Search results for "Drought stre"
showing 10 items of 21 documents
Leaf starch and nutrient responses to stem girdling and drought stress with respect to understanding HLB (greening) symptoms in citrus
2016
The most important problem in world citrus production is the bacterial disease Huanglongbing (HLB; greening) which is caused by a phloem-limited bacterium that is vectored by a phloem-feeding psyllid. The earliest visible symptoms of HLB in leaves are an asymmetrical chlorosis referred to as "blotchy mottle", thought to be from starch accumulation from a phloem dysfunction and a decline in root health. We tested the hypothesis that such visible symptoms are not unique to HLB by stemgirdling two year-old seedling trees of 'Cleopatra' mandarin and 'Swingle' citrumelo rootstocks in the greenhouse. Girdling induced a 4-fold greater starch concentration in leaves on well-watered trees while star…
Arabidopsis mutant dnd2 exhibits increased auxin and abscisic acid content and reduced stomatal conductance
2019
Arabidopsis thaliana cyclic nucleotide-gated ion channel gene 4 (AtCNGC4) loss-of-function mutant dnd2 exhibits elevated accumulation of salicylic acid (SA), dwarfed morphology, reduced hypersensitive response (HR), altered disease resistance and spontaneous lesions on plant leaves. An orthologous barley mutant, nec1, has been reported to over-accumulate indole-3-acetic acid (IAA) and to exhibit changes in stomatal regulation in response to exogenous auxin. Here we show that the Arabidopsis dnd2 over-accumulates both IAA and abscisic acid (ABA) and displays related phenotypic and physiological changes, such as, reduced stomatal size, higher stomatal density and stomatal index. dnd2 showed i…
Water status and gas exchange of pistachio trees under different irrigation levels
2017
The aim of this study was to investigate the physiological responses of pistachio trees to varying water supply in the attempt to identify reliable parameters to manage irrigation. Three different irrigation regimes were applied to 25-year-old pistachio trees of cultivar 'Bianca' on P. terebinthus rootstock. Midday stem water potential (ΨSWP), leaf relative water content (RWC), light-saturated net CO2assimilation (An), stomatal conductance (gs), and ambient conditions were monitored throughout the season, and light response curves of net photosynthesis were constructed. To reflect tree water status, trees were separated into three classes of ΨSWP, no deficit (ΨSWP> -1.5 MPa), mild defici…
Recovery from water stress in laurel plants: influence of short term potassium fertilization
2013
Plant xylem hydraulic conductance varies with changes in sap solute concentrations, particularly potassium, a phenomenon known as 'ionic effect'. In well-watered Laurus nobilis plants, short term potassium fertilization increased xylem sap potassium concentration, resulting in an increase in plant hydraulic conductance (Kplant), leaf-specific conductivity of the shoot (kshoot) and transpiration rate (Eplant). The ionic effect is enhanced in embolized stems, where it can compensate the cavitation-induced loss of hydraulic conductance. The aim of this work was to test if water-stressed potassium-starved laurel plants could recover earlier from stress when irrigated with a potassium solution i…
Water recycling in leaves of Lithops (Aizoaceae)
2016
Lithops plants consist of a pair of succulent leaves inserted on a short stem; each growing season young leaves develop in a cavity formed between the older pair. Young leaves can take up water from the older pair allowing the plant to maintain growth and leaf expansion even without external supply of water. Recycling water between vegetative organs is one of the possible adaptation strategies of plants under drought stress, but it had never been demonstrated experimentally in Lithops. The methodology used to verify the existence of water redistribution from old leaves to young leaves was fluorescence microscopy, using two dyes to follow the water pathway inside the plant: Sulforhodamine G …
Some morphological, anatomical, physiological responses of different olive cultivars to high temperatures and drought stress
2004
The aim of this work is to find relationships between morphology and physiology in three different olive cultivars: Biancolilla, Cerasuola and Nocellara del Belice, when plants were subjected to high temperature and drought. These cultivars are estensively used in Sicily for productive purposes. The results about ultrastructural and physiological studies on shoot growth, leaf anatomy, chloroplast ultrastructure and oxygen production, indicate that Biancolilla is the cultivar in which the studied traits showed fewer changes and can be considered to have the best tolerance to both high temperatures and water deficit. In the other hand, the morphological and physiological characteristics studi…
Morpho-physiologic traits in two sage taxa grown under different irrigation regime
2017
Sage is an important aromatic crop, extensively cultivated worldwide. Drought stress affects yield and composition of secondary metabolites such as fatty acids, essential oils, antioxidants, changing the essential oil composition profile with respect to the ISO 9909 standard. Drought tolerance may differ among genotypes, so we compared the response of Salvia officinalis L. and S. officinalis cv. ‘Maxima’ grown under two different irrigation regimes to highlight differences in leaf growth, water potential, gas exchange and essential oil composition. Potted plants were grown in the greenhouse at 100% or 50% of field water capacity for three months. Monthly measurements of 3rd node leaf length…
Carbohydrate and nutritional responses to stem girdling and drought stress with respect to understanding symptoms of Huanglongbing (HLB) in Citrus
2013
The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle”, thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-yr-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 d, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought stressed trees. Starc…
Drought Stress Memory at the Plant Cycle Level: A Review
2021
International audience; Plants are sessile organisms whose survival depends on their strategy to cope with dynamic, stressful conditions. It is urgent to improve the ability of crops to adapt to recurrent stresses in order to alleviate the negative impacts on their productivity. Although our knowledge of plant adaptation to drought has been extensively enhanced during the last decades, recent studies have tackled plant responses to recurrent stresses. The present review synthesizes the major findings from studies addressing plant responses to multiple drought events, and demonstrates the ability of plants to memorize drought stress. Stress memory is described as a priming effect allowing a …
Spatio‐temporal patterns of tree growth as related to carbon isotope fractionation in European forests under changing climate
2019
Aim The aim was to decipher Europe‐wide spatio‐temporal patterns of forest growth dynamics and their associations with carbon isotope fractionation processes inferred from tree rings as modulated by climate warming. Location Europe and North Africa (30‒70° N, 10° W‒35° E). Time period 1901‒2003. Major taxa studied Temperate and Euro‐Siberian trees. Methods We characterize changes in the relationship between tree growth and carbon isotope fractionation over the 20th century using a European network consisting of 20 site chronologies. Using indexed tree‐ring widths (TRWi), we assess shifts in the temporal coherence of radial growth across sites (synchrony) for five forest ecosystems (Atlantic…