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Thesis

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2020 - 20212
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Subject: Genetics and Plant Breeding × Author: Harpreet Kaur × Start date: 2000 ×
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    ThesisItemOpen Access
    Genome-wide association mapping for Fe, Zn and yield traits in pigeonpea
    (Punjab Agricultural University, Ludhiana, 2021) Harpreet Kaur; Inderjit Singh
    In the present study, an effort was made to understand the complex nature of yield and quality traits and genome-wide association studies (GWAS) was undertaken to identify QTLs associated with traits. The analysis of variance (ANOVA) revealed significant variation among all genotypes in both the years and pooled data. Measurement of skewness and kurtosis indicated presence of duplicate and complementary gene interaction for different traits. The seed yield exhibited highly positive and significant correlation with number of primary branches per plant, number of secondary branches per plant and number of pods per plant for both the years and pooled data across two years. Path analysis identified pods per plant, number of primary and secondary branches as the major contributing traits to grain yield in both the years and pooled data. Yield per plot and pods per plant exhibited high heritability along with high genetic advance showing additive gene effect and could be considered during selection. In genotypic analysis, a total of 7366 filtered SNPs were used for genome-wide association studies through ddRAD-Seq. A total of 30 highly significant associated SNPs in 2018-19, 23 significant associated SNPs in 2019-20 and 25 significant associated SNPs in pooled data were identified through combination of two or more than two models for different traits. Most of the SNP loci were found to be environment and trait specific but few stable and consistent SNPs were identified. Some of the SNPs associated with days to maturity, yield per plot and grain iron content were observed to be consistent in 2018-19 and pooled conditions. The candidate regions were defined by the average LD decay distance or the LD block. Biological function of the identified candidate genes revealed their role in plant growth and development, organogenesis, pollen development and source-sink relationship. These genes were found to be present on chromosome 02, 03 and 09. Three polymorphic KASP markers for traits viz., grain iron content, number of primary branches and yield per plot were validated and showed that parents have homozygous alleles for the traits and alleles were found to be segregating in the F2:3 population. Promising genotypes for grain iron, grain zinc content and yield attributing traits were identified which can be used as donor parents in pigeonpea breeding programme and developed markers can be used in marker assisted selection (MAS) for identifying desirable genotypes having allele of interest.
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    ThesisItemOpen Access
    Performance of inbred lines and their hybrids in maize for protein quality and β-carotene
    (Punjab Agricultural University, Ludhiana-, 2020) Harpreet Kaur; Gill, Gurjit Kaur
    Maize (Zea mays L.) is an important cereal crop for livestock, feed and nutrition, worldwide. Sixty hybrid combinations of maize were generated through Line x Tester mating design using fifteen lines of LM13 versions and four testers of LM14 versions as parental material along with two standard checks PMH1 and HQPM to study combining ability, heterosis and Genotype x Environment interactions. The parents, hybrids were evaluated along with two standard checks during kharif 2018 and spring 2019 at Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana and Regional Research Station, Gurdaspur. Data for eight agronomic and five biochemical parameters were recorded. The mean sum of square due to year, location, genotype, parents, crosses and parents vs crosses for all agronomic traits were significant except days to maturity as well as for all biochemical traits except starch content. Among female line 13CLO-6, 13CLO-14, 13CLO-15 and 13CLO-16 were good combiner for ear length, ear girth, yield per plot, 1000 kernel weight and shelling %. Among the testers, 14CLO-1 and 14CLO-3 were found good combiner for all yield and yield contributing traits. For biochemical traits, line 13CLO-5 was good combiner for tryptophan, starch and oil content,13CLO-15 was good combiner for protein and β- carotene content. Tester 14CLO-3 was good combiner for tryptophan and β- carotene. Among crosses viz., (L9 X T2, L12 X T2, L14 X T3, L4 X T4, L8 X T4 and L13 X T4) were having significantly better specific combining ability effects for days to maturity, ear length, ear girth, yield per plot,1000 kernel weight and shelling %. Crosses viz., (L1 X T1, L6 X T2, L3 X T4, L14 X T2, L11 X T3 and T8 X T4) were also significantly better specific combiner for biochemical traits like protein, tryptophan and β- carotene contents. Top five crosses were (13CLO-3 X 14CLO-4, 13CLO-14 X 14CLO-3, 13CLO-15 X 14CLO-4, 13CLO-6 X 14CLO-2 and 13CLO-2 X 14CLO-4) having significant and desirable SCA effects and heterosis for most of the traits indicating potential to exploit hybrid vigour for breeding programme. All the converted lines, testers and hybrids showed the presence of crtRB1 and o2 genes at 543 bp band and 150 bp band respectively. The validity of the results promises that the hybrids generated are nutritionally enriched.