Genetic diversity analysis of mustard (Brassica juncea L.) under protected and unprotected conditions at Bijapur, Karnataka

Genetic diversity employing Mahalanobis D² statistics was studied for 46 germplasm lines of Indian mustard under protected conditions (chemical control against pest and diseases) at Bijapur during rabi season of 2007–08. The 46 genotypes were grouped into seven clusters based on D² analysis. The intra cluster distance varied from 0.00 (cluster VII) to 13.606 (cluster III) in protected condition, and 0.00 (cluster VII) to 12.924 (cluster II) under unprotected condition. Similarly intercluster distance varied from 20.998 (cluster VI) to 294.474 (cluster II) in protected condition, and under unprotected condition from 17.572 (cluster VI) to 277.847 (cluster V). Number of secondary branches per plant showed maximum per cent contribution towards divergence followed by biological yield per plant, days to maturity and seed yield. Identification of similar cluster combinations inculcated both quantitative and qualitative traits in a positive direction for more effective selection.