Everything you need to learn about cultivating mandarins organically. Learn about:- 1. Introduction to Mandarins Fruits 2. Climate and Soil Required for Mandarins Cultivation 3. Methods of Irrigation 4. Training Pruning and Canopy Management 5. Nutrient Management 6. Selection of Crop and Induction 7. Decline 8. Yield and Harvesting Time 9. Varieties.
Contents:
- Introduction to Mandarins Fruits
- Climate and Soil Required for Mandarins Cultivation
- Methods of Irrigation for Mandarins Cultivation
- Training Pruning and Canopy Management of Mandarins Plant
- Nutrient Management of Mandarins
- Selection of Crop and Induction of Mandarins Flowering
- Decline in Mandarins
- Yield and Harvesting Time of Mandarins
- Varieties of Mandarins
1. Introduction to Mandarins Fruits:
Mandarins (Citrus reticulata) are loose skinned oranges and are cultivated in an area of 3,11,200 hectares with the combined production of all types of mandarins like Nagpur, Kinnow, Khasi, Coorg, etc. at around 29,06,300 tons (2012-13). Nagpur mandarin is cultivated in an estimated area of 1, 85,200 hectares in the state of Maharashtra (Nagpur, Amravati districts), Madhya Pradesh (Chhindwara, Mandsaur, Sehjapur) and Rajasthan (Jhalawar).
Kinnow is cultivated in an area of 82,000 hectares in Punjab (Ferozpur, Muktsar, Bathinda and Hoshiarpur), Rajasthan (Sriganganagar, Hanumangarh) and Haryana (Sirsa, Fatehabad and Hisar). Khasi mandarin is cultivated in approx. 40,000 hectares in the states of Assam, Meghalaya, Manipur, Tripura and Nagaland.
Coorg mandarin is cultivated only in 3200 hectares in Kodagu, Hassan and Chikballapur districts of Karnataka state. Whereas estimated area for Sikkim and Darjeeling mandarins is 5000-6000 hectares each.
2. Climate and Soil Required for Mandarins Cultivation:
Mandarins grow successfully in all frost free subtropical and tropical regions of the country. They are well adapted to sub-mountainous tracts and a temperature between 10-35°C is most favourable. The climate around Nagpur and also in north-east as well as in parts of Punjab, Haryana and Rajasthan favours the production of excellent quality fruits.
Nagpur mandarin cultivation is best suited to uniform, deep loamy and well drained soils. It can also be grown in shallow soils where drainage is not a problem. In deep black cotton soil of Nagpur and Amravati districts, the clay content should not exceed more than 40-50% especially after one feet depth and CaCO3 content should not be more than 5%. Kinnow also prefers deep well drained sandy loam soil. Soil pH should not exceed 8.0, EC 0.5 m mhos/cm and CaCO3 not more than 5%. Underground water should not be saline.
Soil of N.E region, particularly in Assam are sandy loam to clay loam with a pH of 4.5 to 6.0. In hilly areas of north-east region, soils are lateritic and red loams. Similarly in Kodagu district of Karnataka, soils range from red lateritic loam to medium clay loam to black clay soils with a pH of 5.0 to 6.5.
In Darjeeling area, where mandarin is cultivated soils vary from loamy to clay loam and are mostly acidic in nature. Before installation of irrigation system in the orchards, quality of irrigation water must be checked and it should be ensured that total soluble salts do not exceed 500 ppm and chloride content does not exceed 100-150 ppm.
Multiplication of Planting Material:
While planting orchards, it should be ensured that Nagpur mandarin is budded on Jambheri or Rangpur lime or Alemow and Kinnow on Jatti Khatti rootstock. Bud wood used must be free of virus and virus like diseases using in vitro shoot tip grafting and indexing techniques.
3. Methods of Irrigation for Mandarins Cultivation:
In north-east India or Coorg mandarin area, mandarins are cultivated as rainfed. But Nagpur and Kinnow mandarins are grown in irrigated area. There are several methods of irrigation like flood irrigation, furrow irrigation, basin irrigation and drip irrigation. Flood irrigation was common in Punjab, but it has increased Phytophthora foot rot infestation.
Similarly furrow irrigation also carries Phytophthora infestation from one plant to another. Basin irrigation is better, especially by using double ring system where irrigation water does not touch tree trunk. However, recently drip irrigation is becoming very popular not only in Punjab and Maharashtra but also in other mandarin growing areas. In drip system, initially 1-2 drippers are installed/plant and as the plants become bigger in size, the number of drippers is increased to 3-4.
Drip system is highly water efficient as it supplies water directly to root zone. Farmers, in some areas, are facing some problems of clogging in drip system and are switching over to microjet sprinkler system. But microjet sprinkler system supplies much higher quantities of water per plant per hour. Thus water requirement in this system is more than drip system but certainly much less than other irrigation methods like furrow, basin or flood.
Scheduling of Irrigation Water:
It is a common practice to irrigate at 6-7 days interval in summer and 10-15 days in winter months. Recent studies have indicated that irrigation scheduling needs to be based on quantum of depletion of soil moisture. Considering yield and fruit quality of Nagpur mandarin, moisture regime of about 60% available soil moisture was found most appropriate.
The water requirement of Kinnow has also been worked out month wise, the details of which are given in the Table below:
4. Training Pruning and Canopy Management of Mandarins Plants:
Height of plants in the beginning should be restricted to 0.7 to 1.0 m and thereafter side shoots should be encouraged. In initial years, 4-6 branches should be allowed to grow having wide angle with main trunk. Main objective at this stage should be to build strong framework.
Pruning of bearing trees is usually done only after harvest when diseased, dried, criss-cross, water sprouts and parallel branches are eliminated. Maximum success under organic management system can be achieved by using tree size controlling practices like thinning of branches, topping and hedging with the main objective of opening of tree canopy for facilitating better aeration and light penetration. After pruning, pasting of cut branches with Bordeaux paste and spraying with copper oxychloride (0.3%) or Bordeaux mixture (1%) must be done.
5. Nutrient Management of Mandarins:
For calculating organic nutrient requirements of mandarins, apart from considering recycling of biomass in the form of fallen leaves, prunings, fallen fruits etc. fertilizer doses applied under conventional system should be taken into consideration. Normally under conventional management, fertilizer doses of 600 gm of nitrogen, 200-300 gm of phosphorus as P2O5 and 150-600 gm of potash as K2O are added for Nagpur and Khasi mandarins per fully grown tree.
However, for Kinnow mandarin 880 gm of nitrogen and 440 gm of P2O5 is added besides 100 kg of FYM per tree. Entire quantity of FYM along with full quantity of phosphorus and potash and 50% dose of nitrogen is added before flowering during January-February after termination of stress period or in June as per the location and crop chosen in Nagpur mandarin. Remaining 50% of the nitrogen is applied in split doses after fruit set.
6. Selection of Crop and Induction of Mandarins Flowering:
In case of Khasi or Coorg or Kinnow mandarins flowering takes place only in March-April and fruiting in December to February months. However, in case of Nagpur mandarin as there is no distinct winter and for induction of flowering stress i.e. withholding of water to plants is done.
Thus in Nagpur mandarin Ambia fruiting can be taken in months of November-December by inducing flowering in February by giving stress to plants in December-January. Mrig Bahar fruiting can be taken in February-March, by inducing flowering in June – July months by giving water stress to plants in months of April – May.
Stress period is usually of 5-6 weeks duration, however, if soils are very deep then stress period can be extended to 7th or 8th week also.
7. Decline in Mandarins:
Decline in mandarins is quite common due to various factors. It usually happens when plants are infested with diseases like Phytophthora foot rot or virus diseases at the beginning itself and proper selection of plant material i.e. its freedom from diseases, has not been done.
Other reason is over cropping at young stage, which is common in Kinnow mandarin. Also in many cases, decline starts because of intercropping of mandarin orchards at young stage, which draws heavy amounts of nutrients from the soil. In addition to this, frequent irrigation of intercrops increases the infestation and spread of Phytophthora foot rot. Intercropping predisposes the mandarin plants for attack of insect pests and diseases.
Generally there is not a single cause but is the effect of many causes, which may vary from field to field or area to area. Some of the factors are beyond the control of the orchardist like, soil characters, drainage, salt concentrations, water logging, frost injuries, etc.
8. Yield and Harvesting Time of Mandarins:
Harvesting time for Khasi and Kinnow mandarin is from December-February depending upon location. In case of Nagpur mandarin Ambia crop matures in November-December months whereas Mrig crop matures in February-March months.
Yield in Khasi mandarin ranges 7-8 tons per hectare and in Nagpur mandarin it is 10-12 tons per hectare. In Kinnow it varies from 15-20 tons per hectare.
Pre-Harvest Fruit Drop:
Out of all the types of drops in citrus fruits, pre-harvest fruit drop causes very heavy losses to farmers, as fruits at this stage are of big size. There are many factors responsible for this drop. Infestation of fungi like Colletotrichum gloeosporioides and Botryodiplodia theobromae cause stylar end rot and as a result of this, heavy drop takes place.
This is particularly significant where fruit development phase passes through heavy rainfall as in Mrig crop in Nagpur mandarin and also in Khasi mandarin. In high rainfall areas infestation of Phytophthora also enhances pre-harvest fruit drop. Organic mulching, maintenance of moisture in rhizosphere, spraying of 0.3% copper oxychloride and Vermiwash (5%) at given intervals can reduce the fruit drop.
9. Varieties of Mandarins:
Mostly varieties like Nagpur mandarin, Kinnow, Khasi, Darjeeling or Sikkim are cultivated. Recently Central Citrus Research Institute, Nagpur has selected a clone N-4 having less seeds.