Tolerance to Cadmium in Ramie (Boehmeria nivea) Genotypes and Its Evaluation Indicators

Abstract

Cadmium (Cd) is a heavy metal element toxic to plant, animals and humans. Planting ramie varieties in Cd contaminated soils can prevent Cd flow into food chains. In this study, the Cd tolerance of 9 ramie genotypes was compared in hydroponic culture and field microplot experiments, and the indicators to evaluate the tolerance were analyzed. In the hydroponic culture experiment, significant genotypic variations were found in plant height, leaf number per plant, shoot dry weight, and root dry weight in different Cd treatments; and shoot dry weight was significantly correlated with plant height, SPAD reading of leaf, and root dry weight. In the field experiment, shoot dry weight was significantly correlated with plant weight, stem diameter, and bark thickness. These phenotypic traits could be used as indicators for Cd tolerance evaluation. Clustering analysis based on the comprehensive tolerance of both experiments showed 3 groups of the 9 ramie genotypes, which were characterized with high, moderate, and low tolerance to Cd. For screening ramie genotypes with Cd tolerance, plant height, SPAD reading of leaf, shoot dry weight, and root dry weight can be used as selection indicators in hydroponic culture experiment.