West Salem, WI, United States
West Salem, WI, United States

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Steppuhn H.,Agriculture and Agri Food Canada | Iwaasa A.D.,Agriculture and Agri Food Canada | Holzer J.,Montana Dryland Salinity Control Association | Johnson D.W.,Cal West Seeds | Ulmer M.,U.S. Department of Agriculture
American Society of Agricultural and Biological Engineers Annual International Meeting 2012, ASABE 2012 | Year: 2012

Recommendations for controlling root-zone salinity in dryland agriculture include: (1) growing alfalfa in ground water recharge areas; (2) lowering near-surface, saline water-tables by utilizing phreatic waters with deep-rooted alfalfa, and (3) one-time flushing of saline seedbeds prior to seeding alfalfa. Alfalfa serves as an important element in all three strategies. Recent developments in breeding dormant-type alfalfa populations have resulted in eight candidate cultivars with greater salinity tolerance. After an initial screening, two were further evaluated and compared to Rangelander alfalfa, known for its tolerance by hay producers in the northern Great Plains and Canadian Prairies. The Salinity Tolerance Indices (STI) of Bridgeview and Halo (PGI 427) equaled 7.77 and 8.27, respectively, and exceeded the STI of Rangelander (6.79) by 15 and 22%. Dryland salinity rarely exists uniformly across a field; salts typically accumulate in varying concentrations within small-to-medium patches scattered among the more negligibly saline areas and comprise less than 50% of the total area. The total alfalfa yield from such mixed fields depends on the cultivar's inherent ability to produce forage in both saline and non-saline root zones. The value of increased salinity tolerance in an alfalfa cultivar depends on the specific agronomic-hydrologic practice used to control root-zone salinization. The more frequent and the closer the contact of the alfalfa roots with the saline soil, the greater the merits of the cultivar's salinity tolerance. Identification of the salinity tolerance of the alfalfa used in the salinity control forms an essential part of selecting the most appropriate remedial agronomic-hydrologic practice.

Steppuhn H.,Agriculture and Agri Food Canada | Acharya S.N.,Agriculture and Agri Food Canada | Iwaasa A.D.,Agriculture and Agri Food Canada | Gruber M.,Agriculture and Agri Food Canada | Miller D.R.,Cal West Seeds
Canadian Journal of Plant Science | Year: 2012

Alfalfa productivity can be enhanced by growing crops from cultivars tolerant of root-zone salinity. Rangelander, Keho, Bridgeview, Halo, CW054038, CW064027, Rugged, Bullseye and TS4002 alfalfa plants (respectively designated Ra, Ke, Br, Ha, C8, C7, Ru, Bu and T4) were grown in sand tanks irrigated with nutrient-sulphate solutions averaging 1.53 (nutrients only), 8.03 and 15.61 dS m-1 in electrical conductivity. Except for Br and C7, seedlings emerged equally under the 1.5 and 8.0 dS m-1 treatments, but decreased in the 15.6 dS m-1 treatment by percentages ranging from 3.1 through 29.5. Average shoot biomass among the populations respectively decreased by 49.6, 43.6 and 37.6% in the 1st, 1st+2nd, and 1st+2nd+3rd harvest-cuts as salinity increased from 1.5 to 8.0 dS m-1 and by 80.1, 73.2 and 67.1% from 1.5 to 15.6 dS m-1. At 1.5 dS m-1, the C7 plants consistently produced more shoot biomass than the T4, Bu, Ha, Ru, Ra, or Ke plants. At 8 dS m-1, the relative yields of the Ha plants (scaled by their 1.5 dS m-1 production) exceeded those from the other populations, although the Ha plants produced no greater actual shoot biomass than the C7 or the C8 plants.

Riday H.,U.S. Department of Agriculture | Johnson D.W.,Cal West Seeds | Heyduk K.,University of Georgia | Raasch J.A.,U.S. Department of Agriculture | And 2 more authors.
Euphytica | Year: 2013

Determining unknown parentage in autotetraploid alfalfa (Medicago sativa L.) (2n = 4x = 32) can improve breeding gains. An exclusion analysis-based paternity testing SAS code, amenable to genotyping errors, is presented for autotetraploid species utilizing co-dominant molecular markers with ambiguous dosage. To demonstrate the paternity testing SAS code, 19 SSR loci were genotyped and analyzed on 1,107 progeny from a commercial, isolated, clonally replicated, 16-parent alfalfa breeding polycross which was pollinated by leafcutter bees (Megachile rotundata F.). Paternal assignment success rate was over 90 %. Among typed progeny, 45 % were the result of self-fertilization. Significant differences were detected between the 15 parents that produced seed and were observed as fathers for (1) total fertilizing pollen contribution (% deviation from expectation), (2) self-fertilization rates (%), and (3) outcrossing fertilizing pollen contribution (% deviation from expectation). Physical within-cage distance between parental plants was correlated with outcrossing fertilizing pollen frequency (negative power function). Parental seed yield was positively correlated with total fertilizing pollen contribution, particularly with self-fertilization rates (42 % self-fertilization and 17 % outcrossing). These correlations suggest that selecting for increased seed yield may result in indirect selection for increased self-fertilization rates. Parental total fertilizing pollen contribution was 62 % determined by outcrossing and 35 % by self-fertilization. This study cautions alfalfa breeders that heretofore unconsidered sources of inbreeding could be present in some breeding materials. This study also provides cost effective and easy to use molecular genetic tools for detecting, managing, and/or selecting against (through breeding) those sources of inbreeding. © 2013 Springer Science+Business Media Dordrecht (outside the USA).

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