Varieties And Irrigation Model Of Rice Growth And Pollutant Emission Impact Study

With the development of society,water resources are becoming increasingly scarce,placing higher demands on agricultural production,which needs to balance both water conservation and high yields.Non-point source pollution caused by agricultural production has also become a difficult problem.In order to better address these issues,this study focuses on rice,one of the main staple crops,to explore new approaches for sustainable agricultural development.Field experiments were conducted by selecting rice varieties and irrigation methods as the two factors,and data collection and analysis were carried out on rice growth,water utilization,and pollutant emissions.The study examined the impacts of variety and irrigation method on growth indicators,water consumption,and pollutant loadings,and identified the optimal combinations of different varieties and irrigation methods.The main conclusions obtained are as follows:(1)The variety has a significant impact on various growth indicators.Under the same irrigation mode,the tiller number of Hybrid rice increased by 2.7±1.0 on average compared with conventional rice;The area of the upper three leaves increased by 6.8%～58.2%;Root length increased by 12.4%～86.6%;The total dry matter increased by 42% to 141%.Except for tillering,irrigation mode has a significant impact on the leaf area,root length,and dry matter quality of the upper three leaves,mainly affecting the trend of growth indicators changing with the growth period.The change trend of dry matter quality is less affected by irrigation mode,while the change trend of upper three leaf area and root length is more affected by irrigation mode.(2)The effects of varieties and irrigation modes on the yield reached a significant level.Under different irrigation modes,the yield of Hybrid rice increased by more than 31.2%compared with conventional rice;Compared with conventional irrigation,the yield changes under the other three water-saving irrigation modes range from-0.9% to 2.1%.Among the four irrigation modes,the thin dew irrigation mode has the largest yield.The yields of conventional rice and Hybrid rice are 574.1kg/mu and 753.4/mu,respectively,2.1% and 1.4%higher than that of conventional irrigation(p>0.05).(3)The variety,irrigation mode,and their interaction have a significant impact on irrigation volume,drainage volume,leakage volume,and water productivity.The various water quantity indicators are mainly influenced by irrigation modes,and water productivity is mainly influenced by varieties.Compared with conventional irrigation,the irrigation volume of thin dew irrigation,rain storage thin dew irrigation,and furrow and border suitable rain irrigation decreased by 39.4%,74.5%,and 91.4%,respectively;Water productivity increased by 50.1%,9.9%,and 19.9%.Compared with conventional rice,irrigation amount of Hybrid rice increased by 3.6%,and water productivity increased by 29.7%.(5)The concentration of various types of pollutants is influenced by various factors such as soil moisture conditions,permeability,self transformation characteristics of pollutants,and the absorption and utilization of them by rice.There is no clear and consistent pattern for various pollutants.The pollutant load is jointly determined by the concentration and water volume,but the difference of concentration is not enough to change the difference of water volume,so the pollutant load is mainly affected by the drainage volume and seepage volume.The total TN and TP load of Hybrid rice increased by 4.2% and 13.3% respectively compared with conventional rice.Compared to conventional irrigation,the total TN load decreased by20.6%,74.4%,and 83.0% for thinly exposed irrigation,rain-storage thinly exposed irrigation,and furrow suitable rainfall irrigation,respectively.The total TP load increased by 32.5%,decreased by 76.4%,and 84.5%,respectively.(6)According to the experimental data,TOPSIS method was used to calculate and optimize each treatment.The optimal treatment was the combination of Hybrid rice and furrow border irrigation mode.Under the same irrigation mode,Hybrid rice is superior to conventional rice;Under the same variety,the advantages and disadvantages of each irrigation mode are in order: suitable rain irrigation for furrow and border,rainwater storage and thin dew irrigation,thin dew irrigation,and conventional irrigation.