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Dep. of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108
* Corresponding author (ehlke001{at}umn.edu)
‘HiPal’ cicer milkvetch (Astragalus cicer L.) (Reg. no. CV-202, PI 630975) was released by the Minnesota Agricultural Experiment Station on 1 February 2001. Cicer milkvetch performs well in the North Central region of the USA and Canada. It has many desirable agronomic traits including a rhizomatous growth habit and is bloat-safe, making it exceptionally well adapted to grazing. In addition, cicer milkvetch is extremely winter hardy, persistent, and is highly tolerant of insect pests common on forage legumes (Marten et al., 1987). However, in Minnesota, heifers (Bos sp.) grazing pure stands of cicer milkvetch had reduced intake and gains compared with heifers grazing pure stands of alfalfa (Medicago sativa L.) or birdsfoot trefoil (Lotus corniculatus L.) suggesting poor palatability (Marten et al., 1987).
HiPal is a 16-clone synthetic selected for improved palatability by grazing sheep (Ovis ssp.). The 16 clones trace to an evaluation for palatability of the world collection of cicer milkvetch which was supplied by C.E. Townsend, USDA-ARS in 1988. The germplasm consisted of 59 plant introductions primarily from Europe and Russia where cicer milkvetch is native; polycross progeny from seven of the parental clones of ‘Monarch’ used in a previous grazing trial (Townsend, 1986); open-pollinated seed collected from an old Soil Conservation Service planting at Mandan, ND; and the germplasm C-10 (Townsend, 1987) for a total of 68 entries.
In March 1988, the 68 germplasm sources were planted in the greenhouse in 164-cm3 plastic cones and transplanted into spaced-planted pastures for grazing by sheep (Ovis spp.) at St. Paul, MN in May, 1988 on 1-m centers. The experimental design was a randomized complete block with eight replications, each replicate consisted of six plants per entry for a total of 3264 plants. Appropriate chemical and mechanical weed control practices were employed to keep the pastures free of weeds. The relative palatability (selection when a choice was offered) of the space plants was determined by four mature ewe sheep in June and August 1989 and June and September 1990. Plants were grazed when they were vegetative and about 20 cm tall. Relative palatability was estimated by two trained observers using a 1 (completely consumed) to 10 (completely rejected) scale. Final scores were assigned when the most palatable plants had ratings of 1 or 2. Before grazing, individual plants were scored for vigor on a scale from 1 to 10, where 10 was the most vigorous. Once the grazing period began, plants were rated daily for percent consumption.
Two plants per replicate were selected based on vigorous growth scores and greater than 50% of the biomass consumed during all four grazing periods. The 16 parental clones selected for HiPal averaged 61% consumption by grazing sheep, scored 7.1 for vigor, and traced to nine plant introductions (PI 362233, 362236, 362272, 362249, 362251, 362257, 362259, 362267, and 362269) and three polycross families from the parental clones of Monarch (F3-C3, 16-5 III-C7, and 17-3 I C8). The 16 selected parental clones were vegetatively propagated and transplanted to an isolated crossing block at Rosemount and Roseau, MN. Syn1 seed was produced by compositing equal seed quantities from each of the 16 clones. Syn2 was produced by transplanting approximately 200 plants from syn1 seed into an isolated crossing block at Rosemount, MN, and bulking the seed from the individual plants.
HiPal was evaluated for improved palatability in a small plot grazing trial established in 1993 at St. Paul, MN. The experimental design was a randomized complete block with six replicates and plot size was 1.8 x 3.0 m. Entries in the trial consisted of HiPal, Monarch, ‘Lutana’, and four additional experimental populations. The relative palatability of the entries was evaluated by five or six grazing lambs in September 1993, June 1994, and June and August 1995, when cicer milkvetch was at a late vegetative stage. Palatability was estimated daily by evaluating percent consumption as in the original germplasm evaluation. The final palatability score for each plot was assigned when the herbage of several plots had been well consumed (30% or less of the original total forage remaining as residue). Forage yield and quality samples were collected before grazing and analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude protein (CP).
Palatability differences between HiPal, Monarch, and Lutana occurred at two of the four grazing periods. In June, 1995, the sheep consumed 25% more of the HiPal forage early in the grazing period and over 50% more of the HiPal forage from 6 to 9 d after being placed on the pasture when compared with Lutana and Monarch. Differences in palatability were also detected during August 1995 with similar results with 21 to 56% more HiPal consumed than Monarch or Lutana. One cycle of selection for improved palatability in cicer milkvetch was successful in producing HiPal, which averaged 19% of the forage biomass remaining at the end of the four grazing periods compared with 29 and 34% for the forage remaining for Monarch and Lutana.
HiPal had similar NDF (305.9 g kg-1) and ADF (272.6 g kg-1) concentrations and higher CP (214.1 vs. 199.8 g kg-1 CP) than Monarch and Lutana at three of the four grazings. The entries had similar final stand densities (74%), vigor ratings (6.3; rated on a scale of 1 to 10 = most vigorous), height (58 cm), and dry matter yield (3405 kg ha-1).
Breeder seed will be maintained by the Minnesota Agricultural Experiment Station, St. Paul, MN. An exclusive release of the HiPal marketing rights has been granted to Norfarm Seeds, Inc., Roseau, MN. The following generations will be allowed: Foundation seed may be produced for three consecutive years; there will be no Registered seed class; Certified seed may be produced for five consecutive years. All seed of HiPal will be sold as a Certified seed class. U.S. Plant Variety Protection for HiPal will not be sought
NOTES
Contribution from the Minnesota Agric. Exp. Stn. Registration by CSSA.
Accepted for publication August 31, 2002.
REFERENCES
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