Sward management, lamina turnover and tiller population density in continuously stocked <i>Lolium perenne</i>‐dominated swards

Grant, Sheila; Barthram, G. T.; Torvell, L.; King, John L.; Smith, H. K.

doi:10.1111/j.1365-2494.1983.tb01657.x

Cited by 125 publications

(114 citation statements)

References 11 publications

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“…Given that tetraploids generally have a more open growth habit with a reduced number of tillers per plant, it was notable that this category did achieve positive density gain values, though none were significantly increased. It has been suggested that increased herbage production of grasses may be attributed to increases in tiller density or tiller weight or a combination of both (Nelson and Zarrough 1981;Bircham and Hodgson 1983;Grant et al 1983;Volenec and Nelson 1983). However, the indication from the current study is that breeders have not sacrificed nor improved sward density significantly to achieve yield gains.…”

Section: Discussioncontrasting

confidence: 49%

Genetic gain in perennial ryegrass (Lolium perenne) varieties 1973 to 2013

et al. 2016

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Perennial ryegrass (Lolium perenne) forms the basis of grassland production in temperate pastures and is globally one of the most important forage grasses. Consequently, there has been large plant breeding industry investment over the past 40 years in producing new varieties and independent testing systems designed to identify and list those with the most improved performances. This study was conducted at the Plant Testing Station, Crossnacreevy, Northern Ireland and compared the DM yield and sward density of new varieties submitted from 1973 to 2013 and grass digestibility from 1980 to 2013, under conservation and simulated grazing managements. A variety 9 years matrix was compiled for each parameter and comparable means between varieties never in side by side performance trials were produced. Dry matter yields showed an overall significant (p \ 0.001) average annual increase of 0.52 % under conservation and 0.35 % under simulated grazing, with similar gain levels within maturity groups or ploidies. These rates were not constant over time, and periods of no gain occurred in various variety groupings. Sward density of the examined varieties did not change significantly. Herbage digestibility showed no improvement over the timeframe but had the largest differences between concurrent varieties, indicating that improvements were possible in the future. The study indicated that plant breeding gains were primarily DM yield focused with sward density remaining stagnant over the 40 years, while the lack of grass digestibility improvement appeared to only require more time to overcome. Evidence of benefits and risks of variety testing influences on plant breeding objectives was discussed.

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Section: Discussioncontrasting

confidence: 49%

Genetic gain in perennial ryegrass (Lolium perenne) varieties 1973 to 2013

et al. 2016

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“…Grant et al (1983) stated that seasonal variation in solar radiation and sward herbage mass are the main determinants of tiller population density, indicating that tiller population is frequently being adjusted. The persistency and productivity of grass swards are directly dependent of the combined effect of tiller appearance and death (Matthew et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Sward structure of marandu palisadegrass subjected to continuous stocking and nitrogen-induced rhythms of growth

Pereira

Paiva

Silva

et al. 2010

Sci. agric. (Piracicaba, Braz.)

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Acceleration of the growth rhythm of plants using nitrogen fertiliser alters the rates of physiological processes like growth and senescence and may cause significant changes in sward structure, interfering with plant and animal responses. The objective of this experiment was to evaluate sward structure of marandu palisadegrass (Brachiaria brizantha) maintained at 30 cm under continuous stocking and subjected to contrasting rhythms of growth from January 2007 to April 2008. These were generated using or not nitrogen fertiliser, and comprised four experimental treatments as follows: control (non-fertilised), 150, 300 and 450 kg ha -1 of N. Acceleration of the growth rhythm of plants was associated with increases in leaf and stem bulk density, and resulted in larger LAI and total bulk density on swards subjected to faster (fertilised with 300 and 450 kg ha -1 of N) than those subjected to slower rhythms of growth (non-fertilised or fertilised with 150 kg ha -1 of N). Variations in dead material bulk density were associated with seasonal variations in climatic conditions, and were not influenced by growth rhythms. During autumn/winter and early spring (dry period of the year) swards subjected to faster, relative to those subjected to slower rhythms of growth, had larger proportion of leaves on the top horizons. On the other hand, sward structure did not vary among rhythms of growth at times of the year when there was no limitation in the availability of climatic growth factors (late spring and summer), indicating that when control of the grazing process is efficient, changes in sward structure are basically a function of seasonal variations in climatic growth conditions and phenological state of plants. Key words: herbage bulk density, morphological composition, grazing management, nitrogen Estrutura do dossel forrageiro de pastos de capim-marandu submetidos à lotação contínua e ritmos de crescimento induzidos por adubação nitrogenada RESUMO: A aceleração do ritmo de crescimento das plantas por meio da adubação nitrogenada altera a velocidade dos processos fisiológicos, atuando sobre o crescimento e a senescência, podendo refletir-se em alterações importantes sobre a estrutura do dossel. Avaliou-se a estrutura do dossel forrageiro de pastos de capim-marandu (Brachiaria brizantha) mantidos a 30 cm de altura por meio de lotação contínua e submetidos a ritmos de crescimento contrastantes de janeiro de 2007 a abril de 2008. Os distintos ritmos de crescimento foram criados por meio da utilização de adubação nitrogenada, segundo os tratamentos: sem adubação (controle), 150, 300 e 450 kg ha -1 de N. A aceleração do ritmo de crescimento dos pastos resultou em aumentos de densidade volumétrica de folhas e de colmos, refletindo em maior IAF e densidade volumétrica total em pastos submetidos aos ritmos de crescimento mais acelerados (adubados com 300 e 450 kg ha -1 de N) relativamente àqueles submetidos a ritmos de crescimento mais lentos (pastos não adubados e/ou adubados com 150 kg ha -1 de N). Variações em densid...

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“…The use of grazing exclusion cages is probably responsible for the non-detection of differences in FARs at different heights, as they can cause overestimation of FAR in lower canopies and underestimation of those kept higher (Bortolo et al 2001;Molan, 2004). However, Grant et al (1983) and Bircham & Hodgson (1983) reported that the tiller size/density compensation in plant communities subjected to defoliation can make large variations between defoliation regimes result in small differences in the total amount of leaves produced per unit area. This compensation mechanism has been confirmed in several studies with tropical grasses kept under continuous stocking at different canopy heights (Carvalho et al 2000;Sbrissa et al 2001Sbrissa et al , 2003Sbrissa & Da Silva, 2008).…”

Section: Variablesmentioning

confidence: 99%

Tillering and forage accumulation in Marandu grass under different grazing intensities

Calvano

Euclides²,

Montagner³

et al. 2011

Rev. Ceres

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Studies of plant responses to defoliation are important to develop pasture management strategies. The objective of this study was to evaluate the population density of basal, aerial and reproductive tillers, tiller appearance and mortality rates, forage accumulation and sward structure in Marandu grass pastures under different grazing intensities. The experimental period was from January to June 2006, divided in three seasons: summer, autumn and winter. The pastures were continuously grazed using variable stocking rates. The grazing intensities corresponded to 15, 30 and 45 cm of sward height. The experiment was arranged in a complete randomized block design with three treatments and two replicates. The sward heights were measured twice a week. The response variables were: forage accumulation, forage mass and its morphological components; and population densities of basal (TPDb), aerial (TPDa) and reproductive (TPDr) tillers. The highest TPDb (P > 0.05) was recorded for the shortest sward pasture, and the highest TPDr (P<0.05) for the tallest sward pasture. Swards showed a tiller size/density compensation mechanism and, consequently, the forage accumulation was similar (P > 0.05) among the grazing intensities. Pasture with a sward height of 35 cm had 94% of sun light interception. The highest variations in forage accumulation and sward structure were more influenced by seasonal differences than by grazing intensities. Pastures of Marandu grass showed large flexibility in grazing management, which allowed it to be maintained at sward heights between 15 and 35 cm.

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Sward management, lamina turnover and tiller population density in continuously stocked Lolium perenne‐dominated swards

Cited by 125 publications

References 11 publications

Genetic gain in perennial ryegrass (Lolium perenne) varieties 1973 to 2013

Genetic gain in perennial ryegrass (Lolium perenne) varieties 1973 to 2013

Sward structure of marandu palisadegrass subjected to continuous stocking and nitrogen-induced rhythms of growth

Tillering and forage accumulation in Marandu grass under different grazing intensities

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