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Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/14/2018 Publication Date: 7/1/2018 Citation: Jones, T.A., Larson, S.R. 2018. Trait response and changes in genetic variation upon selection for spike number in salina wildrye. Rangeland Ecology and Management. 71(4):443-448. https://doi.org/10.1016/j.rama.2018.03.005. DOI: https://doi.org/10.1016/j.rama.2018.03.005 Interpretive Summary: Salina wildrye is a native perennial grass that is potentially useful for restoration of damaged rangelands. However, its poor seed production has precluded its ability to secure a place in the seed industry. We conducted two cycles of recurrent selection for increased spike number on the 9043501 population of salina wildrye, which resulted in increased spike number, seeds per spike, and seed yield per plant. However, plant dry-matter did not change. We detected some loss of genetic variation as a result of the selection using AFLP markers, indicating that this should be monitored with remedial action taken if necessary. Our results indicate that salina wildrye seed yield can be improved considerably, opening up the possibility that its seed may eventially become available for restoration. Considerable demand exists for seed of this species in the Colorado Plateau, a region drained by the Colorado River in Utah, Colorado, New Mexico, and Arizona. Technical Abstract: Salina wildrye (Leymus salinus {M.E. Jones} A. Love) is a perennial cool-season grass native to the Intermountain Region that could potentially become an important restoration species, particularly in the Colorado Plateau of eastern Utah, western Colorado, northern Arizona, and northwestern New Mexico. However, seed production of this species has never become commercially viable due to a paucity of inflorescences. For this reason, we have embarked on a program of recurrent selection to increase spike production in 90436501, an octoploid salina wildrye population originating in northeastern New Mexico. Two cycles of selection for increased spike number in the first seed-production year were preceded by two cycles of selection for salinity tolerance in this population. In a replicated test at Millville, Utah, selection increased spike number (P<0.05) by 4.3 spikes per plant (19.8%) per cycle of selection in the first seed-production year (2013), but no change was seen in 2014 or 2015 (P>0.0.10). Seeds per spike and individual seed mass did not change (P>0.10) with selection, thus no trade-off was seen between spike number and these two traits. As a result, seed yield increased (P<0.05) 0.32 g per plant per cycle (36.8%) in 2013, the first seed-production year, with no increase (P>0.10) seen the following two seed-production years. Selection increased canopy height (P<0.01) 3.9 cm per cycle (6.7%) in 2013 and dry-matter production (P<0.05) 2.6 g per plant per cycle (4.9%) in 2015, though no change was seen for this trait in 2012-2014. Selection also increased (P<0.05) germination 1.5% per cycle in 2014, but no change (P>0.10) was seen for germination percentage in 2013 or for germination rate in either year. Neutral AFLP DNA primers detected losses of genetic variation subsequent to two of the cycles of selection, presumably due to genetic drift as a consequence of an insufficient number of parents being recombined. We recommend genetic monitoring to quantify any loss of genetic variation that may accompany recurrent selection. If losses are detected, genetic variation may be augmented by introducing germplasm from individuals outside of the genetically compromised population, a practice we refer to as 'detect and correct.' |
