Seed source effect on field emergence of soybean lines with reduced phytate and raffinose saccharides

Soybean [Glycine max (L.) Merr.] lines homozygous for the mips allele (mips lines) have reduced phytate P and raffinose saccharides in the protein meal. Less phytate is desirable for reducing the P content of manure from nonruminant animals and less raffinose saccharides increases the amount of metabolizable energy available to them. Field trials indicated that seedling emergence percentage of mips lines was less for seed produced in a subtropical environment than a temperate environment. The objective of this study was to determine if field emergence of mips lines is influenced by the environment used for seed production. Seed of six mips lines and four commercial cultivars (Mips lines) produced in four temperate and 12 subtropical environments during 2 yr was evaluated for Held emergence percentage, seed viability percentage, and germination percentage in warm germination, cold vigor, and accelerated aging tests. The field emergence percentage of mips lines was significantly less than Mips lines for all seed sources. The mips lines had a mean Held emergence of 63% for temperate sources and 8% for subtropical sources while Mips lines had a mean field emergence of 77% for temperate sources and 83% for subtropical sources. The mean seed viability percentage for the mips lines based on the tetrazolium test of 88% for temperate sources and 70% for subtropical sources accounted for only part of the differences in field emergence. Differences in field emergence between the mips and Mips lines were not consistently predicted by the warm germination and cold vigor tests for temperate sources. The accelerated aging test effectively differentiated the field emergence potential of the mips and Mips lines for all seed sources. Seed source should be a consideration when evaluating the field emergence of mips lines in a breeding program or for obtaining acceptable plant populations in commercial fields.