Title: In search of genetic resources for improvement of seedling vigor under cold temperatures Authors
Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: June 1, 2011
Publication Date: June 15, 2011
Citation: McClung, A.M., Duke, S.E., Yan, W., Yan, Z., Gibbons, J., Stivers, A. 2011. In search of genetic resources for improvement of seedling vigor under cold temperatures. Texas Rice Special Section, Highlighting Research in 2011. p. V. Technical Abstract: Rice production practices are constantly being modified as a result of the availability of new technologies and the changing economic picture. Farmers are planting rice at least one month earlier than a decade ago. With increasing interest in alternative cropping systems, minimum tillage, and water conservation, there is a need to develop rice varieties that have improved seed germination and vigor under the cold temperatures that can exist during early spring plantings. Such varieties will have improved stand establishment and will better compete with weeds at a time when herbicides are not as effective. In addition, varieties that have good stand establishment under cold temperatures can be planted and harvested earlier in the season, thus reducing irrigation demands during late summer. The objectives of this study were to survey a large diverse set of rice varieties from around the world to identify accessions with improved seedling vigor under cold temperatures that can be used by breeders for varietal improvement. We screened about 2,600 rice accessions, including 1,685 varieties in the USDA "Core" collection, 823 accessions from cold (temperate) regions, and over 100 breeding lines and parents. Each accession was evaluated for germination in growth chambers using three replicates of 30 seed at 54 deg F and two replicates at 79 deg F. Each seedlot was cleaned, sterilized with 10% Chlorox, placed on paper towels that were uniformly moistened and sealed prior to being placed into the growth chamber. Percent germination was determined approximately 7 days after initiation for the warm treatment and following 30 days of the cold treatment. The accessions were compared to Quilla 66304 (PI 560281), a cold-tolerant variety from Central America (70% germination at 54 deg F), Lemont (48% germination), and Zhe 733, a tropical variety from China, (40% germination). Results identified 590 varieties (23% of the accessions) that were equal to or better than Quilla 66304 for cold germination. Accession 89-5 (PI 614993) originating from Sichuan, China, had plant and grain quality traits comparable to southern US long grains, along with 79% germination under cold temperatures. Within the Core and Temperate groups, 31 varieties were identified that had >90% germination at 54 deg F. Interestingly, these originated from countries in both tropical and temperate climates. This study demonstrates that genetic resources from around the world can be used to improve seedling vigor under cold temperatures.