| In order to clarify the effects of fertilization patterns,water-fertilizer coupling,water-fertilizer-air-heat regulation on rice-crab symbiosis in Helan County,Ningxia,China,comparative and orthogonal experiments were conducted,the effects of fertilization mode,water-fertilizer coupling and water-fertilizer-air-heat comprehensive regulation on the growth,physiology,yield and quality of rice-crab under the condition of rice-crab symbiosis were studied systematically,a fertilization model,a water-fertilizer coupling model and a water-fertilizer-air-heat regulation model suitable for the rice-crab symbiosis in the Helan region of Ningxia were established.The results can provide a theoretical basis for the standardization of the rice-crab industry in the region,it is of great significance to improve the quality and efficiency of rice-crab symbiosis model in modern ecological irrigation area of Ningxia.The main results are as follows:(1)The field experiment was carried out by using two factors(cultivation mode Z and Fertilizer Application Mode F)at two levels(cultivation mode Z1 and rice single cropping Z2,Fertilizer Application Mode F1 and F2 combined with bacterial residue organic fertilizer and compound fertilizer respectively),the effects of cultivation and fertilization on growth,photosynthesis,yield and quality of rice crab were studied.The results showed that fertilization had significant effects on plant height,stem diameter,chlorophyll content,stomatal conductance Gs,intercellular carbon dioxide concentration Ci,transpiration rate Tr,net photosynthetic rate Pn and rice yield.The plant height,stem diameter,net photosynthetic rate,stomatal conductance,intercellular carbon dioxide concentration,transpiration rate and rice yield were significantly affected by cultivation methods,but chlorophyll content was not significantly affected.The Comprehensive Evaluation System of rice yield index was established by principal component analysis,and the final order was Z1F1>Z2F 1>Z1F2>Z2F2,which was consistent with the results of variance analysis.The comprehensive rank of rice yield and quality was Z1F1>Z2F1>Z1F2>Z2F2 by using CRITIC weight method.Comprehensive consideration,rice-crab symbiosis and bacterial residue organic fertilizer-compound fertilizer mixed application model is the best model.(2)Two factors(depth of water layer W and amount of topdressing F)and three levels(depth of water layer W1-15,W2-20,W3-25cm,amount of topdressing ear fertilizer F1-10,F215,F3-20 kg/667m2)were used to conduct a randomized block micro area experiment The impact of yield and quality.The experiment showed that the depth of the water layer had a significant impact on plant height,stem diameter,Pn,Gs,and Ci,but had no significant impact on SPAD and Tr,The amount of topdressing has a significant impact on plant height,stem diameter,Pn,Gs,Ci,and Tr.The rice yield first increases and then decreases with the increase of water depth W.The levels of W1,W2,and W3 increase by 4.11%,6.68%,and 2.95%compared to CK,respectively;The levels of F1,F2,and F3 increased by 1.91%,4.67%,and 7.16%compared to CK,respectively,as the amount of topdressing increased.The chalkiness degree and chalky grain rate of rice first decrease and then increase with the increase of water depth W,and decrease with the increase of panicle fertilizer application amount.The protein content,viscosity,Amylose content and taste value of rice first increased and then decreased with the increase of water depth W,and increased with the increase of the amount of ear fertilizer and topdressing.Overall,the coupling effect of water and fertilizer in the middle water layer(20 cm)and high spike fertilizer application rate(20 kg/667m2)is the best.(3)The effects of shading degree(z),water depth(h),amount of top dressing(F)and amount of air(Q)on growth,yield and quality of rice crab were studied by means of orthogonal experiment with four factors and three levels,the degree of shading was set at the levels of no-shading(z 1),crab-shading(z 2)and crab-shading(z 3).The depth of water layer was set at the levels of low water layer H 1(10 cm),middle water layer h 2(15 cm)and high water layer H 3(20 cm),the amount of topdressing fertilizer was divided into three levels:low fertilizer(f 1),middle fertilizer(f 2)and high fertilizer(F 3).The filling capacity is set at three levels:low filling capacity(Q1),medium filling capacity(q2)and Kawkat filling capacity(Q3),the effects of different factors on rice growth index,physiological index,yield and quality were studied.The order of four factors affecting yield was shading degree>depth of water layer>fertilizer amount>aeration time.The optimum combination of the three factors was Z2H3F1Q2,that is,the depth of water layer was 20cm,the crab was shacding from the sun,the amount of top dressing was 30 kg/667m2,and the amount of air was 7mg/l.the growth of rice was good and the yield was high,the yield was 529 kg/667m2.(4)Taking economic benefits as the main factor and comprehensively considering economic benefits,ecological benefits and social benefits,under the conditions of rice crab symbiosis and fertilizer matching model experiment,rice crab symbiosis and bacteria residue Manure compound fertilizer mixed application model are preferred.This model can achieve the highest benefit per unit area and is the most friendly to the ecological environment under the condition of limited land resources;In the rice crab symbiotic water fertilizer coupling experiment,W2F3 is the optimal water fertilizer combination,which can achieve the goal of water conservation and quality improvement while ensuring profits;In the rice crab symbiotic water fertilizer air thermal coupling experiment,T6 treatment was the optimal combination,with a water depth of 20 cm,crab shading,topdressing amount of 30 kg/hm2,and aeration amount of 7 mg/L. |
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