Home About us Contact
|
Home About us Contact | ||
|
|
||
Phenological Stages (phenological + stage)
Selected AbstractsPhenological stages of willow (Salix)ANNALS OF APPLIED BIOLOGY, Issue 3 2010Margaret M. Saska The practice of uniform recording of biological plant growth stages or events has long been practiced in agricultural production. In this study the BBCH (Biologishe Bundesanstalt, Bundessortenamt and CHemical Industry) code has been applied to four precocious species of willows to define growth stages important to this group. The studied taxa represent varieties of potential importance in the Floral Industry. A new BBCH code is proposed where the annual cycle of willows is divided into clearly recognisable and easily distinguishable developmental phases which include eight principal stages, 30 secondary stages and six mesostages. Photographs illustrate the physical appearance of select stages. This proposed BBCH code shows a unified approach which may be applied to a large number of Salix species. [source] Consequences for a host,parasitoid interaction of host-plant aggregation, isolation, and phenologyECOLOGICAL ENTOMOLOGY, Issue 4 2007ADAM J. VANBERGEN Abstract 1.,Spatial habitat structure can influence the likelihood of patch colonisation by dispersing individuals, and this likelihood may differ according to trophic position, potentially leading to a refuge from parasitism for hosts. 2.,Whether habitat patch size, isolation, and host-plant heterogeneity differentially affected host and parasitoid abundance, and parasitism rates was tested using a tri-trophic thistle,herbivore,parasitoid system. 3.,Cirsium palustre thistles (n= 240) were transplanted in 24 blocks replicated in two sites, creating a range of habitat patch sizes at increasing distance from a pre-existing source population. Plant architecture and phenological stage were measured for each plant and the numbers of the herbivore Tephritis conura and parasitoid Pteromalus elevatus recorded. 4.,Mean herbivore numbers per plant increased with host-plant density per patch, but parasitoid numbers and parasitism rates were unaffected. Patch distance from the source population did not influence insect abundance or parasitism rates. Parasitoid abundance was positively correlated with host insect number, and parasitism rates were negatively density dependent. Host-plant phenological stage was positively correlated with herbivore and parasitoid abundance, and parasitism rates at both patch and host-plant scales. 5.,The differential response between herbivore and parasitoid to host-plant density did not lead to a spatial refuge but may have contributed to the observed parasitism rates being negatively density dependent. Heterogeneity in patch quality, mediated by variation in host-plant phenology, was more important than spatial habitat structure for both the herbivore and parasitoid populations, and for parasitism rates. [source] Chemical mediation and niche partitioning in non-pollinating fig-wasp communitiesJOURNAL OF ANIMAL ECOLOGY, Issue 2 2007MAGALI PROFFIT Summary 1The parasitic chalcidoid wasps associated with the species-specific and obligatory pollination mutualisms between Ficus spp. and their agaonid wasp pollinators provide a good model to study the functional organization of communities. 2However, communities of non-pollinating fig wasps (NPFWs) remain little characterized, and their functioning and evolutionary dynamics are still poorly understood. 3We studied the communities of NPFWs associated with the monoecious F. racemosa and the dioecious F. hispida. Associated with these two fig species are a total of seven wasp species belonging to three genera. These species present contrasts in life history traits and in timing of oviposition. The species studied are thus broadly representative of the communities of NPFWs associated specifically with fig,pollinator mutualisms. 4In our study systems, there is temporal segregation of oviposition time among members of NPFW communities. 5We tested the role of volatile chemicals in the attraction of NPFWs associated with these two fig species, and tried to determine if chemical mediation can explain the organization of the communities. 6We conducted odour choice tests using a Y-tube olfactometer. All the NPFWs studied were shown to use volatile chemicals produced by the fig to locate their host. Furthermore, the signals used by each species depended on the phenological stage of the fig they exploit. 7Results demonstrated that the pattern of oviposition results from the utilization of volatile signals produced by figs that vary in their composition at different stages of fig development. Thus, chemical mediation allows resource partitioning in the NPFW communities associated with fig,pollinator mutualisms, and suggests hypotheses to explain coexistence in other parasite communities. [source] Evaporative enrichment and time lags between ,18O of leaf water and organic pools in a pine standPLANT CELL & ENVIRONMENT, Issue 5 2007ROMAIN L. BARNARD ABSTRACT Understanding ecosystem water fluxes has gained increasing attention, as climate scenarios predict a drier environment for many parts of the world. Evaporative enrichment of 18O (,18O) of leaf water and subsequent enrichment of plant organic matter can be used to characterize environmental and physiological factors that control evaporation, based on a recently established mechanistic model. In a Pinus sylvestris forest, we measured the dynamics of oxygen isotopic composition (,18O) every 6 h for 4 d in atmospheric water vapour, xylem sap, leaf water and water-soluble organic matter in current (N) and previous year (N-1) needles, phloem sap, together with leaf gas exchange for pooled N and N-1 needles, and relevant micrometeorological variables. Leaf water ,18O showed strong diel periodicity, while ,18O in atmospheric water vapour and in xylem sap showed little variation. The ,18O was consistently lower for N than for N-1 needles, possibly related to phenological stage. Modelled leaf water ,18O showed good agreement with measured values when applying a non-steady state evaporative enrichment model including a Péclet effect. We determined the time lags between ,18O signals from leaf water to water-soluble foliar organic matter and to phloem sap at different locations down the trunk, which clearly demonstrated the relevance of considering these time-lag effects for carbon transport, source-sink and carbon flux partitioning studies. [source] A host-pathogen simulation model: powdery mildew of grapevinePLANT PATHOLOGY, Issue 3 2008A. Calonnec An epidemiological model simulating the growth of a single grapevine stock coupled to the dispersal and disease dynamics of the airborne conidia of the powdery mildew pathogen Erysiphe necator was developed. The model input variables were either climatic (temperature, wind speed and direction) or related to the pathogen (location and onset of primary infection). The environmental input variables dictated plant growth and pathogen spread (latent period, infection, lesion growth, conidial spore production and release). Input parameters characterized the crop production system, the growth conditions and the epidemiological characteristics of the pathogen. Output described, at each time step, number, age and pattern of healthy and infected organs, infected and infectious leaf area and aerial density of spores released. Validation of the model was achieved by comparing model output with experimental data for epidemics initiated at different times of host growth. Epidemic behaviour for two contrasting years of crop development and 7 phenological stages at the time of primary infection (PI) was examined. For PI occurring at day 115 a vine with late budbreak (1998) showed 58% of primary leaves diseased at flowering compared with only 19% for a vine with early budbreak (2003). Depending on the phenological stage at PI (1,4 leaves), the proportion of diseased primary leaves decreased from 42% to 6% at flowering. Simulations suggested that differences resulted from the interplay between the timing of the first sporulation event, the phenological stage at the time of initial infection, and the age structure and spatial distribution of the leaf population. [source] Sexual dimorphism and seasonal changes of leaf gas exchange in the dioecious tree Ilex paraguariensis grown in two contrasted cultivation typesANNALS OF APPLIED BIOLOGY, Issue 2 2009M. Rakocevic Abstract Yerba maté (Ilex paraguariensis, Aquifoliaceae) is a subtropical, evergreen, dioecious, South American tree. In one preliminary study, it was observed that the functional strategy of yerba mate females, aiming to finish reproductive process, was increased transpiration relative to photosynthetic rates compared with males, on self-shaded leaves. We hypothesised that the long-term gas exchange response of males and females can evolve independently of phenological stage and cultivation type. In this spirit, the primary aim of the study was to analyse the physiological sexual dimorphism of this species, evaluating fluctuations of gas exchanges related to microclimate and phenological stages. A field study was conducted on adult plants of yerba maté cultivated in monoculture (MO) and in forest understorey (FUS), and measurements carried out in situ on microclimate and leaf gas exchange parameters. The photosynthetic photon flux density that was attained at leaf level in FUS was reduced roughly 10-fold compared with that in MO. Various leaf age populations were observed during a 2-year period at 2-month intervals and grouped into four categories: young, young-fully-expanded, fully-expanded and old. Young and young-fully-expanded leaves were the most active in photosynthesis. Leaves of female plants showed greater photosynthetic rate than those of male plants, which was expressed on all leaf age categories in MO, but only during vegetative stages previous to flowering and fruit ripening. The photosynthesis of young-fully-expanded leaves of females grown in FUS was superior to males but only during winter growth pause. The stomatal conductance differed in relation to cultivation type and leaf age but did not show the sexual differentiation. Physiological sexual dimorphism in yerba mate is shown to be plastic, responding to environmental conditions. The cost associated to the reproduction of yerba maté could be most easily met showing physiological differentiation of both sexes. A higher reproductive investment of females might be compensated for by exhibiting greater leaf photosynthesis than males that occurs in vegetative stages that precede flowering and fruit ripening. [source] Early-Season Headspace Volatiles from Apple and Their Effect on the Apple Blossom Weevil Anthonomus pomorumCHEMISTRY & BIODIVERSITY, Issue 9 2010Rafal Piskorski Abstract Apple volatiles emitted at early phenological stages are little investigated, although they may influence behavior of early-season pests. The apple blossom weevil Anthonomus pomorum is a herbivore pest of orchards in Europe. It colonizes apple trees in early season and oviposits into developing flower buds, often leading to economic damage. Using in situ radial diffusive sampling and thermal desorption, followed by GC/MS analysis, headspace volatiles from apple twigs with flower buds at three early phenological tree stages were identified and quantified. The volatile blend consisted of 13,compounds for the first, and increased to 15 compounds for the third phenological stage sampled. These blends included benzenoids, terpenes, and derivatives of fatty acids. A recombined synthetic blend served as the odor source in a still-air dual-choice olfactometer bioassay, in which individual male and female weevils were tested. Results from this behavioral test document an attraction of both sexes to odors of their host plant, suggesting that apple volatiles emitted in early season serve as olfactory cues for host location of A. pomorum in the field. [source] Essential oil composition of Prasium majus L. from GreeceFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2007A. Basta Abstract The essential oils from the aerial parts of Prasium majus (Labiatae), collected in two phenological stages in Greece, were analysed by GC,MS. Thirty-two compounds were identified, representing 99.8,99.9% of the total oils. The major constituents in sample A were 1-octen-3-ol (20.7%), , -pinene (14.7%) and linalool (13.8%), while those of sample B were dehydro-aromadendrene (31.8%), caryophyllene oxide (13.7%) and 1-octen-3-ol (12.4%). Copyright © 2007 John Wiley & Sons, Ltd. [source] Chemical variability of Artemisia vulgaris L. essential oils originated from the Mediterranean area of France and CroatiaFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2003I. Jerkovic Abstract The essential oils of Artemisia vulgaris L. originating from France and Croatia were subjected to detailed GC,MS analysis in order to determine possible similarities and differences between them and their chemical compositions, depending on the stage of development. Plant materials were collected in Provence (France) and Dalmatia (Croatia) at four different stages of development: vegetative (June), buds (July), ,owering (August) and seeding (September). Comparison of the chemical composition and content, depending on phenological stages in both localities, shows qualitative similarity, but also the noticeable difference in the amounts of most components. First, the chemical composition of main compounds is very different; Croatian oils are rich in hydrocarbons, which are absent or present in low amounts in French oils. Also, with regard to the yield of essential oils, the yields from Croatian oils were higher (0.09,0.61%) than these from French oil (0.04,0.15%) at each development stage, respectively. Copyright © 2003 John Wiley & Sons, Ltd. [source] Localities and seasonal variations in the chemical composition of essential oils of Satureja montana L. and S. cuneifolia TenFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2001M. Milos Abstract The essential oils of Satureja montana L. and Satureja cuneifolia Ten. were subjected to detailed GC,MS analysis in order to determine possible similarities between them and also the differences in their chemical compositions, depending on the locality and the stage of development. The plant materials were collected prior to, during and after flowering from three different locations in the central part of Dalmatia (Croatia). For both plants the qualitative composition of the components appeared to be constant in three phenological stages and in three different localities. However, considerable differences were found to exist in the amounts of several compounds. Copyright © 2001 John Wiley & Sons, Ltd. [source] Lack of Interaction between Extreme High-Temperature Events at Vegetative and Reproductive Growth Stages in WheatJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2003B. Wollenweber Abstract Increased climatic variability and more frequent episodes of extreme conditions may result in crops being exposed to more than one extreme temperature event in a single growing season and could decrease crop yields to the same extent as changes in mean temperature. The developmental stage of the crop exposed to increased temperatures will determine the severity of possible damage experienced by the plant. It is not known whether or not the damaging effects of heat episodes occurring at different phenological stages are additive. In the present study, the interaction of high-temperature events applied at the stages of double ridges and anthesis in Triticum aestivum (L.) cv. Chablis was investigated. Biomass accumulation of control plants and that of plants experiencing high temperatures during the double-ridge stage were similar and were reduced by 40 % when plants were subjected to a heat event at anthesis. Grain number on the main and side tillers declined by 41 %, and individual grain weight declined by 45 % with heat stress applied at the double-ridge stage and anthesis or at anthesis alone. The harvest index was reduced from 0.53 to 0.33. Nitrogen contents in leaves were reduced by 10 % at the double-ridge stage and by 25 % at anthesis. The maximum rates of CO2 assimilation increased with heat stress at the double-ridge stage and higher rates were maintained throughout the growing season. The results clearly indicate that an extreme heat event at the double-ridge stage does not affect subsequent growth or the response of wheat to heat stress at anthesis. [source] The influence of management regime and altitude on the population structure of Succisapratensis: implications for vegetation monitoringJOURNAL OF APPLIED ECOLOGY, Issue 4 2001Christoph Bühler Summary 1,Environmental change and land use may alter the vegetation typical of wetland habitats. However, commonly used techniques for vegetation monitoring that are based on species composition are often not suitable to detect gradual changes in the structure of vegetation at an early stage. In this study we tested if this methodical deficiency could be overcome by observation of the stage structure of a perennial target species. 2,We studied the density and frequency distribution of four phenological stages of the perennial plant Succisapratensis in 24 calcareous fens in eastern Switzerland. These fens differed in management type (mowing, cattle-grazing) and altitude (low, medium, high). Among grazed fens, the intensity of management was quantified by direct observation. Species composition and canopy structure of the plant community surrounding S. pratensis were also measured. 3,High altitude had a positive effect on the density of adult plants of S. pratensis only in mown fens, whereas in grazed fens adult density was highest at medium altitude. 4,Local densities of seedlings and vegetative adults within a fen were higher in mown than in grazed fens, and lower in fens of the lowest altitude level than of the two higher ones. However, there were no differences in the relative proportions of all four phenological stages among main factors except that significantly fewer seedlings occurred in fens of the lowest altitude level. 5,It is the intensity rather than the mere type of management regime that is crucial for shaping populations of S. pratensis: for grazed fens, there is a negative relationship between intensity of grazing and density of adult plants of S. pratensis. Moreover, the number, the relative proportion of seedlings and the seed-set are all negatively correlated with grazing intensity. 6,The species composition of the plant community, but not its physical structure, was significantly related to the relative proportion of seedlings of S. pratensis, which supports the indicator qualities of the target species. 7,Monitoring the population structure of one or several target species provides important indicator information about the stability of a whole plant community. For the target-species approach we propose to use characteristic but frequently and steadily occurring species instead of rare or endangered ones. [source] A host-pathogen simulation model: powdery mildew of grapevinePLANT PATHOLOGY, Issue 3 2008A. Calonnec An epidemiological model simulating the growth of a single grapevine stock coupled to the dispersal and disease dynamics of the airborne conidia of the powdery mildew pathogen Erysiphe necator was developed. The model input variables were either climatic (temperature, wind speed and direction) or related to the pathogen (location and onset of primary infection). The environmental input variables dictated plant growth and pathogen spread (latent period, infection, lesion growth, conidial spore production and release). Input parameters characterized the crop production system, the growth conditions and the epidemiological characteristics of the pathogen. Output described, at each time step, number, age and pattern of healthy and infected organs, infected and infectious leaf area and aerial density of spores released. Validation of the model was achieved by comparing model output with experimental data for epidemics initiated at different times of host growth. Epidemic behaviour for two contrasting years of crop development and 7 phenological stages at the time of primary infection (PI) was examined. For PI occurring at day 115 a vine with late budbreak (1998) showed 58% of primary leaves diseased at flowering compared with only 19% for a vine with early budbreak (2003). Depending on the phenological stage at PI (1,4 leaves), the proportion of diseased primary leaves decreased from 42% to 6% at flowering. Simulations suggested that differences resulted from the interplay between the timing of the first sporulation event, the phenological stage at the time of initial infection, and the age structure and spatial distribution of the leaf population. [source] Allometric growth relationships of East Africa highland bananas (Musa AAA-EAHB) cv. Kisansa and MbwazirumeANNALS OF APPLIED BIOLOGY, Issue 3 2009K. Nyombi Abstract Highland bananas are an important staple food in East Africa, but there is little information on their physiology and growth patterns. This makes it difficult to identify opportunities for yield improvement. We studied allometric relationships by evaluating different phenological stages of highland banana growth for use in growth assessment, understanding banana crop physiology and yield prediction. Pared corms of uniform size (cv. Kisansa) were planted in a pest-free field in Kawanda (central Uganda), supplied with fertilizers and irrigated during dry periods. In addition, tissue-cultured plants (cv. Kisansa) were planted in an adjacent field and in Ntungamo (southwest Uganda), with various nutrient addition treatments (of N, P, K, Mg, S, Zn, B and Mo). Plant height, girth at base, number of functional leaves and phenological stages were monitored monthly. Destructive sampling allowed derivation of allometric relationships to describe leaf area and biomass distribution in plants throughout the growth cycle. Individual leaf area was estimated as LA (m2) = length (m) × maximum lamina width (m) × 0.68. Total plant leaf area (TLA) was estimated as the product of the measured middle leaf area (MLA) and the number of functional leaves. MLA was estimated as MLA (m2) = ,0.404 + 0.381 height (m) + 0.411 girth (m). A light extinction coefficient (k = 0.7) was estimated from photosynthetically active radiation measurements in a 1.0 m grid over the entire day. The dominant dry matter (DM) sinks changed from leaves at 1118 °C days (47% of DM) and 1518 °C days (46% of DM), to the stem at 2125 °C days (43% of DM) and 3383 °C days (58% of DM), and finally to the bunch at harvest (4326 °C days) with 53% of DM. The allometric relationship between above-ground biomass (AGB in kg DM) and girth (cm) during the vegetative phase followed a power function, AGB = 0.0001 (girth)2.35 (R2 = 0.99), but followed exponential functions at flowering, AGB = 0.325 e0.036(girth) (R2 = 0.79) and at harvest, AGB = 0.069 e0.068(girth) (R2 = 0.96). Girth at flowering was a good parameter for predicting yields with R2 = 0.7 (cv. Mbwazirume) and R2 = 0.57 (cv. Kisansa) obtained between actual and predicted bunch weights. This article shows that allometric relationship can be derived and used to assess biomass production and for developing banana growth models, which can help breeders and agronomists to further exploit the crop's potential. [source] Sexual dimorphism and seasonal changes of leaf gas exchange in the dioecious tree Ilex paraguariensis grown in two contrasted cultivation typesANNALS OF APPLIED BIOLOGY, Issue 2 2009M. Rakocevic Abstract Yerba maté (Ilex paraguariensis, Aquifoliaceae) is a subtropical, evergreen, dioecious, South American tree. In one preliminary study, it was observed that the functional strategy of yerba mate females, aiming to finish reproductive process, was increased transpiration relative to photosynthetic rates compared with males, on self-shaded leaves. We hypothesised that the long-term gas exchange response of males and females can evolve independently of phenological stage and cultivation type. In this spirit, the primary aim of the study was to analyse the physiological sexual dimorphism of this species, evaluating fluctuations of gas exchanges related to microclimate and phenological stages. A field study was conducted on adult plants of yerba maté cultivated in monoculture (MO) and in forest understorey (FUS), and measurements carried out in situ on microclimate and leaf gas exchange parameters. The photosynthetic photon flux density that was attained at leaf level in FUS was reduced roughly 10-fold compared with that in MO. Various leaf age populations were observed during a 2-year period at 2-month intervals and grouped into four categories: young, young-fully-expanded, fully-expanded and old. Young and young-fully-expanded leaves were the most active in photosynthesis. Leaves of female plants showed greater photosynthetic rate than those of male plants, which was expressed on all leaf age categories in MO, but only during vegetative stages previous to flowering and fruit ripening. The photosynthesis of young-fully-expanded leaves of females grown in FUS was superior to males but only during winter growth pause. The stomatal conductance differed in relation to cultivation type and leaf age but did not show the sexual differentiation. Physiological sexual dimorphism in yerba mate is shown to be plastic, responding to environmental conditions. The cost associated to the reproduction of yerba maté could be most easily met showing physiological differentiation of both sexes. A higher reproductive investment of females might be compensated for by exhibiting greater leaf photosynthesis than males that occurs in vegetative stages that precede flowering and fruit ripening. [source] Use of stomatal conductance and pre-dawn water potential to classify terroir for the grape variety KékfrankosAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2009Zs. ZSÓFI Abstract Background and Aims:, A 3-year study was carried out in order to evaluate the ecophysiology, yield and quality characteristics of Vitis vinifera L. cv. Kékfrankos (syn. Limberger) at Eger-Nagyeged hill (steep slope) and at Eger-K,lyuktet, (flat) vineyard sites located in the Eger wine region, Hungary. The aim of this paper was to analyse the effect of ,vintage' and ,terroir' on the seasonal changes of Kékfrankos ecophysiology and its possible relationship with yield and wine composition. Methods and Results:, Grapevine physiological responses (midday- and pre-dawn water potential, pressure,volume analysis and gas-exchange), growing stages, yield and wine composition of each vineyard were studied. Lower grapevine water supply was detected at Eger-Nagyeged hill in each season due to its steep slope and soil characteristics. Pressure-volume curves indicated that there was no osmotic adjustment in the leaves of this variety. Higher osmotic concentration was measured at turgor loss and full turgor in the leaves of the unstressed vineyard (Eger-K,lyuktet,) presumably due to higher photosynthetic activity. Differences in soil water content of the vineyards resulted in a slightly altered cell wall elasticity. Stomatal conductance, transpiration rate and photosynthetic production per unit leaf area were affected by water availability. Lower yield in Eger-Nagyeged hill was partly associated with decreased photosynthetic production of the canopy. Improved wine quality of Eger-Nagyeged hill was due to moderate water stress which induced higher concentration of anthocyanins and phenolics in the berries. The duration of the phenological stages was dependent on vintage temperature characteristics rather than on vineyard site. Conclusion:, There was a close relationship between environmental conditions, Kékfrankos gas-exchange, water relations, yield and wine composition. Water deficit plays an important role in creating a terroir effect, resulting in decreased yield, better sun exposure of leaves and clusters and thus higher concentration of phenolics and anthocyanins. Although quality is mainly influenced by vintage differences, vineyard characteristics are able to buffer unfavourable vintage effects even within a small wine region. Significance of the Study:, Stomatal conductance, pre-dawn water potential and climatic data may be reliable parameters for terroir classification, although variety,terroir interactions must always be considered. [source] Early-Season Headspace Volatiles from Apple and Their Effect on the Apple Blossom Weevil Anthonomus pomorumCHEMISTRY & BIODIVERSITY, Issue 9 2010Rafal Piskorski Abstract Apple volatiles emitted at early phenological stages are little investigated, although they may influence behavior of early-season pests. The apple blossom weevil Anthonomus pomorum is a herbivore pest of orchards in Europe. It colonizes apple trees in early season and oviposits into developing flower buds, often leading to economic damage. Using in situ radial diffusive sampling and thermal desorption, followed by GC/MS analysis, headspace volatiles from apple twigs with flower buds at three early phenological tree stages were identified and quantified. The volatile blend consisted of 13,compounds for the first, and increased to 15 compounds for the third phenological stage sampled. These blends included benzenoids, terpenes, and derivatives of fatty acids. A recombined synthetic blend served as the odor source in a still-air dual-choice olfactometer bioassay, in which individual male and female weevils were tested. Results from this behavioral test document an attraction of both sexes to odors of their host plant, suggesting that apple volatiles emitted in early season serve as olfactory cues for host location of A. pomorum in the field. [source] | |||||||||||||