मूगा रेशम के कीट के बारहमासी मेजबान वृक्ष, सोम (पर्सिया बॉम्ब्सीना) की खेती की तकनीक।

Muga silkworm Antheraea assamensis Helfer, is a sericigenous insect secreting a golden yellow coloured lustrous silk. This unusual colour and strong nature of the thread produced from the cocoon of this silkworm are the two important features for which this silkworm is termed unique.

Muga silkworm is multivoltine in nature, with six broods per year, including two crops each of pre-seed, seed and commercial. ‘Chotua’ (reared during March-April) and ‘Bhodia’ (reared during August-September) are seed crops, ‘Jethua’ (May-June) and ‘Kotia’ (October-November) are commercial crop while ‘Jarua’ (December-January) and ‘Aherua’ (June-July) are pre seed crops.

Jethua and Kotia are the only crops used for commercial production while the rest of the crops are meant only for obtaining seeds for supplying and continuing rearing in favorable seasons. Antherea assama is confined to only Brahmaputra Valley of India in the world.

The Primary Host plant of Muga silkworm is Som (Persea bombycina) and Soalu (Litsea polyantha). Accounting to the State Sericulture Department, the State has produced 114.56 MT Muga Raw Silk, during the year 2011-12 as against 113.28 MT Muga Raw Silk, produced in the State during the year 2010-11. (http://databank.nedfi.com/content/sericulture-assam)     

Som Cultivation

Propagation:-

Som (Persea bombycina) is commonly propagated from seeds. Systematic plantation of muga host plant is a primary need for enhancing production and productivity of muga raw silk. It is desirable to collect the seeds from the healthy plants for growing of seedlings. Som seeds are initially sown in nursery beds or in poly bags and transplanted later to the field for raising systematic plantation.

सोम वृक्ष                 Som Plantation

Nursery Techniques:-

• Select high and shady land free from water logging.
• Plough the land at least up to 30 cm depth and level properly.Make seed beds of 5m x 1m in size with 10-15 cm high.
• Maintain a gap of 30 cm between two seed beds for cultural operation as well as for drainage.
• Apply 50 kg compost and 200g. 10% BHC powder in each bed and mix with the soil properly.
• Collect mature and ripe seeds from the Som plants during the month of April-May.
• Wash the seeds thoroughly in running water to remove the pulp completely.
• Seeds that submerge and gather at the bottom of the container during washing should be    collected and allowed to dry in shady place.
• Generally, seeds with 3.0 g. in weight and 7.0 mm in diameter are to be selected for sowing
• Mix 2.0 g. ceresin powder with 1 kg. Seed to prevent fungal infestation.
• Sow the seeds in ready nursery beds within a week.
• Sow maximum 8000 seeds per bed at a depth of 1 cm and 15 cm apart between the two seeds for proper germination.
• After sowing, mulch the seed bed with a thin layer of thatch or dry hay.
• Seeds can also be sown directly at polythene tube  filled with a mixture of sand, soil and FYM (1:1:1)
• Water the seed beds at regular intervals for timely germination.
• Germination will take place within 40-60 days in Som seeds.
• Remove weeds from the nursery beds at regular intervals for healthy growth of seedlings.

Maintenance of  Som plant Nursery bed:-

• For proper and healthy growth, transplant 2-3 months old seedlings in to polythene bags of the size of 15-20 cm filled with sand, soil and FYM in 1:1:1 ratio.
• Keep the poly bags under shad after transplanting and water at regular intervals preferably in the morning or evening
• Remove the weeds time to time from the polythene bags for proper growth.

Generally, seedlings are attacked by aphids or some other insect pests. In such cases, 0.03% Dimecron may be sprayed at 15 days interval.

Plantation Techniques for Som :-

• Select high land free from water logging and plough the land properly.
• Prepare pits of 30x30x30 cm at 3m x 3m spacing in row to row.
• Add 5 kg compost/FYM  in each pit and mix with the soil properly.
• Transplant 6-8 months old seedlings in to the ready pits after removing the poly bag during rainy season (June to August).
• To prevent grazing animals, fencing around the seedlings or around the garden is necessary.
• Seasonal intercrops like zinger, turmeric, potato or tomato etc. may be grown at the  space between the rows of plants from the beginning of plantation onward which give an additional income from the land till gestation period of plants.

Maintenance of Som plantation:-

• Apply 5 Kg FYM and 40 g urea, 60 g SSP and 15 g.MOP to each plant by making circular ring around the plant from 2^nd  year onward up to 5^th years.
• After 5^th years, the quantity of FYM and NPK is doubled and applied in split doses during April and September.
• Once the seedlings attain a height of 3 ft., tip-plugging is need for more branching.
• After each rearing (from 3^rd years onward), light pruning is undertaken for getting  better quality and quantity foliage.
• Heavy pruning or pollarding of the main stem/trunk may be carried out at a height of 5 ft. after attaining the age of 6-7 years. Pollarding is generally done in the month of September-October.    

मूगा रेशम कीट          Muga Silkworm Feeding on Som plant

Disease and Pest Management in Som cultivation:-

Som plants are prone to various disease and pests that affect the quality and quantity of leaves and ultimately affect on cocoon production. The leaf yield loss due to disease and pest is estimated about 20-30 percent.

Authors:

P.K.Handique*, and R.Singh

Central Silk Board,

 Central Muga Eri Research and Training Institute, Lahdoigarh, Jorhat, Assam

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