Effects of Different N,P and K Fertilizer Levels on Photosynthetic Physiology and Yield in Maize

The studies on parameters of photosynthetic physiology and yield were carried on maize hybrid Shen Dan 16 at different levels of N,P and K fertilizer.It is shown that there was a significantly positive relationship between the net photosynthetic rate(Pn)and transpiration rate(Tr) and stomatal conductance(Gs) of summer maize under N,P and K fertilizer.Especially,It is optimal under treatment of OPT.The rate of increase of net photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr) in treatment of OPT-P/2,OPT+P/2,OPT-K,OPT-N,OPT-P are decreased gradually comapared to CK.However,it is not obvious that phosphate fertilizer impact to net photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr).The highest grain yield of corn,12 777.0 kg/hm2 is obatined in best teatement of OPT fertilization,significant increased 31.6% comapred to CK. Interaction of NPK fertilizers based on treatment OPT were positive on the corn yield.And it is optimal under OPT treatment especially.