What are the reasons for poor coloration and low sweetness in muskmelons

Muskmelons grown in plastic greenhouses are about to hit the market in large quantities. Every buyer hopes to buy muskmelons that are good in color, sweet and crisp, and farmers who grow muskmelons especially hope that their muskmelons will be liked by buyers and fetch a good price. At present, some muskmelons sold on the market indeed have poor color and sweetness, and their selling price is 20-50% lower than that of high-quality muskmelons. What exactly causes muskmelons to have poor color and be not sweet? The main reasons are as follows:

1. Improper variety selection. The sweetness of muskmelon is related to its varietal characteristics, so high-quality varieties must be selected when planting muskmelons.

2. Excessive pruning, with too small a proportion of mature leaves, insufficient nutrient supply during the period from fruit ripening to sugar accumulation, early senescence of the plant, aging of leaves, and weakened or lost ability to manufacture nutrients. The fruit epidermis is thin and crisp; in order to maintain its own development and replace the leaves in manufacturing nutrients, by maturity the fruit rind. The amount of chlorophyll synthesized on the surface is greater than the amount decomposed, so the rind cells contain a large amount of chlorophyll and cannot turn yellow; therefore the color is poor and the sweetness is also poor.

3. Too few leaves are retained on the whole plant, the fruit is basically exposed outside, and most of the fruit surface receives direct light, which easily causes the fruit temperature to rise and inhibits the synthesis of yellow carotenoids. Direct light is favorable for the synthesis of green chlorophyll. Scattered light is favorable for the synthesis of yellow carotenoids; fruit in the shade, because it receives more scattered light, first shows the yellow of carotenoids. Therefore, fruit covered by leaves has good coloration.

4. Improper application of water and fertilizer. In the late fruit-setting stage of muskmelon, that is, 10 days before market, if there is no particularly severe drought, do not water; watering will significantly reduce the sweetness of muskmelon. During the growth period of muskmelon, special attention should be paid to increasing the application of potassium fertilizer, which has an obvious effect on improving muskmelon quality. Nitrogen fertilizer should be controlled; excessive application of nitrogen fertilizer will not only reduce the sweetness of muskmelon, but also cause excessive accumulation of nitrite, which is harmful to human health. For fertilizing muskmelon, the principles of controlling nitrogen, applying phosphorus, and increasing potassium should be grasped, and nitrogen, phosphorus, and potassium should be applied in combination. In order to increase the sweetness of muskmelon, 10 days before harvest, potassium dihydrogen phosphate or sweetness-enhancing agents such as Baofengling can be sprayed on the leaves, and a 10% concentration of white sugar can also be sprayed.