Morphological Variations among Indigenous Chinese Potato (Plectranthus rotundifolius L.) Accessions in Sri Lanka

Abstract

Plectranthus rotundifolius is an herbaceous tuber crop belonging to the family Lamiaceae. The purpose of this study was to evaluate the morphological diversity of indigenous P. rotundifolius accessions in Sri Lanka and to identify the crop's yield capacity and yield determinants. Sixteen indigenous accessions of P. rotundifolius were evaluated for fifteen qualitative and quantitative characteristics. The experiment was conducted using a randomized complete block design (RCBD) with three replicates, and each plot measured 1 m × 3 m. Quantitative data were analyzed using SPSS. There were significant differences among the studied accessions in each of the considered characteristics. Three principal components (PCs) were identified, each with an eigenvalue greater than 1. Principal component analysis explained 75.8% of the total variance, with PC1, PC2, and PC3 accounting for 42.7%, 22.0%, and 11.1%, respectively, highlighting the major traits contributing to morphological diversity among the accessions. PC1 was mainly associated with leaf length (90.6%), leaf width (89.7%), number of leaves per plant (88.4%), number of branches per plant (85.8%), internodal distance (85.2%), canopy height (78.3%), and yield per plant (75.8%). According to the hierarchical dendrogram, three clusters were identified at a cluster distance of 14. Cluster I encompassed accessions distinguished by their limited vegetative growth. Vegetative traits showed strong positive correlations among leaf width, leaf number, canopy height, and branching (r = 0.652–0.880), while stem diameter correlated positively with canopy height (r = 0.813). The yield per plant demonstrated a positive correlation solely with the number of tubers per plant (r=0.705), with no other agronomic traits exhibiting significant associations with the yield. Further, the number of tubers per plant was negatively correlated with stem diameter (r =- .464). PC analysis demonstrated considerable diversity among the accessions by identifying the major traits contributing to total variation and distinguishing morphologically diverse genotypes suitable for breeding and conservation purposes.