Molecular approaches to improve soybean plant architecture and seed composition
Abstract
Soybean is an important agronomic crop which has been widely used as a vegetable oil as well as a source of protein for animals and humans. Among various desired traits for genetic improvement to improve the value of soybean, yield and seed composition deserve attention considering its ever-increasing demand as well as where its overall value comes from. In terms of yield improvement, the current research suggested an alternative strategy to remodel the architecture of soybean plants for better adaptation, especially to high yield environments. From the field trials in three latitudinal environments in the US, tall determinate soybean types were found to change the overall plant architecture of soybean in both Midwest and Southern environments in the US by increasing plant height and node number and creating similar stem thickness and pod density at the stem tip compared to typical determinate types. The increase in pod-bearing nodes with lodging resistance has the potential to result in more yield, especially in high yield planting environments. Further agronomic merits need to be examined in diverse environments for its full utilization in soybean breeding. For the improvement of soybean seed composition, this research showed the feasibility of soybean variety development with an oil and meal value bundle. The results from eight environments indicated that the desired oil, the high oleic and low linolenic acid oil trait (HOLL; [greater than] 70 percent oleic and [less than] 3 percent linolenic acid), and meal value traits, the reduced seed content of the raffinose family of oligosaccharides (RFO), can be successfully combined by genotype selection without interference. The modified seed composition traits will contribute to creating healthier, more oxidatively stable soybean oil and higher metabolizable energy soybean meal.
Degree
Ph. D.