Effects of Different Aluminum Levels on Growth and Root Anatomy of Alnus hirsuta Rupr. Seedlings

Abstract

This study was conducted to compare the growth and mineral nutrient composition of Alnus hirsuta seedlings when treated with different aluminum concentrations and acidic nutrient solutions with and without Frankia inoculation and to examine microscopic changes in the roots treated with different aluminum levels with and without Frankia inoculation. When inoculated with Frankin, A. hirsura seedlings without A1 treatment showed the greatest growth rate in height; root length and fresh weight. The seedlings treated with Al grew better in height, root length and fresh weight in the presence of Frankia than those uninoculated with Frankia. As the concentration of Al treatments increased, the concentration of Al in both shoot and root increased regardless of Frankia inoculation. As the concentration of treated Al increased, the concentration of cations (Ca, Mg, K) in the tissue decreased. The root tissues treated with A1 showed the following microscopic characteristics as compared to those without Al treatment; presence of electron dense bodies in vacuoles, and between plasmalemma and cell wall, accumulation of phenolic materials in vacuoles, disrupted tonoplast, and increase in vacuolation. These alterations in root anatomy were observed at 50 mg/L Al treatment. The degree of alteration was more severe in the root tissues uninoculated with Frankia than those inoculated with Frankza.