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2016 - 20192
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Subject: Genetics and Plant Breeding × Author: Adhikari, Sneha × Type: Thesis ×
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    ThesisItemOpen Access
    Characterization and QTL mapping of Teosinte derived maize population for BLSB resistance and other traits
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2019-08) Adhikari, Sneha; Singh, N.K.
    The investigation was carried out with the aim to map genomic region for resistance to banded leaf and sheath blight and other traits. The field experiments were conducted during rabi 2016-2017, kharif 2017, rabi 2017-18 for development of mapping population while kharif 2018 season was used for phenotyping of BC1F5 mapping population under artificially inoculated with Rhizoctonia solani and control conditions. Among BC1F3 and BC1F4 generation of teosinte derived maize population, large phenotypic variation was observed for all morphological traits, hence teosinte can be used for enhancing maize germplasm. Of the 126 lines 76, 20 and 21 lines were of protogynous behaviour, short ASI (0-1 days) and bears > 3 ears per plant, respectively in both BC1F3 and BC1F4 generations. Jaccard similarity coefficients and dendrogram generated using SSR markers data indicate 25 percent genetic similarity in maize and teosinte. Analysis of variance showed highly significant variation among the BC1F5 lines for disease reactions and other traits. Among 169 BC1F5 lines, 9 (MT-25, MT-90, MT-99, MT-128, MT-136, MT-144, MT-145, MT-148, MT-152) comes under the category of moderately resistant class and can be utilize in maize BLSB resistance breeding. Analysis of variance (ANOVA) revealed significant variance between the environment for days to anthesis and silking, anthesis-silking interval (ASI), flag leaf length, flag leaf width, ear per plant, ear length, ear diameter, kernel rows per ear, kernels per row, test weight and grain yield per plant. It indicates greater impact of disease stress on these characters. Correlation analysis exhibited significant correlation of BLSB resistance with flag leaf angle, plant height, ear length, ear diameter, kernel rows per ear, kernels per row, test weight and grain yield per plant. The single-marker ANOVA revealed a total 125 QTLs, of these 4 were major and 121 were minor QTLs for 14 traits. These QTLs were distributed over 10 chromosomes with phenotypic variation ranges from 2.29 to 12.98 per cent. Out of 125 QTLs, 64 and 61 QTLs were detected in E1 and E2, respectively and of which 20 QTLs were common in both the environments. Maximum QTLs were detected in chromosomes 4 and 9 followed by 7, 6, 10, 5, 2, 1, 3 and 8. Consistent QTLs across the environments were identified for days to anthesis (3), days to silking (2), flag leaf length (1), flag leaf width (1), plant height (2), ears per plant (1), node bearing first ear (2), ear length (2), ear diameter (1), kernel rows per ear (3), test weight (1) and grain yield per plant (1). The single-marker ANOVA analysis revealed one major QTL on chromosome 5 and four minor on chromosomes 1, 3, 4 and 8 for BLSB resistance under DE1. In DE2 however only four minor QTLs one each on chromosomes 1, 3, 5 and 8 were identified. Out of these nine QTLs two were identified across the environments that were linked with markers umc1500 and phi10918, considered as stable QTLs. Among seven identified QTLs for BLSB resistance, a major QTL linked with phi10918 was colocalized with three minor QTLs for ear length, kernel rows per ear and kernels per row. Seven minor QTLs for days to anthesis, days to silking, ear length, ear diameter, kernel rows per ear, kernels per row and grain yield per plant were co-localized with a minor QTL for BLSB resistance that linked with marker umc1720. One minor QTL for BLSB resistance that was linked with phi420701 was collocated with a major QTL for plant height. Remaining two minor QTLs for BLSB resistance namely, umc1500-linked QTL and umc2000-linked QTL were colocalized with QTL for test weight and ear per plant, respectively. The investigation successfully identified lines with desirable traits that can be utilized in stress resistance breeding. Co-localized QTLs identified for various morphological traits and disease resistance can integrate/pyramid in breeding materials for improving BLSB resistance.
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    ThesisItemOpen Access
    Studies on selection parameters, combining ability and heterosis for seed yield and its components in Indian mustard (Brassica juncea L. Czern & Coss)
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2016-06) Adhikari, Sneha; Pant, Usha
    The present investigation was carried out with the aim to study selection parameters, combining ability, extent of heterosis for various quantitative characters in Brassica juncea (L.) Czern & Coss. The experimental material for present study comprised of a set of 10 genotypes of Indian mustard (Brassica juncea L.) of diverse origin involving two genotypes suitable for early sown (PRE-2011-15, PM-2), six for timely sown (Divya-55, Maya, DRMR-675-39, RRN-778, RB-57 and RMM-09-4 ) and two for late sown (PRL-2012-13, NRC-HB-101) situations. Crosses were made between these genotypes in all possible combinations excluding reciprocals during rabi 2014-15. The parents and their 45 F1‟s along with one standard variety (Kranti) were evaluated in a randomized block design with three replications during rabi 2015-16 at N. E. B. C. R. C., GBPUA& T, Pantnagar. The combining ability analysis was performed by following Griffing‟s (1956) method 2, model I. Results of ANOVA showed that the mean squares due to gca and sca were highly significant for all the characters. The magnitude of later being higher than former except for length of main raceme, seed yield per plant and glucosinolate content indicating predominance of non-additive gene action for the expression of the all the characters whereas, additive gene action was predominant for length of main raceme, seed yield per plant and glucosinolate content. The broad sense heritability h2b was high (>0.50) for glucosinolate content followed by seed yield/ plant, number of siliquae on main raceme, days to maturity, number of secondary branches/plant, number of primary branches/plant, siliqua density on main raceme, oil content and test weight and, medium (0.25 to 0.50 ) for rest of the characters. Genetic advance (GA) ranged from 0.043 for siliqua density to 4.929 for plant height. Higher heritability was associated with higher genetic advance under selection for glucosinolate content, seed yield/ plant (g) , number of siliquae on main raceme, number of secondary branches/plant and days to maturity. Predictability ratio was lower than unity for all the character under study, it represented the involvement of non-fixable type of variance so in such characters the heterosis breeding appears to be the best option. Average degree of dominance showed over dominance for all the character under study The estimates of 2s were found to be higher than the 2g for all characters. The estimates of 2 A and 2D indicated that the magnitude of later was higher than farmers indicating the presence of non-fixable type of gene action. The narrow sense heritability h2n was medium (0.30-0.10) for seed yield/ plant, length of main raceme, glucosinolate content, test weight, oil content, days to maturity, number of primary branches/plant, length of siliqua and number of siliquae on main raceme and low (<0.10) for remaining characters. Moderate to low h2n was due to low estimate of additive genetic variance. Based on significant GCA effects in desirable direction, the parents PM-25(-3.04**) for early maturity; Maya (- 7.25**) for dwarf plant height; PRL-2012-13 (1.703**) for seed yield per plant; RRN-778 (1.007**), for oil content and Divya-55 (-32.604**) for low glucosinolate content were found the best parents for respective traits. The study revealed that crosses PRL-2012-13×Divya-55 (-19.33**) for early maturity; RRN-778×PM-25 (-33.11**) for dwarf plant height; Divya-55×RRN-778 (4.14**), for seed yield, PRE-2011-15×RMM-09-4 (3.82**) for oil content and RRN-778×RMM-09-4 (-69.01**) for low glucosinolate content were the most outstanding crosses based on SCA effects. The evaluation of heterosis revealed that heterotic combinations RRN-778×Maya (-5.660*), RRN-778×Maya (7.41**), RB-57×Maya (-20.741**) for early maturity; Maya×RMM-09-4 (24.48**), RB-57×PM-25 (43.64**) and PRL2012-13xDRMR-675-39 (142.57**) for seed yield, PRL-2012-13×RRN-778 (3.22**), PRL-2012-13×RRN-778 (3.58**), DRMR-675-39×Maya (6.28**) for oil content showed maximum relative, better and economic heterosis respectively. Overall results indicated the advantage of heterozygosity perhaps due to predominance of non-additive gene effects. Promising parents have been identified based on GCA effects for different characters and outstanding crosses were identified based on SCA effects as well as expression of heterosis.