Calcium increases sodium exclusion in olive plants

‘Picual’ olive cuttings were grown in a greenhouse under saline conditions in 2 L plastic pots containing perlite. Plants were irrigated with a nutrient solution plus 75 mM NaCl and 0, 2.5, 10 or 40 mM CaCl₂. Vegetative growth, leaf and root Na⁺ and Ca²⁺ concentrations were measured. Na⁺ toxicity symptoms were observed in plants non-treated with Ca²⁺. Shoot length was higher in Ca²⁺ treated plants, although shoot growth was reduced at 40 mM CaCl₂, probably due to the high total ion concentration reached in the external solution. Ca²⁺ supply linearly increased leaf and root Ca²⁺ concentration and decreased leaf Na⁺ concentration. However, there were no differences in root Na⁺ concentration. Results indicate Ca²⁺ may take part in the Na⁺ exclusion mechanism, mainly preventing Na⁺ transport to the shoot, that may be an important ability for survival under saline conditions.     

Plant water stress and K starvation reduce absorption of foliar applied K by olive leaves

Three-month-old mist-rooted ‘Picual’ olive cuttings were transplanted into 2-l plastics pots containing perlite as substrate and fertigated with a complete nutrient solution containing 0.05, 0.1 or 2.5 mM KCl depending on the experiment. In the first experiment, plants were sprayed with RbCl (Rb⁺ is a K⁺ analog) at a rate of 4% at 63 days after transplanting (DAT). Foliar Rb⁺ uptake through leaves increased with K⁺ concentration in the nutrient solution, indicating that foliar Rb⁺ uptake was lower when plants were K⁺ deficient than when they were adequate. On the contrary, it was observed that translocation of Rb⁺ from leaves to other organs of the plant was higher under K⁺ deficiency conditions. In the second and third experiments, when differences appeared on shoot length due to K⁺ nutritional status (0.05 or 2.5 mM KCl) at 63 DAT, a group of plants were subjected to water stress during 7 weeks. On the other hand, another group of plants (control plants) did not receive any water stress treatment during the experiments. After this period of 7 weeks, all plants were sprayed with RbCl at 4%. Leaf K⁺ concentration diminished in water-stressed plants independently of plants nutritional status. Foliar Rb⁺ uptake through leaves was restricted by water stress either in plants with low K⁺ (0.05 mM KCl) or plants with high K⁺ (2.5 mM KCl). Translocation of Rb⁺ from leaves was greater under water stress conditions in both K⁺ nutritional statuses. In conclusion, the results obtained could explain the irregular response in olive trees to foliar K⁺ sprays, particularly, when they grow in rainfed orchards.     

Polyamine analysis in salt stressed plants of olive (Olea europaea L.)

A rapid and sensitive method to analyse polyamines in olive (Olea europaea L.) tissues was developed, using thin-layer chromatography and densitometry. Putrescine (Put), spermidine (Spd) and spermine (Spn) were detected at very low tissue concentrations. The involvement of polyamines during salt stress was assessed by supplying one year old olive plants (cvs Leccino and Carolea) with different NaCl concentrations in sand culture. Control plants always contained more Put than Spd and Spn. Salt induced the accumulation of Spd and Spn. Furthermore a dramatic decrease in root Put content was observed in plants supplied with increasing NaCl concentrations (50-150 mM). These results differ from those of previous experiments on polyamine accumulation induced by other stresses, indicating a need to optimize sampling procedures.     

Ameliorative effects of biological treatments on growth of squash plants under salt stress

The objective of this work was to evaluate the effect of selected biologicals on direct seeded and transplanted squash plant growth and mineral content under salinity stress. The study was conducted in pot experiments using a mixture of sandy loam soil:vermiculite (1:1, v:v) under controlled greenhouse conditions. Biologicals tested included AgBlend, SoilBuilder, Yield Shield, PlantShield, Inoculaid and Equity. Salinity treatments were established by adding 0, 50 and 100 mM of NaCl to a base complete nutrient solution (Hydro-Sol + Ca(NO₃)₂). Pots were irrigated with NaCl solutions and biological treatments were included in the water. Yield Shield was applied as a seed treatment. Salinity negatively affected growth of squash; however, biological treatments significantly increased fresh weight compared to non-treated plants that were challenged with salt stress. Furthermore, biological treatments tested increased the uptake of potassium compared to the non-treated control in both direct seeded and transplanted squash. Sodium concentration was not affected by biologicals in directed seeded squash except for SoilBuilder, Yield Shield and Equity at 100 mM, while AgBlend, SoilBuilder, Inoculaid and Equity decreased sodium uptake in transplants under salt stress. The most effective biologicals increased the K⁺/Na⁺ ratio, which was positively correlated with plant growth. Alteration of mineral uptake may be one mechanism for the alleviation of salt stress. Based on the results of the experiment reported herein, the use of biological treatments may provide a means of facilitating plant growth under salt stress.     

盐胁迫对黄瓜不同耐盐品种植株K~+和Na~+含量的影响

用体积浓度225mmol/L的NaCl对耐盐性不同的2个黄瓜品种进行处理,研究黄瓜盛果期NaCl胁迫下不同品种叶片和根中K+和Na+含量的变化。结果表明,盐胁迫下,黄瓜不同耐盐品种植株根和叶片中Na+含量明显增加,K+含量明显下降;耐盐品种叶片中Na+含量显著低于盐敏感品种,耐盐品种K+含量降低幅度显著小于盐敏感品种;植株的Na+、K+比值提高,耐盐品种Na+、K+比值显著低于盐敏感品种;耐盐品种SNa+,K+显著低于盐敏感品种。     

Zinc influence and salt stress on photosynthesis,water relations,and carbonic anhydrase activity in pistachio

A greenhouse study was conducted to evaluate the ameliorative effects of zinc (0, 5, 10 and 20 mg Zn kg⁻¹ soil) under saline (800, 1600, 2400 and 3200 mg NaCl kg⁻¹ soil) conditions on pistachio (Pistacia vera L. cv. Badami) seedlings’ photosynthetic parameters, carbonic anhydrase activity, protein and chlorophyll contents, and water relations. Zn deficiency resulted in a reduction of net photosynthetic rate and stomatal conductance. The quantum yield of photosystem II was reduced at zinc deficiency and salt stress. Zinc improved plant growth under salt-affected soil conditions. Increasing salinity in soil under Zn-deficient conditions, generally decreased carbonic anhydrase activity, protein, chlorophyll a and b contents. However, these adverse effects of salinity alleviated by increasing Zn levels up to 10 mg kg⁻¹ soil. Under increasing salinity, chlorophyll a/b ratio significantly increased. Zinc treatment influenced the relationship between relative water content and stomatal conductance, and between leaf water potential and stomatal conductance. It concluded that Zn may act as a scavenger of ROS for mitigating the injury on biomembranes under salt stress. Adequate Zn also prevents uptake and accumulation of Na in shoot, by increasing membrane integrity of root cells.     

The effect of waste water irrigation on the extra virgin olive oil quality from the Tunisian cultivar Chemlali

The availability of fresh water is very scarce in the Middle East and North Africa. Yet consequently, brackish water or recycled wastewater can be used for irrigation, minimising the exploitation of natural water resources. The aim of this work was to study how irrigation with treated wastewater (TWW) over 4 years affects some parameters of “Chemlali” olive oil quality. Two treatments were considered: trees irrigated with treated wastewater and others cultivated in rain-fed conditions. Results showed that irrigation with TWW over 4 years did not affect free acidity, and specific ultraviolet absorbance at K₂₃₂ and K₂₇₀. For both the crop seasons the mean values of these parameters were lower than the upper limits established for “extra virgin” olive oil. However, irrigation with TWW cumulatively increased palmitic, palmitoleic, linoleic and linolenic acid contents and decreased oleic acid rates. A significant decrease of total phenol contents was also observed at the end of experimental period.     

苹果幼苗部分根系水分胁迫对光合作用主要参数的影响

以1年生苹果组培苗为试材,用改良的Hoagland营养液加20%PEG-6000进行半根渗透胁迫(HS)处理,与仅加营养液的正常水分条件的对照(CK)和加20%PEG-6000进行全根胁迫处理(TS)进行比较,研究了根系不均匀供水条件下植株的叶片水势和光合作用主要参数的反应特点。结果表明,HS与CK之间叶片的日出前水势不存在显著差异,且显著高于TS,但日水势变化动态在大部分情况下HS显著低于CK;和CK相比较,HS处理的叶片气孔导度、蒸腾速率和净光合效率显著降低,但在处理的早期显著高于TS。HS还导致叶片温度较对照显著增高。另外,试验体系中HS处理部分根系处于水分胁迫状态,而另外的根系处于良好的水分供应条件下,可用于模拟定位灌溉和分根区交替灌溉根系不均匀供水条件,对于开展相关果树生理反应及生长发育调控机制的研究提供了良好的试验体系。     

The effect of micro-organisms on susceptibility to freezing-damage in petals of cut rose flowers

The susceptibility of cut rose flowers to freezing-damage at sub-zero temperatures was examined. A correlation was found between visible freezing-damage and electrolytic conductance of petal leachate; electrolytic conductance was therefore used to evaluate the extent of freezing-damage.Inoculation of flowers with microbial suspension rendered them more susceptible to freezing-damage. The antibiotic streptomycin reduced the susceptibility to freezing-damage of flowers inoculated with micro-organisms, but did not affect the susceptibility of freshly-cut, untreated flowers.The significance of these findings is discussed in relation to temperature management during storage of cut flowers. It is suggested that freezing-damage is influenced by the presence of bacteria which proliferate during later phases of flower development and act as ice nuclei in the flower.     

Impacts of water stress on gas exchange,water relations,chlorophyll content and leaf structure in the two main Tunisian olive (Olea europaea L.) cultivars

Leaf structural adaptations for the reduction of water loss were examined in two olive (Olea europaea L.) cultivars (Chemlali and Chétoui) growing under water stress conditions. Leaf measurements included leaf tissue thickness, stomatal density, trichome density, specific leaf area, leaf density, water relations, and gas exchange. We found considerable genotypic differences between the two cultivars. Chemlali exhibited more tolerance to water stress, with a thicker palisade parenchyma, and a higher stomatal and trichome density. Chemlali leaves also revealed lower specific leaf area and had higher density of foliar tissue and lower reduction in net CO₂ assimilation rate. The mechanisms employed by these two cultivars to cope with water deficit are discussed at the morpho-structural level. The morphological and structural characteristics of the leaves are in accordance with physiological observations and contribute to the interpretation of why the olive cv. Chemlali is more drought-tolerant than cv. Chetoui. Furthermore, from the behaviour of Chemlali plants we consider this cultivar very promising for cultivation in semi-arid areas.     

Moderating water stress in tomato (Lycopersicon esculentum Mill.) plants by application of specific nitrogen doses

Summary

The effect of different doses of nitrogen on water stress in tomato (Lycopersicon esculentum Mill. ‘Royesta’) plants grown in a sandy soil and exposed, or not, to long-term water stress was studied. Nitrogen dose treatments consisted of Hoagland’s solution (N1 treatment), Hoagland’s solution + 40 mM NO₃^– (N2 treatment), or Hoagland’s solution + 80 mM NO₃^– (N3 treatment) applied every 3 d, for a total of seven applications following plant establishment. Subsequently, daily application of 80% (stressed) or 100% (unstressed) of the water evapotranspired by control plants the previous day was combined, factorially, with the three nitrogen treatments, for a period of 2 weeks. The leaf fresh weight (FW) at full turgor:leaf dry weight (DW) ratio was high in plants under the N1 and N3 stress treatments, with no significant difference between them soon after the start and at the end of the water stress treatment. However, the N2 treatment produced a significant increase in the ratio in well-watered plants, but not in water-stressed plants at the end of the stress period. The surface area per leaf was greater in stressed than in control plants, except for N2. Leaf water potential was greatly reduced in stressed N2 and N3 plants, but was unaltered in their well-watered counterparts. The significant increases in relative water content at the turgor loss point (around 3%) and in cell membrane rigidity (an increase of more than 125% in the bulk modulus of elasticity) clearly indicate an osmotic adjustment in stressed N2 plants, confirming that this N dose moderated the effects of the water stress imposed on N2 plants.     

Regulated deficit irrigation in potted Dianthus plants: Effects of severe and moderate water stress on growth and physiological responses

The purpose of this study was to analyze the physiological and morphological response of carnation plants to different levels of irrigation and to evaluate regulated deficit irrigation as a possible technique for saving water through the application of controlled drought stress. Carnations, Dianthus caryophyllus L. cultivar, were pot-grown in an unheated greenhouse and submitted to two experiments. In the first experiment, the plants were exposed to three irrigation treatments: (control); 70% of the control (moderate deficit irrigation, MDI) and 35% of the control (severe deficit irrigation, SDI). In the second experiment, the plants were submitted to a control treatment, deficit irrigation (DI, 50% of the control) and regulated deficit irrigation (RDI). After 15 weeks, MDI plants showed a slightly reduced total dry weight, plant height and leaf area, while SDI had clearly reduced all the plant size parameters. RDI plants had similar leaf area and total dry weight to the control treatment during the blooming phase. MDI did not affect the number of flowers and no great differences in the colour parameters were observed. RDI plants had higher flower dry weight, while plant quality was affected by the SDI (lower number of shoots and flowers, lower relative chlorophyll content). Leaf osmotic potential decreased with deficit irrigation, but more markedly in SDI, which induced higher values of leaf pressure. Stomatal conductance (g_s) decreased in drought conditions more than the photosynthetic rate (P_n). Osmotic adjustment of 0.3 MPa accompanied by decreases in elasticity in response to drought resulted in turgor less at lower leaf water potentials and prevented turgor loss during drought periods.     

Effects of water and salt stresses on growth,water relations and gas exchange in Rosmarinus officinalis

Summary

Plants of Rosmarinus officinalis were submitted to water and salt stress, independently. The effects of water or salt stress on growth, water relations and gas exchange were investigated in order to understand the tolerance and adaptative mechanisms of R. officinalis to these types of stress. Under both stress conditions, plants developed avoidance mechanisms to minimise water loss based on morphological and physiological changes (e.g., reduction of plant biomass and leaf area, stomatal closure). Only under salt stress conditions were treated plants able to maintain turgor via osmotic adjustment, which was achieved by the uptake of Na⁺ and Cl^– ions. Osmotic adjustment was not observed in R. officinalis plants submitted to water stress. The results indicate that high accumulation of Na⁺ and Cl^– ions was responsible for the growth reduction observed in salinised plants. However, the growth reduction observed in water-stressed plants was caused by a dehydration process.     

Hydro-priming increases seed germination and early seedling growth in two cultivars of Napa cabbage (Brassica rapa subsp. pekinensis) grown under salt stress

To assess the effects of hydro-priming on enhancing germination and seedling growth in Napa cabbage (Brassica rapa subsp. pekinensis) under salt stress, seeds of two Napa cabbage cultivars that differed in salt tolerance, ‘Lainong 50’ (salt-tolerant) and ‘Xiaoza-56’ (salt-sensitive), were soaked in distilled water at 20°C in the dark for 10 h. Hydro-primed and non-primed seeds were then germinated under six levels of salinity (0, 50, 100, 150, 200, or 250 mM NaCl) under laboratory conditions. Various germination traits (e.g., germination percentages, germination potential, and seedling vigour index), anti-oxidant enzyme [catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD)] activities, and proline and malondialdehyde (MDA) concentrations were then measured in 7-d-old seedlings. The results showed that salt-stress decreased seed germination traits and reduced early seedling growth in both Napa cabbage cultivars. Hydro-priming increased the seed germination percentages and early seedling growth in both cultivars grown under salt stress. These effects were significantly positively correlated with the activities of POD and CAT, and the accumulation of proline, which can alleviate oxidative membrane damage and result in decreased MDA concentrations. These findings suggest that hydro-priming is an effective method to increase seed germination percentages, germination potential, and early seedling growth in Napa cabbage grown under salt stress.     

A new approach to varietal identification in plants by microsatellite high resolution melting analysis: application to the verification of grapevine and olive cultivars

Background  

Microsatellites are popular molecular markers in many plant species due to their stable and highly polymorphic nature. A number of analysis methods have been described but analyses of these markers are typically performed on cumbersome polyacrylamide gels or more conveniently by capillary electrophoresis on automated sequencers. However post-PCR handling steps are still required. High resolution melting can now combine detailed sequence analysis with the closed-tube benefits of real-time PCR and is described here as a novel way to verify the identity of plant varieties such as grapevine and olive.     

Effects of water deficit on olive trees cv. Chemlali under field conditions in arid region in Tunisia

Water scarcity in the Mediterranean basin in addition to the extension of irrigated lands is one of the main factors limiting agricultural development. The need for supplementary irrigation of the Chemlali olive cultivar (Olea europaea L.) during summer and autumn periods was investigated. Leaf water content, gas exchange parameters, fruit development and yield in rain-fed and in irrigated plants have been monitored in 12-year-old olive trees grown under environmental conditions in semi arid regions characterized by high temperatures and high light intensity. Trees were subjected to three irrigation treatments, T0, T1 and T2 corresponding respectively to 0, 33 and 66% of crop evapotranspiration (ET_c) by a drip irrigation system. The water deficit during the summer (from June to August) led to the decrease of soil moisture, leaf water content and gas exchange parameters. Irrigated trees showed the same slow activity in the three summer months as the rain-fed trees. For all treatments, net CO₂ assimilation, stomatal conductance and transpiration rates were markedly decreased by environmental conditions (high air temperature and high light intensity) during the summer period. At the partial active growth phase of the Chemlali olive cultivar (September–November), a significant re-increase in all parameters was observed. However, net photosynthesis and stomatal conductance of control plants (T0) were, respectively, 57 and 40% lower than those of plants conducted under milder water contribution (T1). The decrease of physiological activity in irrigated plants during hot and dry (summer time) and cold (winter) seasons was a clear evidence that water supply during such periods will be without a great benefit for photosynthetic activity, and thus growth, if applied under critical conditions inducing the rest phase of the plant. The non-statistically significant slight differences as well in photosynthetic performances activities (Pn, Gs and E rates), as in olive production between the two irrigated treatments will not cover the expenses of water loss when applying irrigation at 66% of ET_c especially in arid region characterized by scant and irregular rainfall. On the light of these results, we can conclude that the irrigation of this species during the vegetative growth phase (in spring and autumn), and stopping it during the olive rest phase (in summer and winter) could be recommended at least under the experimental conditions of this study; and that the contribution of 600 mm of water per year (33% of ET_c) can respond to the needs of the Chemlali olive cultivar in a semi arid region without impairing photosynthetic activity and olive production.     

外源脱落酸对大庆地区盐胁迫下甜瓜幼苗生理指标的影响

通过模拟大庆地区土壤盐胁迫环境,研究了不同浓度脱落酸对该环境下甜瓜幼苗生理指标的影响。结果表明,盐胁迫下甜瓜幼苗叶绿素a、b含量以及a/b值、脯氨酸含量、可溶性糖含量、根系活力降低,丙二醛含量升高;盐胁迫下,加入外源脱落酸可调节甜瓜幼苗的生长,1×10~(-7)mol·L~(-1)和1×10~(-6)mol·L~(-1)脱落酸处理能改善甜瓜各种生理指标,而高浓度外源脱落酸则增加了胁迫伤害程度。说明一定浓度范围的外源脱落酸能提高甜瓜耐盐性,缓解了大庆土壤盐胁迫环境对甜瓜幼苗的伤害。     

The effect of water deficit stress on the growth,yield and composition of essential oils of parsley

Three parsley cultivars (plain-leafed, curly-leafed and turnip-rooted) were grown under conditions of 35–40% and 45–60% water deficit in order to evaluate the effect of this form of stress on plant growth, essential oil yield and composition. Plant growth (foliage and root weight, leaf number) was significantly reduced by water stress, even at 30–45% deficit. Water stress increased the yield of essential oil (on a fresh weight basis) from the leaves of plain-leafed and curly-leafed, but not turnip-rooted, parsley. However, on a m² basis foliage oil yield increased significantly only in curly-leafed parsley. Water stress also caused changes in the relative contribution of certain aroma constituents of the essential oils (principally 1,3,8-p-menthatriene, myristicin, terpinolene + p-cymenene), but these changes varied between cultivars. The oil yield of roots was low and water deficit stress had relatively little effect on the root oil composition. It is concluded that because the biomass of plants subjected to water deficit is reduced, it is possible to increase the plant density of plain-leafed or curly-leafed parsley, thereby further increasing the yield of oil per m². However, the application of water deficit stress to parsley essential oil production must also take into account likely changes in oil composition, which in turn relate to the cultivar.     

Combination of taurine and diazepam has neuroprotective effect on focal cerebral ischemia-reperfusion in rats

AIM: To observe the neuroprotective effect of combined treatment with taurine and diazepam against focal cerebral ischemia-reperfusion in rats. METHODS: Sixty male Sprague-Dawley rats were randomly divided into five groups: sham-operation group, vehicle group, taurine group (200 mg/kg, ip), diazepam group (10 mg/kg, ip) and combined treatment group (taurine 100 mg/kg+diazepam 5 mg/kg). Focal cerebral ischemia was induced by the method of middle cerebral artery occlusion (MCAO) in rats, and reperfusion was emerged by removing the thread 2 h later. The drugs were administered respectively at the time of reperfusion, and subsequently repeated once 12 h later. The animals in vehicle group were intraperitoneally injected with isodose normal saline. The neurological deficit score, the brain water content and cerebral infarction were measured 48 h after MCAO. Other 5 group animals of focal cerebral ischemia-reperfusion (n=16 in each group) were set up as mentioned above and accepted treatments 10 h after reperfusion, likewise repeated once 12 h later. Twelve animals in each group were adopted the same management as the previous 5 groups at 48 h after MCAO. The remained 4 animals in each group were sacrificed until two weeks after MCAO to observe the histopathological changes by nissl staining. RESULTS: Compared to vehicle group, the animals in combined treatment group at 2 h or 12 h after MCAO both decreased the neurological deficit score, reduced the brain water content and infarct volume (P<0.01 or P<0.05). The combined treatment significantly alleviated the neurological necrosis as well. The neuroprotective effect of the combined treatment was superior to that of using taurine or diazepam alone. CONCLUSION: These results suggest that combination of taurine and diazepam treatment has a coordinate neuroprotective effect on both the acute and chronic brain damage of focal cerebral ischemia-reperfusion.