Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Sugarcane yellow leaf virus, the causal agent of yellow leaf, is transmitted from plant to plant by aphids. Understanding and evaluating the epidemic risks due to spread of yellow leaf by aphids is an important feature for sugarcane production. Four distinct sugarcane trials were set up with disease-free plants to study the relationship between spread of yellow leaf, the vector dynamics and environmental conditions that may favour yellow leaf epidemics. The study was performed by surveys of vector populations and determination of plant infections. Sugarcane cultivar SP71-6163, highly susceptible to yellow leaf, was analyzed spatially at different dates in all four trials and compared to commercial cultivars in two of the four trials. These surveys allowed us to identify a correlation between the aphid dynamics in the field and yellow leaf progress. Additionally, a negative correlation was found between rainfall during the first weeks after transferring sugarcane plants to the field and aphid dispersal within the field. This later result revealed an impact of rainfall on aphid invasion and subsequent plant infection by SCYLV. If aphids are the key factor for disease spread, plant response varied also according to cultivar resistance with high variation depending on rain conditions.
ISSN: 0929-1873

hal-00684227
https://hal.archives-ouvertes.fr/hal-00684227

Résumé : Arbolito de 6 a 8 m, ramas jóvenes hirsutas. Hojas corto-pecioladas u obovado-oblongas de 15 a 30 cm, abruptamente acuminadas, redondeadas u obtusas en la base. Inflorescencia pequeña, cauliflora; flores largamente pecioladas; cáliz rosado, de 6-7 mm; pétalos amarillos. Fruto glabro, ovoide-oblongo, gradualmente atenuado en el ápice, 10-sulcado, los surcos irregularmente rugosos-tuberculados; semillas ovoideas.
Petit arbre de 6 à 8 m, branches jeunes hirsutes. Feuilles à court pétiole ou ovées-oblongues de 15 à 30 cm, se terminant brusquement en pointe, base arrondie, ou obtuse. Inflorescence petite, caulinaire; fleurs à long pétiole; calice rosé, de 6-7 mm; pétales jaunes. Fruit glabre, ovoïde-oblongue, dont l’extrémité s’affine graduellement, avec 10 sillons irrégulièrement rugueux-tuberculés, pulpe blanche sucrée; graines ovoïdes.
Small tree, 6- 8 (-12-14) m high.  Leaf, alternate, simple, entire, sinuate, petiole 1-2 cm, blades obovate-elliptic to oblong elliptic, 16-40 x 4.5-13 cm, base rounded to obtuse, apex acute; inflorescence axillary, 1-many flowered, clustered cymes, cauliflorous; petals white 4-4.5 mm long; fruit a glabrous, ellipsoid, leathery berry, 10-20 x 8-10 cm wide, ripening green, yellow, red or purple; seeds brown, ovoid or elliptic, 2-4x1.2-2 cm long with a sweet surrounding pulp.
Nativa de Mesoamérica y Sudamérica, cultivada ampliamente en los trópicos.
Originaire d’;Amérique centrale et d’;Amérique du sud, abondamment cultivée sous les tropiques.
Native to Middle and South America, widely cultivated in tropical r

http://www.tramil.net/fototeca/plant347

Résumé : Hierba o arbusto densamente ramificado. Hojas con pecíolo delgado, solitarias o en pares, ovadas u ovado-lanceoladas, ápice acuminado. Dos flores o más en cada nudo, rara vez una; cáliz truncado o con lóbulos diminutos; corola blanco-verdosa o blanco amarillenta. Fruto rojo, de 1.5 a 3 cm de diámetro, elipsoide-lanceolado o lanceolado, con ápice agudo. Semillas cremosas a amarillentas. Especie muy elastica con una gran cantidad de cultivares que poseen una gran diversidad de forma en sus frutos.
Herbe ou arbuste à ramifications denses. Feuilles avec pétiole fin, solitaires ou par paires, ovalées ou ovalées-lancéolées, acuminées. Deux fleurs ou plus sur chaque noeud, rarement une; calice tronqué ou à très petits lobes; corolle blanche-verdâtre ou blanche-jaunâtre. Fruit rouge, de 1,5 à 3 cm de diamètre, ellipsoïde-lancéolé ou lancéolé, acuminé. Graines de couleur crème à jaunâtre. Espèce très élastique par une grande quantité de cultivars possédant une grande variété de formes de fruits.
Annual shrub densely branching.  Leaf with thin petiole, either single or in pairs, ovate to ovate-lanceolate, with acuminate tip; flowers solitary or two or moreper node, 5-petals, whitish-green or whitish-yellow; fruit 1.5- 3.5 cm in diameter, ellipsoid-lanceolate or lanceolate with acute tip, crinkled, red, green, yellow or orange; seeds cream or yellowish.
Originaria de América tropical. Cultivada en zonas tropicales y templadas.
Originaire d';Amérique tropicale. Cultivée dans les zones tropicales et tempérées.
Tropical America.  Cultivated in regions with tropical and moderate climates.

http://www.tramil.net/fototeca/plant90

Résumé : Planta anual o perenne de 50 cm de alto, con ramas a veces reclinadas. Hojas alargadas, aovadas o punteadas de 3 a 7 cm de longitud. Flores en espigas de 1.5 a 3 cm de longitud que emergen desde las axilas de las hojas. Cápsulas pilosas de 2 mm.
Plante vivant un ou deux ans, de 50 cm de hauteur, avec des tiges à poils incurvés. Feuilles allongées, ovales ou pointues de 3 à 7 cm de longueur, à marges crénelées. Fleurs en épi mâles et femelles axillaires de 1,5 à 3 cm de longueur attachées à l';axe des feuilles. Fruit: capsule de 2 mm, velue.
Annual or perennial plant, up to 50 cm in height, with branches sometimes angling down.  Leaves elongated, ovate, or glandular-punctate, 3 to 7 cm in long.  Flowers, in spikes, 1.5 to 3 cm long, emerging from axillary leaf shoots; capsule 2 mm, pilose.
Sur de México hasta Perú y Bolivia. Presente también en las Pequeñas Antillas.  
Du Sud du Mexique jusqu';au Pérou et en Bolivie. Existe aussi dans les Petites Antilles.
From southern Mexico to Peru and Bolivia.  Also found in the L

http://www.tramil.net/fototeca/plant250

Résumé : Herbácea anual de 1-5 m de altura, raíces fibrosas. Hojas glabras o pilosas, de 1 m o más, acuminadas. Panícula estaminada de 20-35 cm de largo, racimos 3-40 sin una capa basal de abscisión, racimo terminal más grueso que los racimos laterales; inflorescencias pistiladas axilares, de unos 30 cm. Cariopsis desnudo con granos blancos, amarillos, rojizos; la mazorca rodeada por brácteas envolventes.
Herbacée annuelle de 1-5 m de haut, racines fibreuses. Feuilles glabres ou pileuses, de 1 m ou plus, acuminées. Panicule staminée de 20-35 cm de long. Inflorescence femelle axillaire longue de 30 cm environ formant un épis. Epi entouré de bractées enveloppantes, à nombreux grains au caryopes nus, de couleur jaune, rouge, violette etc.
Annual, monoecious, leafy succulent grass, 1-5 m high.  Leaves alternate at the nodes, 30-150 x 5-15 cm, glabrous or pubescent, linear-lanceolate, acuminate; male inflorescence, a large terminal panicle up to 40 cm long, female inflorescences in axillary sheath cobs, ca. 30 cm in length; fruit a grain or caryopsis white, yellow, reddish or purple.
Originaria de América, actualmente cosmopolita debido al cultivo.
Originaire du Mexique, aujourd’;hui cultivée partout dans le monde.
Native to America, now cosmopolitan (cultivated).

http://www.tramil.net/fototeca/plant362

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : The fixation of carbon in tropical forests mainly occurs through the production of wood and leaves, both being the principal components of net primary production. Currently field and satellite observations are independently used to describe the forest carbon cycle, but the link between satellite-derived forest phenology and field-derived forest productivity remains opaque. We used a unique combination of a MODIS enhanced vegetation index (EVI) dataset, a wood production model based on climate data and direct litterfall observations at an intra-annual timescale in order to question the synchronism of leaf and wood production in tropical forests. Even though leaf and wood biomass fluxes had the same range (respectively 2.4 +/- 1.4 and 2.2 +/- 0.4 Mg C ha(-1) yr(-1)), they occurred separately in time. EVI increased with leaf renewal at the beginning of the dry season, when solar irradiance was at its maximum. At this time, wood production stopped. At the onset of the rainy season, when new leaves were fully mature and water available again, wood production quickly increased to reach its maximum in less than a month, reflecting a change in carbon allocation from short-lived pools (leaves) to long-lived pools (wood). The time lag between peaks of EVI and wood production (109 days) revealed a substantial decoupling between the leaf renewal assumed to be driven by irradiance and the water-driven wood production. Our work is a first attempt to link EVI data, wood production and leaf phenology at a seasonal timescale in a tropical evergreen rainforest and pave the way to develop more sophisticated global carbon cycle models in tropical forests.
ISSN: 1726-4170

hal-01268497
https://hal.archives-ouvertes.fr/hal-01268497
DOI : 10.5194/bg-10-7307-2013
PRODINRA : 256018

Éditeur(s) : HAL CCSD Wiley
Résumé : Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree-based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions.
ISSN: 0006-3606

hal-01032411
https://hal.archives-ouvertes.fr/hal-01032411
DOI : 10.1111/j.1744-7429.2012.00902.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In French Guiana, Quassia amara L. (Simaroubaceae) leaf tea is a well-known widely used traditional antimalarial remedy. Impact of the vegetal sampling condition on in vivo and in vitro antimalarial activity was assessed. Traditional infusions were prepared with juvenile or mature leaves, both either fresh or dried. Results showed that growing stage and freshness of vegetal material exert a striking effect on antimalarial activity, both in vitro and in vivo. By far, leaf tea made from fresh juvenile (FJ) Quassia amara leaves was the most active. In vitro, active component (simalikalactone D) concentration correlates biological activities, although unexplained subtle variations were observed. In vivo, tea made with dried juvenile (DJ) leaves displays a peculiar behavior, meaning that some components may help simalikalactone D delivery or may be active in vivo only, therefore enhancing the expected curative effect of the traditional preparation.
ISSN: 0378-8741

hal-00384338
https://hal.archives-ouvertes.fr/hal-00384338
DOI : 10.1016/j.jep.2006.10.028

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Irradiance elicits a large plasticity in leaf traits, but little is known about the modulation of this plasticity by ontogeny. Interactive effects of relative irradiance and ontogeny were assessed on leaf traits for two tropical rainforest tree species: Dicorynia guianensis Amshoff and Tachigali melinonii (Harms) Barneby (Fabaceae, Caesalpinioideae). Eleven morphological and physiological leaf traits, relative to photosynthetic performance, were measured on saplings at three different architectural development stages (ASD 1, 2 and 3) and used to derive composite traits like photosynthetic N-use efficiency. Measurements were made along a natural irradiance gradient. The effect of ASD was very visible and differed between the two species. For Dicorynia guianensis, only leaf mass-per-area (LMA) significantly increased with ASDs whereas for Tachigali melinonii, almost all traits were affected by ASD: LMA, leaf N content and photosynthetic capacity increased from ASD 1 to ASD 3. Photosynthetic N-use-efficiency was not affected by ASD in any species. Leaf traits were severely modulated by irradiance, whereas the degree of plasticity was very similar among ASDs. Only few interactions were detected between irradiance and ASD, for leaf thickness, carbon content, and the ratio Chl/N in T. melinonii and for photosynthetic capacity in D. guianensis. We conclude that ontogenic development and irradiance-elicited plasticity modulated leaf traits, with almost no interaction, i.e., the degree of irradiance-elicited plasticity was stable across development stages and independent of ontogeny in these two species, at least in the early stages of development assessed here
ISSN: 1286-4560

halsde-00434378
https://hal.archives-ouvertes.fr/halsde-00434378
DOI : 10.1051/forest/2009062

Résumé : (Bibliography) Includes bibliographical references (leaf 158).
(Statement of Responsibility) Lennox E.A. Daisley, Eric D. Johnson, and Roger L. Francis.
"Caribbean Agricultural Research and Development Institute, Jamaica."
Jamaica
Jamaica
Saint Elizabeth
Jamaica
Saint Elizabeth

663453898
ocn663453898

Résumé : (Bibliography) Includes bibliographical references (leaf 26).
(Statement of Responsibility) Malcolm S. Davis., Patricia D. Davis.
(Funding) Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
Jamaica

74335150

Éditeur(s) : Universidad obrera Universidad obrera ( México )
Résumé : (Statement of Responsibility) V. Lombrado Toledano.
En la velada organizada por la Sociedad de amigos de la U.R.S.S. el día 22 de junio de 1942 ... Vicente Lombardo Toledano pronunció el discurso que contiene este folleto.- Prelim. leaf.
Soviet Union
Mexico

41602928
43021759
ocm41602928

Résumé : (Thesis) Thesis (M.A. in J. and Com.) -- University of Florida.
(Bibliography) Bibliography: leaf 109.
Manuscript copy.
Vita.
Florida
Cuba
UF

Droits : All rights reserved, Board of Trustees of the University of Florida
000577029
13908710
ADA4720

Éditeur(s) : University of Florida, Agricultural Experiment Station University of Florida, Agricultural Experiment Station
Résumé : Caption title.
Includes bibliographic references (leaf 29).
Haiti
Haiti

163577174

Éditeur(s) : Impr. centrale Impr. centrale ( Port-au-Prince )
Résumé : Errata: leaf inserted.
Haiti
United States
United States
Haiti

24112297
ocm24112297

Éditeur(s) : Socioeconomia Rural, ICTA Socioeconomía Rural, Instituto de Ciencia y Tecnología Agrícolas, Sector Público Agrícola Socioeconomia Rural, ICTA Socioeconomía Rural, Instituto de Ciencia y Tecnología Agrícolas, Sector Público Agrícola ( Guatemala C.A )
Résumé : (Bibliography) Includes bibliographical references (leaf 17).
(Statement of Responsibility) Peter E. Hildebrand.
Cover title.
"Guatemala, C.A., August, 1979."
"Prepared for presentation in the Symposium on Socio-economic Constraints to Crop Protection, IX International Congress of Plant Protection, Washington, D.C., August 5-11, 1979."
Guatemala
Guatemala
Guatemala

71507764

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Decomposition processes in tropical semi-evergreen forests are still poorly understood. The influence of soil properties and litter quality on decomposition rate was studied in two semi-evergreen forests of Guadeloupe, a forest plantation and a secondary forest, located on different soils. Leaf litter of four tree species was enclosed in litterbags for a 14-month period. Nonlinear correlations were calculated between mass loss and the concentration of major leaf components (soluble C, N, lignin, cellulose, tannins, total soluble phenols) in order to determine the best predictor of leaf litter decomposition. Soil physico-chemical properties and ratios between some of the above-mentioned litter quality parameters were also examined as mass loss predictors. In addition, non-linear correlations were calculated between mass loss and litter quality parameters, at successive periods. Litter quality was the main determinant of litter decomposition in the studied forests. Several litter quality parameters were correlated with leaf disappearance, varying according to stages of decomposition. Between 1 month and 2.5 months, the mass loss was correlated negatively with the initial phenol content and with initial lignin:N and (lignin+phenol):N ratios. From 2.5 to 5.5 months, the mass loss was correlated negatively with the initial phenol content and positively with the initial cellulose content. At later stages of decomposition (9-14 months), the mass loss was correlated negatively with the initial tannin content. Differences in soil characteristics and fauna did not seem to be enough to affect decomposition.
ISSN: 0178-2762

hal-00499535
https://hal.archives-ouvertes.fr/hal-00499535
https://hal.archives-ouvertes.fr/hal-00499535/document
https://hal.archives-ouvertes.fr/hal-00499535/file/Article_decomposition.pdf
DOI : 10.1007/s00374-002-0467-3

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Studies on the periodicity of wood formation provide essential data on tree age and factors related to the control of tree growth. The aim of this work was to investigate the cambial phenology and its relation with leaf phenology and climatic seasonality in two tropical rainforest species belonging to the genus Parkia known for having a contrasted leaf phenology. From wood samples collected at 15 day intervals from April 2009 to February 2012 in five trees of both species, we quantified cambial activity by counting layers of cells in cambial zone, enlarging cells zone and wall thickening cells zone from wood prepared anatomical micro sections. In the same time, we observed leaf shedding behaviors in the crown of the studied trees. In both species, cambial activity was significantly reduced during leafless period. However, the cambial activity of P. velutina was not affected by seasonality while in P. nitida, we found a significant positive effect of the dry season on cambial activity. This diminution of activity associated to leaf shedding occurred annually during the dry season in P. nitida whereas the trees were not synchronous in time for P. velutina. On the contrary that is often admitted, the rest cambial period can be independent of environmental restriction such as dry season. Leaf phenology remains the best proxy to estimate cambial activity.
ISSN: 0931-1890

hal-01135166
https://hal.archives-ouvertes.fr/hal-01135166
https://hal.archives-ouvertes.fr/hal-01135166/document
https://hal.archives-ouvertes.fr/hal-01135166/file/Art_Morel_al_Seasonal_variations_phenological_traits_2015.pdf
DOI : 10.1007/s00468-015-1177-4

Éditeur(s) : HAL CCSD European Geosciences Union (EGU)
Résumé :  
The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n = 81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91Mgha−1 yr−1 (mean±standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41Mgha−1 yr−1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91Mgha−1 yr−1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83Mgha−1 yr−1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40Mgha−1 yr−1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.
Biogeosciences

hal-01032140
https://hal.archives-ouvertes.fr/hal-01032140
DOI : 10.5194/bg-7-43-2010

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : We characterised the among species variability in leaf gas exchange and morphological traits under controlled conditions of seedlings of 22 tropical rainforest canopy species to understand the origin of the variability in leaf carbon isotope discrimination (Delta) among species with different growth and dynamic characteristics (successional gradient). Our results first suggest that these species pursue a consistent strategy in terms of (Delta) throughout their ontogeny (juveniles grown here versus canopy adult trees from the natural forest). Second, leaf (Delta) was negatively correlated with WUE and N, and positively correlated with gs, but among species differences in (Delta) were mainly explained by differences in WUE. Finally, species belonging to different successional groups display distinct leaf functional and morphological traits. We confirmed that fast growing early successional species maximise carbon assimilation with high stomatal conductance. In contrast, fast and slow growing late successional species are both characterised by low carbon assimilation values, but by distinct stomatal conductance and leaf morphological features. Along the successional gradient, these differences result in much lower (Delta) for the intermediate species (i.e. fast growing late successional) as compared to the two other groups.
ISSN: 1286-4560

hal-01032038
https://hal.archives-ouvertes.fr/hal-01032038
DOI : 10.1051/forest:2006101