Study On The Effects Of Rice-Crayfish Co-Culture Mode On Absorption Of Medium And Trace Elements In Rice And Rice Quality

Rice-shrimp integrated cultivation is a kind of ecological cultivation mode that introduces crayfish into paddy fields,increased the biodiversity of paddy fields,improves the ecological environment of paddy fields,and co-exists with rice.In recent years,it has been widely popularized,However,under the rice-shrimp integrated cultivation model,the influence of rice on the relationship between absorption of medium and trace elements and rice quality and its mechanism remain unclear.In this study,field experiments of different lobster species and densities were conducted.Four treatments were designed: rice monoculture(R),rice cocropping with Procambarus Clarkii in low density(RCL),riceco-cropping with Procambarus Clarkii in high density(RCH)and rice co-cropping with Cherax quadricarinatus(RA).To explore the effects of different rice and shrimp integrated cultivation modes on the availability of trace elements in soil,the absorption of trace elements in rice,the yield and quality of rice,and to clarify the relationship between rice quality and trace elements in rice under different co-cropping modes.The main research results are as follows:(1)Rice-shrimp co-cropping mode decreased soil p H value compared with rice monoculture mode;Compared with rice mono-cropping,rice-shrimp co-cropping significantly increased soil organic matter content.Compared with rice mono-cropping,riceshrimp co-cropping significantly increased available potassium,nitrate nitrogen and ammonium nitrogen contents,and significantly increased soil available nutrients,and RCH treatment had the best effect.(2)Compared with rice mono-cropping mode,rice-shrimp co-cropping mode increased the available contents of medium and trace elements in soil,among which,the available contents of Fe,Ca and Mg increased significantly,while the available copper contents in soil were not significantly different among different treatments.Compared with rice monocropping mode,rice-shrimp co-cropping mode could promote the absorption of medium and trace elements in rice,and the contents of Fe,Ca and Mg were significantly increased,which was related to the significant increase of available medium and trace elements in soil.Compared with R treatment,iron content of RCH,RCL and RA treatment increased by52.02%,23.39% and 21.37%,respectively.Calcium content increased by 45.73%,32.13%and 22.81%,respectively.Magnesium content increased by 44.97%,28.61% and 23.35%,respectively.RCH treatment was superior to RCL and RA treatment in increasing the content of medium and trace elements in soil and rice.(3)Rice quality could be significantly improved by the co-treatment of rice and shrimp,which was related to the increase of the contents of medium and trace elements in rice.The correlation analysis between mineral element content and rice quality showed that the protein in rice quality was significantly positively correlated with Fe,Ca and Mg,and the gum consistency was significantly positively correlated with Fe,Ca and Mg.There was a significant negative correlation between amylose content and Fe and Mg,and a very significant negative correlation between chalk grain percentage and Fe,Ca and Mg.The appearance,cooking and nutritional quality of rice can be effectively improved by increasing the content of medium and trace elements in rice under rice-shrimp co-cropping.(4)In terms of economic benefits,rice yield under rice-shrimp co-cropping(RCH,RCL and RA)was not significantly different from that under rice mono-cropping(R),and riceshrimp co-cropping could achieve stable rice yield.In rice-shrimp co-cropping mode,the rice quality improved,the market price was higher than that of rice monocropping,and the market price of crayfish was higher,and the shrimp yield increased.Compared with R treatment,the net yield of RCH,RCL and RA treatment increased 506%,314% and 429%,respectively,and finally increased the ecosystem yield.In conclusion,the rice-shrimp co-cropping mode can increase the available content of trace elements in soil,promote the absorption of trace elements in rice grains,and ultimately improve rice quality and increase economic income.Among them,aquaculture within a reasonable range can promote the ecological and economic benefits of rice-shrimp cocropping mode.