NANCHANG, March 19 (Xinhua) -- After four years of research, experts at Jiangxi Agricultural University have developed cole flowers in 17 colors, which could help boost tourism in east China's Jiangxi Province.

Now that spring is in the air, flower tours have attracted crowds of tourists to rural areas, especially Jiangxi, which is famous for its beautiful cole flowers.

"The sea of cole flowers is a signature tourism resource in Jiangxi, but the industry has been long restricted by the limited number of flower colors," said Fu Donghui, who is in charge of the research.

Fu started researching cole flowers in 2002. In the past four years, his team has used a variety of ways to create new flower seeds.

In 2017, Fu cultivated four new colors, including purple and crimson, based on 13 other colors. Nine of the 17 colors are already stable for large scale plantation, Fu said.

Fu also helped prolong the flowering phase of the flowers for 10 days.

"One day of prolonged flowering can help bring in an extra 10 million yuan (1.6 million U.S. dollars) of revenue for Wuyuan," Fu said, referring to one of the most famous counties for cole flowers.

Compared to regular cole flowers, the new types look better and contain more anthocyanin, a type of blue, violet, or red pigment, according to Fu.

But challenges also stand in the way. Fu said that cole flowers can only be grown once or twice a year, and it takes four to five years before a new color is ready for large-scale growth.

"Right now I am cultivating blue cole flowers," Fu said.

In several counties in Jiangxi, white cole flowers are already being planted in pilot projects.

"We hope to create more amazing colored cole flowers in the future," Fu said.