Foliar N₂ O emissions constitute a significant source to atmosphere.

Area of Science:

• Environmental Science
• Biogeochemistry
• Plant Physiology

Background:

• Nitrous oxide (N₂ O) is a potent greenhouse gas and ozone-depleting substance.
• Soil emissions are well-known, but foliar N₂ O emissions from plants are less understood.
• Previous studies indicated potential foliar N₂ O emission under lab conditions, but in situ universality and significance were unclear.

Purpose of the Study:

• To investigate the in situ foliar N₂ O emission capacity across diverse plant taxa.
• To identify the source and mechanism of N₂ O production in plant foliage.
• To quantify the global significance of foliar N₂ O emissions.

Main Methods:

• Studied N₂ O emissions from 25 common plant taxa under in situ conditions.
• Utilized ¹⁵ N isotopic labeling to trace the origin of foliar N₂ O.
• Employed biocides and endophyte manipulation to determine the role of endophytic bacteria.

Main Results:

• Foliar N₂ O emissions were predominantly derived from nitrate reduction.
• Endophytic bacteria within foliage were identified as the primary drivers of N₂ O production.
• Estimated global foliar N₂ O emissions to be 1.21-1.01 Tg N₂ O-N year^-1, contributing 6-7% to the global total.

Conclusions:

• In situ foliar N₂ O emission is a universal process across terrestrial plants.
• Endophytic bacteria play a crucial role in plant-derived N₂ O emissions.
• Foliar N₂ O emissions represent a significant, underappreciated component of the global N₂ O budget, requiring consideration for mitigation strategies.