Antioxidant Activity in Salt‐Stressed Barley Leaves: Evaluating Time‐ and Age‐Dependence and Suitability for the Use as a Biochemical Marker in Breeding Programs

Soil salinity disturbs the equilibrium between reactive oxygen species (ROS) production and removal, leading to a dramatic increase in ROS concentration and oxidative damage. Enzymatic scavenging is one of the two main mechanisms involved in ROS detoxification in plants. This study has investigated the role of major antioxidant (AO) enzymes in mitigating salinity‐induced oxidative stress in plant shoots. Firstly, two barley varieties were used to evaluate the activity of major AO enzymes in different leaves and at different times after salt treatment. Our results showed that AO enzyme activities had strong tissue and time specificity. A further study was conducted using six barley varieties contrasting in salinity tolerance. AO enzyme activities and proline contents were measured in the third leaves of seedlings after plants were treated with 240 mm NaCl for 10 days. No significant correlation was revealed between leaf AO activity and either plant grain yield or plant survival rate under salt stress. In contrast, a significant increase in leaf proline content under salt stress was found in all sensitive varieties, while in most tolerant varieties, salt stress did not change leaf proline level. It is concluded that although salinity induces changes in leaf AO enzyme activities, the changes cannot be used as biochemical indicators in breeding for salinity tolerance.     

Saponin seed priming improves salt tolerance in quinoa

Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte of great value, and World Health Organization has selected this crop, which may assure future food and nutritional security under changing climate scenarios. However, germination is the main critical stage of quinoa plant phenology affected by salinity. Therefore, two experiments were conducted to improve its performance under salinity by use of saponin seed priming. Seeds of cv. Titicaca were primed in seven different solutions with varying saponin concentrations (i.e. 0%, 0.5%, 2%, 5%, 10%, 15%, 25% and 35%), and then, performances of primed seeds were evaluated based on mean germination time and final germination percentage in germination assays (0 and 400 mM NaCl stress). Saponin solutions of 10%, 15% and 25% concentration were found most effective priming tools for alleviating adverse effects of salt stress during seed germination. Performances of these primed seeds were further evaluated in pot study. At six‐leaf stage, plants were irrigated with saline water having either 0 or 400 mM NaCl. The results indicated that saline irrigation significantly decreased the growth, physiology and yield of quinoa, whereas saponin priming found operative in mitigating the negative effects of salt stress. Improved growth, physiology and yield performance were linked with low ABA concentration, better plant water (osmotic and water potential) and gas relations (leaf photosynthetic rate, stomatal conductance), low Na⁺ and high K⁺ contents in leaves. Our results suggest that saponin priming could be used as an easy‐operated and cost‐effective technology for sustaining quinoa crop growth on salt‐affected soils.     

Reduced Sink Activity in Growing Shoot Tissues of Maize under Salt Stress of the First Phase may be Compensated by Increased PEP‐Carboxylase Activity

The effects of salt stress (100 mm NaCl for 6 days) on growing tissues (shoot apex, growing leaf segments, root tips) of young maize plants (Zea mays L. cv. Pioneer 3906) were investigated in comparison to an unsalinized control, focusing on assimilate supply from source leaves and the activity of sucrolytic enzymes in the sink tissues. The objectives were to test whether (i) phloem unloading in growing tissues is mainly symplastic, (ii) salinity reduces sink activity, determined either as sucrose synthase activity (indicator for the symplastic pathway) or as acid invertase activity (indicator for the apoplastic pathway), and (iii) PEP‐carboxylase activity is increased under salinity to compensate for reduced sink activity. For growing tissues of young maize shoots, it can be assumed that phloem transport of sucrose is mainly driven by symplastic unloading into the sink cells. In maize root tips, both, apoplastic and symplastic pathways, contributed to carbohydrate supply to the sink cells. The activity of acid invertase in growing shoot tissues was very low, and the alkaline invertase contributed less than 10 % to the cytoplasmic sucrolytic activity. Salt stress of the first phase (mainly osmotic stress) caused a significant inhibition of acid invertase activity in the growing leaf segments and in the root tips, which was also true for alkaline invertase activity in the root tips as well as for sucrose synthase activity in root tips and shoot apex. The decrease of sucrose synthase activity in shoot apex might be particularly detrimental for the plant growth, as this tissue with a high cell division rate relied entirely on cytoplasmic enzyme activities. Under salt stress, PEP carboxylase activity was significantly increased in growing leaves and the shoot apex of maize, whereas no significant effect was observed in the root apex. In conclusion, PEP carboxylase can have an anaplerotic function supporting the demand for metabolites in growing shoot tissues of young maize plants under salt stress. In root tips, an additional supply of organic acids to the tricarboxylic acid cycle is probably not needed, as sucrolytic sink activity, which was high even under saline conditions, can meet the demand of the sink cells.     

Genetic variation in root development responses to salt stresses of quinoa

Soil salinity has become a serious environmental abiotic stress limiting crop productivity and quality. The root system is the first organ sensing the changes in salinity. Root development under elevated salinity is therefore an important indicator for saline tolerance in plants. Previous studies focused on varietal differences in morphological traits of quinoa under saline stresses; however, variation in root development responses to salinity remains largely unknown. To understand the genetic variation in root development responses to salt stress of quinoa, we conducted a preliminary screening for salinity response at two salinity levels of a diverse set of 52 quinoa genotypes and microsatellite markers were used to link molecular variation to that in root development responses to salt stresses of represented genotypes. The frequency distribution of saline tolerance index showed continuous variation in the quinoa collection. Cluster analysis of salinity responses divided the 52 quinoa genotypes into six major groups. Based on these results, six genotypes representative of groups I to VI including Black quinoa, 2-Want, Atlas, Riobamba, NL-6 and Sayaña, respectively, were selected to evaluate root development under four saline stress levels: 0, 100, 200 and 300 mM NaCl. Contrasts in root development responses to saline stress levels were observed in the six genotypes. At 100 mM NaCl, significant differences were not observed in root length development (RLD) and root surface development (RSAD) of most genotypes except Black quinoa; a significant reduction was observed in this genotype as compared to controls. At 200 mM NaCl, significant reduction was detected in RLD and RSAD in all genotypes showing this as the best concentration to discriminate among genotypes. The strongest inhibition of root development was found for all genotypes at 300 mM NaCl as compared to lower saline levels. Among genotypes, Atlas of group III shows as a saline-tolerant genotype confirming previous reports. Variation in root responses to salinity stresses is also discussed in relation to climate conditions of origins of the genotypes and reveal interesting guidelines for further studies exploring the mechanisms behind this aspect of saline adaptation.     

Growth and Ionic Content of Quinoa Under Saline Irrigation

Drought and salinity are the most important abiotic stresses that affect plant's growth and productivity. The aim of the present work was to evaluate the effect of salt and water deficit on water relations, growth parameters and capacity to accumulate inorganic solutes in quinoa plants. An irrigation experiment was carried out in 2009 and 2010 in the Volturno river plain. Three treatments irrigated with fresh water (Q100, Q50 and Q25) and three irrigated with saline water (Q100S, Q50S and Q25S) were tested. For saline irrigation, water with an electrical conductivity of 22 dS m^?1 was used. Actual evapotranspiration (ET_a), water productivity (WP), biomass allocation, relative growth rate (RGR), net assimilation rate (NAR), specific leaf area, leaf area ratio and ions accumulation of quinoa plants were evaluated. WP and plant growth were not influenced by saline irrigation, as quinoa plants incorporated salt ions in the tissues (stems, roots, leaves) preserving seed quality. Treatment with a reduction in the irrigation water to 25 % of full irrigated treatment (Q25) caused an increase in WP and a reduced dry matter accumulation in the leaves. Quinoa plants (Q25) were initially negatively affected by severe drought with RGR and NAR reduction, and then, they adapted to it. Quinoa could be considered a drought tolerant crop that adapt photosynthetic rate to compensate for a reduced growth.     

Salt Tolerance is Associated with Differences in Ion Accumulation,Biomass Allocation and Photosynthesis in Cowpea Cultivars

Cowpea is widely cultivated in arid and semi‐arid regions of the world where salinity is a major environmental stress that limits crop productivity. The effects of moderate salinity on growth and photosynthesis were examined during the vegetative phase of two cowpea cultivars previously classified as salt‐tolerant (Pitiúba) and salt‐sensitive (TVu). Two salt treatments (0 and 75 mm NaCl) were applied to 10‐day‐old plants grown in nutrient solution for 24 days. Salt stress caused decreases (59 % in Pitiúba and 72 % in TVu) in biomass accumulation at the end of the experiment. Photosynthetic rates per unit leaf mass, but not per unit leaf area, were remarkably impaired, particularly in TVu. This response was unlikely to have resulted from stomatal or photochemical constraints. Differences in salt tolerance between cultivars were unrelated to (i) variant patterns of Cl^? and K⁺ tissue concentration, (ii) contrasting leaf water relations, or (iii) changes in relative growth rate and net assimilation rate. The relative advantage of Pitiúba over TVu under salt stress was primarily associated with (i) restricted Na⁺ accumulation in leaves paralleling an absolute increase in Na⁺ concentration in roots at early stages of salt treatment and (ii) improved leaf area (resulting from a larger leaf area ratio coupled with a larger leaf mass fraction and larger specific leaf area) and photosynthetic rates per unit leaf mass. Overall, these responses would allow greater whole‐plant carbon gain, thus contributing to a better agronomic performance of salt‐tolerant cowpea cultivars in salinity‐prone regions.     

The Effects of Foliar Application of Ascorbic Acid (Vitamin C) on Antioxidant Enzymes Activities, Lipid Peroxidation and Proline Accumulation of Canola (Brassica napus L.) under Conditions of Salt Stress

The effects of salt stress on protein (PROT) content, lipid peroxidation, proline accumulation, chlorophyll (Chl) content, and superoxide dismutase (SOD; EC 1.15.1.1), catalase (EC 1.11.1.6) and peroxidase (EC 1.11.1.7) activity were studied in the leaves and roots of canola (Brassica napus L. cv. Okapi). Four weeks after sowing (at the V₄ stage), plants were exposed to salt stress by the application of NaCl solution (200 mm ) for 6 days daily, After 6 days followed by foliar application of ascorbic acid (AsA) solution (25 mm ). The activity of all the antioxidant enzymes assayed (except SOD in the roots) was increased significantly in the plants under conditions of salt stress. The application of AsA decreased enzyme activity in the leaves, but it had no effect on enzyme activity in the roots. The total PROT content of the leaves and roots decreased under the conditions of high salinity. AsA treatment of plants under salt stress increased the total PROT content significantly in both leaves and roots. Measurement of the malondialdehyde content of leaves and roots showed that lipid peroxidation was increased by interaction with damaging reactive oxygen species during salt stress, and that application of AsA reduced lipid peroxidation only in the leaves. The Chl content was also affected by salt stress. There was significant difference between the controls and salt‐stress treatments in Chl content. The results of the present study indicate that usage of AsA reduces the harmful effects of salinity and increases resistance to salinity in canola plant.     

外源一氧化氮供体对盐胁迫下小麦幼苗叶片谷胱甘肽抗氧化酶系统的影响

研究了外源一氧化氮（NO）供体SNP对150 mmol/L NaCl胁迫下小麦幼苗叶片谷胱甘肽抗氧化酶系统的影响。结果表明，与单独盐胁迫相比，0.1 mmol/L的SNP处理明显提高了小麦幼苗叶片还原型谷胱甘肽（GSH）的含量，略微降低了氧化型谷胱甘肽（GSSG）的含量，明显提高了GSH/GSSG，这可能与其诱导谷胱甘肽还原酶（GR）的活性有部分关     

多效唑、烯效唑对油菜‘秦优1618’苗期特性和抗寒性的影响

为探索多效唑和烯效唑对油菜新品种‘秦优1618’抗寒性的影响,采用多效唑150 mg/L(C1)、300 mg/L(C2),烯效唑80 mg/L(C3)、160 mg/L(C4)喷施6~7叶期油菜幼苗1次,研究多效唑和烯效唑对幼苗生长调控、生理特性和抗寒性的影响。结果显示：采用多效唑150 mg/L(C1)或烯效唑80 mg/L(C3)处理6~7叶期幼苗,可有效降低苗期薹茎高、茎叶干质量、最大叶长度和宽度,对绿叶数影响不显著,有效提高根茎粗、根长、侧根数、根干质量和根冠比,形成壮苗;同时可增加叶片叶绿素和可溶性糖含量,降低相对电导率,提高叶片净光合速率,降低越冬死亡株率和冻害指数,提高抗寒性。     

Antioxidative Response of Quinoa Exposed to Iso‐Osmotic,Ionic and Non‐Ionic Salt Stress

Antioxidants play an important role in adapting plants to abiotic stress by detoxifying reactive oxygen species (ROS). Involvement of antioxidant enzymes in abiotic stress tolerance of highly stress‐tolerant quinoa was studied in a climatic chamber at 6 mOsm (milliosmolar) ionic (300 mm NaCl) and non‐ionic (600 mm mannitol) salts combined with increasing levels of potassium K1 and K2 (6, 12 mm ), respectively. Fifteen days of salt treatment (both ionic and non‐ionic) decreased plant growth (shoot and root fresh weight), stomatal conductance and chlorophyll content index. Furthermore, both forms of salt stress increased the activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase up to 2.33‐, 3.98‐, 4.78‐ and 5.55‐folds, respectively, compared to no salt treatment, whereas membrane stability index decreased corresponding to increase in lipid peroxidation (malondialdehyde), with salt treatments compared to non‐stressed plants. However, no significant effect of potassium and salt treatments has been noticed on the maximal photochemical efficiency of PSII. The results suggested that enhanced antioxidant enzymes activity under salt stress could be one of the factors responsible for abiotic stress tolerance in quinoa.     

Growth Properties and Ion Distribution in Different Tissues of Bread Wheat Genotypes (Triticum aestivum L.) Differing in Salt Tolerance

Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na⁺), potassium (K⁺) concentrations and K⁺/Na⁺ ratio in different tissues including root, leaf‐3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt‐tolerant genotypes (Karchia‐65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt‐sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na⁺‐specific effects within the plant. Grain yield loss in salt‐tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt‐sensitive ones was due to decline in grain number. Salt‐tolerant genotypes sequestered higher amounts of Na⁺ concentration in root and flag leaf sheath and maintained lower Na⁺ concentration with higher K⁺/Na⁺ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.     

Effect of NaCl Salinity and Putrescine on Shoot Growth, Tissue Ion Concentration and Yield of Rice (Oryza sativa L. var. GR-3)

Interactive effect of NaCl salinity and putrescine on shoot growth, ion (Na⁺, K⁺ and CI⁻) concentration in leaf, stem and inflorescence and yield of rice (Oryza sativa L. var. GR-3) were studied. When rice plants were subjected to salt stress (12 dS/m) the extension growth and dry weight of shoot system as well as total leaf area and chlorophyll content were found markedly reduced. Analysis of leaf, stem and inflorescence of salt-stressed plants showed higher concentration of Na⁺ and Cl ions and lower concentration of K⁺ ion compared to the control. Salinization also caused a considerable fall in grain yield.
Foliar application of putrescine (10⁻⁵M) significantly increased the growth and yield of salt-stressed plants. Putrescine treatment decreased the influx of Na⁺ and Cl⁻ ions and increased the K⁺ level in all the tissues of salinized plants examined. Putrescine also increased the chlorophyll content in salt-stressed plants. These results suggest that exogenous application of putrescine can be used successfully to ameliorate the stress injuries caused by NaCl salinity in rice plants to a considerable extent.     

SHORT COMMUNICATION: Effect of Salt Stress on Peruvian Germplasm of Chenopodium quinoa Willd.: A Promising Crop

Soil salinity is a major problem in today’s agriculture. Quinoa has become an important crop because it exhibits high levels of salinity tolerance. In addition, its seeds contain an excellent balance of carbohydrates, lipids, amino acids and proteins for human nutrition. The quinoa germplasm includes almost 2500 accessions, some of which have been tested under salt stress. Here, we report the effect of NaCl on the germination of 182 previously untested accessions. When seeds were irrigated with saline water at 30 dS m^?1 EC, the stress appeared to be too high: all accessions showed less than 60 % germination. In contrast, irrigation with 25 dS m^?1 EC saline water allowed over 60 % germination in 15 accessions. These latter accessions’ agricultural traits were then evaluated. The overall coefficients of variation indicated that quinoa genotype and salt treatment dramatically influence root dry mass per plant, but do not noticeably affect the length of the plant’s life cycle. Unexpectedly, salt treatment resulted in increased plant height, leaf dry mass and grain yield. Using Euclidean distance for the simultaneous selection of these five agricultural traits, accessions 100, 136, 127 and 105 proved to be the best performing genotypes under salt stress.     

Oxidative stress indicators as selection tools for salt tolerance

Oxidative stress indicators, malondialdehyde (MDA) accumulation and chlorophyll retention, were tested as tools for salt‐tolerance screening in Chloris gayana (Kunth), a forage grass exhibiting inter‐ and intra‐cultivar variability in the response to salt stress. Three types of experimental system were compared, salt shock, gradual salt treatment and leaf segments floated on control and saline solutions. Results followed the same trend in the three systems, but leaf segments or gradually salinized plants are the most convenient. Lower mean MDA and higher mean chlorophyll content were found under salinity in cv. ‘Katambora’, which is considered, from previous field trials, to be more salt tolerant than cv. ‘Boma’. Nevertheless, chlorophyll content did not give consistent results in other tests and it is not recommended for selection purposes. Within cv. ‘Boma’, clones rating higher in a salt tolerance evaluation under greenhouse conditions had lower MDA content under salinity and lower mean MDA ratios between salt‐treated and control samples. The survival of 80‘Boma’ plants under increasing NaCl concentration was assessed and MDA was measured in the leaves of very plant before the final NaCl level was reached, to assess whether it was predictive of survival capability. MDA values were significantly lower in the group surviving longer, thus, a selection based on low MDA values would have enriched the original population with more tolerant individuals.     

Role of Arbuscular Mycorrhizae in the Alleviation of Ionic, Osmotic and Oxidative Stresses Induced by Salinity in Cajanus cajan (L.) Millsp. (pigeonpea)

Salinity stress causes ion toxicity and osmotic imbalances, leading to oxidative stress in plants. Arbuscular mycorrhizae (AM) are considered bio‐ameliorators of saline soils and could develop salinity tolerance in crop plants. Pigeonpea exhibits strong mycorrhizal development and has a high mycorrhizal dependency. The role of AM in enhancing salt tolerance of pigeonpea in terms of shoot and root dry weights, phosphorus and nitrogen contents, K⁺ : Na⁺, Ca²⁺ : Na⁺ ratios, lipid peroxidation, compatible solutes (proline and glycine betaine) and antioxidant enzyme activities was examined. Plants were grown and maintained at three levels of salt (4, 6 and 8 dSm^?1). Stress impeded the growth of plants, led to weight gain reductions in shoots as well as roots and hindered phosphorus and nitrogen uptake. However, salt‐stressed mycorrhizal plants produced greater root and shoot biomass, had higher phosphorus and nitrogen content than the corresponding uninoculated stressed plants. Salt stress resulted in higher lipid peroxidation and membrane stability was reduced in non‐AM plants. The presence of fungal endophyte significantly reduced lipid peroxidation and membrane damage caused by salt stress. AM plants maintained higher K⁺ : Na⁺ and Ca²⁺ : Na⁺ ratios than non‐AM plants under stressed and unstressed conditions. Salinity induced the accumulation of both proline and glycine betaine in AM and non‐AM plants. The quantum of increase in synthesis and accumulation of osmolytes was higher in mycorrhizal plants. Antioxidant enzyme activities increased significantly with salinity in both mycorrhizal and non‐mycorrhizal plants. In conclusion, pigeonpea plants responded to an increased ion influx in their cells by increasing the osmolyte synthesis and accumulation under salt stress, which further increased with AM inoculation and helped in maintaining the osmotic balance. Increase in the antioxidant enzyme activities in AM plants under salt stress could be involved in the beneficial effects of mycorrhizal colonization.     

Effect of Salinity Stress on Growth and Nutrient Composition of Three Soybean (Glycine max L. Merrill) Cultivars

Soil salinity is a major limitation to legume production in many areas of the world. The salinity sensitivity of soybean was studied to determine the effect of salinity on seed germination, shoot and root dry weights, and leaf mineral contents. Three soybean cultivars, Lee, Coquitt, and Clark 63, were planted in soils of different salinity levels. The electrical conductivity (EC) of the soils used in this experiment was 0.5 dS m^?1. The soil salinity treatments were 0.5, 2.5 4.5, 6.5 and 8.5 dS m^?1. Saline drainage water from a drainage canal with an EC of 15 dS m^?1 was used to treat the soil samples in order to obtain the desired salinity levels. Germination percentages were recorded 10 days after planting. Shoot and root dry weights of 45‐day‐old plants were measured. Nutrient concentrations for Na⁺, K⁺, Ca²⁺, Mg²⁺ and Cl^? were determined. Germination percentages were significantly reduced with increasing salinity levels. The cultivar Lee was less affected by salinity stress than Coquitt and Clark 63. At 8.5 dS m^?1 a significant reduction in plant height was found in all three cultivars. However, Lee plants were taller than plants of the other two cultivars. Salinity stress induced a significant increase in leaf sodium (Na⁺) and chloride (Cl^?) in all cultivars. However, the cultivar Lee maintained lower Na⁺ and Cl⁺ concentrations, a higher potassium (K⁺) concentration and a higher K⁺/Na⁺ ratio at higher salinity levels than Coquitt and Clark 63. Saline stress reduced the accumulation of K⁺, calcium (Ca²⁺) and magnesium (Mg²⁺) in the leaves of the cultivars studied. This study suggests that Lee is the most tolerant cultivar, and that there is a relationship between the salt tolerance of the cultivar and macronutrient accumulation in the leaves.     

Biochar Mitigates Salinity Stress in Potato

A pot experiment was conducted in a climate‐controlled greenhouse to investigate the growth, physiology and yield of potato in response to salinity stress under biochar amendment. It was hypothesized that addition of biochar may improve plant growth and yield by mitigating the negative effect of salinity through its high sorption ability. From tuber bulking to harvesting, the plants were exposed to three saline irrigations, that is 0, 25 and 50 mm NaCl solutions, respectively, and two levels of biochar (0 % and 5 % W/W) treatments. An adsorption study was also conducted to study the Na⁺ adsorption capability of biochar. Results indicated that biochar was capable to ameliorate salinity stress by adsorbing Na⁺. Increasing salinity level resulted in significant reductions of shoot biomass, root length and volume, tuber yield, photosynthetic rate (A_n), stomatal conductance (g_s), midday leaf water potential, but increased abscisic acid (ABA) concentration in both leaf and xylem sap. At each salinity level, incorporation of biochar increased shoot biomass, root length and volume, tuber yield, A_n, g_s, midday leaf water potential, and decreased ABA concentration in the leaf and xylem sap as compared with the respective non‐biochar control. Decreased Na⁺, Na⁺/K⁺ ratio and increased K⁺ content in xylem with biochar amendment also indicated its ameliorative effects on potato plants in response to salinity stress. The results suggested that incorporation of biochar might be a promising approach for enhancing crop productivity in salt‐affected soils.     

PAM施用深度对盐碱胁迫下藜麦生长及生理指标的影响

以陇藜4号为试验材料，采用根管土柱栽培试验，设置轻度(S1,3g/kg)、中度(S2,5g/kg)和重度盐碱胁迫(S3,7g/kg)以及土壤调理剂聚丙烯酰胺(PAM)施用深度0～10(PAM₀)、10～20(PAM₁₀)、20～30(PAM₂₀)和0～30cm(PAM₃₀)的完全随机试验组合，以土壤中不加盐碱和PAM为对照组(S0)，共计13个处理组合，研究PAM施用深度对不同盐碱胁迫条件下藜麦生长及生理指标的影响。结果表明，盐碱胁迫处理和PAM施用深度处理均会对藜麦的形态指标和生理指标造成显著影响：在合理施用PAM的前提下，与对照相比，轻度盐胁迫反而更有利于藜麦的生长，甚至中度盐胁迫下藜麦生长也没受到显著影响，表明藜麦具有较强的耐盐性。当盐碱胁迫达到重度(S3)时，虽然不同PAM施用浓度对藜麦生长有一定影响，但与对照相比，盐碱胁迫均显著抑制了藜麦地上部的生长；不同盐碱胁迫条件下不同PAM施用方式对藜麦生长及生理指标的影响均表现为PAM₀处理的效果最佳。隶属函数结果表明，不同处...     

大麻二酚对Cd和Cr胁迫下烟草生长的影响

为探讨大麻二酚(CBD)对重金属胁迫下烟草生长的影响,以烟草品种K326为材料,分别将浓度为0.0、1.0、5.0、25.0mg/L的CBD喷施于Cd和Cr胁迫烟株叶面,测定其叶片的抗氧化指标、生物量及Cd、Cr积累量。结果表明,Cd和Cr胁迫严重抑制烟株生长,显著提高烟叶活性氧和重金属含量。外源CBD对烟株生长存在低促高抑作用。当CBD浓度分别为1.0mg/L(Cd)和5.0mg/L(Cr)时效果最佳,显著降低了烟叶超氧阴离子(O₂^-·)产生速率,丙二醛、H₂O₂和烟株Cd、Cr含量;显著提高烟株干重、叶片超氧化物歧化酶、过氧化物酶、多酚氧化酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶活性,增加抗坏血酸(As A)、谷胱甘肽(GSH)含量以及As A/DHA(氧化型抗坏血酸)、GSH/GSSG(氧化型谷胱甘肽)。综上,适量CBD能有效缓解Cd和Cr胁迫对烟叶的氧化损伤,抑制烟株内重金属的积累,促进植株生长。