In early spring, the summer squash is cultivated, and it is easy to appear that the fruit enlargement stops halfway, yellowing, and wilting. In the end, it is dry, and this symptom may appear before and after flowering. It is commonly called melon. The following are the main points that cause melons to grow:
(1) In early spring cultivation, the leaf assimilation function declines, the photosynthetic accumulation of the plants is small, the flower buds are differentiated or the pollination is poor, and the auxin cannot be generated in the ovary, thereby causing the pumpkins to be transformed into melons.
(2) Since squash are cross-pollinated vegetables, pollen development is poor under low temperature and high humidity, and pollen is not easily distributed. Female flowers cannot receive fertilized pollen and cause melon. When the greenhouse temperature exceeds 35°C during the daytime and it rises above 20°C during the night, it will lead to plant growth, resulting in strong nutrient growth and poor reproductive growth. Therefore, when farmers usually manage, the daylight temperature in the shed should be controlled at 20-23°C, and the temperature should be controlled at 13-15°C at night to prevent the temperature in the shed from being too high.
(3) Cultivation of greenhouses in early spring is affected by short-day low-temperature sunlight, which causes squash to open more female flowers and less male flowers, resulting in poor pollination and melon production. Plants have poor ventilation and light transmission, especially after pollination of fruits. If there is insufficient light, the lack of nutrients produced by the leaves will easily lead to the growth of pumpkins. Some varieties of pollen undergrowth at low temperatures can also cause melons.
Control methods: First of all, to cultivate robust plants and promote the growth and development of plants; Second, to control the night temperature, to prevent the night temperature is too high, in order to reduce respiratory consumption; At the same time, before the application of carbon dioxide gas ventilation, promote assimilation; Is the use of artificial pollination or hormone treatment. Artificial pollination should be carried out before 9:00 a.m. on sunny days. The male flowers that are in full bloom in the day should be taken off and the petals removed. The entire stamens should be placed directly on the stigma of the male flowers for artificial pollination. Or use 20-40 mg/L of 2,4-d to coat the fruit shank and 80-150 mg/L gibberellin for fruit spray, which also has a good effect of flower protection and fruit protection.
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