Gill, B. S.Khosla, Gaurav2018-09-222018-09-222018http://krishikosh.egranth.ac.in/handle/1/5810073947Two hundred and seventy five lines from seven different crosses of soybean derived from four different breeding methods viz. pedigree method (PM), single pod descent with selection (SPDS), single pod descent (SPD) and bulk method (BM) were used to assess the efficiency of breeding methods. Based on different yield contributing traits, bulk method was the best method in terms of mean of all lines over two years followed by pedigree method. When the yield of the highest yielding line from each method within each cross was compared with the best check mean, it was observed that the bulk method had the highest yielding line in three out of seven crosses whereas in four crosses it was ranked second. This performance was closely followed by pedigree method. Molecular assessment of the breeding methods was done based on the dissimilarity coefficient among lines within a breeding method using SSR primers. Based on the dissimilarity coefficients, number of unique lines in each breeding method were calculated. SPD method had the highest per cent of unique lines among all the methods in all the crosses. PM and BM had the lowest number of unique lines. Comparison of lines derived from bi-parental and multi-parental crosses revealed that biparental crosses having distantly related parents generated high yielding lines as compared to the multiparental crosses as well as the biparental crosses with less diverse parents. For mapping for YMD resistance genes and seed weight QTL, F2 plants from the cross SL 958 x AGS 456 were used. Segregation ratios in F2, BC1F1 and BC1F2 populations suggested that YMD resistance is controlled by two genes in inhibitory gene action. A total of 269 SSR markers were used for polymorphic studies and the identified polymorphic primers were used for genotyping studies. Bulk segregant analysis was performed with 114 polymorphic markers. Out of 114 markers, 13 markers showed polymorphism in resistant and susceptible bulks. Nine markers were present on C2 linkage group whereas three were present on D1b linkage group. Three major QTL were identified on LG C2 explaining phenotypic variation of 17, 12 and 27 per cent for YMD resistance. One minor QTL was also identified on LG D1b. For seed weight, one major QTL was identified on LG M with Sat_244 and Satt175 as flanking markers having an estimated 19.0 per cent phenotypic variance. Two minor QTLs were also identified on LG D1b.ennullThesis