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Open AccessEditorial

Forage Plant Ecophysiology: A Discipline Come of Age

by Cory Matthew and Lilian Elgalise Techio Pereira

Agriculture 2017, 7(8), 63; https://doi.org/10.3390/agriculture7080063 - 27 Jul 2017

Cited by 1 | Viewed by 5446

Abstract

The first use of the term “ecology” is credited to German scientist Ernst Haekel in 1866, who used the word to describe the total science of relationships between organisms and their environment [1].[...] Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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943 KiB

Open AccessArticle

Do Phytomer Turnover Models of Plant Morphology Describe Perennial Ryegrass Root Data from Field Swards?

by Cory Matthew, Alec D. Mackay and Arif Hasan Khan Robin

Agriculture 2016, 6(3), 28; https://doi.org/10.3390/agriculture6030028 - 8 Jul 2016

Cited by 8 | Viewed by 6728

Abstract

This study aimed to elucidate seasonal dynamics of ryegrass root systems in field swards. Established field swards of perennial ryegrass with white clover removed by herbicide and fertilised with nitrogen (N) to replace clover N fixation were subjected to lax and hard grazing [...] Read more.

This study aimed to elucidate seasonal dynamics of ryegrass root systems in field swards. Established field swards of perennial ryegrass with white clover removed by herbicide and fertilised with nitrogen (N) to replace clover N fixation were subjected to lax and hard grazing management and root biomass deposition monitored using a root ingrowth core technique over a 13 month period. A previously published phytomer-based model of plant morphology that assumes continuous turnover of the root system was used to estimate mean individual root weight (mg) not previously available for field swards. The predicted root weights compared credibly with root data from hydroponic culture and the model output explained much of the seasonal variation in the field data. In particular, root deposition showed a seasonality consistent with influence of an architectural signal (AS) determined by plant morphology. This AS arises because it is theoretically expected that with rising temperatures and decreasing phyllochron in early summer, more than one leaf on average would feed each root bearing node. Conversely, in autumn the reverse would apply and root deposition is expected to be suppressed. The phytomer-based model was also able to explain deeper root penetration in summer dry conditions, as seen in the field data. A prediction of the model is that even though total root deposition is reduced by less than 10% under hard grazing, individual root weight is reduced proportionately more because the available substrate is being shared between a higher population of tillers. Two features of the field data not explained by the phytomer based model, and therefore suggestive of hormonal signaling, were peaks of root production after summer drought and in late winter that preceded associated herbage mass rises by about one month. In summary, this research supports a view that the root system of ryegrass is turning over on a continuous basis, like the leaves above ground. The phytomer based model was able to explain much of the seasonal variation in root deposition in field swards, and also predicts a shift of root deposition activity, deeper in summer and shallower in winter. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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256 KiB

Open AccessArticle

Growth Strategy of Rhizomatous and Non-Rhizomatous Tall Fescue Populations in Response to Defoliation

by Racheal H. Bryant, Cory Matthew and John Hodgson

Agriculture 2015, 5(3), 791-805; https://doi.org/10.3390/agriculture5030791 - 11 Sep 2015

Cited by 5 | Viewed by 6455

Abstract

The aim of this study was to determine the morphology of rhizome production, in two contrasting rhizomatous (R) and non-rhizomatous (NR) tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) populations, and to assess whether rhizome production is associated with changed biomass allocation or plant [...] Read more.

The aim of this study was to determine the morphology of rhizome production, in two contrasting rhizomatous (R) and non-rhizomatous (NR) tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) populations, and to assess whether rhizome production is associated with changed biomass allocation or plant growth pattern. Growth of R and NR populations was compared, under hard defoliation (H, 50 mm stubble), lax defoliation (L, 100 mm stubble), or without defoliation (U, uncut). Populations were cloned and grown in a glasshouse and defoliated every three weeks, with destructive harvests performed at 6, 12 and 18 weeks. R plants allocated more biomass to root and less to pseudostem than NR plants. Plant tiller numbers were greatly reduced by defoliation, and R and NR populations differed in leaf formation strategy. R plants had narrower leaves than NR, but their leaves were longer, because of greater leaf elongation duration. R plants were more plastic than NR plants in response to defoliation. Ultimately, biomass allocation to rhizomes did not differ between populations but R plants exhibited a subtle shift in distribution of internode length with a few longer internode segments typically located on secondary and tertiary tillers. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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328 KiB

Open AccessArticle

Temperature Impact on the Forage Quality of Two Wheat Cultivars with Contrasting Capacity to Accumulate Sugars

by Máximo Lorenzo, Silvia G. Assuero and Jorge A. Tognetti

Agriculture 2015, 5(3), 649-667; https://doi.org/10.3390/agriculture5030649 - 17 Aug 2015

Cited by 4 | Viewed by 6449

Abstract

Wheat is increasingly used as a dual-purpose crop (for forage and grain production) worldwide. Plants encounter low temperatures in winter, which commonly results in sugar accumulation. High sugar levels might have a positive impact on forage digestibility, but may also lead to an [...] Read more.

Wheat is increasingly used as a dual-purpose crop (for forage and grain production) worldwide. Plants encounter low temperatures in winter, which commonly results in sugar accumulation. High sugar levels might have a positive impact on forage digestibility, but may also lead to an increased risk of bloat. We hypothesized that cultivars with a lower capacity to accumulate sugars when grown under cold conditions may have a lower bloat risk than higher sugar-accumulating genotypes, without showing significantly lower forage digestibility. This possibility was studied using two wheat cultivars with contrasting sugar accumulation at low temperature. A series of experiments with contrasting temperatures were performed in controlled-temperature field enclosures (three experiments) and growth chambers (two experiments). Plants were grown at either cool (8.1 °C–9.3 °C) or warm (15.7 °C–16.5 °C) conditions in field enclosures, and at either 5 °C or 25 °C in growth chambers. An additional treatment consisted of transferring plants from cool to warm conditions in the field enclosures and from 5 °C to 25 °C in the growth chambers. The plants in the field enclosure experiments were exposed to higher irradiances (i.e., 30%–100%) than those in the growth chambers. Our results show that (i) low temperatures led to an increased hemicellulose content, in parallel with sugar accumulation; (ii) low temperatures produced negligible changes in in vitro dry matter digestibility while leading to a higher in vitro rumen gas production, especially in the higher sugar-accumulating cultivar; (iii) transferring plants from cool to warm conditions led to a sharp decrease in in vitro rumen gas production in both cultivars; and (iv) light intensity (in contrast to temperature) appeared to have a lower impact on forage quality. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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342 KiB

Open AccessArticle

Nutrient Composition, Forage Parameters, and Antioxidant Capacity of Alfalfa (Medicago sativa, L.) in Response to Saline Irrigation Water

by Jorge F. S. Ferreira, Monica V. Cornacchione, Xuan Liu and Donald L. Suarez

Agriculture 2015, 5(3), 577-597; https://doi.org/10.3390/agriculture5030577 - 28 Jul 2015

Cited by 55 | Viewed by 9056

Abstract

Although alfalfa is moderately tolerant of salinity, the effects of salinity on nutrient composition and forage parameters are poorly understood. In addition, there are no data on the effect of salinity on the antioxidant capacity of alfalfa. We evaluated four non-dormant, salinity-tolerant commercial [...] Read more.

Although alfalfa is moderately tolerant of salinity, the effects of salinity on nutrient composition and forage parameters are poorly understood. In addition, there are no data on the effect of salinity on the antioxidant capacity of alfalfa. We evaluated four non-dormant, salinity-tolerant commercial cultivars, irrigated with saline water with electrical conductivities of 3.1, 7.2, 12.7, 18.4, 24.0, and 30.0 dS·m⁻¹, designed to simulate drainage waters from the California Central Valley. Alfalfa shoots were evaluated for nutrient composition, forage parameters, and antioxidant capacity. Salinity significantly increased shoot N, P, Mg, and S, but decreased Ca and K. Alfalfa micronutrients were also affected by salinity, but to a lesser extent. Na and Cl increased significantly with increasing salinity. Salinity slightly improved forage parameters by significantly increasing crude protein, the net energy of lactation, and the relative feed value. All cultivars maintained their antioxidant capacity regardless of salinity level. The results indicate that alfalfa can tolerate moderate to high salinity while maintaining nutrient composition, antioxidant capacity, and slightly improved forage parameters, thus meeting the standards required for dairy cattle feed. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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309 KiB

Open AccessArticle

A Modified Thermal Time Model Quantifying Germination Response to Temperature for C₃ and C₄ Species in Temperate Grassland

by Hongxiang Zhang, Yu Tian and Daowei Zhou

Agriculture 2015, 5(3), 412-426; https://doi.org/10.3390/agriculture5030412 - 6 Jul 2015

Cited by 10 | Viewed by 6514

Abstract

Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C₄ and 15 C₃ species [...] Read more.

Thermal-based germination models are widely used to predict germination rate and germination timing of plants. However, comparison of model parameters between large numbers of species is rare. In this study, seeds of 27 species including 12 C₄ and 15 C₃ species were germinated at a range of constant temperatures from 5 °C to 40 °C. We used a modified thermal time model to calculate germination parameters at suboptimal temperatures. Generally, the optimal germination temperature was higher for C₄ species than for C₃ species. The thermal time constant for the 50% germination percentile was significantly higher for C₃ than C₄ species. The thermal time constant of perennials was significantly higher than that of annuals. However, differences in base temperatures were not significant between C₃ and C₄, or annuals and perennial species. The relationship between germination rate and seed mass depended on plant functional type and temperature, while the base temperature and thermal time constant of C₃ and C₄ species exhibited no significant relationship with seed mass. The results illustrate differences in germination characteristics between C₃ and C₄ species. Seed mass does not affect germination parameters, plant life cycle matters, however. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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530 KiB

Open AccessArticle

Variation in Response to Moisture Stress of Young Plants of Interspecific Hybrids between White Clover (T. repens L.) and Caucasian Clover (T. ambiguum M. Bieb.)

by Athole H. Marshall, Matthew Lowe and Rosemary P. Collins

Agriculture 2015, 5(2), 353-366; https://doi.org/10.3390/agriculture5020353 - 19 Jun 2015

Cited by 10 | Viewed by 5962

Abstract

Backcross hybrids between the important forage legume white clover (Trifolium repens L.), which is stoloniferous, and the related rhizomatous species Caucasian clover (T. ambiguum M. Bieb), have been produced using white clover as the recurrent parent. The effect of drought on [...] Read more.

Backcross hybrids between the important forage legume white clover (Trifolium repens L.), which is stoloniferous, and the related rhizomatous species Caucasian clover (T. ambiguum M. Bieb), have been produced using white clover as the recurrent parent. The effect of drought on the parental species and two generations of backcrosses were studied in a short-term glasshouse experiment under three intensities of drought. Plants of Caucasian clover maintained a higher leaf relative water content and leaf water potential than white clover at comparable levels of drought, with the response of the backcrosses generally intermediate between the parents. Severe drought significantly reduced stolon growth rate and leaf development rate of white clover compared to the control, well-watered treatment, whilst differences between these two treatments in the backcross hybrids were relatively small. The differences between parental species and the backcrosses in root morphology were studied in 1m long vertical pipes. The parental species differed in root weight distribution, with root weight of Caucasian clover significantly greater than white clover in the 0.1 m to 0.5 m root zone. The backcrosses exhibited root characteristics intermediate between the parents. The extent to which these differences influence the capacity to tolerate drought is discussed. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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1630 KiB

Open AccessArticle

Linking Management, Environment and Morphogenetic and Structural Components of a Sward for Simulating Tiller Density Dynamics in Bahiagrass (Paspalum notatum)

by Masahiko Hirata

Agriculture 2015, 5(2), 330-343; https://doi.org/10.3390/agriculture5020330 - 17 Jun 2015

Cited by 5 | Viewed by 6343

Abstract

A model which describes tiller density dynamics in bahiagrass (Paspalum notatum Flügge) swards has been developed. The model incorporates interrelationships between various morphogenetic and structural components of the sward and uses the inverse of the self-thinning rule as the standard relationship between [...] Read more.

A model which describes tiller density dynamics in bahiagrass (Paspalum notatum Flügge) swards has been developed. The model incorporates interrelationships between various morphogenetic and structural components of the sward and uses the inverse of the self-thinning rule as the standard relationship between tiller density and tiller weight (a density-size equilibrium) toward which tiller density progressively changes over time under varying nitrogen (N) rates, air temperature and season. Water and nutrient limitations were not considered except partial consideration of N. The model was calibrated against data from swards subjected to different N rates and cutting intensities, and further validated against data from a grazed sward and swards under different cutting intensities. As the calibration and validation results were satisfactory, the model was used as a tool to investigate the responses of tiller density to various combinations of defoliation frequencies and intensities. Simulations identified defoliation regimes required for stabilizing tiller density at an arbitrary target level, i.e., sustainable use of the sward. For example, the model predicted that tiller density can be maintained at a medium level of about 4000 m⁻² under conditions ranging from weekly cuttings to an 8 cm height to 8-weekly cuttings to 4 cm. More intense defoliation is needed for higher target tiller density and vice versa. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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Review

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784 KiB

Open AccessReview

Using Ecophysiology to Improve Farm Efficiency: Application in Temperate Dairy Grazing Systems

by David F. Chapman

Agriculture 2016, 6(2), 17; https://doi.org/10.3390/agriculture6020017 - 18 Apr 2016

Cited by 24 | Viewed by 7230

Abstract

Information on the physiological ecology of grass-dominant pastures has made a substantial contribution to the development of practices that optimise the amount of feed harvested by grazing animals in temperate livestock systems. However, the contribution of ecophysiology is often under-stated, and the need [...] Read more.

Information on the physiological ecology of grass-dominant pastures has made a substantial contribution to the development of practices that optimise the amount of feed harvested by grazing animals in temperate livestock systems. However, the contribution of ecophysiology is often under-stated, and the need for further research in this field is sometimes questioned. The challenge for ecophysiolgists, therefore, is to demonstrate how ecophysiological knowledge can help solve significant problems looming for grassland farming in temperate regions while also removing constraints to improved productivity from grazed pastures. To do this, ecophysiological research needs to align more closely with related disciplines, particularly genetics/genomics, agronomy, and farming systems, including systems modelling. This review considers how ecophysiological information has contributed to the development of grazing management practices in the New Zealand dairy industry, an industry that is generally regarded as a world leader in the efficiency with which pasture is grown and utilised for animal production. Even so, there are clear opportunities for further gains in pasture utilisation through the refinement of grazing management practices and the harnessing of those practices to improved pasture plant cultivars with phenotypes that facilitate greater grazing efficiency. Meanwhile, sub-optimal persistence of new pastures continues to constrain productivity in some environments. The underlying plant and population processes associated with this have not been clearly defined. Ecophysiological information, placed in the context of trait identification, grounded in well-designed agronomic studies and linked to plant improvements programmes, is required to address this. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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Open AccessReview

Defoliation, Shoot Plasticity, Sward Structure and Herbage Utilization in Pasture: Review of the Underlying Ecophysiological Processes

by François Gastal and Gilles Lemaire

Agriculture 2015, 5(4), 1146-1171; https://doi.org/10.3390/agriculture5041146 - 25 Nov 2015

Cited by 94 | Viewed by 14587

Abstract

Sward structure affects herbage growth, pasture species dynamics, and herbage utilization. Defoliation management has a major impact on sward structure. In particular, tiller size-tiller density compensations allow for the maintenance of herbage growth. Tiller size and tiller density are determined by several major [...] Read more.

Sward structure affects herbage growth, pasture species dynamics, and herbage utilization. Defoliation management has a major impact on sward structure. In particular, tiller size-tiller density compensations allow for the maintenance of herbage growth. Tiller size and tiller density are determined by several major morphogenetical components. Defoliation affects these morphogenetical components, depending on its frequency and its intensity, through several direct and indirect physiological and environmental processes. Due to the implications of leaf area removal, defoliation has a direct effect on the mobilization of C and N reserves and their supply to growing leaves. In addition, defoliation has an indirect effect on leaf and tiller morphogenesis, due to its impact on the light environment within the canopy as well as plant responses to light signals (blue light, red far red ratio). Defoliation may also in some cases have a direct negative effect on leaf growth by damaging leaf meristems. Understanding the respective role of these various physiological and environmental processes requires studies where defoliation, photosynthetic active radiation and light signals are manipulated independently. Past and recent knowledge on these direct and indirect effects of defoliation on plant morphogenesis are discussed, leading to an overall integrated view of physiological and environmental processes that lead to adaptations of sward structure in response to defoliation management. Major consequences for herbage utilization efficiency are presented. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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283 KiB

Open AccessReview

Carbon Assimilation, Biomass Partitioning and Productivity in Grasses

by Louis J. Irving

Agriculture 2015, 5(4), 1116-1134; https://doi.org/10.3390/agriculture5041116 - 10 Nov 2015

Cited by 66 | Viewed by 11076

Abstract

Plant growth correlates with net carbon gain on a whole plant basis. Over the last several decades, the driving factors shaping plant morphology and performance have become increasingly clear. This review seeks to explore the importance of these factors for grass performance. Briefly, [...] Read more.

Plant growth correlates with net carbon gain on a whole plant basis. Over the last several decades, the driving factors shaping plant morphology and performance have become increasingly clear. This review seeks to explore the importance of these factors for grass performance. Briefly, these fall into factors influencing photosynthetic rates directly, competition between plants in a canopy, and nutrient status and availability. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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852 KiB

Open AccessReview

Leaf Length Variation in Perennial Forage Grasses

by Philippe Barre, Lesley B. Turner and Abraham J. Escobar-Gutiérrez

Agriculture 2015, 5(3), 682-696; https://doi.org/10.3390/agriculture5030682 - 25 Aug 2015

Cited by 22 | Viewed by 9647

Abstract

Leaf length is a key factor in the economic value of different grass species and cultivars in forage production. It is also important for the survival of individual plants within a sward. The objective of this paper is to discuss the basis of [...] Read more.

Leaf length is a key factor in the economic value of different grass species and cultivars in forage production. It is also important for the survival of individual plants within a sward. The objective of this paper is to discuss the basis of within-species variation in leaf length. Selection for leaf length has been highly efficient, with moderate to high narrow sense heritability. Nevertheless, the genetic regulation of leaf length is complex because it involves many genes with small individual effects. This could explain the low stability of QTL found in different studies. Leaf length has a strong response to environmental conditions. However, when significant genotype × environment interactions have been identified, their effects have been smaller than the main effects. Recent modelling-based research suggests that many of the reported environmental effects on leaf length and genotype × environment interactions could be biased. Indeed, it has been shown that leaf length is an emergent property strongly affected by the architectural state of the plant during significant periods prior to leaf emergence. This approach could lead to improved understanding of the factors affecting leaf length, as well as better estimates of the main genetic effects. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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4792 KiB

Open AccessReview

Ecophysiology of C₄ Forage Grasses—Understanding Plant Growth for Optimising Their Use and Management

by Sila Carneiro Da Silva, André Fischer Sbrissia and Lilian Elgalise Techio Pereira

Agriculture 2015, 5(3), 598-625; https://doi.org/10.3390/agriculture5030598 - 29 Jul 2015

Cited by 138 | Viewed by 15142

Abstract

Grazing management has been the focus of the research with forage plants in Brazil for many years. Only in the last two decades, however, significant changes and advances have occurred regarding the understanding of the key factors and processes that determine adequate use [...] Read more.

Grazing management has been the focus of the research with forage plants in Brazil for many years. Only in the last two decades, however, significant changes and advances have occurred regarding the understanding of the key factors and processes that determine adequate use of tropical forage plants in pastures. The objective of this review is to provide an historical overview of the research with forage plants and grasslands in Brazil, highlighting advances, trends, and results, as well as to describe the current state of the art and identify future perspectives and challenges. The information is presented in a systematic manner, favoring an integrated view of the different trends and research philosophies. A critical appraisal is given of the need for revision and change of paradigms as a means of improving and consolidating the knowledge on animal production from pastures. Such analysis idealizes efficient, sound and sustainable grazing management practices necessary to realize the existing potential for animal production in the tropics. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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374 KiB

Open AccessReview

Beneficial Effects of Temperate Forage Legumes that Contain Condensed Tannins

by Jennifer W. MacAdam and Juan J. Villalba

Agriculture 2015, 5(3), 475-491; https://doi.org/10.3390/agriculture5030475 - 20 Jul 2015

Cited by 46 | Viewed by 9450

Abstract

The two temperate forage legumes containing condensed tannins (CT) that promote ruminant production are birdsfoot trefoil (Lotus corniculatus L.; BFT) and sainfoin (Onobrychis viciifolia Scop.; SF). Both are well-adapted to the cool-temperate climate and alkaline soils of the Mountain West USA. [...] Read more.

The two temperate forage legumes containing condensed tannins (CT) that promote ruminant production are birdsfoot trefoil (Lotus corniculatus L.; BFT) and sainfoin (Onobrychis viciifolia Scop.; SF). Both are well-adapted to the cool-temperate climate and alkaline soils of the Mountain West USA. Condensed tannins comprise a diverse family of bioactive chemicals with multiple beneficial functions for ruminants, including suppression of internal parasites and enteric methane. Birdsfoot trefoil contains 10 to 40 g·CT·kg⁻¹ dry matter (DM), while SF contains 30 to 80 g·CT·kg⁻¹ DM. Our studies have focused on these two plant species and have demonstrated consistently elevated rates of gain for beef calves grazing both BFT and SF. Novel results from our BFT research include carcass dressing percentages and consumer sensory evaluations equivalent to feedlot-finished steers and significantly greater than grass-finished steers, but with omega-3 fatty acid concentrations equal to grass-finished beef. We have further demonstrated that ruminants fed BFT or SF will consume more endophyte-infected tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) forage or seed than ruminants fed a non-CT forage legume. There is great potential value for sustainable livestock production in the use of highly digestible, nitrogen-fixing legumes containing tannins demonstrated to improve ruminant productivity. Full article

(This article belongs to the Special Issue Forage Plant Ecophysiology)

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