Yield is a multi-factorial trait determined by several genetic traits and highly correlated with important agronomic traits in many crops including soybean. [Glycine max (L.)]. Plant height, seed and pod numbers, and seed weight are all components of yield and polygenic in nature. The objective of this study was to identify quantitative trait loci (QTL) for days to germination, days to flowering, plant height, pod number, seed number, 100-seed weight, and total seed weight in soybean using the using the PI 438489B by 'Hamilton' recombinant inbred line (RIL) population (PIxH, n=50). A total of 18 QTL were found on 10 different chromosomes. Three QTL for days to germination (qDG001-qDG003) have been identified on chromosomes 5b, 6, and 13b. Two QTL (qDF001 and qDF002) have been identified on chromosomes 9 and 13b, respectively. On QTL for plant height (qPH001) have been identified on chromosome 6. Four QTL for pod number (qPN001-qPN004) had been identified on chromosomes 2, 6, and 8 (2 QTL), respectively. Two QTL for seed number (qSN001 and qSN002) have been identified on chromosomes 5b and 11b, respectively. Five QTL for 100-seed weight (qSW001 to qSW005) have been identified on chromosomes 5a, 6, 8, 9, and 11c, respectively. Two QTL for total seed weight (qTSW001 and qTSW002) have been identified on chromosomes 5b and 17c, respectively. The QTL identified here may be introduced in breeding programs to develop soybean cultivars with high yield potential.

Clark, W. D., Reyes-Valdes, M. H., Bond, J. and Kantartzi, S. K. 2013. Performance of LS97-1610בSpencer’ soybean recombinant inbred line population segregating for resistance to Fusarium virguliforme . Can. J. Plant Sci. 93: 1179–1185. Sudden death syndrome (SDS) is a devastating disease in soybean which is caused by Fusarium virguliforme. Sudden death syndrome resistance is a quantitative trait; therefore, development of resistant varieties requires understanding of complex genetics and environmental effect. In this study, we aimed to characterize 94 F5:8 recombinant inbred (RI) lines derived from a cross between a resistant line for SDS, LS97-1610 and a susceptible cultivar, ‘Spencer’ and to identify sources of resistance. The RI lines were evaluated for their relative resistance (RR) to SDS along with the parents in four different environments; two years (2009 and 2010) and two locations (Carbondale and Valmeyer, IL). Analysis of variance revealed significant interactions between genotype and environment in each year of experimentation and in 2-yr combined data. Broad-sense heritability was estimated by ANOVA results, and it was moderate (61%). These results indicate that SDS resistance is partially unpredictable due to environmental influence. Ten RI were identified to have a RR with no significant differences from LS97-1610 and two of them had a RR lower than resistant parent. These stable RI across environments were used for further evaluation in breeding programs. Additionally, data obtained from field evaluation can be used in combination with molecular data to study the effect of quantitative trait loci (QTL) with the environment. The identification of common QTL across environments with consistent expression is the ultimate goal of every marker-assisted selection program.

The objective of this study was to evaluate a recombinant inbred line population derived from a cross between a recombinant inbred line (RIL) resistant to sudden death syndrome (SDS). 'LS90-1920' with a susceptible line, 'Spencer' in order to identify any significant association between yield and important agronomic traits with SDS, estimate heritability of these traits and determine whether there are traits that can be used as predictors for SDS resistance. Correlation coefficients for yield and agronomic traits (maturity, lodging, and plant height) were moderately to highly significant but there was no significant association between these traits and SDS resistance. Genotype by environment interaction was significant for all traits studied except of plant height. Maturity, lodging, plant height and SDS resistance were moderately to highly heritable whereas yield showed very low heritability. Our findings showed that environment plays a very crucial role in selection. It is showed that genotypic selection can speed up but cannot replace phenotypic selection across environments and time. Environment is important for the development and production of crop plants because it optimizes the association between the genotype and the phenotype. Highlights: Created Recombinant Inbred Line; Tested for agronomic traits including yield; Tested for disease resistance; Analyzed results to determine if Recombinant Inbred Line differed from the parental lines; Determined if traits were inherited from parents.