The researchers studied different wheat varieties to see how well they could handle drought conditions. They looked at factors like plant dry weight, spike numbers, photosynthetic rate, proline content, and chlorophyll content. They found that the drought resistance index and yield decrease index are good indicators of a wheat variety's ability to resist drought. Varieties with higher drought resistance had more spike numbers and higher plant dry weight. The photosynthetic rate, proline content, and chlorophyll content in the flag leaf can help identify which wheat varieties are better at handling drought.