Root Water Content Research Articles

PHYSIOLOGICAL ANSWERS to METAL TRIGGERED EFFECTS in CROPS

Environmental pollution is one of the most important concerns for today's people. The increasing population growth in the world, together with the industrial revolution and its side effects, brings along the risk of reaching healthy food for every newborn and existing population. Contamination and/or accumulation of heavy metals, known as the source of oxidative stress, in foodstuffs and the environment directly affects human health. Since plants are often the first recipients of heavy metals from different environments (such as air, water and soil), it is not surprising that this results in scary scenarios for all living organisms. Therefore, to determine and dispose of the possible downsides in human diet which relates to heavy metals, we examined whether physiological parameters are reliable indicators of oxidative stress in different crop plants. Either with single or combined CdCl2 and PbCl2 treatments, germination percentage, root and shoot lengths and water contents were measured in the roots and shoots of Triticum aestivum cv. Gerek and Hordeum vulgare cv. Çıldır varieties in this study. According to obtained results, it is concluded that heavy metal treatments trigger the oxidative stress in plants, as all parameters measured are dramatically decreased.

Response of Prosopis farcta to gradually increased soil copper and cadmium levels based on an integrated investigation

The impact of gradually increased soil levels of copper (Cu) and cadmium (Cd) on the medicinal plant, Prosopis farcta, irrigated with metal-enriched water was determined. Plants were treated with 2.54, 5.08, 10.16, and 20.32 µg mL−1 for Cu2+ and 6.13, 12.26, 24.52, and 49 µg mL−1 for Cd2+. The rate of phytoremediation was measured by bioconcentration factor (BCF) and the relative bioconcentration factor (RBCF). The movement of metal ions from roots to shoots was calculated as the Translocation Factor (TF). The exposure of plants to Cd or Cu decreased plant growth and increased Cd and Cu concentration in their shoots and roots. The weight of both shoots and roots decreased linearly with the increase of Cu and Cd contents in roots and shoots. Cd was more toxic than Cu as expected. The water content of shoots and roots decreased linearly as heavy metal levels increased. Prosopis farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils but was more capable for transporting Cd from roots to shoots rather than Cu although more Cu is taken up by roots. Prosopis farcta is a natural accumulator of Cu and Cd and can be used in phytoremediation. CONCISE NOVEL ASPECTS OF THIS STUDY This is the first report to show that the medicinal plant Prosopis farcta is an accumulator for Cu and Cd. This was determined by gradual addition of the metals to the soil via irrigation by heavy metal-polluted water which can provide an opportunity for the plant to develop a metal-resistance mechanism. Choosing suitable plant species for heavy metal accumulation is a critical step for successful phytoremediation of heavy metal pollutants. CORE IDEAS Prosopis farcta is of interest as a medicinal plant. P. farcta can take up Cu and Cd in both Cu- and Cd-contaminated soils. P. farcta transports more Cd from roots to shoots but more Cu is taken up.

Abscisic acid signaling reduced transpiration flow, regulated Na+ ion homeostasis and antioxidant enzyme activities to induce salinity tolerance in wheat (Triticum aestivum L.) seedlings

Salinity, one of the catastrophic abiotic stresses that uces wheat production around the globe. Abscisic acid (ABA) is a stress phytohormone as a signaling molecule that led us to investigate its potential to improve morpho-physiological characteristics, antioxidant metabolism, and ion homeostasis in wheat ( Triticum aestivum L.) seedlings grown under salinity stress (0, 50, and 100 mM NaCl). The findings suggested that salt-induced toxicity significantly ( P < 0.05) damaged root morphological characteristics, plant growth, photosynthetic pigments, and water contents, while trigger the oxidative injury, Na + ion accumulation and uptake in wheat leaf and root tissues with the increasing NaCl concentration in the nutrient media. However, root-zone supply of ABA (0, 5, and 10 μ M) prominently alleviated salt induced phytotoxicity. The 10 μ M concentration of ABA promoted shoot (81.7%) and root (102.1%) dry weight, root length (38.2%), Chl. a (65.3%), Chl. b (149.0%), carotenoids (95.7%) and membrane damage (36.7%) when NaCl was added at 100 mM, relative to the corresponding treatment without ABA. Moreover, ABA (10 μ M) supply decreased Na + ion uptake (root to leaf) due to reduced transpiration rate (81.1%), and thereby ameliorated oxidative injury by ucing leaf malondialdehyde (MDA) and H 2 O 2 contents by 36.8% and 29.9%, respectively, at 100 mM NaCl stress, relative to the similar treatment without ABA. In addition, the activities of catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) were upregulated by 143.9%, 20.2%, and 19.5% in leaves and by 144.9%, 23.4% and 41.1% in roots respectively, with 10 μ M ABA application under 100 mM salinity stress, compa to the 100 mM NaCl treatment without ABA. Conclusively, this study proposed that root-zone ABA application promoted salinity tolerance in wheat seedlings and could be a practical approach for wheat production in salt-affected regions to ensure food security. • Na + ion uptake was increased by wheat tissues under salinity stress. • Abscisic acid (ABA) alleviated salt injury by promoting growth and physiology. • ABA reduced Na+ uptake and accumulation by ucing transpirational flow. • ABA regulated antioxidant metabolism in wheat tissues exposed to salinity stress.

Drying of fibrous roots strengthens the negative power relation between biomechanical properties and diameter

AimsTest the effects of root drying on biomechanical properties of fibrous roots.MethodsTensile strength and Young’s modulus of Festuca arundinacea roots were tested after full hydration and during progressive drying. Root diameter, water loss, and water content were measured for all treatments.ResultsHydrated roots showed weak relations between biomechanical properties and diameter. After only 30 min air-drying, both tensile strength and Young’s modulus increased significantly in thin roots (< 1 mm) and after 60 min drying, both strength and Young’s modulus showed a negative power relation with root diameter. The maximum strength and Young’s modulus values recorded after 60 min drying were respectively three- and four-times greater than in hydrated roots. Strength and Young’s modulus increased rapidly when water content dropped below 0.70 g g−1. These biomechanical changes were the result of root diameter shrinkage of up to 50% after 60 min drying, driven by water loss of up to 0.7 g g−1.ConclusionsStrength and Young’s modulus largely increased with root drying. We suggest controlling root moisture and testing fully hydrated roots as standard protocol, given that slope instability is generally caused by heavy rainfall events and loss of matric suction.

Beet Molasses Enhance Salinity Tolerance in Thymus serpyllum—A Study under Greenhouse Condition

The growing demand for Thymus serpyllum biomass to produce drugs, cosmetics and spices necessitates the search for innovative methods mitigating the negative effects of environmental stressors in order to improve its yield under unfavorable conditions. Due to the exposure of plants to salinity stress (SS), we investigated the effect of sugar beet molasses (SBM) on the growth and biochemical parameters related to plants’ response to SS. Wild thyme plants were treated for 5 weeks to sodium chloride and 3% molasses solution using two modes of application (soil irrigation or foliar sprays). Plants irrigated by SBM showed slighter stem growth inhibition than control plants, high stress tolerance index and maintained a constant root water content under salt stress. Moreover plants treated with 100 mM NaCl and soil-applied SBM had lower lipid peroxidation level, showed lower POD activity, higher total soluble protein content and maintained a more even free amino acids level, compared to the control treatments. The concentration of potassium ions was higher in the case of plant roots irrigation with sugar beet molasses compared to control plants. In this experiment, most of the growth and biochemical parameters from foliar molasses-sprayed plants did not differ significantly from the control. We provided evidence that soil-applied SBM beneficially changed the plant’s biochemical response to salt stress. On the basis of the obtained results, we conclude that this soil amendment contributes to the strengthening of plant protection against this harmful environmental factor.

Comparative studies on the stress responses of two Bupleurum (Apiaceae) species in support of conservation programmes

Bupleurum tenuissimum is a rare species in Spain, which became extinct in recent decades in many localities, including protected areas. In the study area, the 'Albufera' Natural Park (SE Spain), the species was present in Limonietalia grasslands, a priority and endangered habitat, but has not been observed in the last 40 years. At present, it is included in conservation programmes aimed at its reintroduction in this territory. This study's primary objective was to establish the limits of tolerance of this species to salt and water stress under controlled greenhouse conditions. A congeneric species, B. fruticousm, was included as comparative material to get insights into its stress response mechanisms. Analysis of changes in growth parameters (stem length, number of leaves, root length, fresh weight and water content of roots and leaves) in response to the applied stress treatments confirmed that B. tenuissimum behaves as a facultative (moderate) halophyte susceptible to drought stress, whereas B. fruticosum is not severely affected by water stress but is sensitive to salinity, even at low NaCl concentrations. The stress-induced changes in several biochemical parameters (contents of photosynthetic pigments, ions, osmolytes, oxidative stress markers, and non-enzymatic antioxidant compounds, and specific activities of relevant antioxidant enzymes) explained the differential behaviour of the investigated Bupleurum species. In addition to the novelty of these findings in a genus that has rarely been studied from this perspective, these results will be relevant for implementing and managing B. tenuissimum conservation programmes, guiding the selection of reintroduction sites. The study also provides valuable information on the stress tolerance of B. fruticosum, with great potential for the ecological restoration of Mediterranean dry forest vegetation and riparian thickets.

Physiological and Biochemical Effects of Cd Stress in Thlaspi Arvense L-A Non-Accumulator of Metals.

The field pennycress (Thlaspi arvense L.) is a sensitive non-accumulator of metals. The main objective of the present work was to evaluate the effects of Cd stress in T. arvense using a physiological approach. Four-week-old plants were exposed to increasing concentrations of Cd (0, 10, 50 and 100μM Cd(NO3)2) for 14days. Plants were harvested at days 0, 3, 7 and 14 to assess the following parameters: shoot and root length and fresh weight; osmolality and conductivity in leaves; chlorophyll a and b contents and photosynthetic efficiency in leaves (young and expanded); water content, Cd accumulation and nutrient imbalances in leaves (young and expanded) and roots. Thlaspi arvense presented a reduction of 27% in the length of roots exposed to 100μM Cd, and in plants exposed to 50 and 100μM Cd, a reduction in the fresh weight of both shoots (53 and 58%, respectively) and roots (58 and 63%, respectively) was observed. In general, in plants exposed to the highest concentrations of Cd, a decrease in leaves osmolality and membrane permeability and in water content of both roots and leaves were observed, as well as several nutrient imbalances. As for the photosynthetic parameters, young and expanded leaves responded differently to Cd stress. Exposed young leaves presented no alterations in photosynthetic efficiency or chlorophyll contents, while expanded leaves of 100μM Cd-treated plants showed a reduction of up to 67% in chlorophyll contents and a concomitant reduction of 30% in photosynthetic efficiency. Overall, Cd-induced senescence in the non-accumulator plant T. arvense exposed to high concentrations of Cd, which was measured as a decrease in several physiological and biochemical parameters and nutrient imbalances. These Cd-induced alterations resulted in lower plant growth, which might have further implications on plant performance at the population level.

Root morphology ion absorption and antioxidative defense system of two Chinese cabbage cultivars (Brassica rapa L.) reveal the different adaptation mechanisms to salt and alkali stress.

Salt stress and alkali stress are major factors that affect the growth and production of Chinese cabbage. To explore their tolerant mechanism to salt and alkali stress, three salinity levels (0, 50, 100mmol/L NaCl) and three different pH levels (pH6.5, pH7.5, pH8.5) were interactively applied on Qinghua (salt-tolerant-alkali-sensitive) and Biyu (salt-sensitive-alkali-tolerant) cultivars; the root morphology, ion content and antioxidant enzymes were determined. The results showed that the root morphology and root water content of Qinghua under S0pH7.5 and S0pH8.5 were seriously affected, and the content of H2O2 and MDA increased by 143%, 190% and 234%, 294%, respectively, compared with S0pH6.5; when Biyu was under S50pH6.5 and S100pH6.5 stress, the content of H2O2 and MDA increase to 152%, 208% and to 240%, 263%, respectively, but the activities and genes expression of SOD, POD, CAT, AAO, APX, DHAR and MDHAR did not change. The root and the contents of H2O2 and MDA were not affected when Qinghua was treated with salt and Biyu was treated with alkali, but the activities of the antioxidant enzymes increased to 150-200%, and their relative expression was overexpressed and 2.5-3.5-fold of the S0pH6.5. The increase of Na+ in Qinghua was limited under salt stress, Mg2+ in Biyu increased significantly under alkali stress. These all indicated that the adaptability of roots could reflect the degree of tolerance; Chinese cabbage with high salt and alkali tolerance enhanced the regulation of their absorption of ions and increased the relative expression and activities of related antioxidant enzymes.

Increased pH-mediated alleviation of copper-toxicity and growth response function in Citrus sinensis seedlings

Little is known about pH-mediated alleviation of copper (Cu)-toxicity in plants. ‘Xuegan’ [Citrus sinensis (L.) Osbeck] seedlings were irrigated with nutrient solution at a pH 3.0, 4.0 or 4.8 and a concentration of 0.5 (control) and 300 (Cu-toxicity) μM CuCl2 for 17 weeks. Thereafter, a total of 125 physiological parameters including biomass, nutrient elements in roots, stems and leaves, relative water content (RWC) in roots and leaves, and pigments, gas exchange, chlorophyll (Chl) a fluorescence (OJIP) transients and related fluorescence parameters in leaves were investigated in order to understand the physiological mechanisms for increased pH-mediated alleviation of Cu-toxicity. Our results clearly demonstrated that both pH 3.0 (at a concentration of 0.5 or 300 μM Cu) and 300 μM Cu (at a pH of 3.0, 4.0 or 4.8) were toxic to C. sinensis seedlings, as indicated by decreased biomass and/or CO2 assimilation. Raised pH decreased Cu uptake per plant (root dry weight) and Cu concentration in roots, stems and leaves and mitigated Cu-toxic damage to root growth and function, thus improving the uptake of water (root and leaf RWC) and some nutrients (nitrogen, potassium, phosphorus, magnesium, calcium, sulfur and iron), as well as the distribution of some nutrient elements (potassium, sulfur and zinc) in leaves, hence mitigating Cu-toxic impairment on the whole electron transport chain and increasing plant growth, leaf pigment level and CO2 assimilation. Principal component analysis (PCA) indicated that Cu-toxic-effects on all these physiological parameters as a whole decreased with increase of pH. Low pH (pH 3.0) effects on OJIP transients and most of physiological parameters were less pronounced in control than in Cu-toxic seedlings. Interactive effects of pHCu were significant on 84 physiological parameters. To conclude, low pH intensified Cu-toxic effects on C. sinensis seedlings; Cu-toxicity aggravated low-pH effects on C. sinensis seedlings.

Enhancement of drought tolerance in Triticum aestivum L. seedlings using Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11

BackgroundThe effectiveness of two PGPB; Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11 was investigated in enhancing the drought tolerance of wheat (Triticum aestivum L.) seedlings cultivar Gemiza9. The inoculated or uninoculated grains were sown in unsterilized sandy soil and watered normally untill the 8th day. Drought stress was initiated by completely withholding water for 7 days (until wilting). Samples were collected after 15 days from sowing to evaluate some growth criteria, damage and defense indicators and to analyze the roots’ protein pattern.ResultsThe results showed that inoculating wheat seedlings with these strains significantly diminished the inhibitory effects of drought stress on the relative water content of roots, shoots and leaves; area of leaves; contents of pigments (chlorophyll a and b) and ascorbic acid; and on the protein patterns of roots. Moreover, the bacterial inoculation notably reduced the drought-induced damage indicated by lower leakage of electrolytes and less accumulation of Malondialdehyde and hydrogen peroxide, surprisingly with less enhanced production of proline and activities of catalase and peroxidase than their uninoculated counterparts. Under normal conditions, inoculating wheat plants with these PGPB resulted in significantly promoted growth and elevated contents of pigments and altered protein patterns of roots.ConclusionOverall, we can say that both Azospirillum brasilense NO40 and Stenotrophomonas maltophilia B11 were able to deactivate the growth inhibition in wheat seedlings to some extent, while maintaining a certain level of efficient protection against damage under drought stress.

Simulation of palm oil root water uptake by using 2D numerical soil-water flow model.

The lack of water resource in these past decades encourages the implementation of the precision agriculture system towards the sustainability in palm oil plantation. Therefore, it requires a specific information about the palm oil performance regarding the water balance system that affect the water consumption through the plant root water uptake. However, the prediction of root water uptake distribution is still a challenge. Another method to investigate the soil water dynamics under the plant root system is through the numerical simulations that are widely use to assess the soil water flow of the plant. In alignment with the idea of promoting the sustainable palm oil plantation, the investigation of root water uptake and water content under oil palm tree is highly demanding. As an introduction, through this study, it is find of interest to simulate the root water uptake and water content pattern of oil palm tree using the 2D simulation soil-water flow. The study was performed by applying the 2D simulation soil-water flow model to 17th year old oil palm tree located in Siak, Riau with the loam soil type. The climate data was used as primary data to predict the rate of evapotranspiration. The soil properties and root dimension and distribution of oil palm was taken by the literature study. The simulation over 30 days illustrated the root water uptake distribution, water content change, pressure head and flow velocity. The most intensive root water uptake occurred in the upper root zone of oil palm tree as an impact of the higher root density. The significant root water uptake in the upper root zone lead to the decreasing of water content and increasing of pressure head in the soil. Consequently, there was a change of water flow direction from the wet area in the downward and sideward do dry root zone as the water supply to the oil palm tree.

CARACTERÍSTICAS MICROMORFOLÓGICAS DE SUSTRATOS ORGÁNICOS Y SU RELACIÓN CON RETENCIÓN DE AGUA Y CRECIMIENTO RADICAL

El estudio de la micromorfología permite comprender el funcionamiento hídrico y la respuesta fisiológica de los cultivos en un sustrato. En la investigación se evaluó el efecto de la micromorfología de mezclas de materiales orgánicos, sobre el contenido de agua y el crecimiento radical de crisantemo. La hipótesis fue que la descripción de la micromorfología de nuevas propuestas de sustratos permitiría inferir la contención, el movimiento del agua y en consecuencia el crecimiento radical. Materiales orgánicos se utilizaron como: aserrín (AP) y viruta de pino (VP), bagazo de henequén (BH), polvo de coco (PC) y un sustrato testigo (turba:Agrolita®). Siete mezclas se evaluaron plantando esquejes enraizados en contenedores con capacidad de 1250 mL. En las mezclas se determinó potencial hídrico (ψ), volumen radical (VR) y peso seco de raíces (PSR); en las hojas, el contenido relativo de agua (CRA) y el uso eficiente del agua (UEA). La micromorfología y la porosidad se caracterizaron a través de la descripción de secciones delgadas. Los resultados indicaron que la forma y distribución del tamaño de partículas, el grado de descomposición de la materia orgánica y el tipo y tamaño de poro, influyeron en la retención y el movimiento del agua en un sustrato. La mezcla de bagazo de henequén y aserrín en una relación 20:80, formó poros de empaquetamiento compuesto, de tamaños entre 50 y 500 μm y superó a la mezcla testigo en el uso eficiente del agua, sin diferencias significativas en potencial hídrico, contenido relativo de agua, volumen radical, ni peso seco de raíces. La combinación de polvo de coco y aserrín de pino formó poros de empaquetamiento compuesto y microporos &lt;50 μm que dificultaron el movimiento del agua y afectaron el crecimiento de las raíces. En la mezcla 20PC:80VP el 80% de las partículas fueron &gt;200 μm, con poros de empaquetamiento simples con 80% de tamaños de 200 a 500 μm que ocasionaron la percolación del agua y una disminución del (ψ) potencial hídrico.

An Automatic Processing Framework for In Situ Determination of Ecohydrological Root Water Content by Ground-Penetrating Radar

Root water content (RWC) is a vital component in water flux in soil–plant–atmosphere continuum. Knowledge of RWC helps to better understand the root function and the soil–root interaction and improves water cycle modeling. However, due to the lack of appropriate methods, field monitoring of RWC is seriously constrained. In this study, we used ground-penetrating radar (GPR), a common geophysical technique, to characterize RWC of coarse roots noninvasively. An automatic GPR data processing framework was proposed to (1) identify hyperbolic root reflections and locate roots in GPR images and (2) extract waveform parameters from the reflected wave of identified roots. These waveform parameters were then used to establish an empirical model and a semiempirical model to determine RWC. We validated the developed models using GPR root data at three antenna center frequencies (500 MHz, 900 MHz, and 2 GHz) that were produced from simulation experiments (with RWC ranging from 70% to 150%) and field experiments in sandy soils (with RWC ranging from 66% to 144%). Our results show that both the empirical and the semiempirical models achieved a good performance in estimating RWC with similar accuracy, i.e., the prediction error [root-mean-square error (RMSE)] was less than 8% for the simulation data and 12% for the field data. For both models, the accuracy of RWC estimation was the highest when applied to 2-GHz data. This study renders a new opportunity to determine RWC under field conditions that enhances the application of GPR for root study and the understanding and modeling of ecohydrology in the rhizosphere.

Physiological, biochemical, and transcriptional regulation in a leguminous forage Trifolium pratense L. responding to silver ions

Trifolium pratense L. (red clover) is an important leguminous crop with great potential for Ag-contaminated environment remediation. Whereas, the molecular mechanisms of Ag tolerance in red clover are largely unknown. Red clover seedlings were used for physiological and transcriptomic investigation under 0, 20, 50, and 100 mg/L Ag+ stress in our research to reveal potential molecular resistance mechanism. Research showed that red clover possessed fairly strong Ag absorbance capacity, the Ag level reached 0.14 and 2.35 mg/g·FW in the leaves and roots under 100 mg/L AgNO3 stress condition. Root fresh weight, root dry weight, root water content, and photosynthetic pigments contents were significantly decreased with elevating AgNO3 concentration. Obvious withered plant tissue, microstructure disorder, and disrupted organelles were observed. In vitro evaluations (e.g., PI and DCFH-DA staining) represented that AgNO3 at high concentration (100 mg/L) exhibited obvious inhibition on cell viability, which was due possibly to the induction of reactive oxygen species (ROS) accumulation. A total of 44643 differentially expressed genes (DEGs) were identified under Ag stress, covering 27155 upregulated and 17488 downregulated genes. 12 stress-responsive DEGs was authenticated utilizing real-time quantitative PCR (qRT-PCR). Gene ontology (GO) analysis revealed that the DEGs were mostly related to metal ion binding (molecular function), nucleus (cellular component), and defense response (biological process). Involved DEGs in sequence-specific DNA binding transcription factor activity, response to various hormones (e.g., abscisic acid, IAA/Auxin, salicylic acid, and etc), calcium signal transduction, and protein ubiquitination were concluded to play crucial roles in Ag tolerance of red clover. On the other hand, Kyoto Encyclopedia of Genes and Genomes (KEGG) database annotated several stress responsive pathways such as plant-pathogen interaction, phenylpropanoid biosynthesis, ubiquitin mediated proteolysis, hormone signal transduction, and autophagy. Several down-regulated genes (e.g., RSF2, RCD1, DOX1, and etc) were identified indicating possible metabolic disturbance. Besides, protein-protein interaction network (PPI) identified several pivotal genes such as ribosomal proteins, TIR, and ZAT.

Variability in root biomechanics of Chrysopogon zizanioides for soil eco-engineering solutions

AimsWe investigated and compared the variability in biomechanical properties of Chrysopogon zizanioides L. (vetiver grass), including tensile strength, Young's modulus, and breakage strain, which have direct implication to root reinforcement to slope. MethodsWe tested the effects of growth condition (pots versus field), root water content (hydrated versus oven dried), and loading speed (16 mm/min versus 200 mm/min) on the biomechanical properties of vetiver roots (n = 344) via a series of uniaxial tensile tests. We also measured the root biomechanical traits such as diameter, density, degree of saturation, and relative root dry weight. ResultsAlthough the strength and modulus followed a negative power law relationship with root diameter (R2 up to 0.69), the strain–diameter relationship was linear (R2 = 0.20). Growth condition and loading speed did not have significant effects on the root biomechanical properties, whereas root water content showed significant effects on these properties, particularly in fine roots (<0.9 mm). Dried roots had higher strength and modulus but smaller strain than hydrated roots. ConclusionA major source of the variability in strength, modulus, and strain of vetiver roots was root water content, which occurred primarily in fine roots (<0.9 mm). Considering slope stability, testing hydrated roots would give a lower estimate of strength than the case of dried roots, but it might overestimate root ductility and underestimate the time-of-slope failure.

Use of seed priming to improve Cd accumulation and tolerance in Silene sendtneri, novel Cd hyper-accumulator

Changes in the environment as a result of industrialisation and urbanisation impact negatively on plant growth and crop production. Cadmium (Cd) is one of the most dangerous metals that enters the food chain, with toxic effects on plants and human health. This study evaluated the potential of Silene sendtneri as a novel hyperaccumulator and the role of seed priming in tolerance and accumulation rate of Cd. The effect of different priming agents on germination performance, root growth, seedling development, metal uptake and accumulation, antioxidant defences including enzymatic and non-enzymatic antioxidants has been assessed. Seed priming using silicic acid, proline alone or in combination with salicylic acid- enhanced germination, seedling development, and root growth under Cd stress. The same priming treatments induced an increase of water content in shoots and roots when plants were exposed to Cd. The enzymatic antioxidant response was specific for the priming agent used. An increase in ferulic acid and rutin in shoots was related to the increase of Cd concentration in the medium. The concentration of malic and oxalic acid increased significantly in shoots of plants grown on high Cd concentrations compared to low Cd concentrations. Silene sendtneri can accumulate significant levels of Cd with enhanced accumulation rate and tolerance when seeds are primed. The best results are obtained by seed priming using 1% silicic acid, proline and salicylic acid.

Genotypic evaluation of cowpea germplasm for salinity tolerance at germination and during seedling growth

Abstract Soil salinity represents a major constraint limiting crop production in arid and semi-arid countries. The effect of salinity induced by sodium chloride (NaCl) at five levels (0, 50, 100, 150 and 200 mM) was investigated on four germination traits and thirteen seedling growth characteristics in twenty cowpea [Vigna unguiculata (L.) Walp.] genotypes (ET11, KEB-CP004, KEB-CP006, KEB-CP009, KEB-CP 010, KEB-CP020, KEB-CP033, KEB-CP038, KEB-CP039, KEB-CP045, KEB-CP051, KEB-CP054, KEB-CP057, KEB-CP060, KEB-CP067, KEB-CP068, KEB-CP118, MTA22, NO74 and NO1036). The germination tests were carried out on Petri dishes in the laboratory while seedling growth experiments continued in plastic pots in the greenhouse, both setting up using a randomised complete block design with three replications. Genotypic responses were significant for all germination traits (p &lt; 0.001). Germination percentage, germination rate index, and coefficient of velocity of germination were all decreased by salt stress. However, the mean germination time increased with increasing saline conditions. Significant differences were found between genotypes for most growth attributes. Growth rate (centimeter increased in height per week) decreased significantly with increasing salinity, starting at 100 mM NaCl (24.20% reduction, 2.66 cm / week) with maximum reduction (38.58%) corresponding to 2.16 cm/week observed at 200 mM NaCl, compared to control (3.51 cm/week growth rate). Also, significant decline in shoot weights, number of functional leaves and dry matter production were observed under salinity. Salinity also reduced water content in shoot and root and did not affect root weights. Under salinity, significant correlations were found between all germination variables (p &lt; 0.001). Growth rate was significantly associated with ten out of the twelve other seedling growth traits. Also, the dry matter production under salinity was significantly associated with all other seedling growth characteristics with the exception of root water content. Given the effect of salt stress, cowpea genotypes, namely NO1036, KEB-CP004, KEB-CP038 and KEB-CP051, were the most tolerant while KEB-CP068 and ET11 were the most sensitive ones. The results confirm substantial genetic variation in salt stress tolerance among the studied genotypes. The most tolerant genotypes should be further explored in genetic improvement programs and should be promoted for culture in regions affected by salinity.

Study on the influence of soil moisture and plant roots on slope stability of dump

Under the background of ecological civilization construction and comprehensive promotion of "green mine" construction in China, for the waste dump formed by a large amount of abandoned soil and slag in the process of mineral resource production, it is one of the important contents of mine ecological restoration to restore and reconstruct the ecology, especially the slope vegetation. Based on the origin of the dump, when rainfall or irrigation water infiltrates into the soil, the physical and mechanical properties of slope soil are changed, and the shear strength of soil is continuously reduced, which has a negative impact on the slope stability. In this paper, we take south mining of DaTang open-pit mine as an example, through field investigation and sampling, laboratory analysis and the computer software analysis method, we set up soil shear strength parameters under different soil water content and different depth of plant roots, using the Slope stability of Slope/W module, establishing the model of slope . Based on limit equilibrium theory to calculate the safety factor, it is concluded that under the condition of the bare Slope stability of Slope soil water safety threshold is 14%. The root system of slope vegetation plays an important role in slope stability, in which the effect of leguminous vegetation on slope stability is obviously better than that of gramineous vegetation. When the soil moisture of slope is 20%, the slope stability coefficient can be increased by 7%.

Relationship between Very Fine Root Distribution and Soil Water Content in Pre- and Post-Harvest Areas of Two Coniferous Tree Species

Tree root system development alters forest soil properties, and differences in root diameter frequency and root length per soil volume reflect differences in root system function. In this study, the relationship between vertical distribution of very fine root and soil water content was investigated in intact tree and cut tree areas. The vertical distribution of root density with different diameter classes (very fine &lt;0.5 mm and fine 0.5–2.0 mm) and soil water content were examined along a slope with two coniferous tree species, Cryptomeria japonica (L.f.) D. Don and Chamaecyparis obtusa (Siebold et Zucc.) Endl. The root biomass and length density of very fine roots at soil depth of 0–5 cm were higher in the Ch. obtusa intact tree plot than in the Cr. japonica intact plot. Tree cutting caused a reduction in the biomass and length of very fine roots at 0–5 cm soil depth, and an increment in soil water content at 5–30 cm soil depth of the Ch. obtusa cut tree plot one year after cutting. However, very fine root density of the Cr. japonica intact tree plot was quite low and the soil water content in post-harvest areas did not change. The increase in soil water content at 5–30 cm soil depth of the Ch. obtusa cut tree plot could be caused by the decrease in very fine roots at 0–5 cm soil depth. These results suggest that the distribution of soil water content was changed after tree cutting of Ch. obtusa by the channels generated by the decay of very fine roots. It was also shown that differences in root system characteristics among different tree species affect soil water properties after cutting.

Short-term drought exposure decelerated growth and photosynthetic activities in chili pepper (Capsicum annuum L.)

Chili pepper (Capsicum annuum L.) is a preferred vegetable by local farmers at a riparian wetland in Indonesia due to high market demand and its economic value. Chili pepper can be grown immediately after rice harvesting, concurrently with the early dry season. Three chili pepper varieties, namely Genie, Romario, and Laris were evaluated for their adaptability to drought condition. Drought treatment was imposed for 7 days until soil water potential was dropped to around −30 to −40 kPa. Morphological and photosynthetic traits were measured at pre-, during, and post-drought exposures. Growth analysis was calculated based on measured morphological traits. Results indicated that the number of leaves (NoL), total leaf area (TLA), total accumulated dry matter (TDM), and relative growth rate (RGR) were negatively affected by drought. Water content of shoot (SWC), leaf (LWC), and root (RWC) were significantly decreased during drought exposure; yet, able to fully recover at 7 days after drought treatment was terminated. Decrease in shoot root ratio (SRR) and leaf weight ratio (LWR); reversely, increase the root weight ratio (RWR) under drought condition, was not associated with enhancement of root growth. Rather, it was due to less negatively effect of drought on roots than on the above-ground organs. Simultaneously, chlorophyll fluorescence, LWC, stomatal conductance, transpiration and photosynthetic rates declined during drought exposure. However, 7 days after drought treatment was terminated, all traits were able to return to pre-drought levels. Among chili pepper varieties studied, Genie exhibited better overall performance than Laris and Romario did under drought stress condition.