Impacts of co-culture of rice and aquatic animals on rice yield and quality: A meta-analysis of field trials

As an eco-agricultural model, the co-culture of rice (Oryza sativa) and aquatic animals (CRAA) is an efficient approach to utilize the land and water resources for growing the grains and aquatic animals. However, the impacts of CRAA on rice yield and quality remain controversial in actual field conditions. To respond these issues, we conducted a meta-analysis on 456 paired-treatment datasets collected from 129 field research publications that compared rice yield and quality in rice monoculture and CRAA. Overall, the results indicated a significant contribution of CRAA to improve rice yield and quality (P < 0.05). However, the effects varied under different co-culture modes, environmental factors, and agricultural management practices. In accordance, the coculture of rice with fish or waterfowl had the greatest benefits for both rice yield and quality. Our results revealed that CRAA application in subtropical regions caused the highest increases in rice yield and quality (P < 0.05). Furthermore, we found that paddy soils with low nitrogen provide a better platform for rice cultivation under CRAA. The yield of indica subspecies was substantially higher than that of japonica under CRAA treatments (P < 0.05). Of all fertilization schemes, the combined application of organic and inorganic fertilizers had the greatest impact on rice yield and quality. The effect sizes of the proportion of head rice (r = 0.386, P < 0.05) and gel consistency (r = 0.401, P < 0.05) had significant correlations with that of CRAA on rice yield. In conclusion, our findings suggest that CRAA can be a potential practice to effectively improve both rice yield and quality. In particular, the co-culture of indica rice with fish or waterfowl receiving both organic and inorganic fertilizers in paddy soils with low total nitrogen content (TN <= 1.5 g/kg) in humid areas is the most promising strategy to simultaneously achieve the highest rice yield and quality.