Medium pressure (similar to 10 torr) low frequency (3-5 kHz) glow discharge (LFGD) plasmas were applied to treat wheat (Triticum aestivum) seeds to investigate the effects on water absorption, seed germination rate, seedling growth and yield. The LFGD plasmas were produced with air and air/O-2. Optical emission spectroscopic diagnostic methods were revealed that the N-2(C-3 Pi(u) - B-3 Pi(g)), N-2(+)(B-2 Sigma(+)(u) - X-2 Sigma(+)(g)) and N-2(B-3 Pi(g) - A(3)Sigma(+)(u)) produced with air, and O species were produced along with nitrogen species with air/O-2 plasmas, respectively. The SEM images were revealed that the surface architectures and functionalities of the seeds were modified due to plasma treatments. Water absorption was found to increase with treatment time. 6 min treatment was provided 95-100% seed germination. The plants grown from treated seeds for 3 and 9 min duration by air/O-2 plasma were showed the highest growth activity and dry matter accumulation. Total chlorophyll contents of the leaves, longest spikes and number of spikes/spikelet were also increased. The wheat yield was increased similar to 20% over control by 6 min treatment with air/O-2 plasma. Overall results revealed that LFGD plasmas can significantly change seed surface architecture, water absorption, germination rate, seedling growth and yield of wheat.