Inheritance of Certain Morphological Characters and Capsule Borer Resistance in Castor (Ricinus communis L.)
Sathishkumar R.
Department of Genetics and Plant Breeding, University of Agricultural Sciences, GKVK, Bengaluru - 560 065, India and ICAR-Indian Institute of Oilseeds Research, Rajendranagar, Hyderabad – 500030, India.
Arun Kumar, M. *
Silkworm Seed Production Centre, Central Silk Board, Jorhat, Assam- 785 005, India.
Nehru, S. D.
Department of Genetics and Plant Breeding, University of Agricultural Sciences, GKVK, Bengaluru - 560 065, India.
*Author to whom correspondence should be addressed.
Abstract
Aim: The Shoot and Capsule Borer (SCB), also known as the yellow peach moth (Conogethes punctiferalis), is a major pest of castor, causing significant yield losses by damaging the plant's inflorescence (spike). This study was conducted to precisely determine the relationship between morphological features (inflorescence morphology) and the incidence of Shoot and Capsule Borer (SCB) and to study the inheritance pattern.
Study Design: Randomized complete block design with two replications were followed.
Place and Duration of Study: The experiment was conducted in ICAR- Indian Institute of Oilseeds Research (IIOR), Hyderabad, India, during 2022-2023.
Methodology: In August 2023, the P1, P2, F1, F2, BC1P1, and BC1P2 generations of the DCS-9 × RG-2774 cross was planted at ICAR-IIOR. These generations were replicated twice. The number of plants observed varied across generations, with 60 plants from the parental generations, 280 from the F2 generation, and 60 each from the F1, BC1P1, and BC1P2 generations. Data were recorded on per cent capsule borer damage and on the Spike morphological characters. The genetic variability and inheritance were calculated.
Results: The trait percent capsule borer incidence exhibited high phenotypic (PCV = 49.17%) and genotypic (GCV = 41.16%) coefficients of variation, indicating considerable variability within the population. High heritability (70.70%) coupled with high genetic advance (70.35%) was observed. Point-biserial correlation analysis revealed a significant positive association between spine on capsules and capsule damage (r = 0.360), as well as between presence or absence of bloom and capsule damage (r = 0.270). Spininess of capsules appeared to be a codominant trait, while compactness of the spike showed evidence of dominance. The continuous distribution observed in the F2 population supports the quantitative nature of capsule borer resistance, indicating that the trait is likely governed by multiple genes.
Conclusion: This genetic variability and inheritance pattern provide a strong basis for developing castor lines with improved resistance to the capsule borer.
Keywords: Castor, host plant resistance, coefficients of variation, polygenic