Effect of Different Irrigation Frequency and Amount on Nitrogen Uptake,Translocation of Winter Wheat

A field experiment involving six irrigation treatments(from none to five irrigation application),was to determine the effects of irrigation amount and frequency on the nitrate nitrogen(NO3——N)in soil layers(0-60 cm)and the translocation of accumulation nitrogen in wheat plants.The experimental results showed that the water condition had an impact on the amount and distribution of NO3——N in soil.NO3——N amount significantly decreased as irrigation frequency increased when partial NO3——N can be collected in soil depth of 20-40 cm.The irrigation none treatment had a highest nitrogen accumulation at the stage of sowing to rejuvenating,then remarkably lower than the other treatments at 0.05 probability level.Irrigation frequency from one to three had a higher nitrogen accumulation amount than four and five after anthesis.The post-anthesis nitrogen translocation rates from leaves and stems to spikes were 82% and 75% respectively.Rate of leaf nitrogen translocation rose with increasing irrigation frequency,but stem translocation rate reversely.Contribution of nitrogen from leaves,stems and post-anthesis assimilation nitrogen to spikes were 34%,32% and 34% after anthesis.The distribution rate of nitrogen accumulation in spikes had no significant difference between treatments at maturity.Irrigation two and three had a higher uptake and utilization efficiency of nitrogen from soil.From above we concluded sufficient irrigation amount led soil NO3——N to leak and low soil nitrate had no helpful for nitrogen assimilation in wheat plants.Moderate water deficit was favorable for nitrogen accumulation,nitrogen uptake efficiency and water utilization efficiency to increase.The translocation rate from leaves was larger than from stems,and 66% of spike nitrogen came from vegetative organs nitrogen mobilization,the other 34% was derived from post-anthesis assimilation nitrogen.So irrigation two or three was a reasonable irrigation method for balancing water-nitrogen utilization efficiency in north china plain.