~ 372 ~ Journal of Pharmacognosy and Phytochemistry 2018; 7(4): 372-379 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2018; 7(4): 372-379 Received: 01-05-2018 Accepted: 05-06-2018 Arpna Kuma Assistant Professor, Department of Crop Improvement, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, Himachal Pradesh, India Vedna Kumari Department of Crop Improvement, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, Himachal Pradesh, India Correspondence Arpna Kuma Department of Crop Improvement, College of Agriculture, CSK Himachal Pradesh Krishi Vishvavidyalaya, Palampur, Himachal Pradesh, India Exploitable genetic variability and character association studies under changing climate in mid-hills of north-west Himalayas in Indian mustard [ Brassica juncea (L.) Czern. & Coss.] Arpna Kumari and Vedna Kumari Abstract In order to assess the nature and extent of genetic variability and inter-relationships among seed yield and related traits, an experiment was conducted at CSKHPKV, Palampur during rabi 2008-09 and 2009-10. The pooled analysis of variance over the environments indicated that the mean squares due to genotypes were significant when tested against mean squares due to g x e interactions for characters CGR (GS3), RGR (GS3), NAR (GS3), LAR (GS2), SLW (GS2), days to flower initiation, days to 50 per cent flowering, days to 75 per cent maturity, plant height, siliqua length, 1000-seed weight and harvest index. The g x e interactions were significant for RGR (GS2), days to flower initiation, number of secondary branches per plant, siliquae per plant, length of main shoot, siliquae on main shoot, seeds per siliqua, seed yield per plant, biological yield per plant and harvest index indicating that genotypic differences recorded in individual environments had vanished for these characters. The mean values of the characters studied showed a wide spectrum of genetic variation and characters such as LAR, LAI, LAD, SLW, days to flower initiation, seeds per siliqua, 1000-seed weight, seed yield per plant, biological yield per plant and harvest index recorded excellent potential. On the basis of mean performance, Geeta and RH-8544 were found to be promising genotypes for seed yield and biological yield per plant. RH-8544 also exhibited resistance to white rust. The phenotypic correlation coefficient revealed significant positive associations of CGR (GS2), LAI (GS2), SLW (GS2), plant height, number of primary branches per plant, number of secondary branches per plant, siliquae per plant, length of main shoot, siliquae on main shoot, biological yield per plant and harvest index with seed yield per plant. The path coefficient analysis revealed that biological yield per plant and harvest index exhibited positive and high direct effects on seed yield per plant. Therefore, these characters could be considered as the best selection parameters for the improvement of seed yield per plant. Keywords: Brassica juncea, genetic variability, correlation, path coefficient analysis, seed yield Introduction Oilseeds occupy an important position in Indian agricultural economy and daily diet, being a rich source of fats and vitamins. India is among the major oilseed producing countries with around 7 per cent contribution in the global production. Indian mustard [Brassica juncea (L.) Czern. & Coss.] is second largest oilseed crop in India after soybean contributing about 80 per cent of the total rapeseed-mustard. India accounts for 21.7 per cent of the total global acreage and contributes 10.7 per cent to total production (USDA, 2016) [26] . In spite of all the efforts made over past few decades, the productivity has remained almost constant due to lack of high yielding genotypes with stable performance over the environments. The success in any breeding programme depends upon the nature and magnitude of genetic variability which provides better chances of selecting desired types. The knowledge of inter-relationships between different traits is important in breeding for direct and indirect selection of characters that are not easily measured and those with low heritability. Economic characters, such as seed and oil yields are controlled by many genes and have a complex type of inheritance. The progress of breeding for such economic traits is thus, determined by the nature and magnitude of their genotypic and environmental variability. The components which have high heritability and positive correlation with yield can be used in the indirect selection for yield and act as an alternate mode of selection for yield improvement. When the indirect associations become complex, path coefficient analysis is the most effective mean to find out direct and indirect causes of association among the different variables. Keeping this in view, the present study was conducted to investigate the extent of genetic