Abstract: It is a common phenomenon that an infertile tiller dies away but its nodal roots survive during wheat growth and development. It is important to study the occurrence, growth, and function of nodal roots belonging to infertile tillers for both wheat ecophysiological theory and high-yield & highefficiency cultivation practice. We explored the occurrence, growth, and vigor of nodal roots belonging to infertile tillers and their relationships with grain yield, quality, and nitrogen use efficiency of the whole plant under different nitrogen application rates. The results showed that nodal roots belonging to infertile tillers occurred from growth recovering to jointing stage, and ended to develop during grain-filling stage, with the number of 7-15 roots per plant. From anthesis to grain-filling and mature stages, nodal roots belonging to infertile tillers increased first and then decreased, with a change ranging from 1 to 3 per plant. Physiological vigor of nodal roots belonging to infertile tillers was weaker than that belonging to fertile tillers, and the former gradually decreased with growth. The number of nodal roots belonging to infertile tillers was positively correlated with ears per unit area, and negatively correlated with grains per ear and grain yield. There was a positive correlation between physiological vigor of nodal roots belonging to infertile tillers and wheat yield and its components. As for grain quality, both the number and vigor of nodal roots belonging to infertile tillers were positively correlated with the contents of protein and soluble sugars of grains. The number and vigor of nodal roots belonging to infertile tillers in late growing period were positively correlated with partial factor productivity of applied nitrogen and nitrogen uptake efficiency. In conclusion, appropriate regulation and control of nodal roots belonging to infertile tillers in practice would be important for grain yield and quality formation of winter wheat.

Key words: winter wheat (Triticum aestivum L.), infertile tiller, nodal root, occurrence, function.