Interaction Of Water And Nitrogen On The Yield And Sugar Content Of Sugar Beet Under Plastic Mulching With Drip Irrigation(PMDI)

【Objective】Interaction of water（W） and nitrogen（N）on growing process, dry matter accumulationand distribution, LAI, root yield, sugar content, and source libraries coordination regulation of sugar beetunder plastic mulching with drip irrigation（PMDI）were researched for revealing the high-yieldingmechanism, proposing a mode of water and fertilizer management of sugar beet in arid regions, which willprovide a theoretical basis for the precise formulation of irrigation fertilization system and the substantialincrease in root yield, sugar yield of sugar beet.【Methods】In this study, flood irrigation without mulching was chosen as the control in experiment a, theexperiment b of4water levels（W₁3000m3/hm², W₂5610m3/hm², W₃7200m3/hm², W₄9000m3/hm²）and4nitrogen levels（N₂10kg/hm, N₂130kg/hm²,N₃210kg/hm²,N₄300kg/hm²）under quadraticsaturation D-optimal design was arranged in6split plots at experimental station of Shihezi University in2012on sugar beet（Xintian12th）. Growth period, dry matter accumulation and distribution, tuber layerssugary rate, LAI and root/shoot ratio of Xintian12thwere determined during the20thto the160thd afteremergence. Sugar content of5roots from each treatment and root yield were measured at the same time.【Results】Germination rate, root yield, sugar yield and irrigation water use efficiency（IWUE）of PMDIcompared with CK were significantly increased by18.1%,30.67%,27.77%,30.67%respectively; sugarcontent was2.20%lower than CK, but the difference was not significant. Root yield of sugar beet withPMDI under interaction of water and nitrogen performed that, W₄N₃got the highest yield of94583kg/hm²,respectively241.6%,29.7%,170.2%,36.3%,10.2%higher than W₁N₁, W₄N₁, W₁N₄, W₂N₂and W₃N₄.Sugar content of sugar beet with PMDI under interaction of water and nitrogen performed that, W₁N₁gotthe highest sugar content of24.2%, respectively50.1%、19.0%、29.8%、38.7%、25.6%higher than W₄N₁,W₁N₄, W₂N₂, W₄N₃and W₃N₄. Sugar yield of sugar beet with PMDI under interaction of water andnitrogen performed that, root-body got the highest sugar yield, followed by root-crown, then root-top. Thehighest sugar yield of root-top, root-crown, root-body and tuberous root were respectively12.1、4.5、3.1、3.6times higher than the lowest. Difference of dry matter accumulation and distribution, LAI, sugarcontent, sugar yield and root/shoot ratio under different water and nitrogen were gradually expanded fromthe40thday after emergence to the end, and these indicators were stabilized during the130-160thdays afteremergence.【Conclusion】PMDI took better advantage of sugar beet yield and quality potential than CK. Water wasthe major factor of restricting root yield. N alleviated the adverse effects of drought on plants to someextent. Interaction of W and N promoted the yield, sugar yield and root/shoot ratio. Harvest should bebrought forward to early September（nearly the140thd after emergence）. Water and nitrogen（pure N）fertilizer should be used as3426-3600m3/hm²and139-177kg/hm²in the area.