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Sapota or sapodilla, popularly known as chiku, is an important fruit. Native to tropical America especially from south Mexico or central America, this species is mainly grown for its chickle, "the gutta parcha" extracted from its latex from stems. It is used as a base material in chewing gum and in some other industrial uses. However, in India it is cultivated for its delicious sweet fruits. The fruit is fleshy berry, variable in shape, size and weight (75–150g). The skin is thin, rusty brown somewhat scurfy looking like Irish potato, and the pulp soft, melting, crumbling with a sandy or granular texture with 1–5 hard, black seeds. The fruit is a good source of digestible sugar (12–18%) and an appreciable source of protein, fat, fibre and minerals, Ca, P and Fe. It has become most popular fruit crop in Gujarat, Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh and Kerala.
   
Climate and soil  
Sapota, a crop of tropical region, needs warm (10°–38°C) and humid (70% relative humidity) climate where it flowers and fruits throughout the year. However, if taken to subtropics or higher elevation like in Punjab and Haryana, it gives only one crop from summer flowering in April and May. Under moisture-stress also, it produces one crop only.
 
Varieties
There are about 41 varieties spread all over the country. However, commercially sapota industry is based on a few varieties and in some areas it is only monoculture like Kalipatti in Gujarat and Maharashtra.
   
Propagation

Sapota is propagated through seed, which has been the basis of its variability in India. But inarching using rayan as rootstock, air-layering and softwood cuttings, using IBA (2,000ppm) treatment are successful methods of propagation. However, plants raised through air-layering or cuttings establish poorly and are vulnerable to wind damage. However in west-coast, air-layering is common and such plants perform better in shallow soils. For air-layering, 1–2 years old 45–60cm long juvenile matures shoots of pencil thickness with plenty of healthy dark green leaves are selected. On the base of such shoots a ring of bark (2.5–3cm wide) is removed on which IBA + NAA (10,000ppm) each in lanolin paste is applied, covered with rooting media like sphagnum moss, vermiculite or garden soil and wrapped with plastic. In 3 months, roots emerge, then layers are slowly separated and establish in nursery. They are planted in the next season.

Sapota on rayan is the best in respect of plant vigour, productivity and longevity. Propagation of sapota by inarching using rayan as rootstock is the most accepted method of its commercial cultivation. Two years old potted rayan plants with pencil thickness are utilized and grafting is done in December–January. The plants are ready for separation in June–July of following year. This method is tedious, cumbersome and time-consuming. Softwood grating using rayan as rootstock gives 93% success in-situ. It is an economically viable, faster, efficient and best technique. July–August is ideal time for it. Since detached scion is used in this method, it is possible to store scion sticks in banana sheath to help exchange of plant material.

   
Cultivation  

Planting

Since sapota is a crop of warm and humid tropics, it can be planted in any season provided irrigation facilities are available. But it is beneficial to plant the grafts in beginning of the rainy season. In areas having heavy rainfall, it can be planted in September. In light soils, pits of 60cm × 60cm × 60cm size, whereas in heavy and gravely soils pits of 100cm × 100cm × 100cm size are made in April–May and exposed to sun for 15 days. Top 30cm soil is mixed with equal quantity of well-rotten compost or farmyard manure, 3kg superphosphate and 1.5kg muriate of potash are used for pit filling. To begin with all sides and bottom of the pit are dusted with 5% BHC dust and pits mixture is added to fill the pit and remaining vacant space is filled with remaining soil to a height of 15cm above soil surface. Such pits are left to monsoon rains for settling and then planting is done at appropriate time. At the time of planting, a small hole sufficient to accommodate the ball of soil and roots of grafts is made in the centre of the pit and planted with scion in the direction of heavy wind to avoid damage to joint. After planting, soil around the plant is gently and firmly pressed and stakes are provided to avoid wind damage. Planting should preferably be done in the evening to avoid sun heat. The plants are then lightly watered. Young plants should also be protected against sun scold by providing dry grass thatch on top and three sides excepting the south-east for sunlight. Such well-cared plants establish fast.

Since sapota tree makes uniform all-round growth, square system of planting is recommended. However, in land with 5–15% slope, contour planting is recommended. Depending on growth habit, sapota orchards are planted at 10m × 10m but being slower in growth, it takes longer period to occupy allotted space. Therefore, high-density plantations having 5m × 5m spacing up to the age of 13 years are very remunerative. Thereafter yields begin to decline.

Training and pruning

A seedling tree grows excellently giving a shape of an umbrella. However, plants raised through inarching require training for appropriate shape and framework development. No definite system of training has been developed for sapota. Most trees are trained in central leader system.

Sapota being an evergreen tree requires no regular pruning but regulation of vegetative growth to improve productivity and quality of fruits is necessary. At times thinning of branches is affected in old plantation. Pruning in sapota is confined to open the tree to light, and removal of dead and diseased branches.

Manuring and fertilization

Owing to evergreen nature of the plant, any inadequacy in its nutrition leads to sub-optimal yield. Deficiency of N leads to yellowing of leaves from margin to mid-rib. The P-deficient plants have purplish flecks on lamina with rusty pigmentation all over and inadequacy of K is marked by development of chlorotic symptoms along leaf margins which become dark grey in advanced stage. Zinc deficiency is marked by small and erect leaves, short internodes and defoliation of terminals, whereas in calcareous soils Fe deficiency causes general yellowing of leaves with premature shedding.

A dose of 50kg farmyard manure, 1,000g N, 500g P 2 O 5 and 500g K 2 O/tree/year is optimum. This quantity can be regulated on the basis of age of tree and status of nutrients in soil especially of P and K. Under rainfed conditions, dose of N should be raised to 1.5kg/tree. Castor cake is beneficial for high-quality fruits.

Under rainfed condition, fertilizers should be applied before the onset of monsoon. However, under irrigated conditions it should be applied in 2 splits. Total quantity of organic manure and half of chemical fertilizers should be applied at the beginning of monsoon and remaining half in the post-monsoon period (September–October). Since 90% of active roots are distributed within drip up to a depth of 30cm, nutrients should be applied under tree canopy and mixed thoroughly in soil up to a depth of 15cm. In Zn and Fe deficiency, the requirement should be met through application of organic manures and spraying of ZnSO 4 and FeSO 4 (0.5%).

Aftercare

Depending on growth habit of sapota tree a planting distance of 10m × 10m is ideal. Being a slow-grower, it takes longer to occupy allotted space. Therefore, intercropping is imperative. Intercropping banana, papaya, pineapple and cocoa; French bean, tomato, brinjal, cabbage, cauliflower and cucurbits is recommended depending on climate and water resources. In established orchards, pre-monsoon and post-monsoon intercultivation is recommended for better aeration and effective weed control. In young orchards, weed hazard is common. Use of 2kg Bromacil + 2kg Diuron/ha as pre-emergence spray is effective for a period of 10–12 months. Mixed plantation with mango and guava should be avoided to reduce the problem of fruitfly.

Irrigation

Habit of tree and its vegetative growth demand continuous supply of water. But sapota is grown both under irrigated and non-irrigated conditions. Sapota requires irrigation at 30 days interval in winter and 15 days in summer. Adoption of drip irrigation system is also beneficial, saving 40% water with 70–75% higher net income. This system should be laid out with 2 drippers spaced 50cm from tree during initial 2 years and 4 drippers at 1m from tree until 5 years of age. With dripper discharge rate of 4litres/hr, the system should be operated for 4 hr during winter and 7 hr during summer on alternate days. Under short supply of water, timing could be 3hr and 30minutes in winter and 5hr and 40minutes in summer.

 

   
Harvesting & Postharvest management

Sapota takes about 7–10½ months from anthesis to maturity of fruits depending on variety and climate. Fruits follow double sigmoid pattern of growth. Properly developed fruits have high TSS and sugar, and reduced acidity, astringency, latex and vitamin C. Maturity is decided on the basis of ease with which brown scruff gets off the fruit surface and development of yellowish tinge intermixed with corky-brown colour on the surface of the fruit. At this stage, practically no green tissue and milky latex are seen on fruits when scratched with nails. The fruits are hand picked or harvested with special harvester which has a round ring with a net bag fixed onto a long bamboo. Depending on management level, 15–20 tonnes fruits are harvested from a hectare.

Since sapota is a climacteric fruit, it has to be ripen artificially. Fruits are highly perishable and they undergo rapid ripening changes within 5–7 days during which the fruits become soft, sweet and develop excellent aroma with decline in tannins, latex sapotin, aldehydes and acidity. These changes are associated with increase in production of ethylene, rate of respiration, catalase, peroxidase and PME activities. These changes can be regulated through chemicals, temperature and storage gas composition.

Harvested fruits should be cleaned of latex and scurf by washing in clean water to make them look attractive. Such fruits should be graded into big, medium and small sizes. Fruits should be tightly packed in cardboard boxes of 10kg capacity with rice straw as padding material and with ethylene absorbents and transported quickly to wholesale markets. For extending shelf-life and to avoid storage rots, fruits can be dipped in GA 300ppm + Bavistin 1,000ppm solution at prepacking stage. For uniform and rapid ripening Ethephon (1,000ppm) can be utilized at 20°–25°C. Modified storage with 5–10% (c/c) CO 2 can be employed for long storage (21–25 days). Refrigerated vans (12–13°C) should be utilized for long distance and export markets.

   
Physiological Disorders

Wilt or die-back is common where sapota cultivation is being extended to traditionally rice-growing regions. Due to anaerobic conditions in monsoon and post-monsoon season in such areas wilt is of common appearance aggravated by Fusarium spp. This can be controlled by effectuve drainage facility before planting.

The shape of fruit is related with number of seeds in it which depend on conditions for pollination at anthesis. High temperature and rainfall during flowering cause oblongation of fruits. Therefore, cultivation of sapota in areas with extreme summer temperature should be avoided.

Sometimes fruits do not develop into their normal shape but develop a depression or furrow towards the calix-end. This symptom usually appears immediately after heavy rainfall and is aggravated by high intensity of irrigation. Therefore over-irrigation should be avoided.

The fruits exposed to intense sunlight do not ripen uniformly, developing corkiness during winter. This is probably due to killing of hydrolysing enzymes by alternating moisture accumulation and heating of fruit surface in winter. Thus its trees need to grow vigorously.

Nutritional Value
 
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Chromosome Number: 22
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Gentianales
Family
:
Apocynaceae
Genus
:
Rauvolfia
 

Sarpagandha is a perennial, native Indian herb. Its roots are used for controlling high blood pressure and certain forms of insanity in Ayurvedic system of medicine since ancient times. It has received worldwide recognition after isolation of its bioactive reserpine alkaloid in allopathic medicines. In addition, its sedative property is utilized by Ayurvedic physicians in treatment of insomnia, epilepsy and asthama. It is cultivated commercially in Madhya Pradesh, Uttar Pradesh, West Bengal, Assam and Orissa. The root is its economic part, containing 55 alkaloids, of which reserpine, deserpidine, ajmalicine, serpentine and yohimbine being pharmacologically active and important. The commercial root crop contains 1.4–3.0% of total alkaloids depending upon age, locality and drying of roots. Of these, ajmalicine, reserpine and serpentine content are highly potent in medicine.

Sarpagandha is an erect, sparsely branched, evergreen herb of humid tropics, attaining 0.75–1.0m height under cultivation. It gives out 2–6 branches from lower part of the stem, bearing simple, shortly-stalked, leathery, elliptic-lanceolate leaves, arranged 3–5 in a whorl. Flowers are borne in both terminal and axillary compact cymes. It is 1.2–2.5cm long with dark pink thalamus rendering it an attractive appearance. It has white, long tubular corolla. Fruit is a drupe, ovoid in shape, purplish black at maturity containing ovoid, hard seeds. The root is tuberous, 40–60cm deep, branched, with corky bark, having irregular longitudinal fissures. The bark, very bitter in taste, has most of its alkaloids.

The crop grows luxuriantly in deep, loamy to clay-loam soils rich in organic matter and of 6.0–8.5 pH. Although, it prefers high rainfall, it can be cultivated profitably in lateritic and black cotton soils in low rainfall tract with irrigation. Waterlogged lands and frosty conditions should be avoided. The temperature varying from 10°–38°C is ideal. It sheds leaves during winter in north India. R.S.I.is a popular variety in Madhya Pradesh, producing good root yield. It is a long-duration crop, remaining in the field for 18–20 months.

Its commercial cultivation is done mainly through seed. A nursery of 500m prepared under partial shade produces enough seedlings to plant one ha crop. For such nursery, 6kg seed is enough. Seeds soaked in water for 24hr, air dried, treated with Thiram (3g/kg) are sown in furrows 2–3cm deep, 20cm apart in April–May. These lines are covered with soil and farmyard manure. The beds are kept moist and free of weeds. The seeds germinate 40 days after sowing and 3–4 months old seedlings are transplanted in field. The land is prepared to a fine tilth. Add 20–45q/ha of farmyard manure together with 20kg of Aldrin (10%) at land preparation. In general, 20, 40 and 40 kg/ha of N, P and K are given basally, whereas 20kg of N is drilled in rows 75 days after sowing and again in the next rainy season.

It has a deep root system which allows it to resist a long period of drought. But 5cm deep irrigation during drier season at 20–30 days interval promots maximum root yield. Thus the crop is given 15–16 irrigations and 5–6 weeding-cum-hoeings. Soybean or onion in kharif and garlic in rabi are better intercrops during first year.

The roots are dug out in autumn (November–February) during second year and both tap root and its lateral branches besides attached fibrous roots are collected. These are washed and dried in the sun. Since its fibrous roots are rich in alkaloids, they should not be left out. It loses 60% of its weight on drying due to loss of moisture. An average yield of 1.6–2.0 tonnes/ha of dry root is obtained. The roots are cut into 12–15cm pieces for convenience of drying and storage. It can be stored for 2–3 years in godown without loss in potency.

   
 
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Chromosome Number: 28
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Rosales
Family
:
Rosaceae
Genus
:
Rosa
 

Scented rose or damask rose ( Rosa × damascena ) is grown in India for its pleasant, sweet smelling, large, pink to red flowers used for making rose water and attar. It is grown in 3,000–4,000ha in Aligarh, Gazipur, Farrukabad (Kanauj) and Balia districts of Uttar Pradesh, besides smaller area is in Ajmer (Pushkar) and Udaipur districts in Rajasthan. It is a perennial, hardy shrub growing 2m long, with numerous stout hooked prickles intermixed with glandular bristles on its stem. Leaves are compound, imparipinnate having 5–7 leaflets, ovate to oblong in shape with serrated margins. Flowers are borne in groups of 5–7 both in axillary and terminal corymb in varying shade of pink colour. The flowering is restricted to spring season for 3–4 weeks in a year. The aroma is due to essential oil secreted in papillae of epidermal cells (petals) and is given off as soon as formed. Half open flowers have more fragrance. Other species R. centifolia (Cheti gulab) and R. borbonia (Edward rose) are also grown in small acreage mainly for making rose water and gulkand .

The cultivar, Noorjehan, produces high yield of flowers (2 tonnes/ha) and is grown in Gangetic plains. Jawala is recommended for cultivation in subtropical regions in foothills. Another cultivar, Himroz, is suitable for temperate region (1,200–2,500m). It also produces higher flower yield. Recently rose cultivation is catching up in Kangra district of Himachal Pradesh.

Rose is grown in Gangetic plains over well-drained alluvial soils of 8–8.5pH. However, the crop needs fertile, slightly acidic soils with high organic matter in temperate region with open sun for higher flower yield. A plantation is raised from simi-hard, woody stem-cuttings (25–25cm long), planted in nursery . It takes 3 months for initiating rooting. Use of IBA (200ppm) over cut ends induces early rooting. A nursery area of 20m × 5m is needed to produce 10,000 rooted plants to plant a hectare crop, planted at 1m × 1m spacing.

During October–December, 1m deep and 0.5m wide furrows are made in well-prepared fields. The soil is mixed with 2.5–3 tonnes/ha of farmyard manure and 20kg each of P and K is given at 3–5cm depth. Thereafter, rooted stems are planted in pits. A plantation needs 10–12 irrigations in a year and up to 200kg/ha of N is given in 2 equal splits during October and January. Sometimes micronutrients are in short supply in the soil and a mixture of these nutrients (available under different trade names) is given to the land which improves flowering. Pruning is done of 2-year-old bushes in later part of December anually at a height of 50cm over the ground level. The bushes take 70–90 days after pruning to bear flowers.

Rose bushes commence blooming in March of the second year after planting but commercial yield is obtained from third year onwards and continues till 12–15 years. Flowers are hand-picked when they begin to open in early morning hours before the sun rise. These should be distilled immediately but never later than 24hr. Where storage of flowers becomes necessary, sprinkle a weak common salt solution in water to check fermentation and evaporation of the oil. The fresh flowers are distilled in hydro-distillation or steam-distillation units. The hydro-distillation is an age-old procedure where 100-litre capacity copper stills are used and given slow but constant heating. It takes 4.5–5hr to give an yield of 0.25% in commercial units. Co-habitation of water is advised to be cycled through filling in the still to recover water-soluble aroma compounds of the oil. Steam distilleries use large steel vessels and may produce an yield up to 0.4% oil content. Solvent extraction is also carried (mainly in France) to obtain high yield of its concrete. The fresh rose oil has delicate sweet scent, containing 34% l-citronellol, 35% geraniol and 12–13% nerol besides a large number of minor aroma compounds. 

Vetiver or khus (Vetiveria zizanioides) is a tall, perennial grass which grows wild in drier, periodically flood inundated tracts, of western and north-central India. It produces spongy, much branched, root system (khus roots) with fine rootlets, containing a fragrant oil which is a perfume by itself. The dry aromatic roots are also used to make curtains, mats, fans and other fancy goods as the proudct emits a sweet cooling aroma for a long period when moistened. The oil is used as a valuable fixative in blending of perfumes, cosmetics and scenting of soaps. Its cultivation is largely scattered over small holdings in Kerala, Karnataka, Tamil Nadu and Andhra Pradesh and to a lesser extent in Uttar Pradesh. Considering the high quality of oil produced in India compared to Indonesia, Brazil and Haiti, the north Indian type vetiver oil has a good potential for export.

Khus occurs wild in wet and damp environment, common over marshy lands in south-east Rajasthan, Haryana and north-central Uttar Pradesh up to 1,200m elevation in the Himalayan foothills. It produces long, narrow leaves (75cm × 0.8cm) from a small stout rhizomatous tuft, having glabrous joints and scrabid margin. The inflorescence is long, narrow, panicle (15–40cm) bearing numerous racemes, in whorl, in central axis. Each spike has 2 florets, one is sessile and bisexual while other is stalked and staminate. The plants profusely bloom in north India and set viable seeds. But its commercial plantation is raised only from rooted slips to maintain genetic purity and quality of the oil. It is a unique xerophyte, which survives under seasonal flooding, endures long periods of drought and tolerates a fair degree of soil salinity and high atmospheric temperature. It has good soil binding property and can stabilize eroded slopes and bunds. The roots can travel long distances in light sandy soils to get moisture.

Two genotypes of vetiver are found in India. The first group is called as north Indian type, represented by Bharatpur bird sanctuary material (Rajasthan). It has thick stem, narrow leaves, profusely flowering with medium-growing and highly fragrant roots but has low oil content (0.2–0.8%). The oil is laevorotatory. The other one is represented by material grown in Kerala and Karnataka. This genotype grows all over south Asia and Latin America. It has broader leaves, bushy growth, biennial flowering and high pollen sterility. Its roots are more branched, and produce higher oil content (0.6–1.2%). Its oil is dextrorotatory in nature. Two commercial varieties have been developed in India. They are Hybrid 8 and Sugandha. These yield 14–18kg of oil with high vetiverol content (70–85%). In south India, variety Nilambore is popular from Karnataka genepool. It produces high oil content (20kg oil/ha). The oil is dextrorotatory in nature.

Vetiver prefers sandy loam soils (6–8 pH) in warm and damp weather conditions. It grows luxuriantly over higher rainfall tracts of Kerala and Western Ghats region. The growth ceases in winter season in north India. A medium fertile soil is ideal. Clayey soils, where root growth is poor, should be avoided for its cultivation.

The land is deeply ploughed by cross harrowing. It is kept open for weathering to hot sun for 10–15 days. Thereafter, it is levelled and laid out into beds. The farmyard manure @ 10 tonnes/ha together with 25kg of BHC (5%), and 20, 40 and 20kg each of N, P and K fertilizers are added at land preparation. About 15–20cm long- rooted slips are separated from old root clumps. These are planted at 60cm × 25cm during July–August, maintaining a plant population of 60,000/ha. Their growth is slow in first 90 days. Therefore, intercropping with cowpea (fodder), clusterbean, blackgram and greengram is advised. The crop is given additional dose of 60kg of N as topdressing. The plants are earthed up after planting when one-third N is topdressed; the remaining N is given in early spring season. About 2–3 interculture operations are done to control weeds. A pre-emergent application of Atrazine or Oxadizone (0.5kg in 800 gallons of water) control weeds in early kharif season (where intercropping is not done). It needs 8–10 irrigations of 5cm depth in drier tracts. The plants are cut at 30cm above from the ground at the onset of autumn season to facilitate tillering, good root development and reduce incidence of leaf-blight on regrowth.

The roots are dug out at 15–16 months after planting in next autumn. If delayed, its oil content reduces. Digging is expensive operation. Use of one disc in a disc plough, which may turn soil at 30cm depth is recommended. The dug out roots are separated, cleaned and dried for 7–10 days in shade (till 10% moisture remains in them). The roots are light in weight and yellowish in colour, taking 24–36hr to exhaust all oil content when charges in steam distillation under pressure. A dark coloured heavy viscous oil is received with highly persistent fragrance. Since the oil of high boiling fractions is obtained in the later part of distillation, the distillation is continued for long time so that it is not lost. The oil can be stored in aluminium containers, filled up to the brim and remains stable for a fairly long period but storage of roots over 30 days begins to lose its oil content and a large percentage of the oil is lost in 6 month of storage. 

   
 
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Chromosome Number: 28
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Fabales
Family
:
Fabaceae
Genus
:
Cassia
 

Senna is a small, perennial, branched under-shrub.It is cultivated traditionally over 10,000ha in semi-arid lands in coastal districts of Tirunelvelli, Ramnathapuram and Madurai in Tamil Nadu. Although, successful cultivation has been demonstrated in many parts in western India, its commercial cultivation has recently come up in Kutch (Gujarat) and Jodhpur division of Rajasthan. It can grow over sand-dunes after rainy season and can be maintained as a perennial crop for 2–3 years. Since its leaves and pods are common laxatives, they are widely used in medicine and as a household remedy for constipation all over the world. India is the main producer and exporter of senna leaves, pods and sennosides concentrate to world market.

Its plants grow up to 1m tall over marginal lands in subtropical climate in peninsular India. It sheds leaves with the onset of cold weather in north-western India. The crop thrives over well-drained, sandy loam lateritic soils of 7–8.5 pH, though fertile fields and irrigated crop support better growth and produce higher yields. It needs an alround warm and dry weather. Even temporary stagnation of water in fields can cause loss to the crop. As an annual crop, it remains in field for 110–130 days. The plant bears compound leaves, made up of 5–8 pairs of shortly stalked oval-lanceolate leaflets (2.5cm × 1.5cm) and produce successive flush of flowering shoots both in axillary and sub-terminal position 60–70 days after sowing. The flowers are large and brilliant yellow in colour, producing medium-sized pods (3.5cm–6.5cm × 1.5cm) after 90 days. They contain 5–8 yellowish, flat seeds. It is predominantly self-pollinated crop but outcrossing could be high (20%) through beetles.

A composite culture called, Trinnevelly Senna, is grown all over south India. The main crop is largely rainfed, sown with monsoon rains (July in north-western India and September–October in south India), whereas February sown senna is restricted to Tamil Nadu where it is sown with spring rains as an irrigated crop. The land is ploughed, harrowed and exposed to hot sun for 10–15 days, before dividing into small fields for maintaining drainage. It is given 20:40:20kg/ha of N, P and K basally, mixed with 25kg of Aldrin (5%) or BHC (5%) to ward off cut-worms and termites. If soil is rich in K, then K2O is skipped out. Seed rate is 6kg/ha for line-sown crop, placed 1cm deep at 30cm × 30cm or 45cm × 30cm spacing in rain-soaked fields. The seeds are collected at dough mature stage, soaked in water for 12hr, treated with 2.5g/kg Captan or Thiram before sowing either wet or air-dried for 2–3hr to ensure high germination (90%). The sown crop is given light irrigation if it does not rain for next 7 days. The crop is weeded, hoed and thinned 30 days after sowing to maintain 70,000–75,000 plants/ha. The crop is given one weeding-cum-hoeing after 50 and 70 days respectively and garden soils are given 5 light irrigations during dry weather. The crop is given 40kg N/ha in 2 splits after each picking, placed 4–5cm deep in rows to ensure effective uptake.

In Tamil Nadu, senna is grown after harvesting paddy and intercropping companion sesamum, cotton and vegetables. In north-western India, senna–mustard and senna–coriander rotation gives higher returns.

Three pickings of leaves and pods are usually taken 50, 90 and 130 days after sowing. Usually, flowering shoots are chopped off initially to increase branching and to allow its plants to put up more vegetative growth. Mature leaves and 15–25 days old pods are harvested. On an average, 1.2–1.5 tonnes/ha of dry leaves and 3.5–4q pods/ha are obtained.

The dry foliage and pods should possess a minimum of 2.5 and 3.0% total sennosides respectively. The harvested produce should be spread in thin layer in open sun for 6–10hr. It is further dried in well-ventilated drying sheds for 3–5 days. It should have not more than 8.0% moisture at storage. The colour of dry leaves and pods should be ensured to remain light green to yellow. The sennosides are soluble in water and exposure of the produce to rain water during drying can reduce these contents. The produce is liable to storage loss up to 30% in content. Therefore, it is recommended to store in cool, dry place after reducing the bulk under hydraulic press and wrapped in gunny bags lined with polythene, particularly for distant transportation. Grading of the produce is common for marketing. The extra large, bold, yellowing-green leaves and pods are placed in first grade and sell at a premium.

 

   
 
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Chromosome Number: 22
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Violales
Family
:
Cucurbitaceae
Genus
:
Trichosanthes
 
Snake gourd (Trichosanthes cucumerina) is an annual, climbing vine providing both long and short fruits. India is its native home.
   
Climate and soil  
Snake gourd prefers tropical, warm, humid climate. It can be grown successfully to 1,500m above mean sea-level. It cannot tolerate frost and grows very well under 25°–30°C. Heavy rains during flowering affect its yield. A loamy soil with a pH of 6.0–7.0 is ideal for its cultivation.
 
Varieties

Some improved varieties of snake gourd are described in Table 1.

Variety

Characters

APAU Swetha

Fruits long with whitish background and green stripes. Yields 280-300q/ha in 125-130 days.

Co 1

Fruits long (160­180cm), dark green with white stripes. Yields 180 q/ha in 135 days.

Co 2

Fruits short, 30cm long, stout, pale-greenish-white with ashy bloom on their surface. Fruits being very short, this variety does not require pandal. Vines less-spreading, it can be planted closely (1.5mx 1.0m), the yield potential being 250q/ha.

MDU 1

F1 hybrid, fruits medium in length (50–60cm) with white stripes over a green background, can yield up to 350q/ha.

PKM 1

Fruits extra long (200cm), the yields being 250q/ha in 135-140 days.

   
Cultivation  

Sowing

June–July and December–January are the main sowing times. After preparing fields, add farmyard manure @ 10–15 tonnes/ha. A dose of 20–30kg N, 30–50kg P and 30–40kg K is applied basally. Pits are dug at a spacing of 2.0m × 1.5m. They are filled with farmyard manure and top soil. About 3–4 seeds are sown in each pit. If seeds are sown in polybag, 2kg seed is sufficient to plant one hectare crop. Two seedlings are planted in each hill 15–20 days after sowing in polybags.

Interculture

At 2 true leaf stage, Ethrel (250ppm) or MH (150ppm) should be sprayed and repeated 2–3 times at weekly intervals. In long-fruited varieties, vines should be trained on bower or pandal . The fruits should also be trained 4–5 days after pollination by tying a small stone at the stigmatic end of the fruits. Apply 20–30kg N/ha at flowering stage.

Irrigate the crop once a week in summer, while in rainy season irrigation is needed only if there is dry spell.

   
Harvesting & Postharvest management
Its fruits are ready for picking 70–80 days after sowing. Fully developed, tender fruits are harvested once in 5–7 days for vegetable purpose. If allowed to mature fully, fruits ripen within 2–3 days of harvesting, the average yield being 180–200q/ha.
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Chromosome Number: 48
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Lamiales
Family
:
Lamiaceae
Genus
:
Mentha
 
Spearmint is another important mint. Its oil is rich in carvone (65%) content and emits caraway like odour. The oil is useful in dentrifice, confectionery and pharmaceutical products. It bears lanceolate stalkless, light green leaves and narrow, long, terminal flowering spikes with lilac flowers, attaining a height of up to 60cm. Two commercial varieties have been evolved in India. Of them, Punjab Spearmint is an erect growing with quadrangular purple-green, hairy stem, producing 20q/ha of fresh herb. It contains 0.57% oil, the oil yield being 120 litres/ha containing 68% carvone. The other variety MSS 5 is relatively vigorous in growth, yielding 250–300q/ha of fresh herb or 150kg of oil from commercial plantations. It is cultivated in smaller area in Punjab and foothills of Uttar Pradesh. It fetches higher price.
   
 
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Chromosome Number: 12
Taxonomic Classification
Class
:
Order
:
Family
:
Genus
:
Spinacea
 
Spinach is a cool season vegetable. It is an annual crop. The rosette of leaves produced during vegetative phase is used as vegetable. Spinach is cooked with potato, onion, brinjal or alone. Leaves are rich in vitamins A (5,580IU) and C (28mg), folic acid (123mg) and minerals—iron (17.4mg), calcium (190mg) and phosphorus (42mg)/100g. Spinach is more popular in central and northern India.
   
Climate and soil  
As a cool season crop it can tolerate frost. Short day conditions coupled with moderately warm temperature are suited for its growth. Under long day and warmer conditions, bolting occurs. Under high humid conditions, leaves become more succulent and tender. Well-drained, loam soil with good fertility is best-suited for spinach, though it can be grown in a wide types of soils. Acidic soils are harmful, the optimum pH being 6–6.5.
 
Varieties
In spinach, 4 sex types exist. They are externally male, vegetative male, female and monoecius. Male plants bloom early and hence are poor yielders. Female plants give fairly high yield because they flower late and have longer vegetative phase. There are prickly-seeded varieties and smooth-seeded varieties. Similarly savoy (wrinkled), semi-savoy and smooth leaved varieties exist. Virginia Savoy and Early Smooth Leaf are improved exotic varieties. Banerjees Giant, Banarasi (Katvi palak), Khara Lucknow and Khara Palak are popular desi types.
   
Cultivation  

Propagation

It is propagated by seeds. On an average 37–45kg seed/ha is required. If proportion of male seeds are more in the seed lot, a higher seed rate is required.

Planting

Preplanting land preparation involves thorough ploughing 3–4 times, removal of stubbles and planking. Then beds are taken in convenient sizes. Seeds either broadcast or sown in lines 35cm apart and covered with a thin layer of soil. After germination, thinning is done to retain plants in 10–12cm spacing within each row.

Time of sowing depends on varieties and place of cultivation. In plains, desi types are sown during June–November, whereas exotic types from October to December. Desi types can be sown in March–May, whereas imported types in July– August in hills.

Manuring

Being a leafy vegetable, spinach requires higher doses of N for increasing leaf yield. Along with land preparation, farmyard @ 25 tonnes/ha is incorporated into soil. About 80–100kg N, 60kg P 2 O 5 and 60kg K 2 O are required. Full dose of P 2 O 5 and K 2 O and one-fourth dose of N are applied as basal dressing. Remaining quantity of N is applied in various splits (20–25kg N/ha each) after every cutting, along with weeding and hoeing.

Aftercare

Thinning of overcrowded seedlings is essential to maintain required spacing between plants. Frequent hoeing is necessary.

Irrigation

A good soil moisture is essential for proper germination of seeds. Pre-sowing irrigation is advised. Second irrigation should be given after sowing. Later irrigations depend on the season and soil conditions. Usually irrigation is done at 4–5 days intervals in summer and at 8–10 days interval in winter.

   
Harvesting & Postharvest management

First cutting can be taken about 4 weeks after sowing. It is possible to get 4–6 cuttings/season at 15–20 days interval depending on variety and season. Its yield varies from 8 to 10 tonnes/ha. Harvesting is done in the evening because leaves become crisp due to dew and easily break in the morning.

After harvesting, diseased and damaged leaves are removed and bundled into bunches of about 10–20 leaves for convenience in handling and marketing. The leaves can be stored only for about 24hr after harvesting under ambient conditions. Under cold storage (at 0°C and 90–95% relative humidity), they can be stored for 10–14 days. 

Nutritional Value
 
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Chromosome Number: 26
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Violales
Family
:
Cucurbitaceae
Genus
:
Luffa
 
Sponge gourd is a monoecious cucurbit vegetable. It is closely related to ridge gourd. Its tender fruits have smooth surface and contain vitamin A and C. Fully ripe, dried fruits having a large volume of fibrous portion are used for cleansing utensils, making shoe-soles and filters. Fibre is also used to manufacture table and bathroom mats.
   
Climate and soil  
Sponge gourd can be grown from tropical to subtropical climates. Warm humid conditions favour its cultivation. Very low temperature is deleterious and frost kills its plants. Well-drained loamy soils are ideally-suited though it can be grown on a wide variety of soils.
 
Varieties
A number of local varieties are grown. ‘Pusa Chikni’ is a high-yielding, early-maturing variety. It bears flowers 45 days after sowing. Its fruits are dark green, smooth-surfaced and cylindrical. It is suited for both spring-summer and rainy season cultivation.
   
Cultivation  

Sowing

Add 10–15 tonnes of farmyard manure and 20–30kg N, 30–40kg P and 30kg of K/ha. For rainy season crop, seeds are sown in raised beds, whereas for summer season crop seeds should be sown in pits. A spacing of 1.5–2.0m between rows and 1.0m between hills is adopted. About 4kg seed is enough for a hectare crop. About 2–3 seeds are sown in each hill.

Interculture

Irrigation is given once a week in spring-summer, whereas in rainy season only if there is a long dry spell. Spraying plants with Ethrel (250ppm) at 2–4 leaf stage can induce production of more pistillate flowers. The vines should be trained by staking sorghum straw especially during the rainy season. Summer season crop can be trained even on ground itself by spreading dry grass. Apply 20–30kg N/ha at flowering stage.

   
Harvesting & Postharvest management
Its fruits should be harvested at tender stage. If allowed to develop fully, they become spongy or fibrous which are unfit for vegetable purpose. On an average its yield is 150–200q/ha.
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Chromosome Number: 56
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Rosales
Family
:
Rosaceae
Genus
:
Fragaria
 
Strawberry is an attractive, lucious, tasty and nutritious fruit with a distinct and pleasant aroma, and delicate flavour. It has a unique place among cultivated berry fruits. Rich in vitamin C and iron, it is mainly consumed as fresh. Jam and syrup are also prepared from strawberry. It is cultivated in tropical and subtropical areas round the year. It is cultivated commercially in Himachal Pradesh, Uttar Pradesh, Maharashtra, West Bengal, Nilgiri hills, Delhi, Haryana, Punjab and Rajasthan. Owing to wide climatic and soil adaptation and high returns, it has tremendous potential in India. Its cultivation can be extended to other suitable areas having assured irrigation and transport facilities.
   
Climate and soil  

Strawberry grows well under temperate climate. Some cultivars are grown in subtropical climate also. Daylight period of 12hr or less and moderate temperatures are important for flower-bud formation. Each cultivar may have a different day length and temperature requirement. Some cultivars are adapted to septentrional culture (short days in autumn and hard winter) or to meridional conditions (long days in autumn and moderate winter). Strawberry Senga Sengana, Redgaunlet and Gorella are grown under septentrional conditions, while Tioga is an important cultivar of meridional region. It can make flower buds under longer day length. Besides, there are several day-neutral strawberries—Silva, Fern, Muir, Hecker, Tristar and Trileute—that have made their cultivation possible in different times of the year. Day-neutral strawberries are high yielders. Temperature plays a critical role in the development of strawberry at a particular place.

The strawberry can be grown on any type of soil—poor sand to heavy clay—provided proper moisture, organic matter and drainage is present. Strawberry ripens somewhat earlier on sandy soil than on clay soil. There is a definite cultivar adaptation to soils. Some grow better on heavier soils and others on light soils. Water should not stagnate in the field. Since most of its roots are found in the top 15cm soil, keep this layer porous and rich in humus. Strawberry is not much sensitive to soil reaction. However, it prefers a slight acidic soil. At higher pH, there is less root growth. There should be no underlying lime layer up to 15–20cm, otherwise it causes burning of leaves. In drier areas, alkali soils must be avoided. Thus, sandy loam to loamy soil with pH 5.7–6.5 is ideal for strawberry cultivation.

 
Varieties

All the cultivated varieties of strawberry are octaploid. A number of cultivars have been introduced and evaluated from time-to-time. The promising ones are:

Chandler

Fruit is of exceptionally high dessert quality with outstanding colour and flavour. It is very resistant to physical damages caused by rain. Plants are tolerant to viruses. Fruits are large, flesh and skin firm and flavour excellent. It is suitable for fresh market and processing. On an average, berry weighs 15–18g. The fruits have good TSS (12%), acidity (0.85%), vitamin C (55.5mg/100g) and sugar content (6.1%).

Tioga

An early-maturing cultivar, it is tolerant to viruses. Fruits very large, flesh and skin firm, dessert and processing quality good, TSS 12.2%, acidity 0.98% and sugar 6.2%. Average berry weighs about 9g.

Torrey

Tolerant to viruses, it produces numerous runners. Fruits large, flesh and skin medium firm, dessert quality excellent, processing quality good, TSS 12.0%, acidity 0.97% and sugars 6.1%. Average berry weighs 6.9g.

Selva

A day-neutral cultivar, it has the capacity to produce off-season fruits. It is different from day-neutral or ever bearing types. Fruits large, flesh and skin firm, conic to blocky in shape, dessert quality good. It can be handled and shipped fairly well. Skin bright red, attractive, flesh red, internally somewhat hollow, light in colour at core, average berry weighs 15–18g, TSS 11.1%, acidity 1.0% and sugar 5.5%.

Belrubi

Fruits large, conical (necked fruit), skin bright red, flesh attractive red, somewhat firm, less hollow at core, high quality, sweet, slightly subacid, average berry weigh 15g, TSS 11.8%, acidity 0.98%, sugars 6%. Plant produces adequate runners.

Fern

It is a day-neutral, early-ripening and over-bearing cultivar. Fruits large, medium, conical, solid internally, slightly hollow, skin red, flesh red, firm, flavour excellent, suitable for fresh market and processing. It tastes sweet to slightly subacidic. Average berry weighs 20–25g, TSS 11.2%, acidity 0.88% and sugars 6.1%.

Pajaro

It is very successful under summer system. Plant tolerant to virus. Fruit has good dessert and processing quality. Fruit is quite susceptible to physical damage caused by rain. Fruits large, flesh very firm, skin firm, red colour, average berry weighs 7.6g, TSS 12.2%, acidity 0.97% and sugars 5.5%.

Besides, Premier, Red Coat, Local Jeolikot, Dilpasand, Bangalore, Florida 90, Katrain Sweet, Pusa Early Dwarf and Blakemore are also grown.

   
Propagation

Strawberry is commercially propagated by runner plants. Generally one plant produces 7–10 runners but under proper management, it can go up to 15 runners/plant. It can also be propagated through crowns (3–5 plants/crown), but division of crowns of older plants is too tedious and expensive for cultivars producing runner plants readily. Runner formation can be stimulated with the application of IBA (100ppm) 10 days before flowering, and also with Morphectin (50ppm).

Propagation by seed is not suitable as the seedlings do not come true-to-type. Due to this, old strawberry buds may have many untrue seedlings undesirable for propagation.

Where viruses and nematodes are present, primarily in commercial plantations, the growth and production of plants may be reduced by half or more. It is desirable to procure virus-free plants for commercial plantations. In addition, these plants are raised in fumigated soils to control nematodes. Planting virus and nematode-free stock, and keeping it clean provides protection against serious diseases.

For large-scale propagation of virus-free plants, tissue culture is widely used. Under favourable conditions, one strawberry meristem can be multiplied to yield more than one million plants in a year. Plants can be regenerated from meristematic callus, anthers and immature embryos.

   
Cultivation  

Planting

Soil preparation is very important for strawberry cultivation. It should start during summer when the soil is ploughed with a soil turning plough so that the insects present in soil may die. It should be followed by repeated ploughings to make soil friable. Remove weeds and stubbles. Since most of its roots are confined in top 40cm soil, the soil should be made friable. Deep cultivation improves water absorption by the crop. The weeds can also be controlled by applying paraquat. Soil should be fumigated before planting to control fungal diseases, particularly verticillium wilt. Soil fumigation with a mixture of methyl bromide and chloropicrin helps increase root system, reduces N fertilizer requirement and controls several weeds.

September–October is ideal time of planting runners or crowns in hilly areas. The planting material should be healthy, disease and insect-free. Early formed, well-developed runners are ideal for planting. Fruit buds are established during the fall of the first season. The September–October planted plants are well-established in the field and start giving quality fruits in spring season. If the planting is done too early, plants lack vigour and result in low yield and quality of fruits. If planted very late, runners develop in March and crops are light. In Punjab and Haryana, planting during November is promising.

If planting is done in spring, use only healthy and vigorous plants. The larger the plants at the end of first season, the larger will be the succeeding crop.

In temperate humid regions, planting can be done in spring. If the weather is undesirable, plants can be stored in polythene bags at 31°–32°C until conditions are favourable. Cold storage plants usually grow as well as freshly dug field plants.

Strawberry can be planted by hand. However, care should be taken to prevent damage and drying of roots of runners. Runners are uprooted from nursery, made into bundles and planted in the field. These can also be kept in cold storage before transplanting. The soil should be frequently irrigated to reduce water stress in the leaf. Defoliation suppresses the plant growth, delays fruiting and reduces yield and quality.

Training

There are 4 training systems—matted row, spaced row, hill and plastic mulch. Generally matted row system is followed in our country.

Matted row: This is the simplest and least expensive method. The runners are usually planted at 90cm × 45cm spacing. In Himachal Pradesh, a spacing of 60cm × 25cm for Chandler is optimum. After the initial growth of the first year, runners are allowed to cover the vacant space all around the mother plants ultimately covering the whole vacant space and giving the appearance of a mat. It is generally followed in heavy soils which are free from weeds. In this system, more number of plants can be accommodated/unit area which give a higher yield under suitable conditions. The overcrowding may cause higher fruit rot. Thus care must be taken to maintain the optimum number of plants without overcrowding.

Spaced row: This system is suitable for cultivars that are moderate to weak in producing runners. The daughter plants are spaced at definite distances by covering the selected tips of runners with soil which become plants. This is done till the desired number of daughter plants are obtained for each mother plant. The runners formed later on are removed.

Hill system: This system is followed for the cultivars developing a few runners. All runners are removed from the mother plants. The individual plants
become large and bear more than those in matted row. The plants are planted 25–30cm apart in twin rows 20–30cm apart and 100–110cm spacing between twin rows. A small tractor can be used for tillage. Where cultivation is done manually, the rows can be spaced closer at 60cm. In some cases triple rows are set.

Plastic film: Green or black plastic film is used as a mulch for the hill system to control weeds and conserve moisture, but on hot days, some scalding of berries takes place. In this system, berries are kept clean and rot and mold are reduced. The plants bloom earlier. These are prone to damage by frost.

Manuring and fertilization

There are different recommendations for strawberry grown in different states in India. In Himachal Pradesh, application of 50 tonnes farmyard manure along with 40kg each of P 2 O 5 and K 2 O/ha at the time of preparation of beds is recommended. The N (80kg) should be applied in 2 split doses; half in September or after the establishment of plants in September–October, and the remaining half before blooming.

For Uttar Pradesh hills, apply farmyard manure (25–37.5 tonnes), N (75–100kg), P 2 O 5   (80–120kg), K 2 O (50–80kg)/ha. The farmyard manure should be mixed in soil at the time of preparation of planting bed. Full dose of P 2 O 5   and half of K 2 O are placed in the planting rows at 15–20cm depth. Half N should be broadcast in inter-row spaces a month after planting and the remaining half N and K 2 O should be sidedressed at the time of flowering. Foliar spraying of N (0.5%), P 2 O 5   (0.2%) and K 2 O (0.5%), 4 times between August and February is also advised.

Aftercare

The flower stems should be removed as they appear on plants after planting. If not removed, flowers create a drain on the plants, reducing their vitality, number and size of daughter plants. This practice also helps establish the plants and aids in tolerating heat and drought. The removal of flower strains from cultivars which produce small number of daughter plants increases the number of runners and plant set.

In Hill system, runners should be cut as and when they appear. With matted row system, surplus plants should be removed from outside the rows during late summer or autumn. The operation can be performed normally or with the help of cultivar and other specialized machinery.

Keep the crop weed-free during first season by cultivating, applying herbicides, or plastic sheet. The soil should be worked towards the plants. It should be ensured that soil remains around the crown without covering them. Cultivation should be restricted to only upper 2.54–5.08cm of the soil. It should be continued till the straw mulch is applied (where it is used). Weeds should not be allowed to grow. Emergence of weeds during the fruiting season also affects pollination by honey bees, thereby reducing yields drastically.

Irrigation

Irrigation is a must and in humid regions, even short droughts reduce the yield, damaging the shallow root system. Since strawberry is a shallow-rooted plant, the plants require more frequent but less amount of water in each irrigation. Irrigation of newly-planted buds results in increased runner production and early rooting. Strawberry plants produce optimum growth when the soil moisture tension is maintained at less than 1.0 atmosphere. Excessive irrigation is, however, detrimental which encourages growth of leaves and stolens at the expense of fruits and flowers and also increases the incidence of Botrytis rot.

Irrigation should be applied in furrows between the rows. The alleys are usually cultivated after 2–3 days of each irrigation. Care should be taken that water should not wet the leaves and fruits as it may increase the incidence of fungal infection. To obtain better fruit size and quality, it should be irrigated judiciously during harvesting.

Nowadays trickle and sprinkler irrigation systems are becoming popular. In trickle irrigation, 30% water and energy are saved. Less disruption of picking schedules, better water supply during winter and less rotting of strawberries and saving in water are added advantages. Sprinkler irrigation is, however, valuable in areas where there may be heat stress (>85°C temperature) and need for frost control using 50ppm water.

   
Harvesting & Postharvest management

Strawberries are generally harvested when half to three-fourths of skin develops colour. For distant shipment green or white and still hard berries are harvested. Delaying in picking usually increases the proportion of overripe and rotted berries. The picking duration differs from cultivar-to-cultivar. It is 55, 35 and 32 days for Tioga; 55, 30 and 30 days for Torrey during first, second and third year respectively in Himachal Pradesh. For Haryana conditions, it is 53 days for Tioga and 43 days for Torrey. Depending upon the weather conditions, picking should be done every second or third day. Ripening is faster in hot weather. Do not leave any ripe or rotted berry in the field. Berries should be picked along with a small stem portion attached. Picking should be done in the morning. It facilitates better shelf-life. Thus a yield of 96.53, 47.52, 52.01, 47.83 and 44.24q/ha from strawberry Tioga, Torrey, Howard 17, Catskill and Blakemore respectively may be taken. However, with proper fertilizer management an average yield of 175–300q/ha may be taken.

Some plant bioregulators—GA 3 (50ppm) sprayed 4 days after flowering, and maleic hydrazide (0.1–0.3%) sprayed after flowering increase yield up to 31–41%. Morphectin (50ppm) improves the fruit size.

Strawberries are harvested in small trays or baskets. They should be kept in a shady place to avoid damage due to excessive heat in the open field.

For distant marketing, strawberries should be precooled at 4°C within 2hr of harvesting and kept at the same temperature. After precooling, they are shipped in refrigerated vans.

Strawberries can be stored in cold storage at 32°C up to 10 days. Afterwards they lose their fresh bright colour, showing some shrivelling and deterioration in flavour. Strawberry fruit can be frozen for their processed products or as dessert. The strawberries having high flavour and bright red colour—Olympus, Hood and Shuksan—are quite suitable for ice-cream making, whereas those of Midway, Midland, Cardinal, Hood, Redchief and Beauty are ideal for processing.

   
Physiological Disorders
Albinism is a physiological disorder in strawberry due to lack of fruit colour during ripening. Fruits remain irregularly pink or even totally white and sometimes swollen. They have acid taste and become less firm. Albino fruits are often damaged during harvesting and are susceptible to Botrytis infection and decay during storage. It is probably caused by certain climatic conditions and extremes in nutrition.
Nutritional Value
 
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Chromosome Number: 90
Taxonomic Classification
Class
:
Magnoliopsida
Order
:
Solanales
Family
:
Convolvulaceae
Genus
:
Ipomoea
 
Sweet potato occupies a prime place in terms of calories production/unit area and time. It is grown as a starchy food crop throughout the tropical, subtropical and frost-free temperate climatic zone in the world. India ranks sixth in area but the productivity is very low (8.2 tonnes/ha), lower than the world productivity level. Orissa, Bihar, Uttar Pradesh and Madhya Pradesh—the leading states in sweet potato cultivation—have not been attentive towards development of food and feed products based on sweet potato. Though area under sweet potato has decreased, its productivity has increased from 7.2–8.2 tonnes/ha. Orissa has the largest area followed by Bihar, Uttar Pradesh, Assam, Madhya Pradesh, West Bengal and Maharashtra.
   
Climate and soil  

Moderately warm climate and temperature of 21°–26°C is very conducive to sweet potato cultivation. It is widely grown in tropical, subtropical and warm temperate areas, up to 2,200m above mean sea-level. A well-distributed annual rainfall of 75–150cm is favourable for its cultivation. It can tolerate drought to some extent but cannot withstand waterlogging. It requires plenty of sunshine, whereas shade causes reduction in yield. Even slight frost and temperature below 10°C checks its growth and development of tubers. Excess of rainfall and long photoperiod encourages vine growth, reducing tuber yield.

Well-drained loam and clay loam soils are good for sweet potato. Though it grows on a variety of soils, sandy loam with clay sub-soil is ideal. Heavy clay reduces its yield due to poor aeration. Compact soil checks development of tubers and highly sandy soil encourages long cylindrical pencil like tubers. Soil pH of 5.2–6.7 is appropriate for sweet potato. High pH invites pox and scurf diseases in sweet potato. Sweet potato is sensitive to alkaline and saline conditions. Slightly acidic soils with moderate fertility such as laterite soils of good depth may be suitable for its cultivation.

 
Varieties
The improved varieties have better yield, wider adaptability, early maturity and tolerance to stresses
   
Propagation

In India, sweet potato is generally propagated by fresh vine cuttings, directly obtained from field. To get sufficient planting material, nurseries are raised from selected tubers. Nursery-raised vines obtained from sprouted healthy tubers provide healthy planting material. Vines obtained from freshly-harvested tubers are also planted in nursery to get planting materials. In India, cuttings for direct planting are obtained from freshly-harvested vines of mature crop. This is commonly used method in areas where two crops are raised.

To raise primary nursery, medium-sized healthy tubers are planted. The nursery is prepared about 3 months before planting in the main field. For planting one hectare crop, about 100m 2 nursery is enough. About 100kg selected tubers are needed. A well-manured nursery with proper drainage and irrigation produces better planting material. Tubers are planted at a spacing of 25cm on ridges formed 60cm apart. The beds are manured and irrigated well. Application of urea @ 1.5kg/100m 2 ensures quick growth. For planting in the second nursery, vines are clipped off 40–45 days after planting. To plant one hectare crop, 500m 2 secondary nursery is required. The secondary nursery should also be well manured and maintained. Vines in secondary nursery should be planted at a spacing of 25cm on ridges 60cm apart. Apply 5kg urea in 2 split doses, 15 and 30 days after planting. The cuttings are made and planted in the main field 45 days after.

Vine cuttings (20–30cm long) obtained from top and middle portions having 3–4 nodes are ideal for planting. These cuttings should be stored in shade for 2 days to ensure better establishment in the field. If the planting material is sent to distant places, defoliation is recommended.

   
Cultivation  

Ploughing or digging the land to a depth of 15–20cm and bringing to a fine tilth are essential. Of the different methods, ridge-and-furrow method is mostly practised. It is more suitable than bed-and-flat method. The ridge-and-furrow method is helpful for convenient cultural operations, earthing-up and economical water requirements. Vines are planted at a spacing of 20–25cm on ridges of 20cm height, made 60cm apart. The middle portion of the vine with nodes is buried 5–10cm depth keeping both the ends exposed. About 82,000 cuttings are enough to plant one hectare area. The vines can be planted in inclined position with half of the length buried in the soil. A spacing of 30cm × 30cm is better for Indo-Gangetic plains, whereas a spacing of 45cm × 45cm is ideal for diara land in Bihar.

Sweet potato is often grown as a rainfed crop mostly in rainy season. In eastern India, it is being grown as autumn crop. Under irrigated conditions, this crop is grown in other periods also.

Cropping pattern based on sweet potato is quite profitable in northern Bihar. The ideal sequences are: maize ( kharif )–sweet potato (autumn with early cultivar); wheat ( rabi )–greengram (summer); and maize–sweet potato–onion. With these cropping patterns, a net income of more than Rs 20,000/ha has been obtained. In Tamil Nadu, sweet potato is followed by a cereal crop. In Kerala, under lowland, rice–rice–sweet potato; and in upland rice–sweet potato–fallow are common rotations.

Training and pruning

Sweet potato establishes 10 days after planting. It starts growing vigorously after third week. It should be turned to avoid anchoring the soil at nodes 30 days after planting. This is essential to check vegetative growth and to enhance tuber yield. The turning of vines should also be done at the time of second interculture to check luxuriant growth. Pruning of 15cm of top vine 60 days after planting does not affect the yield.

Manuring and fertilization

Application of 10 tonnes farmyard manure or compost and 75kg/ha each of N and K and 50kg/ha of P is recommended for the lowland conditions. The farmyard manure or compost @ 5 tonnes/ha may be applied at the time of preparation of upland. N:P:K @ 50, 25 and 50kg/ha should also be added under Kerala conditions. With farmyard manure or compost (10 tonnes/ha), 40–60kg/ha each of N and K and 40kg/ha of P is optimum for Bihar, West Bengal and Assam. While 60, 60 and 60kg N, P and K/ha is recommended for Andhra Pradesh and 60, 90 and 60kg/ha of NPK for Karnataka. A full dose of P and half of N and K as basal dose at the time of planting and the remaining half 30 days after planting along with weeding and earthing-up is recommended. The application of two-thirds recommended dose of N (26kg/ha) and 2kg Azospirillium to soil gives higher tuber yield. There is no specific recommendation on micronutrients requirements. However, in Bihar, application of ZnSO 4 @ 12.5kg/ha increases the yield.

Aftercare

Intercultural operation is essential for primary growth of sweet potato. The first intercultural operation 30 days after planting along with weeding and earthing-up improves the physical condition of soil. The second intercultural operation and earthing-up should be done 45–60 days after planting. There is a remarkable increase in tuber yield by spraying plant-growth regulator cycocel @ 500–1,000ppm 30 and 45 days after planting in Bihar, West Bengal, Assam, Maharashtra and Andhra Pradesh. The application of cycocel retards vegetative growth, causing substantial increase in tuber yield.

Irrigation

In India, sweet potato is mostly grown as a rainfed crop. For establishment of cuttings, sufficient soil moisture is desired. Planting is to be followed by irrigation to keep the field moist for 4–5 days. If there is insufficient moisture, irrigation may be given at 10–15 days interval. In Telangana region of Andhra Pradesh, during rabi season, 4–5 irrigations result in higher tuber yield. In north India, during dry weather, 2–4 irrigations may be given to get better yield.

   
Harvesting & Postharvest management

Sweet potato matures three-and-a-half to four-and-a-half months after planting. Harvesting sweet potato 120 days after planting is normally recommended. Delay in harvesting invites attack of sweet potato weevil. Maturity is indicated when the leaves turn yellow and begin to fall. By cutting tubers and verifying that latex dries up without turning black indicates its maturity. For easing operation, light irrigation is given 2–3 days before digging of tubers. Care should be taken to avoid injuries and bruises on tubers. Early cultivars can be harvested 90–105 days after planting, whereas medium-maturing 110 days after. Late harvesting is practised in diara land as the soil is sandy. For marketing of fresh tubers, cleaning and grading should be done to get better prices. By adopting recommended varieties and improved cultural practices, a yield up to 30 tonnes/ha may be obtained.

After harvest, tubers are spread in partial shade for 5–6 days, for healing and curing. They should be stored in semi-dark condition in a well-ventilated room. This type of storage invites infestation of pests and diseases. The shrinkage of tubers is also recorded due to dehydration. In some parts of the country, tubers are stored in a layer of dry sand/soil after curing under ambient conditions. For storing, graded tubers free from sweet potato weevil and bruises should be selected. Farmers store the graded tubers by keeping in a pit shade and covering the pit with paddy straw. Finally, the heap is plastered with mud or cowdung slurry. Tribal farmers of Koraput district of Orissa store their sweet potatoes by heaping the tubers in a corner of their huts and covering the heap with a thin layer of paddy straw. This heap is plastered with soil cowdung paste.

   
Physiological Disorders
There is no specific physiological disorder occurring in sweet potato. However, some varieties have a tendency to crack at maturity. This is usually due to excessive soil moisture or moisture shortage. Cracking also takes place if harvesting is delayed. The application of K checks tendency of cracking in tubers.
Nutritional Value
 
 
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