An 86 percent stock jump in just one week? Ceres Inc. can thank the rain.

The Thousand Oaks company sells genetically modified seeds for biofuel crops. Its shares were hit hard last year when a drought in Brazil stunted growth of the crop, called sweet sorghum. But now an analyst is predicting that Ceres will soon announce strong yields from the recent harvesting season.

Ceres stock has soared on the news, closing up nearly 86 percent to $3.90 for the week ended June 12. It was the biggest gainer on the LABJ Stock Index. (See page 38.)

Pavel Molchanov, an analyst at Raymond James & Associates in St. Petersburg, Fla., wrote in an investor note last week that improved yields will help jump-start Ceres’ sales in Brazil.

“The better the yields, the more customers will line up at Ceres’ door to buy seeds,” he told the Business Journal. “The goal of Ceres is to accelerate the adoption curve for sweet sorghum by the Brazilian mills.”

Ceres develops seeds for sweet sorghum, a grass that has been historically used as a sugar substitute. The company sells the seeds to mills in Brazil that use them to grow off-season crops in rotation with sugar. Today, sweet sorghum is fermented into ethanol for the biofuels market.

Ceres went public in February last year. But its share price quickly soured on news that the drought depleted sweet sorghum harvests during the peak growing months of January through March.

But it looks like the weather has improved this year.

A Ceres spokesman declined to comment about the analyst report, but said the company announced during its last earnings call that “weather conditions were generally favorable during the current sweet sorghum growing season in Brazil and that the majority of plantings were progressing well.”

The company plans to report results of the harvest during its earnings call next month.

Ceres’ shares had languished this year, bottoming out at $1.96 in early June.

Molchanov said Ceres is still a young company that relies on news to keep investor interest high. He expects the company’s upcoming harvest announcement to further bolster its stock.

“This is a story stock,” he said. “It’s an early stage business and in the absence of news flow, it languished.”