Nitrous Oxide (N2O) Estimation from Tropical Rice Paddy Under the Influence of Growth-Regulating Compounds

Nitrous oxide (N2O) is an important long-lived greenhouse gas and is a dominant contributor to stratospheric ozone depletion. Mitigating N2O emission from the rice paddies is one of the important challenges to global food security and climate change research while sustaining optimum productivity. We conducted a 2-year experiment to investigate the effect of different plant growth regulators (PGRs) on N2O emission to the atmosphere. The PGRs namely abscisic acid and cytozyme (20 mg L-1), kinetin (10 and 20 mg L-1) and tea extract (1:20 w/w) along with distilled water as control were sprayed at the tillering and panicle initiation stages of rice crop. Abscisic acid and kinetin (10 and 20 mg L-1) were found to bring about a significant (p < 0.01) reduction in N2O emission over control plants primarily through regulation of leaf growth, plant biomass, stomatal frequency, and xylem vessel size of rice plants. Cytozyme and kinetin application enhanced the flag leaf photosynthetic rate and grain yield through maximum partitioning of photosynthates to the developing grains. The PGRs were found to regulate the transport process of N2O, through manipulation of physiological and anatomical processes of rice plants. The present study indicates that kinetin (10 mg L-1) may be a sustainable mitigation measure for N2O emission reduction with efficient grain productivity and highest net revenue.