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IntroductionIndian mustard (Brassica juncea) is a naturally autogamous species, yet in this crop frequent out-crossing occur which varies from 5 to 30% depending upon the environmental conditions and random variation of pollinating insects. Cytologically Indian mustard is an amphidiploid (2n=36), derived from interspecific cross of Brassica campestris (2n=20) and Brassica nigra (2n=16) followed by natural chromosome doubling. These relationships have been confirmed by the artificial synthesis of amphidiploids species by hybridizing basic diploid species and also by analysis of chloroplast and mitochondrial DNA restriction pattern of basic and amphidiploids International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 5 (2017) pp. 942-953Journal homepage: http://www.ijcmas.comHalf diallel analysis of eight parents was carried out to identify the high heterotic crosses and their relationship in terms of general and specific combining ability (gca & sca) in Brassica juncea L. Czern and Coss. Mean squares due to parent v/s crosses were also significant for all the traits which depicted presence of heterosis for all the traits, except for days to maturity, plant height, siliquae on main shoot, number of seeds/siliqua, siliqua length and oil content in timely sown condition and for plant height, number of primary branches per plant, siliqua on main shoot and 1000 seed weight in late sown condition. The heritability in narrow-sense showed the prevalence of additive variance for siliqua length, days to maturity, number of primary branches per plant in late sown condition, while for other traits an appreciable proportion of total variance was non-additive in both the environments. In the present study, an overall appraisal of GCA effects revealed that RH0735 and BPR349-9 in normal environment and RH0116 and RH0555A in late sown environment were good general combiner for majority of the characters. High GCA effects are related to additive gene effects or additive x additive interaction which represent the fixable genetic component of variation. Hence these parents could be efficiently used for exploiting seed yield. For seed yield the crosses RH8814 x RH0555A, RH0644 x BPR543-3 and BPR349-9 x RH0644 in timely sown condition and crosses RH0555A x RH0644, RH0735 x RH0116 and BPR349-9 x RH0644 were identified as promising on the basis of their high per se performance and with high significant SCA effects. These crosses could be extensively used in breeding programme to develop superior segregants and the parents involved may be converted to well adapted cytoplasmic male sterile or restorer lines in further breeding programmes.

Principal component analysis was carried out with 20 morphological traits (including quantitative as well as qualitative) among 96 germplasm lines of Indian mustard [Brassica juncea (L.) Czern & Coss.]. Principal factor analysis led to the identification of eight principal components (PCs) which explained about 70.41% variability. The first principal component (PC1) explained 16.21% of the total variation. The remaining PC's explained progressively lesser and lesser of the total variation. Varimax Rotation enabled loading of similar type of variables on a common principal factor (PF) permitting to designate them as yield factor, maturity factor and oil factor etc. Based on PF scores and cluster mean values the germplasm accessions viz., RC2, RC32 and RC51 (cluster I), RC95 and RC96 (cluster X) were found superior for seed yield/plant and yield related factors like primary and secondary branches/plant; while the accessions RC34, RC185 and RC195 (cluster III) and RC53 (cluster VIII) were found superior for oil content. These accessions may further be utilized in breeding programmes for evolving mustard varieties having high seed yield and oil content. Hierarchical cluster analysis resulted into ten clusters containing two to 26 accessions. The results of cluster and principal factor analyses were in confirmation of each other.

A total of sixty genotypes and germplasm lines were evaluated and characterized for 14 quantitative and 8 qualitative traits in Brassica juncea. Observations were recorded on the basis of scores given in the DUS descriptor. Majority of accessions were very late in maturity and medium in flowering. No variability was observed for leaf length and leaf width. On the basis of branches, most of the genotypes were classified under intermediate category. Long main shoot length (31), medium number of siliquae on main shoot (46), medium density on main shoot (52), short siliqua length (51), very tall plant height (38), few numbers of seeds per siliqua (33), medium 1000-seed weight (38), medium seed yield per plant (32) and low oil content (40) were observed in most of the genotypes. For qualitative traits, most of the genotype showed dark green leaf color, sparse hairs, dentation of leaf margin lyrate type, open leaf growth habit, yellow petal color, semi-appressed siliqua angle with main shoot and intermediate siliqua surface texture. Wide (Yellow, Dull grey, Reddish brown, Brown and Black) diversity has been observed for seed color.

Eight diverse mustard genotypes namely RH8814, RH0735, RH0116, BPR349-9 RH0952, RH0555A, RH0644, BPR543-3 were selected as parents on the basis of their origin, adaptability, diversity and yield potential. Crosses were attempted during Rabi, 2013-14 in a diallel fashion (excluding reciprocals). Eight parents along with 28 F1s were evaluated during Rabi, 2014-15 in randomized block design with three replications