Standard Product Sizes for Watermelons (S~L Size)

The standard sizes for watermelons in Korea follow the specifications set by the National Agricultural Products Quality Management Service (NAQS). There is a preference for medium to large watermelons.
 

Characteristics of High-Quality Watermelons

High-quality watermelons are distinguished by their color, freshness, ripeness, and the absence of major and minor defects.

1. Color: The rind should have a vibrant, glossy color unique to watermelons. 2. Freshness: The stem should be fresh and not wilted, and the rind should be firm. 3. Ripeness: The flesh should have a distinct color characteristic of the variety and be appropriately mature. 4. Major Defect Fruit / Minor Defect Fruit: There should be no major or minor defects. In Korea, watermelons command the highest prices from April to May. In regions like Gochang, watermelons are shipped year-round. The farm surveyed for this study was a large-scale operation with over 10 greenhouses.

Cultivation Schedule for Watermelons in Korea by Growth Period
 

Watermelons can be grown throughout the year depending on the cultivation method, resulting in diverse growth schedules. In this case, farms using Nousbo's “Hi-Cote” Controlled Release Fertilizer (CRF) aimed for an early July harvest. Like most facilities utilizing cultivation under structure, where Electrical Conductivity (EC) levels often exceed 7, the use of Hi-Cote was notably different as the initial understock did not perish, deemed safe by the farm's representative.
 

▲(Left) Use of Hi-Cote Fertilizer, (Right) Use of Conventional Fertilizer
 

Even at a glance, locations using Hi-Cote Controlled Release Fertilizer (on the left) display more intense leaf density and richer leaf colors compared to those using conventional fertilizers (on the right). Conventional fertilizers have high Electrical Conductivity (EC), often leading to plant death even after transplanting and fertilization, especially during flowering and post-fertilization periods. In contrast, Hi-Cote Controlled Release Fertilizer withstands high salinity effectively during early growth stages.

Characteristics and Advantages of Hi-Cote Fertilizer

1. Characteristics of Hi-Cote CRF
 

A. Improved Early Growth: Contains more than 20% nitrate nitrogen, promoting rapid early growth and ensuring safety from nutrient deficiencies. For watermelons, vigorous fertilizer efficiency is crucial in the early growth stages to secure the number of stems and support development. Additionally, with the recent understock's strong nutrient absorption ability, it is beneficial for the fertilizer to have a rapid initial effect and a somewhat slower release during the female flowering and fruit set periods.

B. Maximized Fertilizer Use Efficiency: Applying the fertilizer directly to the crop's rhizosphere maximizes fertilizer use efficiency. By targeting the understock's rhizosphere, the efficiency of fertilizer utilization is significantly enhanced.

C. 100% Coated Controlled Release Fertilizer: All components (nitrogen, phosphate, potassium) are coated using unique advanced coating technology. This ensures stability against fertilizer damage and nutrient loss.

D. Designed to Meet Crop Nutrient Requirements: The fertilizer is formulated with Linear and Sigmoid release technologies to match the crop's growth period and nutrient needs. This design promotes fruit thickening growth and maximizes the leaf area index (LAI) throughout the development of the watermelon.

2. Advantages of Hi-Cote CRF

A. Reduced Fertilization Labor: By applying fertilizer only once at planting, nutrients are supplied throughout the entire growth period, eliminating the need for additional fertilization. This reduces the frequency of injected fertilization and thereby decreases additional labor requirements.

B. Reduced Fertilizer Usage: Fertilizer is applied directly to the crop's root zone, minimizing application to areas like interrow and hill spacings where crops are not planted. This reduces overall fertilizer usage, as plants absorb the Hi-Cote fertilizer in the root zone and any fertilizer accumulated in the interrow and hill spacings.

C. Maximized Fertilizer Utilization: Nutrients are released when needed by the crop, reducing losses due to volatilization and eluviation. Continuous fertilizer efficiency prevents deficiencies during fruit maturation, promoting watermelon growth and quality.

D. Alleviation of Salinity in Controlled Environments: Reduced fertilizer usage decreases salinity issues in greenhouse cultivation. Slow nutrient release allows for effective EC absorption, mitigating salinity problems.

E. Minimized Environmental Impact: Reduced fertilizer usage significantly lowers greenhouse gas emissions and reduces water pollution from non-point sources, thereby improving water quality.

Recently, watermelon cultivation in Korea has expanded significantly, with over 80% being grown in controlled environments. The trend is to produce 2-3 fruits per plant. Under traditional cultivation methods, watermelons weighed around 8-10 kg. However, with the use of Nousbo's Hi-Cote, the weight has increased to 12-14 kg, and the brix (sweetness) has also improved.

A test watermelon was cut open, revealing high sweetness and a potential weight of over 13 kg, likely qualifying for the highest grade. The farm representative plans to use Hi-Cote on over 10 hectares in the future. Farmers have also tried other companies' controlled release fertilizers but are satisfied with the cost-effectiveness of the Nousbo’s CRF.