143 Journal of Oilseed Brassica, 8 (2) July, 2017 Assessment of genetic variation among drought tolerant recombinant inbred lines (RILs) of Indian mustard (Brassica juncea L.) PK Rai, Supriya Ambawat*, Neeraj Gurjar, VV Singh and Subaran Singh ICAR-Directorate of Rapeseed-Mustard Research, Sewar, Bharatpur-321 303, Rajasthan, India *Corresponding author: supriya_bmb@yahoo.co.in (Received: 11 Jan 2017; Revised: 27April 2017; Accepted: 26 May 2017) Abstract The present study reveals the genetic variation among 225 Recombinant Inbred Lines (RILs) derived from the cross Rohini X PBR-97 which were evaluated under normal and water stress conditions. Significant genetic variation was observed for plant height, main shoot length, fruiting zone length, siliqua length, biological yield/plant, harvest index, seed yield/plant, fibre, phenol, days to flowering under normal conditions while plant height, main shoot length, fruiting zone length, siliqua length, seed/siliqua, harvest index, phenol, days to flowering were found to be significant under drought conditions. Heritability estimates were high (>70%) for main shoot length, siliqua length, seed yield/plant, and phenol content. Seed yield per plant was significantly and positively correlated with plant height (0.37**), main shoot length (0.19*), fruiting zone length (0.16*), siliqua length (0.19*), seeds/siliquae (0.16*), biological yield per plant (0.45**) and harvest index (0.61**) and negatively correlated with oil content (-0.13), fibre (-0.28**). Further, 25 promising RILs were identified based on seed yield/plant which can further be used in brassica improvement breeding programmes to develop drought tolerant brassica varieties. Key words: Brassica juncea, biochemical, correlation, drought stress, morphological, water deficit Journal of Oilseed Brassica, 8 (2) : 143-150, July 2017 Introduction Rapeseed-mustard group of crops is very important rabi oilseed and occupies a prime position due to its high oil content and ability to withstand fluctuating environmental conditions. Of these, Indian mustard [Brassica juncea (L.) Czern & Coss.], popularly known as ‘raya’ or ‘laha’ is a major rabi oilseed crop in India (Singh et al ., 2016). Although a momentous success has been achieved in improving the production and productivity of Indian mustard during the last two decades, its domestic edible oil demand has not been met out fully. Thus, further improvement in the productivity of Indian mustard is an important breeding objective. It possesses enormous genetic variability for seed and drought tolerance characteristics which further leads to the genetic diversity. The genetic variability is the basic requirement for improving crops which further leads to progress in crop breeding. Thus, there are good chances to improve this crop by evaluating and utilizing genetic variation (Ullah et al., 2016). The information on the nature and magnitude of variability for different morphological and biochemical parameters is necessary to judge the potentiality of particular genotype. In India, it is mostly grown on light textured soils as a rainfed crop and therefore later it results into drought stress during its reproductive stage (Kumar and Singh, 1998). Thus, development for drought resistance becomes the main objective for this crop (Singh and Choudhary, 2003). Drought is most serious problem for global agriculture, approximately affecting 40% of the world’s land area (UN Environment Management Group 2011). The changing global climate scenario is definitely going to effect the crop growth and productivity by raising the temperature which will ultimately lead to severe drought stress causing alternations in metabolism and gene expression of crop plants (Mir et al., 2012). Thus, understanding plant responses to drought is the need of the hour so that stress tolerant crops can be developed to increase area and yield of the