| In this study,rice-carp coculture paddy field(RF)was the trial group and ricemonoculture(RF)was the control group respectively.The physiochemical indexes in water and sediment of two system were determined and analysed by the ecological methods.At the same time,the species and abundance of planktons and bacteria in the water of two systems were identified and analyzed.In order to elucidate the differences in energy flow and nutrient structure between the two ecosystems,the flow of materials and energy and the characteristics of system structure were analysed by the model of Ecopath.In addition,to investigate the difference of nutrition of the same fish species fed in paddy field and in pond,the contents of nutritional components and the texture of meat were measured by biochemical methods,The results are as follows:The physicochemical indexes of water and sediment of two kinds of paddy fields were determined and analyzed,the results show that the electrical conductivity(Cond)and total dissolved solids(TDS)of water in the trial group were significantly lower than those in the control group(P < 0.05),and the content of nitrate and total nitrogen were significantly lower than those in control group(P < 0.05),and the contents of total phosphorus(TP)in sediment in the trial group were significantly higher than those in the control group(P < 0.05).The phytoplankton and zooplankton in trial group and control group were identified and analyzed.The results showed that: there were 18 species of phytoplankton in 7 phylum species in trial group and 24 species of phytoplankton in 5 phylum in control group,and The trial group enriched with the species of Pyrrophyta and Chrysophyta were found in trial group not in control group.In addition,the density and biomass of phytoplankton in the trial group were significantly higher than those in the control group(P < 0.05).The mainly dominant species in trial group were in the phylum of Chlorophyta and Bacillariophyta,and in control group were in the phylum of Cyanophyta and Bacillariophyta respectively.There were 11 species of zooplankton in the trial group and in the control group,and the density and biomass of zooplankton in the trial group were significantly higher than those in the control group(P < 0.05).The results of the experiments on the bacterial community structure of the two systems showed that the Shannon diversity index in the trial group was extremely significantly higher than that in the control group(P < 0.05).The absolute abundance of Actinobacteria in the experimental group was significantly higher than that of the control group(P < 0.05),and the absolute abundance of Bacteroidetes and Firmicutes was significantly lower than that of the control group(P < 0.05),and Proteobacteria were abundant in both groups.The analysis of energy flow in the two ecosystems by the Ecopath model showed that the ecological nutrient efficiency of Water spider,field snail(Viviparidae),rotifer and sediment debris were higher than the control group,and most of the energy flow in the two systems in the first and second trophic level but the trial group had a higher utilization rate of clastic.The ratio of total primary production to total respiration(TPP/TR)and the ratio of total primary productivity to total biomass(TPP/TB)in the trial group were lower than those in the control group,and the index of system connectivity(CI)and Finn's cycle index(FCI)were both higher than the control group.The results showed that compared with control group,the trial group had higher energy utilization rate,maturity and stability.The nutrition components and texture properties of rice flower carp(Cyprinus carpio)and common carp were determined and analyzed,the results showed that The content of ash,calcium and phosphorous in rice flower carp are significantly higher than those in common carp(P < 0.05),and the content of zinc in rice flower carp is extremely significantly higher than that in the latter(P < 0.01).The fat content in rice flower carp is significantly lower than that in the common carp(P < 0.05),and there is no significant difference in the contents of protein,moisture and iron between the two groups(P > 0.05).In both of the two groups,16 kinds of amino acids were detected,and the total amino acids(TAA)were 16.85% and 16.55%,respectively.22 kinds of fatty acids were detected in the meat of common carp and 21 in rice flower carp,and there is no significant difference in the content of saturated fatty acid(SFA),monounsaturated fatty acid(MUFA),n-3 polyunsaturated fatty acid(n-3 PUFA)between the two groups(P > 0.05).The results of texture analysis show that the hardness,chewiness and gumminess index of the meat of rice flower carp were significantly higher than those of common carp.The composition of fatty acids and amino acids in meat of the two groups are of no significant difference,and they can also provide high quality protein.Furthermore,the meat of rice flower carp has the features of high-minerals,low-fat and good-tasting.In the study,it was found that the water quality indexes of paddy field with carp were improved compared with those of rice-monoculture paddy field,and the density of plankton is higher,and the species composition of plankton is more sound than the latter.The traits of structure of bacterioplankton community of two groups are quite different.Furthermore,compared with pond culture,the meat quality of carp raised in paddy field was improved.In consequence,the mode of rice-fish-coculture is worth popularizing and its internal mechanism needs further study. |
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