Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Soybean heterosis and response to water: Yield, yield components, and morphology
A possible method to identify populations that may be more likely to generate inbred lines higher in yield than either parent is an early generation test for heterosis in F1 hybrids and or F2 bulks. To determine if measuring heterosis could be used to genetically improve soybean response to water, we compared the yield performance of the hybrid with its inbred parents in six soybean matings. The F1 hybrids, F2 bulks, and seven inbred parents were evaluated in both limited and full irrigation in replicated short-row and standard yield trials from multiple environments in Nebraska and Chile. Midparent heterosis (MPH) was detected in F1 yield trials for all but one family under limited irrigation (range: +7% to +26%) and under full irrigation (+5% to +21%). High-parent heterosis (HPH) was also detected under limited irrigation (+8% and +21%) and full irrigation (+7% and +10%) for only two families. Of those two families, one showed F2 bulk yield MPH under both limited and full irrigation, indicating that F2 field trial evaluations are also a viable early generation screening procedure. The F1 and F2 seed yield was significantly correlated in both irrigation treatments. Environment (location-year) had an effect on heterosis, but heterosis did not differ between water treatments. There was an environment × family interaction for both MPH and HPH, indicating families differed in their expression of heterosis in different environments. Soybean breeders may consider conducting early-generation evaluation of heterosis to identify populations more worthy of generation advance because these are more likely to generate the best performing lines under sup-optimal and optimal conditions. An analysis of 30 yield and plant components indicated that an increased main stem seed number and seed mass contributed to yield heterosis under limited irrigation. Hybrids exhibited greater haulm production, main stem internode length, and accordingly, plant height. Under limited irrigation, hybrids exceeded the midparent mean relative to main stem nodes and branches. The main stem components were the most responsive to water compared to the branch components. These characteristics may help breeders decide which yield and plant components to focus on when practicing yield-improvement selection in soybean.
Ruff, Leah Anne, "Soybean heterosis and response to water: Yield, yield components, and morphology" (2016). ETD collection for University of Nebraska - Lincoln. AAI10143329.