Though India is the world’s leading consumer of silk, production of the lustrous and shiny fibre spun out of silkworms has consistently fallen short of the growing demand in the country.
But, statistics available from the Central Silk Board (CSB) show that raw silk production in India has recorded a significant increase during the last 10 years – up from 23,678 metric tonnes during 2012-13 to 36,582 metric tonnes during 2022-23.
Reasons for surge in production of silk
Scientists at Central Sericultural Research and Training Institute (CSRTI) in Mysuru, which is pioneering research in tropical sericulture, pointed out that India has managed to increase raw silk output by almost 13,000 metric tonnes during the last decade, bringing down its reliability on imports from China, on account of two main reasons – high yielding variety of mulberry plants and superior quality bivoltine cocoon breeds.
While the first reason was the adoption of high yielding variety of mulberry plants, whose leaves are the sole food for mulberry silkworms, the second reason is the substantial shift from rearing inferior quality multivoltine cocoons to the production of bivoltine cocoons, a hybrid variety that is high yielding and superior in quality.
CSRTI scientists, including its Director Dr. Gandhi Doss and Dr. M.K. Raghunath, recalled that local varieties of mulberry plants were yielding no more than 18 metric tonnes per hectare per year. After persistent research aimed at developing high-yielding mulberry varieties, a major breakthrough in leaf productivity and quality was achieved in 1997 when the institute came out with a new mulberry variety Victory -1 (VI). This variety has a yield potential of 60 metric tonnes per hectare per year. It has revolutionised silk productivity by covering up to 90% of mulberry gardens in southern Indian states over the last 25 years, the scientists pointed out.
Area under cultivation
The total area under mulberry plantations across India was 2.53 lakh hectares during 2022-23, up from 2.24 lakh hectares during 2017-18. Farmers have progressively uprooted the low-yielding mulberry variety and replaced them with the high-yielding variety VI.
The second major reason for the spike in raw silk production is the increase in the rearing of superior quality bivoltine cocoons suitable to India’s temperate climate.
Much of the raw silk produced in India comes from the yellowish-coloured multivoltine cocoons while the high-quality silk used to manufacture the sought-after Indian sarees was woven out of bivoltine silk imported from China.
India sought help from Japan
Government of India had requested the government of Japan to provide technical assistance for bivoltine silk production in the nineties, paving the way for start of a Japan International Co-operation Agency (JICA) project for promotion and popularizing of bivoltine technology in India.
Over the last two decades, personnel from the CSRTI along with officials from the Department of Sericulture have been engaged in disseminating the technologies developed in the laboratory, leading to increased production of bivoltine cocoons by the farmers.
Bivoltine silk production increased from 2,559 metric tonnes in 2012-13 to 5,874 metric tonnes in 2017-18 before recording 8,904 metric tonnes in 2022-23. Though multivoltine silk still accounted for 27,654 metric tonnes in 2022-23, the quantum increase in bivoltine silk production will not only help meet the country’s demand for superior quality silk required for manufacture of sarees and garments, it will also bring down India’s dependence on silk imported from China.
With bivoltine cocoons, a reeler needs only 6 kg of cocoons to produce one kg of raw silk against the 13 to 15 kg of cocoons that were required earlier.
“This is possible due to the improved silkworm breed, mulberry variety and rearing technologies,” said CSRTI scientist Dr. K. B. Chandrashekar. Also, the individual cocoon filament length has increased from 600-800 metres to 1,000 to 1,200 metres, thereby reducing the cost of production of silk fabric.
Apart from high-yielding variety of mulberry plant and production of superior quality bivoltine cocoons, the other interventions by CSRTI that helped boost raw silk production in India include the shift from leaf feeding to shoot feeding, besides pest control measures and use of disinfectants.
“Earlier, mulberry leaves were plucked and fed to the silkworms. Now, the entire shoot of mulberry is fed, thereby saving labour and time,” pointed out CSRTI scientist Dr. Bala Saraswathi S.
What is in pipeline
To further boost silk production, CSRTI is looking forward to release of disease-resistant and temperature tolerant breeds, which are still in the pipeline. The optimum temperature required in the rearing house for a silkworm to give its maximum output is anywhere between 24 to 26 degree centigrade.
“The new breeds will tolerate plus or minus two degrees, and offer better survival rate,” said Dr. Chandrashekar.
CSRTI-Mysuru has been pursuing research aimed at enhancing production and productivity of silk in Karnataka, Andhra Pradesh, Tamil Nadu, Telangana and Kerala, besides Madhya Pradesh and Maharashtra, through its extension network comprising Regional Sericulture Research Stations and Research Extension Centres. The institute has also imparted training to more than 53,000 persons, including farmers and 800 foreign nationals, in various aspects of sericulture technology, said Dr. Gandhi Doss.