Abstract
Effects of spray of pH 2, 3 and 4 sulfuric acid solutions (5, 0.5 and 0.05 mM/1 respectively) on growth, biomass increment, levels of indoleacetic acid (IAA) and abscisic acid (ABA), and ethylene production in seedlings of woody plants were investigated. The application of the pH 2 solution to the shoot system of plants with a hand spray for 2 months significantly decreased growth and biomass of Cryptomeria japonica, Chamaecyparis obtusa, Pinus densiflora, Betula platyphylla and Ulmus americana seedlings. The pH 2 solution also enhanced ethylene production in these species. In B. platyphylla and U. americana seedlings, defoliation was accelerated by application of all of the acid solutions. The IAA content in needles or leaves was noticeably reduced in C. japonica, C. obtusa, P. densiflora and B. platyphylla seedlings by acid application, however, the ABA content was not affected.
