Abstract:The test researched in rule of influence of water and fertilizer coupling on the growth of flue-cured tobacco and on the absorption of nitrogen, which provides theoretical basis for promoting the techniques of the fluecured tobacco integrated with water and fertilizer. The experiment included four treatments: conventional fertilization(rain-fed), conventional fertilization combined with supplementary irrigation, 50% water and fertilizer coupling,and 100% water and fertilizer coupling. The plot was randomly designed and repeated for 3 times. The results show that: Compared supplementary irrigation with rain-fed, supplementary irrigation can promote the development and nitrogen absorption of flue-cured tobacco at the rosette stage, and that respectively increased the above-ground dry matter accumulation and the above-ground nitrogen absorption of flue-cured tobacco by 33.61% and 49.61%. In fast growing stage of flue-cured tobacco, compared water-fertilizer coupling with supplementary irrigation, the middle leaf and the upper leaf were significantly lower than the supplementary irrigation. In topping stage of fluecured tobacco, compared water-fertilizer coupling with supplementary irrigation, 50% water and fertilizer coupling can significantly increase nitrogen uptake in the stem, the middle leaf and the upper leaf of flue-cured tobacco by 22.83%, 32.05% and 114.45%, respectively. 100% water and fertilizer coupling can significantly increase nitrogen uptake in the stem of flue-cured tobacco by 19.50%. Before the topping stage of flue-cured tobacco, the dry matter accumulation and nitrogen absorption in the above-ground part of flue-cured tobacco treated with 50% waterfertilizer coupling were significantly lower than that treated with supplementary irrigation. At the topping stage, the dry matter accumulation and nitrogen absorption were increased by 14.15% and 44.54% respectively compared with that treated with supplementary irrigation. Compared water-fertilizer coupling and supplementary irrigation and rain-fed, the proportion of superior tobacco treated with 50% water and fertilizer coupling was significantly higher than the rain-fed and supplementary irrigation treatment, and the proportion of superior tobacco treated with rainfed and supplementary irrigation was increased by 11.62% and 7.6% respectively. The comprehensive analysis indicated that the coupling of water and fertilizer was beneficial to the growth, nitrogen absorption and leaf quality of flue-cured tobacco.