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1.
The use of saline waters is an option for the irrigation of salt tolerant ornamentals as competition for high quality water increases. However, despite the importance of ornamental shrubs in Mediterranean areas, salt tolerance of such species has received little attention. The aims of our investigation were to quantify the growth response and any injury symptom of 12 widely cultivated ornamental shrubs to irrigation with saline water and to investigate any possible relation with the concentration of Na+ and Cl− in the plants. Species were irrigated with different salinities (10, 40, and 70 mM NaCl) for a 120-day period. At the end of salt treatment, plants were sampled and dry biomass recorded; the relative growth rate (RGR) was also calculated. Root and leaf samples from each species were used to evaluate Na+, K+ and Cl− concentrations. Growth rates were significantly reduced in Cotoneaster lacteus, Grevillea juniperina and Pyracantha ‘Harlequin’, which also showed the highest percentage of necrotic leaves. The increasing external NaCl lead to an increase of Na+ and Cl− in roots and leaves of the different species, although less Na+ was accumulated than Cl−: growth reduction well correlated with the concentration of Cl− and/or Na+ in the leaves. The most sensitive species (i.e. C. lacteus, G. juniperina and Pyracantha ‘Harlequin’) had high concentrations of Na+ and/or Cl− in their leaves and also showed a decrease in their leaf K+/Na+ ratios. Even though other species (i.e. Bougainvillea glabra, Ceanothus thyrsiflorus, Leptospermum scoparium, Leucophyllum frutescens and Ruttya fruticosa) demonstrated a high ion concentration in their leaves, they could be considered relatively salt tolerant as there was little growth reduction and few symptoms of injury in the leaves. In some other cases (i.e. Cestrum fasciculatum, Escallonia rubra and Viburnum lucidum) the observed tolerance was related to higher ion concentration in the roots compared to the leaves, probably indicative of a limited transport to the shoots. Only in Eugenia myrtifolia was the absence of symptoms associated with a limited Na+ and Cl− uptake from the rhizosphere.  相似文献   

2.
The application of gibberellic acid during flower bud induction significantly reduced flowering of ‘Black Diamond’ and ‘Black Gold’ Japanese plums. The response depended on the concentration applied and on the type of shoot. Mixed shoots had a similar response in both varieties, flowering being reduced by 40% for GA3 50 mg l−1 and by 75–90% for GA3 75 mg l−1 or higher concentration. With regard to spurs, GA3 50 mg l−1 reduced flowering intensity by 40% and 25% in ‘Black Gold’ and ‘Black Diamond’, respectively, and GA3 75 mg l−1 or higher concentration reduced flowering by 70% and 50%, respectively. This partial inhibition of flowering significantly reduced the cost of manual thinning. The best GA3 concentration was found to be 50 mg l−1, since it reduced the cost of thinning by 45–47% and increased final fruit weight by 7–33% for ‘Black Diamond’ and ‘Black Gold’, respectively. Not significant differences in yield and in mature fruit characteristics of treated trees were found compared to untreated trees.  相似文献   

3.
Olive (Olea europaea L.) is the major fruit tree in the Mediterranean region, often grown in locations where plants are exposed to increased salinity. To determine the effect of NaCl on shoot and root growth, dry matter allocation, leaf Na+ and K+ concentration, electrolyte (EL) and K+ leakage (KL), seven olive cultivars of different origins were grown in nutrient solution containing 0, 33, 66, 100 or 166 mM NaCl for three months. The general effect of salinity was linear and quadratic decrease of observed plant growth parameters. Different responses of tested cultivars to applied levels of salinity were found for stem dry weight, shoot length and number of leaves. As salinity increased, growth of ‘Manzanillo’ declined sharply, whereas ‘Frantoio’ was the most tolerant to growth reduction in most of the observed growth parameters. Allometric analysis showed that biomass allocation under salinity stress was similar in all cultivars, but the slope between shoot weight and total plant weight decreased as salinity increased. Since the higher allocation in roots was not found, it seems that salinity only slowed the above ground plant canopy growth. Sodium concentration in leaves of all cultivars increased as salinity increased with the highest increment reached when the salinity of nutrient solution was raised from 100 to 166 mM NaCl. Significant differences among genotypes were found in leaf Na+ and K+ concentration and K+:Na+ ratio, but they were not related to the growth rate. Generally, ‘Frantoio’ and ‘Oblica’ accumulated less Na+ and were able to maintain higher K+:Na+ ratios as compared to other genotypes. Electrolyte leakage and KL linearly increased with increasing salinity and the magnitude of the response depended upon the olive cultivar.  相似文献   

4.
Salinity is one of the major environmental factors limiting crop productivity. The effect of increasing salinity levels (0, 50, 100 mM NaCl) on growth, photosynthetic traits, leaf water potential, oxidative stress, enzymatic and non-enzymatic antioxidants was studied in Pusa Jai Kisan and SS2 cultivars of mustard (Brassica juncea L. Czern & Coss.) differing in ATP-sulfurylase activity at 30 days after sowing (DAS). The cultivar SS2 (low ATP-sulfurylase activity) accumulated higher content of Na+ and Cl− in leaf than root. SS2 also showed greater content of thiobarbituric acid reactive substances (TBARS) and H2O2 and higher decrease in growth, photosynthetic traits and leaf water potential than Pusa Jai Kisan with increasing salinity levels. Contrarily, Pusa Jai Kisan (high ATP-sulfurylase activity) exhibited higher Na+ and Cl− content in root than leaf, lower TBARS and H2O2 content and higher activity of catalase, ascorbate peroxidase and glutathione reductase. However, the activity of superoxide dismutase was greater in SS2 than Pusa Jai Kisan. Higher activity of ATP-sulfurylase in Pusa Jai Kisan resulted in increased content of glutathione, a reduced form of inorganic sulfur and an essential component of cellular antioxidant defense system. The lesser decrease in growth and photosynthesis in Pusa Jai Kisan was the result of lesser Na+ and Cl− in leaf, higher turgidity and increased activity of antioxidant enzymes and glutathione content.  相似文献   

5.
SUMMARY

Response to increased salinity was compared in whole plants and calli from leaf, stem and root of Lycopersicon esculentum Mill. cv. P-73, Lycopersicon pennellii (Correll) D'Arcy ac PE-47 and their interspecific hybrid. Three NaCl treatments were applied (0, 70 and 140 raM) for 28 d. In both calli and whole plants, L. pennellii was more salt-tolerant than the cultivated species and the hybrid according to the growth responses, although different degrees of salt tolerance were generally found between plants and calli. The Na+ and CI" accumulations with salinity were higher in L. pennellii than in L. esculentum at both levels oforganization. The interspecific hybrid showed an accumulation ability for Na+ and CI" intermediate to its parents in the shoot of the whole plants and similar to L. pennellii in the callus tissues. Either no decrease or a small decrease of K+ concentrations with salinity were found in both whole plants and callus tissues of L. esculentum. However, K+ concentrations decreased in the organs and calli of L. pennellii and the hybrid with increasing salinity. Only at the whole plant level did L. pennellii have a Na7K+ ratio higher than L. esculentum, showing the hybrid to have values between those of its parents in the shoot.  相似文献   

6.
The effect of rootstock (‘MaxMa 14’, ‘Weiroot 13’, ‘PiKu 1’, ‘Weiroot 158’, ‘Gisela 5’ and ‘F12/1’) on phenolic acid and flavonol content of “Lapins” sweet cherry was investigated. Phenolic acids and flavonols were isolated from sweet cherries and analyzed by using reversed phase high-performance liquid chromatography (RP-HPLC). The major phenolic acids in sweet cherries were neochlorogenic acid (18–50 mg kg−1), chlorogenic acid (19–62 mg kg−1) and p-coumaric acid derivatives (15–125 mg kg−1). The amount of flavonol quercetin-3-rutinoside (8–37 mg kg−1) was significant as well. There are significant variations in the phenolic compound content among sweet cherry fruits grown on trees grafted on different vegetative rootstocks. The significantly higher chlorogenic acid, neochlorogenic acid, p-coumaric derivative and quercetin-3-rutinoside contents were found in sweet cherry fruits grown on trees grafted on ‘Weiroot 13’ and ‘PiKu 1’ rootstocks. Sweet cherries produced on trees grafted on other rootstocks had significantly lower phenolic compound content.  相似文献   

7.
Plant production under salinity requires increased capacity for K+ homeostasis. For this purpose, supplementary K2SO4 in the nutrient solution and grafting on a tolerant rootstock were employed in two experiments to test whether grafting, potassium and their interactions can alleviate salinity stress in tomato (Solanum lycopersicum L.). In Exp-ion, plants were cultivated for 122 days to compare different ionic compositions: EC 9 dS m−1 in ECall (by macro-nutrients) and in ECNaCl (by 64.2 mM NaCl), EC 12 dS m−1 in ECK (ECNaCl + 25.8 mM K+). Exp-K+ was established to compare K+ concentrations of 6, 16 and 36 mM at 150 mM NaCl. In both Experiments, ‘ZS-5’, selected as a salt sensitive cultivar, was either self-grafted or grafted onto the cultivar ‘Edkawi’, reported as salt tolerant. Yield and growth, minerals, gas exchange, soluble sugars, and proline were analyzed. Different ionic treatments affected almost all characteristics considered while differences between rootstocks were rarely observed. No pronounced differences were found in shoot growth, yield and gas exchange between ECall and ECNaCl. ECK did not show any salinity alleviative effects but inhibited even growth compared with the other treatments. In Exp-K+, 16 mM K+ increased plant growth, leaf soluble sugars and proline concentrations. 36 mM K+ did not further reduce upper leaf Na+ although leaf K+ concentration increased significantly. The results indicated that the response of tomato plant to NaCl stress was principally attributed to the osmotic component in Exp-ion, excessive K+ showed no mitigating effect on fruit yield and shoot growth. However, 16 mM K+ in the root environment enhanced the salt adaptive capacity of plants stressed at 150 mM NaCl. The use of the tolerant rootstock resulted in no ameliorative effects, owing to its susceptibility to blossom-end rot, failure in enhancing photosynthesis, and ineffectiveness of restraining the long-distance transport of Na+.  相似文献   

8.
South African Proteaceae are adapted to the low soil phosphorus (P) concentrations of the Cape Floristic Region. The efficient P uptake by Proteaceae means that these plants experience phosphorus (P) toxicity at lower rhizosphere [P] than crop plants. This is only problematic when cultivating Proteaceae (and many plants from this region) on previously agricultural land with high residual soil [P]. In this study we hypothesize that P toxicity will result in element imbalances in leaves of Proteaceae and information from this study aims to facilitate ameliorative treatments. Phosphorus toxicity was induced on-farm in Leucadendron ‘Safari Sunset’ (Proteaceae) with subsequent mapping of element distribution in non-necrotic leaf tissue using micro particle-induced X-ray emission spectrometry. Phosphate supply up to 0.01 mM in a fertigation solution resulted in increased stem length of Leucadendron ‘Safari Sunset’ while P concentrations in excess of this resulted in decreased stem length, increased leaf [P] up to 0.25% (w/w) and, between 1 mM and 5 mM P supply, typical P toxicity symptoms were observed. High P supply (5 mM P) resulted in increased leaf [P] in most leaf tissues including the epidermis, where calculations from an equilibrium speciation model indicated that there was 30% more dissolved PO43− in the epidermis compared to leaves at low P supply (0 mM added P on soil with 34 mg P kg−1). Concomitantly, bundle sheath and epidermal [Ca] were reduced and 10% more Ca was predicted to be adsorbed and precipitated as hydrapatite at high P supply. High P supply resulted in increased leaf [Cl] and [Mn] in all tissues studied; decreased total leaf [Fe], bundle sheath, xylem, phloem and epidermal [Fe] and decreased total leaf [Zn] and xylem and phloem [Zn]. The observed symptoms of P toxicity in Leucadendron ‘Safari Sunset’ (necrosis in some plants, chlorosis and leaf rosetting) co-occurred with (1) excess PO43−, which may bind Ca in the epidermis (leading eventually to necrosis); (2) reduced [Fe] and increased [Mn] (leading to chlorosis) and (3) reduced total and vascular [Zn] (leading to leaf rosetting).  相似文献   

9.
‘Orri’, a selection of ‘Orha’ mandarin [Temple (Citrus temple hort. ex Y. Tanaka) × Dancy (Citrus tangerina hort. ex Tanaka)], is a new high-quality Israeli mandarin which, in the last decade, has become one of the leading varieties in Israel. ‘Orri’ has an excellent taste, the rind is deep orange in color and easily removed, and it contains few or no seeds. However, ‘Orri’ grown in Israel suffers from inadequate yield and no published studies have yet addressed this problem. In the present study we determined that ‘Orri’ productivity depended on conditions being favorable to cross-pollination. Under cross-pollination conditions a positive correlation (R2 = 0.97) was found between yield per tree and number of fruits per tree, and more than 90% of the fruits exceeded 60 mm: the most profitable size range. These data suggest that the number of fruits per tree, and not fruit size, is the limiting factor for yield improvement in ‘Orri’ orchards. Studying seed set showed that ‘Michal’ mandarin (Citrus reticulata Blanco) is a compatible pollenizer for ‘Orri’ flowers: the number of seeds per ‘Orri’ fruit increased as the distance from ‘Michal’ trees decreased. The present study demonstrated that cross-pollination of ‘Orri’ resulted in yield improvement, yet at the price of increased seed set.  相似文献   

10.
Two separate experiments were conducted to evaluate the effectiveness of growth retardants in controlling height of oriental lily ‘Mona Lisa’. In first experiment flurprimidol was applied as a single foliar spray (0, 10, 20, 30 and 40 mg l−1) or a soil drench (0, 0.1125, 0.225, 0.3375 and 0.45 mg/pot) at two plant growth stages (7 and 15 cm). In second experiment flurprimidol (0, 10, 20, 30 and 40 mg l−1) and daminozide (0, 2500, 3500 and 4500 mg l−1) were applied once or twice as a foliar spray. Daminozide applied once or twice at concentrations of 2500–4500 mg l−1 was ineffective in ‘Mona Lisa’ growth retardation. Flurprimidol was effective growth retardant in reducing stem extension without adverse side-effects. The maximum reduction in plant height obtained was 45% compared to controls. Flowering time was not affected by lower rates of flurprimidol, but it was slightly delayed when retardant was applied at higher doses. The tepal size, leaf size and pedicel length were smaller than those of the control plants. Intensified leaf colour was observed on flurprimidol treated ‘Mona Lisa’. The effect of flurprimidol persisted in the year after treatment.  相似文献   

11.
Changes caused by NaCl-induced salinity on several growth parameters and ions accumulation have been measured in five olive (Olea europaea L.) cultivars (‘Chemlali’, ‘Chetoui’, ‘Koroneiki’, ‘Arbequina I18’, and ‘Arbosana I43’) growing in a greenhouse in nutrient solution pot experiment. One-year-old plants were transplanted to sand–perlite (1:1) culture, and were irrigated with half-strength Hoagland nutrient solution containing NaCl at various levels (0.5, 50, 100 and 200 mM). Salinity induced significant decrease in growth parameters, but to a different extent in each cultivar. Leaf growth and total leaf area per plant were significantly affected by all salinity treatments in all studied cultivars, being ‘Arbequina I18’ the most sensitive cultivar. Leaf drop phenomenon was observed from 60 days after salt application at high salinity treatments, mainly in Arbequina I18. Contrary to leaf area, leaf thickness increased progressively during the experiment. ‘Chemlali’ developed thicker leaves at the two highest salinity treatments when compared to the other cultivars. Na+ and Cl− concentrations were higher in roots than in shoots and leaves in most of the cultivars investigated. The effectiveness of Na+ exclusion mechanism in the roots differed significantly among studied cultivars, working effectively in ‘Chemlali’ (by inhibiting translocation of Na+ to the aerial part) and being much less efficient in ‘Arbequina I18’. Furthermore, leaf abscission can be considered as an additional tolerance mechanism of olive cultivars allowing the elimination of leaves that had accumulated Na+ and Cl− ions. Tolerance to salinity stress was as follows: ‘Chemlali’ > ‘Chetoui’ > ‘Arbosana I43’ > ‘Koroneiki’ > ‘Arbequina I18’. This order of salt tolerance was indicated by lower reduction in plant growth parameters (shoot elongation, trunk diameter, total plant dry weight, internodes length, and total leaf area), the increase of leaf thickness, and by the effectiveness of the exclusion mechanism of Na+ and Cl− in the root system.  相似文献   

12.
Effects of arbuscular mycorrhizal fungi (AMF) alone or in combination with bacterial consortium (AMF+BC) inoculation prior to induced salinity (NaCl @ 150 or 250 mM) were studied on root growth; plant biomass; leaf area; Na+ and K+ contents; leaf water potential (Ψw); osmotic potential (Ψπ); photosynthesis rate (Pn); and contents of chlorophyll, phytohormones, and polyamines in the grape rootstock ‘Dogridge’, popular among Indian vine growers. AMF inoculation in the NaCl untreated rootstocks plants increased root growth, root and shoot biomass, and leaf area and improved leaf Ψw, Ψπ, Pn, and chlorophyll content, and also countered the stress-induced decline in the NaCl treated plants. The abscisic acid (ABA), cytokinins, and polyamine-spermidine and spermine contents in the leaves of NaCl untreated or treated were significantly increased by the AMF inoculation. Among the treatments, AMF with BC was relatively more effective than AMF alone with respect to changes in above morpho-physiological characters. The results depicted that AMF (AMF alone or AMF+BC) inoculation significantly improved salinity tolerance of grape rootstock and tolerance is induced by improvements in plant water balance, K+:Na+ ratio, and Pn, besides distinct accumulations in ABA and polyamines-spermine and spermidine. The above findings have potential in suggesting the AMF usefulness in improving the efficacy of ‘Dogridge’ rootstock in grape cultivation under salt affected soils.  相似文献   

13.
Two eggplant cultivars, Dilnasheen and Bemisal, were selected to assess whether pure GB and sugarbeet extract could effectively ameliorate the harmful effects of salt stress on eggplant (Solanum melongena L.), under saline conditions. Salt stress markedly suppressed the growth, yield, photosynthetic capacity, internal CO2 level, transpiration, and stomatal conductance in both cultivars. Potassium (K+) and Ca2+ contents and K+/Na+ ratios of both root and leaf were also reduced, while GB and proline in leaves, and Na+ and Cl− contents in roots and leaves were significantly enhanced. Exogenously applied glycinebetaine and sugarbeet extracts significantly counteracted the salt-induced adverse effects on growth, yield, various gas exchange characteristics, GB and leaf K+, Ca+, Cl− and Na+. However, GB and sugarbeet extract showed differential effects on photosynthetic rate, stomatal conductance and transpiration, internal CO2 level, Ci/Ca ratio, leaf K+, Ca2+, and Cl− contents, and K+/Na+ ratio. Sugarbeet extract proved better than the GB in improving growth, photosynthetic rate, transpiration, stomatal conductance, yield and GB accumulation. Since, sugarbeet extract contains a substantial amount of GB along with a variety of other important nutrients so it was found as effective as pure GB in improving growth and some key physiological processes in eggplant under salt stress. Thus, it can be used as an alternative cheaper source of GB for its use as an ameliorative agent for protecting plants against the hazardous effects of salt stress.  相似文献   

14.
In this study, seedlings of tomato were treated with salt stress or alkali stress. The growth, photosynthesis and concentrations of solutes and inorganic ions in tissue sap of stressed seedlings were measured to investigate the physiological adaptive mechanisms by which tomato tolerates alkali stress. The alkali stress clearly inhibited growth and photosynthesis. With increasing salinity, the Na+ concentration and Na+/K+ ratio in leaves increased, with greater degrees of increase under alkali than under salt stress. This indicated that high-pH caused by alkali stress might affect the control of roots on Na+ uptake and increased the intracellular Na+ to a toxic level, which might be the main cause of reductions of stomatal conductance and net photosynthetic rates under alkali stress. Under salt stress, organic acids (OAs), Na+, K+ and Cl− were the main osmolytes in both roots and leaves. Under alkali stress, roots and leaves revealed different mechanisms of ion balance and osmotic regulation. Under alkali stress, in roots, OAs and Na+ were the main osmolytes, and the osmotic role of K+ was small; however, in leaves, OAs, Na+ and K+ all played important osmotic roles. The mechanisms governing ionic balance under both stresses were different. Under salt stress, the contribution of inorganic ions to keep ion balance was greater than that of OAs. However, under alkali stress, Cl−, H2PO4− and SO42− concentrations decreased, and tomato might have enhanced OA synthesis to compensate for the shortage of inorganic anions.  相似文献   

15.
The aim of this study was to evaluate the effects of low molecular mass antioxidants and NaCl salinity on growth, ionic balance, proline, and water contents of ‘Zard’ olive trees under controlled greenhouse conditions. The experiment was carried out by spraying 2 mM of ascorbic acid (Asc) and 3 mM of reduced glutathione (GSH) on the plants that were treated with two salinity levels (0 and 100 mM NaCl) on their root medium. Plant growth parameters (leaf fresh weight, leaf dry weight, leaf number, total fresh weight, and total dry weight) were significantly improved by Asc compared with growth parameters in GSH and control plants. Higher concentrations of Na+ and Cl– were observed in salt-stressed plants, while Na+ and Cl– concentrations were decreased in the olive leaves that were sprayed with Asc. Salinity in the root zone caused a considerable decline in both K+ concentration and K/Na ratio. K+ concentration and K/Na ratio were significantly increased by application of Asc on plant leaves. Salinity caused an increase in electrolyte leakage (EL) compared with the control plants. Lowest EL and tissue water content (TWC) was obtained in Asc-sprayed plants, whereas TWC was increased in salt-stressed plants. Plants were subjected to salt stress and showed a higher relative water content (RWC) than the control plants. Salt stress induced proline accumulation in olive leaves. In conclusion, exogenous application of Asc is recommended to improve tolerance of olive plants under saline conditions.  相似文献   

16.
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17.
《Scientia Horticulturae》2005,103(3):289-303
In a 2-year field study, strawberry cvs. ‘Elsanta’ and ‘Korona’ were exposed to three different levels of NaCl salinity supplied as aqueous solutions characterised by electrical conductivities of 0.3 dS/m, 2.6 dS/m, and 5.1 dS/m. Salinity in the rhizosphere reduced plant growth by up to 44% in ‘Korona’ and 90% in ‘Elsanta’. A rather distinct cultivar difference represented the reduction in leaf area per plant of 85% in the second year of experiment in ‘Elsanta’ compared to 29% in ‘Korona’. Strawberry can be regarded as a Na+ excluder, because Na+ content of both strawberry cultivars remained below 3 mg g−1 dry mass at all salinity levels. Cl− content increased considerably, up to 70 mg g−1 dry mass in ‘Korona’ and 80 mg g−1 dry mass in ‘Elsanta’ plants. ‘Korona’ retained most of its Cl− in roots and crowns, whereas in ‘Elsanta’ the maximum was detected in petioles. ‘Korona’ was able to accumulate up to 33% higher Cl− content in the roots than ‘Elsanta’. Macronutrient deficiency due to NaCl salinity was not observed and in comparison to ‘Elsanta’, higher Cl− content in roots of ‘Korona’ did not coincide with an impairment of macronutrient uptake. Salinity stress reduced fruit yield by up to 27% in ‘Korona’ and 64% in ‘Elsanta’. Fruit quality, characterised as taste, aroma, and texture by a consumer-type panel, decreased by more than 24% in ‘Elsanta’, but in ‘Korona’ differences were insignificant. Total soluble solids (Brix) and the ratio Brix/TA (TA, titratable acid) decreased significantly by about 20% in ‘Korona’ and 35% in ‘Elsanta’. To summarise, the ability of ‘Korona’ to retain Cl− in the root system more effectively than ‘Elsanta’ resulted not only in a 41% lower leaf Cl− content at the highest salinity level and a better growth under NaCl stress, but also in a relatively higher fruit yield and fruit quality.  相似文献   

18.
In this study, we investigated the effects of 10 mM CaCl2 on membrane permeability, malondialdehyde (MDA), reactive oxygen species (ROS), and Na+, K+, Ca2+, and Mg2+ concentrations in different organs of sour jujube grown under 150 mM NaCl stress. Our results showed 73% leaf wilting in the Na treatment. The Na treatment significantly increased leaf superoxide (O2.?) production rates, hydrogen peroxide (H2O2) concentrations, cell membrane permeability, MDA concentrations, and Na+ concentrations in roots, stems, and leaves. The Na treatment significantly reduced K+, Ca2+,and Mg2+ concentrations in roots, but increased K+ concentrations in stems. Compared with the Na treatment, 39% of the leaves showed wilting symptoms in the Na+Ca treatment. The Na+Ca treatment significantly decreased leaf O2.? production rates, H2O2 concentrations, cell membrane permeability, and MDA concentrations. Moreover, the Na+Ca treatment (1) significantly reduced Na+ concentrations in roots, stems, and leaves; (2) significantly increased root K+ concentrations; (3) significantly increased K+/Na+ ratios in roots; (4) significantly increased Ca2+ concentrations in stems and leaves, and Mg2+ concentrations in roots. In conclusion, exogenous CaCl2 reduces NaCl stress in sour jujube by reducing Na+ concentrations and increasing K+, Ca2+, and Mg2+ concentrations in various plant organs.  相似文献   

19.
The effects of NaCl stress on plant growth, gas-exchange, activity of superoxide dismutase (SOD), rate of lipid peroxidation, and accumulation of Na+ ion and sugar were investigated in leaves and fruits of pepper plants (Capsicum annuum L.). Especially, the gene expression of l-galactono-1,4-lactone dehydrogenase (GalLDH), which is the last enzyme of ascorbic acid (AsA) biosynthesis, and the relationships between AsA level and Na+ concentration in plant tissue were investigated with increasing salinity. Plants were treated with three treatments: the control (0 mM NaCl) and two salinity levels (50 and 100 mM NaCl) for 21 days under greenhouse conditions. Plant growth was markedly restricted due to the reduction of photosynthetic rate and the increase of Na+ accumulation in leaves with the increasing intensity of NaCl stress. Salinity had more effect on fruit growth comparing to leaf growth, suggesting that fruits could be more sensitive to salinity than leaves. In comparison with the control, salt stress significantly increased lipid peroxidation (as measured as malondialdehyde content) but decreased SOD activity in both fruits and leaves although the effect was larger in fruits; and the rate of the decrease in SOD activity was greater than that of the increase in lipid peroxidation. The AsA concentration transiently increased first 7 days but it slightly decreased from the initial level in the end of treatment day 21. The change in GalLDH gene expression was similar to AsA concentration. The accumulation of Na+, the reduction of AsA level at severe salinity stress were greater in fruits than in leaves; and AsA level had a negative relationship with Na+ concentration in both leaves and fruits. These results suggest that the difference in salt sensitivity between fruits and leaves in pepper plants can be related to the difference in inhibition of AsA synthesis, which in turn is probably due to the toxicity of extreme accumulation of Na+.  相似文献   

20.
The effects of two types of hydrophilic polymers on drought and salt resistance of 1-year-old cuttings of Populus popularis 35–44 were investigated in this study. The polymers used in the experiments were Stockosorb 500 XL (Stockosorb) (a granular type, cross-linked poly potassium-co-(acrylic resin polymer)-co-polyacrylamide hydrogel) and Luquasorb® product (a powder type of potassium polyacrylate), which were manufactured by Stockhausen GmbH Krefeld and BASF Corporation in Germany, respectively. Drought or salt stress significantly decreased leaf photosynthesis and transpiration, as well as plant water-consumption and dry weight. A significant reduction occurred in Drought + NaCl-stressed plants. Soils treated by 0.5% Stockosorb or Luquasorb markedly alleviated the inhibition of plant growth and leaf gas-exchange that were caused by drought and/or salt stress treatments, and the occurrence of stress-induced leaf injury was delayed for 31 and 51 days, respectively. Experimental results showed that hydrophilic polymers in root media assisted P. popularis plants to tolerate the drought and salt stresses, due to the following reasons: (1) roots took up the retained water from hydrophilic polymers when water was deficient in the soil (Stockosorb-treated plants exhibited a higher rate of water uptake); (2) under saline conditions, Stockosorb and Luquasorb held Na+ and Cl− in the soil solution due to their high water-holding capacity, thus limiting an excessive accumulation of toxic ions in the plant organs; furthermore, the exchangeable K+ that contained in Stockosorb and Luquasorb resulted in an improved K+/Na+ homeostasis in salinized plants; (3) hydrophilic polymers aided the plants to tolerate an interactive impacts of drought and salt stresses, which was mainly accounted for their water- and salt-holding capacities. In comparison, the growth and survival enhancement effects of the hydrophilic polymers on Drought + NaCl-treated plants was more evident by Luquasorb application, because it supplied water to plants at a lower rate during soil drying, thus prolonging the duration of water supply and allowed roots to grow in an environment of lower salinity for a long period of salt and drought stresses.  相似文献   

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