferably dripless. On cloudy days, opaque coverings should also be uncovered, and in the rain and snow days, opaque coverings should be uncovered for a short period of time. If we encounter successive shades, rain, and snow, the seedlings will mainly consume nutrients in their own bodies, and they will easily cause seedlings to grow yellow and grow weak, and even yellow wilt will die. Therefore, in the event of such weather, opaque coverings should be uncovered as much as possible. Seedlings receive sunlight and even take supplements or put reflective films (aluminized polyester film) on the northern side of the greenhouse.
Soil loosening can occur when soil moisture is excessive, compaction occurs, or in winter and early spring to improve the ground temperature of the nursery bed. The loose soil can be used bamboo sticks or 8 small wire to make a small lotus root, loosen or loosen the topsoil, breaking the depth of the principle of not hurting the root. The ripping soil can be carried out once after the seedlings are flushed out, when two cotyledons are flattened and when two true leaves are present. In order to promote the normal growth of seedlings, foliar fertilization may be performed according to seedling growth conditions and fertility of the nursery bed. Generally, foliar fertilizers can be applied to two true leaves and three to four pre-planting treatments. The foliar fertilizers are mainly 0.2% urea and 0.3% potassium dihydrogen phosphate or other nutrient-type foliar fertilizers. Foliar fertilization usually takes place after 3 pm.
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