Genetic improvement of seedling emergence of soybean lines with low phytate

Seedling emergence of low-phytate (LP) soybean [Glycine max (L.) Merr.] lines has been reported to be lower than that of normal-phytate (NP) lines. One objective of this study was to evaluate if backcrossing the LP trait into a NP line would result in LP progeny with normal emergence. The LP line CX1834-1-6 (CX1834) was crossed to B01769BO19 (13019), a NP line with reduced palmitate content, and three backcrosses were made to B019. A total of 36 BC3F4-derived LP lines from the population were evaluated at five locations in 2005 in comparison with CX1834, 6019, and an NP cultivar IA3023. The mean phytate P and inorganic P content of all the backcross lines was not significantly different from CX1834. There were 18 backcross lines that had a mean field emergence that was significantly greater than CX1834 and not significantly different from B019. The results indicated that backcrossing seemed to be successful for developing LP lines with normal field emergence. A second objective of the study was to determine the effectiveness of warm germination, cold vigor, and accelerated aging tests for predicting field emergence of LP lines. Fifteen of the backcross lines were evaluated in the three tests that represented the range of field emergence that had been observed. The tests were useful for identifying lines with inferior field emergence but were not reliable enough to replace field tests for identifying the best emerging lines.