Climate and Soil
It is a warm season crop mainly grown in tropical and subtropicalregions. Generally, a long period of warm, preferebly dry weatherwith abundant sunshine is required. It is susceptible to frost. Excesshumidity will promote the attack of diseases and insect-pests. Forgood quality and sweetness, dry weather during the fruit developmentis necessary. It requires tropical climate and fairly high temperature(35-40'C) during fruit development. Cool nights and warm days areideal for accumulation of sugars in the fruits. Maturity is hastened ifnights are warm. The average temperature for growth should be around30-35C with maximum around 40'C and minimum between 20 and25'C. The optimum moisture and temperature range of 18-25'C isrequired for germination.A well drained loamy soil is preferred. Light soils that warm quicklyin spring are usually used for early maturity. In heavier soils, vinegrowth is high and fruits mature late. The long tap root system ofwatermelon has been adopted in riverbeds. The soil in which it isgrown should not crack in summer and water log in rainy season.It prefers a soil pH of 6.0-7.0. It is slightly more tolerant to mediumsalt concentrations.
Sugar Baby (Before 1962) : This variety produces small tomedium sized fruits with dark green skin. The flesh of the fruit isdeep red and very sweet having 9-10 per cent TSS. It yields 72 q/acre.
Sowing Time :
(i) Mid January to March (ii) November to December (Under protection)Seed Rate : Use 1.5 Kg seed for small seeded varieties and2.0 kg seed for large seeded varieties per acre.
Prepare 2.5-3.0 metre wide beds. Seeds should besown on both sides of the beds at a distance of 60 cm between theplants.
Manures and Fertilizers
Apply 8-10 tonnes of farmyard manure along with 25 kg of N (55kg. of Urea) 16 kg. of P205 (100 kg of Single Superphosphate) and 15kg. of K20 (25 kg of Muriate of Potash) per acre in the same way asin the case of muskmelon.
During initial stages of growth irrigate weekly. Later the irrigation should be given at 9-13 days interval. Towards maturity irrigation should be given at longer interval. Total number of irrigations would be 7 to 9.
The crop would be ready for harvest in 95-120 days after seedsowing depending upon the cultivar. The fruits should be harvestedwhen fully developed and mature. Signs of maturity are drying oftendrils, change in colour of ground spots to yellow and thumping ofmatured fruits give dull sound.
Land should be free from volunteer plants of the same crop orother crossable species. A seed crop field must be isolated fromother varieties all around to a minimum distance of 1000 metre and500 metre for foundation and certified seed, respectively. Systematicand timely field inspections at different stages of plant growth areessential to ensure the production of genetically pure seed. Aminimum of three field inspections viz., before flowering, duringflowering and fruiting and finally at fruit maturity are required. Theedible fruit should be examined for internal fruit characters andsweetness.Watermelon fruit is ready for seed harvest at its edible stage ofmaturity. Harvesting can be delayed for a few days after the fruitreaches edible stage. Dryness of the tendrils at the point ofattachment of fruit to the vine and change of belly colour from greento yellow are the other important criteria for judging the fruit maturity.The seeds may be harvested from the over-ripe fruits but in order tocorrectly inspect the interior fruit quality, it should be harvested atthe time of its edible stage. The seeds are removed from the flesh,washed with water and dried in shade before packing.