Soybean [Glycine max (L.) Merr.] yield is responsive to changes in plant population and row spacing. The objective of this study was to compare some agronomic traits of soybean cultivated in two different row spaces in a field in St Pauls, NC. Among the traits, total seed weight showed the highest level of variation than others in both 25 cm (97.31%) and 50cm (60.23%) row space. The lowest co-efficient of variation, 5.06% at 25 cm and 11.54% at 50 cm were found for days to flowering. Mean value showed that plants grown in 25 cm row space have a higher 100-seed and total seed weight than those grown in 50 cm row space. Plants grown in 50 cm row space had a slightly increased mean plant height compared to those grown on 25 cm. Plants grown in 50 cm row space had greater pod and seed numbers compared to those grown on 25 cm. Comparisons of the agronomic parameters between 25 and 50 cm row space employed by two-tailed t test (type 2; α = 0.05) showed that there are significant differences in days to germination, days to flowering, number of seeds, and total seed weight between plants grown in 25 cm vs. 50 cm row space; while plant height and number of pods were not differ significantly. However, further research may reveal a system for soybeans cultivation in the future which would increase the probability of obtaining maximum yields with narrow rows.

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.

The objectives of this study were to detect quantitative trait loci (QTL) for moisture, protein, and oil content in soybean grown in two plant density environments. Soybean recombinant inbred lines (RIL), obtained from a cross between cultivars PI 438489B and Hamilton, were used. Thirty one linkage groups were obtained from high density genetic linkage maps constructed by 1,536 Universal Soy Linkage Panel 1.0 of single nucleotide polymorphisms (SNP) markers. For the lines cultivated in higher plant density (25 cm row space), ten QTLs were mapped in A2, B2, C2, D1a, M and O linkage groups for moisture, protein, and oil. Two QTLs for moisture, two QTLs for protein and six QTLs for oil explained 0.09, 15.36 and 3.54% of the phenotypic variation of moisture, protein, and oil respectively. For the lines cultivated in lower density (50 cm row space), three QTLs for each of moisture and protein were mapped in linkage groups A2, C1, D1b, L and O; QTLs for moisture and protein explained 0.96 and 10.63% of the phenotypic variation respectively. These QTL will facilitate the implementation of MAS for moisture, protein and oil content in soybean-breeding programs.

Soybean [Glycine max (L.) Merr.] yield is responsive to changes in plant population and row spacing. The objective of this study was to compare some agronomic traits of soybean cultivated in two different row spaces in a field in St Pauls, NC. Among the traits, total seed weight showed the highest level of variation than others in both 25 cm (97.31%) and 50cm (60.23%) row space. The lowest co-efficient of variation, 5.06% at 25 cm and 11.54% at 50 cm were found for days to flowering. Mean value showed that plants grown in 25 cm row space have a higher 100-seed and total seed weight than those grown in 50 cm row space. Plants grown in 50 cm row space had a slightly increased mean plant height compared to those grown on 25 cm. Plants grown in 50 cm row space had greater pod and seed numbers compared to those grown on 25 cm. Comparisons of the agronomic parameters between 25 and 50 cm row space employed by two-tailed t test (type 2; α = 0.05) showed that there are significant differences in days to germination, days to flowering, number of seeds, and total seed weight between plants grown in 25 cm vs. 50 cm row space; while plant height and number of pods were not differ significantly. However, further research may reveal a system for soybeans cultivation in the future which would increase the probability of obtaining maximum yields with narrow rows.