Xi called on countries to maintain the overall balance of the Earth's ecosystem so that the future generations will not only have material wealth, but also enjoy a good ecology.

"We must protect this planet like our own eyes, and cherish nature the way we cherish life," Xi said.

Vicente Gonzalez Loscertales, secretary-general of Bureau International des Expositions, said at the opening ceremony that the exhibition has attracted more than 110 countries and international organizations as well as over 120 nonofficial exhibitors.

The 162-day exhibition is poised to impress an expected 16 million visitors from home and abroad with a huge collection of plants, flowers and pavilions, as well as many ideas for green development.