Friday, June 5, 2009
Turmeric (Curcuma longa) (Family: Zingiberaceae) is used as condiment, dye, drug and cosmetic in addition to its use in religious ceremonies. India is a leading producer and exporter of turmeric in the world. Andhra Pradesh, Tamil Nadu, Orissa,Karnataka, West Bengal, Gujarat, Meghalaya, Maharashtra, Assam are some of the important states cultivates turmeric, of which, Andhra Pradesh alone occupies 35.0% of area and 47.0% of production.
Turmeric can be grown in diverse tropical conditions from sea level to 1500 m above sea level, at a temperature range of 20-35oC with an annual rainfall of 1500 mm or more, under rain fed or
irrigated conditions. Though it can be grown on different types of soils, it thrives best in well-drained sandy or clay loam soils with a pH range of 4.5-7.5 with good organic status.
A number of cultivars are available in the country and are known mostly by the name of locality where they are cultivated. Some of the popular cultivars are Duggirala, Tekurpeta,Sugandham, Amalapuram, Erode local, Alleppey, Moovattupuzha, and Lakadong. The improved varieties of turmeric are- Suvarna,Suguna,Sudarsana,Prabha,Prathibha,Krishna,Sugandham,Roma,Suroma,Ranga,
Preparation of land
The land is prepared with the receipt of early monsoon showers.The soil is brought to a fine tilth by giving about four deep ploughing. Hydrated lime @ 500 kg/ha has to be applied for laterite soils and thoroughly ploughed. Immediately with the receipt of pre-monsoon showers, beds of 1.0 m width, 15 cm height and of convenient length are prepared with spacing of 50 cm between beds. Planting is also done by forming ridges and furrows.
Whole or split mother and finger rhizomes are used for planting and well developed healthy and disease free rhizomes are to be selected. Small pits are made with a hand hoe on the beds with a
spacing of 25 cm x 30 cm. Pits are filled with well decomposed cattle manure or compost, seed rhizomes are placed over it then covered with soil. The optimum spacing in furrows and ridges is
45-60 cm between the rows and 25 cm between the plants. A seed rate of 2,500 kg of rhizomes is required for planting one hectare of turmeric.
Farmyard manure (FYM) or compost @ 30-40 t/ha is applied by broadcasting and ploughed at the time of preparation of land or as basal dressing by spreading over the beds or in to the pits at
the time of planting. Zinc @ 5 kg/ha may also be applied at the time of planting and organic manures like oil cakes can also be applied @ 2 t/ha. In such case, the dosage of FYM can be reduced. Integrated application of compost (@ 2.5 t/ha) combined with FYM, biofertilizer (Azospirillum) and half recommended dose of NPK is also recommended.Fertilizers @ 60 kg N, 50 kg P2O5 and 120 kg K2O per hectare are to be applied in split doses as given below.
Table 2. Fertilizer schedule for turmeric (per ha)
Schedule N P2O5 K2O Compost/cow dung
Basal application - 50 kg - 30-40 tonnes
After 45 days 30 kg - 60 kg -
After 90 days 30 kg - 60 kg -
The crop is to be mulched immediately after planting with green leaves @ 12-15 t/ha. Mulching may be repeated @ 7.5 t/ha at 45 and 90 days after planting after weeding, application of
fertilizers and earthing up.
Weeding has to be done thrice at 60, 90 and 120 days after planting depending upon weed intensity. In the case of irrigated crop, depending upon the weather and soil conditions, about 15
to 23 irrigation's are to be given in clayey soils and 40 irrigation's in sandy loams.
Turmeric can be grown as an inter crop with with chillies, colocasia, onion, brinjal and cereals like maize, ragi, etc.
Leaf blotch- Leaf blotch is caused by Taphrina maculans and appears as small,oval, rectangular or irregular brown spots on either side of the leaves which soon become dirty yellow or dark brown. The leaves also turn yellow. In severe cases the plants present a scorched appearance and the rhizome yield is reduced. The disease can be controlled by spraying mancozeb in the pr0portion of 3gm per litre of water or combination of Carbendazim and Mancozeb in the ratio of 3gm in 1 litre of water .
Leaf spot- Leaf spot is caused by Colletotrichum capsici and appears as brown spots of various sizes on the upper surface of the young leaves. The spots are irregular in shape and white or grey in the centre. Later, two or more spots may coalesce and form an irregular patch covering almost the whole leaf. The affected leaves eventually dry up. The rhizomes do not develop well. The disease can be controlled by spraying zineb at the rate of 3gm per litre of water or Copper Oxy Chloride in the ratio of 3.5gm per litre of water.
Rhizome rot-The disease is caused by Pythium graminicolum or P.aphanidermatum. The collar region of the pseudostem becomes soft and water soaked, resulting in collapse of the plant and decay of rhizomes. Treating the seed rhizomes with mancozeb 50gms in 15 litres of water for 30
minutes prior to storage and at the time of sowing prevents the disease. When the disease is noticed in the field, the beds should be drenched with combination of carbendazim and mancozeb in the proportion of 3 gm per litre of water.
Nematode pests- Root knot nematodes (Meloidogyne spp.) and burrowing nematode (Radopholus similis) are the two important nematodes causing damage to turmeric. Wherever
nematode problems are common, use only healthy, nematode free planting material. Increasing the organic content of the soil also checks the multiplication of nematodes. Pochonia
chlamydosporia can be applied to the beds at the time of sowing @20 g/bed (at 106 Cu/g) for management of nematode problems.
Shoot borer-The shoot borer is the most serious pest of turmeric. The larvae bore into pseudo stems and feed on internal tissues. The presence of a bore-hole on the pseudo stem through which frass is extruded and the withered central shoot is a characteristic symptom of pest infestation. The adult is a medium sized moth with a wingspan of about 20 mm; the wings are orange yellow with minute black spots. Fully-grown larvae are light brown with sparse hairs. Spraying malathion at the rate of 2.5ml per litre of water or Dichlorovos at the rate of 2 ml per litre of water at 21 day intervals during July to October is effective in controlling the pest
infestation. The spraying has to be initiated when the first symptom of pest attack is seen on the inner most leaf.
Rhizome scale-The rhizome scale infests rhizomes in the field(at later stages of the crop) and in storage. Adult (female) scales are circular (about 1mm diameter) and light brown to grey and
appear as encrustations on the rhizomes. They feed on sap and when the rhizomes are severely infested, they become shrivelled and desiccated affecting its germination. Treat seed material with quinalphos by dissolving 7.5ml in 10 litres of water (for 20-30 minutes) before storage and also before sowing in case the infestation persists. Discard and do not store severely infested rhizomes.
For certified organic production, at least 18 months the crop should be under organic management i e only the second crop of turmeric can be sold as organic. The conversion period may be relaxed if the organic farm is being established on a land where chemicals were not previously used, provided sufficient proof of history of the area is available. It is desirable that organic method of production is followed in the entire farm; but in the case of large extent of area, the transition can be done in a phased manner for which a conversion plan has to be prepared.As a mixed crop it can also be grown or rotated with green manure/legumes crops or trap crops enabling effective nutrient built up and pest or disease control. When grown in a mixed cultivation system, it is essential that all the crops in the field are also subjected
to organic methods of production.
In order to avoid contamination of organically cultivated plots from neighboring non-organic farms, a suitable buffer zone with definite border is to be maintained. Crop grown on this isolation belt cannot be treated as organic. In sloppy lands adequate precaution should be taken to avoid the entry of run off water and chemical drift from the neighboring farms. Proper soil and
water conservation measures by making conservation pits in the inter spaces of beds across the slope have to be followed to minimize the erosion and runoff. Water stagnation has to be
avoided in the low lying fields by taking deep trenches for drainage.
For organic production, traditional varieties adapted to the local soil and climatic conditions that are resistant or tolerant to diseases, pests and nematode infection should be used. All crop residues and farm wastes like green lop pings, crop residues, grasses, cow dung slurry, poultry droppings etc. available on the farm can be recycled through composting, including vermicomposting so that soil fertility is maintained at high level. No synthetic chemical
fertilizers, pesticides or fungicides are allowed under organic system. Farmyard manure may be applied @ 40 t/ha along with vermi compost @ 5-10 t/ha and mulching with green leaves @ 12-
15 t ha-1 at 45 days intervals. Based on soil test, application of lime/dolomite, rock phosphate and wood ash has to be done to get required quantity of phosphorus and potassium
supplementation. When the deficient conditions of trace elements become yield limiting, restricted use of mineral/chemical sources of micro nutrients by soil application or foliar spray are allowed as per the limits of standard setting or certifying organizations.Further, supplementation of oil cakes like neem cake (2 t/ha), compost(5 t/ha) and suitable microbial cultures of Azospirillum and phosphate solubilizing bacteria will improve the fertility and yield.
Use of biopesticides, biocontrol agents, cultural and phytosanitary measures for the management of insect pests and diseases forms the main strategy under organic system. Spraying
Neemgold in the ratio of 50 ml in 15 litres of water or neem oil 50ml in15 litres during July-October (at 21 day intervals) is effective against the shoot borer.
Selection of healthy rhizomes, soil solarization and incorporation of Trichoderma, seed treatment and soil application of biocontrol agents like Trichoderma or Pseudomonas multiplied in suitable carrier media such as coir pith compost, well rotten cow dung or quality neem cake may be done at the time of sowing and at regular intervals to keep the rhizome rot disease in check.To control other foliar diseases spraying of copper oxy chloride 3 gm in 1 litre of water. Application of quality neem cake mentioned earlier along with the bioagents Pochonia chlamydosporia will be useful to check the nematode population.
Depending upon the variety, the crop becomes ready for harvest in 7-9 months after planting during January-March. Early varieties mature in 7-8 months, medium varieties in 8-9 months and late varieties after 9 months. The land is ploughed and the rhizomes are gathered by hand
picking or the clumps are carefully lifted with a spade. The harvested rhizomes are cleared of mud and other extraneous matter adhering to them.
Fresh turmeric is cured for obtaining dry turmeric. The fingers are separated from mother rhizomes. Mother rhizomes are usually kept as seed material. Curing involves boiling of fresh rhizomesin water and drying in the sun.In the traditional method of curing, the cleaned rhizomes are boiled in water just enough to immerse them. Boiling is stopped when froth comes out and white fumes appear giving out a typical odour. The boiling should last for 45-60 minutes when the rhizomes turn soft. The stage at which boiling is stopped largely influences the colour and aroma of the final product. Over cooking spoils the colour of the final product while under-cooking renders the dried product brittle.
In the improved scientific method of curing, the cleaned fingers (approximately 50 kg) are taken in a perforated trough of 0.9 m x 0.5 m x 0.4 m size made of GI or MS sheet with extended parallel handle. The perforated trough containing the fingers is then immersed in a pan; 100 litres of water is poured into the trough so as to immerse the turmeric fingers. The whole mass is boiled till the fingers become soft. The cooked fingers are taken out of the pan by lif ting the trough and draining the water into the pan. The water used for boiling turmeric rhizomes can be used for curing fresh samples. The processing of turmeric is to be done 2 or 3days after harvesting. If there is delay in processing, the rhizomes should be stored under shade or covered with sawdust or coir dust.
The cooked fingers are dried in the sun by spreading them in5-7 cm thick layers on bamboo mats or drying floor. A thinner layer is not desirable, as the colour of the dried product may be adversely affected. During night time, the rhizomes should be heaped or covered with material which provides aeration. It may take 10-15 days for the rhizomes to become completely dry.
Artificial drying, using cross-flow hot air at a maximum temperature of 60 degree centigrade also gives a satisfactory product. In the case of sliced turmeric, artificial drying has clear advantages in giving a brighter coloured product than sun drying which tends to undergo surface bleaching. The yield of the dry product varies from 10-30% depending upon the variety and the location where the crop is grown.
Dried turmeric has a poor appearance and a rough dull outer surface with scales and root bits. The appearance is improved by smoothening and polishing the outer surface by manual or mechanical rubbing.Manual polishing consists of rubbing the dried turmeric fingers on a hard surface. The improved method is by using a hand operated barrel or drum mounted on a central axis, the sides of which are made of expanded metal mesh. When the drum filled with turmeric is rotated, polishing is effected by abrasion of the surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum. Turmeric is also polished in power operated drums. The yield of polished turmeric from the raw material varies from 15-25%.
The colour of the processed turmeric influences the price of the produce.For an attractive product, turmeric powder (mixed with little water) may be sprinkled during the last phase of polishing.
Preservation of seed rhizomes
Rhizomes for seed purpose are generally stored by heaping in well ventilated rooms and covered with turmeric leaves. The seed rhizomes can also be stored in pits with saw dust, sand along with leaves of Strychnos nuxvomica (kanjiram). The pits are to be covered with wooden planks with one or two openings for aeration. The rhizomes are to be dipped in quinalphos 7.5ml in 10 litres of water solution for 15 minutes if scale infestations are observed and in mancozeb 35gm in 10 litres of water to avoid storage losses due to fungi.