Search results for "ecophysiology"

FRUIT PRODUCTION OF CULTIVATED CACTI: A SHORT OVERVIEW ON PLANT ECOPHYSIOLOGY AND C BUDGET

2009

Cactus pear (O. ficus-indica (L.) Mill.) fruit production: Ecophysiology, orchard and fresh-cut fruit management

2015

Cactus pear (Opuntia ficus-indica L. Mill.) is cultivated in wide range of environments with the consequence of large differences in crop potential, orchard systems and management. These differences may be related to temperature and rainfall range (water availability) but also to the day/night length and, of course, to soil characteristics. This leads to considerable variability in the field and in fruit quality. Crop value much depends in crop variability in terms of fruit size, which is the major factor for fruit price in Europe. The increase of crop value very much depends on regular cultural practices such as irrigation and fruit thinning, but it is also dependent on plant crop yield an…

The impact of winter flooding with saline water on foliar carbon uptake and the volatile fraction of leaves and fruits of lemon (Citrus limon) trees

2012

We investigated the consequences of recurrent winter flooding with saline water on a lemon (Citrus × limon (L.) Burm.f.) orchard, focussing on photosynthesis limitations and emission of secondary metabolites (isoprenoids) from leaves and fruits. Measurements were carried out immediately after flooding (December), at the end of winter (April) and after a dry summer in which plants were irrigated with optimal quality water (September). Photosynthesis was negatively affected by flooding. The effect was still visible at the end of winter, whereas the photosynthetic rate was fully recovered after summer, indicating an unexpected resilience capacity of flooded plants. Photosynthesis inhibition by…

Microscopical and Mycological Investigations on Wood of Pendunculate Oak (Quercus robur L) Relative to the Occurrence of Oak Decline

1996

Summary Microscopical studies exhibited great differences between healthy and damaged pendunculate oak trees (Quercus robur L.) relative to the state of sapwood vessels and the degree of fungal infection. In the sapwood of damaged trees deposits, discolorations and early tylosis formations were found which frequently occurred in combination with fungal infections. These results lead to the assumption that the defence reaction of the trees probably induced by fungal infection changes the structure of the tree vessels to such an extent that their water transfer function is disturbed. Some fungal genera playing an important role in the discussion of the causes of oak decline could be isolated.…

Impairment of leaf hydraulics in young plants of Citrus aurantium (sour orange) infected by Phoma tracheiphila.

2007

Phoma trachephila (Petri) Kantschaveli et Gikachvili causes dieback of several Citrus species. The impact of this fungus on leaf hydraulics was studied in Citrus aurantium L. (sour orange) with the aim of identifying the primary mechanism of damage to leaves. Leaves inoculated with a conidial suspension were measured for conductance to water vapor (gL) and specific hydraulic conductance (Kleaf) every 3 days after inoculation. The earliest symptom of infection consisted of vein chlorosis. Functional vein density (FVD) was monitored and microscopic observations were made of major vein conduits. Impairment of vein hydraulics started 25 days after inoculation with a losses of Kleaf of 40% and g…

Grain legume seed filling in relation to nitrogen acquisition: A review and prospects with particular reference to pea

2001

International audience; Seed filling depends not only on the instantaneous supply of C and N, but also on their remobilisation from vegetative organs. C supply during seed filling depends mostly on current photosynthesis, but N assimilation and N$_2$ fixation decline during seed filling, with newly acquired N generally insufficient for the high seed demand. As seeds are strong sinks for mobilised nutrients, seed growth becomes metabolically closely associated with N remobilisation. N remobilisation from vegetative tissues to filling seeds interacts with photosynthesis since it induces senescence, which reduces the seed filling period. Hence improved grain legume seed filling requires either…

Studies on the Correlation of Putrescine and Potassium Contents in the Needles of Spruce Trees

1995

Summary The correlation between the polyamine putrescine and the nutritional element potassium was examined in Picea abies trees at numerous natural stands in Germany. The amounts of potassium and putrescine in needles was analyzed and a linear negative correlation between the K + and putrescine contents was found, which is significant in the bulk of all stands as well as in subsets. The negative correlation becomes even more pronounced when only sites situated over 600 m with trees older than 60 years are included. While former investigations were concerned with experimental conditions of potassium concentrations in soil or nutrient solutions, the data presented here derive from natural ha…

Investigations on the Polyamine Content of Spruce Needles Relative to the Occurrence of Novel Forest Decline

1991

Summary Levels of free polyamines were monitored in needles of spruce trees [ Picea abies (L.) Karst.] during the course of two vegetation periods at five natural sites. The putrescine concentration in needles of damaged spruce trees was significantly higher than in needles of undamaged trees. This is e.g. impressively proved by the putrescine/spermidine-ratio. While undamaged trees show nearly similar putrescine and spermidine concentrations, damaged trees have five- to tenfold higher putrescine levels depending on the increasing state of damage. Thus, the content of putrescine in needles can be used as a qualified biochemical damage indicator of spruce trees. The physiological effects of …

Phosphoenolpyruvate Carboxylase Activity and Malate Content of Spruce Needles of Healthy and Damaged Trees at Three Mountain Sites

1991

Summary Investigations were carried out on the phosphoenolpyruvate carboxylase (PEPC) activity and the malate content in spruce trees [Picea abies (L.) Karst] at three natural sites. In needles of damaged spruce the PEPC activity is significantly higher than in needles of undamaged spruce. Therefore, the PEPC activity seems to be a biochemical damage indicator in spruce needles. The increase in PEPC activity in damaged trees is discussed as a repair mechanism to compensate the increased need of carbon skeletons by providing oxaloacetate. The malate content is enhanced in needles of severely damaged trees. An increase in malate seems to indicate senescence reactions and may be related to the…

Aridity level, rainfall pattern and soil features as key factors in germination strategies in salt-affected plant communities

2015

Abstract In arid environments, particularly in halophytic habitats, germination ecophysiology is strongly affected by environmental factors, primarily water availability, which is influenced by quantity and seasonal distribution of precipitation and soil properties. The aim of this paper was to demonstrate that water availability is essential for the control of germination and the response of seedlings growing in saline areas. With this approach, we compared the germination strategies in two Halocnemum populations with contrasting rainfall regimes and soil aridity. The germination behavior and radicle growth under various temperature regimes, light conditions and salinity levels were evalua…