Ceres, the Thousand Oaks-based energy crop firm, has delayed its initial public offering again.

It also said Friday that its existing investors might buy as many as a fifth of the shares slated to hit the market and that a drought in Brazil could hurt it sweet sorghum yields.

The pushed back its planned initial public offering on the Nasdaq for the second time this month. Ceres’ public disclosure that existing investors are willing to deepen their ties with the firm could be a sign that it is having trouble persuading outside investors to capitalize the next stage of the company’s growth.

In late January, Ceres declared its intention to hit the markets on Feb. 9 and raise as much as $132 million by selling shares at $21 to $23 a share. Shortly before shares were slated to begin selling, Ceres cut its expected pricing range to $16 to $17 and pushed the date back to Feb. 16.

While the company’s offering remains on the Nasdaq’s expected IPO calendar, no deal appears to have taken place yet. In a regulatory filing on Feb. 17, the company said that its existing investors had given non-binding signals of interest to buy as many as 1 million of 5 million shares being offered and that a “significant drought” in south-central Brazil could hurt the outlook for the firm’s crops.

“We are receiving reports that while some of the 2011/2012 sweet sorghum crops being produced from our seeds are growing quite well, others are suffering from the adverse weather conditions,” Ceres said in a statement. “As a result, we expect that this drought will likely lead to overall reduced yields for the 2011/2012 sweet sorghum crops and may adversely affect the demand for our seeds for the 2012/13 growing season.”