A Survey of the Agronomic and End Use Characteristics of Low Phytic Acid Soybeans
Phytic acid (PA) accounts for up to 75% of the P in soybean (Glycine max L. Merr.) seeds, but it is indigestible by mono- and agastric animals resulting in economic and environmental detriment. Soybean lines with genetically reduced PA contents have been developed using three distinct mutant alleles at the MIPS1, LPA1, and LPA2 genes resulting in up to a 75% reduction in PA. Low PA (LPA) soymeal-based feeds have been tested on several agricultural species and shown to reduce the P in the animal effluent, but they have not been tested on any aquacultural species. However, LPA soybean lines often exhibit low field emergence making them commercially inviable. The cause of this phenomenon is widely debated with possibilities ranging from increased disease pressure to decreased seedling vigor. The objectives of this research were to 1) enhance field emergence of LPA soybean varieties through pre-planting seed treatments, 2) study the impact of the LPA mutant alleles on agronomic, quality, and seed composition traits, and 3) design a low-error method for studying the effect of LPA soymeal-based feeds on aquatic animals using Pacific White Shrimp (Litoenaeus vannamei). These results describe a variety of agronomic and genetic strategies with which the low field emergence of LPA soybeans can be addressed, reveal a heretofore not reported interaction between the mips1 and lpa2 alleles to further increase the digestibility of soymeal, and a possible method for studying LPA soymeal based feed on aquacultural animals.