Aerial photo taken on May 22, 2018 shows a tractor weeding at a grape planting base in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region. (Xinhua/Wang Peng)

A tractor weeds at a grape planting base in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, May 22, 2018. (Xinhua/Wang Peng)

Aerial photo taken on May 22, 2018 shows a tractor weeding at a grape planting base in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region. (Xinhua/Wang Peng)

A worker transplants grapes at a grape planting base in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, May 22, 2018. (Xinhua/Wang Peng)