Tussock Regrowth after Grazing: Intercalary Meristem and Axillary Bud Activity of Tillers of Agropyron desertorum

Olson, Bret E.; Richards, James H.

doi:10.2307/3565321

Cited by 62 publications

(37 citation statements)

References 29 publications

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“…Apesar de o pastejo estimular o perfilhamento (Olson & Richards, 1988;Reece et al, 1999;Dong et al, 2004), as condições ambientais no período da seca não são favorá-veis ao desenvolvimento de novos perfilhos (Laude et al, 1968), visto que a deficiência hídrica afeta a taxa de aparecimento de perfilhos (Morales et al, 1997).…”

Section: Dead Materials Stem Green Bladeunclassified

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

Cunha

Santos

Lira³

et al. 2007

R. Bras. Zootec.

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O experimento foi realizado com o objetivo de estudar características estruturais e morfológicas de cinco genótipos de Pennisetum sp. (CE 08 A.D., Venezuela, HV-241, Elefante B e Hexaplóide) sob pastejo no período de seca na Zona da Mata de Pernambuco. Os genótipos foram manejados sob lotação rotacionada (44 dias de descanso e quatro dias de pastejo) ao longo de dois ciclos de pastejo. Os dados foram analisados em delineamento experimental de blocos ao acaso com parcelas subdivididas (os genótipos representaram as parcelas e os ciclos de pastejo, as subparcelas) e quatro repetições. Houve variação nas características estruturais e morfológicas de genótipos de Pennisetum sp. Os genótipos CE 08 A.D. e Elefante B apresentaram maior densidade de lâmina foliar verde, menor porcentagem de material morto e maior densidade de perfilhos basais remanescentes e aéreos novos, com médias de 5,0±0,4 kg de MS/ha/cm, 33,0±0,2%, 22,0±0,2 e 146,0±0,4 perfilhos/m², respectivamente. O HV-241 apresentou alta participação de material morto em sua biomassa aérea (55,6±0,3%), o que pode ser atribuído à alta mortalidade de perfilhos (19,0±0,3 e 114,0±0,4 perfilhos basais e aéreos mortos/m², respectivamente). Os genótipos CE 08 A.D. e Elefante B destacaram-se como promissores para utilização sob pastejo no período de seca. O genótipo HV-241, híbrido de capim-elefante com o milheto, foi mais afetado pelos efeitos do estresse hídrico no período seco do ano.

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Section: Dead Materials Stem Green Bladeunclassified

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

Cunha

Santos

Lira³

et al. 2007

R. Bras. Zootec.

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“…Axillary buds are rudimentary apical meristems dierentiated from the apical meristems of parental tillers that can potentially grow out to produce juvenile tillers (Sharman 1945;Langer 1963). It is generally recognized that tiller initiation and growth are suppressed by suboptimal environmental conditions (Langer 1963), including drought (Busso et al 1989;Van Loo 1992) and severe defoliation (Olson and Richards 1988;Murphy and Briske 1992). In addition, the transient nature (<1 year) of seed banks of temperate perennial grasses is well documented (Thompson and Grime 1979;Pyke 1990).…”

Section: Introductionmentioning

confidence: 98%

Axillary bud banks of two semiarid perennial grasses: occurrence, longevity, and contribution to population persistence

Hendrickson

Briske

1997

Oecologia

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The occurrence, longevity, and contribution of axillary bud banks to population maintenance were investigated in a late-seral perennial grass, Bouteloua curtipendula, and a mid-seral perennial grass, Hilaria belangeri, in a semiarid oak-juniper savanna. Axillary buds of both species were evaluated over a 2-year period in communities with contrasting histories of grazing by domestic herbivores. A double staining procedure utilizing triphenyl tetrazolium chloride and Evan's blue indicated that both viable and dormant axillary buds remained attached to the base of reproductive parental tillers for 18-24 months which exceeded parental tiller longevity by approximately 12 months. Bud longevity of the late-seral species, B. curtipendula, exceeded bud longevity of the mid-seral species, H. belangeri, by approximately 6 months. Younger buds located on the distal portion of the tiller base were 3.2 and 1.4 times more likely to grow out than older proximal buds of B. curtipendula and H. belangeri, respectively. The percentage of older proximal buds, which included comparable portions of viable and dormant buds, that grew out to produce tillers following mortality of parental tillers was 6.0% for B. curtipendula and 8.4% for H. belangeri. In spite of the occurrence of relative large axillary bud banks for both species, the magnitude of proximal bud growth did not appear sufficient to maintain viable tiller populations. We found no evidence to support the hypothesis of compensatory bud growth on an individual tiller basis for either species. Grazing history of the communities from which the buds were collected did not substantially affect the number, status, longevity, or outgrowth of axillary buds on an individual tiller basis for either species. However, long-term grazing by domestic herbivores influenced axillary bud availability by modifying population structure of these two species. Bud number per square meter for B. curtipendula was 25% lower in the long-term grazed compared to the long-term ungrazed community based on a reduction in both tiller number per plant and plant number per square meter. In contrast, bud number per square meter for H. belangeri was 190% greater in the long-term grazed than in the long-term ungrazed community based on a large increase in plant density per square meter. Minimal contributions of axillary bud banks to annual maintenance of tiller populations in this mid- and late-seral species underscores the ecological importance of consistent tiller recruitment from recently developed axillary buds. Consistent tiller recruitment in grasslands and savannas characterized by intensive grazing and periodic drought implies that (1) bud differentiation and maturation must be remarkably tolerant of adverse environmental conditions and/or (2) tiller recruitment may resume from buds that mature following the cessation of severe drought and/or grazing, rather than from mature buds that survive these disturbances. These scenarios warrant additional research emphasis given the critical importance of this de...

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“…Delayed production of new tillers until the following spring contrasts with desert wheatgrass in which new tillers developed during the growing season within one to two months (Caldwell et al 1981) or two to three weeks of defoliation (Olson and Richards 1988b). In all years, tillers of crested wheatgrass emerged the April following defoliation.…”

Section: Discussionmentioning

confidence: 99%

Regrowth of crested wheatgrass (Agropyron cristatum [L.] Gaertn.) following defoliation

Romo¹,

Harrison²

1999

Can. J. Plant Sci.

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] Gaertn.) on the amount of time required to reach peak regrowth, the lag period for regrowth to begin, regrowth biomass, tiller survival and replacement, and carryover effects of defoliation the following year were investigated. Regrowth of crested wheatgrass was determined during the summers of 1990, 1991 and 1992 in central Saskatchewan following a single defoliation to a 5-cm stubble height at eight stages of growth. Crested wheatgrass regrew 54-130 g m -2 of biomass when defoliated tillers had ≤3.6 leaves. Regrowth began accumulating within 3-53 growing degree-days (GDD) and peaked in 705-875 GDD. Rates of leaf development after defoliation (218-252 GDD phyllochron -1 ) equaled or were faster than control (218-330 GDD phyllochron -1 ). Regrowth biomass accounted for 35-76% of total annual production. Total annual production was greatest when plants were defoliated during vegetative growth or at peak growth. In 1991 and 1992, etiolated growth in the spring following defoliation was reduced by defoliation in the previous year. Tiller replacement was not affected by defoliation and averaged 1.2 tillers tiller -1 (SE = 0.1) in 1991 and 1.5 tillers tiller -1 (SE = 0.1) in 1992. Two periods of grazing can be expected from crested wheatgrass if it is grazed when tillers have ≤3.6 leaves; however, the impacts of a second grazing must be determined. If crested wheatgrass is grazed late in the growing season, only one period of grazing can be expected, and production will likely be less the following growing season, necessitating a rest period for plants to regain their production potential. ] Gaertn) sur la durée de repos avant la reprise de la croissance, sur le temps nécessaire pour atteindre la repousse maximale, sur la biomasse de la repousse, sur la survie et sur le renouvellement des talles, ainsi que les arrière-effets sur la croissance l'année suivante. La repousse de la graminée était mesurée au cours des étés 1990, 1991 et 1992 dans le centre de la Saskatchewan à la suite d'une seule fauche à la hauteur de 5 cm, effectuée à 8 stades de croissance. La repousse atteignait 54 à 130 g de biomasse au mètre carré (m 2 ) quand les talles étaient coupées lorsqu'elles ne portaient pas plus de 3,6 feuilles chacune. Elle commençait à s'accroître au bout de 3 à 53 degré-jours de croissance (DJC), pour atteindre son maximum aux alentours de 705-875 DJC. Le taux de croissance foliaire après défoliation, soit 218 à 252 DJC par feuille, était égal ou plus rapide que celui observé dans les parcelles témoins (218-330 DJC). La biomasse de la repousse représentait de 35 à 76 % de la production annuelle totale. Cette dernière était à son maximum lorsque la fauche avait été exécutée durant la phase végétative ou au niveau de croissance maximum. En 1991 et en 1992, la croissance étiolée au printemps suivant l'année de défoliation était diminuée. Le renouvellement des talles n'était pas touché par le régime de fauche et se maintenait aux alentours de 1,2 talles par talle morte (ET = 0,1) en 1991 et à 1,5 en 1992. On peut donc obt...

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Tussock Regrowth after Grazing: Intercalary Meristem and Axillary Bud Activity of Tillers of Agropyron desertorum

Cited by 62 publications

References 29 publications

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

Características estruturais e morfológicas de genótipos de Pennisetum sp. sob pastejo no período de seca

Axillary bud banks of two semiarid perennial grasses: occurrence, longevity, and contribution to population persistence

Regrowth of crested wheatgrass (Agropyron cristatum [L.] Gaertn.) following defoliation

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