Some 4,000 farmers in south China's Shenzhen City have received "green certificates" after they were trained by the local government on vegetable, fruit and flower planting knowledge, according to Huang Mintong, deputy director of the local agricultural technology popularization center.

Another 400 are to be trained this year in the "green certificate" program, which was kicked off three years ago.

"Modern agriculture requires farmers to master advanced agricultural science and technology," Huang said.

With vegetable fields covering over 50,000 mu (about 3,333 hectares), orchards covering 180,000 mu (about 12,000 hectares) and flower fields more than 10,000 mu (about 667 hectares) in Shenzhen, the city not only offers products to local markets but also markets in Hong Kong and overseas, Huang said.

Farmers should have received a middle school education if they want to be allowed to join the training program. Trainees can get allowances and free reference materials during their study. Those with "green certificates" enjoy the priority right to rent vegetable, fruit and flower fields, according to Huang.