Interaction Effects Of Nitrogen And Potassium On Yield,Nutrient Accumulation And Translocation Of Spring Sown Fresh Waxy Maize

The climatic characteristics of rain and heat synchronization,the cyclic alternation between dry and wet in the southern maize season,as well as the unbalanced supply of fertilizers with highly intensity and excessive nitrogen(N)and less potassium(K),lead to the decrease of soil fertility year by year.In recent years,the production of maize has been adversely affected by the imbalanced application of heavy N fertilizers and insufficient K fertilizers.This phenomenon has resulted in higher production costs,worsened environmental pollution and problems such as soil compaction,which are detrimental to the green and sustainable development of agriculture.In this study,fresh waxy maize varieties S YN5 and S YN11 were selected as the test varieties.Two N levels(N12 and N15,corresponding to N 180 and 225 kg/hm2)and four K treatments(K0,K5,K10 and K5+5,corresponding to K2O 0,75,150 and 75+75 kg/hm2)were set.A field experiment was conducted to investigate the effects of N and K fertilization on yield and nutrient utilization.The main findings are as follows:1.Under the same N level,the LAI and SPAD values of fresh waxy maize during the growth period increased with increasing K application rates.The fresh ear yield and fresh grain yield also increased with increasing K application rates.However,at the same K treatment,there was a small difference in fresh ear yield and fresh grain yield between N12 and N15.Improving the K fertilization method,K5+5 further increased the yield.2.The interaction of N and K is beneficial for the accumulation and transportation of dry matter in fresh waxy maize,and the differences in dry matter accumulation and transportation between N12 and N15 were small.Higher application rates of K can guarantee a higher amount of dry matter during the silking period and stable dry matter accumulation after silking.K application increased the dry matter translocation amount(TA)from the stems and leaves to the grains,thereby increasing yield of fresh waxy maize.3.The interaction of N and K promoted the accumulation and transportation of N,phosphorus(P),and K in fresh waxy maize,and the differences in N,P,and K accumulation and transportation between N12 and N15 were small.Under the same N level,the accumulation of N and K increased with increasing K fertilizer application,while the accumulation of P initially increased and then decreased.The interaction of N and K mainly promoted the transport of N and P in stems and the transport of N,P,and K in leaves,which facilitated nutrient transport to grain.Improving the K fertilization method,K5+5 further increased the TA,translocation rate(TR),and translocation contribution proportion(TCP)of N,and significantly increased the TA,TR,and TCP of P and K.4.Overall,with the increase in K fertilizer application rate,the N partial fertilizer productivity(PFP)and P PFP of fresh ear and fresh grain also increased,with the highest value observed in K5+5 treatment.However,the K PFP and K agronomic efficiency(AE)of fresh ear and fresh grain all significantly decreased with the increasing K fertilizer application rate,except in K5+5 treatment,where they were slightly improved but still lower than those in the K5 treatment.The apparent recovery efficiency(RE)of K also decreased significantly with the increasing K fertilizer application rate.The AE and RE of K were significantly increased under K5+5 treatment with the same amount of K application and an improved K fertilization method.At the same K treatment,overall,the N PFP was higher at N12 than that at N15,while the K PFP was lower at N12 than that at N15,and there was no significant difference in P PFP between the two N levels.In summary,reasonable N and K fertilization can improve the LAI and SPAD values of fresh waxy maize,which is conducive to improving photosynthetic production capacity and promoting the accumulation and translocation of dry matter and NPK nutrients,thus promoting yield improvement.The accumulation of K and the translocation of N have the greatest impact on fresh ear yield and fresh grain yield,and a higher accumulation of K and translocation of N during the fresh stage were beneficial for high yield of fresh waxy maize.Considering yield,fertilizer utilization efficiency,and economic benefits,it is recommended to apply K fertilizer in stages and appropriately reduce N fertilizer input to 180 kg/hm2,which can achieve a high yield and high efficiency in fresh waxy maize.