Singh, S.P.Singh, Rahul2023-04-132023-04-132022https://krishikosh.egranth.ac.in/handle/1/5810196389Rice is a major cereal crop rich in starch, carbohydrates but deficient in major micronutrients such as iron and zinc content in grains. The population solely depends on rice based food for their calorific supply suffers from malnutrition and several health impairments termed as hidden hunger. A small increase in iron and zinc density in rice variety using plant breeding methods and procedure can be able to improve socio-economic condition of the peoples. Primary and basic step to develop such a miracle variety is to identify and mapping the linked QTLs. Thus present investigation was aimed to map the QTLs linked with grain iron and zinc content in F2 mapping population derived from selfing of true F1 cross made between Samba Mahsuri (female parent) and Sathi (male parent) at Bihar Agricultural University Sabour, Bhagalpur, Bihar. Ten morphological and two qualitative (grain iron and zinc content) data were recorded from each individual plant separately from the F2 mapping population. All the recorded data were subjected to descriptive analysis and correlation analysis. Whereas for genotyping, selective genotyping was used in which a distribution curve were constructed using grain iron and zinc data recorded from 192 F2 population including parents. Of this population selective genotyping were carried out using 47 genotypes from lower tail of distribution and 47 genotypes from upper tail of distribution along with both parents. In total 96 genotypes including parents were used to generate genotypic data using parental polymorphic molecular markers. Both phenotypic (grain iron and zinc content) and genotypic data were subjected to QTL analysis using QTL Cartographer software. The finding of descriptive analysis of present investigation revealed that number of filled grains per panicle, grain yield per plant, days to fifty percent flowering, plant height, grain zinc content, number of effective tillers per plant and grain iron content showed range value in their descending order. Positive skewness was recorded for number of effective tillers per plant, grain length-breadth ratio, thousand grain weight, grain zinc content and grain yield per plant. While negative skewness was recorded for days to fifty percent flowering, plant height, panicle length, grain breadth and grain iron content. Number of filled grains per panicle, grain length-breadth ratio, grain zinc and iron content were found to be platykurtic nature of distribution. Significantly and negative correlation were found for grain iron and zinc content with plant height, number of effective tillers per plant, number of field grains per panicle and grain yield per plant, whereas significantly positive correlation with each other. Grain yield per plant exhibited significantly positive correlation with plant height, number of effective tillers per plant and number of field grains per panicle. Transgressive segregants were observed for grain iron and zinc content in the segregating population. In addition, QTL analysis was carried out using single marker analysis and composite interval mapping. Single marker analysis detected 19 markers linked with grain zinc content from which six markers namely, OSZIP1, RM475, OSZIP3B, RM20, RM141 and RM12 located on the chromosome 1, 2, 4, 12.1, 12.2 and 12.4 showed higher phenotypic variance 11.79%, 19.83%, 8.13%, 12.79%, 15.6% and 15.9% with LOD value 11.79, 20.77, 7.97, 12.87, 15.98 and 16.30, respectively. Similarly, Single marker analysis detected 5 markers linked with grain iron content from which 3 markers RM475, RM320, and RM441 located on the chromosome 2, 7 and 11 and showed phenotypic variance of 7.49%, 5.2% and 6.47% with LOD value 7.32, 5.02 and 6.29, respectively. Composite interval mapping identified one novel QTL for grain zinc content namely qZn2.1 on the chromosome 2 flanked with marker RM301-RM475. QTL qZn2.1 showed phenotypic variance of 8.02% with LOD value 5.14. However, composite interval mapping identified 2 novel QTLs for grain iron content namely qFe2.1 and qFe12 on the chromosome 2 and 12 flanked with marker RM301-RM475 and RM141-RM235, respectively. QTL namely qFe2.1 and qFe12 showed phenotypic variance 28.74% and 34.52% with LOD value 8.79 and 9.1, respectively. Further fine mapping of QTLs in advanced line for grain iron and zinc content may be helpful in improving nutrient density in rice variety using marker assisted selection. Additionally, positive correlation between grain iron and zinc content leads to simultaneous improvement for both the traits.EnglishThesis