The researchers studied 57 types of bread wheat to find out which traits affect grain yield. They planted the wheat in a specific way and analyzed the data. They found that traits like number of tillers, spike length, and weight of grains per spike are important for high grain yield. These traits are directly linked to how much wheat each plant produces. Harvest index and biological yield also play a big role in determining grain yield. By focusing on these traits, breeders can improve wheat plants to produce more grains.