| Ecologically speaking,the comprehensive cultivation of rice and fish is a symbiotic ecosystem dominated by rice and fish(shrimp,crab,etc.)after the introduction of fish(shrimp,crab,etc.)into the paddy ecosystem.Heilongjiang Province is located in the alpine area,the growth cycle of aquatic animals in rice fields is short,and there are few species suitable for breeding.In t HSI study,the changes of production performance,environmental parameters and system nitrogen and phosphorus budget of farming objects were studied in order to elucidate the operation mechanism of rice-fishing comprehensive cultivation model in cold areas.it also provides some important technical parameters for perfecting the rice-crab cocropping model in cold regions.The specific results are as follows:1.Comparative study on different comprehensive planting and breeding models of rice and fishery in cold region.Fifteen rice field units with an area of 300m2 were set up in the national ricefishing comprehensive cultivation demonstration area of Suihua City,Heilongjiang Province.A comparative study was conducted by using rice-crab co-cropping model(RC),rice-fish co-cropping model(RF),rice-loach co-cropping model(RL),ricecrab-loach co-cropping model(RCL)and rice monoculture model(CK).The specific results are as follows:(1)The rice yield of RCL model was significantly higher than that of RL model and CK model.The WGR and SGR of river crab in RCL model were significantly higher than those in RC model.The order of economic benefits in the co-operation model is as follows: RCL > RC > RF >RL > CK.(2)During the experiment,the variation range of paddy field water temperature in each group was 17.0 ~ 26.0 ℃.The value of p H fluctuates from 6.5 to 8.0.In August,the DO value of each group was the lowest,and the water do value of CK group was significantly higher than that of treatment group at many time points.The change trend of NO3-N content in each group was basically the same,which was at a high level in the early stage of culture,decreased significantly in July,and gradually stabilized between 0~0.30 mg/L at the end of July.The contents of TAN,TIN,NH3-N and TN in paddy water of all groups had the same change trend,which in the early stage of culture was significantly higher than that in the later stage of culture,and all the parameters remained at a low level at the end of June.The content of total phosphorus in paddy water of all groups increased at first and then decreased during the experiment,and the content of TP in RCL group was higher than that in other groups.The content of COD in CK group was always higher than that in treatment group.A total of 61 species,7 phyla and 38 genera of phytoplankton were detected in 5 models.The density and biomass of phytoplankton in RCL group were significantly higher than those in CK,RC and RL groups.(3)The dominant bacteria in the paddy soil of each group were the same,but the abundance was quite different.There were significant differences in the relative abundance of actinomycetes and Proteus among different modes.(4)The net profit of rice,crab and Misgurnus anguillicaudatus was the highest in the above co-cropping model.Fertilizer and feed are the main ways of nitrogen and phosphorus input in the breeding system,and rice and farmed animals are important ways of nitrogen and phosphorus output.The nitrogen and phosphorus input and output of the co-cropping model were higher than those of the monoculture model,and the nitrogen and phosphorus output of the co-cropping mode was also higher than that of the monoculture model.2.Effects of different stocking density of river crab on comprehensive production performance and environmental factors of rice crab in cold region.In this experiment,with rice sheet as control,ecological methods were used to study the effects of different stocking densities of river crabs(200,350,500,650 and800 / mu)on the growth performance of river crabs and rice,as well as the water quality and sediment of rice fields in cold regions.The results showed that:(1)With the increase of stocking density,the WGR,SGR,GSI,MY index and TEY index of river crab decreased significantly.The seed setting rate and yield of rice in 350 ind /mu treatment group were significantly higher than those in other groups.(2)with the increase of stocking density of river crab,the content of TP in soil of each treatment group increased gradually.The contents of TN and TP in soil of 800 ind / mu treatment group were significantly higher than those of 350 ind / mu and 500 ind / mu treatment group.(3)During the experiment,the temperature of each group varied from 17.0 ℃ to 26.0 ℃.The p H value of water in each treatment group decreased at first and then increased.The DO content of all groups was at a low level in the high temperature season in August,and the DO value of each treatment group was significantly lower than that of rice monoculture group on July 5th and August 3rd.The contents of TAN,TIN,NH3-N and TN in paddy water of all groups showed the same trend during the experiment,and the parameters in the early stage of culture were significantly higher than those in the later stage of culture.The COD content in paddy field water of 200 ind / mu and 350 ind / mu treatments was significantly lower than that of rice monoculture group at several sampling sites.The results of comprehensive analysis of various parameters showed that the best stocking density of buckle crab in the process of comprehensive cultivation of rice crab in cold region was 350 ind / mu.3.Effects of different feeding levels on comprehensive breeding performance and water quality of rice crab in cold regionIn this experiment,rice sheet was used as control to study the effects of different feeding levels(1.5% and 3%)on the growth performance of river crab and rice and the physical and chemical factors of rice field water quality in cold region.The results showed that there was no significant difference in rice yield among all groups.There was no significant difference in WGR,SGR,GSI index,HSI index,MY index,TEY index and tissue nutritional composition between the two groups.There was no significant difference in the contents of TP,TN and TC in paddy soil among different groups.During the experiment,the fluctuation trend of water temperature in each group was the same,which was between 17.0 ℃ and 26.0 ℃.The p H of paddy field water in the treatment group decreased at first and then increased,with a fluctuation range of 6.7 to 7.4.The DO value and COD content of the two treatment groups were significantly lower than those of the rice monoculture group at many time points.The contents of TAN,NO3-N,TIN,NH3-N and TN in paddy water of all groups showed the same change trend,and decreased significantly from the higher level in the early stage of culture,and all the parameters remained at a low level by the end of June.During the experiment,the water quality parameters of the two treatment groups were similar.According to the comprehensive analysis of various parameters,under the rice-crab co-cropping mode in cold regions,1.5% of the compound feed level in the process of planting and breeding can meet the normal nutritional needs of river crabs.4.A comparative study on the co-cropping of Liaohe river crab and Changjiang river crab and rice in cold region.In this experiment,rice sheet was used as control,and the effects of two kinds of river crabs on the growth performance of rice and river crab and the physical and chemical factors of rice field sediment and water quality in cold region were studied through the comparative experiment on the co-cropping of Liaohe river crab and Changjiang river crab and rice in cold region.The results showed that there was no significant difference in rice yield among all groups.The results showed that there were no significant changes in WGR,SGR,HSI,GSI,MY index and TEY index of river crab under the two modes.There was no significant difference in the contents of TP,TN and TC in paddy soil among different groups.During the experiment,the fluctuation trend of water temperature in paddy field was the same in each group.The p H of rice monoculture group showed a downward trend as a whole,while the p H of the two treatments decreased at first and then increased.The DO value of rice monoculture group decreased gradually,and it was significantly higher than that of treatment group except July 15.The NO3-N content of rice monoculture group increased at first,then decreased and then increased,while the NO3-N content of the two treatments increased at first and then decreased as a whole.During the experiment,the contents of TAN,TIN,NH3-N and TN in paddy water of each group showed the same trend,decreased significantly from the higher level in the early stage of culturel.In the middle and later stage of culture,the COD content in paddy field in treatment group was significantly lower than that in rice monoculture group.During the experiment,the water quality parameters of the two treatment groups were similar.The results of comprehensive analysis of various parameters showed that the culture situation of Liaohe crab was similar to that of Changjiang River crab in the stage of rice field culture in cold region. |
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