Review on application of plant growth retardants in medicinal plants cultivation Metabolism of Reactive Oxygen Species Involved in Increasing Root Vigour of Cotton Seedlings by Soaking Seeds with Mepiquat Chloride GhCPS and GhKS Encoding Gibberellin Biosynthesis Enzymes Involve in Inhibition of Leaf Growth by Mepiquat Chloride in Cotton (Gossypium hirsutum L.) Effects of Mepiquat Chloride on lateral roots initiation of cotton seedling and its mechanism