Low Osmotic Potential Research Articles

Water Relations and Physiological Traits Associated with the Yield Components of Winter Wheat (Triticum aestivum L.)

Water stress in agricultural systems may occur slowly or abruptly. Plant reactions to stress differ with regard to its level and duration. The level of plant susceptibility to water deprivation primarily depends on the management of the water content and metabolism adjustments. The aim of this study was to determine the correlation between water-based plant parameters and the yield components of 90 genotypes of winter wheat (Triticum aestivum L.). Since the loss of water is frequently used as a selection criterion to assess drought tolerance, the relationships between the yield and leaf water content, osmotic potential, and gas exchange characteristics were examined. Genotypes 1, 25, 34, 36, 42, 43, 46, 57, 66, 73, and 90 showed 33–45% larger numbers of grains/plant, 19–25% higher weights of grains/plant, and 4% higher thousand grain weights compared to other genotypes. The higher values of the yield components were accompanied by 20–30% lower leaf water content, 39–52% lower osmotic potential, and 4–39% lower water use efficiency. The principal component analysis revealed that the wheat genotypes had noticeable differences in a few physiological parameters that depended on the sowing date. Electrolyte leakage showed a substantial correlation with the sowing date, suggesting that it may not be a suitable factor for the prediction of drought tolerance. The factors that distinguished the examined genotypes the most were the leaf water content, osmotic potential, and water use efficiency. In addition, a significant correlation was observed between the mentioned parameters and yield components. As a result, these parameters may be helpful in genotype characterization in relation to water stress susceptibility, offering a trustworthy plant selection test.

Water absorption from air and ammonia loss from urea fertilizers applied to grassland in southeastern United States

AbstractInformation on water absorption from the air by urea fertilizers and on NH3 loss when applied to grasslands is limited. Urea application to grassland is typically broadcast (Bcast), whereas urea‐ammonium nitrate (UAN) is applied either Bcast or in bands (dribble). This work was conducted to (1) evaluate water absorption from the air by Bcast granular urea, Bcast UAN, and dribble UAN under laboratory conditions, and (2) compare NH3 losses from Bcast urea, Bcast UAN, and dribble UAN when applied to a grassland. Six field studies were conducted from 2017 to 2019. In the laboratory, Bcast UAN exposed to 100% relative humidity absorbed water from air at a faster rate than dribble UAN and Bcast urea. In the field, all three fertilizers lost similar amounts of NH3 when applied to relatively wet soil (> −0.1 MPa). In contrast, when the fertilizers were applied to dry soil (≤ −1.2 MPa), Bcast UAN lost the most NH3 (17.3% and 19.8%) likely because of its capacity to absorb water from the air. Also, at −1.2 MPa, dribble UAN lost more NH3 than Bcast urea (15.3 vs. 10.7%, p < 0.05), probably because the low osmotic potential of UAN (−55 MPa) allowed it to absorb water from the soil at a faster rate than urea could absorb water from the air. In contrast, when the soil water potential was −5.7 MPa, dribble UAN lost less NH3 than Bcast urea (4.4 vs. 17.3%, p < 0.05), likely because the low soil water potential reduced its water absorption.

Chronic mild cadmium exposure increases the vulnerability of tomato plants to dehydration

Heavy metal contamination increases plant susceptibility to both biotic and abiotic stresses. However, the comprehensive impact of heavy metal pollution on plant hydraulics, which is crucial for plant productivity, and the interaction between heavy metal stress and environmental factors on plant health are not yet fully understood. In this study, we investigated the effects of cadmium exposure on plant-water relations and hydraulics of Solanum lycopersicum L., cultivar Piccadilly. Particular attention was given to leaf hydraulic conductance (KL) in response to cadmium pollution and dehydration.Cadmium exposure exhibited negligible impacts on tomato productivity but resulted in significant differences in pressure-volume derived traits. Leaves and roots of Cd-treated plants showed reduced wall stiffness compared to control samples. However, Cd-treated leaves had a less negative turgor loss point (Ψtlp), whereas Cd-treated roots exhibited more negative Ψtlp values due to lower osmotic potential at full turgor compared to control samples.Leaves and root cells of Cd-treated plants showed higher values of saturated water content compared to control plants, along with a distinct mineral profile between the two experimental groups. Despite similar leaf water potential thresholds for 50% and 80% loss of KL in control and cadmium-treated leaves, plants grown in cadmium-polluted soil showed higher leaf cell damages even under well watered conditions. This, in turn, affected the plant ability to recover from drought upon rehydration by compromising cell rehydration ability.Overall, the present findings suggest that under conditions of low water availability, cadmium pollution increases the risk of leaf hydraulic failure.

Germination responses of carob (Ceratonia siliqua L.) seeds to salinity and water stresses: Implications for the restoration of Mediterranean marginal lands

The iconic Mediterranean tree, Ceratonia siliqua L., holds substantial potential for restoring arid and semi-arid marginal lands. However, there is limited knowledge about the interaction of various abiotic factors and environmental stressors on seed germination of C. siliqua. Therefore, we examined the influence of salinity levels (0, 75, 150, 225 mM) and water stress using PEG6000 (−0.4, −0.8, −1.2 MPa) on C. siliqua seed germination under varying thermoperiods (15/25 °C and 25/35 °C) and photoperiods (12 hours of light and complete darkness). Our findings indicate that higher temperatures (25/35 °C) significantly reduced germination of seeds compared to lower temperatures (15/25 °C). However, the photoperiods showed no significant impact, especially under minimal salinity stress and low osmotic potentials (75 mM NaCl and −0.4 MPa PEG). In general, C. siliqua seeds exhibited enhanced performance in darkness at higher osmotic potentials, while increased stress prolonged the germination period. The dry weight of seedlings decreased with higher osmotic potential, although 75 mM NaCl promoted seedling biomass production. Our results confirm C. siliqua resilience to high salinity and moderate drought, offering practical applications for its successful reintroduction and cultivation in challenging Mediterranean environmental conditions.

Comparison of the Climate Change Tolerance of Native and Non-Native Species Used or Potentially Used as Ornamentals in Mediterranean Areas

As a consequence of climate change, temperature and rainfall regimes are being modified, threatening the survival of the current gardening concept in many areas of the world. This situation highlights the need to investigate the potential of other species, especially in more sensitive areas such as the Mediterranean Basin. The aim of this research is to study the resilience of adapted species to promote sustainable gardening. To achieve this, seven species belonging to three families (Amaranthaceae, Lamiaceae and Asteraceae) used or potentially used as ornamentals were selected to compare their tolerance at the germinative stage to different levels of temperature (10 °C to 35 °C) and water stress created by PEG 6000 (−0.10 MPa to −2.5 MPa). Germination percentage, mean germination time, base temperature, thermal time, base water potential and hydrotime were calculated. The results showed a good response to high temperature and low osmotic potential in most of the species, and germination even increased under certain stress levels. Salsola oppositifolia presented by far the best results in terms of germination under high-water-stress conditions and the second best at high temperatures. The extraordinary response of Celosia argentea, an alien species, highlighted the risk of it becoming an invasive species.

Nursery cultural practices influence morphological and physiological aspen seedling traits: implications for post-fire restoration

Aspen forests are threatened by the impacts of a changing climate and are showing large-scale mortality with meager natural regeneration to restore these loses. Therefore, there is an increasing demand for high-quality aspen seedlings to assist with forest restoration efforts. Nursery cultural practices can be used to alter aspen seedling traits to improve adaptability to dry planting conditions. In this study, the effects of container size (SC10 and D30; 158 and 490 mL, respectively) and nursery irrigation treatment (high and low irrigation; 90% and 70% container capacity, respectively) on seedling growth and a suite of morphological and physiological traits were investigated. The combination of large container size and low irrigation treatment resulted in seedlings with lowest height-to-diameter ratio and specific leaf area, which are desired traits for seedling performance on dry sites. Additionally, seedlings exposed to low irrigation conditions at the nursery stage had a lower (more negative) osmotic potential at full turgor, suggesting a higher likelihood of drought tolerance. Overall results from this study provide insight into utilizing nursery cultural practices to produce seedlings with target characteristics that may ultimately lead to establishment on harsh, dry planting sites in large-scale reforestation projects.

Strategies of NHX antiporters to deal with salt stress

The adverse effects of salinity on plant growth are generally associated with the low osmotic potential of the soil solution and the high level of sodium toxicity (and chlorine toxicity for some species) which cause multiple perturbations on plant metabolism, growth, and development at the molecular, biochemical and physiological levels. The vacuolar NHX and plasma membrane SOS antiporters mediate cation and proton exchange across the tonoplast and plasma membrane, respectively. The SOS transporters allow the excretion of Na+ from the cytoplasm to the outside environment and alternatively, NHXs provide Na+ transport from the cytoplasm to the vacuole. Cellular ion homeostasis is an essential phenomenon for all organisms. Most cells manage to maintain a high level of potassium and a low level of sodium in the cytoplasm through the coordination and regulation of different transporters and channels instead of the NHX-type vacuolar antiport. In this article, some important mechanisms in the regulation of ionic ions such as Na+. will be discussed.

Divergence in cold tolerance promotes niche differentiation between diploid and polyploid kiwifruits along an altitudinal gradient in Southwest China

Polyploidization is hypothesized to improve the freezing resistance of plants in cold regions. However, adaptive strategies and key physiological mechanisms involved in the freezing resistant ability of polyploids remain unclear. In Actinidia chinensis (kiwifruits), the tetraploids and hexaploids occupy higher altitude habitats with colder climates than the diploids, providing a study system to investigate mechanisms responsible for differentiation in freezing resistance between cytotypes. We characterized environmental conditions of their natural distribution areas, and measured leaf‐level traits of cold damages and water relations at typical sites of each cytotype along an altitudinal gradient. Polyploids showed lower semi‐lethal temperature (LT50) than ice nucleation temperature (INT), reflecting a tolerance strategy to cope with freezing events in the plateau regions. More negative turgor loss points and larger cell elastic modulus of polyploids could help to alleviate damages from freezing‐induced cell dehydration, thus strengthening their tolerance to lower subzero temperatures (lower LT50). The increased supercooling capacity of polyploids (lower INT) might correlate with less extracellular ice formation due to lower osmotic potential at full turgor, apoplastic water fraction and tissue capacitance. Our study uncovers a greater cold tolerance in polyploid kiwifruits than diploids, and suggests the potential linkage between freezing tolerance and water relations. Taken together, such a divergence in stress resistance may underlie the niche shift of polyploid plants towards harsh environments.

Ambient aerosols increase stomatal transpiration and conductance of hydroponic sunflowers by extending the hydraulic system to the leaf surface

IntroductionMany atmospheric aerosols are hygroscopic and play an important role in cloud formation. Similarly, aerosols become sites of micro-condensation when they deposit to the upper and lower surfaces of leaves. Deposited salts, in particular can trigger condensation at humidities considerably below atmospheric saturation, according to their hygroscopicity and the relative humidity within the leaf boundary layer. Salt induced water potential gradients and the resulting dynamics of concentrated salt solutions can be expected to affect plant water relations.MethodsHydroponic sunflowers were grown in filtered (FA) and unfiltered, ambient air (AA). Sap flow was measured for 18 days and several indicators of incipient drought stress were studied.ResultsAt 2% difference in mean vapor pressure deficit (D), AA sunflowers had 49% higher mean transpiration rates, lower osmotic potential, higher proline concentrations, and different tracer transport patterns in the leaf compared to FA sunflowers. Aerosols increased plant conductance particularly at low D.DiscussionThe proposed mechanism is that thin aqueous films of salt solutions from deliquescent deposited aerosols enter into stomata and cause an extension of the hydraulic system. This hydraulic connection leads – parallel to stomatal water vapor transpiration – to wick-like stomatal loss of liquid water and to a higher impact of D on plant water loss. Due to ample water supply by hydroponic cultivation, AA plants thrived as well as FA plants, but under more challenging conditions, aerosol deposits may make plants more susceptible to drought stress.

Magnesium supplementation alleviates drought damage during vegetative stage of soybean plants.

Our working hypothesis was that magnesium (Mg) supplementation modulates plant performance under low water availability and improves drought tolerance in soybean genotypes. Plants of Bônus 8579, M8808 and TMG1180 genotypes were grown under field conditions and subjected to three water stress treatments (control, moderate and severe stress) and three Mg levels [0.9 (low), 1.3 (adequate) and 1.7 cmolc dm-³ (supplementation)]. After 28 days of drought imposition, the growth parameters, osmotic potential, relative water content, leaf succulence, Mg content and photosynthetic pigments were assessed. In general, drought drastically decreased the growth in all genotypes, and the reductions were intensified from moderate to severe stress. Under adequate Mg supply, TMG1180 was the most drought-tolerant genotype among the soybean plants, but Mg supplementation did not improve its tolerance. Conversely, although the M8808 genotype displayed inexpressive responses to drought under adequate Mg, the Mg-supplemented plants were found to have surprisingly better growth performance under stress compared to Bônus 8579 and TMG1180, irrespective of drought regime. The improved growth of high Mg-treated M8808-stressed plants correlated with low osmotic potential and increased relative water content, as well as shoot Mg accumulation, resulting in increased photosynthetic pigments and culminating in the highest drought tolerance. The results clearly indicate that Mg supplementation is a potential tool for alleviating water stress in M8808 soybean plants. Our findings suggest that the enhanced Mg-induced plant acclimation resulted from increased water content in plant tissues and strategic regulation of Mg content and photosynthetic pigments.

Adaptability and Germination Characteristics of Volunteer Wheat in China's Main Wheat-Producing Areas.

Volunteer wheat commonly occurs and spreads rapidly in the main wheat-producing areas of China, seriously impacting cultivated wheat production. Limited information is currently available regarding the adaptability and germination traits of volunteer wheat. Therefore, this study's aim was to evaluate the effects of environmental conditions on the germination and emergence of volunteer wheat seeds through laboratory experiments. The results showed that the germination percentages and viability of volunteer wheat were significantly higher than those of cultivated wheat at a low temperature of 5 °C, and they were lower than those of cultivated wheat at high temperatures of above 30 °C. Compared to cultivated wheat, volunteer wheat was able to tolerate higher salinity and lower osmotic potential, especially long-dormancy volunteer wheat. The secondary germination ability of volunteer wheat was higher than that of cultivated wheat after water immersion. Furthermore, volunteer wheat could not emerge normally when the seeding depth was greater than 8 cm, and the emergence ability of the volunteer wheat was weaker than that of the cultivated wheats when the seeding depth was 4-8 cm, which indicates that the deep tillage of cultivated land could effectively prevent the spread of volunteer wheat. This study revealed differences in the germination characteristics of volunteer wheat and cultivated wheat under the influence of different environmental factors, which provides a basis for future studies concerning the control of volunteer wheat.

The Influence of the Osmotic Potential on Evapotranspiration

Climate change is expected to affect the quality of soil and water, resulting in a significant impact on soil water balance in various regions around the world. Soil water potential plays a significant role in influencing evapotranspiration (ET), which is a crucial component of the soil water balance. The matric potential and the osmotic potential are the main components of the soil water potential. The osmotic potential is particularly important in dry soils, salt-affected soils, coastal lands, or when low-quality water is utilized for irrigation. Despite its importance, the impact of osmotic potential on ET has not been well-studied compared to other factors. Therefore, we conducted a study to investigate the impact of osmotic potential on ET from small-scale lab lysimeters planted with grass and equipped with scales and data loggers connected to computers. To create different osmotic potential levels, we irrigated the lysimeters with two different water qualities: distilled water and 4.79 dS.m−1 NaCl solution. The lysimeters were kept in well-watered conditions, and daily ET was monitored. Our results indicate a strong correlation between osmotic potential and ET. After three months of applying the treatments, the lysimeters with lower osmotic potential had a 39% reduction in cumulative ET compared to those irrigated with distilled water. Moreover, the osmotic stress affected plant health, leading to a notable decrease in the leaf area index and exerting a significant influence on evapotranspiration partitioning components, including transpiration and evaporation.

Drought shortens cotton fiber length by inhibiting biosynthesis, remodeling and loosening of the primary cell wall

Drought could severely impair the formation of cotton fiber length, yet the underlying mechanism is not fully understood. Here, the effects of drought on cotton fiber elongation processes including primary cell wall biosynthesis, remodeling and loosening and osmolyte accumulation were investigated from transcriptomic and physiological levels by using two upland cotton cultivars (Dexiamian 1 and Yuzaomian 9110). The results showed that the cotton fiber elongation was significantly stunted under drought, and the biggest reduction in fiber length appeared at 10 days post anthesis. The total osmolytes concentration of cotton fiber sap was increased by drought via promoting the accumulation of malate and K+, which was favorable to fiber elongation. Whilst the biosynthesis of fiber primary cell wall components including pectin, hemicellulose and cellulose was inhibited under drought by suppressing the expression of galacturonosyltransferase (GhGAUT) and galacturonosyltransferase-like (GhGATL), xylosyltransferase (GhXXT), and cellulose synthase (GhCesA) respectively, leading to reduced fiber cell wall biomass. Meanwhile, drought restricted the remodeling and loosening of fiber primary cell wall by suppressing the expression of genes related to primary cell wall decomposition including pectin methylesterase (GhPME), xyloglucan endotransglucosylase/hydrolase (GhXTH), and endoglucanase (GhEG), and α-expansin (GhEXPA). Taken together, it is concluded that the shortened fiber length induced by drought was caused by restricted primary fiber cell wall biosynthesis, remodeling, and loosening but not the lowered osmotic potential. Overall, our work provides new insights into understanding the mechanisms by which drought shortens cotton fiber length.

Active Sugar Accumulation and Water Status of Watermelon Fruit Grown under Different Nutrient Concentrations in Hydroponic Culture

We investigated sugar (solute) accumulation in watermelon [Citrullus lanatus (Thunb.) Matsum. et Nakai] fruits at the immature stage. Watermelon plants were grown hydroponically in a nutrient solution with an electric conductivity (EC) of 1.2 S⋅m−1 (EC 1.2 regime); then, fruits were harvested 21 days after anthesis. The flesh of each fruit was divided into seven different parts to measure the sugar concentration and water status. The results indicated that the sugar concentration was higher in the center of the fruit flesh than in the other parts, such as around the pericarp. Moreover, the lowest osmotic potential was observed in the center of the fruit flesh, indicating solute accumulation. Concurrently, when the transport of photosynthates in the fruit was investigated using the 13CO2 isotope, the active solute accumulation in the center of the fruit flesh was observed, supporting the observed sugar accumulation in this part. Consequently, this active solute accumulation and distribution occurred in the center of the watermelon fruit, as demonstrated by the data of osmotic pressure and sugar concentration and supported by the observed active photosynthate accumulation. Additionally, we investigated these measurements by increasing the nutrient solution concentration 14 days after anthesis. As a result, fruit growth was slightly inhibited using the EC 3.0 regime, and 13C translocation was also inhibited in the fruit, especially in its center. Even though the sugar concentration and osmotic pressure of the fruit flesh were not clearly affected by high nutrient solution concentrations, the cell turgor of the central flesh of the fruit grown using the EC 2.0 and 3.0 regimes was lower than that of the fruit grown using the EC 1.2 regime. Treatments with higher nutrient concentrations might have negative effects on immature watermelon fruits.

Orchard Net Covers Improve Resistance to Cherry Cracking Disorder.

Orchard net cover improves plant physiology, yield and fruit quality, pest and disease control, and anticipates fruit ripening. Moreover, this crop technology has been used to reduce natural cherry cracking (NCC). This is a serious physiological disorder that cracks the epidermis, the hypodermis, and the storage parenchyma layers of the fruit due to rainfall events near the harvest and it is related to low fruit osmotic potential and/or high fruit water permeability. This work aims to study the effect of orchard net cover on sweet cherry trees, cv. Early Bigi, in two harvesting years (2019 and 2021). The NCC, the induced cracking index (CI), and the cracking type incidence were determined. In addition, epicuticular and intra-cuticular wax content, biometric and physicochemical parameters were also evaluated. Net cover reduced the natural cracking index by 40%. High fruit weight values were observed in covered trees comparing to the control ones, with increases of 45% and 13%, in 2019 and 2021, respectively. A positive correlation was observed between CI and total soluble solids and a negative correlation between CI and wax content. Therefore, with forecasts of worsening heavy precipitation events near harvest, protecting cherry trees with nets will increase resistance to fruit cracking.

Applications of Xerophytophysiology and Signal Transduction in Plant Production—Flower Qualities in Eustoma grandiflorum Were Improved by Sub-Irrigation

Relatively mild xerophytic or hardening treatments can induce healthy development of plants. In the present study, as one of xerophytophysiological applications, sub-irrigation was applied to a flower plant of Eustoma grandiflorum to confirm whether the sub-irrigation improved flowering quality in addition to plant growth and physiology. As shown by the results, long-term sub-irrigation induced osmotic adjustment, with osmolyte concentration increasing 32.8 osmol m−3 (p ≤ 0.01), improved leaf photosynthetic activities, with more than 10% (p ≤ 0.05) increase in photosynthetic capacity, and promoted plant growth, with a shoot biomass increase by 27.5% (p ≤ 0.01) and a root increase by 50.5% (p ≤ 0.01). These improvements were attributed to turgor maintenance and cell water re-compartmentation into the symplasm, which were both the consequence of osmotic adjustment. The lower osmotic potential and lower relative leaf water potential at incipient plasmolysis suggested that plants in sub-irrigation plots might be more resistant to environmental stresses. Sub-irrigation also improved flower quality shown by increased anthocyanin concentration (16% up, p ≤ 0.01). Flower quality improvement might be attributed to up-regulation of the PAL gene, which could catalyze the synthesis of anthocyanins. PAL gene up-regulation might be associated with a concentration increase in salicylic acid (SA), which was suggested as a plant hormone for signaling. Sub-irrigation also affected the flower opening and closing oscillations with less changed opening size or oscillation amplitude. We adopted mathematical models and thoroughly analyzed dynamic changes in photosynthesis, plant growth, and flower opening oscillations. In conclusion, sub-irrigation was a feasible practice and could be used in E. grandiflorum culture to improve plant growth and flower opening quality.

Modeling the influence of temperature, salt and osmotic stresses on seed germination and survival capacity of Stipa tenacissima L.

This work stands for a modelling approach to identify the cardinal temperature of germination of Stipa tenacissima L., its capacity to recover and its adaptation potential considering dormancy and viability after exposure to salinity and drought. Seed traits characterised before germination were tested. The seeds were incubated at temperatures of 10 to 30 °C and low osmotic potentials were induced using sodium chloride (NaCl) or polyethylene glycol (PEG 6000) solutions of 0 to −1.6 MPa. The capacity of seeds to recover and remain viable under stress conditions was quantified. Our results proved that the seed yields and sizes were uniform. The analysis of cardinal temperature by thermal time model exhibited an optimal germination temperature (T o) of about 19 °C, a base temperature (T b) of 0.6 °C and a ceiling temperature (T c) of 31 °C at 0 MPa. The base water potential Ψb (50) values ranged between −0.83 and −1.54 MPa and between −0.97 and −2.27 MPa for osmotic and salt stresses, at 30 °C and 20 °C, respectively. In conclusion, the species showed a lower seed recruitment related to a low drought tolerance (drought tolerance index = −0.5 MPa), To requirement and threshold sensitivity. Under salt stress, S. tenacissima used osmotic adjustment in order to germinate in a lower osmotic potential.

EFFECT OF DIFFERENT SEED PRIMING METHODS ON RICE (ORYZA SATIVA L.) CV SUKKHA DHAN-3

Priming is control hydration of seeds in a solution of low osmotic potential to initiate germination to ensure uniform and efficient germination of seed. Erratic seed germination is a major problem of rice production that causes poor crop establishment, crops susceptible to abiotic stress, and insect, and disease infestation resulting in poor yield. Different seed priming methods can be a useful technology for farmers to solve this problem. To ascertain the impact of different seed priming methods an experiment was carried out in the Horticulture Lab of Campus of Live Sciences, Dang with 12 treatment combinations with 3 replications laid out in factorial Completely Randomized Design (CRD). The treatments entailed; hydro-priming in tap water, hydro-priming in distilled water, polyethylene glycol PEG 6000 (5%), Ascorbic acid (2%), KNO3 (2%), Salicylic acid (2%), ZnSO4 (5%), NaCl (5%), MgCl2 (5%), CaCl2 (2%), Gibberellin (300ppm) and No priming as Control. The seeds were soaked for 24 hours in treatments followed by 12 hours of drying. The Priming treatment with ZnSO4 (5%) showed the most promising results for germination percentage (82%), root: shoot ratio (1.91), germination rate (5.47), germination energy (76.67) and seedling vigor. ZnSO4 (5%) was followed by PEG 6000(5%), distilled water, and KNO3 (2%). Beside this, root length (9.94cm) was found highest in PEG 6000(5%) followed by ZnSO4 (5%), KNO3 (2%), and distilled water. Shoot length (8.003cm), Speed of germination (90.38), and germination rate index (76.67) were highest in KNO3 (2%). This study concludes that ZnSO4 (5%) showed the best result among all treatments and all the priming treatments showed better performance except Salicylic acid (2%) and No priming (Control). The study concluded that besides Salicylic acid (2%), seed priming was found to be more effective than no priming and in enhancing seed performance by activating overall metabolic processes of seed.

A heat shock transcription factor gene (HaHSFA1) from a desert shrub, Haloxylon ammodendron, elevates salt tolerance in Arabidopsis thaliana

Haloxylon ammodendron is a typical desert xerophyte with worthy genetic resources, therefore, it is necessary to explore the resistance genes of H. ammodendron , and to improve the stress tolerance of other plant species through genetic engineering. In this study, a heat shock transcription factor gene, HaHSFA1 , was firstly cloned from H. ammodendron and overexpressed in Arabidopsis thaliana . The sensitivity of transgenic plants to exogenous ABA, osmotic stress and salt stress were analyzed; the effects of overexpression of HaHSFA1 in Arabidopsis on salt tolerance were deeply investigated. The results indicated that overexpression of HaHSFA1 increased chlorophyll content in Arabidopsis, and the growth of plants was promoted. The leaf soluble sugar and proline contents in OE lines were significantly increased compared with those in WT. OE lines maintained lower osmotic potential and higher shoot water content. Overexpression of HaHSFA1 in Arabidopsis also enhanced antioxidant activity, which may be important for protecting plasma membrane integrity in cells. Overexpression of HaHSFA1 in Arabidopsis improved root activity and increased selective absorption and transport capacity for K + over Na + , which was of great significance to reduce the toxic effect of Na + . This study indicated that overexpression of HaHSFA1 from H. ammodendron significantly elevates the salt tolerance of Arabidopsis, and HaHSFA1 has potential application values in improving abiotic stress tolerance in crops by genetic engineering. • HaHSFA1 was firstly cloned from a desert shrub, Haloxylon ammodendron . • Overexpression of HaHSFA1 enhanced osmotic adjustment and ROS scavenging ability in Arabidopsis. • Overexpression of HaHSFA1 maintained higher selectivity of absorption and transport for K + over Na + in Arabidopsis.

Testing the association of relative growth rate and adaptation to climate across natural ecotypes of Arabidopsis.

Ecophysiologists have reported a range of relationships, including intrinsic trade-offs across and within species between plant relative growth rate in high resource conditions (RGR) vs adaptation to tolerate cold or arid climates, arising from trait-based mechanisms. Few studies have considered ecotypes within a species, in which the lack of a trade-off would contribute to a wide species range and resilience to climate change. For 15 ecotypes of Arabidopsis thaliana in a common garden we tested for associations between RGR vs adaptation to cold or dry native climates and assessed hypotheses for its mediation by 15 functional traits. Ecotypes native to warmer, drier climates had higher leaf density, leaf mass per area, root mass fraction, nitrogen per leaf area and carbon isotope ratio, and lower osmotic potential at full turgor. Relative growth rate was statistically independent of the climate of the ecotype native range and of individual functional traits. The decoupling of RGR and cold or drought adaptation in Arabidopsis is consistent with multiple stress resistance and avoidance mechanisms for ecotypic climate adaptation and would contribute to the species' wide geographic range and resilience as the climate changes.