離層酸對浮萍生長之影響

Dual Effects of Abscisic Acid on the Growth of a Duckweed

The plant hormone abscisic acid (ABA) is believed to be a dormacy factor in some seeds and buds; it often inhibits growth of plant organs. We found that ABA had dual effects on a duckweed tested (Lemna gibba L.). In these experiments, Lemna gibba plants were cultured under aseptic conditions on liquid E medium (containing minerals and sucrose) to which graded concentrations of ABA were added, and incubated in a growth chamber which gave continuous illumination from a bank of fluorescent tubes. The temperature was set at 28°C. The growth was measured 9 days after inoculation. The result shows that ABA at 10^-6M and above severely suppressed growth and multiplication of fronds (the green leaf-like vegetative structures); at 10^-7M it permited formation of miniature fronds (or turions), with subsequent expansion of fronds halted, and there was little increase in fresh weight; at 10^- 8M, 10^-9M, and 10^-10M, ABA greatly enhanced growth: number of fronds, fresh weight, and dry weight all increased (Table 1).