The physiology of tiller death in grasses. 2. Causes of tiller death in a grass sward

Ong, C. K.; Marshall, Christopher D.; Saoar, G. R.

doi:10.1111/j.1365-2494.1978.tb00821.x

Cited by 67 publications

(58 citation statements)

References 14 publications

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“…A morte de perfilhos vegetativos resulta de muitos processos, incluindo sombreamento, pastejo severo, arranquio, deposição de fezes e urina, pisoteio, florescimento, competição por nutrientes, doenças e predação por insetos (Ong et al, 1978;Matthew et al, 1996). A principal causa da morte de perfilhos vegetativos é o sombreamento de pequenos perfilhos devido ao aumento da massa de forragem no relvado (Ong et al, 1978;L'Huillier, 1987).…”

Section: Introductionunclassified

“…A principal causa da morte de perfilhos vegetativos é o sombreamento de pequenos perfilhos devido ao aumento da massa de forragem no relvado (Ong et al, 1978;L'Huillier, 1987). Já a principal causa da mortalidade de perfilhos reprodutivos é atribuída ao pastejo, pois quando uma pequena porção do caule é removida pelos animais durante essa fase de desenvolvimento da planta, o perfilho todo morre (Chapman et al, 1984;L'Huillier, 1987).…”

Section: Introductionunclassified

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Demografia do perfilhamento e taxas de acúmulo de matéria seca em capim 'Tifton 85' sob pastejo

Carvalho

Silva

Sbrissia

et al. 2000

Sci. agric. (Piracicaba, Braz.)

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RESUMO: Neste ensaio foram avaliados os parâmetros de densidade populacional, taxas de emissão e de mortalidade, proporção de perfilhos florescidos e acúmulo de matéria seca de forragem para a espécie Cynodon spp. cultivar Tifton 85. Os tratamentos corresponderam a quatro situações de altura do pasto (5, 10, 15 e 20 cm) mantidas constantes por ovinos sob regime de lotação contínua e taxa de lotação variável. O delineamento experimental foi o de blocos completos casualizados com quatro repetições. Foram utilizadas áreas (≅ 0,0176 m 2 ) delimitadas por anéis plásticos (PVC), onde todos os perfilhos existentes foram marcados com pequenas argolas plásticas coloridas e contados a cada avaliação. As taxas de acúmulo de matéria seca foram avaliadas utilizando-se a técnica da gaiola de exclusão, com mensuração da massa de forragem a cada 21 dias. Houve efeito (P<0,10) de data e/ou período de amostragem sobre todas as variáveis estudadas. As maiores densidades populacionais foram verificadas para os pastos mantidos baixos (5 cm), bem como as maiores taxas de aparecimento e mortalidade. As taxas de mortalidade foram determinantes básicos das densidades populacionais de perfilhos. Ocorreu grande renovação da população de perfilhos durante a estação do verão. Não houve efeito (P>0,10) de tratamento sobre as taxas de acúmulo de forragem. Palavras-chave: população de perfilhos, mortalidade, florescimento, acúmulo de forragem TILLER DEMOGRAPHY AND DRY MATTER ACCUMULATION RATES IN 'TIFTON 85' SWARDS UNDER GRAZINGABSTRACT: The aim of this study was to verify patterns of tiller population density, tiller appearance and mortality rates, proportion of flowering tillers and herbage dry matter accumulation for Cynodon spp. (cv. Tifton 85). Treatments corresponded to four "steady state" conditions characterised by sward surface heights of 5, 10, 15, and 20 cm, maintained by sheep grazing under continuous stocking and variable stocking rate. Treatments were allocated to experimental units (400 m 2 each) according to a completetely randomised block design with four replication. Tillering evaluations consisted of tagging and counting all tillers present and new tillers emerging within two 15 cm diameter plastic rings (PVC) per experimental unit. Herbage accumulation was measured using exclosure cages rotated every three weeks. There was a time effect (P<0,10) for all response variables studied. Short swards (5 cm) presented the highest values for tiller population densities as well as the highest rates of tiller appearance and mortality. Tiller mortality rates were very influential on tiller density population. A great turnover in tiller population occurred during the summer period, suggesting that a high tiller population density should be maintained during autumn and winter. There was no treatment effect on herbage accumulation rates (P>0,10).

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Section: Introductionunclassified

Demografia do perfilhamento e taxas de acúmulo de matéria seca em capim 'Tifton 85' sob pastejo

Carvalho

Silva

Sbrissia

et al. 2000

Sci. agric. (Piracicaba, Braz.)

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“…Accumulation of a large herbage mass is a major cause of tiller death (Ong et al 1978;Cartonet al 1989)so a short intervalbetween grazings isfavouredfor maintenance of tillerdensity (L ,Huillier 1987a). Stress factors like severe defoliation (stubble height < 2.5 em) and physical damage (dung, urine scorch), can also lead to tiller and plant death and sward deterioration (Wade & Baker 1979;Tallowin 1981;Thom et al 1986b).…”

Section: Introductionmentioning

confidence: 99%

Effect of early spring grazing frequency on the reproductive growth and development of a perennial ryegrass tiller population

Thom¹

1991

New Zealand Journal of Agricultural Research

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A population (1188) of vegetative perennial ryegrass tillers was identified at random in nine paddocks of an existing farmlet experiment. Groups of three paddocks (396 of identified tillers) were grazed every 8, 16, and 32 days from mid August until early November 1984, after which all paddocks were grazed every 32 days until the end of the experiment in May 1985. The physiologicalstatus (vegetative or reproductive) oflive marked tillers and their orientation in the sward were determined at 7-12-day intervals during the experiment. Paddock botanical composition and tiller densitywere recorded in October, December, February, and May. Fifty percent of marked tillers became reproductive during the experiment. Reproductive development was concentrated in late October/early November. Different spring grazing frequencies did not affect reproductive development but frequent grazing resulted in tillers that were more prostrate than when grazing was less frequent. Reproductive tillers had a higher overall probability (P = 0.24 per week) of dying than did vegetative tillers (P = 0.09 per week), regardless of grazing treatment. Defoliation during summer/autumnsignificantlyincreasedthe probability of vegetative tiller death. A fast spring rotation increased ryegrass and Poa tiller densities in October after which the effects disappeared.

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“…Dung deposition and constant grazing can also increase N and P contents of soil and grasses in feeding areas (McNaugthon 1984). Grasses further benefit from grass tuft removal because the risk of fire and grass mortality through self-shading are reduced (Ong et al 1978).…”

Section: Introductionmentioning

confidence: 99%

Tree size and herbivory determine below-canopy grass quality and species composition in savannahs

2009

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Large single-standing trees are rapidly declining in savannahs, ecosystems supporting a high diversity of large herbivorous mammals. Savannah trees are important as they support both a unique flora and fauna. The herbaceous layer in particular responds to the structural and functional properties of a tree. As shrubland expands stem thickening occurs and large trees are replaced by smaller trees. Here we examine whether small trees are as effective in providing advantages for grasses growing beneath their crowns as large trees are. The role of herbivory in this positive tree-grass interaction is also investigated. We assessed soil and grass nutrient content, structural properties, and herbaceous species composition beneath trees of three size classes and under two grazing regimes in a South African savannah. We found that grass leaf content (N and P) beneath the crowns of particularly large (ca. 3.5 m) and very large trees (ca. 9 m) was as much as 40% greater than the same grass species not growing under a tree canopy, whereas nutrient contents of grasses did not differ beneath small trees (\2.3 m). Moderate herbivory enhanced these effects slightly. Grass species composition differed beneath and beyond the tree canopy but not between tree size classes. As large trees significantly improve the grass nutrient quality for grazers in contrast to smaller trees, the decline of the former should be halted. The presence of trees further increases grass species diversity and patchiness by favouring shade-tolerant species. Both grazing wildlife and livestock will benefit from the presence of large trees because of their structural and functional importance for savannahs.

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The physiology of tiller death in grasses. 2. Causes of tiller death in a grass sward

Cited by 67 publications

References 14 publications

Demografia do perfilhamento e taxas de acúmulo de matéria seca em capim 'Tifton 85' sob pastejo

Demografia do perfilhamento e taxas de acúmulo de matéria seca em capim 'Tifton 85' sob pastejo

Effect of early spring grazing frequency on the reproductive growth and development of a perennial ryegrass tiller population

Tree size and herbivory determine below-canopy grass quality and species composition in savannahs

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