New Delhi, April 5: Armed with hand-held canisters of plant-friendly microbes, biochemist Bala Gopalan Unni is hoping to turn Assam’s celebrated muga silk stronger, softer, and more plentiful than it is today.

A cocktail of microbes called rhizobacteria that Unni has helped put together, improves the quality and quantity of silk when sprayed over plants that host silkworms that make muga, exclusive to the region.

Muga, which grows only in India’s northeastern states and comes with an indelible natural, shimmering golden colour, is one of India’s most expensive silks. It is used in traditional woven materials, fabrics and even umbrellas that absorb ultraviolet rays.

In an effort to find ways to boost the quality and production of muga silk, scientists at the North East Institute of Science and Technology (NEIST) in Jorhat turned their attention to a class of rhizobacteria that can promote growth.

“These microbes increase carbohydrates, essential fatty acids and proteins of the host plants,” Unni, a senior scientist at the biology division of NEIST said. “The silkworms get better nutrition and produce more silk of higher quality,” he said.

The quantity of silk produced from such well-fed silkworms can increase by 10 to 30 per cent, Unni said.

An increase in elasticity and longevity leads to production of stronger and softer variety of silk, he said.

Scientists estimate some 40,000 households along Assam’s stretches of the Brahmaputra are involved in harvesting muga silk. However, a decline in muga production in recent years is worrying farmers as well as scientists.

According to muga silk scientists, attacks by pests and parasites, non-availability of high-yielding seeds and lack of personnel to take up farming operations have contributed to this decline.

Last year, Unni and his colleagues at the NEIST came out with another silk-boosting technology for farmers that has its origin in fruit juices of a medicinal plant called Terminalia chebula.

“The fruit extract has the ability to kill a dreaded bacteria that infects the muga silkworm,” Unni said.

Spraying the fruit extract on host plants’ leaves protects silkworms from the bacteria, leading to a higher yield from each plant. The NEIST and the Central Muga Eri Research and Training Institute in Jorhat are now trying to persuade silk farmers across Assam adopt the technology.

According to researchers, field tests of spraying of rhizobacteria have so far yielded positive results and evoked good feedback from farmers.

Silk farmers and processors, however, appear unhappy with the tardy pace of application of the technology.

“Muga production witnessed a decline last year because of inclement weather and the technology isn’t moving fast enough,” said Dulal Chowdhury, a silk fabric processor with Muga Vastra Udyog who sells umbrellas made of muga silk.

Unni admits that the cost of rhizobacteria spray is yet to be worked out. The NEIST has been producing the spray to conduct experiments. It, however, hopes to transfer the technology to the industry.

The rhizobacteria release certain biochemicals that allow plants to draw nutrients from the soil which they are unable to do without the help of the bacteria.