The researchers studied how different traits of maize plants affect grain yield. They looked at plant height, cob length, cob diameter, and 1000-grain weight in two experimental fields. They found that these traits were all positively related to grain yield and to each other. Plant height had the biggest direct impact on grain yield, followed by 1000-grain weight. Cob diameter was not as important as the other traits in predicting grain yield. Overall, plant height and 1000-grain weight were the most crucial factors for a high maize yield.