The relationship between root development and drought resistance of two Eucalyptus species (Eucalyptus microtheca Muell and Eucalyptus sargentii Maiden)

Drought stress is one of the most important factors reducing the plant growth and yield. Due to the complexity of factors affecting the drought tolerance or resistance in plants and access to relevant mechanisms, researchers are faced with challenges. Studying the root development can be considered as an important indicator in this regard. On the basis of this study how the development of two species of Eucalyptus roots under drought conditions and at different depths in lysimetric conditions were taken into account. Drought stress was applied in three irrigation levels, including: 100% field capacity (control), 70% field capacity (moderate stress) and 40% field capacity (sever stress) in three replicates. Effects of drought stress on root weight development were studied in six deeps, including: 0-20, 20-40, 40-60, 60-80, 80-100 and 100-120 cm. The results showed that increasing drought stress reduced the roots development in both species significantly. E. micortheca produced more roots than E. sargentii in varying levels of drought stress. The roots of E. microtheca had more deep penetration than E. sargentii in all drought stress treatments. Due to the reasons mentioned, E. microtheca is more resistant to drought stress than E. sargentii.