Principal Component Analysis for Morphological, Seed Reproductive, and Phenology Traits in 16 Sunn Hemp (Crotalaria juncea L.) Accessions

Sunn hemp, Crotalaria juncea L. is a tropical legume grown for fiber, cover cropping, and as a green manure crop with potential to contribute to sustainability. Sixteen sunn hemp accessions were grown in the southeast U.S. from 2008 to 2009 and characterized for horticultural traits including biomass, foliage, plant size, flowering, and seed reproductive traits. Principal component analysis were applied to all traits for characterizing relationships among sunn hemp accessions for primary and secondary branches, open flowers, leaves, nodes, internodes, and seeds as well as diverse plant height, width, leaf area, apical dominance, and seed weight. The first three principal components had eigenvalues greater than 1.00, and together they explained 84% of the total variation occurring between these 16 sunn hemp accessions for this group of morphological, phenological, and reproductive traits. Apical dominance, flowering, seed number, total seed weight, open flowers, primary lateral branches, and nodes contributed mostly towards total variance in these sunn hemp populations. Cluster analysis separated sunn hemp accessions into two groups (clusters) based on low or high seed numbers. Sunn hemp accessions could be used as parents for hybridization and thus contribute to sunn hemp breeding.