The effect of integrated rice-frog ecosystem on rice morphological traits and methane emission from paddy fields

Integrated Rice-frog Ecosystem (IRFE) has the potential to reduce methane (CH₄) emission and maintain yields from paddy fields. However, the quantitative relationship between rice morphological traits and CH₄ emission remains to be explored. In this study, a 2-year field experiment was conducted to evaluate the effect of IRFE on rice morphological traits and CH₄ emission from paddy fields and the ecological mechanisms. This study was conducted to analyze twelve aboveground and eight underground rice morphological traits, rice yields, and CH₄ flux and emission from the paddy fields with six frog densities (0, 3750, 7500, 15,000, 30,000, and 60,000 frogs ha^-1). The results showed that IRFE reduced CH₄ emission by 24.70%-41.75% and 21.68%-51.21% in the 2018 and 2019 rice growth seasons, respectively. Moreover, CH₄ emission decreased with the increase of frogs. Frogs also increased the diameter, biomass, and volume of rice roots, thus promoting rice growth. Root biomass, thousand-grain weight, and harvest index were also closely related to the yield. Root porosity and oxygen secretion capacity were negatively correlated with CH₄ flux. Frogs increased root porosity and oxygen secretion, thereby reducing CH₄ emission. The present study demonstrated that reducing CH₄ emission and improving rice yields could be simultaneously achieved by altering rice morphological traits in IRFE.