When does drought stress cause the greatest yield reduction in grain sorghum?

Drought stress has the most significant impact on grain sorghum during the boot stage, which is the period just before the flowering process begins. This is a critical time for the plant, as it is when the seed heads are developing and forming, requiring substantial water for optimal growth. If drought conditions occur during this stage, the plant may fail to develop fully, leading to reduced grain yield and quality.

Water stress during earlier stages, such as seedling emergence or vegetative growth, can affect establishment and overall plant vigor, but the boot stage is particularly crucial for the success of grain formation. During this time, the plant's physiological processes are shifting to support reproductive development, and any water deficit can critically compromise yield potential.

Thus, understanding the importance of water availability at this stage allows agronomists and farmers to implement irrigation strategies effectively to mitigate yield loss during drought conditions.