Overview
Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus, commonly known as watermelon, is a vine-like flowering plant belonging to the Cucurbitaceae family. This tropical and subtropical plant is widely cultivated for its juicy and sweet fruit that is consumed as a refreshing snack all over the world.
Origin and Distribution
Watermelon is believed to have originated from southern Africa, particularly from the Kalahari Desert region. However, it has been widely cultivated since ancient times in various parts of the world, including Egypt, China, and India. Today, it is commercially grown in more than 100 countries across the globe, including the United States, Spain, Italy, and Turkey.
Common Names
Watermelon is known by different names in various languages and regions. In English-speaking countries, it is commonly referred to as watermelon, whereas in Spanish, it is called sandía, and in French, it is known as pastèque. In some African countries, it is known as karpuz and in Turkish, kavun.
Appearance
The watermelon plant is a sprawling vine with stems that can grow up to 3 meters long. The leaves are large, round, and deeply lobed, with a rough texture, and are covered in fine hairs. The flowers are yellow and grow on short stalks. The fruit of the watermelon is oval or round-shaped and can weigh anywhere from a few pounds to over 100 pounds. The flesh of the fruit is juicy and sweet, consisting of red or yellow pulp that contains numerous black or white seeds.
Uses
The primary use of watermelon is as a popular and refreshing fruit that is enjoyed raw or in fruit salads. The fruit is also used in the production of juices, smoothies, jams, and candies. The seeds of the watermelon can be roasted and eaten as a snack or added to salads. Apart from its culinary uses, watermelon is also believed to have numerous health benefits due to its high water content, vitamins, and antioxidants. In traditional medicine, watermelon has been used to treat various health conditions, including inflammation, high blood pressure, and heart disease. Additionally, the rind of the watermelon has practical applications, such as being used to make pickles or being fed to livestock as a source of nutrition.
Light Requirements
The plant Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus requires full sun exposure to thrive. It grows best in areas with abundant sunlight and relatively low shade. The plant needs at least 6-8 hours of direct sunlight every day. Insufficient light may lead to stunted growth, poor yield, and susceptibility to diseases.
Temperature Requirements
The plant Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus grows well in warm temperatures with a range of around 22°C to 35°C. The ideal temperature range for optimal plant growth is between 24°C and 32°C. Temperatures below 16°C or above 38°C can cause damage to the plant. The plant is highly sensitive to frost, and exposure to freezing temperatures can lead to death or significant yield loss.
Soil Requirements
For optimal growth, the plant Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus requires well-drained soils with excellent water-holding capacity. The ideal soil pH range is between 6.0 and 7.6, and the plant can tolerate mildly acidic to alkaline soils. The plant prefers sandy loam or loamy-sandy soils with good aeration and sufficient organic matter. Waterlogged or heavily compacted soils can inhibit root development, leading to poor growth and yield.
Cultivation of Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus
Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus, commonly known as watermelon, is a popular summer fruit with refreshing juicy flesh. Below is a guide on how to cultivate this crop.
Sowing and Watering Needs
The seeds of Citrullus lanatus are sown in early spring indoors. The seedlings are planted outside when all danger of frost is passed. These plants demand adequate water supply for optimal growth since they have deep root systems. Therefore, keep soil consistently moist but not waterlogged. Water supply also affects the fruit quality: too little water supply affects the taste and texture of the fruit, while too much water supply leads to bland-tasting fruit. Therefore, ensure you water the plant deeply when the topsoil is dry, and avoid soaking the foliage to help prevent disease.
Fertilization
Citrullus lanatus plants need additional fertilization beyond what is present in the soil. Apply a slow-release fertilizer rich in nitrogen as soon as you plant the seeds. Then, apply another nitrogen-rich fertilizer at the appearance of the first flowers. Finally, when the fruit is set, apply a fertilizer rich in phosphorous and potassium to encourage fruit maturation and improve its taste and sweetness. Always follow the manufacturer's instructions for application rate and timing.
Pruning
Watermelon plants require little pruning, but you can remove the lateral vines to encourage a more robust central leader. Furthermore, pinch off the first fruit to make sure the plant channels its energy towards vegetative growth. Once the plant has several female flowers, you can pick the male flowers to avoid cross-pollination and fruit with undesirable seeds or qualities.
Propagation of Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus
Citrullus lanatus (Thunb.) Matsumura & Nakai var. lanatus, commonly known as watermelon, can be propagated through both sexual and asexual methods. The plant is primarily propagated through seeds, but vegetative propagation methods such as cuttings and grafting are also used for commercial production.
Sexual Propagation
Watermelon seeds are planted in the soil after the danger of frost has passed and the soil temperature has warmed up to a minimum of 60°F (15.5°C). The seeds are sown directly into the ground or started indoors and transplanted outdoors after the danger of frost has passed. Seeds are usually planted 1 inch (2.5 cm) deep and 2 inches (5 cm) apart. The seeds germinate in 4-12 days depending on soil temperature and moisture.
Asexual Propagation
Asexual propagation techniques are used to maintain desirable characteristics such as disease resistance and fruit quality. Vegetative propagation is achieved through cuttings or grafting.
Watermelon cuttings are taken from healthy and disease-free plants. The cuttings should be taken from the main stem, 8-10 inches (20-25 cm) long with 2-3 leaves. The lower leaves are removed, and the cutting is planted in a moist soil mix. The cutting is placed in a warm and humid environment to root. The cutting should be kept moist and out of direct sunlight until roots have developed.
Grafting involves taking a scion from a desired cultivar and joining it to a rootstock from a different plant. The scion is chosen for its desirable fruit characteristics, while the rootstock is chosen for its disease resistance and vigor. The two plants are joined together, and the graft union is wrapped to hold the two plants together. The plants are kept in a warm and humid environment to promote graft union formation.
Disease Management
Citrullus lanatus can be affected by various diseases that can cause significant damages to the plant and reduce yield. Here are some common diseases that might affect the plant and ways to manage them:
Fusarium wilt
The disease is caused by the fungus Fusarium oxysporum, which affects the roots, causing wilting, yellowing of leaves, and death of the plant. Avoid planting in infected areas and ensure proper drainage to prevent waterlogging. Use resistant cultivars and apply fungicides such as benomyl or thiophanate-methyl as a preventive measure.
Gummy stem blight
The disease is caused by the fungus Didymella bryoniae, which attacks the leaves, stems, and fruits, causing lesions, cankers, and rot. It can be managed by using resistant cultivars, crop rotation, sanitation and pruning, and fungicide sprays with products such as azoxystrobin, pyraclostrobin, and copper-based fungicides.
Anthracnose
The disease is caused by the fungus Colletotrichum orbiculare, which causes circular sunken spots on leaves, stems, and fruits. It can be managed by pruning and removing infected parts, avoiding overhead irrigation, and using fungicides such as chlorothalonil or mancozeb.
Pest Management
Citrullus lanatus can be affected by various pests that can cause significant damages to the plant and reduce yield. Here are some common pests that might affect the plant and ways to manage them:
Aphids
Aphids suck sap from the plant, causing stunted growth, yellowing of leaves, and transmission of viral diseases. They can be managed by using natural enemies such as parasitic wasps and lady beetles, or insecticides such as neem oil and pyrethroids.
Cucumber beetles
Cucumber beetles feed on the leaves, stems, and fruits of the plant, causing wilting and transmission of bacterial diseases. They can be managed by using row covers, crop rotation, and insecticides such as pyrethroids or carbaryl.
Squash bugs
Squash bugs feed on the leaves, causing wilting and transmission of bacterial diseases. They can be managed by using row covers, handpicking and removing them manually, and using insecticides such as pyrethroids or carbaryl.
It is essential to monitor the plant regularly, practice crop rotation, maintain good field hygiene, and follow safe insecticide practices to effectively manage pests and diseases in Citrullus lanatus.
