Selection and Evaluation of Low Phytate/Low Stachyose Soybean Genotypes in Arkansas.

Soybean seed stachyose and phytic acid are not digested by monogastric animals, and thus represent an obstacle for an efficient utilization of soybean meal in animal feed. Further, land fertilization with animal manure high in phosphorous can result in eutrophication of surface and ground water. The objectives of this research were to identify breeding lines with high sucrose, low stachyose, low phytate and satisfactory yield potential from a population of 123 F_2:6 lines derived from the cross of a high sucrose, low stachyose, low phytate genotype and a normal sugar and phytate, mid-oleic genotype. In 2009, the lines were grown in a RCBD with two replications in two Arkansas locations. Sugar and inorganic phosphorus (indirect measure of phytate) concentration were determined in a seed sample of each plot. Based on phenotypic data, a subset of 40 high inorganic phosphorous and/or low stachyose lines were selected and evaluated in a RCBD with two replications in two Arkansas locations in 2010. Yield, sugar, protein, oil, and fatty acid concentration were measured in the 40 lines. Sugar and inorganic phosphorous were stable in selected lines over years and locations. No line exhibited higher oleic acid concentration than the mid-oleic parent (47%). The average yield ranged from 10 bu/ac  to 44.3 bu/ac. Four lines showed no significant yield differences with the average (44.1 bu/ac) of commercial checks (5002T, 5601T, UA 4910). Future research includes crossing these lines to high yield cultivars to develop progenies with better yield potential and wider adaptation to Arkansas environments.