| In order to screen out aquatic economic animal species suitable for comprehensive cultivation and cultivation of rice and fish in cold regions(high latitudes)and good returns in a short period of time.And based on this,a set of integrated rice and fish breeding and breeding models suitable for saline and alkaline land in cold regions was designed,which promotes the adjustment of the structure and method of breeding species in northern ponds,and achieve the goal of improving the quality and efficiency of aquaculture in cold regions.In this paper,the climate characteristics of Heilongjiang Province and the environmental conditions of saline-alkali rice fields are used as the experimental background."Taihu No.2" shrimp(Macrobrachium nipponense)(freshwater shrimp)and "Yangyu No.1" spine-tailed white shrimp [Palaemon(Exopalaemon)carinicaud](sea shrimp)were selected as experimental materials.Tolerance studies were conducted on adverse environmental factors such as low temperature,salinity,and carbonate alkalinity.Meanwhile,Prawns were reared experimentally in saline-alkali paddy fields in cold regions.The research not only provides theoretical support for the safe cultivation of high-quality aquatic species such as prawns and white tail prawns in saline-alkali water ponds and paddy fields in cold regions,but also provides a strong foundation for the establishment of comprehensive breeding models for prawns in saline-alkali land in cold regions data support.The research results have important demonstration significance and practical value for promoting the establishment and promotion of comprehensive paddy planting,breeding models in high latitude regions of China,improving the comprehensive utilization of land resources in a low-yielding country,saline region,and driving regional economic growth.The main contents are as follows:1.The single-factor static acute toxicity test was used to study the carbonate alkalinity and low temperature of "Taihu No.2" shrimp with an average body length(2.76 ± 0.66)cm and a body weight(0.26 ± 0.22)g Tolerance.Twenty shrimps were placed in a 42.6cm × 28.4cm × 28.4cm cuboid transparent aquarium,and the carbonate alkalinity in the experimental water was gradually adjusted from low to high to 12mmol/L,14mmol/L,16mmol/L,18mmol/L and 20mmol/L.There are 5 gradients.Each carbonate alkalinity gradient and the control group are set up in triplicate.The low temperature experiment was performed in a 24.8cm × 17.8cm × 9.8cm rectangular plastic water tank in a fluorine-free environment-friendly biochemical incubator,and the water temperature gradually decreased to 10 °C,9 °C,8 °C,7 °C,6 °C,5 °C.There are 6 gradients,three replicates for each temperature setting,and a control group with water temperature at 20-25 °C.The results showed that when the water temperature was(23.1 ± 1.48)°C,p H = 8.9 ± 0.30,salinity was 0.62 ‰ ± 0.27 ‰,and dissolved oxygen was(7.2 ± 0.30)mg/L,The alkalinity(LC50)values of the prawns were at 12 h,24h,48 h.72h,and 96 h were 27.66mmol/L,26.94mmol/L,22.51mmol/L,15.00mmol/L and 14.42mmol/L,and the safety value was 4.71mmol/L.At p H = 7.75 ± 0.12 and dissolved oxygen at(7.84 ± 0.97)mg/L,the semi-lethal low temperature(LT50)of prawn in 12 h was 6.702 °C.This study provides basic data for the establishment of a saline-alkali water prawn farming model in cold regions.2.The single-factor static acute toxicity experiment was used to study the " Huangyu No.1" spinal tail white shrimp with an average body length of(2.74 ± 0.5)cm and an average body weight of(0.15 ± 0.07)g at low salinity and high carbonic acid.Survivability in a salinity environment.The results showed that the survival rate of white tail prawns was not significantly reduced within 24 hours when the salinity was 3 ‰ to 1.5 ‰;when the salinity was less than 1.5 ‰,the survival rate was significantly reduced within 24h;the salinity was maintained at 0.5 ‰ After 96 h,the survival rate was only 5%.The s alinity of the water body in the selected saline-alkali land of the experiment was 0.34 ‰ ± 0.02 ‰,which could not meet the normal survival needs of white tail prawns.When the salinity of the white tail prawn is 3.5 ‰ and the carbonate alkalinity is less than 5.0 mmol/L,the survival rate does not decrease significantly within 24 hours;when the carbonate alkalinity is higher than 5 mmol/L,the white tail prawn is at 24 h The survival rate of the experimental shrimp was significantly reduced;the survival rate of the experimental shrimp was only 4% after the carbonate alkalinity was maintained at 11 mmol/L for 48 h.To sum up,the white tail prawns cannot survive normally in cold saline water with salinity lower than 5 ‰ and carbonate alkalinity higher than 5mmol/L.3.Northeast China has abundant saline-alkali water(land)resources.In order to increase the utilization rate of saline-alkali water(land)resources and fisheries,it will drive regional economic growth.Based on the geographical,climate and environmental characteristics of Heilongjiang Province,this project selects prawns with high economic value and short breeding cycle as breeding objects.Based on the living habits of prawns and the standards of China’s comprehensive rice and fish breeding industry,the paper researches that is carried out from field engineering,selection of rice varieties,planting management,and prawn growth.This time,3,000,4500,and 6,000 "Taihu No.2" shrimp seedlings were put on 1 #,2 #,and 3 # rice paddies to conduct 60 d rice and shrimp breeding experiments.The results show that the U-shaped field project adopted this time can meet the rice and shrimp production while ensuring rice yield and improving rice quality.From the survival rate of each group of prawns,the survival rate of 3,000 rice per 667m2 of rice field,the highest rate was followed by 4500 tails,and the survival rate was the lowest when 6000 tails were stocked per 667m2.From the relative weight gain rate and specific growth rate of each group of prawns,the relative weight gain rate and the specific growth rate was also higher than the two groups with higher stocking density.To sum up,it is very promising to carry out a comprehensive breeding model of rice and shrimp in cold and saline land. |
