Cultivation Of Citrus

By Punjab Agricultural University on 04 Feb 2016 | read
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The Citrus fruits comprising of Mandarins (mainly Kinnow), Sweet Oranges, Limes, Lemons and Grapefruit are of major economic significance in Punjab. Kinnow ranks first with respect to area and production, followed by Sweet Orange and Limes and Lemons. Thedistricts of Fazilka, Hoshiarpur, Ferozepur and Faridkot, occupy overhalf of the area under Kinnow in the State. Sweet Orange is grown particularly in the arid irrigated region of Punjab i.e. districts of Fazilka,Ferozepur, Faridkot, Mukatsar, Bathinda and Mansa. The Citrus fruits are rich source of vitamin C (25-60 mg of vitamin C per 100g of juice). The rind of fruit is rich in pectin and essential oils.

Climate and Soil

Citrus plants, being of tropical origin, cannot withstand extended cold periods. Temperatures of –2oC to OoC are injurious to the Citrus plants, if such low temperatures prevail for long periods. Extremely high temperatures are also not conducive to the production of the high quality citrus fruits. Under such conditions, the foliage is killed and much of the fruit drops. In areas, which have more total heat units available during the growing season, Oranges mature early with a higher amount of total soluble solids. Citrus fruits are successfully grown in comparatively dry areas of Punjab provided adequate irrigation facilities are available. Citrus plants can be grown almost all over the Punjab State.Citrus thrives well in deep, fertile, well-drained soils devoid of any hard pan and layer of calcium carbonate in root zone. Citrus trees are susceptible to salt injury and cannot thrive well in saline/alkaline soil. Presence of excessive free lime leads to deficiency of phosphorous, manganese, zinc and lime induces chlorosis. The soils,which are water-logged or have a high and fluctuating water-table should not be put under Citrus. Soils having electrical conductivity upto 0.5 mmhos/c m, calcium carbonate up to 5 per cent, lime concentration upto 10 per cent and pH upto 8.5 are suitable for successful cultivation of Citrus. The optimum pH range for Citrus cultivation is between 5.5 to 7.5.

Recommended Cultivars

1. Mandarins (santra)

Daisy (2013): Daisy is a cross between Fortune and Fremont mandarin. It is an early maturing variety and mature from 5th-20th November. It produces a medium-large, mid-season fruit with an attractive dark orange rind. It peels and sections moderately well.Daisy is moderately seedy with 10-15 seeds per fruit. The average fruit weight is 210 g, seed number 9, TSS 11.5%, acidity 0.54% and juice content 41.8%. The average yield is 57 kg per plant at 5th year age. Daisy is suitable for the area having soil pH less than 8.0 and raised on Carrizo root stock. Complete fruit harvesting up to 20 November.

W. Murcott (2013): The tree is moderate in size and vigor. The fruit is usually flattened with a thin, smooth, orange rind that is easy to peel. The fruit is low-seeded in the absence of cross-pollination,but seedy when cross-pollinated. The flesh is orange-colored and juicy, with a rich and sweet flavor. It is mid-season variety and mature from 1st - 20th January. Average fruit weight is 201 g, seed number 10,TSS 9.6%, acidity 0.68% and juice content 39.0%, its average yield is 57 kg per tree at 5th year age. It is suitable for the area having soil pH less than 8.0 and raised on Carrizo root stock.

Kinnow (1968) : It is a prime fruit of the State. Fruit medium globose to oblate; skin golden orange when fully mature; acidity moderate with fine sugar/acid blend; flavor very rich and seeds 12 to 25. It matures in January and can produce 125-150 Kg fruits/tree.

Local (1968) : It may be planted in some pockets of Gurdaspur,Hoshiarpur and Roopnagar districts of Punjab. Fruit small to mediumin size, oblate to subglobose; skin cadmium yellow, base short necked and furrowed; flavor fair, juice abundant, slightly acidic;seeds 3-7; matures in December-January.

2.Sweet Oranges (malta)

Valencia (1968) : Fruit medium, slightly oval; skin deep golden yellow; juice abundant, sub acid in taste, rich in flavor, seeds 2-7;ripens during February-March and produce 38.9 Kg fruit/tree.

Musambi (1962): Fruit small to medium, subglobose,surface smooth with longitudinal furrows,apex marked with circular ring, fleshpale yellow or whitish; juice has low acidity; seeds 20-25;ripens in November. The average yield is 41.3 Kg fruit/tree. Plants budded on Pectinifera root stock do better than others.

Jaffa (1962) : Fruit medium to large,round to oblate; skin or angered; acidity and sweetness well blended; flavor rich; seeds 8-10;ripens in December. The average yield per plant is 54 Kg.

Blood Red (1962) : Fruit medium to large; roundish to slightly oblong, rind thin, deep orange, tight and glossy; flesh fully red when ripe; rich flavor with sweetness and acidity well blended;seeds 8-10; ripens in December-January. Plants budded on Cleopatra root stock do better than other root stocks. The.The tree can yield 42.3Kg fruit/tree.

3. Grapefruit

Star Ruby (2009) : Trees medium in size, fruit size small to medium, shape oblate-roundish. Peel smooth, glossy yellow having distinctly bright red blush. Flesh color is deep red, fruits seedless(1-2 seeds), juicy, rich in vitamin C and have high TSS well blended with acidity. It is an early variety which ripens during last week of November and have yield of 53 kg fruit/tree.

Red Blush (1995) : Fruit small to medium, oblate, peel smooth,glossy and deep yellow having crimson color in patches at maturity.Deep bright crimson blush in juice vesicles. Mildly acidic and high in TSS, seeds 0-8, mostly aborted; ripens during last week of November.Average yield is 76.5 Kg fruit /plant.

Marsh Seedless (1968): Fruit medium to large; oblate-roundish;skin light yellow, smooth; acidity and sweetness medium; seeds none to six; ripens in December-January. The average yield of this variety is 92.8 Kg fruit/plant.

Duncan (1968): Fruit large; oblate; skin pale light yellow or creamy; acidity and sweetness good but bitterness well marked,seeds about 40-50. Ripens in January. It matures late in January and yield 84 Kg fruit/tree.

Foster (1968): Fruit medium to large; oblate; skin pale yellow,flesh pink, acidity and sweetness well-blended, bitterness well marked;seeds 40-50; ripens in November-December. It yields 51.4Kg fruit/tree.

4. Lemon

Punjab Baramasi Lemon (2008) : Tree spreading and vigorous,fruit medium to large, spherical in shape, peel smooth, fruit very juicy with low seed content and matures in the first week of July.Average yield is 84 kg fruit/plant.

Punjab Galgal (1994) : Its trees are vigorous. Fruit is medium in size, oval in shape, peel is smooth, glossy, medium thick and yellow at maturity. Its juice has 5.2 per cent acidity, and 5-8 seeds per fruit. It matures in last week of November and gives 80-100 kg fruit per tree.

PAU Baramasi Lemon-1 (1990): The fruit is lemon yellow, round,tapering towards the base and apex is rounded. The skin is smooth and thin. Fruit is very juicy and seedless and Contains about 7 per cent acidity.

Eureka (1968) : Fruit medium oblong, apex nippled; skin lemon yellow, smooth, juice abundant, clear, strongly acidic with excellent flavor; seeds rarely present ripens in August-September.

5. Lime (Nimboo)

Kagzi (1968): Fruit small, round and thin skinned, pulp greenish white, juice strongly acidic.

6. Sweet Lime (Mitha)

Local (1968): Fruit medium, globose to ellipsoid, rind smooth with distinctive aroma. Juice abundant, lacking in acidity and insipid,seeds 5-6 ripens in the beginning of September.

Propagation

The propagation of quality plants need utmost attention because of susceptibility of citrus to viruses and mutation. The quality of nursery plants has a major contribution in the productivity of Citrusorchards vis-à-vis the decline problem.

Rootstock Raising: Jatti Khatti (Rough Lemon) is best root stock for Kinnow, Jaffa, Grapefruit, Lime & Lemon where as Cleopatra for Blood red and Pectinifera for Musambi.Jatti Khatti seeds should be obtained from healthy fruits fromvigorous trees. Preferably the fruits which are too close to the ground should not be used for seed extraction for fear of Phytophthora infection. The seeds are extracted in August-September. Immerse the seeds in hot water at 52'C for about 10 minutes to check phytophthora infection. For Blood Red, the seeds of Cleopatra should be sown in the first week of February for raising the root stock seedlings. For Musambi, Pectinifera seeds should be sown during August-September to raise the root stock seedlings.Citrus seeds should be sown in nursery soon after extracting from fruits, as they loose viability rapidly. The seeds are sown in nursery beds of 2 m x 1 m size and in rows 15 cm apart. The seeds should never be sown more than 2.5 cm deep.The seedlings are transplanted to nursery field when seedlings are 10-12 cm in height. The seedlings of uniform vigor and height should be selected for transplanting. Dwarf and exceptionally vigorous seedlings and those with badly crooked roots should be removed.Discard approximately 25 per cent of total seedlings. This would ensure the uniformity of stock and selection of nucellar seedlings. At the time of transplanting, care should be taken to prevent doubling up of the roots. If necessary, the roots may be pruned back slightly before planting.Spray of 1.5% urea (15 g/liter of water) on Rough lemon seedlings at monthly interval (March to December) increases number of buddable plants, improves budding success and produces healthy Kinnow plants.

Maintenance of Mother Trees of Kinnow for EnhancedBud Wood Supply

For the induction of more bud wood required for the nursery production, the mother trees of Kinnow should be pruned at 8 feet height from ground level along with topping of side branches during last week of January to first week of February. Bordeaux paste should be applied on cuts after pruning. The fruits should also be removed from the Kinnow mother trees after fruit set in the month of April.

Budding

Pencil thickness seedlings are budded by inserting shield shaped bud into the slot cut in the bark of the seedling at 15-20 cm from the ground level. This slot is usually ‘T’-shaped. It can be made by first making a horizontal cut about 1.5-2.0 cm long according to the thickness of the stock. Another vertical cut, about 2.5 cm long, is made downwards from the middle of the horizontal cut to receive the bud shield. After the ‘T’-cut has been made in the stocks, the bud is removed from the bud stick and inserted into the slot and wrapped up with the plastic tape keeping the bud eye uncovered. The wrapping should be fairly tight, but not so tight as to girdle the stock. The sprouts of the stock seedlings below and above the bud union should be removed regularly.Shield or ‘T’-budding is done in Sweet orange, Kinnow, Grapefruit etc. during mid February-March and again during August September,when the sap flows in the seedlings. In Lemons and Limes, the plants can be propagated by air layering (gootie) or by cuttings. Moss grass or roots of water hyacinth can be used as a rooting media.The cuttings are planted in well prepared nursery beds or in polythene bags about 5x7 cm size during February or September.Care should be taken in the nursery that the attack of any insect pests and diseases should not be allowed of adopting recommended practices.

Containerized Nursery Production of Kinnow under Protected Conditions

Preparation and sterilization of potting mixture

The potting mixture consisting two parts of soil, one part of farmyard manure and one part coco peat should be prepared on a concrete floor and spread as a flat bed of 45 cm height. These beds should be drenched with water and covered with 100µ UV stabilized transparent polythene sheet during the last week of April to May for4-6 weeks. The solarized soil is further fumigated with BasamidGranular (Dazomet 98 per cent) @50 g/m2 and completely covered with 100µ UV stabilized transparent polythene sheet during MayJune.After three weeks, the polythene sheet should be removed andthe mixture should be given at least three turnings at an interval of one week to remove the fumigant.

Raising of rootstock and budding

The rough lemon seeds (2 seeds per bag) should be sown directly in black polythene bags (size 12” x 7”, 250 gauge) filled with sterilized potting mixture consisting of FYM + Soil + Cocopeat (2:1:1 v/v) inthe second fortnight of August under screen house/ polycarbonateroof screen/ shade net house.The seeds start germinating in about 3 weeks and when the seedlings become 10 cm tall retain only one nucellar seedling per bag by uprooting all other seedlings. Then the seedlings should be sprayed with 1.5% urea at monthly interval. The polythene bags containing seedlings should be shifted in glasshouse/ polyhouseduring winter (mid-November till end of February) which should again be transferred to screen house/ shade net house (50% shade) during first week of March. More than 75 per cent seedlings will become buddable in the first fortnight of May. The budding operation can be started from May on wards under shade net house which will become salable during September-October and remaining plants will become salable in next March.

This technology will help in propagating kinnow plenty in shorter possible have fulfilling the ever increasing demand for quality planting material of kinnow. It requires smaller nursery area and there is no need to change nursery site every year. It will reduce the transplanting shock and lead to higher survival, continuous and quick growth of plants in field. The containerized nursery production under protected conditions reduces the incidence of insect pest & diseases and eliminates the spread of soil borne diseases, insect and nematodes.

Planting

There are two planting seasons for Citrus plants in Punjab i.e.the spring and the monsoon. The spring planting starts from 15 th February and continues up to 15th March. The monsoon season starts from the middle of August and continues up to the end of October.Citrus is, however, commonly planted when rains have set in and the weather has sufficiently cooled down. Kinnow and Baramasi Lemon plants can be successfully transplanted bare-rooted during December February.After digging the plants from nursery, remove the one-fourth foliage and cover the rest with moist wrapping material.

Training and Pruning

Citrus trees may be pruned at any time, but it is better to avoid those periods when trees are in active growth. The best time for  running the bearing trees is after the harvest of the fruits during late winter or early spring. For getting better yield of high quality fruit,pruning of such branches is necessary to open up the tree for proper ventilation and provide more chances for inner wood to bear fruit.Removal of dead and dried wood is necessary to check the further spread of diseases.

These nutrients can also be supplied from other fertilizers available in the market (Appendix-I).In Kinnow and other citrus fruits, entire farmyard manure should be applied during December. Split the N dose into two parts and apply the first half in February and the second half in April-May after fruit set. Apply phosphorus along with the first dose of nitrogen.

Zinc and Manganese Deficiency : The symptoms of zinc deficiency appear on fully mature new leaves as irregular interveinalchlorosis commonly known as “mottled leaf”. The terminal leaves become small and narrow referred to as ‘little leaf’. Fruit bud formation is severely reduced and twigs die-back. To control zinc deficiency,spray zinc sulphate solution 0.47% (4.7 g/liter of water) without addition of lime on spring flush in end April and on late summer flush in mid August. Foliar application should be given to the fully developed flushes. To correct zinc and manganese deficiency, spray the plant with zinc sulphate (470g) + manganese sulphate (330g) in 100 liters of water in end April and mid August. A gap of one week should bekept between the foliar application of Bordeaux mixture and zincsulphate and manganese sulphate solution.

Irrigation

The young plants up to the age of 3-4 years, should be irrigated at weekly intervals, whereas, older trees be irrigated after 2-3 weeks interval, depending upon the climate, rainfall and type of soil. Irrigation is crucial before sprouting in February, after fruit set in April and in the hot weather, otherwise the growth of trees may be adversely affected resulting in the excessive shedding of flowers/fruits.

Drip irrigation in Kinnow

The drip irrigation system enables efficient and judicious use of water along with improvement in yield. The requirement of water during different months according to age of the tree is given as below :Amount of water (liter/day/plant) to be applied to Kinnow through drip irrigation Month Age of plants (Yrs)0-2 3-4 5-6 7-8 9 and more Jan 3 6 9 12 15 Feb 6 12 18 24 30 March 9 18 27 36 45 April 13 25 39 52 65 May 16 32 48 64 80 June 17 34 51 68 85 July 13 26 39 52 65 Aug 12 24 36 48 60 Sept 11 22 33 44 55 Oct 8 16 24 32 40 Nov 5 10 15 20 25 Dec 3 6 9 12 15

Note :1. Follow the instructions for use of drip irrigation system given in Appendix-II.2. Amount of irrigation water may vary by 10-15 percent depending upon the prevailing weather conditions.3. For lifting water from canal storage tank, a booster pump with solar/electric motor of 2 HP will be sufficient for 10 acre Kinnow orchard.However, for 15 and 25 acres a booster pump with electric motor of3 and 5 HP respectively, will be required for lifting water.In the beginning, 1-2 drippers per plant or tree are required which may be increased to 4-5 depending on the soil type and age of the plant or tree. For efficient use of water sub lateral loops of the drippers should be used around each plant or tree.

Intercropping

Inter cropping should not be done in bearing orchards. But inyoung and non-bearing orchards, inter cropping upto four years with leguminous crops such as Guara, Moong, Mash, Cowpea, Gram and Pea may be done. The Guara-Wheat rotation with Guara as agreen manure can be taken in Sweet Orange for 5-6 years. Sufficient space should, however, be left unsown to permit the young trees to make unrestricted growth. Recommended fertilizers should be added to meet the requirements of inter crops separately. The fruit trees and the inter crops should be provided with independent irrigation system.

Caution : Tall and exhaustive crops like Cotton, Chari, Bajra,Maize, Berseem, Bhindi and Creeper type vegetables should not be grown in the orchards.

Weed Control

Spray Glycel 41 SL (glyphosate) @ 1.6 litre/acre as post emergence(second fortnight of March) followed by Glycel 41 SL orGramaxone 24 WSC (paraquat) @ 1.2 liter/acre (second fortnight of July) in 200 liters of water.

Control of Pre-harvest Fruit Drop

For the management of fruit drop in Kinnow (Physiological and Pathological), spray the trees with Ziram 27 SC (1250 ml)+ 2, 4-D,sodium salt of horticulture grade (5gm) or Propiconazole 25 EC (500ml)+ 2,4-D (5 gm) or Bavistin 50 WP (500 gm) +2, 4,-D (5gm) in midApril,August and September and two additional sprays of Ziram 27SC (1250 ml) or Propiconazole 25 EC (500 ml) or Bavistin 50 WP(500 gm) in end July and September in 500 liters of water per acre.

Caution : Spray 20 ppm GA3 instead of 2,4-D when cotton or other broad leaf crop are cultivated in or around the orchard.

Fruit Thinning

Kinnow tends to bear too heavily in the third and fourth year of its age. Sometimes there may be 400-500 fruits on young plants of this age. Due to such a heavy load, health of plants suffers badly and some of them may even die. Thus, the fruit on young Kinnow trees must be thinned out judiciously soon after setting in May.

Quality improvement

To improve fruit size and increase yield in kinnow mandarin,three foliar sprays of potassium nitrate (1%) at the end of May, June and July should be applied.

Fruit Maturity and Harvesting

Kinnow fruits should be harvested when they have attained proper size, attractive color and acceptable total soluble solids : acid ratio The fruit from the periphery should be picked when they attain TSS/acid ratio of 12:1, whereas the fruits from the interior of the trees can be harvested somewhat later when they have a ratio of 14:1. The best time for picking Kinnow fruits is from mid-January to mid-February with a little variation depending upon locality, season, etc.The fruits should not be pulled from the branches during harvesting as the skin from stem end can be ruptured. Harvest with the clipper retaining a non-protruding short fruit stalk (button).

Post-harvest Handling and Marketing

After harvesting, the fruit should be properly cleaned and suitably graded. The fruits can be packed in boxes in 3 or 4 layers in such away that they do not get pressed while in transit.The proper stage of maturity is the prime factor for harvesting Kinnow fruit for storage. Fruits harvested too early or late in the season do not keep well in the storage. Harvesting during early hours of the day when there is dew on fruits or immediately after rains should be avoided. Fruit spoilage can be reduced by dipping Kinnowfruits in 125 ppm Ben late for one minute, drying them in air followed by wrapping in 100 gauge perforated polythene bags.After harvested, the Kinnow fruits should be washed in cleanwater followed by dip in 0.01% chlorinated water (Sodium hypochlorite4% @ 2.5 ml/liter water). The fruits should be partially dried under shade and Citrashine wax should be applied with foam. Waxed fruits should be again dried under shade before packing. The shelf life of harvested Kinnow fruit can also be increased by the use of shrink film. After washing with 0.01% chlorinated water, the Kinnow fruits are surface dried under shade, packed in paper moulded trays followed by wrapping with shrink film (15µ). These techniques help in improving the appearance and maintain the fruit quality during marketing up to two weeks. This technique helps in improving the appearance and maintains the fruit quality during transit, storage and marketing for two weeks. The healthy unbruised Kinnow harvested during first week of February can be stored for 8 weeks at prevailing room temperature by individually seal packing with electric sealer or rubber band in 10 micron thick high density polythene bags.The Kinnow fruits harvested at optimum maturity, packed in ventilated corrugated fiber board boxes should be stored at 5-6'C and 90-95% RH. The quality remains acceptable for 45 days.

Larger sized Marsh Seedless Grapefruits can be stored better than the small sized fruits at room temperature. These can be stored for 60 days at 15-20'C. Treatment of harvested fruits with GA3 @ 30ppm and wrapping in polythene (100 gauge) considerably improve the storage life. For preparing 30 ppm GA3, dissolve 1.5 g GA3 in a small quantity of ethyl alcohol (30-50 ml) and make up volume to 50 liters with water.The non-alcoholic naturally carbonated lemon beverage can be shelf stabilized with optimized concentration of clarifying agents and optimized heat treatment with a shelf life of four months.

Citrus Decline

It may be due to several causes, such as unhealthy planting material carrying viruses and similar diseases, improper root stock,defective soil, poor drainage, mismanagement of the orchard,malnutrition, insects, nematodes and diseases.

For the Rejuvenation of Declining Citrus Orchards, the following Schedule is Recommended:

(1) Remove dead wood during January-February before the new growth starts. Spray 2:2:250 Bordeaux mixture (see chapter-I)immediately and apply Bordeaux paste to the cut surface and the trunk of the trees. Apply Bordeaux paint to the trunk after a week.The methods of preparing Bordeaux mixture, paste and paint are given at the end of the fruit portion.(2) Add fertilizers, as recommended under ‘Manures and Fertilizers’.(3) Spray 2.4 kg of zinc sulphate in 500 liters of water after one week of Bordeaux mixture in end April and mid August or on new growth flushes when the leaves have attained two-third of their size.(4) Follow the recommended spray schedule.

 

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