Planting Date and Irrigation Effects on Seed Quality of Early-Maturing Soybean in the Mid-South USA.

Information is lacking in soybean [Glycine max (L) Merr.] on whether or not variety selection and management practices can improve seed quality in early production systems. Effects of planting date, irrigation, genotype and maturity on seed quality traits in soybean were investigated in Arkansas for two years. Irrigation (I), planting dates (PD), and maturity groups/genotypes (MG/G) significantly affected seed quality traits. The MG/G, followed by I and PD treatments, made the largest contribution to variations in seed quality traits. Irrigation and late planting significantly improved seed standard and cold germination for most maturity groups. Irrigation also tended to increase seed protein content, whereas planting dates had no impact on seed protein and oil content. Both irrigation and planting dates had little or no effect on visual seed quality and seed pathogen infection. Maturity group and genotype significantly affected all seed quality traits. Late-maturing genotypes exhibited significantly higher standard and cold germination rate, fewer pathogen-infected seed, and better visual seed quality than early-maturing genotypes. Wide-row spacing improved seed germination. Seed germination and vigor of early-maturing genotypes decreased, whereas those of late-maturity genotypes improved when planting was delayed from April to June. Early-maturing genotypes were more responsive to irrigation when planted late. Significant correlation was found between cold and standard germination with other seed quality traits, including visual seed quality rating, disease-free seeds, and Phomopsis-infected seeds. We demonstrated that variety selection and irrigation were important in achieving high seed quality of early-maturing soybeans. [ABSTRACT FROM AUTHOR]