Workers driving forklifts shuttling between the storage warehouse and processing workshop poured baskets of fresh apples onto the automated sorting line at Jingning County Redleofu Fruit Industry in Pingliang, Gansu province.

After cleaning, spraying, drying, grading and boxing, 22 metric tons of apples were ready to be exported to Vietnam.

Gansu exported fresh apples valued at 190 million yuan ($26.2 million) from January to March, with 37 percent going to Vietnam, making it the biggest overseas market, data from Lanzhou customs showed.

Trade between China and Vietnam has benefited from policies including the China-ASEAN Free Trade Agreement and the Regional Comprehensive Economic Partnership, said Huang Zhiheng, an official from Lanzhou customs, adding that many goods enjoy tariff exemptions.

For example, companies can enjoy zero tariffs for exporting fresh apples to Vietnam by applying for RCEP certificates of origin.

Gansu, with its abundant sunshine and big temperature difference between day and night, is a major apple producer. Its fresh apples are exported to more than 20 countries and regions in Southeast Asia, Central Asia, North America and Europe.

Some of the apples exported to Vietnam are sold in that country, with others shipped on to other Southeast Asian markets.

Jiang Yubao, head of Pingliang customs, said many fruit companies have been exploring new markets in recent years as major foreign markets are saturated and the competition among similar producers is fierce.

He added that customs is helping companies make good use of preferential policies under free trade agreements, deal with foreign technical trade measures, and strengthen customs protection of intellectual property rights, to boost foreign trade and the high-quality development of local specialties.

Wang Zhiwei, general manager of Jingning County Redleofu Fruit Industry, said customs personnel have visited the company multiple times to provide guidance and help it apply for the most suitable certificates of origin.

"This has significantly reduced our customs clearance costs," he said. "As a result, we now have more bargaining power in foreign trade and have more advantages to expand our market."

Jingning apple, a national geographical indication product in China, is brightly colored, large and well-shaped, with abundant juice, moderate sweetness and sourness, long shelf life and high tolerance for storage and long-distance transportation. According to the China Council for Brand Development, its brand value reached 16.1 billion yuan, said He Pengfeng, Party secretary of Jingning county.

The area of apple orchards in the county exceeded 45,000 hectares last year, with a yield surpassing 1 million tons and a total output value of more than 7 billion yuan. The per capita net income of farmers from apples reached 8,000 yuan last year, 75 percent of their total income.