Xi expressed hope that hybrid rice will one day be grown throughout the world.
Yuan was recently in news for questioning an Indian farmer from Bihar for beating his world record by harvesting 22.4 tonnes per hector.
It is "120 per cent fake", said Yuan, who is known to be the "father of hybrid rice" after his 19.4 tonnes record in 2011.
"I introduced the intensification method to China myself. It could increase yields by 10 to 15 per cent in low-yield fields, but it's not possible for fields that are already producing relatively high yields," Yuan was quoted as saying by Xinhua news agency.
Xi also chatted with other model workers, including an aerospace scientist, a village chief, a steel company employee and the country's first female tractor driver.
Three-day official holidays for the May Day starts today in China.