Seed source affects field emergence of low-phytate soybean lines

Seed production in subtropical environments is commonly used by soybean [Glycine max (L.) Merr.] breeders to reduce the number of years for cultivar development. Low-phytate (LP) soybean lines with the mips allele had substantially reduced field emergence when planted with seed from a subtropical source. The objective of this study was to determine if seed source also would impact the field emergence of low-phytate lines with the pha1 and pha2 alleles. Seed of six BC3F4-derived LP-lines, the LP donor parent CX1834-1-6 (CX1834), and the normal-phytate (NP) recurrent parent B01769B019 (121019), was harvested from the field at Ames, IA, in 2005 (IA-2005), at Ponce, PR, in January 2007 (PR-Jan), and at Ponce, PR, in May 2007 (PR-May). The three seed sources of the eight lines were evaluated at three Iowa locations in 2007. The mean field emergence of LP lines was 77.6% for the IA-2005 source, 70.1% for the PR-Jan source, and 25.4% for the PR-May source while that of B019 ranged from 80.3 to 82.0% for the three sources. The seed source used to plant lines with the pha1 and pha2 alleles can have a significant influence on their field emergence, which can impact the development and evaluation of LP lines and on seed increases for commercial production.