Timely transition to flowering, maturity and plant height are important for agronomic adaptation and productivity of Indian mustard (B. juncea), which is a major edible oilseed crop of low input ecologies in Indian subcontinent. Breeding manipulation for these traits is difficult because of the involvement of multiple interacting genetic and environmental factors. Here, we report a genetic analysis of these traits using a population comprising 92 diverse genotypes of mustard. These genotypes were evaluated under deficient (N75), normal (N100) or excess (N125) conditions of nitrogen (N) application. Lower N availability induced early flowering and maturity in most genotypes, while high N conditions delayed both. A genotyping-by-sequencing approach helped to identify 406,888 SNP markers and undertake genome wide association studies (GWAS). 282 significant marker-trait associations (MTA's) were identified. We detected strong interactions between GWAS loci and nitrogen levels. Though some trait associated SNPs were detected repeatedly across fertility gradients, majority were identified under deficient or normal levels of N applications. Annotation of the genomic region (s) within ± 50 kb of the peak SNPs facilitated prediction of 30 candidate genes belonging to light perception, circadian, floral meristem identity, flowering regulation, gibberellic acid pathways and plant development. These included over one copy each of AGL24, AP1, FVE, FRI, GID1A and GNC. FLC and CO were predicted on chromosomes A02 and B08 respectively. CDF1, CO, FLC, AGL24, GNC and FAF2 appeared to influence the variation for plant height. Our findings may help in improving phenotypic plasticity of mustard across fertility gradients through marker-assisted breeding strategies.

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The present investigation was undertaken in F1 population of 36 crosses, obtained by crossing 18 inbred lines of soybean with two diverse testers in line × tester mating design during kharif 2012. All the parental lines and their F1 hybrids were evaluated in randomized complete block design at the Experimental Farm of Department of Crop Improvement, CSK HPKV, Palampur (HP ) during kharif 2013. The aim of this study was to identify suitable parents and hybrids for yield and its contributing traits. Experimental results revealed significant differences for lines, testers and line × tester for majority of the traits studied. Lines Bragg, Shivalik and P9-2-2 were found to be good general combiners for most of the traits. The cross combinations, Bragg × Hara Soya, DS-1213 × Hara Soya, H-330 × Hara Soya, PK-472 × Him Soya and H-330 × Him soya showed high per se performance and SCA effects for seed yield per plant and were rated as potential crosses for further improvement. Further, non-additive gene action (σD2) played a major role in the manifestation of almost all the traits which suggested the use of breeding approaches such as single seed descent method, reciprocal recurrent selection with one or two intermatings and diallel selective mating for the improvement of seed yield and related traits. Selection of parents based on their combining ability is an effective approach in hybrid breeding programme.

Aim: Identification of high breeding value donor lines harbouring tolerance to moisture stress from diversity stock of 443 genotypes of Brassica juncea. Methodology: Germplasm stock of 443 Indian mustard (Brassica juncea L.) genotypes, comprising introgression lines, land races, old cultivars and advance breeding lines, were evaluated under two environments viz., irrigated and rainfed conditions to check the variability for yield and related traits. Statistical software META-Rver 6.0 (Multi Environment Trial Analysis using R) was used for computation of Best Linear Unbiased Predictions, Analysis of Variance (ANOVA), Genetic Correlations and Heritability. Drought susceptibility index and per cent seed yield reduction under rainfed conditions were used as indicators to determine moisture stress tolerance in genotypes. Results: The variability for moisture stress tolerance has been unravelled in a diverse genetic stock of Brassica juncea under two environments: irrigated and rainfed. For high prediction accuracy, the ranking of genotypes was done based on Best Linear Unbiased Predictions for seed yield and its component traits. PBR-378, RGN-329, RB-73, RB-50 and PBR-422 and Giriraj were identified as moisture stress tolerant genotypes. One land race Sahib 36 and three introgression lines viz., MCP 12-211, PTJ-3-69 and MSC-3 have also been identified as potential genetic resources for moisture stress tolerance. Principal component analysis based on biplots depicted specific distribution of variables for each environment. Interpretation: This study led to the identification of potential donors for moisture stress tolerance with high predictive accuracy. Low drought susceptibility index and high breeding value in a land race and three introgression lines derived from Erucastrum cardaminoides, B. tournefortii and B. carinata emphasized their utilization as potential genetic resources to breed for moisture stress tolerance in B. juncea.

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