Root Electrolyte Leakage Research Articles

Sensitivity of physiological traits to different short-term drought events and subsequent recovery at the sapling stage in European white elm (Ulmus laevis Pall.)

There is an urgent need to better understand the processes underlying trees resistance and resilience to drought as a prerequisite for adapting to climate change. In this study, the effect of different short-term drought events on the physiology of European white elm saplings, as well as the rates at which their physiological traits recover after drought were identified. Elm saplings responded sensitively to drought stress: leaf water potential, net photosynthesis and stomatal conductance were the most sensitive traits. The normalized difference vegetation index and leaf water content responded only to severe drought stress conditions. Drought triggered the conversion of soluble carbohydrates to starch in leaves but not in roots. Root function was severely damaged by drought as indicated by increased root electrolyte leakage. Tree survival and the recovery rate were significantly better under two shorter drought periods compared to one longer drought. For this reason, the precipitation pattern in models evaluating tree survival under climatic change has to be taken into account. The differences in the studied traits between surviving and dying saplings increased as drought progressed and leaf water content together with leaf reflectance indexes were identified as the best indicators for evaluating tree mortality risk. These findings are very important, as they show that these specific traits can be used to identify trees susceptible to drought in the field as they can be sensed remotely.

Acidic soil tolerance of sugarcane and <i>Erianthus</i> root assessed by cell membrane stability

Sugarcane (Saccharum spp.) growth and yield decrease in acidic soil (low pH and high Al content) conditions owing to impaired nutrient and water absorption. An efficient method to evaluate acid tolerance needs to be developed to utilize Erianthus arundinaceus to improve acid tolerance in sugarcane. Herein, we performed a root electrolyte leakage assay to quantitatively evaluate and compare the acid tolerance of the roots of sugarcane cultivar NiF8 and E. arundinaceus accession JW630 under various treatments of acid solutions in laboratory. Additionally, cellular damage of root was observed anatomically and their growth in acidic soil was verified by pot cultivation. To detect the interspecific difference in injury index of root by measuring electrolyte leakage, the following method was found suitable: initial washing for 15 min, acid stress treatment with 3% Al2(SO4)3 solution for 2 h, and leaking electrolyte from the damaged cells in ultrapure water for 2–4 h. The index was aligned with the relative growth rate (RGR) under acidic soil (pH 5.0), as E. arundinaceus with a lower index value exhibited a higher RGR. Callose, indicative of cellular damage, was deposited both after exposure to short-term and long-term acid stress in the exodermis of sugarcane, which showed higher injury index and lower RGR than those of E. arundinaceus, whereas callose deposition was not observed in E. arundinaceus even after acid stress treatments. Our results strongly suggest that the injury index measurements can be used to quantitatively evaluate differences in acid tolerance between sugarcane and Erianthus roots.

Characterization of copper-induced-release of exudates by Citrus sinensis roots and their possible roles in copper-tolerance

Copper (Cu) excess is often observed in old Citrus orchards. Little information is available on the characterization of Cu-induced-release of root exudates and their possible roles in plant Cu-tolerance. Using sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] seedlings as materials, we investigated the impacts of 0, 0.5, 25, 150, 350, 550, 1000, 2000 or 5000 μM CuCl2 (pH 4.8) on Cu uptake, root exudates [malate, citrate, total phenolics (TP), total soluble sugars (TSS) and total free amino acids (TFAA)], electrolyte leakage and malondialdehyde, and solution pH under hydroponic conditions; the time-course of root exudates and solution pH in response to Cu; and the impacts of protein synthesis and anion-channel inhibitors, and temperature on Cu-induced-secretion of root exudates and solution pH. About 70% of Cu was accumulated in 0 and 0.5 μM Cu-exposed roots, while over 97% of Cu was accumulated in ≥25 μM Cu-exposed roots. Without Cu, the seedlings could alkalize the solution pH from 4.8 to above 6.0. Cu-stimulated-secretion of root exudates elevated with the increment of Cu concentration from 0 to 1000 μM, then decreased or remained unchanged with the further increment of Cu concentration, while root electrolyte leakage and malondialdehyde (root-induced alkalization) increased (lessened) with the increment of Cu concentration from 0 to 5000 μM. Further analysis indicated that Cu-stimulated-secretion of root exudates was an energy-dependent process and could repressed by inhibitors, and that there was no discernible delay between the onset of exudate release and the addition of Cu. To conclude, both root-induced alkalization and Cu-stimulated-release of root exudates played a key role in sweet orange Cu-tolerance via increasing root Cu accumulation and reducing Cu uptake and phytotoxicity.

Tyrosine or lysine priming modulated phenolic metabolism and improved cadmium stress tolerance in mung bean (Vigna radiata L.)

Cadmium stress deleteriously affects plant growth and yield with disturbed plant metabolism. Phenylpropanoid pathway (PePP) is an important component of plant secondary metabolism known to produce nutraceutical antioxidants. We hypothesized that tyrosine (Tyr) and lysine (Lys) vary in their metabolic entry into PePP pathway and modulate it differently. Hence, a completely randomized experiment was planned with four replicates; 12 hours primed (control, hydroprimed, 0.2% Tyr, and 0.2% lysine) mungbean seeds with two stress levels (0 and 0.22 mM CdCl2). Harvests were planned at vegetative and fully mature stages of growth. Attributes like total soluble proteins, total phenolic contents, flavonoids, membrane damage characteristics, and phenolic profile were used to compare the efficacy of applications. Cadmium (0.22 mM) reduced growth in terms of leaf dry weight, leaf area, germination percentage, root vigor, shoot vigor, number of pods, and soluble proteins. Enhanced levels of malondialdehyde (MDA) and relative Root Electrolyte Leakage indicated oxidative damage in stressed plants. Other parameters of growth and yield remained ineffective with increased accumulation of phenolics and flavonoids indicative of moderate cadmium tolerance. Lys and Tyr priming improved root fresh weight, shoot length, leaf dry weight, germination percentage, root and shoot vigor, number of pods, soluble proteins, phenolics and flavonoids with reduction of MDA and root electrolyte leakage. Activity of PAL, leaf number and leaf area were exclusively increased in Tyr primed stressed plants. Tyr directly and Lys indirectly affected products of PePP with improved stress tolerance in mung bean.

Enhanced Cd-Accumulation in Typha latifolia by Interaction with Pseudomonas rhodesiae GRC140 under Axenic Hydroponic Conditions.

The Typha genus comprises plant species extensively studied for phytoremediation processes. Recently, Pseudomonas rhodesiae GRC140, an IAA-producing bacterium, was isolated from Typha latifolia roots. This bacterium stimulates the emergence of lateral roots of Arabidopsis thaliana in the presence and absence of cadmium. However, the bacterial influence on cadmium accumulation by the plant has not been determined. Moreover, the P. rhodesiae GRC140 effect in Cd phytoextraction by T. latifolia remains poorly understood. In this work, an axenic hydroponic culture of T. latifolia was established. The plants were used to evaluate the effects of cadmium stress in axenic plants and determine the effects of P. rhodesiae GRC140 and exogenous indole acetic acid (IAA) on Cd tolerance and Cd uptake by T. latifolia. Biomass production, total chlorophyll content, root electrolyte leakage, catalase activity, total glutathione, and Cd content were determined. The results showed that Cd reduces shoot biomass and increases total glutathione and Cd content in a dose-dependent manner in root tissues. Furthermore, P. rhodesiae GRC140 increased Cd translocation to the shoots, while IAA increased the Cd accumulation in plant roots, indicating that both treatments increase Cd removal by T. latifolia plants. These results indicate that axenic plants in hydroponic systems are adequate to evaluate the Cd effects in plants and suggest that T. latifolia phytoextraction abilities could be improved by P. rhodesiae GRC140 and exogenous IAA application.

Maternal drought stress on Persian oak (Quercus brantii Lindl.) affects susceptibility to single and combined drought and biotic stress in offspring

Zagros woodlands in Iran are threatened by the decline of Persian oak (Quercus brantii) trees. Although the main cause of tree mortality is drought stress, bacterial pathogens such as Brenneria goodwinii also contribute to tree dieback. Maternal effects were studied in a drought-affected environment. We investigated if the susceptibility of Q. brantii seedlings to single and combined B. goodwinii and drought stresses depends on the health status of mother trees. Plants were grown from seeds collected from non-stressed healthy and drought-stressed unhealthy trees. Root weight and belowground to aboveground weight ratios were significantly higher in offspring of unhealthy mother trees, suggesting that drought stress regulated the performance of Q. brantii in the subsequent generation. Brenneria goodwinii followed by drought had synergistic negative effects on seedlings (reduced plant growth, reduced xylem vessel size and reduced relative water content of tissues) and induced more injury (reduced leaf chlorophyll content and increased root electrolyte leakage) in offspring of unhealthy trees. Increased adaptation to drought in plants germinating from drought-stressed trees was observed and the effects persisted over the vegetative period, after the plants were rewatered. The results provide a first evidence of transgenerational plasticity in response to drought stress in trees. It is concluded that the health status of trees influences the response of offspring to combined stress.

Utilization of Tomato Landraces to Improve Seedling Performance under Salt Stress

Salt stress is considered as one of the most frequent factors limiting plant growth and productivity of crops worldwide. The aim of the study was to evaluate physiological and biochemical responses of nine diverse tomato genotypes exposed to salt stress. In this regard, four-week-old seedlings of one modern variety, five landraces, the salt-sensitive accession of ‘Ailsa Craig’, the salt-tolerant wild accession of S. pimpinellifolium ‘LA1579’, as well as the vitamin C-rich S. pennellii introgression line ‘IL12-4’, were exposed to moderate salt stress (200 mM NaCl) for 10 days. At the end of the stress treatment, agronomical traits and stress indices were evaluated, while gas exchange-related parameters, root electrolyte leakage, malondialdehyde content and ascorbic acid were also determined. All parameters were significantly affected by salt stress, but to a different extent, verifying the diverse degree of tolerance within the selected genotypes, and further highlighting the different stress-induced mechanisms. The landrace originated from ‘Santorini’ island, as well as the modern variety, which originated from traditional cultivars, demonstrated a better performance and adaptivity under moderate salt stress, accompanied by reduced lipid peroxidation and enhanced ascorbic acid content, indicating that they could be potential promising genetic material for breeding programs or as grafting rootstocks/scions.

Overwinter Storage of European Beech and Norway Spruce Planting Stock: Effect of Different Methods and Temperature Conditions

The aim of this research was to compare methods of overwinter storage of forest tree species planting stock and to specify of the optimal and the minimal temperature for freezing. Planting stock of European beech and Norway spruce were stored three times over a period of dormancy (2015/2016, 2016/2017, 2017/2018) (1) in freezers, (2) in an air-conditioned warehouse, (3) in a cave and (4) in soil (bare-rooted plants) and at a holding area (containerized plants), i.e., an open storage. During storage, the vitality of plants was determined using the root electrolyte leakage (REL) parameter, and in 2016 also by restoring growth in a sample of plants. The stored plants were always planted in a forest research plot in the spring and their basic morphological parameters and mortality were evaluated at the end of the growing season. The most suitable temperature for storage of both bare-rooted and containerized beech and spruce was in the range from −3.4 °C to −1.7 °C. The plants after overwinter storage showed no significant mortality after planting–they showed a high vitality of the fine roots and a normal increment, and were not damaged by frost, mold or other negative factors during storage.

Effects of grafting on growth, root morphology and leaf physiology of pepino (Solanum muricatum Ait.) as affected by salt stress under hydroponic conditions

In this study, grafted and ungrafted pepino (Solanum muricatum Ait.) plants were tested under different saline conditions. The nutrient solution experiment was conducted within October – November 2016, by employing the technique of Deep-Water Culture (DWC) in an entirely operated automatically climate chamber found in the Plant Physiology Laboratory of Erciyes University, Agriculture Faculty, Kayseri, Turkey. Plants were examined under three various salt levels (i.e., 1 dS m-1, 4 dS m-1 and 8 dS m-1) by growing them in a 8 liter pots loaded constantly in an aerated Hoagland solution. The study was organized with completely randomized block design through three repetitions. The climate chamber study was performed to investigate effects of salt stress on plant growth, shoot- root fresh- dry weights, photosynthesis, leaf area formation, chlorophyll content of leaf (SPAD), leaf and root electrolyte leakage, total length of root, volume of root, and diameter of root in grafted and ungrafted pepino plants. The results showed that shoot growth, root morphological and leaf physiological responses were considerably (p<0.001) influenced by various levels of salt conditions at the nutrient solution. Increased salt level of the nutrient solution decreased significantly root and shoot growth, area of leaf, photosynthetic activity of both grafted and ungrafted plants. Irrespective of being grafted, significant declines were observed in shoot fresh weight (23.6%, 52.1%), root fresh weight (24.8%, 52.8%), leaf area (21.3%, 51.9%), shoot dry weight (24.3%, 53.0%), root dry weight (15.4%, 45.1%), SPAD (5.7%, 18.7%), photosynthesis rate (24.6%, 42.1%), total root length (6.7%, 16.4%), and root volume (3.8%, 5.8%) of pepino plants under 4 dS m-1 salt applications and 8 dS m-1 salt applications, respectively. Grafting promoted growth of plant in pepino plants under both control and saline conditions, furthermore it was noticed that under saline conditions biomass production of both grafted and ungrafted ones were significantly depressed.Grafted plants produced 54.1%, 43.0% and 9.6% higher shoot fresh weight; 52.0%, 42.0% and 12.8% higher root fresh weight; 52.5%, 40.7% and 8.7% higher leaf area; 60.0%, 46.6% and 11.1% higher shoot dry weight; 68.8%, 36.0% and 29.3% higher root dry weight; 19.9%, 9.2% and 8.2% higher SPAD; 8.0%, 5.1% and 10.8% higher photosynthesis rate; 8.6%, 3.6% and 6.6% higher total root length; 3.1%, 6.7% and 2.4% higher root volume than ungrafted plants under 1 dS m-1, 4 dS m-1 and 8 dS m-1 salt applications, correspondingly. Overall, our study showed that the effectiveness of grafting with respect to expansion of plants growth and development under salinity. Grafting was demonstrated to be an effective mean to achieve this goal.

Water availability effects on germination, membrane stability and initial root growth of Agave lechuguilla and A. salmiana

Water availability during seed germination and seedling development is critical to plant development and establishment. The aim of this study was to determine the effects of four water potentials (ΨW) (−0.03, −0.48, −1.19 and −2.04 MPa) on seed germination, seedling root growth and root membrane stability of Agave lechuguilla Torr. and A. salmiana Otto ex Salm-Dyck. to explain the paradoxical situation of vegetatively propagated species producing large quantities of seeds in a dry climate. The results showed that seed water uptake and germination percentage were significantly lower at −1.19 and −2.04 MPa than at −0.03 MPa. The time to reach maximum seed germination increased at low ΨW. The final root length and root growth rate were higher in A. salmiana than in A. lechuguilla and decreased at ΨW of −1.19 and −2.04 MPa. Both Agave species increased root electrolyte leakage at ΨW of −1.19 MPa, which suggests changes in membrane integrity and stability in response to the water deficit. These germination and initial root growth responses could ensure the establishment of both Agave species during the rare periods with sufficient moisture availability and allow them to tolerate initial periods of low water availability, although with low establishment probability.

GENOTOXICITY AND ANTIOXIDANT ENZYME ACTIVITIES INDUCED BY THE CAPTAN FUNGICIDE IN THE ROOT OF BELL PEPPER (Capsicum annuum L. var. grossum L. cv. Kandil)

In this study, we investigated the toxic effects of the captan fungicide by using morphological, physiological and cytological parameters in bell pepper (Capsicum annuum L. var. grossum L. cv. Kandil) root tissue. The seeds of bell pepper were germinated in Petri dishes including different concentrations (0, 25μM, 50μM, 100μM, 150μM) of captan fungicide for 7 days. The germination rates and root lengths were significantly reduced in captan-treated seeds. All concentrations caused a significant decrease in mitotic index and increase in different types of chromosomal abnormalities such as c-mitosis and chromosome stickness in meristematic cells of bell pepper root. Captan treatment also induced oxidative stress by leading to membrane damage with an increase in root electrolyte leakage in 7 days-old bell pepper root. Catalase, glutathione reductase and total peroxidase activities increased under different concentrations as a response to oxidative stress. Our results showed that captan fungicide had negative effects on germination and growth in bell pepper seed.

Ascorbic acid of cowpea seeds under saline stress

Abstract: Salinity adversely affects plant growth and metabolism by triggering increased production of reactive oxygen species (ROS). Ascorbic acid (AsA) is known to protect organelles and cells against ROS by preventing accumulation. The objective of this study was to study the effects of AsA on cowpea beans under saline stress. Cowpea seeds of the cultivars (BRS Marataoã and Setentão) were conditioned at concentrations of 0.0 (control); 0.25; 0.50; 0.75 and 1.00 mM AsA and seeded on paper towels, moistened at saline levels of 0.0 (control); 1.5; 3.0; 4.5; 6.0 and 7.5 dS.m-1, packed in a bench germinator at 25 °C. The statistical design adopted was a completely randomized 2 × 5 × 6 factorial design (cultivar x ascorbic acid x saline levels) with four replicates of 50 seeds per treatment. The analyzed variables were percentage of germination, first germination count, germination speed index, shoot and root length, total seedling dry weight, and leaf and root electrolyte leakage. Ascorbic acid at concentrations of 0.50 mM for BRS Marataoã and 0.75 mM for the Setentão, enabled the development of more vigorous seedlings and the reduction of membrane damage caused by oxidative stress both in the absence of salt and at the saline levels tested, including the highest one.

Root system response in Argania spinosa plants under drought stress and recovery

ABSTRACTThe argane tree is a remarkable essence by its botanical interest and its socioeconomic value. It is endemic species in the southwest of Morocco, where prolonged drought stress may occur. Although its tolerance has been commonly attributed to various mechanisms at the whole plant, the root system has a main role in the whole process of adaptation. We studied in argane tree plants the change in hydraulic conductivity, electrolyte leakage in root as well as root growth under drought stress and recovery. Our findings showed that the root hydraulic conductivity (Lpr) value significantly decreased under drought stress treatment. This was associated with an increase of root electrolyte leakage, signaling the occurrence of an injury to root cell membranes. At root growth level, stressed plants managed to maintain their root elongation despite decreased root mass. After short period of rehydration, the argane tree plants exhibited a tendency of increased hydraulic conductivity during recovery after drought stress, suggesting that this root physiological response may be intimately linked to drought stress tolerance strategies. These results also could be important to contribute to selection of tolerant genotypes and develop argane tree regeneration programs in regions that suffer from lack of water.

Jasmonic and salicylic acid effects on bacterial etiolation and decline disease of creeping bentgrass

Creeping bentgrass (Agrostis stolonifera), an important turfgrass on golf course putting greens can become plagued by bacterial etiolation disease caused by Acidovorax avenae subsp. avenae (Aaa). There are no known pesticides that have been shown to be effective in managing this disease. This series of hydroponic growth chamber studies investigated whether pre-treating plants with SA or JA could be effective in reducing disease symptoms of Aaa in creeping bentgrass ‘Penn-A4’ (Aaa sensitive) and ‘Tyee’ (more tolerant). The treatments included foliar application of 10 μmol/L SA, 20 μmol/L SA, 0.5 mM JA in 0.02% ethanol and 2 mM JA in 0.02% ethanol prior to exposure to heat stress (35 °C) and optimal temperature (23 °C) with or without Aaa inoculation. Physiological measurements included turf quality (TQ), leaf and root electrolyte leakage, chlorophyll content (CHL), photochemical efficiency and root viability. No significant differences were detected in either cultivar due to chemical or heat treatment alone, which indicates chemical treatments had specific effects on plant responses to bacteria and were not confounded by plant heat stress symptoms. SA application reduced Aaa disease symptoms of both cultivars under both optimal and high temperature treatments. At both 23 °C and 35 °C, the severity of disease in plants treated with SA was less than in control plants based on all measurements in our experiment. Creeping bentgrass ‘Tyee’ treated with JA showed significantly higher TQ than control plants at 35 °C. ‘Penn-A4’ treated with JA only showed significantly higher CHL than control at 23 °C. SA and JA treatments could be viable methods to induce creeping bentgrass tolerance of bacterial pathogens; however, field testing of these methods is needed.

Why seedlings grow: influence of plant attributes

Successful forest restoration requires planting quality seedlings with optimal growth potential. Thus, nurseries need to produce seedlings with plant attributes that favor the best chance of successful establishment once they are field planted. From the mid-twentieth century on, research foresters have critically examined plant attributes that confer improved seedling growth under various restoration site conditions. This review examines the value of commonly measured seedling quality attributes (i.e., height, diameter, root mass, shoot-to-root ratio, drought resistance, freezing tolerance, nutrient status, root growth potential, and root electrolyte leakage) that have been recognized as important in explaining why seedlings with improved attributes have better growth after planting. Seedlings with plant attributes that fall within the appropriate range of values can increase the speed with which they overcome planting stress, initiate growth, and become “coupled” to the forest restoration site, thereby ensuring successful seedling establishment. Although planting high quality seedlings does not guarantee successful seedling establishment, it increases chances for successful establishment and growth.

Phytoremediation of heavy metals by Alternanthera bettzickiana: Growth and physiological response

The present study was aimed to evaluate the morphological, physiological and biochemical responses of Alternanthera Bettzickiana (Regel) G. Nicholson plant subjected to different levels of cadmium (Cd) and lead (Pb) (0, 0.5, 1.0 and 2.0mM) stress. A. bettzickiana was able to accumulate Cd and Pb in different plant parts and total uptake of both metals was higher in shoots than roots. Plant growth, biomass and photosynthetic pigments increased with increasing metal concentrations, up to 1.0mM, in soil and then decreased with higher metal levels. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased under lower metal levels (0.5 and 1.0mM) while decreased at higher metal levels (2.0mM). Leaf and root electrolyte leakage (EL), malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents decreased at lower metal levels (≤1.0mM) while increased at higher levels. The present study clearly signifies the potential of A. bettzickiana plant towards Cd and Pb tolerance and accumulation especially at lower metal levels.

Involvement of nitric oxide in the jasmonate-dependent basal defense against root-knot nematode in tomato plants.

Jasmonic acid (JA) and nitric oxide (NO) are well-characterized signaling molecules in plant defense responses. However, their roles in plant defense against root-knot nematode (RKN, Meloidogyne incognita) infection are largely unknown. In this study, we found that the transcript levels of the JA- and NO-related biosynthetic and signaling component genes were induced after RKN infection. Application of exogenous JA and sodium nitroprusside (SNP; a NO donor) significantly decreased the number of egg masses in tomato roots after RKN infection and partially alleviated RKN-induced decreases in plant fresh weight and net photosynthetic rate. These molecules also alleviated RKN-induced increases in root electrolyte leakage and membrane peroxidation. Importantly, NO scavenger partially inhibited JA-induced RKN defense. The pharmacological inhibition of JA biosynthesis significantly increased the plants’ susceptibility to RKNs, which was effectively alleviated by SNP application, showing that NO may be involved in the JA-dependent RKN defense pathway. Furthermore, both JA and SNP induced increases in protease inhibitor 2 (PI2) gene expression after RKN infestation. Silencing of PI2 compromised both JA- and SNP-induced RKN defense responses, suggesting that the PI2 gene mediates JA- and NO-induced defense against RKNs. This work will be important for deepening the understanding of the mechanisms involved in basal defense against RKN attack in plants.

Response of Hybrid Peach × Almond Trees to Increasing Rate of Soil-Applied Urea and Compost Nitrogen

ABSTRACTThe aims of the present study were to verify that high mineral N, specifically nitrate, may reduce plant growth by inducing a toxic effect on plants. GF667 plants were fertilized with urea or compost at rising rates of N (mg kg−1): 0, 200, 500, and 1000. At 8, 37, and 94 days after fertilization, plant growth, tissue N, root starch concentrations, electrolyte leakage (E. L.), superoxide dismutase (SOD), and catalase (CAT) enzymes were measured. Unlike compost, urea application promoted a linear increase of soil nitrate and ammonium during the experiment. Plant growth responded to urea-N application rates according to a second degree function with the highest plant biomass found at a urea-N rate between 200 and 500 mg N kg−1; and higher rates decreased plant growth. SOD and CAT showed no response to source and rate of N, while E. L. was higher in roots fertilized with urea-N.

Chemical and physiological responses of four Turkish red pine (Pinus brutia Ten.) provenances to cold temperature treatments

Determining the adaptability to abiotic conditions and potential establishment success of tree species needs to be conducted before attempting to use a species in large-scale afforestation programs. In this study, the chemical and physiological performance of four Turkish red pine (Pinus brutia Ten.) provenances was investigated after exposure to artificial cold temperature treatments to determine their adaptability to cold environment for potential use in afforestation programs. Seeds were sown and raised for 24, 28, and 32 weeks and exposed to decreasing temperatures in an artificial freezer. Relative electrolyte leakage, chlorophyll fluorescence, and carbohydrate concentrations were measured to determine the variability between provenances. Results showed that diameter and height growth did not vary with origin for each of the three growth stages measured. Root electrolyte leakage values differed between provenances, confirming that cold stress was effectively causing physiological damages when plants were exposed to temperature at −15 °C and below. The variability observed in the relationship between provenances and cold hardiness responses can be attributed to tree-to-tree variability within provenances and microsites conditions. There was generally no significant difference in chlorophyll fluorescence between provenances, also attributed to low genetic variation between provenances. Carbohydrate concentrations were also very variable and varied significantly among growth stages and provenances. High-altitude provenances had higher soluble carbohydrates concentrations in several cases, suggesting a relationship between altitude, soluble sugars, and cold hardiness. However, these trends were not consistent; therefore, we suggest that such hypotheses be confirmed through more comprehensive further studies.

Stress resistance levels at the time of lifting affect post-planting performance of Quercus robur seedlings

The objective of this study was to describe the physiological condition of bare-root pedunculate oak (Quercus robur L.) seedlings at the time of lifting for cold storage or planting in 1996/1997 and 1997/1998. Dormancy intensity and other physiological measurements and field performance were assessed. Heat treatments were used to assess the taproot resistance to stress using root electrolyte leakage, but the results indicated that the plants were least resistant when mostdormant. Root electrolyte leakage and root growth potential were lowest during the deep dormancy stage and increased again as shoot dormancy was released, coinciding with the period that the plants were most resistant to storage stresses. Dry weight fraction of the shoots was a good indicator of storability, but the other measures were less useful. Despite good survival rates, shoot quality was poor for seedlings lifted early (October) or late (April, May) in the lifting season.