Course: B.Sc. Agriculture

Subject: Principles of Horticulture

Unit :4

Cultivation practices of Citrus

India ranks sixth in the production of citrus fruit in the world.

Other major citrus producing countries are Spain, USA, Israel, Morocco, South Africa, Japan, Brazil, Turkey and Cuba.

It occupies third position after mango and banana in the production of fruits in India. Citrus fruits originated in the tropical and sub tropical regions of South East Asia , particularly India and China.

North East India is the native place of many citrus species.

It is of particular interest because of its high content of

vitamin C and refreshing juice

IntroductIon of cItrus

BOTANICAL CLASSIFICATION OF CITRUS

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The 5 commercially important citrus fruit crops :

1.Sweet orange- C.sinensis 2.Tangerine- C.reticulata 3.Grapefruit- C.paradisii 4.Lemon – C.limon 5.Lime- C.aurantifolia

And minor cultivars are:6. Pumelo – Citrus maxima

7. Citron – Citrus medica

Citrange (trifoliate orange x sweet orange)

Citrumelo (trifoliate orange x grapefruit)

Tangor (sweet orange x tangerine)

Tangelo (tangerine x grapefruit)

hybrIds

Sweet orange

Grapefruit

Tangerine

Lemon

Lime

Water (%) 88 90 87 90 86

Protein (%)

44 40 44 27 37

Fat (%) 0.75 0.45 0.8 1.1 0.1

Carbohydrates (%)

0.2 0.1 0.3 0.3 0.3

Crude Fiber (%)

10.3 9.5 10.5 8.2 12.3

Nutrition in different citrus fruits

Sweet orange

Grapefruit

Tangerine

Lemon Lime

Vitamin A 4.0 0.2 1.9 <1.0 <1.0

Thamin,B1

6.4 2.8 5.6 2.9 3.1

Riboflavin,B2 1.9 1.2 1.7 1.2 1.1

Niacin 2.2 1.1 1.6 0.5 1.1

Vitamin C 109 84 76 118 88

Calcium 1.2 1.1 4.5 3.2 2.4

Phosphorus 2.1 1.9 2.2 2.0 1.9

Iron 2.5 2.0 4.0 6.0 2.6

Sodium --- --- --- --- ---

Potassium 4.2 3.4 2.3 2.9 2.1

BENEFITS AND USES OF CITRUS

Contains high amount of flavonoid, it helps to improve the immune system fighting against forming of free radical causes of tumour and cancer.

Strengthens the small blood vessels, protects against Rheumatoid arthritis and reduces the risk of cell membranes being damage caused the forming of free radical due to high amount of vitamin C.

Reduces the risk of heart diseases and stroke as it lowers the bad cholesterol.

Benefits:

Citrus peels are rich in pectin, valuable in making jellies, marmalades, candies, jams and pharmaceutical preparations

• Citrus trees are subtropical in origin and cannot tolerate severe frosts.

• Moisture is also a limiting factor in citrus production, When rainfall is poorly distributed and, it is necessary to supplement moisture by irrigation to ensure that moisture stress do not suppress growth and production.

• Citrus (except lemons) require shorter days and cooler temperatures in winter for a normal production rhythm.

• Flowering should occur almost exclusively in spring, and these spring flowers should produce a large fruit crop 7 to 12 months later, depending on the cultivar

CLIMATIC REQUIREMENTS

Citrus trees grow in almost any soil that is well-drained, sufficiently aerated and allows tap root to penetrate to the desired depth.

Citrus can be grown in a wide range of soil types provided they are well drained. Fertile, well-aerated soils with a pH of between 6 and 6.5 are ideal.

The growth, development and production of a plant depend on the physical characteristics of the soil such as drainage, density, texture, water-holding capacity, structure, soil depth, the homogeneity of the profile, erodibility, and the degree to which water can infiltrate the soil. These characteristics differ in the various soil types.

Classification and VarietiesSweet Orange

Mandarin Oranges

Grapefruit Lime

Pummelo

Lemon

Citron2

Sweet orangesBotanical name - Citrus sinensis Osbeck

cultivars of sweet orange four groups: (i) Spanish oranges

(ii) Mediterranean oranges

(iii) Blood oranges and

(iv) Naval oranges.

Spanish Orange

Mediterranean Orange

Mediterranean Orange

Naval Orange

SW

EET O

RA

NG

E

3

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The most important cultivars of sweet oranges, cultivated on a commercial scale in India areMalta, Blood Red and Pineapple in Punjab

Mosambi in western India

Sathgudi and Batavian in South India.

Valencia Late and Washington Navel oranges are also important varieties of sweet oranges

Mandarin Oranges

Botanical name — Citrus reticulata B. Loose-skinned oranges are commonly

designated as mandarins. Small tree 2-8m in height. leaves small,Ovate, narrow, elliptical or

lanceolate usually crenate. flowers white. fruits depressed-globose, 5-8 cm in diameter,

contains tangererine as prominent glucoside. Pulp sweet and juicy, orange in colour, seeds

polyembryonic.

C. reticulata - Tangerine, mandarin, or satsuma C. unshiu (Satsuma)

C. deliciosa (Willowleaf)

C. reshni (Cleopatra)

C. nobilis (King)

C. temple (Temple)

Mandarins or Tangerine

GrapefruitBotanical name- Citrus paradise Macf.

Grape fruits are closely related to Pummelo.

It is used as a breakfast fruit, the juice has a characteristic

flavour with wild bitterness.

The plants are spreading with a length of 10-15 m, Petioles

broadly winged. Flowers axillaries- single or in clusters, 4-5

cm. in diameter, petals white,

Fruit large, 8-25 cm. in diameter, greenish or pale yellow

when ripe, rind thinner and pulp vesicles smaller than

Most widely planted cultivar is Marsh (Marsh Seedless) with

only 4-8 seeds per fruit. Thompson (Pink Marsh) has pink

flesh and 0.5 seeds per fruit. It is a bud mutant. Bud

mutations of ‘Thompson’ are 'Ruby' and 'Webb'. The

interspecific hybrid and C. reticulata is known as Tangelos

Lime The lime are represented by Mexican group, Tahiti group and mandarin limes.

Acid lime - C. aurantifolia Swingle. Acid lime is the most important acid fruit of tropics. It is the tenderest of all the citrus fruits. Tahiti (Persian) Lime - (C. latifolia Tanaka). This group differs in many characters from the true limes of the Mexican group. The trees are larger, more spreading and cold-resistant, nearly thorn less.

Rangpur lime (C. limonia Osbeck)- Rangpur lime is indigenous to India and commonly grown for rootstock purpose.

Sweet lime- (C. limetoides Tanaka)- They are similar to Tahiti limes, but sweet.

Pummelo- Citrus grandis L

It is a valuable root stock for dry lands. The fruit may be used in making marmalade. The trees are spiny, spreading 5-15 m. in height.

Leaves large, petioles broadly winged, flowers large, borne single or in clusters, petals cream coloured, stamen, 20-25 Fruit very large globose or pear shaped, 10-30 cm. in diameter, thick peel, pale yellow or pink with sweetish juice, mono embryonic seeds.

Important cultivars are Walter, Chakaya, Large red

fleshed. Large white fleshed and Gill's Jeolikote

Lemon (C. limon Burm)

Varieties are classed on the basis of fruit and tree characters into 4 groups

(i)Eureka group

(ii) Lisbon group

(iii) Anomalous group and

(iv) Sweet lemon

(i)Eureka lemon

(•) The trees of Eureka lemon are medium size, spreading, open, almost thorn less.

(•) The Eureka is a heavy yielder and begin early in age.

(•) The fruits normally mature from August onwards in the Punjab.

(ii) Lisbon lemon –• Large and vigorous trees, spreading,shoot upright,

numerous, medium thorny.• Fruit colour lemon yellow, surface smooth, shape

ellipsoid to oblong, size medium.• Pulp fine-grained, pale greenish-yellow, juice

abundant, clear, very acid quality excellent seed number 0-10.

(iii)Lucknow seedless-- It has medium size trees, hardy, vigorous spreading

and dropping almost to the ground with an irregular crown.

- . Fruit oblong lemon, yellow, smooth, base rounded, rind thin, axis hollow, segments 10-13, pulp light yellow and coarse, juicy,

- The fruit ripens mainly from November to January.

(iv)Hill lemon (Galgal)- C. pseudolimon Tanaka- It has tall, hardy, vigorous, upright and

spreading trees with an irregular and loose crown.

- The fruits ripen form October to December

Citron (Citrus medica L.)

Citron is raised by seeds and stem cutting is Uttar Pradesh, Punjab.

Citron is used as medicine and ornamental purpose. 3 m high shrubs or small trees with stout spines. Leaves elliptical, serrate, petiole short wingless and not

articulated with lamina Inflorescence raceme, 5 petioles tinged pink, stamens 30-40. Fruits large, oblong, 10-20 cm long, peel usually bumpy, yellow, very thick having sour taste.

Citrus propagationIn India citrus trees are propagated both by seeds and vegetative means.

Seed propagation is still practiced in the case of acid limes and to produce rootstocks for budding purposes. It produce true to type seedlings i.e. polyembroynic seedlings.

Shield or T budding is the most commonly used method of vegetative propagation. Budding is generally done either in spring or in September

Raising of seedling Freshly extracted seeds are sown on well prepared

nursery bed at the distance of 20 x l0 cm and 1.5 to2cm deep.

Germination completes within 3 weeks. The apogamic seedlings are identical to the parent in

growth and production. Seedlings are ready for transplanting 6 to 9 months

after sowing. Seeds are sown in seedbed during July- August.

Rootstock characters:

Must be compatible with the scion variety allowing good growth, long life, good yield and good fruit qualities.

Seeds must be readily available, preferably high poly-embryonic to get uniform seedlings and with high percentage and germination.

Must be adaptable to a wide range of soil depth, texture, structure, pH, salinity, moisture, and nutrient supply.

Must be resistant to soil-borne diseases, such as Phytophthora grimmosis.

Rootstock Characters

Rough lemon Suitable for light (sandy) and infertile soil, resistant to Tristeza virus. But it is most susceptible to cold and induces poor quality fruit

Sour orange Suitable for silty, clayey and poorly aerated soils , improves the fruit quality and has high sugar and acid content, improve the fruit size

Cleopatra mandarin

Suitable for heavy soils

Trifoliate orange

Cold tolerant, improves the fruit quality and has High sugar and acid content, hasten fruit maturity and the fruit size. It also induces precocity. Resistant to Citrus nematode (Tylenchulus semipenetrans). It is ideal for high density plantations

Sweet lime It gives high yield in early age followed by reduction in the yield later on. Also it is most susceptible to cold and induce poor fruit quality

Sour lime Most susceptible to cold

Rootstock Characters

Rough lemon (Jambheri)

Vigorous rootstock. Induce poor fruit quality and resistant to Tristeza virus and drought and salt tolerant

Sweet lime Give high yield in early age followed by reduction in the yield

Citranges Resistant to Citrus nematode (Tylenchulus semipenetrans)

Rangpur lime Tolerant to Phytophthora foot rot and resistant to Tristeza virus , Drought and salt tolerant

Sweet orange Resistant to Tristeza virus

shield or t BuddingIn this method of propagation, a bud from desired variety (scion) is transferred on the rootstock .

with an objective of utilizing the vigorous root system of the rootstock and combining the best characters of both.

A plump, but not too elongated bud is selected from the middle section of the scion shoot.

It is removed by making an incision around the bud with the help of sharp budding knife.

On the selected rootstock T-shaped incision is made just enough to accommodate the bud.

The bud is inserted in the incision and tied with a strip of plastic film in such a way that the tip of the eye remains open. Budding should be preferably done as low as possible on the rootstock

Bud wood should be taken from parent trees which:

Hold a record satisfactory production over a period of a t least 5 years

Are free from systematic diseases

Have true-type fruit characters.

Lay-out of citrus orchards

Before planting an orchard it is advisable to provide irrigation facilities such as pipelines or concrete canals. At present the dragline sprinkler irrigation system and the basin system for flood irrigation are regarded as the most suitable for citrus orchards.The square and rectangular planting systems applicable to citrus orchards with the exception of the square system which is preferable where sprinkler irrigation is used, the rectangular system is at present favored above other systems because the smaller planting distance in the tree rows increases the number of trees per hectare.

Plant density

a. Orange: Normal spacing - 6 m x 6 m Plant population - 275 / hab. Sweet Lime :Normal spacing - 5 m x 5 m Plant population - 400 /hac. Lime/LemonNormal spacing - 4.5 m x 4.5 m Plant population - 494 / ha

In very light soils, spacing may be 4 m x 4 m. In fertile soils and in high rainfall areas spacing may be 5 m x 5m.

pruning: Pruning means removing diseased and

dead twigs, branches, and leaves which are unproductive and are less exposed to sunlight.

Best time for pruning is during the dry season or after harvest

IrrigationDuring the first 6 months the trees should be irrigated twice a week and thereafter every 7 days. The irrigation basin should be gradually enlarged as the tree grows, so that it is always slightly bigger than the drip line of the tree. Be careful not to damage the fine superficial feeder roots. The water required depends on weather conditions. Saturated and poorly-drained conditions could result in root rot, which will shorten the life of the trees. A lack of moisture during October to January could result in acid fruit. If a sprinkler is used, about 30 mm of water must be applied every 7 days, depending on the weather.

Plants need 2 – 3 fertilizer applications each year.•First, when the rainy season begins.•Second, during the middle of the rainy season. •Third, when the rainy season is about to end.• Fertilizer can be applied or sprayed.

NUTRIENT MANAGEMENT

Dose Per Plant after 5th year onwards in 2 splits

FYM N P2O5 K2O

50 kg 900 g 750 g 500 g

split Time Manures &fertilizers

1st Aug- sept FYM+1/2 N,Full P+1/2 k

2nd March-April 1/2N+1/2K

Harvesting and Yield

Harvesting –

• The fruits mature in six months after flowering.• In Gujarat, about 60 per cent of the total crop is harvested during July to

September, 30 percent from October to January and 10 percent from February to May.

• In north India, the main harvesting seasons in the months of August-September.

• Greenish yellow fruits picked by hook.• 6-8 pickings/season

Yield -• 1000 to1200 fruits & maximum 3000-6000

fruits. • (40-70 kg) per tree. Packed in gunny bagsOr trys

Fruiting :

• Flowers throughout the year after 4th year.

• Fruit takes 6 months to mature.• 60 % in July-Sept. 30 % in Oct.-Jan. & 10

% in summer

Citrus thrips Thrips nilgiriensis

Symptom of damage :

Nymphs and adults lacerate the leaf tissue and suck the sap from fruits

Leaf curling Ring like appearance on the fruit Irregular mottled patches on rind

Management:

Collect and destroy the damaged plant parts. Spraying with systemic insecticides at flush growth periods Spray malathion 0.05% or monocrotophos 0.036% or carbaryl

0.1% . Encourage the activities natural enemies such as Syrphids and

Chrysopid.

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Scales damage on citrusScale: Icerya purchasi

Symptoms of damage

Nymphs and adults suck the sap from leaves.

Honey dew excretion Development of sooty mould fungus.

Management:Spray dormant oil in late winter .Apply mixture of manure compost tea, molasses, citrus oil.Garlic-pepper tea also helps.Natural predators usually keep this insect in check.Control ants and dust which can give the scale a competitive advantage.Field release of vedalia and Australian ladybugs.

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Citrus leaf minor Citrus leaf miner, Phyllocnistic citrella

Symptom of damage Making silvery appearance presence on the lower

surface of leaves. Leaves – distorted and crinkled. Severe attack caused defoliation.

Management Spraying of monocrotophos [Nuvacron] 1.5ml,

fenvalerate 0.2ml or dimethoate [Rogor] 2ml mixed in a litre of water at weekly intervals at the time of emergence of new flush.

Spray application of NSKE 5%

Citrus fruit suCking mothFruit sucking moth:Otheris materna

Symptom of damage:Adult pierce the fruit and suck the juice Rottening at the feeding siteFruit droppingManagement:

Destroy the weed host Tinospora cardifolia and coccules pendulesBag the fruit with polythene bag (500 gauge)Apply smoke to prevent adult mothTrap crop – growing tomato crop in orchards to attract the adult mothPoison baitdilute suspension of fermented molasses and malathion 0.05% (50 EC at 1ml/lit)Use light trap or food lure to attract moths.

Tristeza Virus DiseaseThe aphid (Toxoptera citricida) transmits Tristeza virus disease. The symptoms begin with the die backof small branches and twigs, yellowing of leaves and heavy bearing small fruits. Tristeza isalso called a quick decline disease.

Control : The best method to check this disease is to control the aphid population by application of insecticides in the nursery and also in plantations.

Citrus ExocortisExocortis is characterized by drying narrow strips of outerbark, which tend to separate from the innerlive-bark. The outer bark slowly peels off as it withers. The affected trees show lack of vigour resultingin dwarfing.

Control : The disease can be prevented by the use of virus-free budwood. Grafting tools should be disinfected after pruning branches from diseased trees.

Citrus scab diseaseScab (Elsinoe fawcetti) The lesions in early stages appear on the

underside of the leaves as small semi-translucent dots.

In later stages, leaves often become distorted, wrinkled, stunted and deformed. On the fruit, lesions consist of corky projections,

which often break into scabs.

Control : The diseased leaves, twigs and fruits should be collected and destroyed. Spraying of Bordeaux mixture or Blitox (0.3%) is quite effective

Citrus Canker Citrus Canker (Xanthomonas citri) It is the most serious bacterial disease . The disease symptoms appear on leaves, branches and fruit stalks. Canker lesions appear as yellowish spots, surrounded

by acharacteristic yellow halo. The market value of the canker-affected fruits is very much

reduced

control:Three sprays of Streptocycline 100 ppm (10 g of Streptocycline + 5 g Copper Sulphate in 100 litres water) or Blitox (0.3%) or neem cake suspension (1 kg in 20 litres water) during February, October and December can control the disease.

Citrus fruit drop The causes attributed to fruit drop in citrus are lack of

fertilization, mechanical shock, insects, disease, high temperature, rainfall, and defective irrational

practices.

The most pronounced stages of fruit drop occurs when the fruits are at marble stage.

On the onset of hot summer weather during May-June the second wave of intense fruit drop occurs while pre-harvest drop occurs during ripening period, which lasts from August-January.

Image References:1. http://

www.danish-schnapps-recipes.com/images/lime-tree-with-ripe-limes-200.jpg2. http://www.speciale.it/images/Untitled-1ok.jpg 3.http://upload.wikimedia.org/wikipedia/commons/thumb/0/06/

Blood_orange_sliced.jpg/120px-Blood_orange_sliced.jpg4.http://www.nikel.com.hr/upload/tbl_proizvodi

/naranca_slatka_citrus_aurantium_dulcis_15419.jpg5. https://cdn.thewatershed.com/wp-content/uploads/2012/05/TangeloBelief.jpg6. http://media-1.web.britannica.com/eb-media/45/10245-004-60A3221B.jpg7. http://www.krishisewa.com/cms/images/articles/2013/citrus_ip13.jpg8. http://www.krishisewa.com/cms/images/articles/2013/citrus_ip11.jpg

Web Refernces:1. https://www.nabard.org/english/plant_citrus.aspx2. www. Agri info.in3. megapib.nic.in/ppcitrus.htm