[Effects of water-fertilizer spatial coupling in root zone on winter wheat growth and yield]

A soil column experiment was conducted to study the winter wheat growth and yield under effects of different soil wetting (overall wetting, upper part wetting, and lower part wetting) and fertilization (overall fertilization, upper part fertilization, and lower part fertilization). The plant height and leaf area at tillering stage decreased significantly under lower part fertilization, compared with those under upper part and overall soil fertilization, but had no significant differences under different soil wetting. At jointing stage, the plant height was higher when the soil wetting and fertilization were at same location than at different location, manifesting a synergistic coupling effect of water and fertilizer. Lower part soil wetting and lower part fertilization decreased the root-, shoot-, and total dry biomass significantly, upper part fertilization benefited the biomass accumulation of winter wheat, and upper part soil wetting combined with upper part fertilization had an obvious coupling effect on the shoot- and total dry biomass. Soil wetting and fertilization at same location induced a higher ratio of root to shoot, compared with soil wetting and fertilization at different location, and lower part soil wetting resulted in the maximum water use efficiency (WUE), compared with upper part and overall soil wetting. A higher WUE was observed in the soil wetting and fertilization at same location than at different location, but a lower WUE was induced by lower part fertilization. The grain number per spike under upper part and overall soil wetting was increased by 41.7% and 61.9%, respectively, compared with that under lower part soil wetting, and this yield component under upper part and overall soil fertilization was also higher, compared with that under lower part fertilization. Upper part soil wetting and fertilization had an obvious coupling effect of water-fertilizer on the yield and yield components (except for 1000-grain mass). Different soil wetting and fertilization affected the yield mainly through affecting the grain number per spike.