Greenhouse Gas Emissions and Stem Aerenchyma Development of Rice Under Different Water and Nitrogen Regimes

Rice cultivation is an important source of GHG emissions, particularly CH₄ and N₂O, which are strongly influenced by water and N management. However, the relationship between GHG emissions and stem aerenchyma development among rice varieties remains poorly understood. This study evaluated CH₄ and N₂O emissions and stem aerenchyma development in two rice varieties, PTT1 and KDML105, cultivated under flooded and non-flooded conditions with two N regimes (0 and 120 kg ha^-1). GHG fluxes were measured at three growth stages: before maximum tillering, panicle initiation, and flowering, while stem aerenchyma was assessed at the early heading stage. The results showed that water conditions and N fertilizer significantly affected cumulative CH₄ emissions, whereas there was no significant effect of rice variety. Applying both water and N also increased GWP and GHGI in rice cultivation, with little difference between the rice varieties. Notably, stem aerenchyma development was not significantly associated with GHG transport under different conditions. These findings demonstrate that water and N management affected rice physiological responses, but stem aerenchyma development alone may not be associated with GHG transport under specific environmental conditions. These results provide valuable guidance for optimizing water and N management in rice production systems to maintain crop productivity while reducing environmental impacts.