Physiological and Biochemical Evaluation of Commercial Oilseed Rape (Brassica Napus L.) Cultivars Under Drought Stress

Crop production worldwide is affected by the water deficit. Drought is a long irregular dry period, which happens in an area when it consistently receives below-average precipitation. In this study, impact of drought stress (irrigation after 80 (normal or control irrigation) and 160 (stress condition) mm evaporation from class A pan) on the growth and productivity of four oilseed rape (Brassica napus L.) cultivars (Oise, Triangle, Karun, and SLM046) was evaluated during 2011 growing seasons at the research farm of Yazd Agricultural and Natural Resources Research Center of Iran. Drought stress reduced seed and oil yield in all cultivars. The lowest and highest seed yield under drought stress was observed in Oise and SLM046 cultivars, respectively. The SLM046 cultivar had the lowest reduction of seed (27%) and oil (33%) yields under drought stress, compared to the control condition. On the other hand, the highest reductions of seed (57%) and oil yields (60%) under drought stress were observed in the Triangle cultivar (compared to the control condition). The SLM046 had the highest SPAD value, stomatal conductance (especially in early days of drought stress), proline, and leaf water content under drought stress, compared to other cultivars. Moreover, antioxidative activities (catalase and peroxidase activities) under drought stress were much higher in the SLM046 cultivar, which helped this cultivar to conquer oxidative stress under drought conditions. Overall, results indicated that the SLM046 cultivar is a drought-tolerant cultivar with excellent physiological performances.