SAO PAULO, April 6 (Reuters) - Brazilian farmers are set to nearly double the area planted with transgenic sugarcane in the season starting this month, the world's main supplier of the genetically modified (GMO) crop, Centro de Tecnologia Canavieira (CTC), told Reuters.

CTC estimates that new cane varieties resistant to stem-boring insects will cover 70,000 hectares in the 2022/23 crop cycle, up from 37,000 hectares last year in Brazil, one of the biggest sugar producers in the world.

Brazil's GMO cane fields are still just a fraction of the planted area in the country, which totaled 8.2 million hectares (20.2 million acres) in the last harvest, but the planting estimates, which CTC rarely shares, underscore dramatic growth.

Five years after CTC received the world's first approval to sell transgenic cane, Luiz Paes, the company's commercial director, said in an interview this week that he sees growth in the segment continuing to accelerate.

"Farmers want to see it to believe it, and they need to have seedlings available to be able to grow. Now, having seedlings and results, both things let them expand," Paes said.

The company has developed four commercial varieties of transgenic cane so far, with new options allowing for planting in poorer soil, which would open up far more of the market.

Borers cause some 5 billion reais ($1.07 billion) of losses annually to Brazilian cane growers, CTC estimates, through lost productivity, lower sugar quality and insecticide costs.

Paes said the technology has been adopted by some 170 clients, which together account for a majority of Brazil's annual cane crush. No other companies have been commercially selling GMO sugarcane, according to CTC.

Some of the world's biggest sugar producers are shareholders in CTC, including Brazilian cooperative Copersucar, Sao Martinho and Raizen, a sugar and ethanol joint venture between Cosan and Shell.

With global sugar prices high and demand for sugar cane ethanol being boosted in Brazil by rising gasoline prices, CTC is also preparing to launch new, more productive varieties of conventional cane.

For the 2023/24 harvest, the "10,000 series" product may be commercially available, promising to raise yields by as much as 30% to 14-16 tonnes of sugar per hectare, Paes said.

The average yield in south central Brazil was below 10 tonnes per hectare in the last harvest, partly due to drought-related losses.

CTC has made research and development investments of around 1 billion reais ($213 million) in the last decade, Paes said.

The company is also trying to develop an herbicide-resistant transgenic sugarcane, which may be ready for launch in a couple of years. Paes highlighted that its commercial use would hinge on regulatory approvals.

($1 = 4.6892 reais) (Reporting by Roberto Samora Writing by Carolina Pulice Editing by Brad Haynes and Paul Simao)