Researchers studied different wheat genotypes to identify traits that contribute to higher grain yield. They looked at factors like leaf area, growth rates, tiller and spike numbers, and grain weight. The N-81-18 line had the highest grain yield, with more grains per spike and heavier spikes. They found a strong link between grain yield and harvest index in all genotypes. Spike weight had the biggest direct impact on grain yield, while leaf area had a negative effect. Despite this, the positive correlation between leaf area and grain yield was actually indirect.