- (((AGRO CLIMATIC REQURIMENTS)))
Mandarins grow successfully in all frost free tropical and sub-tropical regions upto 1,500 m. above m.s.l. An annual rainfall of 100-120 cm. and temperature ranging from 100-350 C is suitable for cultivation of the crop. Mandarins can be grown in a wide variety of soils but medium or light loamy soils with slightly heavy sub-soil, well-drained with pH of 6.0-8.0 are ideal for cultivation.
- ((( GROWING & POTENTIAL BELTS)))
Nagpur santra (mandarin) is chiefly grown in Satpura hills (Vidharba region) of Central India, hilly slopes of Darjeeling (West Bengal) and Coorg (Karnataka). In South India, Wynad, Nilgiri, Palney and Shevroy hills are the major mandarin growing belts while hills of Meghalaya (Khasi, Dusha, Garo, Jaintia), Mizoram, Tripura, Sikkim and Arunachal Pradesh have predominance in mandarins. In Assam, Brahmaputra valley and Dibrugarh districts are famous for mandarin production.
The state-wise growing belts are given in the following :
State Growing and Potentials belts
Maharashtra- Nagpur, Akola, Amravati, Wardha
Rajasthan- Jhalawad, Kota
Karnataka- Chikmagalore, Kodagu, Hassan, Bijapur, Gulbarga, Bagalkot
Madhya Pradesh- Chhindwara, Mandsaur, Betul, Ujjain, Shajapur, Khandwa, Khargone, Dhar, Ratlam
Assam- Tinsukia, NC Hills, Karbi Anglong, Kamrup, Goalpara, Dhemaji, Jorhat
Nagaland- Wokha, Tuensang
Tamil Nadu- Dindigul, Salem, Nilgiris
West Bengal- Darjeeling
Orissa- Gajapati, Ganjam, Keonjhar, Kalahandi, Phulbani, Mayurbhanj, Sundergarh, Bargarh, Sambalpur
Meghalaya- East & West Khasi, Ri-Bhoi, Garo hills, Jaintia hills
Important mandarin orange varieties cultivated in India are Ngapur Santra, Coorg Santra, Khasi Santra, Mudkhed, Shringar, Butwal, Dancy, Kara (Abohar), SZ-IN-COM, Darjeeling Mandarin, Sumithra mandarin, Seedless-182 and Kinnow mandarin.
- ((( LAND PREPARATION & PLANTING)))
Land is prepared by ploughing, levelling and removing weeds.
(( Planting Material))
Mandarin orange is propagated by seeds and also vegetatively propagated by T-budding.
(( Planting season))
Seedlings are mostly transplanted in the month of July-August after commencement of monsoon. Budding should preferably be done in last week of January or first week of February following the ‘T’ or shield budding method.
Mandarins are usually planted in pits of 50 cm. X 50 cm. X 50 cm. size in a square system with a spacing of 4.5-6 m. , accommodating 350-450 plants/ha. In north-eastern parts of India, Khasi mandarins are very closely spaced (4.5 m. X 4.5 m.), accommodating more than 500 plants/ha. However, a spacing of 6 m. x 6 m. accommodating 120 plants/acre has been considered for the present model.
The recommended fertilizer dose interms of N, P & K is given in the following table : Age of the plant- [Year-wise fertilizer applied (g./plant)] N, P, K, 1- 150, 50, 25, 2- 300, 100, 50, 3- 450, 150, 75, 4 & above- 600, 200, 100, About one third of the recommended dose of nitrogen should be applied through organic manures like FYM, cakes etc. In case of non-bearing trees, nitrogen should be applied in split doses during April, August and November; phosphorus in August and November and potassium in November. Nitrogen should be applied in three split doses in case of bearing trees during April, August and November along with 200 g. phosphorus in two split doses in August and November and 100 g. potassium in November for mandarin grown in black clay soil.
Micro-nutrients viz. zinc, copper, manganese, iron, boron and molybdenum are required in ample quantities. Improper supply of nutrients may cause serious disorders which may lead to decline of the whole orchard. The micro-nutrients should be supplied through foliar spraying.
Irrigation is provided at an interval of 10-15 days during winter months whereas during summer months it is provided at an interval of 5-7 days.
Water requirement of citrus trees is generally higher than most of the other sub-tropical fruits due to recurrent growth and development. The water requirement varies from 900 to 1100 mm. per year depending upon the location. Water requirement of young (1-4 years old), middle (5-8 years old) and mature (9 and more) Nagpur mandarin trees varies from 5 to 15 litres/day, 35 to 105 litres/day and 60 to 170 litres/day respectively.
((Advantages of drip irrigation))
Drip irrigation leads to effective, efficient and economic use of irrigation water and is recommended specially in low rainfall regions of Maharashtra, MP and Rajasthan which are some of the major producing areas.
The advantages of using this technology are :
- Irrigation is controlled as per requirement of evapotranspiration needs.
- Water is applied directly to the root region of the crop.
- Improvement in plant growth , yield and quality.
- High efficiency in water application and use.
- Water saved compared to flood irrigation is 50-60%
. • High fertilizer use efficiency.
- Conservation of soil, water and nutrients.
- Land leveling work is minimized.
- Minimum incidence of insect, pest and disease.
- Continuous cultural operations are possible.
- Weed infestation is reduced.
- Minimum labour requirement.
- (((TRAINING & PRUINING)))
Trees are trained to single stem with 4-6 well-spaced branches for making the basic framework. The lowermost branches are not allowed to grow below the height of 50 cm. from the soil surface. Pruning is done during the initial years of planting. The bearing trees require little or no pruning. Main objective of pruning the bearing trees is to maintain the framework and to secure higher yields with better quality fruits. Pruning of bearing trees though differs with variety but chiefly consists of removal of dead, diseased, criss-crossed and weak branches. Removal of water sprouts 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.
Pre-emergence herbicides (Diuron @ 3 kg./ha. or Simazine @ 4 kg./ha.) should be sprayed twice at an interval of 120 days from the last week of May for effective and economical control of dicot and monocot weeds in the orchard.
Application of dry leaf mulch or paddy husk to a thickness of about 8 cm. in the basin keeps down the weed growth and decreases the number of irrigations and also improves fruit quality.
Intercrops viz. pea, cowpea and gram can be taken in mandarin orchards.
- (((GROWTH REGULATORS)))
Fruit drop in mandarin orange can be controlled in early stages of fruit development by applying two sprays of growth regulators- 2,4 D (15 ppm.) or GA3 (15 ppm) alongwith Benomyl (1000 ppm.) and urea (1%) after fruit set at monthly interval in May and June. The same spray schedule may be followed in September and October in order to control the pre-harvest fruit drop.
(( Crop Regulation))
In south and central India, mandarins bloom thrice a year. February flowering is known as ambe bahar; June flowering as mrig bahar and October flowering as hast bahar. In order to get fruitful yield in any of the three flowering seasons, resting or root exposure or bahar treatment is given in the Deccan region. In this method, roots of the plant are exposed to sun by removing upto 7-10 cm. soil around 40-60 cm. radius of tree trunk.
The water is withheld for about a month 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 farmyard manure 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 defoliation of trees.It depends upon the choice of the grower as to which of the three 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’ so that the plants are forced to rest in April-May and no water is required during the period. Plants put forth new vegetative growth, followed by flowering (July-August) and fruiting during the coming season. Resting treatment is not feasible in north India, as mandarin plants normally rest in winter and flower once a year.
- (((PLANT PROTECTION)))
Devitalization of plants due to poor fruit set, fruit drop both at bearing and maturity stage, stem tunnelling, bark removal, girdling etc., on account of the attack of the different insect pests viz. citrus black fly, citrus psylla, citrus leaf miner, bark eating caterpillar, mealy bugs, citrus aphids, citrus thrips, fruit fly, mites etc. results in poor performance by the tree in terms of quality fruit production. Spraying with insecticides viz. monocrotophos, phosalone, dimethoate, phosphamidon, quinalphos etc. depending upon the type of pest infestation has been found to be effective in most cases.
The main diseases reported are twig blight, gummosis, damping off, root and collar rot. The affected plants should be sprayed with Ridomil MZ 72, Bavistin, Benomyl etc. depending on the type of infection.
- (((HARVESTING & YIELD)))
Fruits are harvested when they attain full size, develop attractive color with optimum sugar and acid blend. Fruits should be harvested preferably with clipper, shears or secateurs. Mandarins should not be harvested in wet weather or during rains. Mandarins start bearing from the fourth year but substantial yield can be expected only from sixth year onwards. Mandarin produces 500-800 fruits after about 9-10 years. However, its plants attain the level of full bearing at the age of 10-12 years.
The net productive life span of mandarin orchards after deducting the first 5 pre bearing years is only 15-20 years. Degreening of mandarins by applying ethrel (50 ppm.) one week before the actual date of harvesting has become a commercial practice in most of the developed mandarin growing countries. Further, fruits dipped in 50 ppm. ethrel after harvesting develop golden yellow color within 5 days of the treatment. Average yield is 4.8 tonnes/acre.
- (((POST HARVEST MANAGEMENT)))
Fruits are graded on the basis of their size and color. The fruits which are oblong, high collard, immature, puffy, blemished, deformed, deep green colored, bruised and diseased are removed during the sorting operation.
Green or fully ripe fruits can be stored in evaporative cool chamber at 8-100C & 90-95% relative humidity for a period of three weeks after post-harvest treatment with Bavistin (1000 ppm.). Yellowish green fruits develop attractive yellowish orange in this chamber.
The harvested fruits are usually washed with chlorine (1000 ppm.) and after removing the surface water they are coated with stayfresh high shine wax (2.5%) containing Bavistin (4000 ppm.) and finally dried at 500-550C in the tunnel dryer. 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 grass 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 ventilated corrugated fibre board cartons in place of wooden boxes is highly beneficial.
Mandarins are generally transported by rail or road as ordinary cargos without refrigeration.