Effects Of NH₄⁺-NO₃^- Ratio And Water In Seedling Stage On The Growth And The Yield Of The Potato In Dryland

The potato was tested in the field experiment.The splited aera was designed in this experiment.The main treatment was NH₄⁺—NO₃^- ratio and water supplement in seedling stage was the subsidiary treatment.The purpose of the experiment was to study the effect of water supplement in seedling stage and NH₄⁺—NO₃^- ratio of different state on growth,yield,water using efficiency(WUE) and N using efficiency of potato.Better configuration of the coupling of water and fertilizer were got initially.The results were as follows:1.The condition of water and fertilizer in the soil were improved dramatically when applying N fertilizer of different NH₄⁺—NO₃^-ratio and supplying water in seedling stage.So the plant was stronger and had thicker leaf,effectively increasing the photosynthetic rate and then increasing the yield and the quality of the potato.In semi-arid regions in Gansu,water supplement(supplementary water amount was 180m³/hm²) in seedling stage can increase the yield of the potato.2.The plant height was enhanced though water supplement in seedling stage and applying N fertilizer,increased by 1.43%and 26.09%separately,compared with the condition of no water and no N fertilizer.The photosynthetic rate of the potato was enhanced too.In A1B3 treatment,the photosynthetic rate even reached 20.33μmol·m^-2·s^-1.It was more effective for potato to apply N fertilizer in the early growth stage and NO₃^-—N was better than NH₄⁺—N for the effect of the photosynthetic rate.3.Under the condition of water supplement in seedling stage and NH₄⁺—NO₃^-ratio was 3/9,the three kind of WUE were the highest:output level was 65.16kg/mm.hm², leaf level was7.53μmolCO₂/mmolH₂O and group level was 101.81 kg/mm·hm².It showed that WUE had great effect on the yield of the potato and best WUE was good for the growth of the potato.4.Through the measurement of the two state of soil nitrogen,the results suggested that in spite of the potato crop prefered to NH₄⁺—N,NO₃^-—N was absorbed mainly under the condition of both NO₃^-—N and NH₄⁺—N in the drylands.The effect of mixing facilities were better than the single application.5.Under the condition of less soil water and rainfall in seedling stage,water supplement can improve soil moisture,increase N biological availability,which would benefit the absorption of N and improve efficiency of N.The highest efficiency of N was 28.45 kg/kg.The effect of different NH₄⁺—NO₃^-ratio was obviously.Water can influence the NHI obviously,but NH₄⁺—NO₃^- ratio hardly did.6.The best combination of water and nitrogen was A1B3(water supplement in seedling stage,NH₄⁺—NO₃^-ratio was 3/9).The yield of the potato reached 26280.82kg/hm².