This book helps to know how the AM fungi regulate drought stress. Drought is an abiotic stress that has a drastic effect on the growth and development of plants, especially at the seedling stage. Drought at the seedling stage has been identified as the trigger for widespread plant mortality events around the world. Being hardy, the Custard apple grows well under rainfed farming. However, its growth and development are severely affected at times under drought situations due to the receipt of erratic rainfall and the prevalence of high temperatures.