Preliminary Research And Application Of The Coupling Model Of "Rice-crayfish Rotation + Rice-crab Co-culture"

The traditional rice planting model is relatively low-efficiency,which seriously affects the enthusiasm of farmers to plant rice.In some areas,the rice fields are abandoned,"non-agricultural" and "non-grain" and other problems.In addition,the large amount of chemical fertilizers and pesticides used in traditional rice cultivation has caused the problem of agricultural non-point source pollution.Therefore,it is of great practical significance to actively explore the rice-fishing integrated farming technology of "promoting rice by fishing,stabilizing grain and increasing efficiency,quality and safety,and ecological environmental protection".Ricefishing integrated farming in East China is dominated by the "rice-crayfish rotation" model.This model usually has shortcomings such as paddy breeding,lack of co-culture between rice and crayfish,and difficulty in controlling the density of crayfish seedlings;The rice-crab co-culture model has the advantages of mutual benefit of rice and crab,no reduction of rice production and reduction of pesticides and fertilizers.It has been popularized and applied on a large scale in Panjin area,but due to reasons such as rice stubble and high temperature in summer,the co-culture model of rice and crab in East China is less developed.In view of this,this study carried out the research and optimization of the "rice-crayfish rotation + rice-crab co-culture " coupling technology and rice-crab feeding mode in East China,in order to provide practical basis and basic data for the development of rice-fishing in East China.1."Crayfish-rice-crab" coupled cultivation technology experiment in East ChinaIn order to explore the feasibility of the "crayfish-rice-crab" coupled breeding model in East China,this experiment was carried out in the research center of Shanghai Ocean University in Honglin Town,Xuanzhou District,Xuancheng City,Anhui Province from January 2021 to November 2021.The results showed:(1)The peak baiting periods of crayfish and crab were from April 22 to May 13 and August 7 to September 7,respectively.The fishing peaks of crayfish and crab mainly occurred at the end of May and the beginning of November;(2)Under the condition of rice-crab co-culture,the total growth period of rice is 159 days,and the rice yield is 357kg/667 m~2 according to the overall area,and 510 kg/667 m~2 according to the pure-bred rice area;(3)The yield and survival rate of crayfish farming were higher than those of crab farming,and the FCR(2.21)during crayfish farming was lower than that of crab farming in paddy fields(3.03).The total investment and total profit of the rice-crayfish-crab coupling model are 5134 yuan/667 m~2 and 1966 yuan/667 m~2respectively.The cost is mainly concentrated in feed,seed,rent and depreciation of land facilities.The economic benefits of crayfish farming are slightly higher than crab farming.In conclusion,it is feasible to carry out rice-crayfish-crab coupling model in East China.On the basis of ensuring the yield of rice,we can make full use of the paddy space to breed some juvenile crabs,and improve the economic and ecological value of the paddy system.2.Effects of two feeding modes on the culture performance and physiological metabolism of juvenile Chinese mitten crab(Eriocheir sinensis)reared in the rice field In order to optimize the feeding mode for the juvenile Chinese mitten crab Eriocheir sinensis reared in rice-field.Compound diets and traditional diets(soybean meal,bran,corn and wheat)were fed to juvenile E.sinensis cultured in rice field for 152 days.Each feeding group had 3 replicates.This study was conducted to investigate the effects of two feeding modes on culture performance,protein metabolism,digestive enzymes,antioxidant and immune indexes of juvenile crabs.The results showed that:(1)From July to November,the body weights of female and male crabs from the compound diet group were higher than those in the traditional diet group,but the differences were not significant(P > 0.05);(2)In terms of culture performance,the average body weight of normal juvenile crabs and its yield,the average body weight of 1-year-old precocious crab and its yield,the total yield and the survival rate of the compound diet group were slightly higher than those of the traditional diet group.And the feed conversion ratio was much lower than that of the traditional bait group(P< 0.05);(3)In terms of protein metabolism,the contents of total protein in the hemolymph of female and male crabs fed the compound diet was significantly higher than that in the traditional diet group(P < 0.05),while the contents of urea nitrogen in the hemolymph of male crabs and the activity of glutamic oxaloacetic transaminase in the hepatopancreas of the traditional diet group were significantly higher than those of the compound diet group(P < 0.05);(4)Lipase in the hepatopancreas of female and male crabs in the compound feed group was significantly higher than that in the traditional diet group(P < 0.05),while the α-amylase activity of the male crabs in the compound diet group was significantly lower than that of the traditional diet group;(5)The total antioxidant capacity,alkaline phosphatase,acid phosphatase activities in the hemolymph of female crabs and acid phosphatase activity in the hepatopancreas of the compound diet group were significantly higher than those of the traditional feed group(P < 0.05).In conclusion,feeding compound diet can improve the culture performance,promote protein deposition and lipid absorption,enhance the antioxidant and immune capacity of juvenile E.sinensis reared in the rice field,which then result in the improvement of the quality of crab seed.