To let her zucchini soak in the sun, Yu Xiuli, 50, rolls up the grass mat that was used to preserve heat inside her greenhouse at Sujiamiao village in Linzi district of Zibo, Shandong province, on Dec 21. [Photo/China Daily]

Beijing resident Cao Xia takes his lunch, stir-fried egg with zucchini, at his home in Honglian Beili community on Dec 23. [Photo/China Daily]

Yu Xiuli was not deterred by the chill on Dec 21, this year's winter solstice, when most parts of China saw the lowest temperatures of the year.

The 50-year-old farmer from Sujiamiao village in Shandong province got up early as she always has to tend to her vegetables.

Standing on the roof of her greenhouse, Yu rolled up a grass mat used to preserve heat for the zucchini planted inside. It was the last day the zucchini would stay in the greenhouse because the next day they were harvested and brought to a vegetable company in the city.

After bargaining, Chang Hai, a vegetable dealer, purchased Yu's zucchini for 4.4 yuan ($0.69) a kg.

Yu has been planting vegetables for more than a decade, and during that time, her average annual income has grown to about 40,000 yuan.

Late in the night, Chang dispatched a driver to transport the 15,000 kg of zucchini, which Chang purchased from different vegetable growers during the day, to Beijing's Xinfadi Wholesale Market, the main trading hub for vegetables in the city.

The truck loaded with vegetables arrived at Xinfadi in the early morning of Dec 23. Soon, they were sold wholesale to small dealers at a price of 5 yuan per kg. Chang said the gross income for a truckload of zucchini was 9,000 yuan this time. After deducting 2,000 yuan for the driver and other labor costs, Chang made little profit on the transaction.

Cao Xia, a resident in Beijing's Honglian Beili community, bought several zucchini at a community market for 8 yuan per kg, which he considered a high price. Cao cooked himself a lunch of stir-fried egg with zucchini.

In recent years, Zibo's Linzi district has set up a vegetable production base. The total planting area of zucchini and tomato is about 10,000 hectares, and growing these two vegetables generates an income of 1.57 billion yuan annually for local farmers.