Nutrient restrictive factors and accumulation of super-high-yield summer maize.

A field experiment was conducted to study soil nutrient restrictive factors and plant nutrient uptake and accumulation of super-high-yield summer maize in 2007 and 2008.The results show that the maize yields are highest under the OPT treatment(By ASI),12051.2 kg/ha and 13246.3 kg/ha in 2007 and 2008 respectively.The nitrogen and potassium fertilization could evidently increase the yields by 8.92% and 7.14%,which indicates N and K are main nutrient restrictive factors.The accumulations of nitrogen,phosphorus and potassium of super-highyield summer maize plants are increased with the extension of the bearing period,and the nutrient accumulation amounts are maximum at the maturity stage.The order of nutrient accumulations is K2ONP2O5,and the absorbed nutrient ratio with 100 kilogram maize of N,P2O5 and K2O are 2.40∶1∶2.73.The key period of nutrient absorption is from the jointing stage to silking stage,and the absorbed nutrient rates are the highest.After the silking stage,maize plant absorbs more nitrogen and phosphorus.Leaf is distribution center of nitrogen and phosphorus from the seeding stage to silking stage,and the transfer efficiency of nitrogen and phosphorus are higher in stems and leaves at the late stages,while the transfer proportion of potassium is small.Nutrients are absorbed continuously at the whole growth period of super-high-yield summer maize,it is essential to super-high-yield topdressing after the silking stage that ensure adequate nutrients at the grain filling stage.