Phenotypic diversity analysis of leaf traits in cultivated Houttuynia cordata Thunb. populations from Hunan Province

We studied the phenotypic diversity of leaf traits in cultivated Houttuynia cordata Thunb. populations from Hunan Province, China. Nine phenotypic traits and six relative traits of leaves were determined. Variance analysis, coefficient of variation, correlation analysis, principal component analysis (PCA), and cluster analysis were used to study the variation of leaf morphology. Results showed that:(1) There were significant differences in leaf phenotypic characters of the 20 H.cordata populations, and the differences among populations were greater than those within populations; (2) The average coefficients of variation for the 20 populations ranged from 5.63% to 9.08%, indicating low diversity among populations. The Youxian population (P16) had the highest coefficient of variation (9.08%), whereas the Xupu population (P3) had the lowest coefficient of variation (5.63%); (3) The average coefficients of variation for the 15 traits ranged from 3.71% to 10.28%, indicating that leaf trait diversity was low. The coefficient of variation for leaf area was the largest (10.28%) among the leaf characters, whereas the leaf width to leaf middle width ratio (W₂/W₄) was the smallest (3.71%); (4) Correlation analysis showed that leaf area had a significant positive correlation with leaf width, leaf middle width, leaf length, distance from leaf base to leaf width, and petiole length, a significant negative correlation with leaf tip angle, and no particular relationship with leaf base angle; (5) The cumulative contribution rate of the first three principal components for the 15 characters was 83.66%. By cluster analysis, the 20 populations could be clustered into four groups:heart-shaped, small heart-shaped, narrow heart-shaped, and large heart-shaped. These cluster results showed a discontinuous distribution pattern; (6) The common garden experiment showed that the diversity of leaf phenotypic traits was mainly determined by genetic material, and the diversity analyses could provide a theoretical basis for the breeding of excellent germplasm resources.