Search results for "Season"
showing 10 items of 1002 documents
Comparison of growth potentials of epicormic shoots of nectarine trees grown on size-controlling and vigorous rootstocks
2006
SummaryThe vegetative performance of four nectarine tree scion/rootstock combinations, with varying growth capacities, were analysed in the Spring after the canopy:root ratio was dramatically reduced by severe pruning in the dormant season. We anticipated that severe pruning and reduction of the shoot:root ratio would mitigate known root water supply limitations related to the various rootstocks and determine if other factors associated with the rootstocks would control the rates of epicormic shoot growth. The trees used in this field experiment were 3 years-old, with ‘May Fire’ nectarine grafted onto four different rootstocks: ‘Nemaguard’ (a vigorous seed-propagated control, P. persica P. …
Productivity and canopy modification of Medicago arborea as affected by defoliation management and genotype in a Mediterranean environment
2004
Medicago arborea is one of the most potentially valuable fodder shrubs in a Mediterranean environment because of its high preference by small ruminants and its nutritive value. Edible biomass production is affected by agronomic and environmental factors. A study, carried out in an inland area of Sicily in the growing seasons of 1994/95, 1995/96 and 1996/97, evaluated the forage production and canopy modification in a M. arborea plantation after (i) commencing defoliation 1 or 2 years after transplanting and (ii) defoliating only in autumn (A), only in early summer (S) or in both seasons (A and S). Six clones derived from five different Mediterranean populations were used. Plant age at the f…
A simple geometrical model for analysing the spectral response of a citrus canopy using satellite images
1990
Abstract A simple geometrical model has been proposed for a citrus canopy. We assume the citrus orchard to be a lattice structure, with the trees positioned at its points and where the composite-scene reflectance is the sum of the reflectance of its individual components as weighted by their respective surfaces within a unit area. The model has been used to analyse the citrus spectral response obtained from Landsat-5 TM images for winter and summer, where the status of the orchard is different. The correlations between spectral and geometrical data show the influence of per cent crop cover, shadows and background in the composite scene reflectance. We conclude that the summer images could b…
Crop Load and Rootstock Influence on Dry Matter Partitioning in Trees of Early and Late Ripening Peach Cultivars
2002
ADDITIONAL INDEX WORDS. vigor, starch, fruit size, Prunus persica ABSTRACT. Effect of crop load on dry matter partitioning was studied on 3-year-old peach ((Prunus persica (L.) Batsch (Peach Group)) trees of the early ripening 'Early May Crest' (EMC) grafted on 'GF677' and Penta (Prunus domestica L.) rootstock and the late ripening 'Flaminia' grafted on 'GF677' rootstock ((Prunus persica x Prunus dulcis (Mill.) D. A. Webb) and grown outdoors in 230-L containers, for 2 years. Fruit thinning was carried out 10 days after fruit set to produce different crop loads. Trees were sampled destructively throughout two growing seasons and divided into above- ground and root components, for dry matter …
Comparison of Crop Trait Retrieval Strategies Using UAV-Based VNIR Hyperspectral Imaging.
2021
Hyperspectral cameras onboard unmanned aerial vehicles (UAVs) have recently emerged for monitoring crop traits at the sub-field scale. Different physical, statistical, and hybrid methods for crop trait retrieval have been developed. However, spectra collected from UAVs can be confounded by various issues, including illumination variation throughout the crop growing season, the effect of which on the retrieval performance is not well understood at present. In this study, four retrieval methods are compared, in terms of retrieving the leaf area index (LAI), fractional vegetation cover (fCover), and canopy chlorophyll content (CCC) of potato plants over an agricultural field for six dates duri…
WITHIN TREE AND ORCHARD VARIABILITY OF SILVER KING PEACH (PRUNUS PERSICA (L.) BATSCH) FRUIT QUALITY
2012
The variability of crop quality accounts for most of seasonal variation of farmers’ incomes, since fruit value mostlydepends on its size and overall quality. Canopy architecture and orchard lay-out are mainly responsible for within tree environment and allocation, which in turn, account for fruit quality and its variability. Little is known about within tree and between trees variability resulting from different planting and training systems. A positive relationship has been measured in peach between PAR and TEAC (Motisi et al., 2005; Scalzo et al., 2005; Motisi et al., 2008). This study was carried out to measure within tree and orchard variability of fruits of the early ripening ‘Silver K…
Dynamics and Predictability of a Heavy Dry-Season Precipitation Event over West Africa—Sensitivity Experiments with a Global Model
2009
Abstract In January 2002 the Cape Verde region in tropical West Africa was hit by an exceptionally heavy precipitation event. Rain rates of up to 116 mm (48 h)−1 caused harmful impacts on the local population. The rainfall was triggered by a series of two upper-level disturbances penetrating from the extratropics to the West African coast. This study investigates the dynamics and predictability of this event on the basis of simulations with the global model Global Model Europe (GME) of the German Weather Service [i.e., Deutscher Wetterdienst (DWD)] initialized by the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data. Free forecasts satisfactorily reproduce the upper-l…
Comparative responses of ‘Gala’ and ‘Fuji’ apple trees to deficit irrigation: Placement versus volume effects
2012
Aims: Climate, soil water potential (SWP), leaf relative water content (RWC), stomatal conductance (gs), fruit and shoot growth, and carbohydrate levels were monitored during the 2008 and 2009 growing seasons to study the responses of 'Gala' and 'Fuji' apple trees to irrigation placement or volume. Methods: Three irrigation treatments were imposed, conventional irrigation (CI), partial root-zone drying (PRD, 50% of CI water on one side of the root-zone, which was alternated periodically), and continuous deficit irrigation (DI, 50% of CI water on both sides of the root-zone). Results: After each irrigation season, DI generated twice the soil water deficit (SWDint) than PRD (average of dry an…
Exposure to moderate concentrations of tropospheric ozone impairs tree stomatal response to carbon dioxide.
2011
With rising concentrations of both atmospheric carbon dioxide (CO(2)) and tropospheric ozone (O(3)), it is important to better understand the interacting effects of these two trace gases on plant physiology affecting land-atmosphere gas exchange. We investigated the effect of growth under elevated CO(2) and O(3), singly and in combination, on the primary short-term stomatal response to CO(2) concentration in paper birch at the Aspen FACE experiment. Leaves from trees grown in elevated CO(2) and/or O(3) exhibited weaker short-term responses of stomatal conductance to both an increase and a decrease in CO(2) concentration from current ambient level. The impairement of the stomatal CO(2) respo…
Estimating the age and season-at-death of ungulates from the analysis of archaeological dental cementum: Recent improvements and perspectives from th…
2018
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