Sugar beet is one of the important sugar crops in China, having high biological yield and high water consumption. The reasonable irrigation is one of the effective measures to save water and improve yield. In this experiment, the relationship among sugar beet yield, leaf area index, net photosynthetic rate, transpiration rate, leaf water potential, soil moisture and water consump-tion, and different irrigation water effects on sugar beet yield and water use efficiency were studied under plastic mulching with drip irrigation for two consecutive years in Inner Mongolia semi-arid regions. In high yielding sugar beet leaf area index was more than 7.37 in fast growth stage of leaf, 6.08-6.51, and 4.19-5.57 in root growth and sugar accumulation periods, in fast growth stage of leaf, root growth and sugar accumulation periods leaf water potential was 0.09-0.22, 0.18-0.39, and 0.26-0.48 MPa, net photosynthetic rate was 21.28-28.23, 21.90-28.75, and 22.06-26.58 μmol m-2s-1, respectively, transpiration rate in fast growth stage of leaf and root growth period was 9.36-10.21 mmol m-2s-1and 6.37-7.73 mmol m-2s-1, respectively, and more than 4.69 mmol m-2s-1in sugar accumulation period, water consumption was 140.15-312.78, 44.93-200.45, and 44.93-113.06 mm in the three growth stages, respectively. For high yield, high sugar yield and high water use efficiency, the reasonable irrigation water should be 1350 m3hm-2in the year of abundant rain (growth periods rainfall > 500 mm)and 1800 m3hm-2in the year of little rain (growth periods rainfall < 300 mm), which provides a theoretical basis and physiological indicators for sugar beet water-saving irrigation.%甜菜是我国重要的糖料作物, 其生物产量高, 需水量大, 合理灌溉是节约用水、提高产量的有效措施之一.本试验连续两年研究了内蒙古半干旱地区膜下滴灌条件下, 不同灌水量甜菜块根产量与叶面积指数、净光合速率、蒸腾速率、叶水势、土壤含水量和耗水量之间的关系, 以及不同灌水量对甜菜产量和水分利用效率的影响.结果表明, 高产甜菜的叶面积指数在叶丛快速生长期大于7.37, 在块根糖分增长期和糖分积累期分别为6.08~6.51和4.19~5.57, 在叶丛快速生长期、块根糖分增长期和糖分积累期叶水势分别为-0.09~ -0.22、-0.18~ -0.39和-0.26~ -0.48 MPa, 净光合速率分别为21.28~28.23、21.90~28.75和22.06~26.58 μmol m-2s-1, 蒸腾速率在叶丛快速生长期和块根糖分增长期分别为9.36~10.21 mmol m-2s-1和6.37~7.73 mmol m-2s-1, 在糖分积累期大于4.69 mmol m-2s-1, 耗水量分别为140.15~312.78、44.93~200.45和56.32~113.06 mm.甜菜产量、产糖量、水分利用效率均高的合理灌溉量, 在丰雨年份(生育期降雨量>500 mm)为1350 m3hm-2, 在少雨年份(生育期降雨量<300 mm)为1800 m3hm-2, 为甜菜节水灌溉提供了理论依据和生理指标.
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