Introduction
Apple (Malus x domestica Borkh) carrying basic chromosome number X=17 is a complex inter specific hybrid which may have arisen through hybridization with Malus species indigenous to China. Apple is a member of family Rosaceae. Mostly apple cultivars are diploid, self incompatible and easily cross pollinated but some triploid and tetraploid cultivars are also available in the apple growing areas of the world.
Nutritional Values and uses of Apple
The nutrients contents of fresh apple fruits are shown in the table-1. The fruit is very rich in potassium and good source of phosphorus, magnesium, iron and calcium.
Table1: Nutritive Value of apple (Source-USDA-National Nutrient Database)
Nutrients | Value/100g Apple |
|---|---|
Water | 85.56 g |
Energy | 52 kcal |
Protein | 0.26 g |
Total lipid(fat) | 0.17 g |
Carbohydrates | 13.81g |
Fiber | 2.4 g |
Total sugar | 10.39 g |
Calcium (Ca) | 6 mg |
Iron (Fe) | 0.12 mg |
Magnesium (Mg) | 5 mg |
Phosphorus (P) | 11 mg |
Potassium (K) | 107 mg |
Vitamin C | 4.6 mg |
Niacin | 0.091 mg |
The fruit is used for fresh consumption and popular as dessert. A variety of palatable processed products are also prepared from apple fruits like jam, preserve and cider.
Apple Origin and Distribution
The primary center of origin of apple is central Asia specially Almaty and Kazakhstan. Almaty is a city in Kazakhstan and in Kazakh language almaty means city of apple tree. The region of apple origin includes Asia minor, soviet central Asia, Himalayan India & Pakistan which was introduced to western world via Persia. The Greeks and Romans domesticated apple and from there it reached to Europe and European settlers introduced apple to new world during the sixteenth century. The famous Ambri apple of Kashmir is said to be native to India.
Area, Production and Export of Apple
Apple is cultivated over 47.28 lakh hectare area with annual production of 695.7 lakh MT in the world (FAO 2010). China is world’s largest producer with 332.7 lakh MT annual production and UAS ranks second and produces 42.12 lakh MT. China alone produces 47% of word’s apple. India occupies 5th position and contributes only 4.1% to world apple production.
In India total area under apple cultivation was 2.89 lakh hectares with 28.91 lakh MT total production in 2010-11 (NHB-2011). Apple shares 4.5% of total fruit cultivation area and contributes 3.9% to total fruit production of India. The Jammu & Kashmir, Himachal Pradesh, and Uttaranchal are the main apple producing states and producing 64%, 31% and 4.7% apple of the country, respectively (NHB-2011). Apple is being also grown in some parts of Arunachal Pradesh, Sikkim, Nagaland and Meghalaya in North East India. India exported total 47075 MT apples worth Rs. 597.45 million during 2010-11 to Bangladesh, Nepal, UAE, Maldives, Liberia and Singapore. The highest 88% of total exported quantity is exported to Bangladesh followed by 9% to Nepal (NHB-2011).
Important Cultivars of Apple
There are over 6000 regionally important cultivars and races of apple across the world. Among the world apple cultivars Fuji (Ralls Janet x Delicious) of Japan is at number one contributing 14.1 million tones to total production. Red Delicious (Chance seedling) of USA, Golden delicious (Chance seedling) of USA and Gala (Kidd’s Orange X Golden Delicious) have got 2nd, 3rd and 4th position with 9.3, 8.8 and 3.8 million tones production, respectively. In India Delicious group of apple cultivars contributing about 60 to 70% to total apple production but these varieties are self-unfruitful and need pollinizers. The Red Delicious, Maharaji, Golden Delicious and Ambri cultivars are being mainly cultivated in J & K. The Delicious apples were introduced at Shimla in 1925 from USA while Fuji and Gala were introduced during 1995 in the country. The following are the suitable cultivars of apple:
Early Season Apples
Irish Peach, Benoni, Starkrimson, Tydeman’s Early, Michael Molies, Delicious, Schlomit, Early Shanburry, Fenny Benoni, Chaubattia Princess, Sun Set and Staymard.
Mid Season Apples
American Mother, Razakwar, Jonathan, Cox’s Orange, Pippin, Red Gold, Queen’s Apple, Rome Beauty, Scarlet Siberian, Starking Delicious, Red Chief, Oregon Spor, Red Spur, McIntosh, Cortland, Rich-a-Red, Wine Sap, Firdous, Shireen and Ben Davis.
Late Season Apples
King Pippin, American Apirouge, Kerry Pippin, Sunhari, Chamure, Golden Delicious, Red Delicious, Ambri Baldwin, Lal Ambri, Yellow Newton, Winter Banana, Granny Smith, Rymer and Buckingham.
Low Chilling Cultivars of Apple
These cultivars need less than 800 hours of winter chilling at less than 70C temperature due to which they can be cultivated at locations experiencing mild winter. Tropical Beauty, Parlin’s Beauty, Tamar, Vered, Naomi, Maayan, Michal, Anna and Shlomit are the main low chilling cultivars.
Apple Pollinizers
The pollinizer is a cultivar which produces viable pollen compatible with other cultivars whereas pollinator is an agent carrying pollen from one flower to another such as bees and insect in apple. The compatible pollination is essential for fruit setting in apple but most of the apple cultivars are self-incompatible due to which they need compatible poliinizers. The cultivars used as pollinizers should be compatible with others, producing huge pollens, flowering longer duration, synchronizing flowering with main cultivars and regular in bearing behavior. Depending upon occurrence of weather in the area 11 to 33 per cent pollinizers are planted in the apple orchard. Usually every third tree in every third row should be a pollinizer for enough pollination. The 8 bee hive are recommended for high density orchards and orchards having less than 15% pollonizer plants whereas 2-3 hives are sufficient for orchards more than 30% pollonizers. The Tydeman’s Early Worcester, Summer Queen as well as Early Shanburry are early bloomer and good pollinizer for early cultivars likewise Spartan, Red Gold, Lord Lambourne, Ginger Gold, Winter Banana, Gala, Cox Orange and McIntosh are good for mid season cultivars while Golden Delicious, Sunhari, More Spur Gold, Golden Spur, Granny Smith, Golden Hornet and Commercial are suitable pollinizer for late cultivars.
Spur cultivars: Red Chief, Starkrimson, Well Spur, Silver Spur, Bright N Early, Golden Spur, Starspur Golden, Red Spur, Ruby Red, Hardi Spur, Ultra Red, Supreme, Atwood and Wellspur. The Summer Queen, Manchurian, Red Flesh, Snow Drift and Golden Hornet are the good pollinizers for spur cultivars.
Crab Apple
The crab apples bear flower both on the spur as well as on one-year-old shoots. The spurs bloom first followed by shoots that gives longer duration of flowerings. In addition, crab apples are regular in flowering with high bloom index. Manchurian crab, Japanese crab, Red Flesh, Snow Drift and Golden Hornet are the promising crabs apples.
Coloured Strains of Apple
Top Red, Hi Red, Vance Delicious and Hardeman.
Scab resistant cultivars of Apple
Priscilla, Sir Prize, Macfree, Freedom, Coop-12, Coop-13, Firdous and Shireen.
Processing Cultivars of Apple
Delicious groups, Granny Smith, Liberty, Rome Beauty, York Imperial, Stayman, Winesap, Northern Spy, Prima, Sir Prize, Freedom, Red Free, Summer Red, McIntosh, Maharaji and Prima.
Climate for Apple
Apple is a typical temperate zone fruit which requires 1000 to 1600 hrs chilling below to 70C temperature in winter to break the rest period. Temperature during flowering plays important role in yield and quality of the fruits and the range of temperature from 100C- 200C in April results good fruit set and quality. Shading effect reduces red colour of fruits’ peel because anthocyanin content of peel is influenced by light.
Soil for Apple
The deep, rich in organic matter content, good water holding capacity and well drained loamy soil is suitable for apple orchard. Apple plants suffer from K and Mg deficiency on light soil whereas on calcareous soils plants suffer from Fe and Mn deficiency. The soil pH should be between 5.5 and 6.8. Under water logging roots rot and premature plants death takes place.
Apple Propagation
The main reasons of low productivity of apple are non availability of quality planting materials and existence of old, senile seedling orchards. Total 5.5 million plants of elite cultivars on clonal or standard seedling rootstocks are required for replacement of old unproductive orchards in the country but only 40 to 50% of this requirement is meeting from public and private nurseries (Ahmed et al., 2008). The productivity may be increased by using quality planting materials along with using Good Horticultural Practices (GHP) in the management of apple orchards.
Apple Root Stocks
The root stock anchors plant in soil, absorbs water and mineral nutrients from the soil and synthesis the plant hormones. The apple root stocks may be grouped into following two groups:
Seedling Root Stocks of Apple
The clonal root stocks of the apple have been introduced into India during early 1960s, however most of the commercial orchards of apple are still raised on seedling root stocks of crab apple ( Malus baccata) and Maharaji. The seeds are stratified below 70C in moist sand during December there after sown in raised bed during February-March in rows at 10x5cm spacing at 2-3 cm depth. Beds are covered with straw or dry leaves after sowing and irrigated. The cover protects seeds from frost and heavy rains. The one-year-old seedlings become ready for grafting in March-April. Under open condition sub-zero winter temperature and high wing velocity from November to April kills most of the seedling stocks in nursery. To avoid the problem stratified seeds are sown in beds under polyhouse and grafting is done next year during March-April (Singh, 2010). The use of seedling root stocks should be discouraged due to its genetic variability, vigorous nature, susceptibility to pests and diseases and inability to maintain uniformity in scion growth.
Clonal Root Stocks of Apple
The clonal root stocks of apple have been developed at various apple research stations of the world to meet the specific requirement like cold hardiness, salts tolerance, dwarf plant, resistance to certain pests and diseases, uniformity in scion growth, precocity and quality of fruits. The clonal root stocks of apple are multiplied through stooling. In stooling layers are separated from the mother plant after rooting and transplanted in nursery bed during December. About 1cm thick root stocks are used for grafting of scion in February- March. The developed clonal root stocks are further classified into following categories depending on their various characteristics:
Malling Series Apple Root Stocks
It is also called M series. The clonal root stocks of the series have been developed at East Malling Research Station of England in 1913. The name of M series rot stocks starts with prefix word ‘M’ which indicates that clonal root stock is develop at East Malling Research Station. The M series root stocks are further classified as under on the basis of vigor:
Very-dwarfing
M-27which was developed by Herry Mark Tydeman in 1929 from a cross between M-9 and M-13. It can be planted at 0.5X1.5 m spacing.
Dwarfing
M-8, M-9, M-26. M-9 is a chance seedling and susceptible to cold injury. M-26 is developed hybridization of M-16 and M-9.
Semi dwarfing
M-2, M-4 and M-7 (tolerant to excess moisture)
Semi Vigorous
M-13 (tolerant to excess moisture)
Vigorous
M-12 and M-16
Malling-Merton Series Apple Root Stocks
It is also called MM series and root stocks of the series carrying prefix MM. These clonal root stocks are resistant to woolly aphid and developed by crossing Malling series rootstocks with Northern Spy cultivar of apple. On the basis of vigor, they have been grouped as under:
Semi-dwarf
MM-106. It is most widely used rootstock developed from a cross between M-2 and Northern Spy.
Semi-vigorous
MM-104 and MM-111. MM-104 is also cross between M-2 and Northern Spy and tolerant to excess moisture while MM-111 is cross between Northern Spy and Merton-793 and drought resistant.
Vigorous
MM-109
Merton Series Apple Root Stocks
Merton-778, Merton-779, Merton-789 and Merton-793. Out of these root stocks Merton- 793is very useful because it is resistant to woolly aphid and collar root, having wide range of adoptability and induces early fruiting.
Polish or P series Apple Root Stocks
The P-series rootstocks of apple have been developed in Poland by making cross between common Antonovka and M-9. The five P-1, P-2, P-16, P-18 and P-22 winter hardy and crown rot resistant root stocks are developed in which P-18 is semi-dwarfing and rest are dwarfing while P-2 and P-22 are dwarfing inter stocks. All these rootstocks are susceptible to fire blight disease of apple.
Ottawa Series Apple Root Stocks
Ottawa series of apple rootstocks developed in Canada in which Ottawa hybrid seedlings carrying OH prefix name and Ottawa clonal series carrying O prefix name. In OH-series OH-1 to OH-6 are resistant to latent viruses and in O-series O-1 and O-14 are found promising. The root stocks of these series are still under test.
Budagovsky Series Apple Root Stocks
The Michurin collage of Horticulture, Russia introduced the Budagovsky or Bud series root stocks. In the series Bud-9 is dwarfing and resistant to crown rot, Bud-490 is semi-dwarfing, very cold hardy and resistant to crown rot whereas Bud-491 is dwarfing and very cold hardy.
Michigan Clone Series Root Stocks of Apple
This series is also called MAC series. The MAC-1 is free from suckering, MAC-9 or Mark similar to M-9 in vigor and productivity and MAC- 24 is semi-vigorous and well anchored in soil.
Other Important Root Stocks of Apple
Bemali
It is highly productive, resistant to woolly aphids, similar to M-26 in vigor and developed in Sweden.
Jork-9
J-9 developed in Germany from an open pollinated M-9 seedling. J-9 is easy to propagate.
Alnarp-2
Introduced from Sweden it is winter hardy, vigorous and induces early bearing.
Robusta-5
It is vigorous, winter hardy fire blight resistant and introduced from Canada.
Sub clones of M-9
The new sub clones of M-9 such as Pajam-1 and pajam-2 in France, KI-29 in Belgium, Fleuron-56 and NAKB series in Holland and Burgmer series in Germany have also been developed recently which are quite easy in multiplication.
Suitable Scion for Apple Propagation
The 1-year-old healthy shoots having 3-5 vegetative buds should be used as scion. The mother plants from which scions are collected should be of known pedigree, disease free, good bearing ability and of desired cultivars. The scions are collected from dormant plants in December and wrapped with moist moss grass. The scions are stored at 00C-50C and used in February- March for grafting.
Methods of Apple Propagation
Grafting on Apple
The tongue grafting is best method for apple propagation. The grafting should be done at 15-20 cm above ground level on the root stock during February –March. It is must to ensure the matching of cambium of scion and root stock before wrapping the graft union with polythene strip to get good success. The polythene strip should be removed from graft 6 weeks after grafting. The undesirable sprouts arising from rootstock below graft union should be removed to ensure better flow of metabolites to scion and get better success in grafting.
Budding on Apple
The ‘T’ and ‘Chip’ budding may be performed during July-August for apple propagated. The budding should be discouraged in apple propagation because of slow growth of budded plants in comparison to grafted one.
Planting: The pits of 1x1x1m size should be dug and filled at least one month before the planting. The top soil and sun soil of the pit should be piled separately during digging. The sub soil should be filled first following top soil filling to get the good fertile soil at bottom of the pit. The 50 kg well rotted FYM or compost and 500g single super phosphate per pit should be mixed thoroughly with soil before filling. The square or hexagonal planting system is suitable in flat areas while contour system of planting is best for sloping areas. The distance of planting is depending on agro-climate, soil fertility, cultivars, training and pruning system adopted and types of root stock. Normally 5-6 m spacing is kept for vigorous and semi dwarf root stocks and 1.5- 3.0m for very dwarf to dwarf root stocks. The 500 to 1500 plants /ha can be accommodated under high density planting.
Manures and Fertilizers Management in Apple
The manures and fertilizers dose varies according to age of tree, cultivars, soil and fruit bearing load. The soil and plant tissues analysis are the more reliable methods to determine the manures and fertilizers dose in apple. Normally 10kg FYM, 70g N, 35g P and 70g K per year should be applied in 1-year-old apple tree. Additional dose of equal amount should be increased every year up to 10 years thereafter dose is stabilized to 100 kg FYM, 700g N, 350g P and 700g K per plant per year for coming years. The full dose of FYM, P and K should be applied during December before snowfall and half dose of N should be applied during February-March. Rest half N should be applied during March-April just after fruit set. The manures and fertilizers should be mixed with soil covered by tree canopy leaving circular area of 30cm radius around the trunk. If deficiency symptoms appear micro nutrients like B, Zn, Mn and Ca should be sprayed at 0.1%, 0.5%, 0.4% and 0.5% concentrations, respectively.
Water Management in Apple
The critical period of water requirement in apple is after fruit set from April to August. Under rainfed conditions soil moisture should be conserved by mulching after rainfall during spring. In areas when irrigation facility is available apple plants should be irrigated at 8 days’ intervals during April to June before starting the pre-mansoon shower. The drip system of irrigation is best for water scare and sloping areas.
Clean cultivation in Apple
Under clean cultivation apple orchard is kept free from all types of weeds and vegetation. The clean cultivation is only possible by continuous weeding or use of weedicides (Paraquat 0.5%) because mechanical weeding is not easy on sloping land and terraces. The clean cultivation is recommended to young non-bearing orchard to check the competition between young apple tree and weeds for nutrients and moisture since young tree and weeds both absorb nutrients and water from upper layer of soil. In bearing orchard when tree roots penetrate deeper clean cultivation is not suitable because it increases moisture loss, fertile soil erosion and decreases humus content in soil. The weeding should not be done even in non-bearing young orchard during rainy season.
Sod Culture in Apple
In sod culture practice, suitable sod (cover grass) is grown in apple orchard and no tilling is done however some time soil is raked to improve the aeration and water absorption capacity. The legumes like Kudzu vine (Pueraria sp.), alfalfa (Medicago sativa), subterranean clover (Trifoliun subterraneum) and non-legumes like Timothy grass (Phleum pretense), orchard grass (Dactylis glomerata) and Kentucky blue grass (Poa pratensis) are grown for sod cultivation. Sod cultivation checks soil erosion and increases soil humus but causing competition between sod & trees for nutrients and moisture.
Mulching in Apple
The covering of soil with organic materials like straw, dry leaves, hay or inorganic materials such as polythene sheet is called mulching. Mulching reduces soil moisture loss through evaporation, discourages weeds emergence, maintain soil temperature and organic mulches increase soil organic matter content. Mulching also reduces soil erosion and provides cushion for fruits falling from the tree thereby minimizes the fruits damage.
Apple Crop Regulation
Fruit setting: In apple often yield is adversely affected due to less fruit setting. The spray of Miraculan @ 0.75ml/l of water or Biozyme/ Protozyme@ 2ml/l water at bud swell and petal fall stages improves the fruit setting in apple.
Fruit thinning: It is practiced to avoid over cropping and to improve fruit quality. Hand thinning of flower cluster is done to retain 2-3 fruit lets per cluster. Spraying of 10ppm NAA at petal fall stage or at 15 mm fruit length is effective in fruit thinning.
Fruit drop: The three waves of fruit drops have been observed in apple. The first wave comes during early stage just after fruit set due to water stress, hail storms, poor pollination and improper fertilization; Second wave appears in June when fruit competes for nutrients and water under moisture stress condition in June and third waves, which causes economic loss, comes at pre harvest stage due to physiological reasons or any disorder. The application of 10ppm NAA (Planofix 1ml/4.5l water) one week before expected fruit drop wave controls the fruit drop effectively.
Inspect and pests
1- San Jose Scale (Quadraspidiotus perniciosus): It is notorious pest of apple which is named as San Jose Scale because pest first attracted the attention of growers at San Jose in California during 1873. It damages all parts of the apple plant above the ground level by sucking cell sap. Insects form dense colonies on the plant parts and reddish or pinkish rings appear on the fruits and Twigs. Infested twigs may die within few months.
The parasitoids Encarsia perniciosi, Aphiitis sp., Chiloneurus sp. and predators Chilocrus bijugas, Coccinella septumpunctata are used to destroy the San Jose scale colonies. The insect is also controlled by spraying of 2-3% mineral oil or 4-5% diesel oil emulsion on dormant tree during winter. Single spray of 0.02% chloropyriphos 20 EC or 0.03% dimethoate 30EC at first crawler emergence stage during May is also recommended to control San Jose Scale.
2- Woolly aphid (Eriosoma lanigerum): It is serious pest in apple growing areas. The aphid is purplish in colour and covered with white cottony masses. It is active during March to December and multiply very fast. The nursery plants and young orchards are more prone to damage by woolly aphids. It feeds on sap of branches, twigs and roots of plant. Gall formation takes place at infested site due to excessive cell division. The affected plants loss its vigour and gives poor yield.
The infested planting materials should not be used to prevent the aphid. The parasitoids Aphelinus mali and predators Coccinella septumpunctata and Hippodamia variegare may be used to control the woolly aphids. The spraying of 0.03% dimethoate 30EC or monocrotophos 36SL once during March-April and second during June-July protects the areal parts of plant. The soil application of 10-30g phorate 10G or 30-50g carbofuran 3G per plant at 5 cm depth is advised to control the insect in the root zone of the plants. The woolly aphid resistance root stock Merton- 793 may be used for propagation.
3- European Red Mite: The mite is found in all apple growing areas of India. In addition to apple it also attacks on pear, peach, apricot, plum and almond. Mite suck cell sap from tender parts and leaves of the plant resulting premature leaves fall. It may cause up to 30% economic loss to the apple orchards.
The mites’ population may be controlled by predators Typhlodromous sp, Amblyseius sp. Zetzellia sp. and Crysoperla sp. Red mites can also be controlled effectively by spraying 0.05% lindane 20EC with 2% oil at pink bud stage and latter on whenever mite population exceeds 15-20 mites /leaf.
Diseases
Scab: Scab is caused by fungus Venturia inoequalis (Cke.) Wint. that attacks on foliage, blossom, young shoots, buds and fruits of apple. The velvety brown to olive green lesions appears on the affected parts of the plants. Attack of fungus on petioles and pedicels results premature dropping of the leaves and fruits. The fungus survives on affected fallen leaves of apple during winter when winter overcome and temperature increases the spores start germination on young leaves and fruits. The fungus enters into saprophytic phase after leaves fall in autumn to overcome the winter. The 7-8 protective sprays of non-systematic and systematic fungicides during growing season prevents the scab. After symptom appearance Carbendazim (0.05%) or Thiophanate Methyl (0.05%) should be sprayed thrice at 7-10 days’ interval to control the scab. Scab resistant cultivars such as Priscilla, Sir Prize, Macfree, Freedom, Coop-12, Coop-13, Firdous and Shireen should be preferred for cultivation.
Powdery mildew: It is serious disease of apple all over the world which is caused by fungus Podosphaera leucotricha (Ell. & Ev.) Salm. The small grayish or white patches appears on the under surface of leaves and latter on entire leaves are covered with mycelium and powdery mass of spores. The causal organism survives into dormant buds in mycelial form during winter. The fungus becomes active in early spring and produces disease symptoms. The 3-4 spraying of fungicides like Carbendazim (0.05%), Thiophanate Methyl (0.05%), Dinocap (0.10%), Bitertarnol (0.10%) at 7-14 days’ interval from the pink bud stage control the disease.
Root rot: The root rot is a serious problem of apple in Himachal Pradesh and Uttarakhand. The fungus Dematophora necatrix attacks on the roots particularly in rainy season resulting death of apple trees. The leaves of affected plant turn into yellow and bronze colour and falls aw well as bark raptures. The disease leads die back and ultimately plant die. New roots got infected through contact of infected soil, water and roots. To prevent the disease attack, the pits should be treated with 3% Formaldehyde 3 weeks before of the planting. The disease can be effectively controlled by soil drenching under the canopy of plant with Carbendazim 50 WP (0.1%) or Mancozeb+ Carbendazim 75 WP (0.5%) during rainy season. The Trichoderma viridae and T. herzianum are antagonistic to fungus D. necatrix these antagonistic fungi can be used as bio-agent to control the root rot. The damaged tree should be repaired by approach grafting with seedlings.
Cankers: The bark canker (Botryoshaeria dothidea), smokey blight canker (Diplodia seriata), Nail Head canker (Nummularia discreta) and silver leaf canker (Chondrostereum purpureum) are the important types of canker affecting the apple plants. Cankers cause fruit rotting, early defoliation, dieback of young twigs and girdling of branches resulting death of trees. The mechanical injury should be avoided and dead wood mummified fruits and pruned branches should be burnt to control the disease. The pruning wounds and mechanical injuries should be dressed with paste consisting with Carbendazim 50 WP, Mancozeb 75 WP or Copper-oxychloride 50 WP and linseed oil in 1:2:9 ratios. The spray of fungicides is also very effective to prevent the cankers.
Physiological disorders
Cork spot: The deficiency of calcium causes the cork spot that affects fruit quality and visual appeal. The small green dimples or depressions appear on the outer portion of the fruit flesh which turns into corky, brown and dry discoloured latter on. Mixing of calcium or limestone into soil effectively controls the cork spot.
Bitter pit: The young bearing trees and immature fruits are more susceptible to bitter pit in which small brown lesions of 2-10 mm diameter develop in the flesh of the fruits. The tissue below the peel becomes dark and corky. The spots develop fully after 1-2 months in storage and become darker and more sunken. The spraying of calcium 45 days before harvesting and calcium dips before storage of fruits control the problem of bitter pit.
Brown heart: The large and over mature fruits are susceptible to brown heart which increases when Co2 concentration increases above 1% in the storage. The browning of flesh near the core takes place and the symptoms develop early in storage that increases with storage period. To control the brown heart incident, the fruits should be harvested at proper maturity and stored below 1% Co2 concentration.
Scald: The inadequate ventilation in storage or in packaging boxes promotes this physiological disorder. In scald irregular brown patches of dead peel develop within 3-7 days after removal of fruits from cold storage and exposure to warm temperature but warm temperature does not cause the scald instead allow symptoms to develop from previous injury occurred during storage. The hot dry weather before harvesting, storage of immature fruits, high nitrogen and low calcium content in the fruits favour the scald development. The problem can be reduced by harvesting the fruits at proper maturity and maintaining ventilation in the cold storage. Application of antioxidant Diphenylamine (DPA) just after harvesting controls the scald problem.
Maturity indices, Harvesting and yield: The apple becomes ready to harvest 120-140 days after full bloom depending upon varieties. In India apple is harvested from July to November depending upon location and cultivar but best quality of apples is harvested around October at higher altitude of Jammu & Kashmir and Himanchal Pradesh. The T.S.S. of fruits varies from 12-14 % while fruit firmness varies from 8.2 to 8.7kg at fruit maturity. In India average productivity of apple is 10 tons /ha that can be increased up to 20-25 tones/ha
References:
Ahmed, N.; Das, B.; Verma, M.K. and Verma, R.K. (2008). Apple industries Challenges from Import. In: Recent Initiatives in Horticulture. K.L. Chadha, Sing, A.K. and Patel, V.B.(Eds.), Horticultureal Society of India, New Delhi.P.691-719.
Singh, H.P.(2010). Status of Production of quality seed and planting material in Horticultural crops. Indian Horticulture, 55(2):3-11.
Chadha, T.R. (2001). Textbook of temperate fruits. Directorate of Information and Publications of Agriculture, ICAR, New Delhi.
Bandy, F.A. and Sharma, M.K. (2010). Advances in Temperate Fruit Production. Kalyani Publishers, Ludhiyana.
FAO (2010)
NHB (2011)
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