Effects of integrated rice-frog farming on soil bacterial community composition

Rice-fish integrated farming model has become one of the main directions for sustainable agricultural development due to its good ecological and environmental effects and ability to produce green rice (Oryza sativa L.) that meets the market's food safety needs. Its study characterizes soil bacterial community structure in this model for the improvement of planting and breeding technology and realization of ecological regulation. The community structure of soil microorganisms was compared between two models of rice-frog (black-spotted pond frog; Pelophylax nigromaculatus Hallowell, 1861) co-cropping (DW) and rice monoculture (DD) at tillering stage, full heading stage and maturity stage, to accumulate data for research on ecology of rice-frog integrated farming and provide a theoretical basis for optimization of this production technology. Main bacterial phyla occurring in rhizosphere soil of rice fields in both models under three stages were Proteobacteria, Chloroflexi, Acidobacteriota, Bacteroidota, Firmicutes, Actinobacteriota, Nitrospirota and Desulfobacterota. Compared to DD, DW group had more Actinobacteriota in the dominant phyla at maturity and less Desulfobacterota throughout the growth period. The main dominant genera were norank_f_Anaerolineaceae, norank_f_norank_o_norank_c_Thermodesulfovibrionia, norank_f_norank_o_SBR1031, norank_f_norank_o_Vicinamibacterales, unclassified_k_norank_d_Bacteria and Thiobacillus. There were five categories with significant difference, norank_f_Anaerolineaceae, norank_f_norank_o_SBR1031, norank_f__norank_o_Vicinamibacterales, Thiobacillus and unclassified_k_norank_d_Bacteria; all were higher in relative abundance in DW than in DD group. It indicates that rice-frog crop model promotes the growth of these five types of bacteria, which have a boosting effect on rice growth. The bacterial Chao index and Shannon index of rhizosphere soil of rice field increased after introduction of frog in DW group. The two models showed less variation in soil bacterial community structure in root system from full heading to maturity stage, and co-cropping model showed less variation compared to rice monoculture.