| Rice-fish farming is a green circular agricultural model that combines rice cultivation with aquaculture to realize the mutually beneficial symbiosis of rice and fish and is one of the ways to improve the utilization of saline-alkali land.At present,domestic and foreign experimental and comparative research on rice-fish farming are mainly focused on the characteristics of growth and reproductive yield of rice and cultured organisms on common loam,physical and chemical properties of breeding water bodies,and breeding techniques.There is little research on the physiological development characteristics and nutrient characteristics of rice under these conditions.The purpose of this study was to further explore the practical effects of rice co-farming in low-lying saline areas,and to further clarify the direct effects of rice co-farming in low-lying saline areas on rice growth,so as to provide theoretical basis for the safe,high-quality and high-yield cultivation of rice in low-lying saline areas and the promotion of improved utilization in saline areas.In 2018 and 2019,the experiment was conducted in Lanfeng village,Changxin Township,Helan County,Ningxia Yellow River Diversion Irrigation Area and Junhua farmers’ Professional Cooperative in Xixia District,Yinchuan City,respectively.The comparative study was carried out on the growth and development,photosynthesis,physiological characteristics,nutrient characteristics,yield and quality of rice,soil characteristics,ecological effect under the mode of rice fish co cropping and the mode of conventional rice co cropping research,and analyze the energy flow,logistics,and value flow of the two ecosystems.The results show that:1.Rice-fish farming in low-lying saline-alkali areas is conducive to the growth and development of rice.Compared with conventional rice cultivation,rice plant height and dry matter weight have increased significantly to varying degrees during the full growth of rice,which increased by 1.77%～6.76%,1.86%～21.48%.The leaf area of leaves was larger than that of conventional rice at the booting stage and the filling stage.2.The rice-fish farming system in low-lying saline-alkali areas has certain effects on the physiological characteristics of rice at various growth stages.1)Under the condition of co-cropping,the photosynthetic capacity of rice was significantly improved to a certain extent,which was expressed as the main photosynthetic capacity of rice leaves(Pn,Gs,Ci,Tr)and SPAD values were significantly higher than those of conventional rice,increased by 0.82%～12.73%,2.16%～12.51%,1.32%～45.42%,1.72%～11.76%,3.43%～12.88%,respectively.The fluorescence parameter values(F0,Fm,Fv/Fm,Fv/F0,PI)of the leaves are higher than those of conventional rice,but the difference is not significant;2)Rice Co-fishing enhanced the stress resistance of rice in saline-alkali areas,and changed the osmolyte and antioxidant protective enzyme activities of rice leaves,which were expressed as SOD(superoxide dismutase)and POD(peroxide),CAT(catalase)activity,and soluble sugar content were increased to varying degrees from conventional rice crops during the seedling-homogeneous stage,which increased by 5.09%～39.14%、4.55%～37.78%、6.59%～31.95%、1.43%～10.70%,respectively,and the contents of Pro(proline)and MDA(malondialdehyde)in leaves decreased by 6.95%～32.56%and 2.04%～24.84%,respectively.3.Rice-fish farming is beneficial to promote nutrient absorption of rice.During the jointing-milk maturity period,the accumulated N、P and K absorption in the above-ground rice of the co-planted rice plants were significantly higher than those of the conventional rice,which increased by 57.51%to 80.83%,41.16%to 55.26%,and 8.50%to 25.02%,respectively.4.Rice-fish farming in low-lying saline-alkali areas is beneficial to the improvement of soil environment.Compared with conventional rice production,rice fishing reduced pH in saline soil and improved the organic matter,total nitrogen,total phosphorus,total potassium,ammonia nitrogen and effective phosphorus content of the soil during the fertility period.The pH of the rice in the co-cropped rice decreased by 0.47%to 2.63%compared to the conventional rice,and the contents of soil organic matter,total nitrogen,total phosphorus,total potassium,ammonia nitrogen and effective phosphorus content were increased by 8.14%～15.42%、3.31%～10.47%、1.90%～16.34%、3.65%～17.83%、5.19%～21.10%、2.39%～14.76%.5.Co-cropping of rice and fish in low-lying saline-alkali areas is conducive to increasing rice yield and improving rice quality.1)The number of panicles and thousand-grain weight of the rice-fish-cropping system was significantly higher than that of conventional rice,which increased by 14.36%to 16.72%and 3.78%to 6.21%,respectively.There was no significant difference between the number of panicles and conventional rice;2)Under the intercropping mode,the plant height,dry matter weight,photosynthetic parameters Pn,Gs,etc.of rice at each stage have a positive correlation with yield,and most of them have significant or extremely significant relationships;3)Milling quality,appearance quality,nutritional quality,taste quality,and physical properties related to cooking taste quality of co-cultivated rice are improved to different degrees compared with conventional rice.Compared with conventional rice,the brown rice rate,milled rice rate,head rice rate,protein content,lysine content,taste value and gel consistency of rice in rice fishery co cropping system increased by 1.30%～2.91%、3.12%～3.55%、3.52%～4.69%、10.14%～14.09%、6.25%～16.86%、5.29%～11.24%、2.42%-4.78%respectively,and the chalkiness,chalkiness grain rate and amylose content decreased by 9.32%～16.14%,8.94%～16.14%and 3.31%～3.69%,respectively.6.The productivity of the rice-fish farming system in low-lying saline-alkali land has improved,and the ecological effect is better.Compared with conventional rice,the energy flow,material flow and value abortion investment ratio of co-cropping rice are increased,economic profit increased by 34.85%～61.94%,the productivity level is higher,and the application of chemical fertilizer and pesticide in the system is reduced... |
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