Investigation of the Effect of Irrigation Interruption at Different Stages of Development on Yield and Yield Components of Rapeseed Using Meta-Analysis

The purpose of this study is to use meta-analysis to combine the results of experiments conducted in Iran on the effect of drought stress due to irrigation cessation at different stages of development, on yield and yield components of canola. The studied traits include grain yield, oil and dry matter, number of pods per plant, number of seeds per pod, 1000-seed weight, and grain oil content. Results show that all traits under the influence of stress at different stages of development are significantly affected by drought stress. Irrigation interruption in different stages on average cuts grain yield by 34.5%, oil yield by 36%, oil content by 4.7%, dry matter by 25.8%, number of pods by 35.4%, seeds per pod ratio by 18.5%, and 1000-seed weight by 17.5%, while raising the proline content by 49.9%. The highest reduction rate in grain and oil yield belongs to the irrigation cut-off treatment, in turn leading to a reduction of 41% and 46% of these two traits, respectively. Also, regarding the yield components, the highest reduction in the number of pods per plant, number of seeds per pod, and 1000-seed weight is observed in the cut-off treatments of stem, flowering, and podding, respectively.