Study of Drought and Salinity Stress Effect on Some Physiological Characters of Two Canola (Brassica Napus L.) Varieties in Ahvaz

The aim of this study was to investigate the sole and combined effects of drought and salinity stresses on some physiological characters of two canola varieties in Ahvaz as outdoor pot experiment. This factorial experiment was based on randomized complete block design. Results showed that both salinity and drought stresses decreased seed yield, shoot dry weight, root dry weight, harvest index, biological yield, plant height, number of branches per plant and relative water content of leaf (RWC). Drought and salinity stresses increased SPAD value and relative membrance permeability (RMP). However, combined stress had a greater effect on these parameters than each sole stress. In the salinity stress, a significant positive correlation was observed between relative membrance permeability and shoot dry weight (r= -0.93**). Also, a significant negative correlation was found between relative membrance permeability and relative water content in combined stress (r= -0.94**). Relative water content was reduced because of damage to the membranes and increase of electrolytes leakage. Generally, Hyola401 variety exhibited better defensive mechanisms and more efficiency than Shirale in maintaing relative water content and relative membrance permeability in salinity, drought and combined stresses. The study showed that Hyola401 was more tolerant than Shirale under salinity, drought and combined stresses.