Causes of bitterness in cucumber and its preventive measures

July 16, 2021

In recent years, with the gradual expansion of the cultivation area of ​​cucumbers in protected areas, many growers have reported that the cucumber root melons cultivated in protected areas in early spring have a bitter taste, which seriously affects the economic benefits of cucumbers in protected areas.

The bitterness of cucumbers occurs because cucumber plants contain a substance called bittersin C (C32H50O8), which is present not only in the plants but also in the fruits of cucumbers. The content of bitterness C in different parts of the same fruit is different. Generally, the bitterness of the fruit stem is relatively strong, while the top part of the fruit is bitter or has no bitterness. Cucumber varieties, growth conditions, plant nutritional status, vigor and strength, all affect the occurrence of cucumber bitterness. When there are many nitrogen, low temperature, lack of sunshine, malnutrition, and poor plant growth and disease, bittersone is easy to form and accumulate. Therefore, it is necessary to cultivate the vegetative and reproductive growth of cucumber, aboveground and underground. The balanced growth of the department is a fundamental measure to prevent the occurrence of bitter taste in cucumbers.

1. The heritability and prevention of bitterness of cucumber

The heritability of cucumber bitterness is controlled by the dominant single gene Bi, and the degree of bitterness is determined by the modified gene Mo. Bibi is not bitter; Mobi is slightly bitter; MoBi, Bibi, and BiBi are bitter in taste; cucumbers with bitter taste should not be left to grow. Judging from the current resources of cucumber varieties, there is absolutely no bitter cucumber variety. Therefore, in terms of cultivation, cucumber varieties with a slightly lighter bitterness should be selected.

2. The effect of cultivation measures on bitterness of cucumber and its prevention

a. Temperature When the temperature or ground temperature is lower than 13 °C, the cell permeability decreases, nutrients and water absorption is inhibited, cucumbers are susceptible to bitterness; when the greenhouse temperature is higher than 30 °C, and the duration is long, the leaf assimilation function weakens. Over consumption of photosynthetic products or malnutrition of cucumbers can also cause bitterness. Therefore, we should increase the temperature and heat preservation performance of the protection facilities as much as possible, adjust the temperature well, and avoid the temperature boundary formed by bitterness.

b. Cultivation and management of water cucumber should be based on the growth status and ecological characteristics of the plant, and timely supply the water needed for its birth, in order to maintain the turgor pressure of the plant tissue, the stability of the plant body temperature and the smooth progress of the biochemical reaction. Watering should be done a small number of times and the water temperature should not be too low. The hose micro-irrigation technology should be used as far as possible to prevent the decomposition of esterase indirectly due to the water deficit in the plant, in order to avoid the formation of cucumber bitter pigment C. And enter the fruit under dry conditions. Special attention should be paid to the fact that after planting, the seedlings should not be excessive, otherwise the root melons are easy to bitter.

c. Nutrition should prevent excessive application of nitrogen fertilizer or insufficient phosphorus and potassium fertilizers in production. In particular, excess nitrogen fertilizer can easily cause leggy plants; with the continuous growth of plants, the amount of nitrogen fertilizer should be increased, and fertilization should be balanced during the flowering period. Nitrogen, Phosphorus, potassium ratio of 5:2:6, while outside the roots should be combined fertilizer. 1 Foliar application of rare earth micro-fertilizers: spraying once at the seedling stage, initial flowering stage and young melon stage can increase the disease resistance of the plants and increase the sugar content by 1 to 2 percentage points. 2 Foliar spraying urea solution:

In the flowering and fruiting stages, spraying urea with 7.5 kg water and 2250 kg water per hectare can not only increase the yield of cucumber, but also improve the quality of cucumber, especially the sweetness and brittleness. 3 Spraying cytokinin on the leaf surface: spraying 2-3 times of new-type antibiotic Tongmai No. 1 before and after the flowering stage of cucumber, which can increase the yield of cucumber by more than 25%, increase the fruit setting rate by 30%, and increase the sugar content by 1-2%. , but also improve the quality of cucumber.

d. Density of dense colonization, poor light, decreased photosynthesis, and less accumulation of dry matter, will lead to increased bitterness of cucumber. At present, the cultivation density of cucumbers in protected areas is generally 5.55-63,000 plants/hm2, which inevitably has a small amount of seedlings in the early stages and is a waste of land. After the plants are full, they are shaded by each other, resulting in lack of light. In case of rainy days, A large number of melons have become aggravated by diseases, and the yield has not reached the peak and they have come back down. It is difficult to achieve a bumper harvest. For this reason, cucumber cultivation in protected areas should adopt the method of early close planting and late planting, ie common plant spacing 26-30cm, row spacing 60cm, planting by 15cm plant spacing, 3rd, 6th, 9th... planting on the same ridge. , When it grows to 12-14 pieces of real leaves, it will be sharpened quickly, it will quickly pick up the melons, and the main vines will be unplugged after harvesting; the second, fifth, and eighth... The shelves will be planted when the plants grow to 1.2-1.4m in height. When it is sharp, it will speed up the process of fruiting, and when the main vine is harvested it will be unplugged. In this way, the early yield is increased by nearly one time, and the remaining 14 or 7 strains will increase to 45 cm, which greatly improves the ventilation and light transmission conditions, improves the rate of cucumber production, yield and disease resistance, and also reduces bitter melons. happened.

e. Injuring the roots in the seedlings, shoveling the soil, and easily injuring the roots when the soil is too dry, and the bitterness of the cucumbers is aggravated. Seed application sowing on the production of sand table, rooting, rooting, plastic seedlings or paper pockets, cultivation should be used as much as possible mulching mulching, if not mulching, shoveling should be slightly earlier, late slightly Shallow, seedlings slightly shallower, farther away from the seedlings.

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