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R D Williams - One of the best experts on this subject based on the ideXlab platform.

  • pasture residue amount and sowing method effects on establishment of overseeded Cool Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

  • Pasture residue amount and sowing method effects on establishment of overseeded Cool‐Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

  • seeding Cool Season Grasses into unimproved warm Season pasture in the southern great plains of the united states
    Grass and Forage Science, 2008
    Co-Authors: P W Bartholomew, R D Williams
    Abstract:

    Limited availability of herbage during the Cool Season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six Cool-Season Grasses were individually sown into clean-tilled ground, no-till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no-till over-sown into dormant unimproved warm-Season pastures. The dry matter (DM) yields of mixtures of Cool and warm-Season herbage species were measured to test their potential for increasing Cool-Season herbage production in a low-input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year-round DM yields than undisturbed warm-Season pasture with all establishment methods. When Cool-Season grass was no-till seeded into existing warm-Season pasture, there was on average a 0·61 kg DM increase in year-round herbage production for each 1·0 kg DM of Cool-Season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean-tilled ground, required 700 or 1400 kg DM ha−1, respectively, of Cool-Season production before the year-round DM yield of each species equalled that of undisturbed warm-Season pasture. Productive pastures of perennial Cool-Season Grasses were not sustained beyond two growing Seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of Cool-Season perennial Grasses for over-seeding unimproved warm-Season pasture in the southern Great Plains.

  • Seeding Cool‐Season Grasses into unimproved warm‐Season pasture in the southern Great Plains of the United States
    Grass and Forage Science, 2008
    Co-Authors: P W Bartholomew, R D Williams
    Abstract:

    Limited availability of herbage during the Cool Season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six Cool-Season Grasses were individually sown into clean-tilled ground, no-till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no-till over-sown into dormant unimproved warm-Season pastures. The dry matter (DM) yields of mixtures of Cool and warm-Season herbage species were measured to test their potential for increasing Cool-Season herbage production in a low-input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year-round DM yields than undisturbed warm-Season pasture with all establishment methods. When Cool-Season grass was no-till seeded into existing warm-Season pasture, there was on average a 0·61 kg DM increase in year-round herbage production for each 1·0 kg DM of Cool-Season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean-tilled ground, required 700 or 1400 kg DM ha−1, respectively, of Cool-Season production before the year-round DM yield of each species equalled that of undisturbed warm-Season pasture. Productive pastures of perennial Cool-Season Grasses were not sustained beyond two growing Seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of Cool-Season perennial Grasses for over-seeding unimproved warm-Season pasture in the southern Great Plains.

P W Bartholomew - One of the best experts on this subject based on the ideXlab platform.

  • nitrogen application for spring growth of Cool Season Grasses overseeded in unimproved warm Season pasture
    Crop Forage and Turfgrass Management, 2015
    Co-Authors: P W Bartholomew
    Abstract:

    In the southern Great Plains fall overseeding of annual forages into dormant warm-Season pasture can increase herbage production in spring and early summer of the following year, but production in early spring, when it is most needed, is usually limited and competition between Cool- and warm-Season components of mixed pasture may result in only small benefit in total annual yield. The effects of early-producing species, or of stimulation of early growth by nitrogen (N) fertilizer application to the Cool-Season crop, on early-Season availability of herbage and on competition within mixed pasture were evaluated in a series of experiments. Rye (Secale cereale L.), oats (Avena sativa L.), or annual ryegrass (Lolium multiflo rum Lam.) were overseeded into dormant unimproved warm-Season pasture in fall and provided 22, 45, or 67 lb/acre of N fertilizer in mid-February of the following year. Neither rye nor annual ryegrass showed significant advance in early-Season growth (up to early April) resulting from increased N application, and herbage dry matter (DM) yield response was <4.0 lb DM/lb N applied over this period. Over uninterrupted spring growth to a mid-May harvest, DM yield responses to applied N were similar in rye and annual ryegrass and ranged from 9.3 to 32.3 lb DM/lb N. Oats did not tolerate low winter temperatures. Choice of Cool-Season annual grass species for overseeding and level of N application in spring had little impact on DM yield of the warm-Season grass component of mixed Cool- and warm-Season pasture.

  • pasture residue amount and sowing method effects on establishment of overseeded Cool Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

  • Pasture residue amount and sowing method effects on establishment of overseeded Cool‐Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

  • seeding Cool Season Grasses into unimproved warm Season pasture in the southern great plains of the united states
    Grass and Forage Science, 2008
    Co-Authors: P W Bartholomew, R D Williams
    Abstract:

    Limited availability of herbage during the Cool Season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six Cool-Season Grasses were individually sown into clean-tilled ground, no-till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no-till over-sown into dormant unimproved warm-Season pastures. The dry matter (DM) yields of mixtures of Cool and warm-Season herbage species were measured to test their potential for increasing Cool-Season herbage production in a low-input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year-round DM yields than undisturbed warm-Season pasture with all establishment methods. When Cool-Season grass was no-till seeded into existing warm-Season pasture, there was on average a 0·61 kg DM increase in year-round herbage production for each 1·0 kg DM of Cool-Season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean-tilled ground, required 700 or 1400 kg DM ha−1, respectively, of Cool-Season production before the year-round DM yield of each species equalled that of undisturbed warm-Season pasture. Productive pastures of perennial Cool-Season Grasses were not sustained beyond two growing Seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of Cool-Season perennial Grasses for over-seeding unimproved warm-Season pasture in the southern Great Plains.

  • Seeding Cool‐Season Grasses into unimproved warm‐Season pasture in the southern Great Plains of the United States
    Grass and Forage Science, 2008
    Co-Authors: P W Bartholomew, R D Williams
    Abstract:

    Limited availability of herbage during the Cool Season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six Cool-Season Grasses were individually sown into clean-tilled ground, no-till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no-till over-sown into dormant unimproved warm-Season pastures. The dry matter (DM) yields of mixtures of Cool and warm-Season herbage species were measured to test their potential for increasing Cool-Season herbage production in a low-input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year-round DM yields than undisturbed warm-Season pasture with all establishment methods. When Cool-Season grass was no-till seeded into existing warm-Season pasture, there was on average a 0·61 kg DM increase in year-round herbage production for each 1·0 kg DM of Cool-Season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean-tilled ground, required 700 or 1400 kg DM ha−1, respectively, of Cool-Season production before the year-round DM yield of each species equalled that of undisturbed warm-Season pasture. Productive pastures of perennial Cool-Season Grasses were not sustained beyond two growing Seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) × bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of Cool-Season perennial Grasses for over-seeding unimproved warm-Season pasture in the southern Great Plains.

Joseph G Robins - One of the best experts on this subject based on the ideXlab platform.

  • genotype environment interaction patterns in rangeland variety trials of Cool Season Grasses in the western united states
    Agronomy, 2020
    Co-Authors: Joseph G Robins, Craig W Rigby, Kevin B Jensen
    Abstract:

    Rangeland revegetation is necessary to stabilize disturbed sites and increase forage production, but frequently fails due to a variety of environmental and biotic factors. Plant breeding efforts in perennial Cool-Season Grasses result in the development of potential cultivars that must be evaluated in multi-environment trials to determine their level of adaptation. This study evaluated 49 cultivars for stand frequency and dry matter yield over five years at five environments in the Intermountain and High Plains regions of the United States. The results were significant differences among the included cultivars for both traits across and within environments. Yet, there was also crossover genotype × environment interaction. Thus, highest performing cultivars were to some extent dependent on the environment. Hycrest II crested wheatgrass and Vavilov II Siberian wheatgrass possessed high stand frequency (>80 %) and dry matter yield (>800 kg·ha−1) across environments and within environments except at the Eureka, UT environment where they possessed low stand frequency. These cultivars, and species, also possessed high productivity and stability for both traits. Thus, breeding efforts in the species resulted in widely adapted cultivars that may lack specific adaptation to some environments.

  • Genotype × Environment Interaction Patterns in Rangeland Variety Trials of Cool-Season Grasses in the Western United States
    Agronomy, 2020
    Co-Authors: Joseph G Robins, Craig W Rigby, Kevin B Jensen
    Abstract:

    Rangeland revegetation is necessary to stabilize disturbed sites and increase forage production, but frequently fails due to a variety of environmental and biotic factors. Plant breeding efforts in perennial Cool-Season Grasses result in the development of potential cultivars that must be evaluated in multi-environment trials to determine their level of adaptation. This study evaluated 49 cultivars for stand frequency and dry matter yield over five years at five environments in the Intermountain and High Plains regions of the United States. The results were significant differences among the included cultivars for both traits across and within environments. Yet, there was also crossover genotype × environment interaction. Thus, highest performing cultivars were to some extent dependent on the environment. Hycrest II crested wheatgrass and Vavilov II Siberian wheatgrass possessed high stand frequency (>80 %) and dry matter yield (>800 kg·ha−1) across environments and within environments except at the Eureka, UT environment where they possessed low stand frequency. These cultivars, and species, also possessed high productivity and stability for both traits. Thus, breeding efforts in the species resulted in widely adapted cultivars that may lack specific adaptation to some environments.

  • evaluation of warm Season Grasses nutritive value as alternatives to Cool Season Grasses under limited irrigation
    Grassland Science, 2016
    Co-Authors: Joseph G Robins
    Abstract:

    The production of Cool-Season Grasses is limited by their photosynthetic inefficiency during the hot summer months. Therefore, a study was conducted during 2006 and 2007 at a Logan, UT, USA field site to determine the potential of various warm-Season Grasses as alternatives to Cool-Season Grasses during summer under limited irrigation. The study included 20 environments, which corresponded to combinations of the 2 years, two harvest dates (June and July) and five irrigation levels. There were differences among the 27 varieties (21 warm-Season and six Cool-Season) for crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), neutral detergent fiber digestibility (NDFD), water soluble carbohydrates (WSC) and biomass (BM) across the 20 environments. However, the overall variety effects were ameliorated by the presence of genotype by environment interaction for CP, WSC, BM, and to a lesser extent IVTD. The Cool-Season Grasses generally possessed higher trait values in each environment, yet there were several warm-Season Grasses, such as big bluestem (Andropogon gerardii Vitman) variety ‘Bison’ and switchgrass (Panicum virgatum L.) variety ‘Trailblazer’ that possessed higher values for the nutritive value traits. Additionally, these warm-Season grass varieties possessed substantially higher BM than any Cool-Season grass varieties. Thus, there are warm-Season grass varieties that combine high BM and higher nutritive value in the summer months under limited irrigation. These may prove to be viable forage alternatives to the Cool-Season Grasses during the summer slump period.

  • Evaluation of warm‐Season Grasses nutritive value as alternatives to Cool‐Season Grasses under limited irrigation
    Grassland Science, 2016
    Co-Authors: Joseph G Robins
    Abstract:

    The production of Cool-Season Grasses is limited by their photosynthetic inefficiency during the hot summer months. Therefore, a study was conducted during 2006 and 2007 at a Logan, UT, USA field site to determine the potential of various warm-Season Grasses as alternatives to Cool-Season Grasses during summer under limited irrigation. The study included 20 environments, which corresponded to combinations of the 2 years, two harvest dates (June and July) and five irrigation levels. There were differences among the 27 varieties (21 warm-Season and six Cool-Season) for crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), neutral detergent fiber digestibility (NDFD), water soluble carbohydrates (WSC) and biomass (BM) across the 20 environments. However, the overall variety effects were ameliorated by the presence of genotype by environment interaction for CP, WSC, BM, and to a lesser extent IVTD. The Cool-Season Grasses generally possessed higher trait values in each environment, yet there were several warm-Season Grasses, such as big bluestem (Andropogon gerardii Vitman) variety ‘Bison’ and switchgrass (Panicum virgatum L.) variety ‘Trailblazer’ that possessed higher values for the nutritive value traits. Additionally, these warm-Season grass varieties possessed substantially higher BM than any Cool-Season grass varieties. Thus, there are warm-Season grass varieties that combine high BM and higher nutritive value in the summer months under limited irrigation. These may prove to be viable forage alternatives to the Cool-Season Grasses during the summer slump period.

  • Cool Season Grasses produce more total biomass across the growing Season than do warm Season Grasses when managed with an applied irrigation gradient
    Biomass & Bioenergy, 2010
    Co-Authors: Joseph G Robins
    Abstract:

    Abstract Warm-Season Grasses have shown great potential for biomass production. However, their productivity under irrigated conditions has not been thoroughly documented. This study evaluated the biomass production potential and production stability of a number of warm- and Cool-Season Grasses across an irrigation gradient. Under the multiple-harvest management strategy, the Cool-Season Grasses were most productive across the entire growing Season. Nevertheless, when considering only the summer harvests, the switchgrass and big bluestem entries were the most productive, although the lowland cultivar Alamo did not perform well under the conditions. Overall, Cool-Season Grasses were clearly the most productive for total biomass production across the growing Season. However, based on the high biomass production of switchgrass, this species may have potential as a high-producing option for animal feed during the summer months when the Cool-Season Grasses are unproductive.

J M Schneider - One of the best experts on this subject based on the ideXlab platform.

  • pasture residue amount and sowing method effects on establishment of overseeded Cool Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

  • Pasture residue amount and sowing method effects on establishment of overseeded Cool‐Season Grasses and on total annual production of herbage
    Grass and Forage Science, 2011
    Co-Authors: P W Bartholomew, J M Schneider, R D Williams
    Abstract:

    Warm-Season pasture residue may create problems for no-till overseeding with Cool-Season Grasses in the USA Southern Plains. Removal of residue to facilitate overseeding, however, represents additional cost and labour that may not be available on small livestock farms. Field experiments were undertaken to assess the effects of above-surface residues of warm-Season pasture averaging 1·62, 2·48 or 3·36 t DM ha−1 on establishment and herbage production of Italian ryegrass (Lolium multiflorum) or tall fescue (Festuca arundinacea) overseeded by broadcasting or by no-till drilling into dormant warm-Season pasture. On average, no-till drilling was more effective than broadcasting in establishing both grass species, but it was no more effective than broadcasting when used with the greatest amount of residue. Cool-Season grass production was increased by 0·16 when no-till drilled, but combined yearly total herbage production of Cool- and warm-Season Grasses was increased by 0·07 when Cool-Season Grasses were established by broadcasting. Amount of residue at sowing did not significantly affect herbage yield of Cool-Season grass, but increased residue in autumn resulted in a 0·16 increase in total herbage production in the year following sowing. Residue amount did not affect over-winter survival of grass seedlings, and productivity benefits of increased residue are small compared with reduced harvest arising from underutilization of warm-Season pasture residue in autumn.

Bingru Huang - One of the best experts on this subject based on the ideXlab platform.

  • involvement of antioxidants and lipid peroxidation in the adaptation of two Cool Season Grasses to localized drought stress
    Environmental and Experimental Botany, 2001
    Co-Authors: Jinmin Fu, Bingru Huang
    Abstract:

    Abstract In natural environments, drought often occurs in surface soil while water is available for plant uptake deeper in the soil profile. The objective of the study was to examine the involvement of antioxidant metabolism and lipid peroxidation in the responses of two Cool-Season Grasses to surface soil drying. Kentucky bluegrass ( Poa pratensis L) and tall fescue ( Festuca arundinacea Schreb.) were grown in split tubes, consisting of two sections (each 10 cm in diameter and 20 cm long). Grasses were subjected to three soil moisture regimes: (a) well-watered control: whole soil profile was watered; (b) surface drying: surface 20 cm of soil was dried by withholding irrigation and the lower 20 cm of soil was watered; (c) full drying: whole soil profile was dried. Surface drying had no effects on relative water content (RWC) and chlorophyll content (Chl) for both Grasses and only slightly reduced shoot growth for tall fescue. Superoxide dismutase (SOD) activity increased, while catalase (CAT) and peroxidase (POD) activities remained unchanged during most periods of surface drying. Malondialdehyde (MDA) content was unaffected by surface drying for tall fescue, but increased initially and then decreased to the control level for Kentucky bluegrass. Under full drying, RWC, Chl content, and shoot dry weight decreased, but MDA content increased in both Grasses; SOD and POD activities initially increased transiently and then decreased; CAT remained unchanged for 25 days and then decreased. These results suggested that both Kentucky bluegrass and tall fescue were capable of surviving surface soil drying. This capability could be related to increases in antioxidant activities, particularly SOD and CAT. However, full drying suppressed antioxidant activities and induced lipid peroxidation.

  • effects of calcium on antioxidant activities and water relations associated with heat tolerance in two Cool Season Grasses
    Journal of Experimental Botany, 2001
    Co-Authors: Yiwei Jiang, Bingru Huang
    Abstract:

    Calcium (Ca2+) may be involved in plant tolerance to heat stress by regulating antioxidant metabolism or/and water relations. This study was designed to examine whether external Ca2+ treatment would improve heat tolerance in two C(3), Cool-Season grass species, tall fescue (Festuca arundinacea L.) and Kentucky bluegrass (Poa pratensis L.), and to determine the physiological mechanisms of Ca2+ effects on grass tolerance to heat stress. Grasses were treated with CaCl(2) (10 mM) or H(2)O by foliar application and then exposed to heat stress (35/30 degrees C) in growth chambers. Some of the Ca2+ -untreated plants were maintained at 20/15 degrees C as the temperature control. Heat stress reduced grass quality, relative water content (RWC), and chlorophyll (Chl) content of leaves in both species, but Ca2+ treatment increased all three factors under heat stress. The Ca2+ concentration in cell saps increased with heat stress and with external Ca2+ treatment in both species. Osmotic potential increased with heat stress, but external Ca2+ treatment had no effect. Osmotic adjustment increased during short-term heat stress, but then decreased with a prolonged period of stress; it was not influenced by Ca2+ treatment. The activity of superoxide dismutase (SOD) in both species increased transiently at 12 d of heat stress and then remained at a level similar to that of the control. External Ca2+ treatment had no effect on SOD activity. The activities of catalase (CAT), ascorbate peroxidase (AP), and glutathione reductase (GR) of both species decreased during heat stress. Plants treated with Ca2+ under heat stress had higher CAT, GR and AP activities than untreated plants. Lesser amounts of malondialdehyde (MDA) accumulated in Ca2+ -treated plants than in untreated plants during extended periods of heat stress. The results suggested that exogenous Ca2+ treatment enhanced heat tolerance in both tall fescue and Kentucky bluegrass. This enhancement was related to the maintenance of antioxidant activities and a decrease in membrane lipid peroxidation, but not to the regulation of osmotic potential and osmotic adjustment.

  • Involvement of antioxidants and lipid peroxidation in the adaptation of two Cool-Season Grasses to localized drought stress
    Environmental and Experimental Botany, 2001
    Co-Authors: Jinmin Fu, Bingru Huang
    Abstract:

    In natural environments, drought often occurs in surface soil while water is available for plant uptake deeper in the soil profile. The objective of the study was to examine the involvement of antioxidant metabolism and lipid peroxidation in the responses of two Cool-Season Grasses to surface soil drying. Kentucky bluegrass (Poa pratensis L) and tall fescue (Festuca arundinacea Schreb.) were grown in split tubes, consisting of two sections (each 10 cm in diameter and 20 cm long). Grasses were subjected to three soil moisture regimes: (a) well-watered control: whole soil profile was watered; (b) surface drying: surface 20 cm of soil was dried by withholding irrigation and the lower 20 cm of soil was watered; (c) full drying: whole soil profile was dried. Surface drying had no effects on relative water content (RWC) and chlorophyll content (Chl) for both Grasses and only slightly reduced shoot growth for tall fescue. Superoxide dismutase (SOD) activity increased, while catalase (CAT) and peroxidase (POD) activities remained unchanged during most periods of surface drying. Malondialdehyde (MDA) content was unaffected by surface drying for tall fescue, but increased initially and then decreased to the control level for Kentucky bluegrass. Under full drying, RWC, Chl content, and shoot dry weight decreased, but MDA content increased in both Grasses; SOD and POD activities initially increased transiently and then decreased; CAT remained unchanged for 25 days and then decreased. These results suggested that both Kentucky bluegrass and tall fescue were capable of surviving surface soil drying. This capability could be related to increases in antioxidant activities, particularly SOD and CAT. However, full drying suppressed antioxidant activities and induced lipid peroxidation. © 2001 Elsevier Science B.V.