Defoliation in Relation to Vegetative Growth

Hyder, D. N.

doi:10.1016/b978-0-12-774750-7.50028-2

Cited by 66 publications

(42 citation statements)

References 21 publications

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“…Stems are typically lower in protein and digestibility than their accompanying leaves (Hacker and Minson 1981, Buxton and Marten 1989, Bidlack et al 1999 In 1992, spring soil moisture was not adequate to carry tillers to maturity. In response, adolescent tillers most likely became quiescent and then responded to June precipitation with renewed growth and a belated effort to reach maturity (Hyder 1972). Because nearly all tillers reached maturity by mid-summer in 1993, there were few if any live stems that could capitalize on July precipitation.…”

Section: Discussionmentioning

confidence: 99%

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Nutritional dynamics of 7 northern Great Basin grasses

Ganskopp¹,

Bohnert²

2001

REM

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Land, livestock, and wildlife managers need to understand the nutritional dynamics of forages to sustain adequate growth and reproduction of their animals and/or assure equitable payment for forages. Despite a long history of livestock grazing in the northern Great Basin, seasonal and annual nutritional dynamics of many of the region's prominent grasses have not been described. We addressed this issue via monthly sampling of 7 cool-season grasses at 6 sites during 1992, a drier than average year having 86% of mean precipitation, and 1993, when above average precipitation (167% of average) occurred. With high yields predicted in 1993 (1,257 kg ha -1 ), the period of adequate forage quality [crude protein (CP) ≥ 7.5%] was 83 days. In addition grasses did not respond to 97 mm of July-August rain with renewed growth. During 1992, a growing season beginning with less than average moisture, grasses responded to midsummer (49 mm) and fall (69 mm) rains by maintaining greater than 7.5% CP for 185 days. A diversity of grasses expanded the period of adequate forage quality especially during the lower than average moisture year. Giant wildrye (Elymus cinereus Scribn. & Merr.), a deeply rooted grass, supported high quality forage until mid August, but did not respond to late-season moisture. In contrast, shallow rooted grasses like bottlebrush squirreltail (Sitanion hystrix (Nutt.) Smith), Sandberg's bluegrass (Poa sandbergii Vasey), and the winter-annual cheatgrass (Bromus tectorum L.) responded to summer or fall moisture with herbage ranging from 10 to 16% CP, thereby supplying high quality late-season forage. With most precipitation occurring in the northern Great Basin during colder months, livestock or habitat managers can, with a fair degree of certainty, predict yields from their pastures before turnout. With abundant moisture, managers will see the rapid deterioration of forage quality that occurs when grasses advance through their reproductive stages of phenology and generate a wealth of reproductive stems. The quandary arrives, however, when moisture accumulations are less than optimum. Fewer reproductive tillers develop, and our results show that timely precipitation may elevate desirable nutrient characteristics and expand the duration of adequate livestock/wildlife nutrition in the region. More long-term research is needed to decipher the mechanisms governing growth and development of rangeland grasses and to assess risks of various stocking alternatives when managers face uncertain yield and forage quality issues. ResumenLos manejadores de tierras, ganado y fauna silvestre necesitan entender las dinámicas nutricionales de los forrajes para mantener un crecimiento y una reproducción adecuados de sus animales y/o asegurar el pago equitativo de sus forrajes. A pesar del largo historial de apacentamiento de ganado en la Gran Cuenca del norte, las dinámicas nutricionales estacionales y anuales de muchos de los zacates prominentes de la región no se han sido descritas. Nosotros abordamos este problema a tra...

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Section: Discussionmentioning

confidence: 99%

“…2). Hyder (1972) suggested bottlebrush squirreltail frequently supports culmless vegetative tillers that may be able to respond and differentiate with favorable conditions through the summer. In many years we have observed bottlebrush squirreltail flowering throughout the growing season.…”

Section: Discussionmentioning

confidence: 99%

Nutritional dynamics of 7 northern Great Basin grasses

Ganskopp¹,

Bohnert²

2001

REM

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“…À medida que houve o avanço da estação (ciclos), ocorreu redução nos ângulos foliares médios (médias das quatro datas durante a rebrota) em resposta ao pastejo (Figura 5). No tratamento de menor resíduo de massa seca verde pós-pastejo (1.000 kg ha -1 ), as plantas apresentaram essa modificação morfológica mais proeminente para, provavelmente, compensar a reduzida área fotossinteticamente ativa com maior interceptação de luz por unidade de área de folha (Kidd, 1966;Hyder, 1972;Matches, 1992). Kidd (1966), trabalhando com duas taxas de lotação (alta e baixa) em azevém-perene, constatou que plantas severamente pastejadas (alta lotação), rapidamente assumiram hábito de crescimento prostrado, demonstrado por perfilhamento horizontal, originário da porção basal das plantas.…”

Section: âNgulos Foliares Médiosunclassified

Respostas morfológicas do capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia-1) irrigado à intensidade de desfolha sob lotação rotacionada

Mello

Pedreira

2004

R. Bras. Zootec.

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RESUMO -Objetivando quantificar respostas morfológicas de dosséis de capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia-1) sob três intensidades de pastejo, lotação rotacionada e irrigação, foi conduzido um experimento em delineamento experimental de blocos completos casualizados com quatro repetições. Os tratamentos foram três intensidades de pastejo, representados pelas quantidades de massa seca verde residual pós-pastejo (T1=1000; T2=2500 e T3=4000 kg MSV/ha). Durante oito ciclos de pastejo (rebrotas de 33 dias após três dias de pastejo em cada ciclo), foram realizadas avaliações de altura média do dossel, índice de área foliar (IAF), interceptação luminosa (IL) e ângulos foliares médios, em quatro dias dentro do período de rebrota (1, 11, 22 e 33 dias após a saída dos animais). A análise de correlações parciais indicou correlações entre altura e IL, bem como entre IAF e IL. Com o progresso da estação de pastejo, da primavera-verão para outono-inverno, houve reduções nos valores de IAF médio. Valores médios de IAF crítico (95% IL) de 3,6 (T1), 4,0 (T2) e 4,5 (T3), foram alcançados por volta do 22 o dia das rebrotas. A maior intensidade de pastejo (menor resíduo) alterou a estrutura da pastagem no que diz respeito à arquitetura do dossel, evidenciada pela redução nos ângulos foliares médios (folhas mais horizontais) ao longo das estações, com plantas passando a interceptar mais luz por unidade de área foliar. Os IAFs críticos medidos sugerem a necessidade de períodos de descanso menores que 33 dias em pastos de capim-Tanzânia, quando submetido a pastejo intensivo sob lotação rotacionada e irrigação.Palavras-chave: ângulos foliares, altura, índice de área foliar, interceptação luminosa Morphological Responses of Irrigated Tanzaniagrass (Panicum Maximum Jacq. cv. Tanzania-1) to Grazing Intensity under Rotational StockingABSTRACT -The objective of this research was to quantify morphological responses of Tanzania grass (Panicum maximum Jacq. cv. Tanzania-1) under three grazing intensities in an irrigated, rotationally stocked setting. Treatments consisted of three grazing intensities represented by three post-graze forage masses (T1=1,000; T2=2,500, and T3=4,000 kg green dry mass/ha), in a randomized complete block design with four replications. During the grazing season (eight 36-d cycles; three days of grazing followed by 33 days rest), the following measurements were taken: mean sward height, leaf area index (LAI), light interception (LI), mean leaf angles, all measured on four occasions (1, 11, 22, and 33 days after grazing) of each rest period. Partial correlation analysis indicated the existence of correlation between height and LI, as well as between LAI and LI. As the grazing season progressed from spring-summer to autumnwinter, mean LAI declined. Mean critical LAI (95% LI) was 3.6 (T1), 4.0 (T2), and 4.5 (T3) and was always reached around the 22 nd day after grazing. Over the season, hard grazing (lower residual mass) altered the sward structure causing shifts in plant architecture, as shown by reduced le...

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“…As long as the tiller remains vegetative, the apical meristem is indeterminate and, theoretically, an infinite number of phyllochrons can occur. When spikelet prirnordia appear, there is no potential for further initiation of leaves and the shoot apex becomes determinate (Hyder, 1972;Langer , 1979). Elongation is the period during which internodes elongate.…”

Section: Developmental Morphologymentioning

confidence: 99%