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Articles 301 - 330 of 16610

Full-Text Articles in Physical Sciences and Mathematics

Plant List Of Accepted Nomenclature, Taxonomy And Symbols, J S. Peterson Aug 2024

Plant List Of Accepted Nomenclature, Taxonomy And Symbols, J S. Peterson

IGC Proceedings (1993-2023)

The Plant List of Accepted Nomenclature, Taxonomy & Symbols (PLANTS) is a dynamic database providing scientific and vernacular names, distributional, growth form, origin, symbols and bibliographic standardised botanical data to US federal agencies. PLANTS encompasses the vascular plant, moss, lichen and liverwort flora of North America, north of the Mexico border, including US states and territories.


The C3 Plants And C4 Plants Growing On Semi-Arid Steppes Of North-East China, Yin Lijuan, Zhu Tingcheng Aug 2024

The C3 Plants And C4 Plants Growing On Semi-Arid Steppes Of North-East China, Yin Lijuan, Zhu Tingcheng

IGC Proceedings (1993-2023)

The north-east steppe of China is semi-arid. Forty-seven species of C3 plants and 53 species of C4 plants were defined. The C pathway of the 42 forage species among the total l 00 species is firstly identified by determining the ratio between RuBPCase/PEPCase (RIP) and observing the Kranz leaf anatomy. The abundance of C4 plants decreases with decreasing precipitation and the intensity of soil sandesation, and increases with lower latitude and increased soil salinisation.


Indigenous Populations Of Lolium Perenne L. Identification, Evaluation And Conservation, G Spatz, A Oetmann, C Paul Aug 2024

Indigenous Populations Of Lolium Perenne L. Identification, Evaluation And Conservation, G Spatz, A Oetmann, C Paul

IGC Proceedings (1993-2023)

One hundred indigenous ryegrass populations were identified along 2 geographical gradients in Germany (west-east and north-south), Each population was sampled by collecting 180 tillers in 1991. The total 18 000 tillers were cultivated and will be examined as spaced plants (ex situ) in 1992 Nine selected populations were investigated in situ 1991. The results of the i11 situ investigations show high variability between and within the populations. The most valuable populations will be conserved as gene reserves within their environments (i11 situ). Promising material will in future be handed over to private breeders.


A Study On The Promising Ecotypes Of Secale Montaanum Guss., Bahram Peymani-Fard Aug 2024

A Study On The Promising Ecotypes Of Secale Montaanum Guss., Bahram Peymani-Fard

IGC Proceedings (1993-2023)

Secale montamum (mountain rye) has been identified as a well-adapted species for rehabilitation of the substeppic rangelands of Iran. Further investigation on the quality and quantity values of different ecotypes of this species was required. The main objective of this study was to determine phenological stages, herbage yield and protein percentage of the promising native ecotypes of Secale montanum. This research was conducted on 7 ecotypes in which early growth started in late April and heading occurred in late May. Comparison of the 4-year total herbage yield indicated significant differences among the ecotypes, Secale momtanum (10091), which was the previously …


Breeding Systems Of Several Vicia Species, J A. Mosjidis, X Zhang Aug 2024

Breeding Systems Of Several Vicia Species, J A. Mosjidis, X Zhang

IGC Proceedings (1993-2023)

Lack of or limited knowledge of 1he breeding systems of most of the Vicia speci1;s in the National Plant Germplasm System (USA) makes difficult the regeneration of the accessions as well as the maintenance of their genetic variability. Twenty-three accessions of V. arliculata, V. benghalensis, V. cracca, V. ervilia, V. lutea, V. narbonensis, V. pamionica and V. villosa were grown in the field in 1989 and 1990. Some plants were left uncovered outside"cages until fully mature while others were enclosed in cages when the first flower buds appeared. Plowers of the plants placed inside cages were subjected to the following …


Forage Quality Determinants Of Mott Elephantgrass And Pennisetum Hybrids, L E. Sollenberger, J E. Moore, J A. Flores-C, C J. Chaparro, B Macoon Aug 2024

Forage Quality Determinants Of Mott Elephantgrass And Pennisetum Hybrids, L E. Sollenberger, J E. Moore, J A. Flores-C, C J. Chaparro, B Macoon

IGC Proceedings (1993-2023)

Daily gains of cattle grazing Mott elephantgrass (MB; Pennisteum purpureIum Schum.) arc approximately twice those obtained on other warm-season perennial grasses grown in Florida, USA, but plant characteristics responsible for the high forage quality of MB have not been identified. Three experiments were conducted during 1987- 1991 to determine factors that explain the high forage quality of MB and to assess the quality potential of P. purpureum x P. glaucum (L.) [R.Br.J x clephantgrass hybrids. Higher organic matter (OM) digestibility and intake of MB than Pensacola bahiagrass (PB; Paspalum nonatum Flugge) were associated with a lesser percentage of sclercnchyma (1.6 …


Characterisation Of Us Collection Of Clover And Special Purpose Legume Germplasm, R R. Smith, K H. Quesenberry Aug 2024

Characterisation Of Us Collection Of Clover And Special Purpose Legume Germplasm, R R. Smith, K H. Quesenberry

IGC Proceedings (1993-2023)

Systematic collection of forage legume germplasm by the USA from the centers of origin was initiated in the 1890s. Since then over 11 000 accessions of clover and special-purpose legume species have been introduced into the US. These accessions are catalogued and maintained by the National Plant Germplasm System with working collections located at 4 locations in the US. Appropriate passport and evaluation data are available in the US Germplasm Resources Information Network (GRIN). The Clover and Special Purpose Legume Crop Advisory Commitlee is responsible for providing advice to the National Plant Germplasm System on the collection, mnintenance, evaluation and …


Determination Of Extractable And Bound Condensed Tannins In Forage Species, G B. Douglas, P Donkers, A G. Foote, T N. Barry Aug 2024

Determination Of Extractable And Bound Condensed Tannins In Forage Species, G B. Douglas, P Donkers, A G. Foote, T N. Barry

IGC Proceedings (1993-2023)

The levels of condensed tannins (CT) in 12 herbaceous species growing at 2 sites were determined using a recently modified butanol­HCL procedure. The method measured CT extractable in 70:30 acetone: water, and CT bound to protein and fibre, using ground, freeze-dried material. Total plant CT levels ranged from trace to 8% OM, with high concentrations (5-8% DM) being detected in 3 Dorycnium spp. and Lotus pedunculatus. Coronilla varia, Hedysarum coronarium and Lotus corniculatus had CT levels of 2-4% DM which may be appropriate for optimum nutritional value. CT content in ·n. rect11m, D. pe11taphyl/11m and L. pedunculatus was higher …


Herbaceous And Shrub Legumes Of Queensland: A Resource For Forage And Crop Improvement, J B. Hacker Aug 2024

Herbaceous And Shrub Legumes Of Queensland: A Resource For Forage And Crop Improvement, J B. Hacker

IGC Proceedings (1993-2023)

The potential for pasture or crop improvement of legume species native to Queensland, Australia is discussed. The most promising genera are Cajanus, Desmodlum, Glycine, Psoralea, Sesbanla and Vigna. Genera endemic to Australia offer little immediate scope for use in pasture or crop improvement. Some species, particularly in the genera Acacia, Crotalaria, Gastroloblum, Indigofera and Neptunia, can be toxic to livestock.


Morphological Characterization Of Brachiaria Germplasm, C B. Valle, B L. Maass, C B. Almeida, J.C G. Costa Aug 2024

Morphological Characterization Of Brachiaria Germplasm, C B. Valle, B L. Maass, C B. Almeida, J.C G. Costa

IGC Proceedings (1993-2023)

Brachiaria is a grass genus native to the tropical savannas of Africa. It encompasses about 90 species, a: few of which have gained economic importance owing to their adaptation to acid soils. A study was conducted at Campo Grande, Brazil and Quilichao, Colombia, using a large Brachiaria collection assembled by CIAT in east Africa. The objectives were to describe the diversity of this germplasm and to classify the accessions in clusters based on 7 morphological characters, by applying numerical taxonomy. Principal Component and Cluster Analyses were used. Wide variation was observed among the 386 accessions of 13 different species in …


Potential Of European Perennial Ryegrass Germplasm In Southern New Zealand, K H. Widdup, D L. Ryan Aug 2024

Potential Of European Perennial Ryegrass Germplasm In Southern New Zealand, K H. Widdup, D L. Ryan

IGC Proceedings (1993-2023)

86 cullivars of perennial ryegrass from The Netherlands, Germany, Denmark, France and Britain together with 9 New Zealand (NZ) cultivars were evaluated for agronomic potential in the cool, temperate southern region of NZ. Spaced plants of each cultivar were established in 1989 and screened for seasonal growth, moiphological features, head emergence, foliar diseases and endophyte presence. Principal Component Analysis (PCA) was used to order the relative performance of the cultivars taking all characters into consideration. A group containing 5 elite tetraploid and 10 diploid European cultivars showed potential for improving the summer feed quality of ryegrass. These cultivars contained densely …


A Landino White Clover Breeding Programme In Northern Italy, P Annicchiarico, E Piano Aug 2024

A Landino White Clover Breeding Programme In Northern Italy, P Annicchiarico, E Piano

IGC Proceedings (1993-2023)

Ladino wh ite clover (Trifolium repens L.) has traditionally been grown in pure stand rotational meadows throughout the Po Valley. Recent changes in the farming systems have drastically reduced the presence of this clover. Its rehabilitation depends on the cultivation of new, more productive cultivars in association with a grass. Thirty­two ecotypes including both farm land races and natural populations were collected and evaluated for dry mailer yield (OM) and seed yield, Significant variability was found among these materials for both traits. Compared with natural populations, land races yielded far more seed and as much DM . Some aspects …


Screening Trifolium Repens L. And T. Pratense L. Germplasm For Resistance To Cylindrocladium Crotalariae (Loos) Bell & Sobers, D S. Wofford, K H. Quesenberry Aug 2024

Screening Trifolium Repens L. And T. Pratense L. Germplasm For Resistance To Cylindrocladium Crotalariae (Loos) Bell & Sobers, D S. Wofford, K H. Quesenberry

IGC Proceedings (1993-2023)

Using a greenhouse screening technique, 200 plant introduction Jines of white clover (Trifolium repens L.) and red clover (T. pratense L.) germplasm were evaluated for resistance to cylindrocladium root rot incited by Cyl/11drocladium crotalariae (Loos) Bell & Sobers. In general, white clover germplasm had much higher levels of resistance than red clover. Over 60% of white clover introductions had 30% or greater resistance to cylindrocladium root rot, with 21 % of the lines possessing more than 40% resistant plants. No relationship was found between level of resistance and geographic origin for white clover. Red clover was more susceptible to …


Domestication Of The Australian Perennial Native Grass, Microlaena Stipoides, R.D B. Whalley, C.H A. Huxtable Aug 2024

Domestication Of The Australian Perennial Native Grass, Microlaena Stipoides, R.D B. Whalley, C.H A. Huxtable

IGC Proceedings (1993-2023)

Microlaena stipoides (Labill.) R.Br. is a year-long green perennial grass which is common throughout eastern and southern Australia. This species is a valuable component of pastures in parts of the New South Wales Tablelands because of its tolerance of acid soils and its ability to survive recent droughts.


Contribution Of Undomesticated Germplasm To Development Of Persistent, Grazing-Tolerant Lucerne, I Kaehne, E T. Kobelt, J A. Horsenell Aug 2024

Contribution Of Undomesticated Germplasm To Development Of Persistent, Grazing-Tolerant Lucerne, I Kaehne, E T. Kobelt, J A. Horsenell

IGC Proceedings (1993-2023)

The development of lucerne (Medicago saliva L.) germplasms which are tolerant to continuous grazing, adapted to dryland agriculture in the mediterranean zone and resistant to aphids, is described, Undomesticated lucerne accessions from 14 countries were crossed with winter-active cultivated lucerne accessions adapted to mediterranean climates to produce 4 S populations which were selected for tolerance to continuous intense grazing by sheep, The most tolerant populations were screened to develop germplasms resistant to spotted alfalfa aphid and blue-green aphid. The 72 populations that were developed from these germplasms by further selection for grazing tolerance and aphid resistance were tested for …


Multilocational Testing Of Grasses And Legumes In The Humid Tropics Of South America, G Keller-Grein, M C. Amezquita, G Lema, L H. Franco Aug 2024

Multilocational Testing Of Grasses And Legumes In The Humid Tropics Of South America, G Keller-Grein, M C. Amezquita, G Lema, L H. Franco

IGC Proceedings (1993-2023)

Adaptability of 5 grass and 13 legume accessions tested in 34 regional agronomic trials throughout the South American humid tropics was assessed by conducting a multilocational analysis on seasonal dry matter (DM) yield at 12 weeks regrowth. Among legumes, Stylosamhes guianensis CIAT 184 and 136, Desmodium ovaifolum CIAT 350, Zornia latifolla CIAT 728 and Centrosema macrocarpum CIAT 5065 were the highest yielding accessions in both rainfall periods and showed high adaptability to environmental conditions. Centrosema brasllianan CIAT 5234, C. pubescence CIAT 438 and Desmodiun heterophyifom CIAT 349 had low productivity and low adaptability. For grasses, Andropogon gayanus CIAT 621 outyielded …


Germplasm Collecting By Iger: The Future, N R. Sackville Hamilton, K H. Chorlton, I D. Thomas, M D. Hayward Aug 2024

Germplasm Collecting By Iger: The Future, N R. Sackville Hamilton, K H. Chorlton, I D. Thomas, M D. Hayward

IGC Proceedings (1993-2023)

This paper will present novel approaches being implemented or planned lo improve future collections for forage germplasm, and to deal with changing priorities, with particular reference to Lolium perenne. With a large number of accessions already in the gene bank and providing a wide range of genes for possible utilisation, future collections must be targeted ever more precisely, The principle object is to acquire novel genes not already present in the gene bank, to maximise the proportion of genes in the gene pool of L. perenne that is held in the gene bank. A subsidiary object, to support not …


Phenotypic Variability For Morphological And Agronomic Traits In Atriplex And Medicago Shrubs Accessions, M Pasquale, L Nicola Aug 2024

Phenotypic Variability For Morphological And Agronomic Traits In Atriplex And Medicago Shrubs Accessions, M Pasquale, L Nicola

IGC Proceedings (1993-2023)

The phenotypic variability for morphological and biological traits in 139 accessions of Atriplex hallmus L. and in 54 of Medicago arborea L. were evaluated. The accessions were collected from Meditenanean locations. Accessions of Atriplex were evaluated for 3 cuts (winter, spring and summer) and Medicago for 2 (winter and spring). The variability in both species was remarkable for all traits examined: In Alrlplex accessions it was related to the different origin of the materials (Sardinian and other Mediterranean environments),


Germplasm Collection, Evaluation And Selection Of Naturalized Medicago Polymorpha In The Mediterranean Zone Of Chile, C Ovalle, J Avendano, A Del Pozo, D Crespo Aug 2024

Germplasm Collection, Evaluation And Selection Of Naturalized Medicago Polymorpha In The Mediterranean Zone Of Chile, C Ovalle, J Avendano, A Del Pozo, D Crespo

IGC Proceedings (1993-2023)

An introduction and evaluation programme is described that thus far includes 53 accessions of the naturalised annual medic Medicago polymorplia L. collected along a 1000 km N-S gradient in central. Chile and subsequently grown together in a common environment· selection trial together with 5 accessions received from International Center for Agricultural Research in the Dry Areas (!CARDA). Major selection criteria include: precocious phenology, spineless pods and hardseededness, and tolerance to acid soils. Onset of flowering was 82-127 day_s, later flowering being closely correlated with higher latitudes. Soil pH was 5.3-7 .5 in collection sites, and phosphorus levels were > 10 ppm …


Alfalfa Energetic Value Improvement For Dairy Cows, M Ghesquiere, Jean Claude Emile, G Genier, P Guy Aug 2024

Alfalfa Energetic Value Improvement For Dairy Cows, M Ghesquiere, Jean Claude Emile, G Genier, P Guy

IGC Proceedings (1993-2023)

An experimental alfalfa (Medicago saliva L.) population whose in vitro and in vivo digestibilities are significantly higher than controls was offered to dairy cows in order to investigate its efficiency for· feeding high yielding dairy cattle. Three trials were conducted on first or second cut. Alfalfa was given ad lib. and as fresh forage. The improved digestibility was confirmed. The experimental type was ingested more by cows despite a lower dry matter content and allowed higher milk production. This result shows a real genetic variability for energetic value in alfalfa.


Improving Methods Of Selecting Tropical Germplasm For Plant Breeding And Species Evaluation Studies, B C. Pengelly, R J. Williams Aug 2024

Improving Methods Of Selecting Tropical Germplasm For Plant Breeding And Species Evaluation Studies, B C. Pengelly, R J. Williams

IGC Proceedings (1993-2023)

Tropical forage germplasm centres have now accumulated very large collections of grass and legume species. The current methods of selecting germplasm from these collections, however, are based on limited information and tend to restrict the total germplasm pool from which selections can be made. To improve the selection process, genetic resource centres need to develop research programmes which both improve our understanding of the relative importance of particular plant attributes and the diversity of these attributes within collections.


Variability In Plant Morphology And Seed Production Of Sardinian Germplasm Of Burr Medic (Medicago Polymorpha L.), C Porqueddu, A Loi, F Veronesi Aug 2024

Variability In Plant Morphology And Seed Production Of Sardinian Germplasm Of Burr Medic (Medicago Polymorpha L.), C Porqueddu, A Loi, F Veronesi

IGC Proceedings (1993-2023)

A germplasm collection was undertaken in Sardinia (Italy) to study the ecology and distribution of burr medic to obtain genetic material to start a breeding programme. Burr medic was found at 0-1000 m (asl), in all types of soil with a pH between 5 and 8,5, Most populations were classified as var. v11lgarls Shin., but a few of them were polymorpha and brevbpl11a Heyn, The morphological characteristics of the plants, pods and seed showed a height variability between populations, The average number of pods per plant was 331 (min. 40 - max. 599), average number of seeds in each pod …


Use Of Ecogeographical Factors For Sampling A Core Collection Of Perennial Ryegrass, F Balfourier, G Charmet, C Grand-Ravel Aug 2024

Use Of Ecogeographical Factors For Sampling A Core Collection Of Perennial Ryegrass, F Balfourier, G Charmet, C Grand-Ravel

IGC Proceedings (1993-2023)

In order to set up a core collection of wild populations of pei:ennial ryegra11 {Lolium perenne L.), 3 different criteria have been combined lo make a choice of populations: similarities between populations, geographic location and ecological characteristics of their original sites. Different multivariate analysis and clustering methods, introducing a geographic contiguity CXJnstnint were used to sample, among a set of 550 Prench wild populations, 114 populations 111 representative as po11ible of the whole variability.


Lolium Canariense: An Endemic Ryegrass From Canary Islands, J A. Oliveira, G Charmet, F Balfourier, C Ravel Aug 2024

Lolium Canariense: An Endemic Ryegrass From Canary Islands, J A. Oliveira, G Charmet, F Balfourier, C Ravel

IGC Proceedings (1993-2023)

The taxonomic position of the endemic Lolium canariense within the genus Lolium has been Investigated by starch gel electrophoresis of 7 isozyme loci. Preliminary results show that L. canariense is preferentially autogamous, with an outcrossing rate of 0.08-0.16. II displays an average gene diversity of intermediate value between that of the strict inbreeder L. persicum and those of the outbreeders L. perenne, L. multiflorum and L. rlgidum. The hierarchical clustering from Nei's genetic distance (Genelics 1978) suggests that L. canariense is clearly differentiated from the group of outbreeding species


The Genera Vicia And Lathyrus In Rio Grande Do Sul (Southern Brazil): Cytogenetic And Isozymic Evaluation As Support For Plant Breeding, M T. Schifino-Wittmann, L H. Cardoso De Freitas, A H. Lau Aug 2024

The Genera Vicia And Lathyrus In Rio Grande Do Sul (Southern Brazil): Cytogenetic And Isozymic Evaluation As Support For Plant Breeding, M T. Schifino-Wittmann, L H. Cardoso De Freitas, A H. Lau

IGC Proceedings (1993-2023)

Native, naturalized and exotic Vicia and l.atliyrus species of Rio Grande do Sul were studied for chromosome numbers and meiotic behaviour, All species were diploid, with essentially regular meiosis and high pollen stainability. Interspecific differences for chiasma frequencies, chromosome and pollen grain size were detected. Polymorphism for chromosome number was observed in Vicia anguslilolia (2n = 10, 12, 14). Bsterase isozyme patterns are being analysed,


Evaluation Of Ecotypes Of Birdsfoot Trefoil (Lotus Cornicultaus L.) And Marsh Birdsfoot Trefoil (Lotus Uliginosus Schk.), K Mlynarczyk, L Olesinski Aug 2024

Evaluation Of Ecotypes Of Birdsfoot Trefoil (Lotus Cornicultaus L.) And Marsh Birdsfoot Trefoil (Lotus Uliginosus Schk.), K Mlynarczyk, L Olesinski

IGC Proceedings (1993-2023)

Ninety-seven ecotypes of birdsfoot trefoil and 75 of marsh birdsfoot trefoil were collected at Olsztyn-Kortowo (north-east Poland). In the years 1987-1991 some morphological and phenological characters of the collected natural populations were examined. The results showed the high differentiation in plant habit, flowering period, thousand­seed weight and number of seeds per pod.


Collection Of Native Forage Legume Germplasm In Vietnam, Rainer Schultze-Kraft, Ha Dinh Tuan, Nguyen Phung Ha Aug 2024

Collection Of Native Forage Legume Germplasm In Vietnam, Rainer Schultze-Kraft, Ha Dinh Tuan, Nguyen Phung Ha

IGC Proceedings (1993-2023)

A mission to collect germplasm of native legumes with forage potential was carried out In February-March 1992 In Vietnam, The collection route essentially followed a North-to-South transect and covered a wide range of ecological conditions between Hanoi and Ho Chi Minh City. Altogether 195 samples of at least 25 genera weie collected. 639' of the samples corresponded lo species within the high-priority genus Desmodlum, Its related genera Dendrobium, Hegnera, Pliyllodlum and Tadehagl, and the genus Puerarla, The native legume Dora is severely endangered by genetic erosion and areas for urgent future collection missions were ldenlifled.


Growth Characteristics Of Hordeum Bulbosum L. And Its Use As Fodder, H Hirota, A Goto Aug 2024

Growth Characteristics Of Hordeum Bulbosum L. And Its Use As Fodder, H Hirota, A Goto

IGC Proceedings (1993-2023)

Pot experiments were conducted to evaluate herbage production and feeding value of Hordeum bulbosum L. during 1988-1990. After spring sowing, tiller and leaf number increased remarkably until the autumn of the seeding year. Three cuttings with 2-month intervals from June gave high production. With autumn sowing, 3-4 cuttings in a growing season assured good regrowth and high production during 2 years after sowing. This grass is of high herbage quality except in heading stage.


Effect Of Management And Cultivar On Nodal Root Development Of White Clover, J R. Caradus, D F. Chapman, R A. Skipp Aug 2024

Effect Of Management And Cultivar On Nodal Root Development Of White Clover, J R. Caradus, D F. Chapman, R A. Skipp

IGC Proceedings (1993-2023)

Nodal root development of white clover (Trifolium repens L.) swards was monitored by harvesting marked nodes from late autumn to spring and by taking tiller plugs over 15 months. At a hill country site Grasslands Huia and a large-leaved French eultivar, Crau, had greater nodal root development, in terms of root length, than a small­leaved hill country ecotype. Compadson of the effects of rotational sheep and cattle grazing at both lowland and hill country sites showed greater nodal root development root length and lateral root production under cattle grazing. Percentage of nodes with roots was greater under rotational than set-stocked …


Morphogenetic And Structural Determinants Of Plant Regrowth After Defoliation, D F. Chapman, G Lemaire Aug 2024

Morphogenetic And Structural Determinants Of Plant Regrowth After Defoliation, D F. Chapman, G Lemaire

IGC Proceedings (1993-2023)

Responses of forage plants to defoliation can be delineated at two levels: physiological responses and morphological responses. Physiological responses are generally defined as occurring over short time-scales, whereas morphological responses are generally considered as being long-t<;rm. The extent to which physiological and morphological responses influence pasture characteristics and production depends on the defoliation regime, and the balance obtained between the supply and demand of growth resources by plants. Where defoliation is relatively infrequent and lax, plants may maintain balanced growth of root and shoot purely through short­term physiological responses. However, as defoliation severity increases, morphological adjustments are needed to ensure homeostatic, whole-plant growth. The adaptability of forage species to various points on the continuum of defoliation pressure from lenient to severe depends on their inherent morphological and physiological characteristics. We concentrate on morphogenetic and structural determinants of plant regrowth following defoliation, drawing out the important linkages with the physiological responses. We examine the relationships between plant morphogenesis and sward structure, placing particular emphasis on phcnotypic plasticity as a process whereby plant and population structure can alter to maintain homeostatic growth in response to variation in defoliation management. The imporlnnce of meristem positioning within the sward and of meristem activity, interacting with defoliation management, as determinants of plant production and persistence is discussed. Relationships between plant morphogenesis, herbage growth dynamics and barvestable herbage production are examined and we identify the collection of fundamental physiological and morphological information for a wider array of forage species as an important research goal for improving the productivity and sustainability of the world's grasslands.