[Effects of long-term application of nitrogen fertilizer on leaf chlorophyll fluorescence of upland winter wheat].

The effects of long-term nitrogen fertilization of chlorophyll fluorescence of winter wheat at its grain-filling stage on Loess Plateau highland were studied. The results showed that the actual photochemical efficiency of PS II reaction center (phi PS II) was decreased with leaf water stress aggravated, while was increased by nitrogen supply. The phi PS II of 0 kg.