Meta-Analysis of the Impact of Drought Stress on Yield and Yield Components and Percentage of Oil Seed Sunflower

Many studies have been conducted on the effects of drought stress in the country and other parts of the world on oil sunflower and have been published as authoritative articles. Conclusions from a series of studies conducted using meta-analytic science help us to identify the trend of the effects of factors affecting the quantity and quality of sunflower production. This research is separated from various agricultural studies published in prestigious Iranian and foreign scientific journals and articles that were judged to be used in meta-analysis and then coded from among 62 articles; A total of 28 articles were analyzed in the meta-analysis process. The stresses applied in the studied articles were measured in three categories of normal irrigation (control) - moderate Stress - severe Stress based on the percentage of reduction of traits. Then the measured traits, which included 1000-seed weight, number of seeds according to seed oil percentage, to grain yield, were extracted from the articles. The results of drought stress meta-regression revealed that only the height trait had a considerable effect in severe drought stress; however, in the regression analysis, it was discovered that as linear stress increased, some investigated features declined, while trait Seed oil increased. With rising drought stress, this pattern remained practically consistent. The effect size of moderate and severe grain yield was insignificant compared to the control, among the results, the maximum effect size was 15 related to grain yield (-3/77), study on seed number (-3/31), study on 1000-seed weight (-0/68) and study on oil content (-0/6), drought stress according to priority, first on grain yield, number of seeds. Overall, the findings revealed that severe drought stress could significantly impact seed output and other features