Conductivity Of Soil Saturation Extract Research Articles

Foliarly Applied 24-Epibrassinolide Modulates the Electrical Conductivity of the Saturated Rhizospheric Soil Extracts of Soybean under Salinity Stress.

The accumulation of salts within the rhizosphere is a common phenomenon in arid and semi-arid regions where irrigation water is high in salts. A previous study established the ameliorative effect of foliarly applied 24-epibrassinolide (BR) on soybean under salinity stress. As a follow-up to that study, this work evaluated the effects of BR on the electrical conductivity of saturated soil extracts (ECses) under soybean exposed to salt stress. Three salinity levels (3.24, 6.06 and 8.63 dS/m) in a factorial combination with six frequencies of BR application—control, seedling, flowering, podding, seedling + flowering and seedling + flowering + podding—were the treatments, and the rhizospheric ECse was monitored from 3 to 10 weeks after the commencement of irrigation with saline water (WAST). The principal component analysis revealed that samples in saline BR treatments clustered together based on the BR application frequencies. There was a significant increase in ECse with increases in salinity and WAST. The frequent application of BR significantly reduced ECse to 5.07 and 4.83 dS/m relative to the control with 6.91 dS/m, respectively, at week 10. At 8.63 dS/m, the application of BR (seedling + flowering + podding) reduced ECse by 31.96% compared with the control. The underlining mechanism is a subject for further investigation.

Peanut shell biochar’s effect on soil physicochemical properties and salt concentration in highly saline-sodic paddy fields in northeast China

Soil salinization is a major ecological threat to crop growth and production. Biochar addition can alleviate the negative impacts of saline-sodic stress in crops. Here, a two-year field experiment was conducted in a highly saline-sodic paddy field to evaluate the response of soil physico-chemical properties, ionic concentration, and rice yield to biochar applications. The soil was amended with peanut shell biochar as follows: zero biochar (B0), 33.75 t ha−1 (B1), 67.5 t ha−1 (B2), and 101.25 t ha−1 (B3). Biochar significantly reduced soil bulk density (BD), while it markedly increased total porosity (TP) and saturated hydraulic conductivity (Ks). Furthermore, biochar markedly decreased the Na+ concentration, Na+/K+ ratio, Na+/Ca2+ ratio, HCO3-, and CO32- while it increased the concentrations of K+, Ca2+, and Mg2+. Biochar significantly decreased the electrical conductivity of soil saturation extract (ECe). The exchangeable sodium percentage (ESP) of B1, B2, and B3 were 53.6%, 62.3%, and 71.0% lower, respectively, than that of B0, and the corresponding decrease in sodium adsorption ratio (SARe) was 51.2%, 58.1%, and 60.5%. Biochar had no effect on the soil pH but significantly increased the soil cation exchange capacity (CEC). The rice biomass yield, grain yield, and harvest index significantly increased after biochar application.

Rice Production in Farmer Fields in Soil Salinity Classified Areas in Khon Kaen, Northeast Thailand

Northeast Thailand is the largest rice cultivation region in Thailand, but the rice yield there is quite low. Soil salinity is one of the major yield restricted factors, is derived from underground rock salt, and is predicted to expand in the future. This study focused on evaluating rice productivity related to salinity conditions in Khon Kaen Province, Northeast Thailand. The field investigations were conducted from 2017 to 2019 in farmer fields in severe, moderate, and slight soil salinity classes determined by the Land Development Department of Thailand. The soil salinity on the basis of the electric conductivity of saturated soil extract (ECe) varied year to year, which seemed to be associated with precipitation. The difference in soil salinity between classes was obvious only in the drought year 2018, and reflected in the rice yield, although severe drought devastated rice yield in some fields. Plenty of rainfall may have alleviated soil salinity and rice yield reduction in other years, causing differences in rice yield that were not significant among soil salinity classes. However, salinity level evaluation by the USDA based on ECe showed that rice yield was damaged depending on the level. This study indicates that ECe-based evaluation is recommended for soil salinity in relation to rice productivity. The spatial and temporal evaluation for rice production may benefit farmers. The results in this study also showed rice production largely varied even in similar salinity levels, implying that salinity damage can be alleviated by farmer management.

Photosynthesis and salt cations adsorption response of spring maize ( Zea mays L.) to salinity stress caused by different drip irrigation regimes in an arid saline area, Northwest China

Photosynthesis and salt cations adsorption response of spring maize ( <i>Zea mays</i> L.) to salinity stress caused by different drip irrigation regimes in an arid saline area, Northwest China

Salinification and salt transports under aeolian processes in potential desertification regions of China

China has aeolian and salinization desertification, however, the role of salt transports by wind on salinization processes in potential desertification regions (PDR) is poorly understood. In this study, electrical conductivity of soil saturated extract (ECe), pH values of 1163 surface soil and aeolian transport samples acquired from nine PDRs and the effect of salt transports under aeolian processes on salinification was determined based on wind tunnel experiments. The results show that the maximum ECe values of the surface soils in PDRs such as Hulun Buir, Nunkiang, Horqin, Otindag, Ordos, Qinghai, and Junggar were less than 3 dS/m, and there was low salinization risk and the dominant desertification in these regions was aeolian desertification. Likewise, the ECe values of surface soils in the other regions such as the Ala Shan & Hexi Corridor and Tarim were 2.67 ± 1.98 and 10.3 ± 13.13 dS/m, respectively, which show nonsaline and saline soils existence and there is a risk of both aeolian desertification and salinization in PDRs. Annual precipitation is the key factor in salinization controlling in China's PDRs and soil accumulation easier occurred in regions with annual precipitation less than 70 mm due to inadequate leaching. In addition, the wind tunnel experiment results show that under aeolian processes the variability of ECe values of aeolian transports ranged between 2.56% and −15.68%, and the aeolian processes could lower the ECe values of surface soils in most regions. The variability of ECe of the aeolian transports under low free wind speed (14 m/s) and high free wind speed (22 m/s) ranged between −7.87% and 8.77%. Our results highlight that besides the variations in groundwater level, the aeolian processes may play a more important role in salt transports and have exerted potential effects on salinization processes in the region, which may improve decisions in a desertification combating.

Effect of Irrigation Water Salinity and Deficit Irrigation on Soil Ions Variation and Uptake by Saffron (Crocus sativus L.) Under Two Planting Methods

A 2-years field experiment in a split-split plot arrangement was considered to investigate the effects of different irrigation water salinity [0.45 (well water, S1), 1.0 (S2), 2.0 (S3), 3.0 (S4) dS m−1], irrigation water levels [100% (I1), 75% (I2) and 50% (I3) of saffron water requirement (WR)] and planting methods [basin (P1) and in-furrow (P2)] on the dynamics of salt ions and their uptake by saffron plant (Crocus sativus L.). The electrical conductivity of soil saturation extract (ECe) was increased by 104% in S4 compared to control (S1), on average, in two growing seasons. S4 treatment increased concentration of sodium (Na+), calcium (Ca2+), potassium (K+) and chloride (Cl−) in soil by 102%, 92%, 124% and 128% in comparison with S1, on average, in two growing seasons. The concentration of Na+, Ca2+, K+ and Cl− in soil in S4 were 30%, 15%, 28% and 29% higher and NO3 was 30.3% lower in I1 in comparison with I3, respectively. The ions concentration in soil were 3.5–14.7% higher in P1 in comparison with those in P2. Leaf Na+, Ca2+ and Cl− concentration was increased by increase in irrigation water salinity while K+, nitrogen (N) and phosphorus (P) concentrations were decreased by 28.4%, 25.7% and 29.8% in S4 in comparison with that obtained in S1, on average, which is presumably due to reduced NO3 and P concentrations in soil and increased Na+ uptake by saffron. Also, deficit irrigation reduced soil and leaf ions (Na+ and Cl−) threshold and increased the slope of relative yield-ions concentration reduction function, which indicated that water stress aggravates saffron sensitivity to salinity and ions concentration in soil and leaf. Results indicated that saffron was more sensitive to Na+ concentration in soil extract compared with Cl−. Na+ and Cl− threshold was 19.3% and 27.1% higher in P2, on average, in different irrigation levels, respectively. Therefore, the in-furrow planting method is suggested to cope with unfavorable saffron field conditions.

Role of rhizospheric microorganisms in mitigating the adverse effect of salinity stress in Plantago ovata growth, biochemical and photosynthetic traits

ABSTRACT This pot experiment was carried out to investigate the efficiency of plant rhizospheric microorganisms (PRMs) to counteract salinity stress in Plantago ovata. The treatments included soil salinity (2.5 (as control), 5 and 10 dS m−1), arbuscular mycorrhizal fungi (Control, Glomus mosseae, Rhizophagus intraradices and Funneliformis mosseae) and phosphate solubilizing bacteria (Control and Pseudomonas fluorescens). The highest amount of growth and yield parameters, relative water content (RWC), potassium (K+) and phosphorus (P) concentration, photosynthetic traits (chlorophyll a and b, carotenoid, maximal efficiency of PSII (fv/fm), variable fluorescence to initial fluorescence (fv/f0) and stomatal conductance (gs)), antioxidant enzymes and the lowest sodium (Na+) concentration, malondialdehyde (MDA) and electrolyte leakage were observed in the plants treated with mixture of Rhizophagus intraradices and Pseudomonas fluorescens under all salinity levels. Although all previously mentioned traits significantly and severely decreased under salinity stress, mucilage percentage, electrolyte leakage and Na+ concentration were increased under salinity levels. In conclusion, the results suggested that inoculation of AMF (particularly Rhizophagus intraradices) in combination with Pseudomonas fluorescens by the accumulation of proline along with decreased electrolyte leakage, maintenance of relative water content in leaves and selective uptake of K+ ions could overcome detrimental effects of salinity stress in isabgol. Abbreviations AMF: arbuscular mycorrhizal fungi; APX: ascorbate peroxidase; CAT: catalase; Chl: chlorophyll; CAR: carotenoids; ECe: electrical conductivity of soil saturation extract; EL: Electrolyte leakage; Fv/Fm: maximal efficiency of PSII; gs: stomatal conductance; Fv/F0: variable fluorescence to initial fluorescence; K+: potassium; MDA: malondialdehyde; Na+: Sodium; PGPR: plant growth-promoting rhizobacteria; P: phosphorus; PRM: plant rhizospheric microorganisms; PSB: phosphate solubilizing bacteria; RWC: relative water content; SOD: superoxide dismutase

The Dynamic Yield Response Factor of Alfalfa Improves the Accuracy of Dual Crop Coefficient Approach under Water and Salt Stress

The accurate quantification of crop water use or evapotranspiration (ET) under water and salt stress is needed for efficient water management and precision irrigation in water scarce regions. However, few studies were examined on alfalfa water use and its components under water and salt stress. We carried out two field experiments to quantify alfalfa water use through setting up different water and salt gradients, including two irrigation levels (full and deficit irrigation) and four soil salinity levels (0, 2‰, 4‰ and 6‰ salt of mass ratio) in an arid region of Northwest China. Electrical conductivity of soil saturation extract (ECe), soil water content (SWC), leaf area index (LAI) and soil evaporation (E) were measured. The SIMDualKc model, which uses the FAO56 dual Kc approach, was calibrated and validated using measured SWC and E. Model results show a good agreement between observed and simulated SWC and E without stress. The depletion fraction for no stress (p) and the percent yield reduction per unit increase in soil salinity (b) were 0.50 and 6.0%/(dS m−1), respectively, slightly lower than those of FAO-56 (0.55 and 7.3%/(dS m−1)). The difference indicates that alfalfa has a lower capacity of water use but a greater tolerance to salt stress after soil salinity reached its sensitivity threshold in the arid region. The model performed a reduced accuracy under water and salt stress and the differences tended to increase as stress increased, which was partly attributed to constant yield response factor (Ky) under different soil water and salt stress. The key parameter Ky dynamically increased with the increased degree of stress. Compared to constant Ky, the simulations of SWC and E showed improved accuracy with dynamic Ky. These results suggested that the response and acclimation of alfalfa to stress might be incorporated into the dual Kc model through the diversity of Ky.

Ion Concentration Changes in Plants of Varying Tolerance under Saline Environment

Core Ideas Two widely cultivated plant species with different salinity tolerance were grown on coastal saline soils.Five levels of water salinity were set for reclamation of saline land using drip irrigation.Ion homeostasis in two plants organs differed with plant salinity tolerance.The threshold of water salinity for two plants was determined. Two widely cultivated plant species (Buddleja alternifolia Maxim. and Weigela florida ‘Red Prince’) with different salinity tolerances were grown in coastal saline soils around Bohai Gulf, China, using drip irrigation at five levels of salinity: 0.8, 3.1, 4.7, 6.3, and 7.8 dS/m. The soil salinity (electrical conductivity of soil saturated extract, ECe), soil pH, plant survival rate, and ion concentration changes in plants were investigated. The results showed that a low soil salinity environment with ECe &lt; 4 dS/m for all saline water treatments was quickly created and maintained especially in the root zone, which confirmed the effectiveness of drip irrigation in salt leaching. Liquid acid added with drip irrigation is proposed in the early reclamation period to avoid alkalization. Ion homeostasis differed with plant salinity tolerance, increasing of K+, Ca2+/Na+, and K+/Na+ in plant tissues and decline of Na+ in the leaf for B. alternifolia were correlated with higher survival rates compared with that of W. florida (Red Prince). Fertilization with K+ and Ca2+ was proposed to reduce the deleterious effects of salinity, especially for salt‐sensitive plants. Irrigation water of salinity up to 7.8 and 3.1 dS/m could be applied in the field to B. alternifolia and cultivar Red Prince, respectively, while maintaining a &gt;75% survival rate.

Spatial distribution of soil moisture, soil salinity, and root density beneath a cotton field under mulched drip irrigation with brackish and fresh water

Root systems play a vital role in soil-plant interactions. The dynamics and distributions of soil moisture content (SMC), soil salinity, and cotton (Gossypium hirsutum L.) root density under mulched drip irrigation are complex and their interactions are not well understood. The aim of this study is to describe these dynamics and distributions and to evaluate their impacts on cotton above-ground growth and yield during two-year field experiments in a cotton field under mulched drip irrigation with brackish and fresh water. Significant differences were observed for the distributions of SMC, soil salinity, and root length density (RLD) in the root zone for brackish water irrigation treatment (BWT) and fresh water irrigation treatment (FWT). The average SMC and soil salinity in the root zone were higher for BWT than for FWT. The spacing of irrigation lines also had measurable impacts. SMC was less variable when irrigation spacing was small (narrow rows) than beneath wide rows. SMC for BWT and FWT decreased after irrigation due to root water uptake; simultaneously, salt concentration increased, especially in regions where RLD was relatively high. More roots were observed growing in the mulched narrow and wide rows than in the no-mulch zone. Roots were concentrated in the shallowest 30cm. Our study indicated that the average values of the ECe (electrical conductivity of soil saturation extract) in the root zone after BWT irrigation were higher than the published threshold value for optimal cotton yield. The average RLD, shoot dry weight and yield for BWT were observed to be lower than those of FWT as a result of the elevated soil salinity associated with BWT.

Simulations of both soil water content and salinity under tape drip irrigation with different salinity levels of water

The purpose of the present research is to evaluate HYDRUS-2D model so as to simulate soil water content and salinity under field conditions. Soil texture is a heterogeneous heavy soil. In this research, drip irrigation (tape) system was applied as a line source with water salinities of 1.279, 2.5, and 5 dS m−1 in three volumes of irrigation water including 10, 15, and 20 l. The observed soil moisture and Electrical conductivity of soil saturated extract (ECe) values were compared with the simulated values using normalized Root Mean Square Error (nRMSE) and Coefficient of Residual Mass (CRM). Ranges of water content nRMSE were between .91 and 2.07%, and those of CRM were between −.0080 and .0170. For salinity, ranges of CRM for beneath the tape were between −.049 and .097 and between −.065 and .081 for the horizontal distance. Ranges of nRMSE for beneath the tape and the horizontal distance were between 2.79 and 18.49% as well as 3.08 and 20%, respectively. The performance of the model was placed in excellent category to simulate the soil water content; in addition, it was placed in good to excellent classes to simulate soil salinity.

Chemical attributes of soil and dry mass accumulation of maize fertilized with cassava wastewater

The aim of this study was to evaluate chemical attributes alterations of a clay-loam textured soil and dry mass accumulation of maize submitted to application of cassava wastewater doses in three assessment periods. The experiment was conducted under greenhouse using a completely randomized experimental design in a factorial 5 × 3, with four replicates. The analyzed factors of research were doses of cassava wastewater (0; 12.6; 25.2; 50.4; 75.6 m3 ha-1) andassessment periods (20, 40 and 52 days after germination). The following parameters were determined: electric conductivity of soil saturation extract, pH in water, content of available P, content of exchangeable K+, Ca2+, Mg2+ and Na+ of soil, dry mass of leaves and stem. The application of cassava wastewater on soil enables increase of pH, electric conductivity of saturation extract, contents of available P, contents of exchangeable K+ and Na+ and dry mass of leaves and stem. However, only pH and content of exchangeable K+ of soil, the electric conductivity of saturation extract and dry mass of leaves and stem are influenced by assessment period.

Reclamation of very heavy coastal saline soil using drip-irrigation with saline water on salt-sensitive plants

High salt content in soil, poor soil structure and fresh water shortage are the restricting factors for construction of ecological landscapes in coastal regions with very heavy saline silt-soil. The aim of this work was to develop a method to reclamate the very heavy coastal saline soil using drip-irrigation with saline water for salt-sensitive plants. A field experiment with five treatments of salinity levels of 0.8, 3.1, 4.7, 6.3 and 7.8dS/m of irrigation water was imposed in the very heavy saline silt-soil in 2012–2014. The initial soil in experimental plots was tilled and broken, and a gravel–sand layer was created at 120cm depth. Chinese rose (Rosa chinensis) is very sensitive to salt and was chosen as the representative plant. Soil indexes (electrical conductivity of soil saturated extract (ECe), pH and sodium adsorption ratio (SAR)), growth characters and dry matter production of rose were determined. The results showed that the level of salinity in water had no significant effect on salt leaching in the 0–120cm soil profile, and significant effects only occurred in shallow soil layers. ECe and SAR of soil profile decreased with irrigation time, but pH of soil initially increased and then decreased. Rose growth and dry weight decreased with increasing of irrigation water salinity. The values of soil salt tolerance threshold were 2.24dS/m at emergence and 4.48dS/m in the growth period after emergence. The emergence rate decreased by 53.30% for each unit of ECe increase in the root zone, and dry weight decreased to zero when ECe exceeded 5.36dS/m. A regulatory method was scheduled for drip-irrigation of saline water to control the soil matric potential (SMP) under a gravel–sand layer for initially saline soils and was effective in reclamation of very heavy coastal saline soil (silt soil) for sensitive species such as Chinese rose. An SMP higher above −5kPa at 20cm depth under the emitter in the first year and −10kPa in the second year, and 6mm of irrigation water of salinity up to 4.01dS/m can be used for rose drip-irrigation scheduling, while also maintaining a 50% survival rate.

Changes of arbuscular mycorrhizal traits and community structure with respect to soil salinity in a coastal reclamation land

A comprehensive knowledge on the relationship between soil salinity and arbuscular mycorrhizal fungi (AMF) is vital for a deeper understanding of ecosystem functioning under salt stress conditions. The objective of this study was to determine the effects of soil salinity on AMF root colonization, spore count, glomalin related soil protein (GRSP) and community structure in Saemangeum reclaimed land, South Korea. Soil samples were collected and grouped into five distinct salt classes based on the electrical conductivity of soil saturation extracts (ECse). Mycorrhizal root colonization, spore count and GRSP were measured under different salinity levels. AMF community structure was studied through three complementary methods; spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Results revealed that root colonization (P < 0.01), spore count (P < 0.01) and GRSP (P < 0.01) were affected negatively by soil salinity. Spore morphology and T-RFLP data showed predominance of AMF genus Glomus in Saemangeum reclaimed land. T-RFLP and DGGE analysis revealed significant changes in diversity indices between non (ECse < 2 dS/m) and extremely (ECse > 16 dS/m) saline soil and confirmed dominance of Glomus caledonium only in soils with ECse < 8 dS/m. However, ribotypes of Glomus mosseae and Glomus proliferum were ubiquitous in all salt classes. Combining spore morphology, T-RFLP and DGGE analysis, we could show a pronounced effect in AMF community across salt classes. The result of this study improve our understanding on AMF activity and dominant species present in different salt classes and will substantially expand our knowledge on AMF diversity in reclaimed lands.

Comportamento hídrico e crescimento do feijão vigna cultivado em solos salinizados

A salinização dos solos reduz a capacidade das plantas de absorver água o que, em geral, provoca diminuição na sua taxa de crescimento. As respostas das plantas ao estresse salino são melhor correlacionadas com o potencial osmótico do que com a condutividade elétrica do extrato de saturação do solo. Com o objetivo de avaliar os efeitos do estresse salino no crescimento, evapotranspiração e potencial osmótico foliar do feijoeiro vigna [Vigna unguiculata L. (Walp.)] conduziu-se um experimento em casa de vegetação da Universidade Federal Rural de Pernambuco (Recife, PE, Brasil). Os tratamentos constaram de um arranjo fatorial 2 x 4 composto de duas texturas de solo e quatro níveis de salinidade do solo (4, 8 e 12 dS m-1 a 25 ºC além da testemunha sem a adição de sais) com cinco repetições. Concluiu-se que a salinidade do solo causa redução no consumo de água, no potencial osmótico foliar, na altura das plantas, no número de folhas e na biomassa seca da parte aérea do feijoeiro vigna.

Electromagnetic induction prediction of soil salinity and groundwater properties in a Tunisian Saharan oasis

Electromagnetic induction measurements (EM) were taken in a saline gypsiferous soil of the Saharan-climate Fatnassa oasis (Tunisia) to predict the electrical conductivity of saturated soil extract (ECe) and shallow groundwater properties (depth, Dgw, and electrical conductivity, ECgw) using various models. The soil profile was sampled at 0.2 m depth intervals to 1.2 m for physical and chemical analysis. The best input to predict the log-transformed soil salinity (lnECe) in surface (0–0.2 m) soil was the EMh/EMv ratio. For the 0–0.6 m soil depth interval, the performance of multiple linear regression (MLR) models to predict lnECe was weaker using data collected over various seasons and years (R a 2 = 0.66 and MSE = 0.083 dS m-1) as compared to those collected during the same period (R a 2 = 0.97, MSE = 0.007 dS m-1). For similar seasonal conditions, for the Dgw–EMv relationship, R 2 was 0.88 and the MSE was 0.02 m for Dgw prediction. For a validation subset, the R 2 was 0.85 and the MSE was 0.03 m. Soil salinity was predicted more accurately when groundwater properties were used instead of soil moisture with EM variables as input in the MLR. Editor D. Koutsoyiannis; Associate editor K. Heal Citation Bouksila, F., Persson, M., Bahri, A., and Berndtsson, R., 2012. Electromagnetic induction predictions of soil salinity and groundwater properties in a Tunisian Saharan oasis. Hydrological Sciences Journal, 57 (7), 1473–1486.

EFFECT OF SALINITY ON SEEDLING EMERGENCE OF LEUCOSPERMUM CUNEIFORME (PROTEACEAE)

Leucospermum cuneiforme, a South African protea species cultivated for cut flowers, was tested in order to determine its salinity tolerance at seedling emergence. The seeds were sown in a mixture of peat-moss and volcanic ash (1:1, v/v). Five water salinity levels (0.5, 1.7, 2.7, 4.8 and 8.2 dS/m) were imposed by irrigating with water that contained NaCl and CaCl 2 (normal ratio 2:1). In Tenerife, water from wells in coastal areas has a similar or higher Na/Ca ratio. Seedling emergence percentages and rates were measured. The increased salinity caused a decrease in the percentage of seedling emergence and a slowing of the process. In regard to seedling emergence rates, L. cuneiforme had a salinity threshold of 2.8 dSm -1 , with a decrease of 28.4% per dS m -1 in the ratio of seedling emergence. In regard to seedling emergence percentages, L. cuneiforme showed a salinity threshold of 3.0 dS/m, with a decrease in the percentage of seedling emergence of 30.8% per dS/m. Threshold expressed as electrical conductivity of saturated soil extract was calculated, showing that, at seedling emergence, L. cuneiforme is moderately tolerant to salinity.

Physiologic responses of precocious dwarf cashew at different levels of salinity

Salinity is an abiotic stress that alters the plant development, limiting plant production. At the present experiment, it was evaluated the effect of salt stress on osmotic potential, content of organic and inorganic solutes, gas exchanges (photosynthesis, transpiration and stomatal conductance) and production of precocious dwarf cashew ( Anacardium occidentale L.). For this, the experiment was carried out at Embrapa Agroindústria Tropical experimental station, in Pacajús, Ceará, Brazil, during the months of August to December. The plants were subjected to increasing levels of salinity using irrigation water with electrical conductivity (EC w ) of 0.5 (control), 4.0, 8.0 and 12.0 dS m -1 . The data were collected monthly and subjected to statistic analyses. Although the electrical conductivity of soil saturation extract (EC se ) increased with salinity, there were no significant differences between treatments for osmotic potential, gas exchange and levels of organic and inorganic solutes. With the exception of leaf osmotic potential and gas exchange, all the others parameters studied varied along the experiment in function of the phenophisiological stage of the plant, presenting greater values in the fructification period. So, the salinity stress was not enough to cause significant changes in growth and productivity of the plants.

Effect of Salinity on Seedling Emergence of Seven Banksia Species Cultivated for Cut Flower and Foliage

ABSTRACT Seven Banksia species were tested in order to determine their salinity tolerance at seedling emergence. Five water salinity levels (0.5, 1.7, 2.7, 4.8, and 8.2 dS m−1 for B. burdettii, B. hookeriana, B. menziesii, and B. victoriae; and 0.2, 1.3, 2.4, 4.7, and 8.5 dS m−1 for B. coccinea, B. occidentalis, and B. speciosa) were imposed by irrigating with water that contained sodium chloride (NaCl) and calcium chloride (CaCl2) (normal ratio 2:1). With regards to seedling emergence rates, the species that showed greater salinity tolerance were B. menziesii and B. occidentalis. With regards to the seedling emergence percentages, B. speciosa was the most salinity-tolerant. The calculation of the thresholds expressed as electrical conductivity of saturated soil extract gave that, at seedling emergence, B. speciosa and B. occidentalis are moderately tolerant to salinity, B. menziesii, B. coccinea, and B. hookeriana are moderately sensitive to salinity, and B. burdettii and B. victoriae are sensitive to salinity.

Interactive Effect of Soil Salinity and Water Stress on Growth and Chemical Compositions of Pistachio Nut Tree

ABSTRACT The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg− 1 soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks (‘Sarakhs’ and ‘Qazvini’) were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (ECe) confirmed the above findings. Under 3-d irrigation interval, the ECe required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na+), potassium (K+), and chloride (Cl−) in pistachio. The concentration of Na+, K+ and C1− ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na+, K+, and C1− in the plant tissues, at lowest irrigation intervals ‘Sarakhs’ shows a higher sensitivity to soil salinity than ‘Qazvini’, but with increasing irrigation interval, ‘Sarakhs’ and ‘Qazvini’ can be classified as resistant and sensitive to salinity, respectively.