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Not AvailableThe present study aimed to estimate the genetic diversity; variability and heritability in 64 castor genotypes for root, shoot and water use efficiency (WUE) traits and further identify the suitable genotypes for a drought resistance breeding programme. Characters like plant height, leaf area index (LAI), stem girth and total dry matter (TDM) were significantly correlated (>0.70) with root volume and root dry weight. The genotypes were ranked based on the index in ascending order considering five important characters viz; LAI, stem girth, root volume, root dry weight and TDM using principal component analysis and 15 genotypes with high performance in terms of shoot and root characters were selected. These genotypes comprised 48-1, RG 2124, RG 2169, RG 2155, RG 2074, GCH-5, RG1963, RG 2094, DCS-99, RG 2153, DCS-78, RG 27, RG 1618, RG 2147 and RG 1673. High general combining ability (GCV) and heritability (>80%) for plant height, root volume, root dry weight, TDM and LAI indicate sufficient variability for selection for these characters. Heterosis was high for TDM, root dry weight, volume and LAI. Superior heterobeltiosis was observed for TDM, root volume and root dry weight. The hybrid GCH-5 with its significant heterosis, heterobeltiosis and standard heterosis for key root traits like root volume, root dry weight and TDM is worth exploring under water scarce conditions.Not Availabl