Meta-Analytical Study of the Effect of Drought Stress on Cotton’s Performance and its Components in Iran

Researches related to the evaluation of the effect of the inputs dates back to long ago in Iran. However, due to the diversity and scattering of the various experimental results, it is difficult to reach to a general conclusion. The present study has made use of meta-analysis to overcome such a problem thereby to blend and reanalyze the findings of independent experiments for achieving a single result. To do so, the scientific-research articles published by the researchers from 1996 up to 2017 inside the country concerning the effect of drought stress on the performance, height and number of bolls in cotton were explored. The extend impact of an each trait is the mean difference of the drought stress results compared with control. The diagrammatic results of the drought stress and performance impact sizes showed that all of the stress levels make significant differences in contrast to the evidence treatment (p < 0.001). Moreover, it was made clear in a contrastive investigation of the diagrammatic results of the height and drought stress impact size and the number of the bolls and drought stress impact sizes that there is a significant difference between the evidence treatment and the total mean, the evidence treatment and 41%-55% of the cultivation capacity and the evidence treatment and 25%-40% of the cultivation capacity. The results of the cumulative diagram of the effect of drought stress on performance, height and number of bolls indicated that the majority of the studies fall on the left side of the diagram which is indicative of the adverse effect of the drought stress on the related traits. In addition, the results of the funnel chart demonstrated that the studies performed in Iran on cotton and drought stress are not much precise (bias and low sample volume).