Plant morphophysiological and anatomical factors associated with nitrous oxide flux from wheat (Triticum aestivum).

Experiments were conducted to study the dynamics of nitrous oxide (N2O) emission from wheat varieties viz., Sonalika, HUW 468, HUW 234 and DBW 14 grown in alluvial soils of North Bank Plain Agroclimatic Zone of Assam, India. Attempts were made to find out the relationship of N2O emission with plant morphophysiological, anatomical and soil properties. N2O fluxes from wheat varieties ranged from 40 µg N2O-N m⁻² h⁻¹ to 295 µg N2O-N m⁻² h⁻¹. Soil organic carbon and soil temperature have shown significant relationship with N2O flux. The rate of leaf transpiration recorded from the wheat varieties at different growth stages exhibited a positive correlation with N2O emission suggesting that movement of N2O along with the transpirational water flow may be an important mechanism of N2O transport and emission through wheat plants. Anatomical investigation by scanning electron microscope revealed that N2O emission has relationship with stomatal frequency of leaf and leaf sheaths. Variety HUW 234 with the highest stomatal frequency of leaf and leaf sheath also recorded higher seasonal N2O emission compared to other varieties. Seasonal N2O emission (E(sif)) of the varieties ranged from 3.25 to 3.81 kg N2O-N ha⁻¹. Significant variations in E(sif) values were recorded within the varieties.