In recent years, in the production process of watermelon in greenhouses in Dongtai City, the development of melons is often caused by changes in the cultivation environment, and malformations, cavities, cracked melons, glutinous deterioration, and umbilical rot are caused, resulting in reduction of production and quality, and prevention should be taken.
Commonly deformed are partial head melon, flat melon, pointed melon, gourd melon. The development of the lateral head melon is normal, and the other side is stagnant, which is caused by dysplasia of the factor house, uneven pollination and poor fertilization. The transverse diameter of the flat-shaped melon is larger than the longitudinal diameter, and the low-node female flower is easy to form when the temperature is low when sitting on the melon or sitting in the melon. The flower pedicle part of the beaked melon is thinned, the stalk is swollen, the nutrient supply is insufficient during the period of melon expansion, and it is easy to form when the high-section is sitting. The top of the gourd melon is close to the part of the flower pedicle, and is close to the fruit stem. It is a gourd-like part, which is caused by poor fertilization. Prevention and control measures: During the 2 to 4 true leaf stage of flower bud differentiation, the night temperature in the shed is kept above 13 °C, and the water and fertilizer supply is appropriate; the control of the melon node is selected, and the second to third female flowers are pollinated to keep the melon, and the plant grows. The potential is poor to delay the melon section, and vice versa; the artificially assisted pollination is carried out at 8-10 am on a sunny day, and the pollination amount is sufficient when the rainy days are postponed to 8-11, and the temperature is maintained at 20-30 °C during pollination. In order to improve pollen activity, if the female flower handle is bent and drooped the next day after pollination, the pollination is successful. If the fruit handle is still up or forward, it should be re-pollinated; the melon should be turned in time to correct the melon type; Supplement water and fertilizer, and increase the application of phosphorus and potassium fertilizer, it is best to use drip irrigation under the membrane.
The void is characterized by cracking of the melon and forming a gap cavity. In addition to the large fruit type itself, the low temperature and excessive nitrogen fertilizer cause prolonged sitting, which is easy to produce voids. Prevention and control measures: The greenhouse cultivation of watermelon should use small and medium fruit varieties, such as Xiaolan, Te Xiaofeng, early spring ruby, Zaojia (8424), etc.; during the sitting period, the shed temperature is maintained at 25~35°C during the day and 18~20 at night. °C, under low temperature or drought conditions, delay the sitting melon node; timely pruning, generally use three vine pruning; improve the ditch system to prevent continuous rainy weather, water and fertilizer meet the cause of plant growth; melon has eggs when the big melon, the first batch of melon One strain is selected.
The cracked melon is characterized by cracks from the cucurbit, and usually the thin varieties of the melon and the small fruit varieties are prone to occur. There are many reasons for this. One is that when the melon is inflated, it will encounter low temperature in the initial stage, and then it will be swollen rapidly after the development stops. The second is that the water is improperly watered during the harvesting period, so that the water absorption and evaporation are not balanced, causing the cracked melon. The third is that the development of drought at a certain stage of the melon is blocked, and suddenly the water is suddenly increased after a large amount of water to cause the cracked melon. Prevention and control measures: select suitable varieties; artificial pollination, try not to use hormone spray; the initial temperature of melon expansion is kept above 20 °C, watering in moderation, it is best to use drip irrigation under the membrane; melon can be removed from the greenhouse during high temperature and dry weather. The skirt film, retaining the top film, prohibiting flooding of the water in the field; melon bagging, minimizing collision during picking and transportation.
The deterioration of enamel is manifested as melon meat, especially the melon meat around the seed is water-stained, purple-red to brown, and ulcerated in severe cases. Mainly due to the rapid change of soil moisture, the root activity is reduced, and then the high temperature causes the melon to produce ethylene, causing abnormal breathing and deteriorating the enamel. When the plant is infected with cucumber green mottle mosaic virus, "water immersion" phenomenon also occurs. Prevention and control measures: Melons should avoid sun exposure, cover with straw when necessary; add organic fertilizer during the period of melon expansion, apply phosphorus and potassium fertilizer, timely watering or drip irrigation under the membrane; After the water is completely infiltrated, the temperature is increased, the soil moisture is drastically changed, and the root activity is prevented from being lowered. The poisonous insects, aphids, and whitefly are controlled in time, and the copper acetate is sprayed to prevent viral diseases.
Umbilical rot is mainly characterized by the depression of the top of the melon, which becomes dark brown. When the humidity is high, black mold is observed in the parasitic rot. It is easy to cause umbilical rot in the lack of water and calcium deficiency in the melon expansion period. Prevention and control measures: increase the application of decomposed organic fertilizer and superphosphate; cover the mulch to promote the protection of the sputum, balance the supply of water and fertilizer, drip irrigation under the membrane in the case of drought; spray 1% superphosphate solution on the foliage.
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