Effects of some plant growth regulators on stem anatomy of radish seedlings grown under saline (NaCl) conditions

In this work, effects of gibberellic acid, 2-chloroethylphosphonic acid (ethephon), triacontanol, 24-epibrassinolide and polyamine (cadaverine, putrescine, spermidine, spermine) pretreatments on the stem anatomy of radish seedlings grown under saline conditions were studied. Salt stress decreased the stem diameter, epidermis cell size, cortex zone thickness, vascular bundle width, cambium thickness, xylem width, trachea diameter and phloem width in the seedlings non-pretreated with the growth regulators, in comparison with the control seedlings grown in distilled water medium. In addition, it slightly increased the cuticle thickness. On the other hand, many of the growth regulator pretreatments more or less stimulated the stem diameter, epidermis cell width, cortex zone thickness, vascular bundle width, xylem width, trachea diameter and phloem width in comparison with the control seedlings grown on saline medium. Moreover, they generally reduced the cuticle thickness, epidermis cell length and cambium thickness.