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Chromosome Number: 24
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Fabales
Family
:
Fabaceae
Genus
:
Tamarindus
 
Tamarind is an important tree of semi-arid tropical conditions. Every part of the plant is used for different purposes. The fruit pulp, sweetish/acidic in taste, is used for serving curries, chutneys, sauces and soups. Pulp is a carminative and laxative given as infusion in biliousness and febrile conditions. Because of its anti-scorbatic properties, pulp is used by sailers in place of lime or lemon juice. Tamarind kernel powder (TKP) is used as a sizing material in textile and leather industry. The polysaccharide, jellose, in TKP forms jels with sugar concentrates and is an excellent substitute for fruit pectins. Seeds are used as a source of carbohydrates for paper and jute products. Seeds yield a fatty oil which is used in paints and varnishes. Wood is used for making agricultural implements, tool handles, wheels, mallets and rice pounders. Tender leaves, flowers and young seedlings are eaten as a vegetable. In India, it is grown in Bihar, Orissa, parts of Maharashtra and Tamil Nadu. It extends northwards to the sub-Himalayan tract.
   
Climate and soil  
The tree is well-adapted to semi-arid tropical regions, but it can be grown in heavy rainfall areas too, if drainage is provided. It is grown in areas where the temperature reaches 46°C (maximum) and 0°C (minimum). The average rainfall being 500–1,500mm. The optimum elevation of tamarind cultivation is 1,000m above mean sea-level. It is grown on gravelly to deep alluvial soils. It thrives best on deep loamy or alluvial soils. It can tolerate slightly saline and alkaline soils. This crop is also adaptable to poor soils.
 
Varieties

There are only a few varieties of tamarind. Important varieties are:

PKM 1

A clonal selection from the gene bank, it is an early variety yielding 263kg pods/tree with a pulp content of 39%. It can give 26 tonnes of pods/ha if transplanted at a spacing of 10m × 10m.

Urigam

This is another local type providing very long pods having sweet pulp.

   
Cultivation  

Propagation

Tamarind is propagated by seeds, grafts and buddlings. Seeds are sown in lines 20–25cm apart. They germinate in a week. Seedlings should be irrigated if necessary at regular intervals. About 3–4 months old seedlings are transplanted in the mainfield.

Seedlings can also be raised in polythene bags. But true-to-type plants cannot be produced by seed propagation. For true-to-type plant grafts and buddlings are used. Approach grafting is commonly followed in Tamil Nadu. Patch budding is also quite successful. Softwood grafting is successful in tamarind using 6–12 month old rootstocks.

Planting

Planting is done during June–November. Pits of 1m × 1m × 1m size are dug at a spacing of 10m × 10m. Farmyard manure @ 15kg/pit is incorporated with top soil before taking up planting. Regular watering should be given if necessary till the plants establish.

Aftercare

Regular irrigation should be given till the plants are established. Keep the field weed-free during initial stages.

   
Harvesting & Postharvest management
Seedling plants start yielding in 8–10 years, whereas grafts and buddlings in 4–5 years after planting. Harvesting is done during January–April, average yield being 26 tonnes of pods/ha.
TOP
 
Chromosome Number: 30
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Theales
Family
:
Theaceae
Genus
:
Camellia
 
Tea is an important plantation crop. India has 4,36,057 ha land under tea, of which 87,993 ha is in the south. Major tea-growing states are Assam (53%), West Bengal (23.9%), Tamil Nadu (11.3%) and Kerala (8.44%). Tea is also grown on a small scale in Tripura, Karnataka, Himachal Pradesh, Uttar Pradesh, Sikkim, Bihar, Manipur, Orissa, Nagaland and Arunachal Pradesh. The tea industry in India is more than 150 years old, generating a revenue of Rs 6,000 crore. It employs more than 1 million workers directly and looks after 4 million dependants of these employees. Of the working population directly employed by the tea gardens, nearly 50% are women. The production of tea in India has increased from 250 million kg in 1947 to 754 million kg in 1991 and to 805 million kg in 1999 with just 40% increase in area.
   
Climate and soil  

There is a considerable difference in the terrain of the tea-growing areas of south and north-east India. In Brahmaputra valley, tea is cultivated on flat lands at elevations of 50–120m above mean sea-level. These alluvial soils are generally deep, fertile, have a good water-holding capacity and respond well to manuring. Some soils in the north bank are poor and sandy. But there are also a number of small pockets of old red soil which are mostly rich loam.

The annual rainfall varies from 210–290cm. The monthly average maximum temperature varies between 22 and 28°C during October–March, but it may rise up to 37°C between April and September. The minimum temperature usually does not go below 7°C.

In the Barak valley, tea is grown in small hillocks and to some extent on the plains adjoining the hillocks. The soils here are peaty which are rich in organic matter. The soils of flat lands vary in texture from sandy to heavy clay. The clay minerals are predominantly kaolinitic with some illite and montmorillonite and are in various stages of laterization. The annual rainfall though varies from 300 to 500cm, distribution is uneven and severe drought is a usual feature in the winter season.

In the Dooars and Terai in the south of the Himalayan foothills in West Bengal, tea is grown 80–380m above mean sea-level. Most of the soils in Dooars are old red, well-weathered, rich loamy, deep and acidic. The Terai soils are deposited as a result of their movement through water erosion. The lower strata of stones and gravel of miscellaneous rocks had moved from the hill ranges. The soils are highly productive if drainage is proper.

In the eastern Dooars, soils are sandy loams. This area receives 300–500cm of rainfall in a year but again distribution is uneven and drought is common during winter months.

In Darjeeling, tea is grown on sedimentary soils in the hill slopes at elevations of 600–2,000m. The temperature in these hills does not usually exceed 25°C. During winter, the temperature dips to about 5°–6°C. Unlike in the other regions, winter is very cold and dry, and at higher elevations, snowfall and frost may occur.

Tea plantations in Kangra valley in Himachal Pradesh are also situated on the mountain slopes, but those in the Dehra Doon area are on almost flat lands.

In south India, tea areas are located on the hilly terrains. About 31.8% of the tea areas in south India are at an elevation of 1,000m, 34.5% between 1,000 and 1,500m, 25.7% between 1,500 and 2,000m and 8.2% above 2,000m. The tea soils here are Latosols. Kaolinite is the dominant clay mineral. The soils have undergone considerable weathering and contain large amounts of sesquioxides and hence phosphorus fixation is very strong. In most of the areas like Valparai (Anamallais) and Idukki (High Range and Central Travancore) soils are open in texture, coarse and fine fractions comprise 62–67% of the soils. The soils of Wynaad and Nilgiris are of clay loam type with a preponderance of clay fraction. The advantage of having higher amount of organic matter in the Nilgiri soils is to a certain extent offset by the disadvantages of clay. The average rainfall in the Nilgiris is 170cm. The western portions of the district such as Ooty and Kundha lie within the full influence of south-west monsoon. In eastern portion consisting of Coonoor, Colacumbie and Kotagiri, the rainfall pattern is different and it receives more rain during the north east monsoon. In the majority of the area, cool and dry weather prevails for most of the year and during winter, many tea estates experience temperature below zero. Frost is a recurring phenomenon in the Nilgiris.

The tea growing areas of Animallais (Valparai, Coimbatore Dist.) receives rainfall during the south-west as well as the north-east monsoons. Most of the tea gardens are located at altitudes ranging from 1,000 to 1,200m. The average annual rainfall is 400cm. The mean maximum temperature is below 30°C.

Tea in the High Range (Devikolam, Idukki Dist.) is grown at elevations 900–2,600m. There is considerable variation in the rainfall pattern. On the north-eastern edge of the High Range, the average rainfall is about 150cm whereas in the estates at the foot of Anaimudi, the highest peak in the western ghats, the average annual rainfall is 630cm. Being a high elevation area, the region experiences very low temperature and frost regularly occurs in some pockets. Though the maximum temperature is in the region of 25°C, minimum temperature during winter may come down even to 1 or 2°C.

Unlike in the High Range, the tea areas of Central Travancore, though located in the same district (Idukki) experience comparatively high maximum temperature (about 32°C). The annual average rainfall is 170cm but the district is highly prone to drought.

The regions of Wyanad, Gudalur and Karnataka are unique in that they enjoy an annual precipitation of 250cm, bulk of its falling in 3 months with an average of 140 wet days and 110 continuous rainless days. The maximum temperature is probably highest in these areas, Chikmagalur in Karnataka touching as high as 39°C.

The cultivated tea near to equator produces almost the same yield throughout the year, but further from the equator, harvest in winter gradually declines and at latitudes beyond about 16°, there is complete winter dormancy, the length of dormant period increases progressively with increasing distance from the equator.

 
Varieties

From the very early days of tea cultivation in India, seeds were used for planting and it remained so for over 120 years. The use of vegetatively propagated plants was started in 1949 after the release of clones by Tocklai Experimental Station. Tea being a highly cross-pollinated crop, the seedling populations are highly heterogenous and comprise a large number of genetically distinctive genotypes which can be grown in a wide range of agroclimatic conditions. Unlike the seedlings, the clonal populations behave almost like a single bush. Germination of seeds is not affected by the soil conditions and the seedlings are comparatively easy to grow. The genotypic and phenotypic variability of seedlings is high. For the propagation of clonal plants, the nursery techniques will have to be fine tuned and their rooting is greatly influenced by the soil texture, pH and a number of other factors. Fields planted with seedlings generally give only average yields and quality. But these plants are more tolerant to drought and to infestation by pests and diseases. Their nutritional requirements are also rather moderate. The vegetatively-propagated plants are generally high yielders with good quality parameters and naturally the nutritional requirements are also high. Clonal plants are not deep rooted, and become easily susceptible to drought. Since they are generally screened against major pests and diseases, they may exhibit a certain degree of tolerance to these biological stresses. However, under certain circumstances some of these clones may become highly susceptible to infestation by a specific pest or disease.

New cultivars are selected from the existing seedling populations or by hybridization, polyploidy, mutation or genetic engineering. The genetic base of our tea plant population should be broad-based and, therefore, a policy of clone-seed-clone-seed cycle is preferred. The Tocklai Experimental Station has so far released 29 TV series clones, over 130 TRA/garden series clones, 100 industry clones and 9 Tocklai biclonal seed stocks. For use in south India, the UPASI Tea Research Foundation Valpiroi, has released 28 clones, about a dozen estate selections and 5 biclonal seed stocks. The UPASI TRF has also developed 7 nursery graft combinations using high-yielding clones as scions and drought-hardy clones as rootstocks.

   
Propagation

Commercial nurseries and seed gardens supply vegetatively propagated plants or seeds. However, it would be advisable that the estates establish their own seed gardens and nurseries to obtain good quality planting material of their choice. The seed beries should not be in drought-prone areas and should be at least 20m away from tea fields. The parental clones should be planted as per the approved design and manured as per the recommendations. The plants will start flowering and fruiting from the third year after planting and seeds may be harvested when they become brownish. The empty seeds may be discarded and the heavier ones retained. Finely powdered charcoal may be used to preserve seeds for a short duration but seeds preserved for a long time fail to germinate. Seeds put out in the nursery beds germinate within 30 days and the seedlings may be transplanted to polythene sleeves and provided with a polythene cloche. The seedlings become ready for planting after 9 months.

The vegetatively propagated nersery should be situated close to a water source. For raising 1,00,000 plants at a time and hardening them, an area of 1,500m2 land is required. The composition of soil and sand mixture used in the nursery and their soil pH and electrical conductivity are important. The rooting medium should be sandy loam texture and contain subsoil and sand in a 1:1 ratio. The growing medium must be of clay texture, containing jungle or top soil and sand at 3:1 ratio. The pH should be 4.8–5.0. If the pH is higher than this, the medium should be treated with 1 or 2% aluminium sulphate, depending on pH. The soil used in the nursery should be free from nematodes. The cuttings calluse in 4–6 weeks and rooting takes place in 10–12 weeks. The plants with good root system may be sorted out and manured with the soluble nursery mixture. They could be kept under overhead shade for 1 or 2 months and gradually exposed to direct sunlight.The plants can be fully exposed for 4–6 months when about 6 months old. The 9–12 months old plant becomes ready for planting in the field.

   
Cultivation  

Planting

In olden days, up and down style of planting was practised in south India and this practice could accommodate around 6,800 plants/ha. Currently, single or double hedge style of planting is recommended. In south India, where tea is grown on slopes, 1 ha of land planted in single hedge may contain 19,800 plants, whereas in the double hedge style, there are 13,200 plants.

In north-east India, the planting density varies from 14,000 to 17,000 bushes/ha. The minimum space required between plants is 60cm and between rows 105cm. The double hedge planting has an initial advantage over single hedge for 7–10 years and subsequently single hedge has advantages in terms of frame formation, yield and convenience of cultural operations. The dimensions of planting pits are 30 × 45cm in south India and 45 × 45cm or 60cm in north-eastern India.

The bringing up of young tea is an important aspect and is achieved through a series of operations such as decentering, thumb pruning, debudding and frame forming pruning in north-eastern India. In the south, these operations are rather simple. The leader stem of the young plants is cut 4–6 months after planting, leaving 8–10 leaves below the cut. Later, these plants are tipped at 35cm height and second tipping will be at 50cm. After this, bushes can be brought under regular plucking. The young plants can be manured two months after planting. They should be mulched and protected against drought, pests and diseases. In south India, young plants are subjected to formative pruning in the 5th or 6th year from planting.

Pruning

Tea bushes are pruned at periodic intervals to revitalize their vegetative vigour, regulate their height and for good yield of crop. It is also aimed at developing good frames. Thus, pruning carried out occasionally is a critical operation. Pruning removes substantial amount of leaves and branches and the dormant buds on the stems left at the time of pruning are stimulated to grow and establish a shoot system with vigorously growing shoots. Pruning aids in maintaining the bushes permanently in a vegetative phase. As the age of the bush advances from pruning, the area of plucking table increases as also the density of plucking points. The proportion of banji shoots also increases progressively from the year of pruning to the next pruning. There is also a direct relationship between pruning and drought stress. Water requirement of older fields is higher and drought stress is more pronounced in such fields. Pruning helps in overcoming the drought effect; it also exposes the bark of frames which had been shaded for a few years. The plucking table continues to rise as the age from pruning advances and pruning assists in keeping the height of the bush within the bounds of easy and efficient plucking. Also pruning before the high cropping season facilitates better distribution and effective management of crops.

Generally, a 4-year pruning cycle is followed in the mid elevation areas and 5-year cycle at high elevations. Pruning is carried out during the pre-monsoon or post-monsoon periods since adequate soil moisture is a pre-requisite for pruning. A pruning height of 30–40cm is termed a hard prune while medium style of pruning refers to pruning between 45 and 55cm. When primary frames are healthy and if secondary branches have numerous knots and are cankered, a hard or medium pruning becomes necessary. In such cases, pruning is done into the secondary wood.Cleaning of branches which are less than pencil thick in diameter and removal of snags is often undertaken while carrying out this type of pruning.

When bushes are pruned at a height between 60 and 70cm, it is referred to as light pruning. This can be adopted if the primary and secondary branches are healthy. Cleaning of branches is not recommended in this style of pruning. In other words, only a cut across at the prescribed height is given. If the bushes are pruned about 75cm, it is referred to as skiffing which is the lightest form of pruning. The criterion for determining the height of pruning should be the thickness of branches. Good frames could be developed with correct tipping. Once healthy, secondary and tertiary branching systems are established, 3–4 cut across prunes between 60 and 70cm may be inserted. After 3 or 4 such cut across prunings a low cut at 45–50cm becomes necessary. While pruning practices adopted in most of the tea growing areas of the world are more or less similar to that described above, the system adopted in north-east India differs considerably.

In plains of north-eastern India, tea is pruned every year when bushes enter the dormant phase. Though this method is no longer practised, bushes are cut very lightly every year and this is called skiffing. Nowadays, certain estates do not do skiffing every year and leave the bushes unpruned for 2 successive years. At the end of the pruned year, the bushes may be skiffed deep, medium, light or level. Skiffing may be repeated for 2–6 years. Deep skiffing is given at a height mid-way between pruning and tipping levels. In medium skiff, the cut is nearer to the tipping height, say 5cm below the tipping height. Bushes which have been light or level skiffed are not tipped. The introduction of skiffing in place of pruning in north-eastern India has helped to increase the productivity. However, skiffed bushes are more prone to drought and they get heavily infested by pests such as red spider mite and tea mosquito bug.

The recovery of bushes after pruning depends on the height of pruning, type of wood, time of pruning, health of bushes, carbohydrate reserves and elevation of the garden. The aperiodic shoots developing on frames of pruned bushes are tipped at an appropriate height. Height of tipping decreases with increasing height of pruning. The first plucking of recovering bushes is called tipping. The objective of tipping is to establish a level plucking surface, to provide adequate maintenance foliage and for the quick production of secondary branches.

Manuring

Manuring of tea enhances vegetative growth to harvest growing points without affecting bush health and to suppress the reproductive phase. Manuring constitutes 17–24% of the total input and hence should be used judiciously. The increase in productivity due to sound manurial practices is 20–25% while the cost of manuring is only 6–10% of the total cost on tea production. While the basic principles of manuring are the same, the optimum fertilizer application varies from region-to-region and even from one field to another, depending on the local conditions.

Tea being a leaf crop, nitrogen content of the flush shoots is the highest followed by potassium, calcium, phosphorus, sulphur and magnesium. In addition to these, zinc, which is continuously removed at every harvesting, is limiting in the tea soils. Foliage and stems are added to the soil at the time of pruning and nutrients on them are recycled. Similarly, leaf litter and loppings from the shade trees also enrich the tea soils. From the total dry matter produced in a pruning cycle about 10% diverted to flush tea shoots, 18% to mature foliage, 12% to twigs, 35% to thick wood and 25% to roots.

Made tea contains approximately 5% N, 1% P 2 O 5 and 2% K 2 O and an average crop of 2,000kg made tea/ha removes 100kg N, 20kg P 2 O 5 and 40kg K 2 O/ha/annum in addition to a large amount of nutrients being locked up in the bushes.

Nitrogen: Nitrogen in a healthy tea plant, and nitrogen level in the flush shoots is between 3.5 and 5.0% of the dry matter and below 3% deficiency symptoms appear. Nitrogen deficiency is shown by yellowing of leaves, retardation of growth, formation of small leaves and short internodes. Tea plants are able to use either nitrate or ammonium ion but the latter is preferred.

Under favourable circumstances, the yield response commences 3–4 weeks after the application of nitrogen fertilizer. In different regions of north-eastern India for sustaining an yield of about 2,300kg made tea/ha, 100–140kg N/ha would be sufficient and for a productivity level of 3,500kg/N or more, 160–168kg N/ha would be sufficient along with phosphate and potash. In Kangra valley, a uniform recommendation of N:P 2 O 5 :K 2 O::90:90:90 kg/ha had been made for yield levels between 1,000 and 1,500kg made tea. In south India, the dosage of N is determined on the basis of anticipated yield and organic matter status of the soil. In this scheme, the rate of N varies in the different years of the pruning cycle depending on the yield trend and the yield built up in the successive pruning cycles. For tea soils with low/medium/high organic matter status 12/10/9kg of N/100kg of made tea is recommended for yield up to 2000kg/ha. At and above 2,100kg made tea/ha, additional N at 5/5/4kg/100kg of made tea is recommended for low/medium/high organic matter status. Sulphate of Ammonia (SOA) is the best source of N throughout the year. Calcium ammonium nitrate (CAN) is the best source of N for winter in south India. Urea is the cheapest source of N and therefore, a greater portion of annual N is met by urea during moist soil conditions. In south India, SOA is superior to CAN which is superior to urea.

The efficiency of nitrogenous fertilizers can be increased by split application of the annual nitrogen. However, in north-eastern India, application of N up to 4 splits had not shown any advantage over single application where 90 and 135kg N/ha were applied. In south India, total N is divided into 4–6 splits depending on the rate of N. Fertilizer N is generally broadcast. Foliar application is also considered very efficient under certain conditions. However, full nutritional requirement of tea cannot be met solely by foliar application. It can only supplement soil aplication, when roots are unable to absorb sufficient nutrients due to drought or waterlogged conditions. The optimum oncentration of urea for foliar application is 1–2% and should be sprayed on the day following plucking.

Potassium: Potassium is a major nutrient for tea. The K content of flush shoots is 1.5–2% of the dry matter and the critical level is around 0.7%. Its deficiency leads to a gradual decline in the yield. Marginal necrosis of mature leaves, premature leaf fall, development of thin and twiggy wood and ultimately the death of bushes are its symptoms. In north-eastern India, 80–140kg of K 2 O/ha is recommended for sustaining yield of 2,000kg/ha and to get 3,500kg/ha of yield or more 160kg of K 2 O/ha along with N and P is needed. In south India, the significance of NK interaction was recognized as early as 1950 and the emphasis had been on adequate application of K along with N to maintain high yield in different years of pruning cycle. It is now recommended that N:K 2 O ratio for young tea is 2:3 up to 3 years and 1:1 thereafter. In pruned year, N:K 2 O ratio depends on the height of pruning. For a pruning height below 45cm, N:K 2 O ratio should be maintained at 1:2, between 45 and 60cm at 2:3 and above 60cm, it should be maintained at 1:1. In other years of the pruning cycle, the recommended N:K 2 O ratio for sulphate of potash is 2:1 and for urea and CAN, the ratio is 4:3.

The foliar application of urea and MOP imparts drought tolerance in young and mature tea. About 4–6 foliar applications of urea and MOP, each at 1% concentration, at monthly interval during the dry period helps maintain turgidity of cells, reduce proline content, enhance carbohydrate reserve, reduce banji shoot formation, improve water-use efficiency and enhance the yield.

Phosphorus: It is one of the essential nutrient elements that could be limiting in the acidic tea soils. On an average, normal P content of flush shoot ranges from 0.18 to 0.39% of dry matter and the P content below 0.18% is critical. P deficiency is characterized by dull bronzing of recently matured lower leaves with or without brown spotting and loss of glossiness. The stems become thin and the internodes of shoots become shorter and finally shedding of leaves, occasionally leading to the death of plants. The use of rockphosphate is recommended for reasons of economy. In Darjeeling area, generally 20kg of P 2 O5/ha and for Assam 50kg of P 2 O 5 /ha is recommended along with N and K for sustaining an yield of about 2,300kg made tea/ha. In south India, application of rockphosphate is recommended on the basis of soil availabe P and yield level. For yield up to 3,500kg, 60–80kg of P 2 O 5 /ha is recommended, if soil P is below 22ppm. Similarly, for yields 3,500kg made tea/ha, 80–100kg of P 2 O 5 /ha is recommended, if soil P is below 44ppm. In south India, broadcasting of P in tea soils had been found ineffective and therefore placement in holes is recommended. This reduces its fixation and creates a concentration gradiant which helps in the movement of P and better utilization by exploring roots. To meet the nutritional requirement of P, soil application of P in alternate years is supplemented by annual foliar application of DAP. The recommended rate for foliar application is 10kg P 2 O 5 /ha/year in 5 splits at monthly interval. The most suitable source for foliar application is DAP and the rate of DAP is 22kg/ha/year. For each foliar spray, 4.4kg of DAP in 250 litres of water/ha may be used, the DAP may be applied either alone or mixed with acaricides during periods of mite incidence.

Calcium: Tea requires fairly low amount of Ca. On an average, normal CA content of flush shoot ranges from 0.3 to 0.9% of the dry matter. Its level below 0.6% in the maintenance foliage is reported to depress the crop. The deficiency of Ca is characterized by brittle old leaves and young leaves with discoloured laminar edges which later become dark brown. On the other hand, its excess in soils slows down the growth of plants. Young leaves become yellow, curl inwards with edges and tips turning black and in most severe cases the bush defoliates. Use of nitrogenous fertilizers and heavy rainfall brings down the soil pH in course of time. The pH between 4.5 and 5.0 is optimum for calcium nutrition of tea. In strongly acidic soils with pH below 4.0, hydrogen or aluminium ions interfere with the uptake of potassium. The uptake of K is also inhibited by excess Ca in soil, especially above pH 6.0. Tea plants growing in soils with pH above 6.0, have a tendency to flower profusely. The pH of tea soil is amended once or twice in a pruning cycle by applying dolomitic lime. Liming is recommended only for mature tea plants which are under regular plucking. It is not suggested for areas to be replanted or for young tea fields. Application of lime improves the soils structure by flocculation, by promoting crumb structure, desirable for aeration of the soil. It increases the availability of P by reducing the solubility of iron, aluminium and manganese which relieves P from insoluble forms. Nitrifying bacterial activity is enhanced by liming and thus organic matter decomposes better.

In north-eastern India, 2 and 3 tonnes of dolomite is recommended for coarse-textured and fine-textured soils, respectively. If the pH is less than 4.5, the rate of application of dolomite is reduced to 1–1.5tonnes/ha for coarse and fine textured soil with pH ranging from 4.5–4.65. The rate of application of dolomite in south India is decided on the basis of pH, rainfall, yield and length of the pruning cycle. However, the maximum quantity of dolomitic lime in an application should be restricted to 4 tonnes/ha. Lime application should be avoided during dry months.Liming materials do not move laterally and therefore, should be uniformly broadcaste over the soil. There must be a minimum of 4–6 weeks interval and 15cm rainfall between lime application and NK manuring and vice-versa .

Shading

Conventionally, tea is grown under shade trees in India. The beneficial effects of shade trees in tea fields have been well realized. These trees help to regulate temperature and humidity at bush level. They minimize the loss of water through evaporation and transpiration. They help to reduce the injury caused to tea leaves by UV radiation. They also help in minimizing soil erosion and increase the fertility of soil by adding 8–10 tonnes of organic matter/ha/year. However, there are a few disadvantages such as the reduction in response to applied nutrients. Shade trees with a shallow root system compete with tea plants for soil moisture and nutrients. Dense shade increase the incidence of blister blight disease in south India. In north-east, trees recommended for permanent shade are Albizia chinensis, A. odoratissima, A. lebbek, Acacia lentiartaris, Derris robusta and Dalbergia sericea. In south India, Grevillea robusta is the only tree recommended for permanent shade. Initially they are planted at 6m × 6m and later thinned to 12m × 6m after 8–10 years of planting and finally into 12m × 12m by 12–15 years from planting. They are pollarded at 8–9m allowing 3–4 tiers of branches below the point of pollarding. They are subjected to annual lopping before the onset of monsoon. The erect branches are lopped, retaining the laterals.

Weed control

Weeds are responsible for considerable loss in crop. It is estimated that while dicots can cause about 12% loss in crop, grasses are responsible for nearly 21% crop loss. Weeds compete with tea for nutrients and moisture; grasses take away large quantities of potassium and deprive tea plants of this major nutrient. Many of the weeds serve as alternate hosts of insect pests of tea. Weeds are a problem mainly in the new clearings and pruned fields. It is necessary to control them till the tea bushes cover the field. Some of the most common, perennial and persistent grasses are Axonopus compressus, Cynodon dactylon, Digitaria adscendens, D. sanguinalis,Imperata cylindrica, Panicum repens, Paspalum conjugatum, P. scrobiculatum and Pennisetum clandestinum. In addition to these, Azonopus affinis, Digitaria longiflora, Eleusine indica, Eragrostis nigra and Setaria glauca are also commonly seen weeds in tea fields. Some of the broad-leaved weeds which are problematic in tea fields are Achyranthes aspera, Borreria articularis, B. latifolia, Commelina sp, Conyza ambigua, Crassocephalum crepidiodes, Sida rhombifolia and Polygonum chinense. The other common broad-leaved weeds that come up easily after controlling the grasses are Ageratum conyzoides, Bidens biternata, Borreria ocymoides and Polygonum ripens.

Weed control assumes considerable significance in view of the ability of weeds to cause heavy crop loss. Currently weed control in tea is achieved by the use of paraquat dichloride, 2,4-D and glyphosate. Paraquat (24%) is recommended at 1.12–2.25 litres/ha depending on the level of weed infestation. The translocated herbicide, 2,4-D (sodium salt 80%) is recommended at 1.4kg/ha along with a non-ionic wetting agent whereas the amine salt (72%) is to be applied @ 1.5litres/ha. Glyphosate can be used in young as well as in mature tea fields. Depending on the weed composition, it is recommended @ 2–3litres/ha. However, the dosage could be reduced to 1.75 litres/ha if used in combination with 2,4-D sodium salt (1.40kg of formulation) and 0.5 litre of non-ionic wetting agent. The volume of water recommended for weed control in tea fields is 450 litres/ha.

Irrigation

Tea is a rainfed crop, therefore, scope for irrigation is rather limited. There is definite increase in crop due to irrigation, either by sprinklers or by drip systems. Measurements have shown that the average loss of water from a south facing surface is 25% higher than from the north facing surface. The wetting depth of irrigation should be minimum 30cm since more than 50% of the feeder roots are located at the lop 30cm of the soil. The quality of irrigation water depends primarily on its silt and salt contents. The electrical conductivity should be below 0.25dS/m for irrigation in mature tea and the residual sodium carbonate should be below 1.25%. The quantity of water required for irrigation depends upon the porosity of the soil, water-holding capacity and infiltration rate. The rate of application should not exceed the infiltration capacity of soil (8–18mm/hr for silty clay loam, 8–10mm/hr for clay loam, 10–12mm/hr for silty loam, 12–14mm/hr for sandy loam and 14–18mm/hr loamy sand or sand). On steeper slopes the rate of application of water must be reduced compared to gentle slopes. Irrigation should be stopped when puddles begin to appear. Based on these factors, the field water requirement and irrigation intervals can be determined.

In tea, sprinkler irrigation is the most common. However, the wind velocity in the fields should not exceed 15mph, if sprinklers are to be employed. It is preferable to irrigate in the early morning or night when winds are mild. The sprinkler system has revolving nozzles operating on varying speed and the rate of irrigation is in the range of 5–15mm/hr. For application of 2.5m of water in 1 ha, 55,945 gallons of water is required. In drip irrigation system, water is applied drop by drop. This system requires large initial investment. However, recent experiments have shown that drip irrigation is suitable for areas which are newly planted or replanted.

Drainage

Drainage is as important as irrigation in north-eastern India. In many areas, watertable at depths of 60cm or more below the surface may cause damage to tea plants. In areas which are not planted in contours, drains are necessary. The common sources of excess water are high rainfall, seepage from high lands, artesian flow or a combination of any two or more of these factors. Many estates have an open drainage system which is becoming inadequate under the changing environmental conditions of siltation of main rivers and floods. Estates which face serious problems of waterlogging require an elaborate network of bigger, deeper and closer drains. Pumping combined with gravity flow is required in areas where gravity flow alone cannot keep the groundwater below the effective root zone of tea plants. Open drains occupy large amount of space, their banks get eroded and maintenance is costly. Under such situations, subsurface pipe drainage system could be considered, even though the initial investment will be high.

   
Harvesting & Postharvest management

Harvesting is most important cultural operation which influences yield, productivity of labour and quality of tea. More than 70% of the labour force in any garden is deployed for this work. Harvesting in tea involves the regular removal of young shoots comprising an apical bud and 2 or 3 leaves, immediately below it. The shoots arising from the sticks (frame) of pruned bushes are called primaries. On these aperiodic shoots, leaves expand in succession without any temporary cessation of growth. When these aperiodic shoots or primaries grow above a predetermined height, they are cut or tipped. The branches of primaries are the first order laterals which when plucked give rise to the second order laterals. These again produce the third order laterals. When the crop shoot is harvested, generally the bud on the axil of the top most leaf of the stem develops into a new crop shoot. During the development of this bud, first 2 scale leaves (cataphylls) or ‘janams' appear. Above the scale leaves or janams is the smooth ‘fish leaf'. This is followed by a series of 3 or 4 normal leaves, the first of which is called the mother leaf. Shoots may be plucked above the janam, fish leaf or mother leaf. These systems of plucking are known as janam plucking, fish leaf plucking and mother leaf plucking, respectively. In north-eastern India, janam plucking is the most common practice. However, in south India, continuous scale leaf or fish leaf plucking is not adopted. An integration of different plucking systems is considered essential to retain the optimum load of maintenance foliage on the bush. Tea shoots are plucked to the level (janam or fish leaf) during April–December and a new tier of leaf is added to the bush by resorting to mother leaf plucking from January to March. Plucking round is the number of days between 2 successive pluckings. In north-east India, this may vary from 4 to 14 days although 7 days round is the most common. The number of days taken for unfolding of successive leaves (1 leaf+bud in 2 leaves+bud) is called phyllocron or leaf expansion time. This depends on the altitude, age of bushes from pruning, height of pruning, jat of tea, etc. In north-eastern India, 2 standards of plucking are adopted. When black plucking is adopted all 1+buds, all 2+buds and single banjis are removed. In standard plucking, large 1+buds, all 2+buds, all 3+buds and single banjis removed. A long-term policy of standard plucking is superior to black plucking under the agro-climatic conditions of north-east India. In south India the practice of plucking differs considerably from that adopted in the north-east.

Harvesting should be carried out when shoots attain maximum weight, without compromising on quality. Targeting for about 85% leaves and a bud and pegging down the immature shoot component to less than 5% is considered optimal to get maximum benefit. The climatic conditions in south India force growth into 2 impulse periods from April to June and again from mid-September–November. About 60% of the total crop is harvested in this period and availability of workers becomes a serious constraint to invest the crop completely. It is now recommended to use handheld shears to harvest the crop during these high cropping seasons. Use of shears is advised only to the high cropping periods and that too for fields which are more than 18 months old from pruning. Continual shear harvesting is proved to depress the crop and adversely affect the bush physiology.

Processing

The harvested green tea shoots are transferred to the factory to manufacture black tea either by the CTC (Crush, Tear and Curl) or the orthodox method. The first step in processing of black tea is withering. The main objective of withering is to remove about 15–20% of moisture from the leaves. During this the leaves undergo physical and chemical withering. Leaves are withered in troughs for about 12–18hr. When leaves have been withered correctly, it becomes flacid and suitable for rolling during which polyphenols are mixed with enzyme polyphenol oxidase (PPO). The leaves are first passed through the green leaf sifter to remove extraneous matter such as stones, bits of metal etc. Green leaves are then shredded into small bits in a shredder before sending them into the rotorvance. Inside the rotorvance the leaves are crushed and discharged through the diaphragm. The ‘dhool' is then passed through 4–5 CTC rollers. The RPM of rollers play an important role in the production of leaf or dust grades of tea. The ‘dhool' coming out of the CTC rollers is ‘fermented'. In tea processing, fermentation is the term employed to denote enzymic oxidation, by which the polyphenols in the leaf get oxidized with the help of PPO. The end product of fermentation are the aflavins and the arubigins which are responsible for the briskness, brightness and colour of tea liquor. Fermentation may be carried on a flat surface (floor fermentation) or in drums. The latter is mostly followed in CTC manufacture. At present, continuous fermenting drums (CFM) are also used. Generally, in south India, fermentation is done for 60–90 minutes.

The keeping quality of tea largely depends on the drying technique and final moisture content in made tea. The objective of drying is to stop the biochemical changes and to remove the moisture. During drying, moisture is removed from the fermented ‘dhool' and its colour turns to coppery red to black and fermentation is arrested. Generally, fermented dhool contains 55–60% moisture and made tea contains 2.5–3% moisture. Drying is carried out in conventional driers, fluid bed driers, vibro fluid bed driers or a combination driers. The total drying time in conventional driers is 20–22 minutes. The inlet and exhaust temperature may be maintained at 100°C and 55°C respectively. From the dried tea, fibre is extracted and the tea is sorted into different grades such as Flowery Pekoe (FP), Pekoe (PK), Broken Orange Pekoe (BOP), Red Dust (RD), Super Red Rust (SRD), Super Fine Dust (SFD) etc.

In orthodox type of manufacturing, processes involved are withering, rolling, roll breaking, fermentation, drying and sorting, and grading. After withering, leaves are rolled in rollers, as if the leaf is rolled between the palms of 2 hands. After rolling for 30–45 minutes the leaves are passed over a sifter which helps in separating the well-rolled leaves or fines. The fines extracted after each roll are spread on racks or floor to ferment. Duration of fermentation varies from 2 to 3hr. The fermented material is dried in conventional driers and sorted and graded. The black tea or made tea is sold loose or in packets, under different brand names.

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Chromosome Number: 24
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Solanales
Family
:
Solanaceae
Genus
:
Solanum
 
Tomato is most important and remunerative vegetable crop in India. A rich source of minerals, vitamins and organic acids, tomato fruit provides 3–4% total sugar, 4–7% total solids, 15–30mg/100g ascorbic acid, 7.5–10 mg/100ml titratable acidity and 20–50mg/100g fruit weight of lycopene.Uttar Pradesh, Maharashtra, Karnataka, Bihar and Orissa, are major tomato-growing states in India.
   
Climate and soil  

Tomato, a warm-season vegetable, is grown extensively in cool season also. The optimum temperature required for its cultivation is 15°–27°C. At high and low temperatures, there is low germination of seeds, poor plant growth, flower drop, poor fruit set and ripening. At high temperatures, generally the quality of fruits is poor and there is high incidence of sun-scald. Under extreme high and low temperature conditions, the yield and quality of fruits is reduced. Mild winter condition in northern plains is ideal for seed germination, plant growth, fruit set, fruit development and ripening. Excessive rains adversely affect its fruit set causing flower drop.

Tomato is grown in varied types of soil—sandy loam to clay, black soil and red soil—having proper drainage. However, sandy loam, rich in organic matter is ideal for its cultivation. The pH of the soil should be 7–8.5. Tomato can tolerate moderate acidic and saline soils. In red and black soils of Karnataka, Maharashtra and Madhya Pradesh, tomato hybrids are cultivated commercially.

 
Varieties
A large number of tomato varieties have been developed in the country. More than 25 open-pollinated varieties and 10 hybrids have been released at the national level. Besides, several open-pollinated varieties and hybrids have been released at state level.
   
Cultivation  

Raising seedlings

For raising the seedlings for one ha, 250m 2 area is required.Generally, in rainy season 7.5m × 1.2m × 0.1m beds are prepared. The beds are covered with a layer of farmyard manure and sand mixed in equal proposition. The farmyard manure should be used @ 4kg/m 2 . During summer and rainy season, there is very heavy incidence of damping off. To protect seeds and seedlings, the beds should be treated with 10% formaldehyde. Before sowing, the nursery beds should be drenched with 0.2% Dithane M-45 or treated with Difolaton or Captan. Solarization is also useful to reduce the incidence of damping off. The seeds should be treated with Thiram or Bavistin @ 2 g/kg. Soon after sowing, the beds should be irrigated with rose can and covered with paddy straw.The beds should be irrigated everyday morning. Seedlings are ready for transplanting 4–5 weeks after sowing. Before transplanting, seedlings should be treated with insecticides 0.1% Nuvacron and Dithane M-45, 0.2%. Hardening of seedlings before transplanting is essential for better setting in the field. Hardening is done by withholding water 4–5 days before uprooting seedlings. Adding 4,000ppm sodium chloride or spraying of 2,000ppm CCC is effective for hardening of seedlings.

Direct seeding

Tomato is also cultivated by direct seeding. It results in early flowering, early fruiting, early yield and less incidence of pests and diseases. Close spacing has the advantage of higher yield by direct seeding. In California, more than 80% of the processing tomatoes are grown by this method. Seeding of 3–5 seeds in a clump at 25–30cm ensures 2–3 plants/clump. Seeds should be sown 1.25 to 2.5mm deep. After establishment of plants, thinning should be done to maintain 1–2 seedlings/hill.

Planting

In northern plains, generally autumn and spring summer crops are taken. However, in southern parts, 3 crops are taken which are sown during June–July, October–November and January–February. In Punjab, only spring summer crop is taken due to heavy incidence of tomato leaf-curl virus in autumn. Higher yield is obtained due to more plants/unit area. However, with closer spacing, quality of fruits is reduced due to more incidence of diseases and pests. The recommended spacing is 60m × 45cm or 90cm × 30cm. Flat bed and raised bed methods are used. Raised beds economize watering, there is less incidence of diseases and pests and sometimes has the advantage of staking. Mechanically harvested and processing tomatoes should be planted at close spacing. Hybrids are planted at wider spacing from row-to-row and close spacing of plant-to-plant to facilitate mechanization.

Training and pruning

Training helps in better utilization of light and air. The fruits are trained under leaves to protect them from sun scald. For outdoor crop, where there is a limited area, stakes are used for training. Training, pruning or pinching are required to produce quality fruits. In indeterminate tomatoes, training increases number of fruits and maintains uniform size of fruits, increasing total yield and quality of fruits. Training is done with the support of wire, string and stakes in glasshouse or greenhouse. In field crop, training is done with the support of bamboo sticks and wire or rope. If there is excessive growth, pinching or pruning of side shoots improves size and uniformity of fruits. Methyl ester of long chain acids and alcohol suppress the side shoot formation. Infra-red light and kinetin also suppress the side shoot formation. Pinching of the main shoot at the top improves the size of terminal fruits. This is done in indeterminate varieties when plants attain the maximum height. To reduce the incidence of diseases, mature old leaves should be removed. However, during summer season, foliage should not be removed to protect fruits from sunscald.

Both macro and micronutrients are required judiciously for economic yields of tomato. Application of N, P, K and B is essential. However, their quantity depends upon the availability of these nutrients in the soil. The NPK 120:60:50kg/ha should be used. However, for hybrids, higher quantity of N is applied. A high level of N at seedling stage and moderate level at flowering and fruiting stage is required. However, high level of N in plant reduces the C/N ratio resulting in unfruitfulness. The application of P improves root development, whereas K promotes colour of fruits. Higher level of K improves the response of high levels of N for growth and yield. Calcium ammonium nitrate and diammonium phosphate and superphosphate are better sources of N and P. For better utilization of N, split application and band placement are ideal. Foliar application of urea (0.4–0.6%) is very effective. A starter solution of 20g of 12:24:12 N, P and K in 10 litres of water should be applied with irrigation at transplanting.

For raising a healthy crop, application of green manure, farmyard manure, sludge, neem cake and biofertilizer, is beneficial. Boron and zn are important micronutrients required for tomato cultivation. Boron is applied in the form of borax @ 20–25kg/ha as soil application. Spraying of 0.22–0.4% borax at fruit formation stage helps fruit development. Borax improves shape, size and colour of fruits. Thus every farmer should compulsorily apply borax. In Zn deficiency, zinc sulphate should be applied @ 25kg/ha in the soil.

Aftercare

Weeding, hoeing, earthing-up and mulching, are very important. About 2–3 hoeings are essential at the initial stage of plant growth. The soil should be kept loose for better growth of plants. Two earthing-up are sufficient for optimum growth. Although manual weeding is mostly followed, several chemicals are quite effective to control weeds. Application of Pendimethalin @ 1kg ai/ha + 1 hand-weeding 45 days after transplanting, or Sencor @ 2.5kg ai/ha or gol @ 0.25kg ai/ha applied 2–3 days after transplanting are effective to control weeds. Since 40–45 days after transplanting is the most critical stage of crop weed competition in tomato, weeding at this stage is quite essential. Weeds may also be controlled with the application of mulches. Straw, saw-dust and black polythene are used for controlling weeds. They also help conserve moisture and reduce incidence of insect pests and diseases.

Irrigation

Frequent irrigation is essential for optimum plant growth, fruiting and yield. The crop should be irrigated at 8–12 days interval. However, in summer, more frequent irrigation is required due to higher surface evaporation. Generally open-furrow method of irrigation is followed. Nowadays, trickle and drip method of irrigation are practised. Drip system is highly economical and produces quality tomatoes. The drip system has been modified which provides irrigation with fertilizer. This method is being used in greenhouses, glasshouses or plastic houses.

Seed production

Seed is an important input in tomato production. To produce genetically pure ,high quality seed, isolation distance of 50–200m between 2 varieties is essential. The production technology of the seed crop is almost the same as that for the fresh market. Inspection of tomato crop before flowering, at flowering and fruiting, and at fruit maturity and ripening should be done. In northern plains, good quality seed can be obtained from tomatoes harvested from December to March. Seed obtained from tomatoes produced in summer, is poor in germination.

For extraction of seeds, fermentation method, alkali treatment method and acid treatment method are recommended. In fermentation method, the ripe tomatoes are crushed by hand or mechanically. They are kept for fermentation for 2–4 days at 15°–24°C. Fermentation at high temperature reduces the germination of seeds. After fermentation, the debris on the top is removed and seeds settled down at the bottom of the container. All the liquid is removed and seeds are washed and dried in partial shade or drier.

In alkali treatment, the seed slurry is mixed with 10% washing soda with equal volume and kept overnight. The next day, all the seeds settle down at the bottom of the container. The liquid is decanted off and seeds are washed with tap water. This is the safest and best method of seed extraction. In acid fermentation, 250ml of commercial hydrochloric acid is thoroughly mixed with 10 litres of slurry and left for 30 minutes. The pulp is stirred and seeds are washed with water, dried in sun or drier. Seeds can be extracted with concentrated hydrochloride acid @ 20ml/kg for 30 minutes. The extracted seeds are treated with 2–4% trisodium orthophosphate for 15–30 minutes to inhibit viruses. Seeds should be stored in air tight aluminium foil bag at cool temperature.

   
Harvesting & Postharvest management

Tomatoes are harvested at several stages—mature green, turning pink, red ripe and over ripe. The stage of harvesting depends upon the purpose for which the tomatoes are harvested. Generally, tomatoes are harvested at mature green to turning stage for distant marketing. For fresh consumption, pink to light red tomatoes are preferred. For seed production, red ripe tomatoes are ideal. After harvesting, tomatoes are cooled rapidly at 13°C, which increases their shelf-life. Tomatoes are then graded into A, B and C grades by machine or hand.

Tomato yields around 250q/ha. However, hybrids with staking produce more than 400 q/ha.

Tomatoes ripen on plant itself. However, ripening may take place after harvesting also. For artificial ripening, tomatoes are harvested at mature green stage or at turning stage and kept under room temperature (15°–25°C). Then ripening takes place with the evolution of endogenous ethylene. There is some weight loss with artificial ripening but this is negligible. The artificial ripening is required when there is very low or high temperature. To enhance the ripening on plants, Ethrel @ 1,000–2,000ml/litre should be sprayed at the start of ripening. Application of Ethrel at immature stage of fruits causes injury to the fruits and plants.

The harvested tomatoes produce adequate quantity of ethylene which is sufficient for their ripening. If tomatoes are kept in an air-tight place and ventilation is not allowed, there is no need to apply Ethephon for their ripening. However, Ethephon can be sprayed on plants to harvest early crop.

For distant transportation, wooden boxes, crates, polythene bags or baskets, are used for packing tomatoes. The cardboard boxes, are ideal for packing. Polythene packing causes slow ripening, reduces weight loss and increases shelf-life of tomatoes.

High temperature, humidity and oxygen pressure increase the spoilage of tomatoes, reducing their shelf-life. High CO 2 and low O 2 increase the shelf-life of tomatoes. CO 2 (5%) and O 2 (2.5%) are best atmospheric storage conditions.

   
Physiological Disorders

There are a number of disorders caused by adverse environmental conditions during growth and development, storage and marketing. Fruit cracking, blotchy ripening, puffiness, cat facing and sun-scald are important ones.

Cracking of tomatoes is very common. Four types of cracking—radial, concentric, burst and cuticular—are found. Concentric and radial are very severe, and are mainly due to the effect of soil moisture, rain, dew and plant vigour. When rain follows, a long dry spell there is cracking. High day temperatures followed by low temperatures with high relative humidity also cause fruit cracking. In calcareous soil, deficiency of B causes cracking. Soil application of borax @ 15–20kg/ha or spraying of borax (0.25%), 2–3 times at fruiting stage to ripening reduces fruit cracking. There should be proper control of moisture, especially at fruit maturity and ripening stages. Thick foliage, and pericarp of fruits are associated with less cracking.

Greenish-yellow to whitish patch on tomato, mostly on stem-end portion of the fruits, is called blotchy ripening. Caused mainly by K deficiency, it occurs due to imbalance of N and K. High level of N, Ca and Na are associated with blotchy ripening. To control blotchy ripening, potassic fertilizer should be applied adequately and temperature should be controlled. Short photoperiod and relatively low day temperature reduce its incidence.

In puffiness, fruit surface is generally flattened and locules are unfilled with pulp and seed. The affected fruits become light in weight and more or less hollow. The outer wall (pericarp) shows normal growth but remaining internal tissue especially parenchymatous tissue are retarded in growth, resulting in light weight and partially filled tomatoes. Puffiness is associated with poor pollination, and abortion of ovules due to adverse environmental conditions particularly high and low temperature. To reduce its incidence, maintenance of normal temperature, frequent irrigation, spraying of boric acid (10–15ppm) and some growth regulators is required.

At low temperatures, generally, ridges, furrow, blotches at the blossom-end are observed. Thus, there is multilocular formation and fruits become mis-shaped. This is due to faulty pollination at low temperatures. There is imbalance in the endogenous growth regulators due to faulty pollination, fertilization and seed development. This problem is more in the tropical and subtropical tomatoes grown in winter. However, varieties developed in temperate countries and grown in India have less such problems. Application of auxins especially parachlorophenoxy acetic acid and regulating the temperature and date of planting may reduce this disorder.

Sun-scald and low temperature injury are general problems of tomato in summer and winter respectively in northern India. On exposure of tomatoes to high temperature (40°C and above) and high sunlight, whitish, greyish, sunken and papery lesions develop. These lesions may have secondary infection of fungus which show black dark spots, making tomatoes unfit for consumption. Varieties having sparse foliage, thin pericarp and immature size are more prone to this. At low temperature also, tomatoes are frosted and injured showing whitish-yellow, sunken symptoms. Dense foliage varieties with thick pericarp developed in temperate countries are less prone to low temperature injury.

Blossom-end rot is a severe physiological disorder. It is caused by calcium deficiency in the greenhouses. In India, the incidence is not noticed in outdoor tomatoes. However, if there is an incidence of this disorder, calcium sulphate, calcium hydroxide and calcium chloride should be applied. 

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Chromosome Number: 20
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Capparales
Family
:
Brassicaceae
Genus
:
Brassica
 
Turnip is grown in temperate, subtropical and tropical regions of India. It is extensively cultivated in Bihar, Haryana, Himachal Pradesh, Punjab and Tamil Nadu.
   
Climate and soil  

Cool and moist climate is most favourable for growing turnip. However, it can also be grown where summers are mild. The roots develop best flavour, texture, and size at a temperature of 10°–15°C. The short day length and cool weather favour proper development of roots. The long day and high temperature induce early bolting even without adequate development of roots. In hot weather, roots become fibrous, tough and more pungent. The Asiatic types can tolerate high temperature, while temperate types are quick-growing and flourish well under cool weather.

Turnip can be grown in all kinds of soils but it grows well in loam soil having sufficient humus. The well-drained, sandy loam soil is ideal for its cultivation. The extremely light sandy soil or too heavy soils should be avoided. As in such soils either the plant growth is hampered or forked and defective roots are formed which are unfit for market.

 
Varieties

Turnip varieties are divided into 2 groups—Asiatic or tropical types and European or temperate. These can further be classified on the basis of root shape as well as skin and flesh colour. The varieties recommended for cultivation are:

Early Milan Red Top

Its roots are deep flat with purplish-red top and white underneath. The flesh is pure white, well-grained, crisp and mildly pungent. The top is very small with 4–6 sessile leaves. It is an extra early and very high-yielding variety.

Golden Ball

Its roots are perfectly globe-shaped, medium-sized and smooth. It has bright, creamy-yellow skin and pale-amber coloured flesh of fine texture and flavour. The top is small, erect with cut leaves.

Punjab Safed 4

An early-maturing variety, commonly grown in Punjab and Haryana. The roots are pure white, round, medium-sized with mild taste.

Purple Top White Globe

It is a heavy-yielder and large-rooted variety. The roots are nearly round, upper part purplish, lower portion is creamy. The flesh is white, firm, crisp and mildly sweet flavoured. Top is small, erect with cut leaves. It is suitable for growing during cooler months.

Pusa Chandrima

Its roots are medium to large, nearly flattened globe to globular, smooth, pure white skin with fine grains. The flesh is sweet and tender. Top medium and leaves not so deeply cut. It is an early-maturing (50–60 days), heavy cropper with an average yield of 400q/ha. It is suitable for sowing from October to December in plains.

Pusa Kanchan

It is a selection from the cross of Asiatic (Local Red Round) and European (Golden Ball) varieties. It contains good qualities of both the parents. The roots look just like the Local Red Round. The skin is red, flesh is creamy-yellow with excellent flavour and taste. The leaf top is shorter than the Local Red Round. It becomes ready for harvesting in about 10 days later than the local parent. Its roots can be kept for a longer time than Local Red Round in field without becoming spongy.

Pusa Swarnima

The roots are flattish round with creamy-yellow skin and pale-amber coloured flesh of fine texture and flavour. Its top is medium, leaf blade is not so deeply cut. It is suitable for growing from June to October in hills and October to December in plains. It matures in 65–70 days.

Pusa Sweti

Attractive, white roots of Pusa Sweti mature 45–50 days after sowing. A very early-maturing variety, it is suited for October sowing in plains.

Snow Ball

This variety is an early temperate type with medium-sized small top. Its leaves are erect, cut and medium green. The roots are round, smooth with pure white skin. The flesh is white, fine-grained, sweet and tender.

   
Cultivation  

The method of land preparation for turnip is the same as for radish. Asiatic turnips are sown from July to September, whereas European types from October–December in northern plains of India. In hills, sowing time is usually from July–September. Its seeds are sown directly either in lines or on ridges. Normally, flat beds are used for sowing turnip but sowing in low lying area or during the rainy season should be done on ridges. Seeds are sown on ridges or rows 30cm apart while a spacing of 5–7cm is kept within the row. The seeds are sown 1.5cm deep. Seeds can be mixed with sand or ash to facilitate uniform sowing. Generally thinning is done 10–15 days after germination. The plants are spaced 10–15cm apart within rows. Bold seeds germinate better than the medium ones. About 90–95% seeds germinate. Seeds remain viable for 4–5 years under good storage conditions. Seeds take 4–6 days to germinate.

Manuring and fertilization

The quantity of manures and fertilizers to be applied depends upon climate, fertility status, pH level and texture of the soil. The proper time of application is equally important to facilitate optimum intake of plant nutrients for good harvest. Different doses of NPK have been recommended for various agroclimatic zones of India. However, a basal dose of 20–25 tonnes/ha of farmyard manure should be applied at the time of land preparation. This is supplemented by applying 70–100kg of N and 50kg/ha each of P and K. The complete dose of P, K and half of N should by applied before sowing. Phosphatic and potassic fertilizers are applied 7–8cm deep before sowing. The remaining half of N is given in 2 split doses: first at the time of root formation and the second during development of root knobs.

Micronutrient requirement is almost similar to that of radish. Intake of B, Ca and Mo is more in turnip. Therefore, deficiency of these micronutrients is overcome by spraying 1kg/ha of Micnelf MS-24 one or two times depending upon the requirement. It helps control hollow-stem, pith formation and brown heart in turnip.

Irrigation

Irrigation requirement of turnip is similar to that of radish. This is generally irrigated at 8–15 days interval depending upon weather conditions. The increase in moisture stress drastically affects its yield. Therefore, optimum required moisture is maintained by irrigating the crop at proper time.

Interculture

About 2–3 hoeings are done to keep the crop weed-free and to conserve moisture. The earthing-up is done during second and third hoeings after top dressing of nitrogenous fertilizers to produce better quality roots. Usually 2–3 weedings are done till the crop is harvested. However, at the latter stage of crop growth, the fully developed leaves also restrict the weeds. The pre-emergence application of herbicide, Tok E-25 (Nitrofen) @ 2kg/ha effectively controls the weeds.

Seed production

The method of raising seed crop as well as the techniques of seed production are the same as for radish. The Asiatic turnips produce seed in plains, whereas European ones in hills only. The selected roots are used to prepare the stecklings by pruning the root tip from the base and leave one-third of crown after trimming off the top. These stecklings are transplanted 60cm × 60cm apart in the hills and 45cm × 35cm apart in the plains. An isolation distance of 1,000–1,600m should be kept from Chinese cabbage, mustard and other turnips to avoid contamination by crossing, with these crops. Application of 84kg of N, 50kg/ha each of P and K results into good seed yield in turnip. When 70% of the pods turn light yellow, they should be harvested immediately to avoid shattering and damage by birds. On an average, seed yield of 5–6q/ha is obtained.

   
Harvesting & Postharvest management

The fully developed tender roots of turnip are uprooted on attaining the marketable size. Normally the roots are harvested when they are 5–10cm in diameter depending upon the variety. The roots become tough and fibrous if harvesting is delayed. The harvesting should be done in the evening. The yield of turnip varies with varieties as well as growing season. On an average it yields 200–400q/ha.

Its harvested roots along with the green tops are properly washed to remove the adhered soil. The side roots are trimmed off. These are sent to the market in baskets either along with green tops or after cutting them off near the surface of the crown. The part of the foliage when bunched for market is removed by stripping off old and diseased leaves. The roots are sorted into different grades according to colour, shape, and size to give an attractive appearance in the market. Then these are immediately transported to the market and disposed off. The roots can be stored safely for 2–3 days under cool and moist conditions. However, it can be stored for 8–16 weeks at 00C with 90–95% relative humidity.

   
Physiological Disorders
Whip tail is caused due to deficiency of Mo. This is more common in acidic soils. Young leaves become narrow, cupped, showing chlorotic mottling especially around the margin, develop deep patches which ultimately affect the root growth. The affected plants are removed from the field during thinning. Further appearance of this disorder can be controlled by liming the soil and bringing the pH to 6.5. However, it is controlled by the application of 1.2kg/ha of sodium or ammonium molybdate.
Nutritional Value
 
 
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