How to improve the quality of watermelons in greenhouse?

(agricultural getting Rich Network) with the adjustment of industrial structure, the cultivation area of watermelon in greenhouse is getting larger and larger. But the accompanying problem is that the taste of watermelons in the greenhouse is getting worse. How to improve the quality of watermelons in greenhouse? Mainly pay attention to the following aspects:

The sweetness of watermelon to improve the intensity of photosynthesis is mainly determined by the amount of sucrose, fructose, glucose and other sugars, and the formation of these sugars can not be separated from photosynthesis. Therefore, the following measures can be taken to improve photosynthesis intensity. Improve the light intensity: select the drip-free greenhouse film which is resistant to low temperature and anti-aging, keep the greenhouse film clean, wipe the film once every 7 days, remove the dust from the film and enhance the light transmittance. Prolong the lighting time: it can be realized by artificial light supplement.

Increase carbon dioxide content of ventilation: after 9: 00 a. M. on a sunny day, open the vents for ventilation. When the temperature is low, the vent should be small. Increased application of carbon dioxide: horse dung can release carbon dioxide during fermentation and can accumulate fresh horse manure in the shed, with 5 kilograms per cubic meter; burning propane produces carbon dioxide, burning 1.2 to 1.5 kilograms of propane in a greenhouse of 600 square meters, which can increase the concentration of carbon dioxide in the greenhouse to 0.13%. Using coke carbon dioxide generator, carbon dioxide can be released when coke is fully burned. Put concentrated hydrochloric acid in a corrosion-resistant container and then add a small amount of lime (calcium carbonate) to produce carbon dioxide through chemical reactions; dry ice is released directly in the shed. Carbon dioxide application period is mainly in the watermelon growth period, especially in the fruit development period, the appropriate time for application is around 10:00, the concentration is 0.1% 0.5%.

Reduce nitrogen supply after watermelon expansion, we should reduce nitrogen supply and appropriately increase the amount of potash fertilizer. In the topdressing of expanded melon fertilizer, 15 grams of potassium sulfate was applied per plant, especially to control the absorption of nitrogen in the later stage of watermelon growth, which would reduce the quality of watermelon if too much nitrogen was absorbed. Because the watermelon no longer grows at this time, the excess nitrogen accumulates in the melon, which makes the sweetness and flavor of the watermelon worse. The increase of lateral vines during this period is a sign of excessive nitrogen.

Increasing the temperature difference between day and night and higher temperature in daytime can increase the intensity of photosynthesis. lowering the temperature in the greenhouse after sunset can reduce the intensity of plant respiration, reduce the consumption of sugar, and store more sugar in melons, which is beneficial to the accumulation of sugars and improve the sweetness of watermelons. Strengthening ventilation at night in the later stage of watermelon growth can artificially increase the temperature difference between day and night in the greenhouse.

Before harvest, the watered fruit began to develop to 2-3 days before harvest, and environmental conditions and cultivation measures played a decisive role in the quality of watermelon. Many watermelon producing areas have the saying that "drought melons are sweet". The day before harvest, there was no rain, and watermelons were indeed sweeter, while watermelons tasted light or not when they encountered heavy rain before harvest. Therefore, watering should be stopped 5 days before watermelon harvest, which can relatively improve the sweetness of watermelon.