Top Ten Key Factors for Growing Watermelons

1. **Soil Selection**: Watermelons thrive in well-drained, loose, and fertile soils. Sandy loam or sandy soils with a pH value between 6.0 and 7.5 are ideal choices. When selecting soil, it is important to avoid soils with high heavy metal content, as this can negatively impact watermelon growth.

2. **Temperature Requirements**: Watermelons require high temperatures to grow well, with the ideal range being 25-30 degrees Celsius. Choose a location with ample sunlight and suitable temperature to ensure the watermelons receive sufficient sunlight.

3. **Water Supply**: Watermelons have high water requirements, especially during flowering and fruiting stages. Maintaining appropriate soil moisture is crucial for the growth and development of the fruit. Avoid overwatering to prevent waterlogging, which can affect the root system's respiration.

4. **Nutrient Supply**: Adequate nutrient supply, particularly nitrogen, phosphorus, and potassium, is essential during the growth period. Applying organic or chemical fertilizers before planting or regular fertilization during the growing period ensures healthy plant growth.

5. **Pest and Disease Control**: Watermelons are susceptible to pests like aphids and diseases like cucumber mosaic virus and powdery mildew. Appropriate control measures, such as regular pesticide spraying and optimizing planting density, can be adopted. Regular inspections to detect and address pest and disease issues timely can prevent the spread and impact on yield.

6. **Support Structures**: As a sprawling plant, watermelons require support structures to keep the fruits off the ground. Bamboo poles or wire mesh can be used to build supports, or pruning and adjusting can be done to organize the vines. This helps reduce disease exposure and promotes better air circulation and even sunlight distribution.

7. **Leaf Management**: Maintaining healthy plant growth by promptly removing yellowed or pest-damaged leaves can enhance yield and quality. Effective leaf management improves photosynthetic efficiency, nutrient absorption, and distribution, which boosts the fruit's sugar content and taste.

8. **Timely Harvesting**: Indicators of watermelon maturity include a dried stem and a sunken navel. Timely harvesting at this stage ensures good fruit quality and taste. Use clean tools to cut the stem to avoid fruit damage during harvesting.

9. **Planting Density**: The planting density, which impacts the number of plants per acre, plays a significant role in yield and quality. Typically, a planting density of 3,000-5,000 plants per acre is recommended, but it can be adjusted based on geographical conditions, varieties, and agricultural practices.

10. **Pest and Disease Monitoring**: Regular monitoring for pests and diseases within the watermelon fields helps in early detection and treatment, preventing widespread infestations and yield loss. Monitoring tools like yellow sticky traps or light traps can be employed. Effective and scientific pest control methods should be used to ensure product quality and safety.

Solutions for Watermelon Cultivation:

1. **Smart Irrigation System**: Utilizing IOT technology, establish smart agricultural greenhouses with integrated water and fertilizer machines and control systems. The water-fertilizer machine mixes appropriate fertilizers based on soil nutrient demands and growth patterns. The control system uses sensor data on soil moisture and temperature to automate and schedule irrigation, ensuring optimal water supply for crops.

2. **Water-Fertilizer Machine**: Known as a fertigation machine, it uses a pressure system to blend soluble solid or liquid fertilizers according to soil nutrient levels and crop needs. The mixture is supplied through a controlled pipeline system, delivering water and nutrients proportionately to the root zone. This keeps soil around the main root area loose and adequately moist while catering to the specific growth stages of different crops.

3. **Monitoring and Control Platform**: Via IOT platforms on mobile or PC, farmers can monitor greenhouse temperature, humidity, light, and other environmental metrics in real-time. Intelligent control based on these data allows for adjustments to create ideal growing conditions. The platform also offers historical data analysis, aiding better crop management practices.

4. **LED Display Screens**: Installing LED screens inside the greenhouse can display real-time environmental data, helping farmers understand parameter changes visually and make timely alterations. LED screens can also show images or videos of crop growth, aiding in better monitoring and management.

These solutions provide real-time, quantitative, and precise monitoring and control, helping farmers manage watermelon cultivation efficiently, enhance yield and quality, and reduce resource wastage. Additionally, they offer convenient mobile and PC management platforms, enabling farmers to monitor and manage watermelon cultivation anytime, anywhere, achieving smart agriculture.