Abstract Water calamity results in the screening of drought tolerant genotypes which were suitable for both non-irrigated as well as in irrigated condition. Keeping consideration over this experiment was designed to study genetic variability and heritability under non- irrigated and irrigated condition on some morphological and quality traits an experiment on Indian mustard (Brassica juncea L.Czern & Coss), was conducted by accommodating 20 genotypes, from various Rapeseed & Mustard centres located across country, randomly in three replications during Rabi 2016-17 in Randomized Complete Block Design (RBCD), one subjected to a drought regime inside the Rainout shelter under nonirrigated condition which was also devoid of rainfall and another one provided with normal irrigated field condition in Dr. Rajendra Prasad Central Agricultural University , Pusa, Samastipur. Analysis of variance for the studied traits revealed considerably exploitable variability. Out of 20 genotypes under both non-irrigated as well as irrigated condition, Rajendra Suphalam showed tolerance towards water stressed condition and performed well in terms of productivity in an irrigated situation for all the traits. PKRS-28 identified as tolerant genotype under non- irrigated, and Pusa Mahak as well suited under an irrigated condition in terms of flowering – maturity, siliqua characteristics and yield contributing traits. Under both conditions, high heritability coupled with high GAM for traits namely, HFPB and SBP-1 which were indicative of preponderance of additive gene action for expression of these traits hence are acquiescent for simple selection. The height of first primary branch and secondary branches per plant due to wide variability, meagre environmental influence along with high heritability and genetic advance suggested the exploitation of these traits for the further breeding programme as these traits are fixable in nature can be utilized in further segregating generations.The initiation of primary branches from the lowest position of the plant can accommodate number of branches and also provides a way to utilize the non- usable portion of the mustard plant from the base up to 55-60 cm.