LAUSR

To investigate the effects of the spatial distribution of rice root systems on dissolved CH4 and CH4 emissions and the CH4 transport efficiency of aboveground plant parts in paddy fields. A two-year field and leaf cutting experiment was conducted on seven rice varieties, and we determined the dynamics of CH4 emissions, root system traits and dissolved CH4 concentrations in different soil layers, and the CH4 transport efficiencies of the leaf and stem sheath. CH4 emissions, the root distribution and the distribution of dissolved CH4 concentration showed large discrepancies among the different rice varieties. Correlation analysis and structural equation modeling (SEM) revealed that CH4 emissions had strong negative associations with root morphological traits (root dry weight, root area index and root volume density) and a clear positive correlation with dissolved CH4 concentrations in the 0–20 cm soil layer. In addition, the root system had an indirect negative correlation with CH4 emissions by influencing the dissolved CH4 concentrations. Furthermore, root traits had strongly positive correlations with grain yield. In the aboveground parts, the CH4 transport efficiencies of the leaf (20–70%) and stem sheath (30–80%) presented large differences among the different rice varieties, and CH4 emissions exhibited significant positive correlations with leaf CH4 transport efficiency and leaf dry weight. Our results suggest that varieties with larger and deeper root distributions and lower leaf dry weight can decrease CH4 emissions in paddy fields and maintain higher grain yield.