Evaluation of Agronomic Traits and Genetic Relationships among Elite Breeding Lines of Castor (Ricinus communis L.)

Aims: To evaluate genetic variability, heritability, and trait associations among 50 elite castor breeding lines and two check varieties to identify key agronomic traits for improving seed yield and oil content. Study Design: Augmented randomized complete block design. Place and Duration of Study: Narkhoda research farm, ICAR - Indian Institute of Oilseeds Research, Hyderabad, India, during the kharif season of 2024. Methodology: Fifty advanced breeding lines and two check varieties (PCS 262 and DPC-9) were assessed for eleven agronomic traits, including days to 50% flowering, plant height, primary spike length, and seed yield. Data were collected from five plants per genotype, and statistical analyses included ANOVA, genotypic and phenotypic coefficients of variation (GCV, PCV), heritability, genetic advance, and correlation analysis using INDOSTAT version 9.1. Results: High GCV and heritability were observed for seed yield per plot (GCV: 22.06%, heritability: 86.44%), capsules per primary spike (27.25%, 81.56%), and primary spike length (18.53%, 96.93%), indicating strong potential for selection. Seed yield was positively correlated with spike length (r = 0.467**, P < 0.01) and oil content (r = 0.301*, P < 0.05), while negatively correlated with days to 50% flowering (r = -0.285*, P < 0.05). Conclusion: The study highlights significant genetic variability and strong trait associations, particularly for primary spike length, capsule number, and seed yield, which can be effectively prioritized in castor breeding programs to develop superior, high-yielding varieties or hybrids with high oil content. These findings are especially important given the industrial relevance of castor oil, which is a unique non-edible oil with high ricinoleic acid content, making it a vital raw material for over 700 industrial products. Castor oil is extensively used in the manufacture of bio-lubricants, polymers, plastics, paints, adhesives, surfactants, cosmetics, and pharmaceuticals, as well as in the production of biodiesel and other eco-friendly alternatives.