Influence of ventilation closures on plant growth parameters, acclimation and anatomy of leaf surface in Scrophularia yoshimurae Yamazaki - a medicinal plant native to Taiwan

Abstract

Different ventilation closures, including aluminum foil (AF) and a varying number of dispense papers (DP) had different effects on leaf growth parameters, in vitro rooting, survival rate and the anatomical features of the leaf surface of in vitro and ex vitro acclimated plants of Scrophularia yoshimurae—an important medicinal plant. The lowest plant growth parameters and ex vitro acclimation rate (<7.0%) were obtained using AF as ventilation closure. A scanning electron microscopy (SEM) study of leaf surfaces of plants derived from different ventilation closure treatments showed that parameters—including density and size of epidermal cell and stomata, size of guard cells, and stomata aperture-differed significantly among various treatments, and this in turn affected plant survival rate. Leaves derived from AF treatment had higher epidermal cell (15094 cells/mm2) and stomata (38/mm2) densities than DP treatments. Well-ventilated container closures, such as with DP, improved the morphological characteristics of leaves and in turn enhanced the survival rate during ex vitro acclimation (maximum rate being 66.7%). The present study not only provides an improved micropropagation method of S. yoshimurae but also gives scientific reasons for the different acclimation rates obtained with various container closures