Leaf-level phenotypic plasticity of Indigofera bungeana Walp.

We selected Indigofera bungeana Walp., the most widely distributed and morphologically varied species of Indigofera in China, to conduct analysis of variance, phenotypic plasticity analysis, and correlation analysis based on six leaf characters across 29 populations and 570 individuals using GIS technology. Results showed significant differences in the leaf characters of I. bungeana among populations, with greater differences found among populations than within populations. All studied I. bungeana leaf characters (i.e., leaf length, petiole length, minimal number of leaflets, maximal number of leaflets, leaflet length, and leaflet width) were plastic, with plasticity of leaf length and leaflet number found to be the largest and smallest, respectively. Leaf number can be used as a valuable taxonomic character. Average annual precipitation had the largest impact on leaf plasticity. In addition, all characters were negatively correlated with altitude, but positively correlated with average annual temperature. These results provide basic data for further studies on the taxonomy, adaptive evolution, and resource utilization of I. bungeana.