Effect of drought stress on yield and some physiological traits in Canola varieties

This research was conducted to assess the effect of drought stress on grain yield and some physiological characteristics of 28 canola cultivars. Cultivars were evaluated at two moisture environments (normal and drought stress) according to randomized complete block design. Results of analysis of variance showed that there was significant difference among canola cultivars for all measured traits except for chlorophyll (a/b) ratio. Results showed that drought stress reduced variation for most of the studied traits. Under both moisture conditions coefficient of genetic variability for proline and chlorophyll content was at highest level. Estimate of heritability was higher than 50% for most traits indicating a greater impact of selection to improve these traits. The result indicated that drought stress significantly increased proline content while decreased grain yield، yield components and other traits. Cultivar ‘NK fair’ had the highest grain yield in both stress and non-stress conditions. Under water stress condition Esc 6152 cultivar and under non-stress condition Gkh 305 cultivar had the highest relative water content (RWC) and in terms of this physiological trait were recognized as drought tolerant cultivar.