Tomato is originated in Peru of South America and name of crop came from the Aztec word tomato. The Tomato was discovered not earlier but in 1544 in Italy. Later spread was fast and the crop is grown throughout world now.
Tomato occupies a prime position in list of protective foods since it is a rich source of vitamins like vitamin A (900 IU), vitamin C (27 mg), vitamin B complex (thiamine), essential amino acids and healthy organic acids like citric, formic and acetic acids. The attractive red colour of fruit is due to lycopene and yellow colour is due to carotenes. Peculiar flavour of tomato is due to presence of Ethanol acetaldehyde and a number of Volatile Flavor components found in fruit. Different forms of tomatine, a steroidal glycoalkaloid, are identified from various parts of plant. Tomato is a good appetizer and its soup is a good remedy for preventing constipation.
Botanical name of tomato is Solanum lycopersicum Genus Lycopersicon is divided into two subgenera
a. Eulycopersicon (Red fruited and self compatible)
b. Eriolycopersicon (Green fruited and self incompatible). Eulycopersicon includes two species, with large fruits and L. pimpinellifolium ( New name Solanum pimpinellifolium) with small fruits born in clusters. Eriopersicon mainly consists of wild sp like L. hirsutum(S.habrochaites), L etc. Rick (1976) divided genus Lycopersicon into following two groups based on their ability to cross with cultivated tomato.
Esculentum complex (crossable with cultivated tomato)
L. esculentum, L. pimpinelifolium, L. cheesemani and L. hirsutum
Peruvianum complex (Not crossable with cultivated tomato)- L. peruvianum, L. chinense.
Solanum lycopersicum S. pimpinellifolium
L. chessmanii L. hirsutum
Based on growth habit and fruit characters, five forms of L. esculentum are identified.
Communae – Common tomato
Cerasiformae – Small fruited cherry tomato
Pyriformae – Pear shaped tomato
Grandifolium – potato leaved tomato
Validum – Erect and upright tomato
Tomato is a true diploid with 2n=24. Plant is annual with herbaceous prostrate stem having determinate or indeterminate growth habit. In the determinate growth, terminal bud ends in a floral bud and further growth in arrested resulting in dwarf and bushy stature. In indeterminate growth, terminal bud is a leafy bud and terminal and lateral buds continue to grow and there are less production of flowers and fruits on main stem.
Flowers are borne in racemose cyme and flower cluster is known as ‘truss’ and its position is extra axillary. Flowers are hermaphrodite, pendulous, pentamerous and hypogenous. Stamens are six in number and inserted on throat of corolla tube and anthers are convent around style.
Tomato is a self pollinated crop due to hermaphrodite flowers, introvert stigma, internal and synchronized anther dehiscence, and stigma receptivity. Self fertilization occurs when pollen grains are shedding during growth of style through anther corn. In warm regions of the country, some amount of crossing was observed when stigma protrudes out the level of anthers.
Tomato is a day neutral warm season crop, which cannot tolerate frost. Cool and dry weather is preferred by the crop and optimum temperature is 21-28oC during day and 15-20oC during night. Night temperature is more critical than day temperature. High temperature results in exerted stigma, dryness of stigma, burning of anther tip, poor pollen dehiscence, low pollen viability and slow pollen tube growth leading to low pollination and fruit set. Incidence of viral diseases also will be more at high temperature. Optimum temperature for colour development of fruit is 21-24oC. Development of colouring pigment, lycopene will be hampered above 27oC. Seed germination and pollen germination are adversely effected below 10oC.Based on night temperature requirement for fruit set, tomato varieties are classified into three.
a) Normal set varieties: Set fruits at 15-20oC.
b) Hot set varieties: Set fruits above 20oC – eg : Philipine, Punjab Tropic, Pusa hybrid 1.
c) Cold set varieties: Set fruits below 15oC – eg : Pusa Sheetal, Avilanche.
Tomato cannot withstand water logging. Hence well drained fairly fertile soil rich in organic matter is preferred. It is moderately tolerant to acid soil having pH 5.5 and ideal pH requirement is 6-7oC.
Sowing time and seed rate
Under mild climatic conditions, where there is no danger of frost, three crops can be raised in a year. In the hills, seeds are usually sown in March-April. In plains is grown during June to November. Under Kerala condition, seeds are sown in September and transplanted in October.
Open pollinated variety: 400-500 g / ha Indeterminate F2 hybrid: 125-175 g / ha. Seeds sown in an area of 4-5 cents (200-240 m2) will be sufficient to plant one hectare. Four to five weeks old seedlings are used for transplanting. Hardening of seedling is essential for their establishment in main field and is done by withholding irrigation for one week before transplanting, adding NaC1 (400 ppm) to irrigation water or by spray of cycocel (200 ppm) and Zinc Sulphate (0.25%) + 25 ppm proline at time of transplanting. Main field preparation and transplanting Seedlings are transplanted on raised beds or on sides of ridges. Field is ploughed 4-5 times and raised beds of 80-90 cm width or ridges and furrows are prepared. Spacing depends on the growth habit (determinate, indeterminate or semi determinate) of variety and various spacing followed are 60 x 30-45cm, 75 x 60cm and 75 x 75 cm. Usually closer spacing results in early and higher yield, but it may effect size of fruits.
Manures and fertilizers
Manure and fertilizer recommendation for tomato depends on the growth habit and productivity of variety and it varies from state to state. In most of states, in addition to 15-20 tonnes of FYM, 100-125 kg, N, 50-60 kg P2O5 and 50-60 kg K2O are recommended for one hectare. Recommendation for F1 hybrid is 250:250:250 kg NPK/ha. FYM should be incorporated in soil at the time of final ploughing. 1/3 N, Full P and K may be applied as basal dose either just before transplanting or 5-10 days after transplanting. Remaining 2/3 N is applied 20 and 45 days there after. In Tamil Nadu, additional dose of 10 kg borax and 5 kg Zinc Sulphate, as basal dose, are also recommended for correcting fruit cracking and to increase yield and fruit quality.
Application of fertilizer
Apply FYM 25 t/ha, N 75 kg, P 100 kg, K 50 kg, Borax 10 kg and Zinc sulphate 50 kg/ha as basal dose and 75 kg N/ha on 30th day of planting during earthing up. Spray 1 ppm (1 mg in one lit) Triacontanol, 15 days after transplanting and at full bloom stage to increase the yield.
Furrow irrigation is the most common method in tomato and the crop require adequate moisture throughout growth period. Frequency of irrigation depends on the climatic and soil conditions. During summer, crop should be irrigated at 3-4 days interval. Water stress at flowering stage will adversely effect fruiting and productivity. A long spell of drought followed by heavy irrigation leads to cracking of fruits. Similarly a dry spell after regular irrigation causes blossom end rot. Drip irrigation and sprinkler irrigation are becoming more common in areas of water shortage.
Field should be kept weed free by frequent weeding, hoeing and earthing up. Application of pendimethalin (1.0 kg a.i. / ha) as pre emergence spray along with one hand weeding at 45 DT is ideal for tomato variety Pusa Ruby. Oxyfluorfen (0.25 kg a.i. / ha) Goal (0.25 kg a.i./ha) and Basalin (1.0 kg a.i. / ha) were also ideal as pre emergence application. Post emergence spray of Sencor (0.5 kg a.i./ha) was also effective at the All India Coordinated trials. Mulching with straw or plastic is also effective for weed control and for regulating soil temperature.
Training and pruning
All indeterminate varieties are trained with wires, strings or stacks to prevent lodging and loss of fruits by coming in contact with soil. It is done by providing individual stack or by erecting 2-2.5 m long poles on either side of ridges for stretching G1 wire. Branches of plants are supported on poles or strings with twine.Pruning is also generally followed in indeterminate varieties to improve size, shape and quality of fruits. It is removal of unwanted shoots to enhance vigor of plants.
Plant growth regulators
Plant growth regulators are beneficial for early yield, increased fruit set at extreme temperatures and to impart resistance to viral diseases. However, their effect is not seen consistent and varied with genotype, climate, location etc. Some of the growth regulators found useful in tomato production are
Crop starts yielding by 70 days after planting. Usually fruits are harvested with hand by a gentle twist so that the stalk is retained on plant. Intervals of harvests depend on season and it is twice in a week during summer and weekly during winter and rainy days. Harvesting maturity depends on the purpose whether for fresh market, processing, long distance transport etc. Following maturity standards are recognized in tomato:
• Mature green: Fruits fully grown, fruit colour changes from green to yellowish and cavity filled with seeds surrounded by gelly like substance. Harvested for long distance market
• Turning or breaker stage: Fruits firm, 1/4th portion of fruit changes to pink in colour, but the shoulder still yellowish green. Harvested for long distance market.
• Pink stage: 3/4th of whole fruit surface turns pink colour. Harvested for local market.
• Light red: Entire fruit surface is red or pink but the flesh is firm. Harvested for local market.
• Red ripe or hand ripe: Fully ripened and coloured. Flesh becomes soft. Harvested for processing and for seed extraction.
Open pollinated varieties : 20-25 t/ha.
F1 hybrids : 50 t/ha.
Grading storage and marketing
Fruits after harvesting are graded and packed in bamboo baskets or wooden boxes. Four grades specified by Bureau of Indian Standards are Super A, Super, Fancy and Commercial. Since tomato is a climatic fruit, good care should be taken to remove bruised, cracked and damaged fruits before packing in baskets. Though tomato can be stored at low temperature, commercially it is not stored in cold storages in the country due to practical reasons. Fruits can be stored for-two weeks and four weeks at 10-13oC when harvested at red stage and green stage respectively. Pre-cooling of fruits before storage and transportation enhances storage life.
Use of tomato for processing is increasing day by day and a variety of products like puree, paste, syrup, juice, ketchup etc are made. Varieties for processing should have following qualities.
• Deep red colour which retains even after processing.
• Low pH – The acidity of fruits affect-heating time required for sterilization of processed product. Longer time is required if pH is high and hence a pH below 4-5 is required for processing.
• High TSS – Fruits with high TSS yield more finished products / tonne of raw fruits and hence minimum TSS should be 4.5oB
• High viscosity and consistency
• Firm and easy peeling
• Pericarp thickness-should be more than0.5 cm.
• Crack resistance
• Fruits size should be above 50 g and oblong in shape Varieties like Pusa Gaurav, Roma, Punjab Chuhara, Pusa Uphar, Arka Saurabh are specially suited for processing.
Fruit cracking is caused both by genetic and environmental factors. Following four types of cracking are noticed tomato.
• Radial Cracking: Usually seen at ripe stage and crack radiate from pedicel end to stylar end.
• Concentric cracking: Seen around shoulder of fruit even at green stage.
• Cuticular: Seen on outer skin of fruit.
• Burst: Burst occurs at certain points on shoulder of fruit. Radial and concentric cracking are more common of which, former is more damaging. A long spell of drought followed by sudden heavy irrigation may cause cracking. Wide variation in day and night temperatures and high humidity also cause fruit cracking. Many crack resistant varieties like Crack Proof, Ohio 832, Sioux, Manulucie, Anagha etc. were developed at various research organizations. Fruits of crack resistant varieties have thick pericarp or cuticle and fruit skin with high elasticity and less acidity. Pectin content in resistant varieties ranges from 0.8 to 1.6% compared to 0.54% in susceptible ones. High pectin concentration makes fruit less rigid and more pliable.
Blossom red rot
Water soaked spots of one cm or more appear at point of attachment of petals and effected portion becomes sunken, leathery and dark coloured. This is mainly due to reduced soil moisture supply and high rate of respiration at the time of fruit development. Deficiency of calcium also causes this disorder. Balanced irrigation, cultural practices to conserve soil moisture and spraying of 0.5% calcium chloride at fruit development stage are recommended for control of blossom end rot.
Sun scald Due to extreme heat, tissues on exposed fruit develop a blistered appearance leading to sunken areas, which have a light or grey colour on green fruit and yellow colour on red fruit. In varieties with heavy foliage, fruits are shaded and incidence of sun scald is less.