WASHINGTON — The signature that President Barack Obama put on bill late Thursday evening signaled a victory for Maine potato growers and others in the industry after a hard-fought battle to keep potatoes on breakfast and lunch trays in schools across the nation.

On Thursday evening, the Senate approved a 2012 Agriculture funding bill that included a bipartisan amendment, authored by Sen. Susan Collins, R-Maine, that will protect the flexibility of schools to serve vegetables in the national school lunch and breakfast programs. It was then sent to Obama for his signature.

Earlier this year, the U.S. Department of Agriculture proposed new nutrition guidelines for the National School Lunch Program promoting more fruits, vegetables and whole grains while banning foods with trans fats and limiting starchy vegetables such as potatoes, green peas, lima beans and corn to a total of one cup per week. The proposed changes also sought to ban the starchy vegetables from the School Breakfast Program altogether.

Collins, U.S. Sen. Olympia Snowe, R-Maine, and Democratic 2nd District U.S. Rep. Mike Michaud immediately jumped into action. They maintained that while the potatoes are healthful, the way that some people prepare them is not. The trio noted that many schools are serving fried potatoes or mashed potatoes heaped in butter or covered in gravy instead of baking them or boiling them. All three also wrote letters to Agriculture Secretary Tom Vilsak decrying proposed rules that they felt are unfairly targeting the potato.

One medium-size baked potato has just 110 calories and provides 620 milligrams of potassium if eaten with the skin, according to figures from the Presque Isle-based Maine Potato Board. It also contains more vitamin C than one medium tomato and has 15 percent of the daily recommended intake of dietary fiber.

Collins co-authored an amendment with Sen. Mark Udall, D-Colo., passed unanimously in the Senate in mid-October. The wording of the amendment blocked the USDA from limiting potatoes and gave the USDA flexibility to regulate the preparation of potatoes when it issues the final version of its new school nutrition guidelines.

Collins said in a written statement Friday that the approval of the funding bill means the USDA “cannot proceed with a rule that would impose unnecessary and expensive new requirements affecting the servings of healthy vegetables, such as white potatoes, green peas, corn, and lima beans.”

When she addressed the Senate last month, Collins pointed out that the USDA had released guidelines last year calling for Americans to eat more vegetables. Officials from the USDA noted at the time that dietary intake of nutrients such as potassium, dietary fiber, calcium and vitamin D were “low enough to be of public health concern for both adults and children.”

Citing the new guidelines, Collins said that she was perplexed as to why the department would support a rule limiting vegetables such as potatoes, peas and corn that are good sources of such nutrients.

Collins said Friday that she recognizes the need to improve the nutritional standards in the school meals programs, and she supports USDA’s goal to increase the availability of all fruits, vegetables and whole grains in these programs and to ensure the foods served in schools are delivered in a fashion that meets the nutritional needs of children. Her provision allows schools the flexibility to make reasonable and suitable substitutions among affordable fresh and nutritious food options.

“The USDA estimates that this rule could have cost as much as $6.8 billion over five years,” said the senator. “The lion’s share of these costs would be incurred by the state and local agencies. The proposed rule would have also limited the flexibility that schools need to serve nutritious, affordable meals to their students.”

Melissa Hunter of Houlton has a stepdaughter attending school in SAD 29. She eats school lunch two or three days a week, and Hunter said that she always looks at the menu before the start of the school day.

“I think that schools now are doing much better in terms of helping our kids eat more healthy,” said the 43-year-old. “When I went to school, there was no such thing as a baked potato bar or fresh, local produce that the schools are serving today. We pretty much had hamburgers that were cooked and served in bags and salad with limp lettuce covered in oily dressing. I do think some changes need to be made in terms of what they offer.”

Hunter noted that the elementary schools in SAD 29 offer peanut butter and jelly sandwiches and assorted fresh fruit along with the planned meal on the menu.

“I don’t like that as much, because my daughter sometimes eats a peanut butter sandwich three days a week,” she said. “It is hard to control that. Other than that, I think the school lunches have really improved.”

Mary Burton, another Houlton resident with two children in SAD 29, agreed.

“My kids love the veggie sticks and dip that the district serves, and they have tried more foods over the years because of the school lunch,” she said. “My kids now love clementines that they were introduced to at school a few years ago, and they enjoy the baked potato bars when they are offered.”

At SAD 29, the only potato products on the menu this week were hash browns served one day and potatoes used to make shepherd’s pie. In SAD 1, potatoes were not included in the high school menu this week, while students at Presque Isle Middle School were served potato puffs twice and mashed potatoes once. Pine Street Elementary School served potato puffs one day and potato chips another.

Collins had support from a number of state and national organizations in her effort to preserve the potato, including from the National School Boards Association, the National Organization of Elementary School Principals, the National Potato Council, Maine Potato Board and the American Farm Bureau. Collins will be attending a luncheon hosted by the Maine Potato Board Monday to thank her for her work. Officials from the Maine Potato Board and the National Potato also will be present.