Breeding for improved emergence of low-phytate soybean lines

Abstract

<p>Seed production in subtropical environments is commonly used by soybean [Glycine max (L.) Merr.] breeders to reduce the number of years required for cultivar development. One objective of this study was to determine if seed source would impact the field emergence of low-phytate (LP) 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 (B019), was harvested from the field at Ames, IA, in 2005 (IA), at Ponce, Puerto Rico, in January 2007 (PR-Jan), and at Ponce, 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 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.;A second objective of this study was to determine if the improved emergence of LP lines developed at Iowa State University would be inherited by their progeny when crossed with conventional NP cultivars to form single-cross populations or used as the donor parent of the LP trait to form backcross populations. Sixteen LP F3:5 single-cross lines, 33 LP BC1F 2:4 backcross lines, four LP parent lines, and six NP parent lines were evaluated for field emergence at three Iowa locations in 2007. The seed used to plant the test was harvested from the PR-May environment. The single-cross lines had a mean field emergence of 42.8% and a range of 6.9 to 69.8%, the backcross lines had a mean of 31.4% and a range of 5.5 to 55.5%, the LP parent lines had a mean of 44.9% with a range of 30.1-59.0%, and the NP parent lines had a mean of 71.4% and a range of 46.1-80.8%. The results indicated that the LP lines with improved field emergence did not convey the trait to all of their progeny when evaluated with seed form PR-May.</p>