The Effect of Gibberellic Acid on Cell Width and the Cell-wall of Some Phloem Fibres

Treatment of plants of Cochorusoiltorius L., Hibiscus cannabinusL., and Cannabis sativa L. with gibberellic acid induced highlysignificant increases in cell diameter and wall thickness ofproblem fibres. This difference varies along the shoot and ismaximal in the middle region, internodes 10–15. The ratio is higher in treated plants. Gibberellic acid reduces the angle of orientation of the pits to the cellwall and also the pit frequency. Pits in treated plants arelonger and narrower in surface view.