Causes of premature senescence in the late stage of watermelon cultivation with plastic film mulching

First, nutrient depletion. Watermelons are generally given a fairly generous base fertilizer, and with plastic film mulching, the soil temperature is high, the fertilizer breaks down quickly, and the plants absorb a great deal of it, so after fruit set they show signs of nutrient depletion, leading to premature senescence in the late stage.
Second, leaving the first fruit on the vine. Early-maturing watermelons generally produce their first female flower at the 7th to 8th node on the main vine, just when the vine is beginning its vigorous growth. If the first fruit is kept, it will consume a large amount of nutrients, affecting the growth and development of the vine, very easily producing a “small old vine”, causing premature senescence and resulting in small fruits.
Third, loss of moisture. During the fruiting stage, watermelons face high temperatures, and under plastic film mulching the root system is shallow, the soil easily loses moisture, and when the water content is too low, premature senescence results.