1.1 BACKGROUND TO THE STUDY
Watermelon (Citrullus lanatus) is a tropical fruit and a flowing plant that belongs to the family Cucurbitaceae. It is an annual vine that has a prostrate or climbing habit and it originated in the deserts of Kalahari in South Africa. Watermelon is referred to as a pepo by botanists, a berry that has a thick rind (exocarp) and flesh mesocarp and endocarp. The flesh comprises about 65% of the whole fruit and contains over 90% water. Watermelons are cultivated commercially for their refreshing, sweet fruits which are mostly consumed as fresh fruit alone or as part of fruit salads or other desserts, in some African cuisines the fruit and leaves are cooked as vegetable. Also, watermelon juice is fermented to produce an alcoholic beverage. The seeds have a nutty flavor and can be dried and roasted, or ground into flour (Chomicki ,2015).
Taxonomic description of watermelon:
(Unranked) : Angiosperms
1.2 LITERATURE REVIEW
Watermelon (Citrullus lanatus) belongs to the Cucurbit family of vegetables that includes vining garden plants like cucumbers, pumpkins and squash. They require a long warm season to flower and fruit, ideally 80 to 90 days with temperatures above 80 degrees Fahrenheit. Most will flower four to eight weeks from the time of seed germination, depending on the variety planted. Watermelon consists of nearly 100 genera and over 750 species. They are widely distributed in the tropics and subtropics, and a few species occur in temperate region. Watermelon grows well in alluvial and sandy soils even in arid regions and coastal saline areas. Watermelon is a major cucurbit crop that accounts for 6.8% of the world area (second behind tomato) devoted to vegetable production. In 2005, a rough estimate of annual world value of watermelon exceeds $ 15 billion. As per an estimate, the total production of cucumber, melon and watermelon has increased more than four folds in the last 40 years (John et al., 2004).Watermelon is the most popular cucurbits, followed by cucumber, and melon (FAO, 2005).It is originally from Africa and grown in more than 96 countries worldwide, China is the world leader in watermelon production with 70.3% of total production in 2005. Other leading countries are Turkey (4.7%), Iran (2.3%), United States (2.2%) and Egypt (1.7%). India (290,485mt) occupies 26th position in watermelon production (FAO, 2005).
Watermelon is an economically important fruit crop and valuable alternative source of water in desert areas. It is a good source of lycopene, citrulline and important minerals and vitamins. It has the highest lycopene content among fresh fruits and vegetables; watermelon contains 60% more lycopene than tomato ( Al-Khalifa,1996 ) .
Water melon is an annual vine that has a prostrate or climbing habit and the description of the root, stem, leaf, seed, stem and fruit are as follows:
Watermelon root system formation begins prior to emergence of cotyledons to the soil surface and reaches maximum extension by the time of flowering. Watermelon features a highly branching taproot extending up to 1 m deep into the soil,
The stem is a long, trailing vine reaching 5 m and more in length, highly branched; forming secondary side shoots which in turn branch out. The vines, especially the younger shoots, are covered with long, woolly hairs protecting the plant from overheating.
Watermelon leaves are dark green with prominent veins ,they have three large lobes, each further divided into smaller lobes, they are heart shaped with three to seven lobes per leaf and are produced on trailing vines. Leaves are 60 to 200 mm long and 40 to 150 mm and they are large, coarse, hairy pinnately-lobed and alternate.(Al-Khalifa,1996 ) .
Watermelon flowers are yellow having five petals, about 1 cm in diameter. Watermelon vines have separate male and female flowers on the same plant (monoecious) ,they grow singly in the leaf axils and the corolla is white or yellow inside and greenish-yellow on the outside. The receptacle is up to 4 mm long, broadly campanulate and hairy, the lobes are as long as the tube Both male and female flowers are yellow, up to 3-4 cm in diameter.
The male flowers predominate at the beginning of the season and the female flowers, which develop later, flowers are insect pollinated
Fruit shape and appearance are quite varied, ranging from round to cylindrical and a single color to various striped patterns on the fruit surface. The edible flesh is usually pink with many flat, oval, black seeds throughout. Seedless varieties also exist, as well as types with orange, yellow or white flesh. The rind of the fruit is mid- to dark green and usually mottled or striped.
The seeds are numerous, ovate in outline, sometimes bordered; in wild forms they are usually black or dark brown; in cultivated forms they are also white or mottled, mostly 6 - 12 mm long.( George, 2004).
Watermelons are grown from seed. Seedless Watermelons are not actually without seeds, but the seeds are all or mostly immature, white and very soft when the melon is ripe.