Watermelon (Citrullus lanatus), is an important cucurbitaceous crop, grown in warm, tropical or subtropical climates. It is a popular fruit, especially during summer, known for its sweet and refreshing taste. The fruit is highly nutritious, rich in 92% water, 7% carbohydrates, 0.2% protein and 0.3% minerals. Uttar Pradesh, Andhra Pradesh, Tamil Nadu, Karnataka and Orissa are the major watermelon producing states in India. As per the Second Advance Estimate for 2021 – 2022, the total area under watermelon cultivation is estimated to around 1.23 lakh ha while total production is estimated to be about 3.46 million tonnes in India. Following improved agricultural practices can ensure successful watermelon harvest with increased quality and yield of fruits.   Watermelon Crop at a Glance Botanical Name: Citrullus lanatus Common Name: Tarbooz (Hindi), Tarbuza (Punjabi), Kalangadi (Kannada), Tarabuja (Odia), Pucchakaya (Telugu). Crop type: Fruit crop Soil and Climate  A well-drained sandy loam soil with a pH of 6.0 – 7.0 is highly preferred for watermelon cultivation. Soil should be fertile and rich in organic matter. Lighter soils which warm up quickly are usually preferred for early yield while heavier soils have high vine growth but delays fruit maturity. The soil should neither crack during summer season nor waterlog during rainy season.   Watermelon is a warm season crop and is highly susceptible to frost. It requires a longer period of warmth, preferably dry weather with abundant sunshine. 18 – 25°C of sowing temperature with optimum moisture is required for germination. An average temperature of 30 – 35°C is required for growth while temperature range of about 35 – 40°C during fruit development is ideal for good quality and sweet fruit. Cool nights and warm days can increase sugar accumulation in fruits.   Varieties/Hybrids  Hybrid  Features  NS 295 watermelon  Type: Oval to oblong  Days to maturity: 80 – 85 days  Jubilee-light green with light green stripes is the rind pattern  Oblong shaped fruit, deep crimson flesh colour  Sweetness TSS: 11-12%  Fruit size: 9-12 kg  AFA 306 watermelon  It is a vigorous and strong vine hybrid  Fruits: oval round dark green with dark stripe  Fruit weight: 10 –12 kgs  Deep red flesh, very sweet & crispy  Fruit maturity: 85 -90 days after sowing  Excellent shipping quality and long shelf life  Tolerant to anthracnose, downy mildew diseases  Anmol yellow watermelon  The fruit is tall globe-shaped with dark skin and vague stripes, crisp and fine quality flesh  Fruit weight: 3-5 kg  Strong tolerance against diseases.  Harvesting: 75-80 days after sowing  Apoorva watermelon  Plant is strong with good vigour  Outer rind colour is light green with dark green stripe  Flesh colour is dark red with granular texture  Fruit weight: 8 -10 kg  Fruit is oblong in shape  Has good sweetness  Maturity: 90 to 100 days  URJA US-888 watermelon F1 Hybrid seeds  Early medium maturity fruit  Round sugar baby type hybrid  Fruit flesh is red with soft texture  Resistant to fusarium disease  Average fruit weight: 8 – 10kg  IRIS hybrid fruit seeds watermelon  Oblong fruit shape  Fruit has glossy black skin  Fruit weight: 10 – 12 kg  Fruit maturity: 70 – 75 days after transplanting  Sugar content: 11 to 12 brix  It is suitable for long transportation  Arun 0035 watermelon  Maturity: 38-40 days of flowering  Fruit shape is oblong  Fruit has black exterior colour  Fruit weight: 3-4 kg  They are high yielding, extremely good for transportation  Pakeeza watermelon  Fruit shape: Jubilee elongated oval  Maturity: 70-75 days  Deep red, granular flesh texture  Fruit weight: 8-10 kg  12% TSS sweetness  High yield variety of fruit  PAN 2053 Spl hybrid watermelon seeds  Maturity: 55-60 days after sowing  Fruit weight: 2.0-2.5 kg  Fruit shape is oblong  Fruit colour is blackish green  Excellent sweetness, crispy & suitable for distant transportation.    Season  Watermelon seeds are mainly sown during mid-December to January.  Seed rate  Varieties:  1 – 1.5 kg/acre for small-seeded types; 2 kg/acre for large seeded types  Hybrid: 300 – 400 gm/acre  Seed treatment  It is preferred to use pre-sprouted seeds to improve crop stand in the field. The seeds should be soaked in water overnight and should then be kept in gunny bag near a warm place. The seeds will start to germinate in about 3 to 4 days.  Treat the seeds with Trichoderma viride  at 20 gm/kg seeds or mix 5-10 ml of Pseudomonas fluorescens in 50 ml water and apply it for 1 kg seeds. It can also be treated with Metalaxyl 4% + Mancozeb 64% WP at 1 – 1.5 gm/lit water/kg seeds.  For seedling treatment, dip the roots of seedlings in Humetsu humic acid at 4 – 5 ml/lit water or Pseudomonas fluorescens at 5 ml/lit of water.   Land Preparation  Prepare the land to a fine tilth by ploughing.   Sowing Depth  Sow seeds at 2 – 3 cm depth.  Sowing methods  Watermelon can be direct-seeded or transplanted from nursery.  1. Direct-seeded method:  Methods of sowing  Furrow method  Pit method  Hill method  Furrows are to be made 2 – 3 m apart. Sow the seeds on either side of the furrows. Dibble 2-3 seeds at each place and remove the weak seedlings after germination and keep plant to plant distance as 0.75 – 1 m along the furrows. The furrow size should be of 60 cm.   Construct pits of 60 cm diameter and 60 cm depth. Maintain pit to pit distance of about 2 – 3 m.  Then fill the pits with well decomposed FYM and soil. Sow 4 seeds per pit. Later, remove unhealthy plants and retain only 2 or 3 plants pet pit.   It is usually adopted in riverbed cultivation. Construct a pit of 30 x 30 x 30 cm at a distance of 1 – 1.5 m. Fill the pits with equal proportion of soil and FYM. Pile the soil in the form of a hill and then sow 2 seeds per hill.   Furrow method Pit method Hill method Gap filling and Thinning  The seeds will germinate after 8 – 10 days of sowing. At that time, thinning is done by retaining 2 or 3 healthy seedings while removing the rest. Removed seedlings may be used for gap filling.  2. Transplanting method:  Nursery establishment  Polybag nursery  Portrays nursery  Use polybags of 200-gauge, 0.1 m of diameter and 15 cm height. Fill the bags with 1:1:1 ratio of red soil, sand and FYM mixture.  Portrays having 98 cells can be used. Sow 1 – 2 seeds per cell.     Field preparation for transplanting seedlings: Prepare raised beds of 1.2 m width and 30 cm height for sowing. In the case of drip system, place the lateral tubes in the center of each bed. Irrigate the beds through drip system for 8-12 hrs.   Transplanting: Transplant 12 days old seedlings in the main field. Then, plant the seedlings in the holes made on the beds at a distance of 60 cm distance.   Fertilizer Requirement  The general dose of fertilizer recommendation for watermelon is 40:20:30 kg/acre.  Nutrient  Fertilizer  Dosage  Stage of application  Organic  FYM  8 tons/acre  Mixed with soil during ploughing  Neem cake  40 kg  Mixed with soil during ploughing  Humetsu Humic acid  Drenching: 4 – 5 ml/lit water or  Foliar: 2 – 2.5 ml/lit water  Soil drenching: Can be done after irrigation   (or)  Foliar spray: Can be done 2-3 times at critical growth stages like root formation, branching stage & flower initiation to early fruit setting stage.  N  Urea  Basal – 43 kg  Top dressing – 43 kg  Basal application: Given before or at the time of planting.  Top dressing: Applied 30 – 35 days after sowing.  P  Single Super Phosphate (SSP)  125 kg  Basal  K  Muriate of Potash (MOP)  50 kg  Basal  Ca & B  Multiplex Chamak Micronutrient  Foliar: 3 gm/lit water    Start spraying with flower initiation with 2 or 3 sprays at spray interval of 20-25 days  Mg  Multiplex Moti Mg  Foliar: 0.5 gm/lit water  1st spray: 1 month after sowing or transplanting  2nd spray: 15 days after first spray  Micronutrients + Seaweed extract  Tapas Pushti All Plant Nutrient Mix  Foliar: 0.25 gm/lit water  1st spray: After 2 leaf stage  2nd spray: 15 – 20 days after first spray  (NOTE: The fertilizer should be applied in the form of a ring at 6 – 7 cm at the base of the stem)  Fertigation of nutrients can also be provided through drip system to supplement the required nutrients.   Fertigation Schedule  Crop Stage  DAT  Water soluble fertilizers per acre   Crop establishment stage  5 – 10 days  12:61:00 at 5 gm/lit water + V-Hume 5 ml/lit water  Vegetative stage    12 – 17 days  12:61:00 at 5 gm/lit water + Nutribuild  at 2.5 – 7.5 gm/lit water  19 – 24 days  00:52:34 at 5 gm/lit water + Allbor Boron at 1 gm/lit water  Flowering stage  26 – 32 days  13 :00 :45 at 5 gm/lit water + Gibrax Phytozyme at 1 – 1.5 ml/lit water  33 – 39 days  00:52:34 at 5 gm/lit water +  Magnesium Sulphate at 3 – 4 gm/lit   Fruiting stage  40 – 46 days  13 :00 :45 at 5 gm/lit water   47 – 53 days  Calcium Nitrate at 5 gm/lit water  54 – 60 days  Sulphur Liquid 2.5 ml/lit water  Harvesting  61 – 67 days  00:52:34 at 5 gm/lit water + Allbor Boron at 1 gm/lit  68 – 74 days  Calcium Nitrate at 5 gm/lit water + Multimax nutrient at 10 – 15 gm/lit water  75 – 80 days  13 :00 :45 at 5 gm/lit water + Gibrax Phytozyme at 1 – 1.5 ml/lit water  82 – 87 days  00 : 00: 50 at 5 gm/lit water + Ammonium Sulphate 3 kg    Irrigation  Watermelon crops have a deep tap root system, and it requires less frequent irrigation. 1st irrigation to direct sown watermelon crop can be delayed if the field has sufficient moisture. However, inadequate irrigation can result in poor germination and uneven growth. 1st irrigation for transplanted seedling is to be given immediately after transplanting and subsequent irrigation can be given at 10 – 14 days intervals.  In stage of crop growth, irrigate the crop at weekly intervals. Avoid over flooding the field. Avoid water stress especially during pre-flowering, flowering and fruiting stages. Restrict the irrigation only to the root zone areas and avoid wetting veins or vegetative parts, flowers and fruits. Stop irrigation at fruit maturity or 3 – 6 days before harvesting to maintain better sweetness and flavour of fruits. A total of 7 – 9 irrigations can be given in the entire crop duration. ‘Drip irrigation’ is highly recommended for better quality of fruit, minimizing disease and weed infestation and for water conservation.   Pollination  Pollination is a very important step in cultivation, contributing to fruit development. Both male and flowers grow on the same plant but separately in watermelon plant.   Honeybees: They are the primary pollinators. Insufficient pollination results in misshapen fruits. To encourage bee activity, 1 or 2 beehives can be placed per acre. Spraying chemicals in morning hours during flowering stage should be avoided.   Manual pollination: Hand pollination can also be done in the early morning. The stamen from the male flower should be brushed against the stigma of the female flower.  Mulching  Mulching can be done underneath fruit using straw or dry leaves. Now-a-days farmers are also using plastic sheets for mulching. It helps in moisture conservation, weed suppression and prevents fruits from being in contact with soil so as to reduce pest and disease attacks. As the crop is mainly cultivated during the period of high temperature and hot winds, mulching is necessary for watermelon cultivation.    Pinching/Training  Pruning improves yield and quality of fruits. When vines are about 1 m, apical shoots can be removed/pinched to promote growth of side shoots. During the initial stages of fruit setting, remove the malformed, damaged or diseased fruits. Only a maximum of 4 – 5 fruits can be retained per vine which can improve fruit size and yield.   Earthing up and Weed Management  Earthing up can be done after top dressing with nitrogen fertilizer. Keep the field free from weeds during the early stages of crop growth. Follow hand weeding at an interval of 15, 30 and 45 days after sowing.   Use of Growth Regulators  PGR  Technical content  Dosage  Benefits  Stage of Application  Ethrel Growth Promoter  Ethephon 39% SL   1–2.5 ml/lit water  Improve coloration and accelerates uniform ripening of fruits  2 – 3 weeks after full bloom stage  Katyayani Alpha Naphthyl Acetic Acid  Alpha Naphthyl Acetic Acid 4.5% SL     0.2 ml/lit water  Induces flowering, prevents shedding of flower buds, helps in   enlarging fruit size, increasing and improving the quality and yield of fruits  1st spray: During flowering  2nd spray: 20 – 30 days after first spray  Hoshi Sumitomo  Gibberellic Acid 0.001% L   1.25 ml/lit water  Increases plant size, stimulates flowers, enlarges fruit, and boosts crop yields  1st spray: 15 DAT  2nd spray: 15 – 30 days after 1st spray (30 DAT)   3rd spray: 45 DAT    Crop Protection Practices  Pests  Major pests of watermelon crops include red pumpkin beetle, fruit fly, thrips, aphids, whitefly, leaf eating caterpillar, serpentine leaf miner, red spider mite, cutworms and cucumber beetle.  To get a complete guide on pests viz., stage of occurrence, identification symptoms and its management turn to this insightful article – 10 Common pests of watermelon you need to know about and how to control them  Diseases  Major Diseases that affect watermelon crops includes;  Disease type  Diseases  Stage of occurrence  Fungal Diseases  Downy mildew  Vegetative stage  Powdery mildew  Vegetative, fruiting stage  Anthracnose  Vegetative, fruiting stage  Alternaria leaf spot  Vegetative stage  Fusarium wilt  Vegetative, fruiting stage  Gummy stem blight  Vegetative, fruiting stage  Bacterial Diseases  Bacterial wilt  Vegetative stage  Bacterial Fruit Blotch  Vegetative, fruiting stage  Viral Diseases  Bud necrosis disease  Vegetative stage  Cucumber mosaic virus  Vegetative, fruiting stage    To know about the disease causes, symptoms and management strategies look into this article – An Ultimate Guide to Watermelon Diseases: Causes, Symptoms, and Control Measures  Harvesting Indices  Generally, watermelon will be ready for harvest 30 – 40 days after flowering.   When the tendril near the stem gets dried, it indicates fruit maturity  On thumping/tapping, if the fruit produces dull hollow sound, then the fruits are ready for harvest  Fruit maturity is indicated when the fruit surface touching the ground shows a light yellow colour.  The rind of the fruit becomes hard and cannot be punctured with thumbnails on maturity.  Grading  Watermelons are graded depending upon their size, appearance, symmetry and uniformity in appearance. The fruit’s surface should be bright and waxy in appearance, devoid of scars, sunburn and abrasions.   Criteria for Range in Watermelon:   Tradable Parameters  Range I  Range II  Range III  Quality  Superior  Very good   Good  Colour, shape and size (With respect to characteristic true to variety)  Uniform  Semi-uniform  Reasonably uniform  Defects allowed (Paler part of any fruit region including bruises)  Nil  A slight defect in coloring for the paler part of the fruit which is in contact with the ground during growth period  Any defect in coloring in rind, slight abrasions/bruising, presence of cracks  Weight (kgs)  Above 5 – 10  2 to 5  Below 2  Range tolerance  5% of fruits falling in range II category  10% of fruits falling in range III category  15% of fruits with minimum standards  TSS (Optional)  Not less than 10°brix    Storage of Watermelon  Watermelon can be stored for about 15 days at 15°C. Lower temperature may cause chilling injury. It does not stand long transportation. During transportation in trucks, stack the fruits on dried grass to avoid damage and bruising.  It is important to not store or transport watermelons with apples, tomato, muskmelon and bananas because the ethylene produced from these fruits hastens softening and development of off-flavours to watermelon fruits. There is a high chance of losing crispiness and colour due to long period of storage.