The melons that are just sitting on the guainau and the melons that are under development grow stagnant. They gradually turn yellow, dry, and finally dry off from melon tip to whole melon. Pectin is a common problem in the production of melon vegetables, which directly affects the output and output value. In particular, greenhouse cultivation, if not properly managed, can be as high as 30% to 60%. There are many reasons for the production of melons, in general because the melons did not get enough nutrients in the growth process to stop development. The specific reasons are as follows:
First, the temperature is not suitable
Daytime temperatures are too high (35°C) or too low (below 20°C). The daytime temperature in the shed is higher than 32°C, and the nighttime temperature is lower than 18°C, which can cause photosynthesis to be blocked, decrease in assimilation products, increase in respiratory consumption, and accumulation of nutrients, leading to malnutrition and melding.
Melon vegetables suffer from low temperatures during the growth period, especially when the ground temperature is too low, which results in poor root development and reduced absorption capacity. This results in insufficient supply of nutrients and melons.
Second, low carbon dioxide concentration
Melon vegetables are generally sensitive to changes in carbon dioxide gas concentration. If the carbon dioxide concentration in the shed is too low, it can be easily digested.
Third, the cultivation density is too large, and the supply of fertilizer and water is unreasonable
The planting density is too large, even the shades are olivine, and the ventilation is poor, resulting in closed canopy, unfair shape, unfavorable to photosynthesis, less assimilation products, and easy to cause melons. Lack of water or lack of fertilizer due to improper fertilization caused by the lack of trace elements, but also affect photosynthesis.
IV. Unisexuality
There is a large temperature difference between day and night in nursery and early fertility in sunlight greenhouses. There are many female flowers and less male flowers. At this time, insects have not been pollinated without pollinators, and artificial pollination is not carried out. The results are mainly parthenocarpy and unisexual and weak varieties are easy to melon.
V. Overgrowth of stems and leaves
Due to more nitrogen and water, high night temperature, watering fertilizer before sitting on roots, temporary empty crops, and no water supply, the water supply and fertilizer are sufficient as usual, so that the stems are thick and long, the leaves are thin, and the growth is excessive. While the melon strip grows slowly, female flowers and young melons do not get assimilation products.
Six, fruit and fruit growth
There are too many female flowers and young larvae on the plant. Limited assimilation products can only be distributed to large or part of female flowers and young larvae, which will cause most of the female flowers and young larvae to disappear. Plant growth and fruiting period, if the following melon is not harvested in time, it is easy to cause the upper melon out.
VII. Serious damage to pests
Downy mildew, bacterial angular spot disease, anthrax, powdery mildew, scab, etc., all directly damage the leaves and cause leaf necrosis. In severe cases, the whole leaves or entire leaves are dried up, and photosynthetic and melons cannot be used. Insects such as aphids, tea aphids, and whitefly have absorbed malnutrition and metabolize melons by sucking leaf juice and leaf contamination of melons and vegetables, destroying photosynthesis.
Eight, phytotoxicity
Unreasonable choice of pharmaceutical agents, high spraying concentration or excessive spraying of pesticides, so that the melons of vegetables suffer from phytotoxicity and aging and dry, decreased or even lost the photosynthetic ability of the leaves. In addition, mechanical damage during management may also cause damage to young melons.
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