Location: Crop Genetics Research Unit
2013 Annual Report
Tolerance to drought can be measured in terms of a soybean plant’s water use efficiency (WUE). Combining improved WUE with high-germinability under heat stress in a new soybean line would be very desirable. Toward that end, 766 F2 plants from 6 independent populations of PI 567201D x 04025-1-1-1-4 were grown in 2012. From the total of 766 plants, 57 agronomically improved plants were selected and harvested. Seeds from these 57 plants were sent for standard germination tests. Based on these germination tests, nine F2:3 families were selected for testing for WUE. The nine families were planted in Stoneville, MS, April 29, 2013. Each emerged plant was tagged for later tissue sampling for WUE in 2013. Leaf tissues from 2012 of these nine lines and the parents are currently being ground and prepared for shipping to the University of California, Davis Stable Isotope Facility. Lines with the best WUE scores will be selected prior to tissue sampling in 2013 so that only individual plants from selected F2:3 families will be tissue sampled in 2013. This process will be repeated over the next three to four years to create a new pure line soybean with high WUE and high germinability.
Additional breeding populations have been developed to combine WUE with high germinability. The following F2 seeds arrived from Puerto Rico and were planted in Stoneville, MS, May 30, 2013: PI 567201D x 04025-1-1-4-1-1 (Two populations of 160 seeds each) 04025-1-1-4-1-1 x PI 567201D (One population of 320 seeds) PI 398965 x 04025-1-1-4-1-1 (Five populations of 80 seeds each) 04025-1-1-4-1-1 x PI 398965 (Four populations of 80 seeds each)
The ability of soybeans to fix nitrogen during drought stress is also important for high seed yield. Hence, the following populations were developed to combine high germinability and high nitrogen fixation: PI 574483 x 04025-1-1-4-1-1 (Four populations of 80 seeds each) PI 442012A x 04025-1-1-4-1-1 (Three populations of 80 seeds each)
Finally, total plant nitrogen is associated with plant productivity. Therefore, the following populations were created to combine high nitrogen concentration with high germinability: PI 567572B x 04025-1-1-4-1-1 (Four populations of 80 seeds each) PI 417107 x 04025-1-1-4-1-1 (Three populations of 160 seeds each)
These breeding populations will be selected first for improved plant type and then high germinability. Selected families with high germinability will then be assayed for WUE, nitrogen fixation, and nitrogen concentration as appropriate.