Fig. 1. A simulated wheat cultivation condition for rain-fed region of Afghanistan. (Visual photograph) The soil-filled 2 m PVC pipes were placed into big pools having 35 cm water level to maintain soil moisture until 1 m. (Image pipes) Soil moisture gradient along the 2 m PVC pipes showing dried zone at the middle (about 80 cm). Hypothetical long root was drawn to pass the dried zone whereas short root was drawn as restricted by dry zone.