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Poa is a complex genus taxonomically and genetically. As a result, relatively little information exists for this economically important genus with regards to reproductive mode and variability in chromosome number. We examined apomixis frequency and ploidy levels in 83 Poa accessions representing 33 species from the National Plant Germplasm System using flow cytometric techniques. In reproductive mode analysis, we analyzed at least three preparations of 50 seeds each from the accessions. In ploidy level analysis, at least three plants of each accession were analyzed. Sixty percent of the species had at least one apomictic or facultative apomictic accession; 40% were sexual. Thirty-three percent of the species had no sexual accessions. Autonomous apomixis was newly identified in P. bactriana and P. bulbosa in addition to it being previously reported in P. nervosa. Poa annua and P. trivialis were identified as obligate sexual, and P. nervosa as obligate apomictic. Two of four P. palustris accessions exhibited facultative apomixis. Ploidy levels among sexually reproducing Poa accessions ranged from 2n = 2x = 14 to 2n = 12x = 84, with most accessions between 2n = 3x = 21 to 2n = 8x = 56. Among apomictic accessions, ploidy levels ranged from 2n = 3x = 21 to 2n = 10x = 70, with most between 2n = 4x = 28 and 2n = 10x = 70. These results emphasize the wide variability in Poa, both among and within species.

Small burnet (Sanguisorba minor Scop.) is an evergreen forb readily utilized by livestock and wildlife that lacks persistence under heavy grazing. Our objective was to characterize all available National Plant Germplasm System (NPGS) small burnet germplasm for ploidy level and agronomic characteristics before initiating a breeding program. Ploidy level was determined by flow cytometry. Forage yield, flowering date, mortality, growth habit, and leafiness were determined at two locations in Utah. Of the materials tested 68% were tetraploids (2n = 4x = 28) and 32% octaploids (2n = 8x = 56). Significant variation was observed for all traits. Mean forage yield of the small burnet was 1.45 Mg [ha.sup.-1], ranging from not measurable to 2.96 Mg [ha.sup.-1] compared to Ladak alfalfa (Medicago sativa L.) at 2.28 mg [ha.sup.-1]. Flowering date varied among accessions by 12 d while mortality ranged from 0 to 100%. Variation was displayed in growth habit, including prostrate and upright forms, and leafiness. The range among accessions was similar within the two ploidy levels for all traits except flowering date which was 2 d earlier in the octaploids. It was shown that tetraploids and octaploids are present in roughly a 2:1 ratio in the NPGS small burnet germplasm. The forage production of some small burnet accessions can be comparable to alfalfa, and phenotypic variation is such that the germplasm has potential for improvement through recurrent selection.

The validity of spaced-plant evaluation to determine sward performance of forage grasses has been questioned. This experiment studied the efficiency of spaced-plant evaluation to indirectly improve sward yield and nutritional quality in tall fescue (Festuca arundinacea Schreb.). Narrowsense heritabilities, genetic and rank correlations, and indirect selection efficiencies were estimated for a tall fescue population grown in spaced plant and seeded sward environments. Heritability for yield was similar between spaced plants and swards (0.43 and 0.44, respectively), but genetic correlation between the two was low (0.37 [+ or -] 0.38). Inconsistency (r = 0.30, P = 0.17) in family ranking further suggested that spaced plants were not predictive of sward yield. Heritability of crude protein from swards was low (0.27 [+ or -] 0.25) compared with 0.77 [+ or -] 0.08 from spaced plants, but there was no genetic relationship between the two (r = -0.13 [+ or -] 0.30). Moderate to high heritabilities and genetic correlations were observed for most fiber traits, but indirect selection efficiencies and rank correlations of

Hedysarum boreale Nutt. is a perennial legume native to western North America, with robust foliage in the late spring season. Due to its wide native range, forage value, and [N.sub.2] fixation, H. boreale is of interest for rangeland revegetation and production. Seed cost is a major obstacle for utilization of H. boreale, primarily due to seed shattering and unreliable seed production, such that a need for improved germplasm exists. This study characterized the genetic relationships of H. boreale accessions, so plant breeders and geneticists will have the information necessary to maintain a broad genetic base within selected germplasm populations. Amplified fragment length polymorphism markers were used on 17 available accessions from Utah, Idaho, Colorado, and Alaska. Seventy percent of the total genetic variation was found within all 17 accessions, yet each accession showed significant isolation by distance. Genetic diversity within accessions was greatest in sites located in eastern Utah. The sole cultivar, Timp, had slightly greater genetic diversity than a collection made from the same site approximately 20 yr later. Two groups of metapopulations were identified in Utah, separated longitudinally approximately along the Wasatch mountain range.

Meadow bromegrass (Bromus riparius Rehm.) has gained interest as a highly productive pasture grass that can be used under management intensive grazing with limited irrigation. In 1999, 28 cloned parents and half-sib families of meadow bromegrass were each planted in a randomized complete block design to evaluate genetic variation of meadow bromegrass for dry matter yield (DMY) (Harvests 1 to 6), forage quality under repeated defoliation (Harvests 1, 3, and 5), and investigate intercharacter correlations. Narrow-sense heritability estimates and their standard errors for DMY at Harvests 2, 3, and 4 were 0.89 [+ or -] 0.32, 0.59 [+ or -] 0.28, and 0.53 [+ or -] 0.29, respectively. However, at Harvest 1 and 5, standard errors of the heritability estimates for DMY were equal to or greater than the estimates. All heritability estimates for crude protein (CP) were at least twice their standard errors at Harvests 1, 3, and 5. High narrow-sense heritabilities at Harvest 5 for acid detergent fiber (ADF) suggest that selection on forage harvested later in the growing season might be more efficient than forage harvested earlier in the season. Combined across years and within harvests, narrow-sense heritability estimates and standard errors for neutral detergent fiber (NDF) were 0.66 [+ or -] 0.29, 0.47 [+ or -] 0.30, and 0.71 [+ or -] 0.28, respectively. Based on correlations, it seems reasonable to assume that when selecting for increased DMY that ADF and NDF will increase and that CP and IVTD will decrease in this population.

Difficulties associated with producing high quality forage on salt affected soils is often associated with the inability of plants to establish and persist at elevated soil salinity levels. The cultivar NewHy RS-wheatgrass is recommended for use on range sites with moderate salinity problems that receive at least 35 cm of annual precipitation. Objectives of this study were to evaluate (i) the ability to improve plant persistence in NewHy over three cycles of greenhouse selection at increased salinity levels and (ii) corresponding changes in seedling vigor and germination under nonsaline conditions. Greenhouse grown plants were irrigated every 3 d with a complete nutrient solution and salt levels were increased by an electrical conductivity (EC) of 6 dS [m.sup.-1] every 1 to 2 wk until an EC level of 42 dS [m.sup.-1] was reached and maintained until plant mortality occurred in 2002 and 2003. Probit analysis was used to estimate the time and salt concentration required to kill 50% of the plants (L[D.sub.50]) in each cycle. Significant differences for L[D.sub.50] were found among the different cycles of NewHy selected for persistence under saline conditions and the quaekgrass [Elytrigia repens (L.) Nevski] parent with a resulting ranking of Cycle-3 > Cycle-2 > Cycle-1 > quackgrass > NewHy (Cycle-0). The largest single gain was achieved from NewHy Cycle-0 to Cycle-1, which required an additional 145 ECdays to reach an L[D.sub.50] level. Smaller increases were observed between Cydes-1 and -2 and between Cycles-2 and -3. Selection for persistence under a saline environment did not reduce seedling germination rate or vigor., EXCESS SOIL SALINITY is a major factor limiting the establishment, persistence, and productivity of forage grasses in the Intermountain West. The expanding population and accompanying demand for food, fiber, and [...]

A lack of salt-tolerant cultivars may be due in part to inadequate evaluation protocols used for selection. Our objective was to develop a greenhouse protocol that is simple and consistently separates genotypes for their relative ability to survive under saline conditions. In 2000 and 2001, 12 alfalfa (Medicago sativa L.) cultivars were seeded in 3.8- by 21-cm cone-shaped containers plugged with capillary matting and filled with silica sand. Six-week-old seedlings were submersed in a NaCl-nutrient solution starting at an electrical conductivity (EC) of 3.0 dS [m.sup.-1] and increased 3.0 dS [m.sup.-1] every 1 to 2 wk for 10 to 13 wk. Probit analysis was used to estimate the time and salt dose to reach 50 (L[D.sub.50]) and 75% (L[D.sub.75]) mortality. Probit results were compared with cultivar ranking for mean percentage plant mortality when overall trial mortality reached approximately 50 and 75%. Pearson's rank correlations between 2000 and 2001 at the L[D.sub.50] and L[D.sub.75] levels were r = 0.90 (P < 0.001) and r = 0.88 (P < 0.001), respectively. Rank correlations between 2000 and 2001 based on means when overall trial mortality levels were approximately 50 and 75% were r = 0.92 (P < 0.001) and r = 0.85 (P < 0.001), respectively. The correlations between mean percentage cultivar mortality rankings and the probit-based rankings were above r = 0.90 (P < 0.001) in both years. The high correlations verify that this protocol produces repeatable results and provides a method to effectively screen large numbers of plants for survival under saline conditions., IN SEMIARID REGIONS, limited water and hot dry climates frequently cause salinity concentrations that limit or prevent crop production. At low concentrations salt suppresses plant growth, and at higher concentrations [...]

Limited water and curtailed use of public lands for grazing has increased interest in intensively managed pastures in the western USA. Our objective was to evaluate forage production of sainfoin (Onobrychis viciifolia Scop.), a nonbloating legume, compared with alfalfa (Medicago sativa L.). Thirteen sainfoin cultivars and 'Deseret' alfalfa were evaluated at four water levels (WLs) and four harvests in 1998 and 1999 under a line-source irrigation system. Water levels (WL1, WL2, WL3, and WL4) received an average of 78.3, 65.8, 34.9, and 8.3 cm of water, respectively. Significant effects were found for cultivar, cultivar x WL, harvest date, and cultivar x harvest date. Annual production of sainfoin at WL1, WL2, WL3, and WL4 was 11.6, 11.4, 9.6, and 8.9 Mg ha (-1), respectively, whereas annual production of Deseret was 20.7, 18.5, 18.0, and 16.3 Mg ha (-1), respectively. Overall yield trends across WLs were linear for sainfoin and Deseret and were parallel (P = 0.55) with slopes of b = 0.042 and b = 0.054, respectively. Yield of sainfoin at Harvest 1 through 4 was 5.5, 2.1, 1.5, and 1.3 Mg [ha.sup.-1], respectively. Yield of Deseret from Harvest 1 through 4 was 5.9, 5.3, 4.7, and 2.4 Mg [ha.sup.-1], respectively. Yields of the two species at Harvest 1 did not differ. The flat linear trend across WLs verifies that both crops are tolerant to dry conditions. With its highest production potential during early growth, sainfoin is best suited for situations where early growth of a nonbloating legume is desired, but will not compete with alfalfa in total seasonal production., LOW PRECIPITATION and growing urbanization are placing increased demands on limited water supplies in the Intermountian Region of the western USA. This, coupled with federal land policies that curtail the [...]

Callose, a Β-1,3-glucan, is synthesized and deposited in the walls of megaspore mother cells (MMCs) of angiosperms that produce either normal monosporic ([is greater than] 90% of all angiosperm species) or bisporic embryo sacs. Such deposits are absent in angiosperms that produce tetrasporic embryo sacs and were recently shown to be absent in diplosporous Elymus rectisetus (Nees in Lehm.) A. Love & Connor, Tripsacum L. spp., and Poa nemoralis L. We determined the extent of callose deposits in MMCs of diplosporous weeping lovegrass (Eragrostis curvula Schrad.), several additional diplosporous Tripsacum accessions and aposporous buffelgrass (Pennisetum ciliare (L.) Link), Kentucky bluegrass (Poa pratensis L.), and Pennisetum squamulatum Fresen. Callose deposition was studied in pistils cleared in an aqueous aniline blue clearing medium and observed by means of UV microscopy. Pistils cleared with conventional clearing media were studied by means of interference contrast microscopy. Some pistils were cleared and analyzed in one clearing medium and recleared and reanalyzed in the other. A callosic MMC was observed in only one of 376 appropriately staged pistils taken from diplosporous species. This pistil, one of 89 weeping lovegrass pistils studied, was probably facultatively sexual. An absence of callose during megasporogenesis may be characteristic of most types of diplospory. Though present, the distributions and quantities of callose observed in MMC walls of aposporous apomicts were erratically reduced, possibly as a result of early NMC abortion or early activation of nucellar initials. Callose deficiencies and vacuolization patterns support the following hypotheses: (i) apospory is caused by a moderately precocious gametophytization of nucellar cells, and (ii) bispory, tetraspory, and diplospory are caused by a moderately to extremely precocious gametophytization of the MMC that is nearly complete in the latter case and variably incomplete in the former two cases. Understanding how these precocious gametophytizations evolved and are regulated may be crucial to the eventual transfer of apomixis to major crop species and to its successful manipulation by breeders., Pure Callose is insoluble in water and is composed of glucans linked together by Β-1,3-glycosidic linkages. Normally, both Β-1,3- and Β-1,4- (cellulose) linkages occur in the same polysaccharide molecule. High [...]

Four [B.sub.III] hybrids (2n = 9x = 63, ABDStStYYWW) were obtained between wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) and a diplosporic and 2n-pollen-producing Elymus rectisetus (2n = 6x = 42, StStYYWW) accession. We determined whether apomeiosis and 2n pollen formation, which occur in the male parent, also occur in the Bill hybrids. Pistils were cleared for UV microscopy of callose and recleared for cytological observations using interference contrast microscopy. Callose fluorescence from most megaspore mother cells (MMCs) was typical of sexual species. These were classified as sexual. Abnormally elongated MMCs with walls devoid of callose were observed in 4.7% of pistils collected at meiotic prophase. These traits are typical of many apomeiotic MMCs in E. rectisetus. Asynapsis followed by mitosis in pollen mother cells (PMCs) consistently preceded unreduced pollen formation in E. rectisetus. This was not observed in the [B.sub.III] hybrids, though the following meiotic anomalies were observed: (i) asynapsis, aggregation of chromosomes to several poles, and multiple divisions to form four to eight unbalanced microspores, and (ii) incomplete synapsis, formation of anaphase I laggards, and a second division resulting in four unbalanced microspores with micronuclei. The wheat haplome enforced PMC meiotic pairing (albeit abnormal) among homologous E. rectisetus chromosomes and generally inhibited apomeiosis, also by enforcing meiosis. Diplospory may be caused by the expression of embryo sac signals from one genome precociously expressed with megasporogenesis signals from another. If this is correct, the successful induction of apomixis in wheat may require the transfer of alien gene cassettes that confer appropriate degrees of reproductive asynchrony., The Australian wheatgrass Elymus rectisetus reproduces by facultative diplospory. During the early apomeiotic prophase, vacuoles accumulate in the chalazal region of the MMC, the nucleus moves to the center of [...]

In mature plant breeding programs an elite core germplasm forms the backbone of the breeding effort, confronting the breeder with the challenge of maintaining germplasm diversity as genetic distance between the elite core germplasm and donor germplasm widens. This research assessed the effects on grain yield of transferring genes from two-row harley (Hordeum vulgare L.) cultivars to a six-row gene pool. We conducted three cycles of recurrent-type breeding, beginning with crosses involving five two-row donor parents. The crossing scheme led to progenies with theoretical proportions of two-row germplasm of 25 to 50% in Cycle 1, 12.5 to 25% in Cycle 2 and 6.25 to 12.5% in Cycle 3. In Cycle 1, yield of the six-row progeny across the five populations ranged from 86 to 97% of the respective six-row parent. Kernet weight of the six-row progeny was also low in Cycle 1. In Cycle 2, grain yield improved to 99% of the check mean and kernel weight improved to 102% of the check mean. In Cycle 3, sets of lines representing three populations yielded from 112 to 119% of the check mean in 1997 and 1998 and individual lines surpassed `Stander', the highest yielding check in both 1997 to 1998. The highest yielding lines in each cycle were derived from populations having the highest theoretical percentage of adapted recurrent parent germplasm, that is, when six-row gene combinations were predominately left intact. Results from the three breeding cycles support the proposition that a strategy that maintains favorable gene combinations while introgressing relatively small amounts of donor germplasm can lead to incremental yield gains., OLDER PLANT BREEDING PROGRAMS routinely have a core germplasm pool. Use of this core germplasm is important as the breeder attempts to create favorable gene combinations. Industry guidelines and market [...]