Phenotypic diversity analysis of the fruit of Amomum tsao-ko Crevost et Lemarie, an important medicinal plant in Yunnan, China

Abstract

Amomum tsao-ko (Zingiberaceae) is a commonly used spice and medicinal plant. Morphological variations exist in the fruits of A. tsao-ko. In this study, we compared the phenotypic traits of fruits collected from nine regions in Yunnan Province, China. Based on the mean square values of fruit weight, number of ridges, seed weight, pericarp thickness, and seed diameter, the fruits of A. tsao-ko in Yunnan were grouped into three categories, corresponding to different regions in Yunnan. A principal component analysis revealed that the number of ridges, number of seeds per fruit, and vertical fruit diameter are the most variable parameters. Considering the genetic improvement potential at the regional level, A. tsao-ko in the regions of Gongshan, Tengchong, Jinping, Lushui, and Pingbian is the most efficient for breeding new cultivars, as the plants growing in these regions have a heavier fruit weight, larger fruit diameter, larger transverse diameter, greater number of ridges, greater seed number per fruit, heavier seed weight, moderate pericarp thickness, and larger seed diameter. Based on the selected area, the nested square analysis showed that the fruit vertical diameter, fruit diameter, and the number of seeds per fruit in the region are greater than the regional mean square, and the differences reached an extremely significant level as well. Thus, these three traits can be selected as genetic materials in this region for breeding.