Hundreds of thousands of people in India's most populous state are attempting to plant 50 million trees over 24 hours in hopes of shattering the world record.
Officials in Uttar Pradesh distributed millions of saplings to be planted across the state to help India's efforts to increase its forest cover, and to get into Guinness World Records for the most trees planted in a day.
The current record is 847,275, set in Pakistan in 2013.
More than 800,000 people, including students, MPs, government officials, housewives and volunteers from nonprofit organisations, headed out on Monday to plant the saplings at designated spots along country roads and highways, rail tracks and forest lands.
Uttar Pradesh's top elected official, Chief Minister Akhilesh Yadav, said that planting 50 million trees would spread awareness and enthusiasm about afforestation and environmental conservation.
"The world has realised that serious efforts are needed to reduce carbon emissions to mitigate the effects of global climate change. Uttar Pradesh has made a beginning in this regard," Yadav told volunteers in the city of Kannauj, 250 kilometres southwest of the state capital, Lucknow.
India's government is encouraging all 29 states to start tree-planting drives to increase the country's forest cover as part of commitments made at last year's climate change summit in Paris.
The government has designated more than $US6.2 billion ($A8.19 billion) for tree-planting across the country, in keeping with its pledge to push India's forest cover to 95 million hectares by 2030.
Meanwhile, auditors from Guinness World Records were moving around in the state to check on the numbers.
Last year, Uttar Pradesh entered Guinness World Records for the largest distribution of saplings by donating more than one million trees that were planted at 10 locations in the state.
