Effects Of Soil Salinity Research Articles

Trade-off between leaf chlorophyll and betacyanins in Suaeda salsa in the Liaohe estuary wetland in northeast China

Pigment composition is an important functional trait that can be affected by environmental factors. The objective of this study was to investigate the effect of soil salinity on pigment composition in Suaeda salsa by comparing chlorophyll and betacyanin content in the Liaohe estuary wetland, a typical coastal wetland in northeast China. We investigated the plant biomass, percentage of red leaves and pigment content (chlorophyll a, chlorophyll b and betacyanins) in S. salsa in intertidal and supratidal zones of the upper, middle and lower reaches of the Liaohe estuary wetlands. The Na⁺ content of both the soil and plant was also measured. Full analysis of variance and multivariate analysis were used to compare differences in pigment content and Na⁺ content between the supratidal and intertidal zones. Pigment composition was significantly affected by soil salinity. With increasing soil salinity, the percentage of red leaves was higher in the intertidal zone than in the supratidal zone. In all three reaches, plants had lower chlorophyll a content and higher betacyanin content in the intertidal zone than in the supratidal zone. Compared to chlorophyll a, chlorophyll b was less sensitive to soil salinity. There were no differences in chlorophyll b content between the intertidal and supratidal zones in the upper and lower reaches. Furthermore, pigment composition was associated with both the plant tissue and soil Na⁺ content. Compared to the supratidal zone, the intertidal zone had a higher Na⁺ content in plants. There was a negative relationship between plant chlorophyll content and soil Na⁺ content, but a positive relationship between betacyanin content and soil Na⁺ content. Overall, the results indicated that there might be a trade-off between leaf chlorophyll and betacyanin content in S. salsa to maintain its growth and survival in high salinity environments.

Effect of soil salinity on the wheat and bean root respiration rate at low matric suctions

Water logging and salinity often occur together because rising water table brings salt to the surface. We studied the effects of a range of low soil matric suctions (or nearly paddy condition) (2–33 kPa) and salinity (EC = 0.7–8 dS m−1 for bean and 2–20 dS m−1 for wheat) on the root respiration (Rr) in two sandy loam and clay loam soils at greenhouse condition. Results showed that the aeration porosity mainly controls Rr especially at 2 kPa matric suction. As matric suction increases, soil aeration rises and consequently the Rr reaches maximum values (7.9 μmol m−3 s−1 for bean and wheat) at 6 and 10 kPa suctions in clay loam and sandy loam soils, respectively. Using a mechanistic soil respiration model reveals that these matric suctions, h, are corresponded to the aeration porosities of 0.18 m3 m−3 in sandy loam and 0.16 m3 m−3 in clay loam soils. Bean and wheat Rr remains nearly constant at higher suctions (h > 10 kPa) in sandy loam and decreases slightly in clay loam soil. Gas diffusivity and the root surface area may explain the variation of the Rr between the sandy loam and the clay loam soils. Results showed that the salinity (EC = 6–8 dS m−1 for bean and EC = 16–20 dS m−1 for wheat) amplifies the effect of aeration stress at 2 kPa matric suction in both soils. We also observed a strong correlation between root surface area, Rs, and the Rr for all experiments. We concluded that the aeration deficit is not only major factor determining differential plant respiration under adverse stress conditions, and the salinity has a pronounced impact on differences in crop physiological responses.

Improvement of Salt Tolerance in Durum Wheat (Triticum Durum Desf.) by Auxin and Kenitin Application

The aim of this work is to study the effect of soil salinity using different levels of NaCl (0, 10, 15 g/ NaCl) on some morphological and physiological properties of durum wheat (Triticum durum Desf.) var KEBIR in the vegetative stage. The results obtained allowed us to observe the negative impact of saline stress on the leaf area, Chlorophyll b, and carotenoids at moderate and higher salinity levels. The effect of salt on chlorophyll a content remains insignificant. On the other hand, proline content was highly affected by salt stress. It was excessively increased with the rise of osmotic stress levels, especially at higher salinity levels (15g/l NaCl). Phytohormones, such as auxin and cytokinin, are known to be involved in the regulation of plant responses to salinity stress. Also, it counteracts the adverse effect of stress conditions. Exogenous spraying of indole-3-acetic acid (IAA) and kinetin (K) with three various levels (10, 20, 30 p.p.m.), during the vegetative phase, indicated that an increase in the leaf area and pigments content are associated with a decrease in the proline content.

Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac) and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton

An increasing area of transgenic Bacillus thuringiensis (Bt) cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW) Helicoverpa armigera (Hübner) in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac) and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]). We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels.

Effects of soil salinity on the content, composition, and ion binding capacity of glomalin-related soil protein (GRSP).

Soil aggregation, an ecosystem function correlated with the concentration of glomalin-related soil protein (GRSP), is highly disturbed in saline soil. However, few studies have focused on differences in amount, composition, and ion binding capacity of GRSP in typical sodic-saline soils. In this study, a field study was performed in Songnen Plain. Combined indicators of soil salinity (Q value) were significant negatively correlated with GRSP concentration by Principal Component Analysis. Multiple linear regression models showed that soil salinity might account for 46%, 25% and 44% variation in total GRSP (T-GRSP), easily-extractable GRSP (EE-GRSP) and difficultly-extractable GRSP (DE-GRSP), respectively. Soil bulk density had most important impact on GRSP concentration, followed by the pH, soil EC had the weak influence. Comparative analysis was carried out between low-salinity and high-salinity soil. Purified T-GRSP of high-saline soil contained higher N content (13.13%), lower C content (43.41%) and lower functional groups relative content (e.g. CO and SiOSi). Purified T-GRSP of high-salinity soil had a greater binding capacity with calcium and phosphorus, the binding capacity could compensate the GRSP loss about 29.8% and 14.1%, respectively. Our findings suggested that sodic salinization of the soil led to a decrease in GRSP concentration and a change in the component percentages. This change in composition might be related to adaptation of fungi-plant systems to varied environments. The calcium and phosphorus binding capacity had a positive dependent of soil salinization, which was possible to develop ecological management or recovery technology in the future.

玛纳斯河流域盐渍化灌区生态环境遥感监测研究

PDF HTML阅读 XML下载 导出引用 引用提醒 玛纳斯河流域盐渍化灌区生态环境遥感监测研究 DOI: 10.5846/stxb201601310225 作者: 作者单位: 石河子大学,石河子大学,石河子大学 水利建筑工程学院,石河子大学理学院,石河子大学理学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41361073）；新疆研究生科研创新项目（XJGRI2015044） Assessment of soil salinization ecological environment change in the Manas river basin using remote sensing technology Author: Affiliation: Shihezi University,Shihezi University,School of Water Conservancy and Architecture Enginering, Shihezi University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤盐渍化已成为全球性问题，给生态环境及农业生产带来严重的威胁。为了快速、准确评价土壤盐渍化给区域生态坏境带来的影响，该文提出了新的完全基于遥感数据的遥感生态指数（SSEI，Soil Salinization Ecology Index）来监测玛纳斯河流域盐渍化灌区生态环境变化。该指数利用主成分分析的方法耦合与土壤盐渍化相关的土壤盐度、地表反照率、植被覆盖度和土壤湿度四大地表参数，指数构建是数据本身性质所决定，不同于以往遥感与非遥感指数加权叠加易受人为影响。研究结果表明：耦合与盐渍化信息相关的各遥感指数得到的生态指数，能够对土壤盐渍化影响区域的生态环境进行快速、定量、客观的监测。将该指数应用到新疆玛纳斯河流域灌区，结果表明在近26年优和良等级生态环境面积增加了12.89%，这说明灌区生态环境有所改善。该研究对土壤盐渍化监测与评价具有一定参考意义。 Abstract:Soil salinization has become a serious global problem, which poses a grave threat to ecological environment and agricultural production. In order to assess the effect of soil salinization on ecological environment quickly and accurately in regional-scale, a new remote sensing ecological index was proposed to detect the ecological change in arid area based on the remote sensing method in this paper. Manas river basin, a typical arid inland basin in northwest of China, was selected for the study area. Firstly, four indicators (salinity, surface albedo, vegetation coverage and wetness) which closely related to soil salinization were calculated based on the Landsat image in the Manas river basin on August 25, 1989, August 7, 2000, and September 10, 2015. Then, these indicators were normalized using min-max normalization method. Lastly, the principal component analysis (PCA) method was introduced to couple the four indicators, and the soil salinization ecology index (SSEI) was obtained. This method is different from the previous index overlaid by weighting the indexes from remote sensing and other data. It depends on the data itself, instead of subjective human states. The result shows that there is a significant relationship between SSEI and salt content observed in the fields (R2=0.9035, P < 0.01). This indicates SSEI could be used for retrieving the soil salinization on ecological environment rapidly and quantitatively. Through PCA analysis, we found that the first principal component appears stable and its share of all indicators is greater than 85%. The properties of wetness index (WI), normalized difference vegetation index (NDVI), and salinity index (SI) are consistent with the general ecological environmental parameters. The index was applied to the irrigated area of the Manas river basin. Among the bad, comparatively bad, medium, good, excellent grades, the area of bad grade had increased from 491.6 km2 to 1031.4 km2 during 1989 to 2000, but it has been decreased from 1031.4 km2 to 636.9 km2 during 2000 to 2015. The area of medium grade also increased at first but then reduced. The change area ranges from 6354.3 km2 in 1989 to 2111.4 km2 in 2015. The good and excellent grades of ecological environment has been increased by 12.9% in the last 26years, which shows the ecology environment has improved in the irrigation area. The spatial distribution of SSEI shows that the desert area without influencing by human activities still keeps a poor level, and the ecological problem is still very serious. The function of artificial oasis has been improving. Assessment of soil salinization ecological environment change using remote sensing technology could provide insight for land resource development in arid areas. 参考文献 相似文献 引证文献

Combined effects of soil salinity and high temperature on photosynthesis and growth of quinoa plants (Chenopodium quinoa).

The halophytic crop quinoa (Chenopodium quinoa Willd.) is adapted to soil salinity and cold climate, but recent investigations have shown that quinoa can be grown in significantly warmer latitudes, i.e. the Mediterranean region, where high temperature and soil salinity can occur in combination. In this greenhouse study, effects of saltwater irrigation and high temperature on growth and development of the Bolivian cultivar 'Achachino' were determined. Development was slightly delayed in response to saltwater treatment, but significantly faster at high temperature. Biomass and seed yield decreased in response to salt, but not to high temperature. Plants increased their number of stomata in response to salt stress, but reduced its size on both sides of the leaf, whereas high temperature treatment significantly increased the stomata size on the abaxial leaf surface. When salt and high temperature was combined, the size of stomata was reduced only on the abaxial side of the leaf, and the number of epidermal bladder cells significantly increased on the abaxial leaf surface, resulting in preservation of photosynthetic quantum yields. We hypothesise that this morphological plasticity improves the partition of water and CO2 resulting in maintenance of photosynthesis in quinoa under adverse environmental conditions. We present a GLM-model that predicts yield parameters of quinoa grown in regions affected by soil salinity, high temperature and the factors combined.

Influence of salicylic acid on ion distribution, enzymatic activity and some agromorphological characteristics of wheat under salt-affected soil

A Field Experiment carried out to examine the effects of soil salinity on morphological and physiological characters of two wheat cultivars differing in salt tolerance and the modulation of ion distribution and activities of antioxidant enzyme by exogenous application of salicylic acid under salt-affected soil. The experiment was designed in split plot design. Two wheat cultivars including Sakha93 (salt-tolerant) and Gemmiza9 (salt-sensitive) were assigned in main plots. Three levels of salicylic acid including (0, 100 and 200 mg L-1) were allocated to the subplots in 2013/2014 and 2014/2015 seasons. Salt-tolerant cultivar (Sakha93) showed higher morphological and physiological characters than salt sensitive one (Gemmiza9). Exogenous application of salicylic acid maintained lower Na+ concentration with higher K+/Na+ ratio in flag leaf blade in Sakha93 as compared to Gemmiza9. Exogenous application of salicylic acid increased K+ and decreased Na+ in Gemmiza9 as compared to untreated plants. Side by side, the improvement of ion distribution might be due to increment in activities of antioxidant enzymes catalase (CAT) and peroxidase (POX) by exogenous higher salicylic acid level (200 mg L-1) in 2013/2014 and 2014/2015 seasons. It could be concluded that exogenous application of 200 mg SA L-1 has effective impact in increasing yield-traits and grain yield under salt-affected soil condition.

Nitrogen Transportation and Transformation Under Different Soil Water and Salinity Conditions

Abstract Soil nitrogen transportation and transformation are important processes for crop growth and environmental protection, and they are influenced by various environmental factors and human interventions. This study aims to determine the effects of irrigation and soil salinity levels on nitrogen transportation and transformation using two types of experiments: column and incubation. The HYDRUS-1D model and an empirical model were used to simulate the nitrogen transportation and transformation processes. HYDRUS-1D performed well in the simulation of nitrogen transportation and transformation under irrigated conditions (R 2 as high as 0.944 and 0.763 for ammonium and nitrate-nitrogen simulations, respectively). In addition, the empirical model was able to attain accurate estimations for ammonium (R 2 = 0.512-0.977) and nitrate-nitrogen (R 2 = 0.410-0.679) without irrigation. The modelling results indicated that saline soil reduced the rate of urea hydrolysis to ammonium, promoted the longitudinal dispersity of nitrogen and enhanced the adsorption of ammonium-nitrogen. Furthermore, the effects of soil salinity on the nitrification rate were not obviously comparable to the effects of the amount of irrigation water. Without irrigation, the hydrolysis rate of urea to ammonium decreased exponentially with the soil salinity (R 2 = 0.787), although the nitrification coefficient varied with salinity. However, the denitrification coefficient increased linearly with salinity (R 2 = 0.499).

Absorption of nutrients by cowpea irrigated with saline water under different leaching fractions

ABSTRACT Salinity is one of the main environmental problems that negatively affect plant growth and metabolism, besides being one of the factors responsible for the decrease in the yield of crops, especially in arid and semiarid regions. Thus, the aim of this study was to evaluate the effects of soil salinity on the mineral nutrition of irrigated cowpea. The experiment was conducted in drainage lysimeters in a greenhouse, in a completely randomized design with seven treatments, one irrigated with freshwater (control) and six irrigated with saline water with different leaching fractions (5, 10, 15, 20, 30 and 40%) of the applied irrigation depth, with three replicates. The irrigation with saline water treatments did not affect significantly the contents of macronutrients and Na in the cowpea leaves, while the opposite behavior occurred with the micronutrients.

Effects of Salinity and Mycorrhizal Inoculation (Glomus fasciculatum) on Growth Responses of Grape Rootstocks (Vitis spp.)

A pilot experiment was conducted to determine the effects of soil salinity and inoculation with arbuscular mycorrhizal fungus (Glomus fasciculatum) on growth (shoot length, leaf number, internode length, and total dry weight), spore count and root colonisation of grape rootstocks (Salt Creek, St. George, Dogridge and 1613). Analysis of variance results revealed that increasing salinity reduces growth, spore count and root colonisation, with St. George rootstock showing the highest reduction. Although all rootstocks responded positively to mycorrhizal inoculation, the extent of host preference varied significantly. Dogridge was the least preferred, while the 1613 rootstock was the most preferred. The arbuscular fungal symbiosis increased vegetative growth, with 1613 attaining the highest growth under saline conditions. All the inoculated rootstocks exhibited longer internodes, indicating the beneficial role of mycorrhizal inoculation for improving plant growth and salt tolerance. Based on overall growth and total dry matter accumulation, the salt tolerance ranking of the four rootstocks, in decreasing order, was Dogridge, Salt Creek, 1613 and St. George.

Calibration of Gypsum Blocks for Measuring Saline Soils Moisture

ABSTRACTThe proper management of irrigation requires an accurate measuring of soil moisture. One of the commonly applied methods for measuring soil moisture is the use of gypsum blocks – a method that is simple and quick to apply. However, measuring moisture in saline soils using this method is prone to errors due to the effect of soil salinity on the block. In this study, the effect of different salinities (1, 2, 6, 10, and 18 deci Siemens per meter (dS m−1) on the measurements of a gypsum block type 5910 A was investigated with two repetitions in random blocks in sandy loam, loam, and clay loam soils, and corrective functions were obtained using multivariate regression for all soils with different salinity levels. The results showed different trends for measuring the soil moistures for salinities 1–6 dS m−1 compared with salinities 10–18 dS m−1, and the corrective functions in salinities 1–6 dS m−1, which had higher accuracies than those with salinities 10–18 dS m−1.

Predicting Near‐Surface Moisture Content of Saline Soils from Near‐Infrared Reflectance Spectra with a Modified Gaussian Model

Core Ideas Moisture estimates from near‐infrared reflectance are improved with a modified Gaussian model. Artificial neural network simulations further improve moisture prediction accuracy. The proposed method yields better results than standard reflectance moisture indices. Near‐surface soil moisture is a spatially highly heterogeneous state variable that affects the hydrologic partitioning of precipitation, net ecosystem exchange, and land–atmosphere interactions. In concert with the rapid advancement of large‐scale hyperspectral remote sensing technology over the last decade, numerous methods relating reflectance to near‐surface soil moisture have been proposed. Although there is evidence that surface reflectance is conjointly controlled by moisture and salt content, little is known about the impact of soil salinity. To study the effects of soil salinity, near infrared to short‐wave infrared reflectance spectra were measured in a controlled laboratory environment for samples representing a wide range of salinity levels. A previously proposed surface moisture prediction method based on geometrical attributes of an inverted Gaussian (IG) function fitted to hyperspectral reflectance curves was revisited. Improvements were proposed by first modifying the geometrical attributes of the IG applied to predict near‐surface soil moisture and by concurrently considering multiple geometrical attributes of the IG function as input for trained artificial neural networks (ANNs). Although previously applied linear regression models that relate a single geometrical parameter to soil moisture failed to satisfactorily predict independently measured surface soil moisture, considerable improvements in prediction accuracy were achieved with both geometrical attribute modification and ANN simulations.

Effects of Soil Salinity on Tocopherols, Tocotrienols, and γ‐Oryzanol Accumulation and their Relation to Oxidative Stress in Rice Plants

Tocopherols (Toc), tocotrienols (T3), and γ‐oryzanol (GO) are major bioactive compounds of rice that have been known to possess various pharmacological properties. Understanding the stress effects on the accumulation of these compounds may aid in the improvement of rice grain quality. In this study, our aim was to examine the effects of soil salinity on Toc, T3 and GO contents, as well as their role in antioxidant status in rice plants. Four levels of salinity treatments with electrical conductivity values of 0, 2, 4, and 8 dS m−1 were conducted during the reproductive stage of rice (95 d after transplanting). Compared with the control, results showed that salinity treatments significantly increased the contents of total T3, α‐Toc, α‐T3, and γ‐T3 in the rice grains; however, there was no difference in the content of total Toc. Under high salinity (electrical conductivity value 8 dS m−1) conditions, GO concentration increased significantly in the grains while that of γ‐Toc decreased. Salinity treatments caused malondialdehyde content to increase in the rice straws, while H2O2 level was not affected. Increasing salinity led to a significant decrease in ascorbate concentration in the rice straws and grains, and enhanced superoxide dismutase, ascorbate peroxidase, and catalase activities in the rice straws; however, the enzymatic antioxidant activities in the rice grains were lower as compared with the control group. This study suggests that moderate increases in soil salinity can enhance T3 and GO accumulation in the rice grains.

Halotolerant Plant Growth Promoting Bacteria Mediated Salinity Stress Amelioration in Plants

Soil salinization refers to the buildup of salts in soil to a level toxic to plants. The major factors that contribute to soil salinity are the quality, the amount and the type of irrigation water used. The presented review discusses the different sources and causes of soil salinity. The effect of soil salinity on biological processes of plants is also discussed in detail. This is followed by a debate on the influence of salt on the nutrient uptake and growth of plants. Salinity decreases the soil osmotic potential and hinders water uptake by the plants. Soil salinity affects the plants K uptake, which plays a critical role in plant metabolism due to the high concentration of soluble sodium (Na + ) ions. Visual symptoms that appear in the plants as a result of salinity include stunted plant growth, marginal leaf necrosis and fruit distortions. Different strategies to ameliorate salt stress globally include breeding of salt tolerant cultivars, irrigation to leach excessive salt to improve soil physical and chemical properties. As part of an ecofriendly means to alleviate salt stress and an increasing considerable attention on this area, the review then focuses on the different plant growth promoting bacteria (PGPB) mediated mechanisms with a special emphasis on ACC deaminase producing bacteria. The various strategies adopted by PGPB to alleviate various stresses in plants include the production of different osmolytes, stress related phytohormones and production of molecules related to stress signaling such as bacterial 1-aminocyclopropane-1-carboxylate(ACC) derivatives. The use of PGPB with ACC deaminase producing trait could be effective in promoting plant growth in agricultural areas affected by different stresses including salt stress. Finally, the review ends with a discussion on the various PGPB activities and the potentiality of facultative halophilic/halotolerant PGPB in alleviating salt stress.

Effect of salinity and soil temperature on the growth and physiology of drip-irrigated rice seedlings

ABSTRACTDrip irrigation offers potential for rice (Oryza sativa L.) production in regions where water resources are limited. However, farmers in China’s Xinjiang Province report that drip-irrigated rice seedlings sometimes suffer salt damage. The objective of this study was to learn more about the effects of soil salinity and soil temperature on the growth of drip-irrigated rice seedlings. The study consisted of a two-factor design with two soil salinity treatments (0 and 1.8 g kg−1 NaCl) and three soil temperature treatments (18°C, 28°C and 36°C). The results showed that shoot biomass, root biomass and root vigor were greatest when seedlings were grown with no salt stress (0 g kg−1 NaCl) at 28°C. Moderate salt stress (1.8 g kg−1 NaCl) combined with high temperature (36°C) significantly reduced root and shoot biomass by 39–53%. Moderate salt stress and high temperature also increased root proline concentration by 77%, root malonyldialdehyde concentration by 60% and seedling mortality by 60%. Shoot and root Na+ concentrations, shoot and root Na+ uptake and the Na+ distribution ratio in shoots were all the greatest when moderate salt stress was combined with high temperature. In conclusion, high soil temperature aggravates salt damage to drip-irrigated rice seedlings. Therefore, soil salinity should be considered before adopting drip-irrigation for rice production.

A meta‐analysis of soil salinization effects on nitrogen pools, cycles and fluxes in coastal ecosystems

Salinity intrusion caused by land subsidence resulting from increasing groundwater abstraction, decreasing river sediment loads and increasing sea level because of climate change has caused widespread soil salinization in coastal ecosystems. Soil salinization may greatly alter nitrogen (N) cycling in coastal ecosystems. However, a comprehensive understanding of the effects of soil salinization on ecosystem N pools, cycling processes and fluxes is not available for coastal ecosystems. Therefore, we compiled data from 551 observations from 21 peer-reviewed papers and conducted a meta-analysis of experimental soil salinization effects on 19 variables related to N pools, cycling processes and fluxes in coastal ecosystems. Our results showed that the effects of soil salinization varied across different ecosystem types and salinity levels. Soil salinization increased plant N content (18%), soil NH4+ (12%) and soil total N (210%), although it decreased soil NO3- (2%) and soil microbial biomass N (74%). Increasing soil salinity stimulated soil N2 O fluxes as well as hydrological NH4+ and NO2- fluxes more than threefold, although it decreased the hydrological dissolved organic nitrogen (DON) flux (59%). Soil salinization also increased the net N mineralization by 70%, although salinization effects were not observed on the net nitrification, denitrification and dissimilatory nitrate reduction to ammonium in this meta-analysis. Overall, this meta-analysis improves our understanding of the responses of ecosystem N cycling to soil salinization, identifies knowledge gaps and highlights the urgent need for studies on the effects of soil salinization on coastal agro-ecosystem and microbial N immobilization. Additional increases in knowledge are critical for designing sustainable adaptation measures to the predicted intrusion of salinity intrusion so that the productivity of coastal agro-ecosystems can be maintained or improved and the N losses and pollution of the natural environment can be minimized.

Effect of Funneliformis mosseae on growth, mineral nutrition, biochemical indexes and chlorophyll content of Ziziphus spina-christi seedlings at different salinities

Vast area of the land around the world is saline. Knowledge of plant behavior and their interaction with mychorrizal fungi in saline areas may help seedling establishment in such environments. This study aimed to determine the effects of the inoculation of the fungus Funneliformis mosseae (FM) on Ziziphus spina-christi (Rhamnaceae) plants grown under salt stress. Mycorrhizal and non-mycorrhizal seedlings were exposed to different levels of NaCl in the soil (0, 50, 100, and 150 mM). The following parameters were measured in both inoculated and non-inoculated plants: root colonization rate, seedling height, root diameter, root and shoot dry weights, chlorophyll a and b, total nitrogen (N), phosphorus (P), potassium (K) and sodium (Na+) content, proline accumulation in roots and leaves, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities. The results showed that soil salinity hampered the root colonization by the fungus, and decreased basal diameter, seedling height, root and shoot dry weights, as well as some nutrients and chlorophyll a concentration, while increased leaves and roots Na+, SOD and POD activity, proline accumulation, as well as CAT activity in the roots. Contrastingly, no significant effect of soil salinity were detected on K and CAT of leaves, root N, and chlorophyll b. Inoculated plants had higher basal diameter, leaves and roots P, root and shoot dry weights, chlorophyll a and lower SOD content, proline accumulation in leaves and Na+, as compared with non-inoculated plants. Seedling height, root N, CAT and POD content, and chlorophyll b were not affected by inoculation with FM. These results demonstrated that FM inoculation is a promising method for improving the growth of Z. spina-christi seedlings under salt stress.

Effects of Soil Salinity on Sucrose Metabolism in Cotton Leaves.

This study investigated sucrose metabolism of the youngest fully expanded main-stem leaf (MSL) and the subtending leaf of cotton (Gossypium hirsutum L.) boll (LSCB) of salt-tolerant (CCRI-79) and salt-sensitive (Simian 3) cultivars and its relationship to boll weight under low, medium and high soil salinity stress in Dafeng, China, in 2013 and 2014. The results showed that with increased soil salinity, 1) both the chlorophyll content and net photosynthetic rate (Pn) decreased, while the internal CO2 concentration firstly declined, and then increased in the MSL and LSCB; 2) carbohydrate contents in the MSL reduced significantly, while sucrose and starch contents in the LSCB increased, as did the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) in both the MSL and LSCB; 3) but invertase activity in both the MSL and LSCB did not change significantly. Our study also showed that the LSCB was more sensitive to soil salinity than was the MSL. Of the measured physiological indices, higher SPS activity, mainly controlled by sps3, may contribute to adaption of the LSCB to soil salinity stress because SPS is beneficial for efficiently sucrose synthesis, reduction of cellular osmotic potential and combined actions of Pn, and sucrose transformation rate and SPS may contribute to the reduction in boll weight under soil salinity stress.

Effects of Soil Salinity on Sucrose Metabolism in Cotton Fiber.

Cotton (Gosspium hirsutum L.) is classified as a salt tolerant crop. However, its yield and fiber quality are negatively affected by soil salinity. Studies on the enzymatic differences in sucrose metabolism under different soil salinity levels are lacking. Therefore, field experiments, using two cotton cultivars, CCRI-79 (salt-tolerant) and Simian 3 (salt-sensitive), were conducted in 2013 and 2014 at three different salinity levels (1.15 dS m-1 [low soil salinity], 6.00 dS m-1 [medium soil salinity], and 11.46 dS m-1 [high soil salinity]). The objective was to elucidate the effects of soil salinity on sucrose content and the activity of key enzymes that are related to sucrose metabolism in cotton fiber. Results showed that as the soil salinity increased, cellulose content, sucrose content, and sucrose transformation rate declined; the decreases in cellulose content and sucrose transformation rate caused by the increase in soil salinity were more in Simian 3 than those in CCRI-79. With increase in soil salinity, activities of sucrose metabolism enzymes sucrose phophate synthase (SPS), acidic invertase, and alkaline invertase were decreased, whereas sucrose synthase (SuSy) activity increased. However, the changes displayed in the SuSy and SPS activities in response to increase in soil salinity were different and the differences were large between the two cotton cultivars. These results illustrated that suppressed cellulose synthesis and sucrose metabolism under high soil salinity were mainly due to the change in SPS, SuSy, and invertase activities, and the difference in cellulose synthesis and sucrose metabolism in fiber for the two cotton cultivars in response to soil salinity was determined mainly by both SuSy and SPS activities.