The experiments were carried out on the farm of Henan agricultural university

during 2003-2004

using high-gluten cultivar Yumai 34 as material. This study was to clarify photosynthetic characteristics and grain yield variations with different N

P

K and S rates

so as to provide some experimental foundations for reasonable N

P

K and S fertilization of wheat. The results of the study revealed that under the field fertility of this experiment

rates of N

P

K and S had obvious adjust effect on canopy photosynthetic rate

chlorophyll content and nitrate reductase activity

and all photosynthetic characteristics indices increased with N

P

K and S supply

but the most powerful fertilizer factor at different date after anthesis was different. Combined fertilization of N

P

K and S also obviously regulated grain yield

and effect of S and N on yield was at 0.01 significant level

while effect of P and K was not. NTOP120K180S30 treatment was the optimum combination.