Effects Of Regulated Deficit Irrigation And Nitrogen Fertilizer On Yield And Water-nitrogen Use Efficiency Of Peanut

Efficient irrigation and nitrogen management technique have made great achievements which have decisive roles in solving agricultural water shortage,efficient utilization of fertilizer and food requirement issues.Drought is still the primary factor affecting peanut yield.Applying excessive nitrogen fertilizer under drought conditions will not only increase production,but also increase the risk of nitrogen leaching.In order to slow down the decreasing trend of peanut yield and the low nitrogen use efficiency cause by drought and excessively applied nitrogen.A split plot field experiments using the“Baisha 1016”peanut variety as the material were conducted.The main plot is nitrogen and the sudplot is the water deficit.To study the effects of different water deficits and nitrogen rates on peanut growth?plant height dynamics and leaf area index?,dry matter accumulation and nitrogen accumulation in different organs,yield,water use efficiency,nitrogen use efficiency,and soil nitrate residue The impact of the adjustment of deficit irrigation to promote the growth of peanuts,dry matter and nitrogen accumulation of peanuts,and optimize the mechanism of nitrogen distribution and production increase.To achieve the purpose of water saving and high efficiency,and to provide a theoretical basis and technical support for the realization of a water-saving and high-yield planting pattern for peanuts.Detailed and chaptered conclusions are follows:?1?Increasing N application rate and water deficit had a significant effect on peanut growth and dry matter accumulation,and the highest plant height was 9.67%and 13.22%.Moderate water deficit treatment(55%⁹0%?_f,R₅₅)contributed to the increase in leaf area index of peanuts.Peanuts also have different growth centers at different growth stages.The highest dry matter accumulation at maturity was N₄₀R₅₅ treatment(40 kg·ha^-1 for nitrogen application,55%?_f for water deficit)and N₆₀R₅₅ treatment(40 kg·ha^-1 for nitrogen application,and 65%?_f for water shortage.),up to 113.41 and 109.42 g·plant^-1.?2?Increased N application rate and water deficit had a significant effect on N accumulation and N use efficiency in peanut at different growth stages.The application of nitrogen fertilizer increased the upper limit of nitrogen accumulation in plants.Rewatering after proper water deficit could optimize plant nitrogen distribution,increase nitrogen accumulation of pods,and increase nitrogen harvest index by 7.19%.The main effects of nitrogen application rate and water deficit for two years on the agronomic efficiency of nitrogen fertilizers,and the regularity of nitrogen fertilizer and apparent nitrogen recovery rate of peanut kernels were the same,but in 2017,both PNE and NRE exceeded 100%.There may be a risk of excessive depletion of soil nitrogen.Peanut WUE reached a maximum of 60 kg·ha^-1 for nitrogen application under rain-fed conditions,and they were 2.00 and 1.96 kg·m^-3,respectively.?3?Increasing nitrogen application and water deficit had a significant effect on peanut yield and yield composition.In the two years,the highest yield was achieved with N₆₀R₅₅,which was 6485.03 and 71327.30 kg·ha^-1 respectively.The output of 2017 was more affected by RDI.The increase of nitrogen fertilizer,water deficit and its interaction effect in two years had a significant effect on the yield of peanuts,and the highest percentage of kernels were treated with N₀R₄₅ in two years,which were 71.92%and 72.92%respectively.The highest fruit weight was obtained for N₄₀R₅₅,which was 158.20 g and 166.54 g,respectively.The highest kernel weights of peanuts treated with N₄₀R₅₅ and N₄₀R₀ were 65.90 g and 66.05 g,respectively.?4?Increasing N application rate and water deficit had a significant effect on the distribution and accumulation of nitrate nitrogen in soil.The law of nitrate content in different soil layers for two years was consistent,and showed that when the amount of irrigation was small,the content of nitrate nitrogen in surface soil was high,and when the irrigation volume was high,the content of nitrate nitrogen in deep layers was high.Nitrogen application increased the amount of soil nitrate accumulation,which increased linearly with the increase of nitrogen application rate.Regulated deficit irrigation caused the nitrate accumulation area to move downward,and the magnitude of the downward shift was significantly affected by heavy rainfall.?5?The traditional application of nitrogen at 60 kg·ha^-1 is relatively high,which is not conducive to the sustainable development of peanuts.Based on the analysis of the green high-efficiency model,applying nitrogen 47.80 kg·ha^-1 and the irrigation quota was 89.47 mm,scilicet R₅₅ and 47.80 kg·ha^-1 nitrogen was the best peanut water-nitrogen regulation modes,which had significantly save water.The mode can ensure the production capacity and achieve the goal of water-saving and efficient.Nitrogen application rate of 13.72 kg·ha^-11 and irrigation quota of 25.43 mm are conducive to the sustainable development of local peanut cultivation.Although the production is relatively low,it suffices the requirements of high production and water saving,and at the same time avoids the risk of the downward movement of the nitrate nitrogen distribution area and meets the green and efficient production of peanuts.In conclusion,Nitrogen application could promote the growth of peanuts,accumulation of dry matter and nitrogen,and adjust the deficit irrigation to optimize nutrient distribution and affect the distribution of nitrate nitrogen.The interaction effect of water and nitrogen is beneficial to the water saving and high yield of peanuts.Under the conditions of this experiment,it is recommended that the lower limit of irrigation in flowering-podding stage be 55%of the field water holding capacity.Through multi-objective analysis,it is known that the traditional application of nitrogen at 60 kg·ha^-1 is relatively high,which is not conducive to the sustainable development of peanuts,and the application of nitrogen at 47.80 kg·ha^-1 and the irrigation quota of 89.47 mm can satisfy water-saving peanuts,high yield,and high efficiency.