Importance of harvest index in drought resistance of sorghum

In order to study the influence of harvest index on drought resistance in sorghum, forty-four varieties were planted under two levels of moisture stress, well-watered and water-stressed, with three randomized blocks for each level. Drought resistance was determined as the relative yield loss due to moisture stress. It was compared with the concurrent losses in harvest index. Severe moisture stress resulted in an average yield loss of 44%. On average, resistant and intermediately resistant varieties were also resistant to losses in harvest index. These results confirm that the maintenance of harvest index by means of channeling assimilates to the developing ear is an important drought resistant mechanism in sorghum.