Effects And Mechanisms Of Conventional Urea And Different Controlled Release Compound Fertilizers On Growth,Nitrogen Uptake And Utilization Of Winter Wheat

Nitrogen fertilizer can improve the yield and quality of wheat and plays an important role in wheat production.But excessive application of nitrogen fertilizer not only covers up the variety effect of wheat,but also causes problems such as low nitrogen utilization rate,low fertilizer utilization rate and environmental pollution in wheat production.Controlled release compound fertilizers can release nutrients into soil at rates that closely match the nutrient demands of wheat,which will reduce nutrient loss,improve wheat yield and nitrogen utilization rate,and solve the resource and environmental problems caused by excessive nitrogen application.However,there are a variety of controlled-release compound fertilizers in the market,and the effects are different.The optimum application rates of controlled release compound fertilizers are unknown.All of these lead to the serious abuse of controlled release compound fertilizers.In order to clarify the optimal high yield nitrogen application of conventional urea and the response of high-quality wheat varieties to the nitrogen application,as well as screen the best types and application rates of controlled release compound fertilizer,two field experiments were set up in this research.The experiment on the nitrogen application rate of conventional urea was carried out in2016～2017 and 2017～2018 at the Resources and Environment Experiment Station of Shandong Agricultural University.The conventional urea was used as the nitrogen fertilizer and the three nitrogen application levels were set at 0（N0）,120（N1）and 240 kg hm^-2（N2）.Three genotypes of high-quality wheat cultivars including Wengnong 5,Linmai 4 and Tainong 18 were used as experimental materials.A split-plot design was used in the field experiment.The nitrogen application levels were the main plots and the cultivars were the subplot.¹⁵N-microplot experiment was also included in each plot.The effects and mechanisms of conventional urea application rate on wheat growth,nitrogen uptake and utilization were studied to provide scientific basis for realization of great yield potential and appropriate fertilization management.In 2017～2018 year,the field experiment of compound fertilizers with different controlled release mechanisms of nitrogen was conducted using Jimai 22 at the experimental station of Weifang Academy of Agricultural Sciences.Four kinds of compound fertilizers with different controlled release mechanisms of nitrogen are selected in this experiment:loss-controlled controlled release compound fertilizer,peptide-chelated controlled release compound fertilizer,nitro double effect controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer.The effects and mechanisms of controlled release compound fertilizer（CRF）,10%reduction application of controlled release compound fertilizer（CRF10）,20%reduction application of controlled release compound fertilizer（CRF20）,and 30%reduction application of controlled release compound fertilizer（CRF30%）on wheat growth,nitrogen uptake and utilization were investigated to screen the types and application rates of controlled release compound fertilizers suitable for winter wheat production in East of Shandong,and the common compound fertilizer（CCF,the N,P,K contents of CCF were the same as CRF）was control for comparison.The main results are as follows:1.Effects of conventional urea application rate on the growth and nitrogen uptake and utilization of winter wheat:Increasing nitrogen fertilizer rate appropriately could increase the plant height of winter wheat,the photosynthetic pigment content in leaves,and dry matter accumulation in wheat growing period.The translocation amount of dry matter stored in vegetative organs before anthesis,the dry matter accumulation amount after anthesis and contribution to grain were significantly increased with the increasing nitrogen fertilizer application rate.Increasing nitrogen fertilizer rate appropriately also could improve panicle number and spike grain number to increase yield.Compared with N0 treatment,the N1treatment significantly increased the yield by 1.06～1.80 times,and the N2 treatment significantly the yield by 1.38～2.24 times.Application of nitrogen fertilizer could increase content of available nitrogen in soil to improve the soil nitrogen supplying in the wheat growing stage,reduce potassium loss of wheat plants in late stage of wheat growth,and significantly increase nitrogen,phosphorous and potassium accumulation in wheat plants.Compared with N0 treatment,the N1 treatment significantly increased the ¹⁵N uptake amount at depths of 20,60 and 100 cm by23.63%～36.72%,16.97%～30.02%and 1.27～1.85 times,respectively;the N2 treatment significantly increased the ¹⁵N uptake amount at depths of 20,60 and 100 cm by38.22%～54.45%,38.22%～54.45%and 1.11～1.68 times,respectively.The ¹⁵N uptake amount at depths 20,60 and 100 cm were significantly increased with the increasing nitrogen fertilizer application amount,but increasing the nitrogen application rate from N1 to N2decreased the ¹⁵N uptake amount at depths 100 cm.The nitrogen use efficiency（NUE）of W5,L4 and T18 were decreased significantly by 13.49%,15.01%and 16.37%,and the nitrogen partial factor productivity（NPFP）of W5,L4 and T18 were decreased significantly by 40.52%,41.57%and 42.92%with the increasing nitrogen fertilizer application rate.The mechanisms of response of different wheat varieties to nitrogen fertilizer:Under the same nitrogen application,the grain yield,NUE and the growth index of T18 were better than W5 and L4,but the agronomic efficiency of nitrogen（ANUE）of W5 was higher than T18 and L4.The extents of increasing of growth index,yield and the ¹⁵N uptake amount at different depths of W5 were relatively larger than T18 and L4 with the increasing of nitrogen level.The extents of decreasing of NUE and ANUE of W5 were relatively smaller than T18 and L4 with the increasing of nitrogen level.In conclusion,W5 was sensitive to nitrogen and T18 showed the characteristics of high-yielding and high-efficiency.The results show that 240 kg hm^-2 was the optimum nitrogen application rate and Tainong 18 was the better wheat cultivar in the middle region of Shandong.2.Effects of fertilizer application rates of compound fertilizers with different controlled release mechanisms of nitrogen on the growth,nitrogen uptake and utilization of winter wheat:Compared with CCF treatment,the CRF treatment of four kinds of controlled release compound fertilizers,the CRF10 treatment of loss-controlled controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer significantly increased the dry matter accumulation amount at maturity and the photosynthetic pigment content in flag leaves on grain filling.In addition,the CRF treatment of four kinds of controlled release compound fertilizers,the CRF10 treatment of loss-controlled controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer significantly increased the spike rate and panicle number to increase yield,with the grain yield increased by3.75%～13.11%.The CRF treatment of loss-controlled controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer were more beneficial to increase the yield,and the yield was increased by 13.11%and 6.85%.The CRF10 treatment of peptide-chelated controlled release compound fertilizer and nitro double effect controlled release compound fertilizer did not significantly affect the growth index and the grain yield,with the yield reduced by 0.1%～1.86%.The other treatments reduced the yield significantly.Compared with CCF treatment,the NUE and the nitrogen uptake efficiency（UPE）of the CRF treatment of four kinds of controlled release compound fertilizers were increased by3.58%～8.62%and2.67%～6.38%,and the NUE and UPE of the CRF10 treatment of four kinds of controlled release compound fertilizers were increased by 4.60%～10.30%and3.10%～8.80%.The loss-controlled controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer were more beneficial to increase the NUE and UPE.The extents of increasing of the NUE and UPE of CRF treatment were8.32%and7.30%,7.22%and 6.38%,and the extents of increasing of the NUE and UPE of CRF10 treatment were 10.30%and 9.99%,8.34%and 8.80%.The results of research show that the grain yield and efficiency of Jimai 22 could be increased by the application of full fertilizer and 10%reduction in amount of the loss-controlled controlled release compound fertilizer and urea-formaldehyde controlled release compound fertilizer in East of Shandong.