Tomato(Solanum lycopersicum L.) is one of the most widely grown vegetables in the world. It is very popular among consumers and is commonly used as a salad vegetable in raw form. The fruits are also processed into juice, ketch-up, sauce, soups, etc. It is the most extensively canned vegetable. Tomatoes form an important source of vitamins A and C in diets.
Interestingly, tomato is one of the newest plants to be used on a large scale for human consumption. It was once believed to be poisonous and was more used an ornamental plant. The perceived poisonous nature of tomato was due to its association with many toxic plants. Tomato is a member of the family Solanaceae, commonly referred to as the ‘deadly nightshade’ family because it has many poisonous members, several of which produce toxic alkaloids. It was only after 1820, when Colonel Robert Gibbon Johnson disproved the myth during a public demonstration in New Jersey; tomato acquired the status of a valuable food item.
Tomato is a short lived perennial plant, grown as an annual, typically growing 1-3 m in height. The stem is weak, woody and the plant usually scrambles over other plants. The leaves are long, pinnate, with 5–9 leaflets, and with serrated margin. Both the stem and leaves are densely glandular and hairy. The flowers are bisexual in nature, off white or yellow coloured, and are borne in groups of 3–12. Tomato is a self-pollinated crop. Fruit size ranges from 2 cm in diameter (cherry tomatoes) to over 15 cm (beefsteak tomatoes). The most widely grown commercial tomatoes tend to be in the 5–6 cm diameter range. Fruit color ranges from yellow to orange to deep red depending on the accumulation of a carotenoid pigment, lycopene. Fruit shape ranges from ovals to plum shaped Italian plum tomato, to pear shaped tomatoes. Fruit flavour also varies from very sweet to highly acidic.
Different types of tomatoes are available for cultivation. Selecting the right variety is critical and should be based considering many factors including the growing condition and market demand. Based on the growth habit, tomato varieties are of three types viz., determinate, semi determinate and indeterminate. Determinate and semi determinate varieties produce stems that end with a flower cluster. Determinates are short and bushy while semi determinate varieties grow slightly taller. Indeterminate varieties continually produce new leaves and flowers, and can grow very tall. Indeterminate varieties set fruit over a longer period. This longer harvest period is an advantage if market prices fluctuate, because income tends to even out. Indeterminate varieties should be staked and pruned and usually require more labour.
Three major market classes are important for tomato viz., fresh market, cherry and processing varieties. The fruits of fresh market varieties are usually red but vary in colour, shape, and size; the cherry types are small fruited (less than 30g) borne on long clusters and used as fresh market type; and processing varieties with fruits having intense red color and high solids content suitable for making paste, ketchup, or sauce.
Origin and distribution
The centre of origin of tomato is South America and the plant is specifically native to the Andes region of Chile, Colombia, Bolivia, and Peru. Mexicans were the first to domesticate tomato, and though cultivated throughout the world, the crop is particularly concentrated in Australia, Central America, and South America.
Tomato is a warm season crop. The best fruit colour and quality is obtained at a temperature range of 21-24°C. Temperatures above 32°C adversely affects the fruit set and development. The plants cannot withstand frost and high humidity. It requires a low to medium rainfall. Bright sunshine at the time of fruit set helps to develop dark red coloured fruits. Temperature below 10°C adversely affects physiological activities. Wide ranges of soils from sandy to heavy clay are suitable for growing tomato. However, well-drained, sandy or red loam soils rich in organic matter with a pH range of 6.0-7.0 are considered as ideal. Tomatoes benefit from crop rotation. However, avoid planting tomato in a field planted the previous season with tomato, chilli, brinjal, or other solanaceous crop as these crops share some pest and disease problems.