FOLIAR ENTRY AND INCORPORATION OF ATMOSPHERIC NITROGEN DIOXIDE INTO BARLEY PLANTS OF DIFFERENT NITROGEN STATUS

Area of Science:

• Plant Physiology
• Environmental Science
• Biochemistry

Background:

• Atmospheric nitrogen dioxide (NO2) is a common air pollutant.
• Plant nitrogen uptake is crucial for growth and influenced by environmental factors.

Purpose of the Study:

• To investigate the uptake of atmospheric NO2 by barley leaves.
• To determine how root nitrogen supply affects NO2 uptake and plant nitrogen content.
• To elucidate the impact of NO2 exposure on nitrogen metabolism and cycling in barley.

Main Methods:

• Hydroponically grown barley plants were exposed to controlled levels of NO2.
• Nitrogen content, nitrate, and reduced nitrogen forms were analyzed.
• 18N-labeled NO2 and nitrate were used to trace nitrogen assimilation and cycling.

Main Results:

• Leaf uptake of atmospheric NO2 significantly increased plant nitrogen content, particularly under low nitrate conditions.
• NO2 exposure led to increased levels of both nitrate and reduced nitrogen forms within the plant.
• Nitrate and nitrite reductase activities were affected by NO2 exposure, but NO2 uptake did not stimulate root nitrate absorption.

Conclusions:

• Barley plants can absorb atmospheric NO2 through their leaves, directly contributing to their nitrogen content.
• The plant's nitrogen status influences its response to NO2 exposure.
• Atmospheric NO2 affects internal nitrogen cycling and the plant's ability to regulate nitrogen uptake in response to root supply.