Enhancing the grain yield potential of wheat is a key focus of wheat breeders. Grain yield is the product of various yield components. Wheat grain yield per unit area is the product of grain yield per spike (GYS) and the number of spikes per unit area. The latter depends on sowing density and is highly affected by environmental factors. The GYS is determined by grain number per spike (GpS) and thousand grain weight (TGW), which are variably correlated in different wheat collections/populations. A significant negative correlation between these two traits has been reported in bi-parental populations [1–3], but no significant correlation was observed between TGW and GpS in collections of Chinese landraces , French winter wheat cultivars  and CIMMYT-derived spring wheat collections . On the other hand, a significant positive correlation between TGW and GpS was reported in modern Chinese cultivars .