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1.
The effects of the interaction between sodium chloride, nitrate, and concentrations on growth and internal ion content of faba bean (Vicia faba L.) plants were studied, to understand the relationship between the above parameters and salt tolerance. Increased salinity substantially reduced the dry weight of roots and shoots and increased the root/shoot biomass ratio. Additional nitrate‐N considerably moderated the salinity effects on these parameters. The promotive effects of nitrate‐N were more pronounced on shoot dry weight. These results suggest that an exogenous supply of nitrate‐N would improve the vegetative growth of V. faba plants by moderating the suppresive effects of salinity. The evolution of the root and shoot content in potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), and nitrogen (N) was monitored during vegetative growth. A high correspondence between total N and Ca content was found. The acquisition of Ca and K in response to salt and nitrate was similar in shoots and roots, whereas Mg uptake showed notable differences in the two organs. In salt‐affected plants, the roots were found to be high in accumulated Na while the shoots exhibited the lowest Na concentration. Potassium accumulation was higher in the shoots. In this way, there was an antagonistic effect between Na and K uptake. Analyses of the nutrient contents in plant organs have provided a data base on salt‐tolerance mechanisms of V. faba plants.  相似文献   

2.
Two pairs of contrasting rice genotypes, each pair having similar general characteristics but differing in their tolerance to salt, were compared in short‐term experiments of NaCl absorption and translocation in intact plants. At low external NaCl concentration (0.1 mM), the absorption of Na was passive with a constant net influx rate (In), while the absorption of Cl was an active process obeying Michaelis‐Menten kinetics. At both low and high external NaCl concentrations (0.1 and 50 mM), salt‐tolerant ‘Pokkali’ had significantly lower rates of Na and Cl absorption than did salt‐sensitive ‘Peta’, although another moderately salt‐tolerant genotype, ‘IR 29725–25–22–3‐3–3’, did not differ from its salt‐sensitive counterpart, ‘IR 5’. For both pairs of the plants, translocation rates of Na and Cl were significantly lower in the salt‐tolerant genotypes than in the salt‐sensitive ones. It was concluded that exclusion of Na and/or Cl from the shoots may involve both absorption and translocation components of regulation. For relatively salt‐tolerant genotypes, a better regulation of either or both of the two components results in lower Na and/or Cl contents in the shoots, leading to a higher degree of salt tolerance.  相似文献   

3.
Ion relations, water content, leaf water potential, and osmotic adjustment were determined for cultivated barley (cv Harrington) and wild barley grown under mixed sulphate (SO4) salts with varied calcium (Ca) supply using a hydroponic system. Salinity induced significant increases of leaf, stem and root sodium (Na) concentrations in both species. Salt‐stressed wild barley roots accumulated more Na than shoots, and transport of Na from roots to shoots was low compared to Harrington. Cultivated barley had lower Ca concentrations than wild barley, especially in the low Ca salt treatment. Although potassium (K/Na) and Ca/Na ratios were higher in control wild barley plants than in Harrington, they declined under salt stress, irrespective of Ca supply. Major osmotica in wild barley leaves were K, sugars, organic acids, and quaternary ammonium compounds, while in Harrington they were cations, including Na, K and Mg, and anions such as phosphate (PO4) and SO4. Wild barley maintained better water status than Harrington under low Ca salt treatment. Supplemental Ca improved water status more in Harrington than in wild barley. Lack of osmotic adjustment to salinity in wild barley apparently resulted from its ion exclusion. Low Ca salt treatment caused Ca deficiency, Na toxicity, and loss of turgor in Harrington. In the high Ca salt treatment, Harrington had improved water and ion relations, as well as positive turgor.  相似文献   

4.
营养液栽培条件下,在成株期以 80 mmol/L NaCl 胁迫中国南瓜 360-3×112-2 F1和黑籽南瓜植株,10d 后,测定了植株的生长量和不同器官中Na+、K+、Ca2+、Mg2+的含量。结果表明,NaCl 胁迫下两种材料的生长受到明显抑制,360-3×112-2杂交种的生长抑制比黑籽南瓜植株较轻。NaCl 胁迫后两种南瓜植株体内Na+含量升高,360-3×112-2杂交种的Na+主要累积在根部,黑籽南瓜主要积累在茎中;K+、Ca2+、Mg2+的含量在植株体内呈下降的趋势,但360-3×112-2杂交种的上位叶中的含量却上升。NaCl胁迫下,因Na+的积累抑制了K+的吸收,植株各器官的K+/Na+普遍降低,但黑籽南瓜比360-3×112-2杂交种的K+/Na+下降明显。这些结果说明,两种南瓜受到盐胁迫后Na+的主要积累器官不同,致使地上部各器官有不同的K+、Ca2+、Mg2+吸收和积累特性,K+/Na+降低幅度也不同,从而影响了植株的生长,产生了耐盐性的差异。360-3×112-2杂交种耐盐性比黑籽南瓜强,可望作为耐盐砧木在瓜类生产上使用。  相似文献   

5.
Two pairs of contrasting rice genotypes, each pair having similar general characteristics but with marked differences in whole plant salt tolerance, were compared in terms of growth response and NaCl accumulation of whole plants as well as their corresponding callus cultures. At the whole plant level, salt‐tolerant genotypes ‘Pokkali’ and ‘IR 29725–25–22–3‐3–3’ outperformed their respective salt‐sensitive counterparts, ‘Peta’ and ‘IR 5’, as measured by such tolerance indices as damage index, relative biomass and relative fresh weight/dry weight ratio. The salt‐tolerant genotypes generally had lower Na and Cl contents in the shoots than did the salt‐sensitive genotypes, indicating that reduced Na and/or Cl accumulation in the shoots can be used as a physiological index of salt tolerance in rice. No significant differences, however, were found between the contrasting genotypes either in growth response or NaCl accumulation in callus cultures, suggesting that there is no direct relationship between salt tolerance at the cellular level and the whole plant level.  相似文献   

6.
Two creeping bentgrass clones having contrasting salinity tolerance collected from a salinity tolerant population were examined for growth responses and ion uptake under NaCl stressed conditions. The two clones showed differences in dry weight partitioning and morphological changes under salt stress. The clone with greater salt tolerance has greater ion partitioning differences in Na, Na/K and Cl levels between organ tissues.  相似文献   

7.
AZ‐Germ Salt II, a salt tolerant line of alfalfa (Medicago sativa L.) at the germination stage, was compared with its parent line Mesa Sirsa in sand culture at the germination and seedling stages and in hydroponic culture at the adult stage under greenhouse conditions. The sodium chloride (NaCl) treatments used were 0 or 100 mol/m3 in half strength Hoagland nutrient solution. AZ‐Germ Salt II was superior to Mesa Sirsa in biomass production at all three stages. AZ‐Germ Salt II had significantly greater chloride (Cl) in the plumules and radicle than Mesa Sirsa at the germination stage. The two lines did not differ in shoot and root sodium (Na) and shoot Cl at the seedling stage. However, at the adult stage AZ‐Germ Salt II accumulated significantly higher Na in the shoots and roots and Cl in the shoots compared with Mesa Sirsa. The two lines did not differ in tissue potassium/sodium (K/Na) ratios in all three experiments, although K concentrations were higher in the seedling shoots and roots, and in the plumules of AZ‐Germ Salt II than Mesa Sirsa. The K versus Na selectivities were higher in the plumules and seedling shoots and roots of AZ‐Germ Salt II compared with Mesa Sirsa, whereas at the adult stage the reverse was true. The lines also did not show any difference in tissue calcium (Ca) concentrations at any stage. It is concluded that salt tolerance in these two lines is not age‐dependent. The pattern of ion accumulation varies with the change in growth stage. Generally there is a positive correlation between Na and Cl accumulation and growth in alfalfa.  相似文献   

8.
向日葵芽苗期离子对复合盐胁迫的响应   总被引：4，自引：2，他引：4  
研究向日葵耐盐的离子响应机制,可为快速筛选耐盐向日葵品种提供科学依据。本试验以油用向日葵盐敏感品种‘YK18’、中度耐盐品种‘YK06’和耐盐品种‘GF01’为试验材料,研究0 mmol·L~(–1)、50 mmol·L~(–1)、100 mmol·L~(–1)、150 mmol·L~(–1)、200 mmol·L~(–1)和250 mmol·L~(–1)复合盐(NaCl和Na_2SO_4按9∶1摩尔比混合)浓度下的种子萌发和离子在萌发幼苗中积累分布情况,并利用离子流检测技术,动态监测了复合盐胁迫24 h后植株根系的K~+、Na~+、Ca~(2+)等离子的流速流向。结果表明,复合盐胁迫抑制向日葵种子萌发,导致发芽率下降,平均发芽时间延长。盐胁迫后向日葵根系K~+大量外排,流速为‘YK18’‘YK06’‘GF01’;随着盐胁迫浓度升高,根系Na~+流速由内吸转为外排,内吸时‘YK18’速度最大,‘YK06’次之,‘GF01’最小,外排时‘GF01’流速最大,其"排盐"现象明显。复合盐胁迫后,整株的Na~+积累量增加,K~+减少,K~+/Na~+随着盐浓度升高而下降;低盐浓度(150 mmol·L~(–1))下‘GF01’和‘YK06’茎秆中K~+/Na~+低于‘YK18’;高盐胁迫(≥150 mmol·L~(–1))下,‘GF01’整株Na~+积累最少,叶片K~+/Na~+最高。另外,盐胁迫下向日葵幼苗根系Ca~(2+)的吸收速率加快,‘GF01’是‘YK18’的2倍。由此可见,不同耐盐性的油用向日葵植株在盐胁迫下可通过调节Na~+、K~+和Ca~(2+)的吸收与外排来适应盐胁迫环境,耐盐性强的品种具有更强的保K~+能力,并通过区域化Na~+(低盐胁迫)和拒盐机制(高盐胁迫)来提高其对盐胁迫的耐受性,维持植株叶片中合理的K~+/Na~+值。本研究结果可为盐碱地耐盐品种筛选和栽培提供理论依据。  相似文献   

9.
盐胁迫下马蔺的生理反应研究   总被引：2，自引：0，他引：2  
Chinese iris （Iris lactea Pall. var. chinensis （Fisch） Koidz.）, a robust iridaceous plant, is widespread in arid and semiarid regions with high salinity. However, the mechanism of its salt tolerance is not well understood. In this study, plant growth, water status, content and distribution of inorganic ions, cell membrane permeability, and proline content of I. laetea under salt stress were investigated using nutrient solutions with six NaCl concentrations ranging from 0 to 350 mmol L^-1. The results indicated that the biomass, height, fresh weight, K^＋ content, and K^＋/Na^＋ and Ca^2＋/Na^＋ ratios decreased with increasing NaCl stress, whereas plant water deficit and contents of Na^＋ and Cl- increased with increasing NaCl stress. In all salt treatments, water deficit of shoots was found to be higher than that of roots and had a positive correlation with salt concentration. When the NaCl concentration was less than 280 mmol L^-1, the ion absorption selectivity ratio and the transportation selectivity ratio sharply increased with increasing NaCl stress. Under medium salt stress, I. lactea exhibited a strong K^＋ selective absorption and the transportation of K^＋ from roots to shoots increased, whereas Na^＋ was not transported and was mostly retained in roots. The plants were able to maintain osmotic adjustment through the accumulation of Na^＋, Cl-, and proline. On the basis of its biomass production under salt stress, I. lactea could be considered as a facultative halophyte.  相似文献   

10.
The effects on two‐week‐old plants of a salt‐tolerant line (Euroflor) and a salt‐sensitive (SMH‐24) line of sunflower, of varying sodium/calcium (Na/ Ca) ratios in a saline growth medium were assessed after three weeks growth in sand culture under greenhouse conditions. The different Na/Ca ratios of the salt treatment were 36.5, 74.0, and 149, at a constant concentration of 150 mol m‐3 NaCl. Euroflor was superior to SMH‐24 in fresh and dry matters of shoots and roots at varying external Na/Ca ratios. The leaf Na+ concentration in SMH‐24 increased consistently with increase in external Na/Ca ratio, whereas that in Euroflor remained almost unaffected. Although leaf chlorine (Cl‐) was significantly greater in SMH‐24 than Euroflor, there was no effect of decreasing Ca2+ concentration of the saline growth medium on the leaf Cl‐ concentrations of both lines. The lines did not differ in K+, Ca2+ or Mg2+ concentrations of both shoots and roots. The leaf K/Na and Ca/ Na ratios, K versus Na selectivity were considerably higher in Euroflor than in SMH‐24. The lines also did not differ in leaf water potential and gas exchange and these variables were not affected due to decreasing Ca2+ concentration of the saline growth medium. Stomatal conductance and transpiration remained unchanged in Euroflor, whereas those in SMH‐24 decreased significantly at the highest external Na/Ca ratio. Euroflor had significantly greater stomatal conductance and transpiration than those of SMH‐24 at almost all external Na/Ca ratios, whereas the reverse was true for water use efficiency. It was established that Euroflor was tolerant to low Ca2+ concentrations of the saline growth medium as compared with SMH‐24. This was mainly attributable to accumulation of relatively low Na+ and Cl‐ in the leaves, and maintenance of high leaf K/Na and Ca/Na ratios and K versus Na selectivity in Euroflor.  相似文献   

11.
Two lines of sunflower (Helianthrus annuus L.), a salt‐tolerant Euroflor and a salt‐sensitive SMH‐24, were grown for three weeks in sand culture containing 0 or 150 mol/m3 NaCl in full strength Hoagland nutrient solution. Distribution of cations in the leaves of varying ages was determined. The older leaves of SMH‐24 contained more sodium (Na) in the laminae than the younger leaves at the salt treatment, whereas laminae of leaves of varying ages of Euroflor maintained Na concentration almost uniform. Distribution of potassium (K), calcium (Ca), and magnesium (Mg) in the laminae was strongly age‐dependent in both lines, i.e., the older leaves contained greater concentrations of these cations than did the younger leaves. The lines did not differ in concentrations of the three cations. The older leaves of SMH‐24 had significantly lower K/Na ratios than those of Euroflor, but the lines did not differ in lamina Ca/Na ratios. It is concluded that distribution of K, Ca, and Mg in the leaf laminae is age‐dependent. Salt‐tolerance in sunflower is related to exclusion of Na in the leaf laminae and to maintenance of almost uniform concentrations of this ion in leaves of all ages.  相似文献   

12.
The effect of salinity on growth response, nitrogen (N) fixation and tissue mineral content was investigated for four legumes: faba bean (Vicia faba L), pea (Pisum sativum L), soybean (Glycine max L), and common bean (Phaseolus vulgaris L). Plants were grown in a vermiculite culture system supplied with a N‐free nutrient solution with the addition of 0, 50, and 100 mM NaCl. Plants were harvested at the beginning of the flowering period and the dry weights of shoots and roots and acetylene reduction activity (ARA) were evaluated at the same time plant tissues were analysed for N, potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) contents.

The depressive effect of saline stress on ARA of nodules was directely related to the salt induced decline in dry weight and N content in shoots. Growth inhibition by NaCl treatments was greater for the pea than for other legumes, whereas the soybean was the most salt‐tolerant Saline stress also affected the N content in shoots and roots. In general the N content accumulated in the shoot and Na in the roots of the four legumes tested, while K accumulated both organs. The acquisition of other macronutrients differed according to the legume species. The legumes most sensitive were P. sativum and V. faba which accumulated Ca in shoot and Mg both in the shoot and the roots. On the contrary, in G. max and P. vulgaris, the two most salt tolerant legumes, accumulated Mg in the roots and Ca in both vegetative organs. Our results suggest a relationship between the salt‐tolerant range in legumes and the macronutrient accumulation in vegetative organs.  相似文献   

13.
A greenhouse experiment was conducted to investigate the effect of exchangeable Na on the growth and absorption of metal elements in barley, rye, and maize. The plants were cultivated in soils whose exchangeable sodium percentages (ESP) were 6.6 (saline soil: Saline), 17.4 (saline-sodic soil: Sodic 1), and 39.6 (sodic soil: Sodic 2), which were prepared from Tottori sand dune soil (Control). The dry weight (DW) and concentrations of metal elements Ca, Mg, Mn, Zn, and Cu) in shoots were analyzed. The shoot DW was smaller with higher ESP, but in barley the difference between all the treatments was no longer observed with time. In Sodic soils, the growth of barley was vigorous, whereas rye growth was poor, and maize plants died by 5 weeks after planting. The Na concentration in shoots of all the species was higher with higher ESP. The K concentration in shoots was low at the early growth stage, but in barley it was higher in the Saline and both Sodic soils than in the Control at the subsequent stages. The concentrations of Ca and Mg in shoots of barley and maize in the Saline and both Sodic soils were higher than those in the Control, but in rye the concentrations were lowest in Sodic 2. The concentrations of Mn, Zn, and Cu in barley shoots in the Saline and bothSodic soils tended to be higher than those in the Control, whereas in rye they were lower than in the Control in both Sodic soils. Barley showed a higher ability to absorb low available microelements than rye and maize. These results indicate that barley is tolerant to sodicity as well as salinity, maize is tolerant to salinity, but is very sensitive to sodicity, and rye is moderately sensitive to both stresses. We suggest that the tolerance of grain crops to ESP involves a tolerance to a high Na concentration in shoots, the ability to keep suitable concentrations of essential cations in the presence of a high concentration of Na in shoots and the ability to absorb low available microelements.  相似文献   

14.
Ascorbate peroxidases （APX）, localized in the cytosol, peroxisome, mitochondria, and chloroplasts of plant cells, catalyze the reduction of H2O2 to water by using ascorbic acid as the specific electron donor. To determine the role of peroxisomal type ascorbate peroxidase （pAPX）, an antioxidant enzyme, in protection against salt-induced oxidative stress, transgenic Arabidopsis thaliana plant carrying a pAPX gene （HvAPX1） from barley （Hordeum vulgate L.） was analyzed. The transgenic line pAPX3 was found to be more tolerant to salt stress than the wild type. Irrespective of salt stress, there were no significant differences in Na^＋, K^＋, Ca^2＋, and Mg^2＋ contents and the ratio of K^＋ to Na^＋ between pAPX3 and the wild type. Clearly, the salt tolerance in pAPX3 was not due to the maintenance and reestablishment of cellular ion homeostasis. However, the degree of H2O2 and lipid peroxidation （measured as the levels of malondialdehyde） accumulation under salt stress was higher in the wild type than in pAPX3. The mechanism of salt tolerance in transgenic pAPX3 can thus be explained by reduction of oxidative stress injury. Under all conditions tested, activities of superoxide, glutathione reductase, and catalase were not significantly different between pAPX3 and the wild type. In contrast, the activity of APX was significantly higher in the transgenic plant than in wild type under salt stress. These results suggested that in higher plants, HvAPX1 played an important role in salt tolerance and was a candidate gene for developing salttolerant crop plants.  相似文献   

15.
ABSTRACT

Greenhouse experiments were conducted to assess the effects of salinization of soil on emergence, seedling growth, and mineral accumulation of Prosopis cineraria (Linn.) Druce (Mimosaceae). A mixture of chlorides and sulfates of sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) was added to the soil and salinity was maintained at 5.1, 7.2, 9.3, 11.5, and 13.3 dS m?1. A negative relationship between seedling emergence and salt concentration was obtained. Seedlings did not emerge when soil salinity exceeded 11.5 dS m?1. Results suggested that this tree species is salt tolerant at seed germination and seedling stages. Elongation of stem and root was retarded by increasing salt stress. Young roots and stem were most tolerant to salt stress, followed by old roots and leaves. Leaf tissue exhibited maximum reduction in dry-mass production in response to increasing salt stress. However, production of young roots and death of old roots were found to be continuous and plants apparently use this process as an avoidance mechanism to remove excess ions and delay onset of ion accumulation in this tissue. Plants accumulated Na in roots and were able to regulate transfer of Na ions to leaves. Stem tissues were a barrier for translocation of Na from root to leaf. Moreover, K decreased in root tissues with increased salinization. Nitrogen (N) content significantly (P < 0.01) decreased in all tissues (leaf, stem, and root) in response to low water treatment and salinization of soil. Phosphorus (P) content significantly (P < 0.01) decreased while Ca increased in leaves as soil salinity increased. Changes in elements-accumulation patterns and the possible mechanisms for avoidance of Na toxicity in tissues and organism level are discussed.  相似文献   

16.
水稻耐盐性的机理   总被引：15，自引：3，他引：15  
Shaheen Basmati was evolved as a salt tolerant fine rice variety by the Soil Salinity Research Institute,Pindi Bhattian, Pakistan. Water culture studies were conducted to investigate the physiological mechanism exercised by this variety in particular and rice plant in general to face the saline environment. Performance of this rice variety and the concentration and uptake of ions were studied under stress of three salinity levels(30, 60 and 90 mmolL^-1) created with NaC1. Recorded data indicated that shoot dry matter was not significantly affected by all the three levels of salinity. However, NaC1 levels of 60 and 90 mmol L^-1 affected the root dry matter significantly. Sodium concentration and uptake was enhanced significantly in root and shoot at the first level of salinity (30 mmol L^-1) but thereafter the differences were non-significant, indicating the preferential absorption of this cation. The K concentration decreased significantly in shoots at all the levels. The impact was less pronounced in roots as far as K absorption was concerned. The effect on Ca and Mg concentrations was not significant. The values of K:Na, Ca:Na and (Ca Mg):Na ratios in shoot and root were comparatively low under stress conditions, indicating that selective ion absorption may be the principal salt tolerance mechanism of variety Shaheen Basmati when grown in a saline medium.  相似文献   

17.
丛枝菌根对酸枣实生苗耐盐性的影响   总被引：15，自引：4，他引：15       下载免费PDF全文
本文研究了在土中加入不同量NaCl条件下 (0、1 5、3 0、4 5gkg-1干土 )接种丛枝菌根真菌 (AMF)Glomusmosseae对盆栽酸枣 (ZizyphusspinosusHu)实生苗生长及耐盐性的影响。结果表明 ,无论接种与否 ,植株的高度、根茎叶的干鲜重均随土壤NaCl浓度的增加而降低 ,而根、茎、叶和整株的Na浓度及Na全量均随土壤NaCl浓度的增加而增大。在土壤盐浓度相同的条件下 ,接种AMF植株的生长量 (株高、鲜重、干重等 )和叶片的叶绿素含量显著高于不接种植株。接种AMF的植株茎、叶中Na浓度低于不接种植株 ,而根中Na浓度、植株Na总量显著高于不接种植株。盐浓度最大的接种处理 ,其植株生长量和叶片叶绿素含量均高于不加盐不接菌处理。播种时进行盐胁迫处理和播种后 4 0d开始进行盐胁迫处理对菌根的侵染率、植株生长的影响差异不显著。上述四种盐浓度播种时进行盐处理的接种AMF植株的总干重比不接种植株分别提高 16 4 %、14 9%、4 8%、35 % ,在播种后 4 0d进行盐处理的接种AMF的植株比不接种植株分别提高 194 %、12 7%、72 %、4 6 %。结果证明 ,酸枣实生苗具有较强的耐盐性 ,其生长对菌根真菌有很强的依赖性 ,接种菌根真菌提高了其耐盐能力。  相似文献   

18.
Salinity tolerance in some plant species has been related to characteristics of potassium (K) and sodium (Na) uptake and transport. Tomato (Lycopersicon esculentum Mill., cv. Rossel) plants were grown in nutrient solution to determine effects of two K levels [0.2 (low) and 2 mmol (high)] combined with 0, 100, and 200 mmol NaCl on growth, and on Na and K uptake and translocation. Net uptake rates of Na and K were determined by disappearance in the growth medium and by plant accumulation. At the low level of K in solution, salinity decreased shoot and root dry weight and leaf area. Addition of 2 mmol K ameliorated of the added NaCl effects and improved growth parameters. Salinity reduced net K uptake rates and to a lesser extent K translocation from root to shoot, which resulted in higher K shoot concentration and a lower K root concentration. The inhibitory effect of salinity on K translocation was greater with low K level in nutrient solution. Net uptake of K was dependent on K level in the growth medium. Addition of K resulted in decreases of shoot Na uptake. The translocation of Na from roots to shoots was reduced by K level in nutrient solution. These results indicate that K supply and K accumulation and regulation in plant tissue contribute to salt tolerance and growth enhancement.  相似文献   

19.
不同品种油葵对盐胁迫响应研究   总被引：1，自引：0，他引：1  
通过盆栽试验,研究了盐胁迫对不同品种油葵出苗、生长、产量及植株Na+和K+吸收的影响,明确不同品种油葵对盐胁迫效应的差异。结果表明,随土壤盐浓度的升高,油葵的出苗率、株高、产量和生物量均有所下降,新葵杂6号受到的抑制作用更加明显;与全生育期的相比,各品种在出苗阶段的耐盐性远高于成苗至成熟期阶段,低盐胁迫对油葵的出苗和后期生长均有一定的促进作用。研究发现当盐胁迫对油葵苗期生长的相对抑制率超过40%时不能完成其生活史,超过50%时则不能生长至成熟期,在显蕾或花期枯死。随着盐胁迫程度的加剧植株中Na+的含量成倍增加,K+/Na+显著降低,而K+含量变化较小,适宜的盐浓度可促进植株对钾的吸收,但品种间存在较大的差异,在同一盐浓度下油葵植株中Na+含量陇葵杂1号<法A15<新葵杂6号,而K+含量与K+/Na+则刚好相反,各品种对盐胁迫的敏感性均为花期、显蕾期>苗期>成熟期;减少植株对Na+的吸收,维持K+的稳定性,保持较高K+/Na+是品种耐盐的重要机制之一,三个油葵品种中,陇葵杂1号耐盐性最强,其次为法A15,新葵杂6号耐盐性较差。  相似文献   

20.
The potassium/sodium (K/Na) ratio in the shoots of six rapid‐cycling Brassica species was greatly reduced by seawater salinity. It proportionally decreased with increasing salinity from 4 dS/m to 12 dS/m. This decrease was correlated with salt‐induced growth reduction (expressed as the percentage of control) within a species. The change in K/Na ratio with increasing salinity, however, was not correlated with K‐Na selectivity. The change in K/Na ratio at the callus level corresponded to that at the whole plant level. Both K/Na ratio and K‐Na selectivity were not found to be correlated with the relative salt tolerance of these Brassica species, indicating that the maintenance of a high K/Na ratio as a mechanism for salt tolerance in these Brassica species was not operative. These results also suggest that a high shoot K/Na ratio or K‐Na selectivity may not be reliable selection criteria for salinity resistance in some species.  相似文献   

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