Warm-season Forage Research Articles

Protein supplementation of ruminants consuming low-quality cool- or warm-season forage: Differences in intake and digestibility

An in situ study (Exp. 1) using 4 ruminally cannulated steers (343 ± 11 kg of BW) in a completely randomized design was used to compare ruminal degradation characteristics of low-quality cool-season (C3; Kentucky bluegrass straw; Poa pratensis; 6.3% CP; DM basis) and warm-season (C4; tallgrass prairie; 5.7% CP; DM basis) forage. Four ruminally cannulated steers (252 ± 8 kg of BW; Exp. 2) and 4 wethers (38 ± 1 kg of BW; Exp. 3) were used in two 2 × 2 factorial arrangements of treatments to determine the influence of supplemental CP (CPSupp; soybean meal; 0.09 and 0.19% of BW, CP basis, for steers and lambs, respectively) on nutrient intake and digestion of C3 and C4 forages. Steers and wethers were allotted to separate 4 × 4 Latin squares that ran simultaneously with 20-d periods. In Exp. 1, C3 had a greater A fraction (fraction of total pool disappearing at a rate too rapid to measure) and effective degradability of DM and NDF compared with C4 (P < 0.01). In addition, C3 had a greater (P < 0.01) A fraction and effective degradability of N, whereas the C fraction (fraction of total pool unavailable in the rumen) was less (P < 0.01) than those for C4. Consequently, RDP accounted for 84.7% of total CP in C3 as compared with 66% for C4 (P < 0.01). In Exp. 2, a CPSupp × forage interaction (P < 0.01) was noted for forage and total DMI, with CPSupp increasing intake of C4 by 47% and intake of C3 forage by only 7%. Dry matter digestibility responded similarly, with a CPSupp × forage interaction (P = 0.05; CPSupp increased digestibility by 21% with C4 and by 9% with C3 forage). In addition, CPSupp × forage interactions were noted for ruminal liquid retention time (P = 0.02; CPSupp decreased retention by 3.6 h with C4 and by only 0.6 h with C3 forage) and particulate passage rate (P = 0.02; CPSupp increased passage by 46% with C4 and by 10% with C3 forage). As in Exp. 2, a CPSupp × forage interaction (P = 0.01; CPSupp increased digestibility by 18% with C4 and by 7% with C3 forage) was observed with DM digestibility in Exp. 3. In contrast, only N balance (P < 0.01) and N digestibility (P < 0.01) were affected by CPSupp. These data suggest that intake and digestion of low-quality C3 and C4 forages by ruminants are not similar and, more important, that the physiological response of ruminants to protein supplementation of low-quality forage is dependent on forage type.

난지형 목초 기니아그라스의 효율적인 캘러스 유도 및 식물체 재분화

Guineagrass (Panicum maximum Jacq.) is an important warm-season forage grass as well as biomass crop. It has both sexual and asexual mode of reproduction (apomictic) depending on cultivar. We developed efficient plant regeneration system for an apomictic (cv. Natsukaze) and a non-apomictic (Noh-PL1) guineagrass by optimizing the level of L-proline in the callus induction and that of AgNO3 in plant regeneration medium. Among the L-proline concentrations tested, the best callus induction was achieved by using 2g/L L-proline in both the genotypes. Immature embryos proved to be the best explant source for tissue culture of guineagrass. The highest frequency of shoot regeneration was obtained on MS plant regeneration medium supplemented with 2 mg/L AgNO3. These results provide a foundation for efficient tissue culture and genetic improvement of guineagrass. (Key words : L-proline, AgNO3, Immature embryo, Guineagrass, Shoot regeneration)

Integração lavoura e pecuária e os atributos físicos de solo manejado sob sistema plantio direto

Atributos físicos de solo foram avaliados num Latossolo Vermelho distrófico típico, em Passo Fundo, RS, dez anos após o estabelecimento (1993 a 2003) de cinco sistemas de produção integrando culturas produtoras de grãos, pastagens de inverno e forrageiras perenes: I) trigo/soja, aveia-branca/soja e ervilhaca/milho; II) trigo/soja, aveia-branca/soja e forrageiras anuais - aveia-preta + ervilhaca/milho; III) forrageiras perenes da estação fria - festuca + trevo-branco + trevo-vermelho + cornichão; IV) forrageiras perenes da estação quente - pensacola + aveia-preta + azevém + trevo-branco + trevo-vermelho + cornichão; e V) alfafa para feno, acrescentada em 1994, como tratamento adicional, com repetições em áreas contíguas ao experimento. Metade das áreas sob os sistemas III, IV e V retornou ao sistema I a partir do verão de 1996. As culturas, tanto de inverno como de verão, foram estabelecidas sob plantio direto. Os tratamentos foram distribuídos em blocos ao acaso com quatro repetições. Amostras de solo também foram coletadas em fragmento de floresta subtropical ao lado do experimento. O aumento da densidade do solo e da microporosidade, e a redução da porosidade total e da macroporosidade, devido aos distintos sistemas de produção de grãos com pastagens, não atingiram níveis capazes de promover degradação do solo. Os sistemas com pastagens perenes apresentaram menor densidade do solo e maior porosidade total e macroporosidade na camada 0-2 cm, em relação aos sistemas de produção de grãos ou produção de grãos com pastagens anuais.

Particle inflow gun-mediated transformation of multiple-shoot clumps in rhodes grass ( Chloris gayana)

Rhodes grass (Chloris gayana) is one of the most important warm-season forage grasses. It is cultivated in tropical and subtropical parts of the world and is mostly used for grazing and hay production. We have established a particle-bombardment transformation protocol for rhodes grass using multiple-shoot clumps (MSCs) as the target tissue. A vector pAHC25 containing a herbicide-resistance gene (bar) together with the beta-glucuronidase (GUS) gene was used in transformation experiments. The most efficient recovery of bialaphos-resistant tissue was achieved when the bombarded MSCs were first cultured for 15 d on bialaphos-free medium before being subjected to selection pressure. The resistant tissues regenerated transgenic plants that displayed GUS gene expression. Under optimized conditions, 251 target pieces yielded 46 transgenic plants from 4 independent transgenic lines.

Occurrence of the Wheat Stem Maggot, Meromyza americana Fitch (Diptera: Chloropidae), in Intermediate Wheatgrass, Thinopyrum intermedium (Host) Barkworth and D. R. Dewey (Poaceae), in Oklahoma1

The wheat stem maggot is primarily an economic pest of wheat, Triticum aestivum L.; barley, Hordeum vulgare L.; and cereal rye, Secale cereale L. (Poaceae) (Gilbertson, 1925; Allen and Painter, 1937; Rockwood et al., 1947). The larva of the wheat stem maggot enters the culm above the terminal node and feeds within the culm. Consequently, the developing inflorescence withers and dies and turns white in color. The aborted inflorescences are very noticeable among non-infested inflorescences. In Oklahoma, wheat stem maggot infestations have been reported to occur in seed production fields of bermudagrass, Cynodon dactylon var. dactylon (L.) Pers., and weeping love grass, Eragrostis curvula (Schrad.) Nees (Arnold and Ahring, 1987; Kindler et al., 1989). These were the first reported cases of wheat stem maggot to economically impact important warm-season forage grasses. Kindler et al. (1989) reported the percentage of aborted inflorescence in weeping lovegrass ranged from 3.2 to 22.6%. Intermediate wheatgrass, Thinopyrum intermedium (Host) Barkworth and D.R. Dewey, is an introduced forage grass that is used for pasture and hay for livestock in the Northern Great Plains, the Central and Southern High Plains, and much of the western United States. In the Southern Plains, research has shown that perennial, cool-season forage grasses do not persist through prolonged drought. Gillen and Berg (2005) reported a 95% reduction in stand due to drought where precipitation from September 2001 through May 2002 measured 62% of normal. Seeds from surviving plants from pastures used by Gillen and Berg were harvested in June 2002 and increased at the USDA-ARS Southern Plains Range Research Station, Woodward, Oklahoma. It was anticipated that progeny from these plants would have increased tolerance to drought. In late June 2006, aborted inflorescences of intermediate wheatgrass were found in a seed production block at Woodward. Aborted inflorescences were collected from the plot on 30 June, placed in Erlenmeyer flasks containing about 300 ml of tap water, and caged by placing them in a clear plastic bag with a nylon mesh screen on two sides to determine which insect was responsible (Kindler et al., 1989). Adult flies emerged 15–20 days later and were identified as wheat stem maggot using the keys of Sabrosky (1935) and Fedoseeva (1971). The percentage of aborted inflorescences was determined from randomly sampling 10 quadrats (30 3 30 cm) and ranged from 10 to 28%. Accordingly, the wheat stem maggot was confirmed as a pest of intermediate wheatgrass in Oklahoma which is a new host record. Voucher specimens were deposited at the K. C. Emerson Entomological Museum, Oklahoma State University, Stillwater.

Preweaning Performance of Calves from Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano Sires Bred to Brangus Cows Managed on Native Rangeland or Improved Forages ,

AbstractPreweaning data on 511 spring-born calves from 187 Brangus cows and 129 Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires were measured over a 4-yr period to determine sire breed, sex, and age of dam differences under 2 preweaning forage environments: 1) native tallgrass rangeland (native) or 2) improved warm-season forages (improved). Sire breed differences in birth weight varied across forage (P < 0.05) with Romosinuano-sired calves on improved forages ranked intermediate in birth weight compared with other sire breeds but lightest on native forages. Calves from Charolais and Gelbvieh tended to be heavier at 205 d of age than calves from other sire breeds on improved forages (P < 0.05, except Gelbvieh vs. Hereford, P < 0.12) whereas on native forages, Bonsmara-, Charolais-, and Gelbvieh-sired calves were similar but were heavier than Brangus- and Romosi-nuano-sired calves (P < 0.10). Steer calves were heavier than heifer calves on improved forages (P < 0.01) but not on native forages. Sire breed differences were not significant on improved forages for weaning condition score. On native forage, weaning condition scores were greater for calves sired by Bonsmara and Hereford (P < 0.05) compared with Brangus-, Charolais-, and Gelbvieh-sired calves, and Charolais-sired calves were lesser than other sire breeds (P < 0.05). These results provide evidence of nonadditive associations between preweaning forage systems, sire breed of calves, age of dam, and sex of calf in preweaning traits. Consideration should be given to appropriate combinations of these effects in development of efficient cow-calf production systems.

Carbon dioxide enrichment alters plant community structure and accelerates shrub growth in the shortgrass steppe.

A hypothesis has been advanced that the incursion of woody plants into world grasslands over the past two centuries has been driven in part by increasing carbon dioxide concentration, [CO(2)], in Earth's atmosphere. Unlike the warm season forage grasses they are displacing, woody plants have a photosynthetic metabolism and carbon allocation patterns that are responsive to CO(2), and many have tap roots that are more effective than grasses for reaching deep soil water stores that can be enhanced under elevated CO(2). However, this commonly cited hypothesis has little direct support from manipulative experimentation and competes with more traditional theories of shrub encroachment involving climate change, management, and fire. Here, we show that, although doubling [CO(2)] over the Colorado shortgrass steppe had little impact on plant species diversity, it resulted in an increasingly dissimilar plant community over the 5-year experiment compared with plots maintained at present-day [CO(2)]. Growth at the doubled [CO(2)] resulted in an approximately 40-fold increase in aboveground biomass and a 20-fold increase in plant cover of Artemisia frigida Willd, a common subshrub of some North American and Asian grasslands. This CO(2)-induced enhancement of plant growth, among the highest yet reported, provides evidence from a native grassland suggesting that rising atmospheric [CO(2)] may be contributing to the shrubland expansions of the past 200 years. Encroachment of shrubs into grasslands is an important problem facing rangeland managers and ranchers; this process replaces grasses, the preferred forage of domestic livestock, with species that are unsuitable for domestic livestock grazing.

Warm Season (Summer) Forage Legume Guide

Revised! SS-AGR-48, a 5-page guide by Y.C. Newman and C. G. Chambliss, provides an overview of summer forage legume crops: inoculation of seeds, cultivars, planting, fertilization, irrigation, and management and utilization for both pasture and hay. Includes a table of planting dates, seeding rates, and planting depths for various forage legume crops. Published by the UF Department of Agronomy, May 2007.

CATERPILLAR (LEPIDOPTERA: NOCTUIDAE) FEEDING ON PASTURE GRASSES IN CENTRAL FLORIDA

Abstract Stargrasses (Cynodon nlemfuensis Vanderyst var. nlemfuensis) and bermudagrasses (C. dactylon (L.) Persoon) are important warm-season forage grasses, with several cultivars developed for conditions found in central and southern Florida. Major insect pests of these grasses include grass loopers (Mocis spp.) and fall armyworm (Spodoptera frugiperda (J. E. Smith)), which annually may impose economic losses for beef cattle and hay producers. Population studies conducted during a 3-year period showed that both species had similar profiles with respect to larval population seasonality but not abundance. Plot studies with 4 stargrass and 4 bermudagrass lines showed that higher grass looper populations were found in stargrasses than bermudagrasses. Laboratory studies found grass loopers and fall armyworm larvae generally developed faster with larger weights on lines of stargrass than lines of bermudagrass. The two fall armyworm host strains also can differ substantially in their larval weight, development...

Comportamento ingestivo de vacas holandesas em lactação em pastagens de capim-elefante anão (Pennisetum purpureum cv. Mott) e Tifton 85 (Cynodon dactylon x C. nlemfuensis) na região noroeste do Estado do Rio Grande do Sul

O objetivo deste trabalho foi avaliar a influência de duas espécies forrageiras perenes de estação quente, de estruturas e hábitos de crescimento diferentes, representadas por capim elefante anão e Tifton 85, sobre o comportamento ingestivo de vacas holandesas em lactação. Nas avaliações do comportamento ingestivo, foi utilizado o método direto de observação visual de animais, em dois períodos de 20 horas, em 22-23/12/2004 e 25-26/01/2005, com início e término às oito horas, durante a estação de crescimento da pastagem. A cada intervalo de 10 minutos, foram registrados os tempos das atividades: de pastejo, de ruminação, de ócio (min dia-1), taxa de bocados (no min-1), tempo de permanência por estação alimentar (segundos) e distância entre estações alimentares (metros). Calculou-se também a massa de folhas disponíveis. As espécies estudadas não influenciaram os componentes do comportamento ingestivo: tempo diário de pastejo, de ruminação e de ócio nem a taxa de bocados. O tempo de permanência por estação alimentar foi superior e a distância percorrida entre estações alimentares foi inferior para a pastagem de Tifton 85, melhorando a "eficiência de colheita" pelos animais nessa espécie forrageira, que demostrou superioridade (produção foliar e resistência) quando comparada à pastagem de capim elefante anão.

A genetic map of tetraploid Paspalum notatum Flügge (bahiagrass) based on single-dose molecular markers

Paspalum notatum Flügge is a warm-season forage grass with mainly diploid (2n = 20) and autotetraploid (2n = 40) representatives. Diploid races reproduce sexually and require crosspollination due to a self-incompatible mating system, while autotetraploids reproduce by aposporous apomixis. The objectives of this work were to develop a genetic linkage map of Paspalum notatum Flügge at the tetraploid level, identify the linkage/s group/s associated with apomixis and carry out a general characterization of its mode of inheritance. A pseudo test-cross F1 family of 113 individuals segregating for the mode of reproduction was obtained by crossing a synthetic completely sexual tetraploid plant (Q4188) as female parent with a natural aposporous individual (Q4117) as pollen donor. Map construction was based on single-dose markers (SDAFs) segregating from both parents. Two linkage maps (female and male) were constructed. Within each map, homologous groups were assembled by detecting repulsion-phase linked SDAFs. Putative Q4188 and Q4117 homolog groups were identified by mapping shared single dose markers (BSDF). The Q4188 map consisted of 263 markers distributed on 26 co-segregation groups over a total genetic distance of 1.590.6 cM, while the Q4117 map contained 216 loci dispersed on 39 co-segregation groups along 2.265.7 cM, giving an estimated genome coverage of 88% and 83%, respectively. Seven and 12 putative homologous chromosomes were detected within Q4188 and Q4117 maps, respectively. Afterward, ten female and male homologous chromosomes were identified by mapping BSDFs. In the Q4117 map, a single linkage group was associated with apospory. It was characterized by restriction in recombination and preferential chromosome pairing. A BPSD marker mapping within this group allowed the detection of the female homolog and the putative four male groups of the set carrying apospory.

Forage production of tropical grasses under extended daylength at subtropical and tropical latitudes

Decreased growth of warm-season forage grasses during subtropical winters has been shown to be a response to short-daylength during those months. The objective of this research was to evaluate the influence of short-daylength on growth of forage grasses in low latitude locations. Three grasses (Argentine bahiagrass, Paspalum notatum Flügge; Common guineagrass, Panicum maximum Jacq.; Tifton-85 bermudagrass, Cynodon spp. Pers.) were grown at three locations (south Florida, Puerto Rico, and St. Croix) under extended (15 h) and natural daylength during 2 years. Plots were harvested at 5-week (October–February) and 4-week (March–April) intervals to measure dry matter (DM) yield and nutritive value of the herbage. Daylength effects were found on DM harvested for all grasses in south Florida ( P < 0.01). At that location, grasses exposed to increased daylength averaged a 44% increase in DM harvested compared to those grown under natural daylength. Daylength effects were consistent for bahiagrass at the other two locations as well. However, guineagrass and bermudagrass did not respond to extended daylength in Puerto Rico and St. Croix. These results showed that bahiagrass is capable of producing additional forage during the cool season at all locations tested if sensitivity to photoperiod is genetically removed or attenuated.

Five Year‐Round Forage Systems in a Dairy Effluent Sprayfield

In northern Florida, forages are grown in dairy effluent sprayfields to recover excess P. Our purpose was to evaluate five year-round forage systems for their capacity to remove P from a dairy sprayfield. The soil is a Kershaw sand (thermic, uncoated Typic Quartzipsamment). Systems included bermudagrass (Cynodon spp.)-rye (Secale cereale L.) (BR), perennial peanut (Arachis glabrata Benth.)-rye (PR), corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye (CSR), corn-bermudagrass-rye (CBR), and corn-perennial peanut-rye (CPR). Forages were grown for five 12-mo cycles. Effluent P rates were 80, 120, and 165 kg ha-1 cycle-1. The 5-cycle P removal was 67 kg ha-1 cycle-1 for BR, 54 kg ha-1 for CBR, 52 kg for CSR, 45 kg for PR, and 43 for CPR. Removal of P by winter rye was low. There were differences in system rankings among cycles primarily due to changes in the performance of perennial forages. In the first two cycles, BR had the greatest P removal (91 kg ha-1 cycle-1) due to high bermudagrass yield and P concentration. In the first cycle, P removal was lowest for PR (36 kg ha-1) because perennial peanut was slow to establish. In later cycles, P removal for BR declined because bermudagrass yield and P concentration declined. It increased for PR because peanut yield increased. The yield of corn in CBR, CPR, and CSR was consistently high but P concentration was modest (avg. 2.2 g kg-1). Sorghum produced moderate but stable yield and had low P levels (avg. 1.8 g kg-1). Effluent rate marginally affected the performance of most grasses. For P recovery in dairy sprayfields in northern Florida, the best warm-season forage would likely be a high yielding, persistent bermudagrass.

Agrobacterium-Mediated Transformation of Common Bermudagrass (Cynodon dactylon)

Common bermudagrass, Cynodon dactylon, is a widely used warm-season turf and forage species in the temperate and tropical regions of the world. We have been able to transform the species using Agrobacterium-mediated approach. In seven experiments reported here, a total of 67 plates of calluses and suspensions were infected with Agrobacterium tumefaciens strains, and nine hygromycin B resistant calluses were obtained after selection. Among them two green independent transgenic plants were recovered. The plants growing in pots looked relatively compact at the beginning, but the ploidy level of the plants, as determined by nuclear DNA content, was not altered.

Green, herbicide-resistant plants by particle inflow gun-mediated gene transfer to diploid bahiagrass ( Paspalum notatum)

We have established an efficient particle-bombardment transformation protocol for the diploid non-apomictic genotype of the warm season forage crop Paspalum notatum (bahiagrass). A vector containing a herbicide resistance gene (bar) together with the GUS reporter gene was used in transformation experiments. The bar gene confers resistance to the herbicide bialaphos. An improved culture system, highly regenerative callus, dense in compact polyembryogenic clusters, was produced on medium with a high CuSO4 content at elevated temperature. Target tissue (360 calli) produced under these conditions yielded 52 rooted plants on herbicide-containing medium, and 22 of these plants were PCR-positive. DNA gel blot analysis revealed a copy number of 1-5 for the GUS gene in different independent transformants. There was no correlation between copy number and GUS activity. While conventional cultures yielded exclusively albino plants on herbicide-containing medium, improved culture conditions for the target tissue resulted in the recovery of 100% green transgenic plants. All green herbicide-resistant regenerants were morphological normal and fertile.

`Prairie Chief' Big Bluestem

While the use of prairie plants in midwestern landscapes is currently going through a resurgence (Smith and Smith, 1980; Wasowski, 2002), the concept is firmly rooted in the past. Wilhelm Miller (1915) wrote, “Every Illinois city should have in at least one park a ‘prairie border’–with the grasses, composites, and other flowers labeled.” Astute designers realized that native prairie species are often adapted to Midwestern soils, climate, and pests, which can reduce maintenance practices such as supplemental irrigation, fertilization, and pesticide use. The reduction in materials and labor resulting from landscaping with native plants over a 10-year period may be one-fifth the cost of conventional landscape plantings (Mariner et al., 1997). Horticultural selections of prairie forbs (e.g., Aster novae-angliae, Echinacea purpurea, Liatris spicata, and Rudbeckia hirta) are common. Conversely, other than switch grass (Panicum virgatum) and little bluestem (Schizachyrium scoparium), horticultural selections of native ornamental grasses are relatively uncommon; presently, most ornamental grasses planted in the Midwest are exotics, often from the genera Calamagrostis, Miscanthus, and Pennisetum. Native grasses in the genus Andropogon (the bluestems), particularly A. gerardii, deserve more landscape attention. Greenlee (1992) noted that named cultivars of Andropogon would soon be introduced into the U.S. landscape trade due to their heights and foliage colors. Andropogon gerardii Vitman, big bluestem or turkey-foot, has been shown to be particularly diverse morphologically, ecologically, cytologically, and genetically (Barnes 1985, 1986; Gustafson et al., 1999; Keeler and Davis, 1999; Keeler et al., 2002; Wipff, 1996), all indicative of high potential for horticultural selection. Andropogon is a large genus of ≈100 species, comprised of perennial grasses found in temperate and tropical climates (Mabberley, 1997; Watson and Dallwitz, 1994). Members of the genus are commonly referred to as bluestems or beardgrasses; the name bluestem describes the bluish bloom on stems of some species within the genus (Mosher, 1918). The term beardgrass is a literal interpretation of the genus name Andropogon, which was derived from the Greek andro (man) and pogon (beard). This name is in reference to the hairy rachis and pedicels of sterile spikelets (Fernald, 1950). The specific epithet, gerardii, honors the French botanist, Louis Gerard, who informally described the species from plants cultivated in Provence (Fernald, 1950). Members of the genus Andropogon are quite common in much of the U.S.; there are 15 species in the continental U.S. (Kartesz and Meacham, 1999). Big bluestem (Andropogon gerardii), a primary component of the tallgrass prairie, is typically found in mesic areas, but can also occur in xeric or wet prairies (Ladd, 1995; Stubbendieck et al., 1997). Big bluestem is found from Quebec and Maine to Saskatchewan and Montana, south to Florida, Wyoming, Utah, and Arizona and also in Mexico and Honduras (Fernald, 1950; Hitchcock 1950; Kartesz and Meacham, 1999). Big bluestem is highly regarded as a livestock forage crop (Stubbendieck, 1997). Selections have been made for forage production as well as range and pasture plantings. For example, A. gerardii ‘Niagara’ is used for warm season forage production, re-vegetating droughty sites, and wildlife habitat improvement (Alderson and Sharp, 1995). Unique characteristics of ‘Niagara’ include a wide flag leaf, rapid regrowth in late summer and early fall, and some resistance to leaf spot (Alderson and Sharp, 1995). Other varieties such as ‘Kaw’ and ‘Pawnee’ (Reg. No. 1) are also used for range and pasture plantings. ‘Kaw’ displays uniform distribution of leaves, some resistance to rust, relatively high seed yields. ‘Pawnee’ produces good forage yields in Nebraska; seed quality and seed yields in cultivated rows and under irrigation are superior to common strains (Alderson and Sharp, 1995). In landscapes, Andropogon gerardii has traditionally been relegated to naturalized plantings such as prairie restoration, but can also be used as a background plant or screen (Greenlee, 1992). Its height (typically 1.5 to 2.4 m), upright growth habit, and orange to copper-red fall color identify it as a potential landscape plant (Darke, 1999). Cultivars of big bluestem have rarely been selected for ornamental planting. Exceptions are ‘Sentinel’ and ‘Champ’. ‘Sentinel’ (Limerock Ornamental Grasses, Inc., Port Matilida, Pa.) is similar in height, floral morphology, and cultural and propagation requirements to the species. Its narrow, columnar growth habit and burgundy tinted with yellow and orange suffused with blue fall color distinguish it from other big bluestems (Norm Hooven, Limerock Ornamental Grasses, Inc., personal communication). ‘Champ’ was originally selected as a forage type (Alderson, and Sharp, 1995; Newell, 1968), but Greenlee (1992) includes it with ornamental grasses due to its fall color and tolerance to sandy growing sites. Herein, another A. gerardii cultivar, ‘Prairie Chief’, is being introduced for landscape planting. It displays an upright habit that is slightly more open than ‘Sentinel’, and red, purple, and orange fall color. Furthermore, based on its habit and height, ‘Prairie Chief’ provides a native replacement for several exotic grasses

Yield and nutritive quality of sericea lespedeza ( Lespedeza cuneata) and little bluestem ( Schizachyrium scoparium) exposed to ground-level ozone

Sericea lespedeza ( Lespedeza cuneata cv. Interstate 76) and little bluestem ( Schizachyrium scoparium cv. Aldous) were raised from seed in a glasshouse, transplanted into 5.7-l pots and placed into open-top chambers (OTC) on 6 June 1999. Following a 7-day adjustment period, each of six OTCs (duplicate OTCs per treatment) was ventilated with either air that had been carbon-filtered (CF) to remove ambient ozone (O 3); non-filtered (NF), representative of ambient air; or enriched to twice-ambient O 3 concentration (2X). Primary-growth forage was harvested on days 7, 32, 46, 59 and 72 following the start of fumigation, and regrowth forage from the first primary-growth harvest was harvested on days 36, 54 and 72 following the start of fumigation. Dry matter (DM) yield of either forage species did not differ among treatments except in the final regrowth period when yield of sericea lespedeza was greater for the NF than 2X O 3 treatment. In vitro DM digestibility (IVDMD) and concentrations of crude protein (CP), soluble phenolics (SP) and condensed tannins (CT) in primary-growth sericea lespedeza did not differ between treatments, but NF primary-growth forage had higher concentration of protein-precipitating tannins (PPT) than did 2X primary-growth forage. Concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in NF and 2X than in CF primary-growth sericea lespedeza. Similarly, concentrations of NDF and ADL were higher, and IVDMD was lower for NF and 2X than for CF regrowth sericea lespedeza. Concentrations of ADF and ADL were lower, whereas IVDMD, in vitro NDF digestibility (IVNDFD) and concentrations of CP and SP were greater, in CF than in NF and 2X primary-growth little bluestem. Percentages IVDMD and IVNDFD and concentrations of CP and SP in NF primary-growth little bluestem were greater than those in forage exposed to 2X O 3 treatment. No significant differences were observed among treatments in percentages IVDMD and IVNDFD, or concentrations of cell wall constituents or SP in little bluestem regrowth. Nutritive quality of little bluestem was decreased by <2%, and that of sericea lespedeza by ∼7% as a result of increased concentrations of cell wall constituents and decreased in vitro digestibility of NF and 2X compared with CF forages. Results indicate that existing and projected O 3 levels can drive alterations in forage quality of select warm-season forages sufficient to have nutritional and economic implications for their utilization by ruminant herbivores.

Bermudagrass–White Clover–Bluegrass Sward Production and Botanical Dynamics

Cool-season forages dominate pastures in the Appalachian region where midsummer weather conditions often depress productivity. Warm-season forages can buffer variation in available herbage, but land resources may limit the area dedicated to special-use crops. A replicated field plot experiment was conducted for 3 yr (1995–1997) in a bermudagrass (Cynodon dactylon L.) stand oversown with Kentucky bluegrass (Poa pratensis L.) and white clover (Trifolium repens L.) to determine the influence of defoliation on productivity, nutritive value, and botanical dynamics of the mixture. Botanical composition changed with defoliation and varied among years. Bermudagrass comprised as much as 55% of the sward in mid- and late-season 1995. By 1997, the proportion was similar to other grasses and rarely exceeded 20%. Maximum instantaneous growth rates occurred later in the growing season in 1995 when bermudagrass was a dominant sward component compared with subsequent years when bermudagrass was <10% of the sward. Rates in 1995 were greatest for swards clipped at 6-wk intervals (70 kg ha−1 d−1) or when 20-cm tall and least when clipped at 2-wk intervals (33 kg ha−1 d−1) and at 10-cm height (45 kg ha−1 d−1). The trend was reversed by 1997 when sward composition shifted away from bermudagrass to cool-season grasses and white clover. Yields were greatest when cool-season species dominated the sward. Creating a self-regulating mixture of warm- and cool-season perennial forages may be a means of achieving some stability in sward productivity and might be useful where wide fluctuations in growing conditions occur among years.

Optimizing embryogenic callus production and plant regeneration from 'Tifton 9' bahiagrass seed explants for genetic manipulation

Bahiagrass (Paspalum notatum Flugge) is a warm season forage grass widely cultivated in southeastern U.S. and South America. The cultivar Tifton 9 has several desirable characteristics such as high forage yield, more vigor at the seedling stage, etc.; but its forage quality is very low. As an initial step for future genetic manipulations to improve its forage characteristics, we have optimized in vitro culture conditions for plant regeneration. In this report, we describe an efficient method for embryogenic callus induction and plant regeneration from bahiagrass (cv. Tifton 9) seed explants, which are readily available and easy to manipulate, compared to other explant sources reported in the literature. Murashige and Skoog (MS) medium containing 30 μM dicamba and 5 μM 6-benzyladenine (BA) was optimal for callus induction and growth. Out of 9734 seeds cultured, 65.7% germinated and 21.4% produced embryogenic callus on this medium. Shoot formation was best when embryogenic calluses induced in this medium were transferred to MS medium supplemented with 5 μM BA and 1 μM gibberellic acid with 1640 plantlets formed per gram fresh weight of callus tissue. When transferred to hormone-free SH medium, shoot systems produced well-developed root systems. The resulting plantlets grew normally produced viable seeds when transferred to soil in the greenhouse. Histochemical staining for GUS activity arising from transient expression of the introduced uidA (β-glucuronidase) gene indicated that bahiagrass embryogenic callus produced by this method is suitable for gene transfer via biolistic bombardment; and it can serve as a good target tissue for future genetic manipulations to improve the forage quality of bahiagrass (cv. Tifton 9).

Hand-Plucked Forage Yield and Quality and Seed Production from Annual and Short-Lived Perennial Warm-Season Legumes Fertilized with Composted Manure

Productive warm-season forage legume species adapted to drier regions of the southeastern USA have yet to be identified. This trial evaluated adaptability, forage quality, hand-plucked forage yield, and seed production of legumes in north-central Texas as affected by dairy manure compost and harvest deferment. For 2 yr, eight warm-season annual or short-lived perennial legume species, with or without 20 Mg dairy manure compost ha−1 yr−1 added to the soil, were either hand-plucked monthly throughout the season or once-only in the autumn. Compost increased (P < 0.05) forage P and crude protein (CP) concentrations and plant-available soil P by the end of the trial. Phasey bean [Macroptilium lathyroides (DC) Urb.], peanut (Arachis hypogaea L.) and ‘iron-clay’ cowpea [Vigna unguiculata (L.) Walp.]) harvested throughout the season yielded over 2.5 Mg of high quality forage ha−1 yr−1 during the higher rainfall year. Autumn-only harvests produced lower yields but “Tecomate” lablab [Lablab purpureus (L.) Sweet] and peanut responded to autumn rainfall in the higher rainfall year with yields over 1.7 Mg ha−1 yr−1 Forage yields were less than 1.0 Mg ha−1 yr−1 during the second year when plots received only 358 mm of moisture from January through September. Both partridge pea [Chameacrista fasciculata (Michx) Greene] and phasey bean produced over 5000 seed ha−1 yr−1 the higher rainfall year under autumn-only harvest and over 1200 seed ha−1 yr−1 under all-season harvest. Quality of the herbage changed with precipitation, species, and harvest. Although not highly productive under dryland conditions, these legumes can contribute both forage and seeds for livestock and wildlife.