Water and fertilizer management is an important part in the whole growth cycle of small watermelon. The irrigation frequency of different growth stages should be adjusted according to the needs of each stage, the irrigation EC value should also be adjusted with the timely adjustment, the PH value is basically maintained 5.5-6.5, and the weak acid environment can ensure the balanced absorption and absorption efficiency of each nutrient element.

In the early stage of planting, slow seedling is the main method, adequate irrigation is maintained, EC is controlled between 1.5-1.8ms /cm, and the amount of liquid return is controlled at about 50%。

After slow seedling to the first female flower, to control the length of the main, irrigation EC control at 1.8-2.0 ms/cm, the amount of liquid return control at 10%-20%.

After the first female flower opens, this stage is an important stage to regulate the transformation of plant vegetative growth into reproductive growth, and the irrigation EC is gradually increased to 2.5ms/cm, and the adjusted liquid return volume is maintained at about 10%.

After fruit set, the fruit is rapidly expanded, the demand for water and fertilizer is relatively large, the irrigation EC is controlled at 2.2-2.5 ms/cm, and the liquid return is maintained at 15%-25%.

At the later stage of fruit setting, in order to increase the sugar content of the fruit, the irrigation EC was controlled at 2.5-3.0ms /cm, and the liquid return was adjusted to about 5%.

The reference index for the implementation of automatic irrigation program is the cumulative radiation amount of light. Generally, 100J/cm2 is accumulated to start a single irrigation, and the single irrigation amount is controlled within 75ml-100ml according to the different ratio of matrix. When the irrigation strategy needs to be adjusted according to the proportion of liquid return, the irrigation quantity of a single irrigation is generally kept unchanged, and the cumulative radiation quantity of a single irrigation is adjusted to achieve the purpose of adjusting the irrigation quantity. The irrigation procedure starts 2h after sunrise (1 to 2 hours in rainy days) and ends 2h before sunset (1 to 2 hours in rainy days).

The temperature requirement of small watermelon is relatively high, the temperature range suitable for watermelon growth is 16℃ -30℃, the night temperature is controlled at about 18℃, and the daytime temperature is controlled at 25℃ -28℃.

The relative humidity of the air during the growth of small watermelon should be controlled between 70% and 90%. The relative humidity of the air at night is generally controlled between 85% and 90%. Too much humidity is easy to breed diseases, and a certain amount of ventilation can be properly maintained.

The growth of small watermelon has a relatively high demand for light, taking the plants after sitting melon as an example, the amount of light radiation to maintain its normal growth is about 1000J/cm2.

A large amount of CO2 is needed for plant photosynthesis during the day.