| At present,driven by profits of breeding,some farmers placed more attention on fish breeding than rice planting.Ditch area made up over 20%of the total paddy area,damaging the paddy structure and causing a heavy loss of the rice cultivation area.In addition,global climate change and frequent outbreak of extreme weather had led to more uneven distribution of seasonal rainfall and more short time rainstorm and torrential rain.Efficient irrigation water had become a major issue in rice cultivation.At the same time,the increase of rice yield still relied on the heavy use of chemical fertilizer and pesticide,which featured low efficacy and increased the surface source pollution.In order to solve the present problem in rice production,the author summarized previous researches on rice-fish cultivation and ridge cultivation and came up with a new mode in this research that combined rice ridge cultivation with rice-fish-chicken farming.The rice yield and yield formation,the growth characteristics of the overground community,the root system and the stalk,the physiological characteristics of the flag leaf,the physio-chemical characteristics of the soil,the activity of the soil enzyme,the water body quality and the bio-diversity were studied to see the yield formation and the ecological effect under rice-fish-chicken ridge cultivation.The results could also serve as the theoretical basis for the application of this mode.Here were the results:(1)Compared with conventional rice ridge cultivation(CK),rice-fish-chicken ridge cultivation(RFC)and rice-chicken ridge cultivation(RC)had more stable yield in the two years.The yield of rice-fish ridge cultivation(RF)was 29.98%lower on average.As to the yield formation,RFC and RC did not see significant differences in terms of the number of the average productive panicle,grain number per panicle,maturing rate,and 1000-grain weight.In RF,the number of the average productive panicle,grain number per panicle,maturing rate,and 1000-grain weight dropped significantly by 19.70%,4.84%,3.99%and5.74%respectively.The two-year results showed that compared with CK,RFC and RC had lower peak value of the tiller in the middle and late stage.Ineffective tiller was thus reduced.The tiller number of RF was significantly lower compared with that of CK.The amount of the average accumulated dry matter in the stem,leaf and spike was not significantly different among RFC,RC and CK,which was nonetheless significantly higher than that of RF.RFC,RC and CK also had higher community growth rate,net assimilation rate and photosynthetic potential,which ensured more accumulated dry matter and higher yield.In addition,RFC and RC were more able to develop strong stems and improve lodging resistance as they saw higher stem internode diameter and wall thickness,higher stem breaking resistance and cross-section modulus,and lower stem maximum bending stress and lodging index.(2)Compared with CK,RFC and RC had higher amount of root shoot ratio,root volume,root number,maximum root length,root oxidation activity and bleeding sap after full heading.In RF,these indexes were lower than those of CK.The amount of root dry matter,root volume,root oxidation activity,and root bleeding sap was 40.72%,33.00%,15.63%and 31.41%lower respectively.The amount of soluble sugar,protein,and amino acid in 2019 was 18.47%,39.32%and 32.50%lower respectively.(3)Compared with CK,RFC and RC had higher SPAD value and chlorophyll a and chlorophyll b amount in the flag leaf after full heading.The soluble sugar amount of RFC and RC was 1.98%and 1.87%higher on average respectively,that of protein,11.85%and8.89%.The activity of POD,SOD,and CAT of the flag leaf was higher.Malonaldehyde amount was 5.30%and 5.19%lower respectively.Fv/Fm in the chlorophyll fluorescence was higher.These conditions helped slow down the aging of the flag leaf,increase the flag leaf's net photosynthetic rate and promote the accumulation of dry matter after full heading.Compared with CK,RF had lower flag leaf's SPAD value,chlorophyll a and chlorophyll b amount,protein amount,and soluble sugar amount,higher malonaldehyde amount,and lower SOD,POD,and CAT activity,speeding up the aging of the flag leaf,slowing down its photosynthetic rate,and causing a further drop of the dry matter's amount after heading.(4)Compared with CK,RFC and RC reduced the soil bulk density of in the maturing stage and increased the soil porosity,which ensured stability of the soil aggregate and improved the soil's compactness,air permeability,and structure.RF performed worse than RFC and RC in upgrading the soil's physical structure.As to the chemical characteristics of the soil,compared with CK,RFC and RC saw higher amount of total N,total K,alkaline hydrolysis N,rapidly available P,rapidly available K and organic matters in the soil after maturing stage.The soil's p H was 3.93%and 4.46%lower respectively.The amount of total N,total K,alkaline hydrolysis N,rapidly available P,rapidly available K and organic matters in RF after maturing stage was higher than that in CK,but was lower than that in RFC and RC.The soil's p H of RF was higher than that of RFC and RC.Compared with CK,RFC and RC had an increase of the enzyme activity from tiller stage to maturing stage.The increase of the activity of urease,phosphatase,protease,dehydrogenase,and sucrase were more noticeable,that was,38.67%and 36.00%for urease,28.94%and 29.92%for phosphatase,26.70%and 23.92%for protease,17.83%and 16.98%for dehydrogenase,and 40.84%and39.30%for sucrase,all reaching significant differences in all stages except the tiller stage.The activity of the enzyme in RF also increased,but not at a remarkable rate.(5)The average surface water p H of RFC,RC,RF and CK in 2019 was 7.48,7.45,7.57 and 7.68 respectively.The surface water in RC and CK had higher amount of dissolved oxygen,which was noticeably higher than 6.37 mg/L in RFC and 6.07 mg/L in RF.Compared with CK,RFC,RC and RF saw higher amount of NH4~+,NO3~-,total N,dissolved P and total P in the water.The average increase of the amount of NH4~+was 27.96%,29.03%,and 8.60%respectively,that of total N,25.44%,26.87%,and 11.21%,and that of dissolved P,14.57%,12.85%,and 2.26%.(6)The study on diseases,pests and weeds,and soil microorganism in different modes showed that RFC,RC and CK could effectively control weed density.Compared with RF,RFC,RC and CK realized a respective 94.02%,92.37%and 84.89%control at maturing stage,with a drop of the species diversity,Shannon-Wiener index,and Simpon index and an increase of the Pielou index.It indicated that RF changed the formation and diversity of weeds without an effective control over them.During the two years,RFC,RC and CK could better control cnaphalocrocis medinalis,chilo suppressalis,and sheath blight.The morbidity rate of cnaphalocrocis medinalis was 4.97%,4.86%and 4.37%lower respectively,that of chilo suppressalis,2.80%,2.56%and 3.61%,and that of sheath blight,12.63%,12.26%and9.25%.In 2019,RFC and RC realized an increase of the richness and diversity of the microorganism community at 0?20 cm soil.Proteobacteria was the dominant bacteria.RFC and RC also had higher community structure similarity that differed from that of RF and CK.(7)To sum up,chicken breeding,fish breeding,and breeding of chicken and fish under rice ridge cultivation were new modes of ecological cultivation in the paddy field.These modes made better use of the water and field and produced rice,fish,and chicken at the same time.They were of great significance to green and sustainable development of agriculture.Thanks to the activities of chicken and fish and the feces excreted,rice-fish-chicken ridge cultivation and rice-chicken ridge cultivation effectively controlled weeds,improved the soil structure,raised the level of soil enzyme activity and fertility level,and reduced the risk of eutrophication in water.They helped improve the structure of the root morphology,stabilize rice tillers,accumulate more dry matter,strengthen the lodging resistance,maintain the flag leaf chlorophyll,soluble matter content and protective enzyme activity at a higher level,and improve photosynthetic capacity.The rice yield was therefore guaranteed.In comparison,rice-fish ridge cultivation was affected by weeds,diseases and insect pests.The growth of the root and the overground part of the rice was seriously inhibited,resulting in a remarkable reduction of yield.Therefore,in practical production,the promotion value of rice-fish-chicken ridge cultivation and rice-chicken ridge cultivation was higher than that of rice-fish ridge cultivation. |
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