🌸 Citrus - Classification,
Citrus.
This lesson explains citrus crop groups and core production practices, including orchard establishment and intercultural operations.
PLANTING, NUTRIENT AND WATER MANAGEMENT,
INTERCULTURAL OPERATIONS
CITRUS
Citrus spp. Family : Rutaceae
Citrus fruits include oranges lamons, limes, pummelo and grape fruit.Being a
native of tropical and subtropical region of South East Asia, these have been under
cultivation from time immemorial in South China, Malaya and sub-Himalayan parts of
Assam, From here, they spread to other tropical and subtropical parts of the world. Next
to mango and banana, citrus represents the third most important group of fruits in India.
The botanical classification of the genus is highly confusing since more and more inter
specific and inter generic hybrids are going on added to the list each on deserving a
separate species status.
All the edible fruits of citrus come under subgenus Eucitrus which can be divided
into 5 horticultural groups.
1. Acid group :
Acid lime : Citrus aurantifolia
Tahiti or Persean lime : Citrus latifolia
Rangpur lime : C. limonia
Lemon : Citrus limon
Rough lemon : C. jambhiri
Citron : C. medica (Kidarankai in
Tamil, used for pickling)
Sweet lime : Citrus limettoides
2. Orange group :
Sweet orange : Citrus sinensis
Sour orange : Citrus aurantium
(Narthankaai in Tamil, used for
pickling)
Multiple leaf orange : C. multifolia
Japanese summer grape fruit : C. natsudaidai
Mandarin group : (loose jacket)
Coorg mandarin, Nagpur
Santra and Kodai orange
: C. reticulata
Japanese Satsuma mandarin : C. unshiu
Willow leaf mandarin : C.deliciosa
King mandarin : C. nobilis
Kinnow mandarin : King x willow leaf
Tangerine orange var Dancy
(trifoliate x mandarins)
: Citrus tangerina
4. Pummelo and grape fruit group:
Pummelo : C. grandis
Grape fruit : C. paradisi
Kumquat : Fortunella sp.
- The fifth group consists of mainly hybrids of different citrus fruits with trifoliate orange
(Poncirus trifoliata) and mainly used as rootstock.
e.g. Citrange (Poncirus trifoliata x C. sinensis) var. Troyer, var. Carrizo
Citrangor (Citrange x C. sinensis)
Tangelo (Tangerine x grape fruit)
Citrangequat (Citrange x kumquat)
Mandarinorange: C. reticulata
The group of orange is otherwise called Kamala orange. Nagpur santra of Maharashtra,
Coorg of Karnataka and Kodai orange of Tamil Nadu. This group is characterized by the loose
skin of fruits.
Soil and climate
Subtropical 500-1500 m MSL elevation. A rainfall of about 150 cm to 250 cm is
required. The winter should be mild and there should be no strong or hot wind during summer.
A medium or light loam with a pH 5.5 to 6.5 would be ideal to grow.
Season : November – December
Planting: Seedligns and budded plants
Spacing: 6 x 6 m pit size 75 cm [3] planting during May-June and September – October.
Though the crop is grown as rainfed one, the young plants should be irrigated whenever
there is failure of monsoon as well as during summer season.
Manure and fertilizers
Applied twice in a year during June and October.
For Palani hills
| Manures & Fertilizers |
1year | II year | III year | IV year | V year | VI year on wards |
|---|---|---|---|---|---|---|
| FYM | 10 | 15 | 20 | 25 | 25 | 30 |
| N | 0.100 | 0.200 | 0.300 | 0.400 | 0.500 | 0.600 |
| P | 0.040 | 0.80 | 0.120 | 0.160 | 0.160 | 0.200 |
| K | 0.050 | 0.100 | 0.200 | 0.300 | 0.300 | 0.400 |
For shervaroyan hills (for trees above 6 years old)
700: 375:600 g/tree NPK along with VAM ( Glomus fasiculatus ) @ 1 kg/tree. Manures
are applied in the basin 70 cm away from the trunk and incorporated. Application of lime or
dolomite at 4 kg/tree during January – February once in 2-3 years (not mixed with chemical
fertilizer).
Micronutrient
ZnSO4 – 600 g
MnSO4 – 600 g
MgSO4 – 600 g
In 450 lit of water applied during new flush
FeSO4
- 600 g
After cultivation
Removal of water shoots
Rootstock sprouts
Dead and diseased shoots
Removal of laterals of the main stem upto 45 m from ground level
Basins should be provided for each tree with gradient slope.
Growth regulators
To increase the fruit retention spraying the trees at flowering and again at marble stage
with 2,4-D at 20 ppm or NAA 30 ppm.
Harvest: Starts bearing from 3-5 year after planting in budded plants. Incase of seedlings 5-7
years.
Yield: 15-20 t/ha/yr.
A small crop can be obtained from 4 year old tree and the yield will be higher from 7 [th]
year. From flowering to maturity it takes 9 months.
Varieties
- Kodai Orange ( Citrus reticulate )
Trees are vigorous, fruits are very small characterized by loose rind and medium
flavour. But it is a heavy seeded variety.
- Nagpur Santra ( Citrus reticulata )
It is the most important commercial cultivar of India. This cultivar is considered to
be one of the finest mandarins in the world orange vigorous growing variety. Fruits are
medium to subglobose having a loose rind. Flesh is fine textured with abundant juice.
Fruits mature in January – February.
- Coorg ( Citrus reticulata )
Medium to large fruits, bright orange with a loose rind. It has a good flavour,
ripens later than Nagpur Santra. It is a regular bearer. It is the commercial variety in the
coorg region of Karnataka.
In Darjeeling district of West Bengal, the variety grown is known as Darjeeling
orange and it is Desi in Punjab. In Sikkim, the mandarin cultivar grown is known as
‘Sumithira’ while in Meghalaya it is called as ‘Khasi Mandarin’ or ‘Sohniamtra’.
- Sastuma Mandarin ( Citrus unshiu )
It is a Japanese variety with small spreading tree. Fruits are seedless with thin rind
having orange colour at maturity. The quality of fruit is excellent with good blend of sugar
and acidity.
- King Mandarin ( Citrus nobilis )
It is a commercial variety of USA. The trees grow 5-6 M, petioles narrowly
winged small, flattened, orange, red fruits with distinctly sweet pulp which is juicy and f
excellent quality.
Willow Leaf Mandarin ( _ Citrus deliciosa _ )
It is another commercial variety of USA. Trees medium sized with drooping
growth habit. The distinctive characteristics are presence of mild and pleasant aromatic
flavour in fruit juice, plump spherical seeds, high degree of seed polyembryony and
marked alternate bearing tendency of the trees.
Kinnow (King x Willow leaf)
It is a hybrid between king and willow leaf mandarins. It was developed by Dr.
H.B. Frost at citrus Experiment Station, California 1915. It has performed very well in
Pakistan, Punjab, Uthrangal, Haryana, Karnataka and foot hills of Himachal Pradesh. This
hybrid cultivar produces excellent quality fruits and holds export potential. Fruit medium
in size, globose to slightly oblat, rind thin rather adherent for a mandarin but peelable,
tough and leathery, surface very smooth and glossy, colour yellowish orange at maturity.
Segments (9 to 10) do not separate easily, very juicy, flavour rich aromatic and distinctive,
TSS 10o brin, acidity 0.8%. Seeds numerous, (2 to 2H) polyembryonic and cotyledone
pale greenish yellow.
Dancy Tangerine ( _ Citrus tangerine _ )
This is the commercial variety of Florida in united states.
It was developed at the experiment station, California in 1915, with deliciola as the male parent. It was first introduced in Punjab.
Plants are medium to large, erect, symmetrical, with dense foliage and a few scattered spines; leaves are broadly lanceolate.
Khasi Mandrin
This cultivar is commercially grown in the North – East region of India. It is
mainly grown as seedling trees. The cultivar produces excellent quality fruits with
depressed globose bright orange, surface smooth and glossy, stalk end even or obtuse,
Occasionally short necked rind thick, adherence very slight, segments 8 to 13 usually 10,
pulp vesicle uniformly orange coloured coarse but melting, flavour agreeable, juiced
abundant and orange colour, sweetness and acidity well blended, seeds 10 to 15,
cotyledons green, polyembryonic.
10. Clementine:
This cultivar is native of Algeria. The cultivar is monoembrynic, matures early
and produces fruits of excellent quality.
11.Dancy:
Dancy is the most important cultivar of USA. It matures mid season, it is of
excellent quality, productive with a tendency to alternate bearing Dancy is closely related
to ladu and keonla cultivasrs of India.
12. Beaury:
It is a popular mandarin cultivar of Australia. The cultivar is similar to Dancy is
closely related to Ladu and keonla cultivars of India.
13. Campeona:
It is a large fruited mandarin cultivar of increasing importance in Argentina and
Uruguay.
14. Ellendale:
It is the principal late ripening cultivar of Australia. The fruits are large sized with
attractive colour and good keeping quality.
15. Emperor:
It is a leading cultivar of Australia Frit large, early mid season in maturity but
quality deteriorates rapidly if stored on tree after ripening.
Ponkan
Ponkan is the famous and highly reputed cultivar of South China and Formosa. It
is the foremost tropical mandarin cultivar, matures in mid-season, highly productive and
strongly alternate in bearing.
Desi
It is mainly grown in Punjab and adjoining hills of Himachal Pradesh. Fruits
orange colour uniform, golden yellow, rind medium thick some what thicker than coorg
mandarin, segments vary between 7 and 10; pulp light reddish yellow, texture tender,
sufficiently juicy, acidic but moderately flavored; seeds few, usually 3-7.
Darjeeling orange
Also known as sikkim orange and is cultivated widely in and around Darjeeling
hills. The trees are vigorous and prolific bearer. Fruits are relatively small in size,
somewhat flat in shape colour yellowish to orange when fully ripe; rind thin, adherence
little; juice plenty and sweet with good flavour ; seeds are few.
Propagation
Most of the Mandarin cultivars are propagated through seeds except
kinnow and Nagpur mandarins; usual practice in coorg, Assam and North Eastern hills
is to use seedlings as planting material. But with concerted efforts made to find out
suitable rootstocks for different regions, orchardists hare shifted to vegetative methods,
particularly T. budding because budded plants bear early, tolerant to biotic and abiotic
stress. The seedling trees not only bear late but also tend to become thorny and grow
tall and slender.
By seed
For quality planting material, select uniformly matured fruits from healthy,
true to type and heavy bearing plants to extract seeds. Freshly extracted seeds should
be mixed with ash and dried in shade otherwise, they may loose their liability seeds are
sown at a distance of 2 – 3cm. Germination may take place with in 3 – 4weeks. Since
the seeds are polyembryonic growth are rouged out and the rest that are produced from
the cells of nucleus are allowed to grow. The seedlings thus selected are more or less
uniform in growth and production.
By ‘ T ’ Budding
Budding is done using the buds of bud wood taken from the disease free
mother plants orn Rangpur lime, Cleopatra, Jatti khatti karna katta and Troyer citrange.
Rangpur lime is a vigorous, hardy rootstock with good adaptability to a wide range of
soil particularly heavy soil, tolerant to tristeza and salt; it is susceptible to footrot,
exocortis and xyloporosis. Cleopatra mandarin is the most salt tolerant root stock with
the ability to exclude sodium and chloride taken up by root system. It is tolerant to
tristezz, exocortis and fairly tolerant to foot rot. Rough lemon, well adapted to high
sandy soils. IT is susceptible to foot rot and scab and tolerant to tristeza. This is the
most important rootstock for light soils Troyer citranges are used in areas where cot of
hardiness and resistance to tristeza are necessary they are also resistant to foot rot but
susceptible to exocortis
Karna khatta ( _ Citrus karma _ )
It is extensively used as a root stock in North India.
Seeds of identified root stock for a particular area should be extracted from
fully matured, healthy fruits. They are sown in lined (10-15cm deep) on raised seed
beds inside a polyethylene house. About 1 – 2 months old seedlings are shifted to
secondary beds. These are finally budded when they attain a height of 25-30cm and 1
2cm diameter. Scion should be selected from healthy, vigorous, matures, virus free and
high yielding trees. They should also be free from water sprouts and chimeras.
Further use of dormant scion bud wood from past season’s growth is used after it has
hardened. The bud wood should be taken from round or cylindrical green twigs. T
budding is done on one and a half to 2 years old seedling. In about 6-9 months, the
budded plants will be ready for transplanting in the main field.
Cultivation
Planting : Generally, planting is done during monsoon in all mandarin growing areas i.e.,
June – December. In sub mountainous tracts, where planting is generally done on slopes,
proper terraces are necessary, while in plains the land should be leveled properly. Pits of
45 cubic centimeters are dug at a spacing of 6 x 6 m and filled with FYM, sand and top
soil and then basins are formed. The buddlings are planted in the center of the pits and
irrigated.
In N-E parts of India, Khasi mandarins are very closely spaced (4.5 x 4.5
m is ideal for kinnow budded on Jattikhatti. Kinnow can be grown successfully under
high density planting by using Troyer citrange as a rootstock and by spacing the plants 1.8
x 1.8 m, accommodating 3000 lr/ha. The optimum spacing for Nagpur mandarin is
6 x 6 m when budded on Rough lemon. In Karnataka, coorg mandarin on Trifoliate
orange and Rangpur lime can be planted at a distance of 5 x 5, and 6 x 6 m,
accommodating 400& 275 trees / ha respectively.
In Tamil Nadu, Mandarin are planted at a spacing of 6 x 6 m in 75 x 75 x 75cm
size pits. The planting seasons are May – June and September – October.
Training and Pruning
The water shoots and rootstock sprouts should be periodically removed. Trees are
trained to single stem with 4 – 6 well – spaced branches for making the basic framework.
Further no branches should be allowed from the trunk up to height of 45-50 cm from the
ground level. An ideal mandarin tree should be low headed with dome like crown.
The bearing trees require little or no pruning. Pruning of bearing trees consists of
removal of dead, diseased, criss-cross and weak branches. Removal of water shoots and
suckers of rootstocks is also highly essential. Pruning of non-bearing trees can be done at
any time of the year, but for bearing trees, the best time is after harvesting, during late
winter or early spring when these are in somewhat dormant stage.
Root pruning is also practiced in some parts of central and southern India to
regulate flowering season. However, such prunings are not beneficial in the long run.
Crop Regulation
In such and central India, mandarins bloom thrice a year. The February flowering
is known as ambe bahar; June flowering as mring bahar and October flowering as hast
bahar. Under such circumstances, plants give irregular and small crops at indefinite
intervals. To overcome this problem and to get fruitful yield in any of the 3 flowering
seasons’, treating mandarin trees has been practiced which is called resting or root
exposure or bahar treatment.
In this method, roots of the plant are exposed too sun by removing up to 7 -10 cm
soil around 40-60 cm radius of tree trunk. The water is withheld for a month or two before
flowering. As a result of water stress, leaves show wilting and fall on the ground. At this
stage the roots are again covered with a mixture of soil and FYM and irrigated
immediately. Subsequent irrigations are given at suitable intervals. Consequently, plants
give new vegetative growth, profuse flowering and fruiting. However, in light sandy and
shallow soils, exposure of roots should not be practiced and mere withholding of water for
2-3 weeks is sufficient for wilting and debilitation of trees.
It depends upon the choice of the grower as to which of the 3 bahars is to be taken
to get maximum profit. As the availability of water is a problem in central India during
April – May, the farmers prefer mrig bahar (June) so that the plants are forced to rest in
April – May.
Resting treatment is not feasible in North India, as mandarin plants normally rest in
winter and flower once a year. It is experienced that resting treatment in general is a
devitalizing process and should be resorted to only under the advice and direction of a
technical expert.
Manuring and Fertilizarion
Mandarin, like other citrus fruits also require judicious application of mineral
nutrients for proper growth, development and production of quality fruits. Mandarins also
require zinc, copper, manganese, iron, boron and molybdenum but not sodium and
chlorine, which are rather harmful for mandarins. Improper supply of nutrients may cause
serious disorders which may lead to orchard decline.
For palani Hills (Kg./ tree / Yr.)
Manures/
Fertilizers
1 yr II yr III yr IV yr V yr VI on wards
FYM 10 15 25 25 25 30
N 0.100 0.200 0.300 0.400 0.500 0.600
P 0.040 0.080 0.120 0.160 0.160 0.200
K 0.050 0.100 0.200 0.300 0.300 0.400
For Shervaroyan hills (For trees above 6 year old)
NPK @ 700:375:600 g/tree along with VAM @ 1 kg / tree.
The fertilizers are to be applied in two splits on in May-June and another in
September – October.
Manures are to applied in the basin 70 cm away from the trunk at a death of 10 cm,
with topsoil covered and irrigated.
In hilly areas where the pH is very low, depending upon the pH, 2 – 4 kg of lime or
dolomite should be applied for each tree once in 2 years, one month ahead of the
application of regular fertilizers.
The spray solution containing following micronutrients can be applied once in
three months at the time of new flesh production.
Zinc sulphate - 0.5%
Manganese - 0.05%
Iron - 0.25%
Magnesium - 0.5%
Boron - 0.1%
Molybdenum - 0.003%
In addition to that apply 50 g in each of ZnSo4 mn and Fe per tree per year.
Application of VAM @ 20g/tree will help to accumulate Phosphorus, Zn, Cu and
sulphur.
The Fertigation treatment consisting of 500:240:70 NPK dose with 20% depletion
of available water content found best to increase the highest conopy volume, fruit weight,
TSS, Juice & yield in Nagpur mandarin.
Intercropping
eg: pea, cowpea and blackgram.
Irrigation
In south India, mandarins are grown under rainfed conditions in high rain fall areas. In winter,
mandarins should be watered at 10-15 days intervals, while in summer at 5-7 days. In tarai
region of UP, soil has high moisture retention capacity, thus lesser number of irrigations are
required. However in Punjab, Haryana, Rajasthan and AP,more number of irrigations are
required.
Since root activity of mandarins is confined to a radial distance of 120 cm and to a depth of 24
cm, too much wetting should be avoided. Plants should be irrigated at 8-10 days intervals, during
drought (April – June in North India and October – December in South-Central India) Mandarins
are highly susceptible to water logging; therefore, stagnation of water around tree trunk should
be avoided. Water should also be free of salts.
Weed control
Weeds are a serious problem in mandarin nursery and young plantations Better way to eradicate
weeds is to use weedicides. Pre-emergence application of Diuron (5kg/ha) or Terbacil (4.5kg/ha)
or postemergence application of Atrazine (5-6 kg/ha) controls weeds significantly.
Others: Bromocil (6 kg/ha) – Mono & dicotweeds.
Glyph orate (5 lt/ha) – Perennial grasses
Simazine (5 kg /ha) - Perennial grasses
Harvest and yield
Generally, mandarins start bearing from the 4th year having 15-20 fruits/tree.
However, its trees attain the level of full bearing at the age of 7-10 years. From flowering
to maturity it takes 9 months.
Main harvesting periods of mandarin in different regions of India .
Region Main crop Off season
North –Western plants Dec - Feb ----
North –Eastern India Nov- Feb April - May
Central India Feb - March October - November
South India - Coorg December - April July - August
Nilgiris August - October Feb - March
In Tamil Nadu, the main season is November – December, Harvest should be done at right
maturity. Therefore, fruits should be harvested when they attain full size, develop attractive
colour with optimum sugar; acid blend.
Yield
About 1000 – 1500 fruits can be harvested from a tree per year and 15 –20t/ha/year. The
common practice of harvesting is to pull the fruits from the branch, which may rupture the skin
near the stem-end leading to fungal infection and rotting. Therefore, fruits should neither be
plucked nor torn off, but should be cut off with clippers, shears or secateurs. Although mandarins
may attain optimum maturity standard but the fruits may not be attractive at the time of
harvesting due to lack of good yellow colour. Accordingly, degreening of mandarins with the
application of ethrel (50 ppm) one week before the harvesting develop golden yellow colour
within 5 days of the treatment.
Grading and Packing:
Generally mandarins and graded according to their size and appearance. Fruits are usually
packed in wooden boxes for distant markets, while for local marketing; baskets of
split bamboo and mulberry are used. Chopped straw and dry grasses are mostly used for padding.
The fruits should be cleaned and polished lightly with a piece of cloth, before wrapping them in
tissue paper or newspaper. Use of CFB carrions in place wooden boxes
is highly beneficial. Mandarins are generally transported by rail or road as ordinary cargos
without refrigeration, which often leads to heavy losses due to decay and fungal infection.
Storage
Green coloured fully ripe mandarins can be stored successfully at 8 -10º C with 85 – 90% RH
without impairing fruit quality. Kinnow mandarin fruit wrapped in HDPE 10G Poly bags haring
0.5% ventilation area can be safely stored up to 60 days and 80 days at ambient and cold storage
respectively without much loss of quality. In Nagpur Santra, neem leaf extract @ 20% sprayed
on fresh and fully matured fruits and packed in perforated polythene bags then stored in cool
chamber. The results indicated that after 42 days of storage a minimum PLW (18%) & rotting
(18%) Fruits (Green mature, colour break and ripe stage) dipped in 8% wax retained the
freshness of fruits up to 60-3 days under ambient condition.
Acid lime: C. aurantifolia
It is also called or sour lime. The fruit juice is rich in citric acid and ascorbic acid.
Climate and soil requirement
Tropical and subtropical. Can be grown upto 1000 m above MSL. Deep well drained
loamy soils are the best. They are sensitive to frost. The optimum temperature is 20 to 30°C.
Soil pH should be 6.5 to 7.0.
Season : December – February and June – September
Planting: Healthy seedlings may be planted during June to December at 5 to 6 m spacing in 75
cm [3] pits.
Irrigation : Irrigated copiously after planting. After establishment, irrigation may be given at 7
10 days interval. Avoid water stagnation.
Manures and fertilizers per plant
N to be applied in two doses during March and October. FYM, P2O5 and K2O are to be
| applied in October. | Col2 | Col3 | th |
|---|---|---|---|
| Manures and fertilizers |
1 year (kg) | Annual income (kg) |
From 6th year (kg) |
| FYM | 10.00 | 5.00 | 30.00 |
| N | 0.200 | 0.100 | 0.600 |
| P | 0.100 | 0.025 | 0.200 |
| K | 0.100 | 0.040 | 0.300 |
Spray zinc sulphate at the rate of 0.5% (500 g/ 100 lit of water) thrice in a year (March,
July and October) after the emergence of new flushes.
After cultivation
Remove branches of main stem upto 45 cm from ground level. Application of green
leaves 30 kg per tree once in 3 months.
Intercropping
Legumes and vegetable crops can be raised during prebearing age.
Growth regulator
To increase fruit set spraying 2,4-D-20 ppm during flowering. Fruit retention spraying
2,4-D@ 20 ppm or NAA 30 ppm after fruit set (marble size).
Summary Cheat Sheet
| Topic | Key Point |
|---|---|
| Citrus group | Includes orange, lemon, lime, pummelo, and grapefruit types. |
| Taxonomy | Citrus belongs to family Rutaceae with diverse cultivated species. |
| Establishment | Proper planting season, spacing, and pit filling determine orchard success. |
| Crop care | Balanced nutrient and irrigation management supports fruit set and retention. |
| Hormonal support | Regulator sprays may improve set and retention at critical stages. |
References
2 sources • [1] [2]
References
Class notes: HORT 181 - Citrus classification and cultivation
Citrus management schedules (as cited in lesson text)
Lesson Doubts
Ask questions, get expert answers