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1.
微咸水滴灌条件下不同盐分离子在土壤中的分布特征   总被引：7，自引：9，他引：7  
开展田间试验研究微咸水滴灌条件下不同盐分离子在土壤中的分布特征。试验采用5个水平的微咸水灌溉处理：电导率分别为1.1 dS/m(K1)，2.2 dS/m(K2)，2.9 dS/m(K3)，3.5 dS/m(K4)和4.2 dS/m(K5)，重复3次，按随机区组布置。试验结果表明：滴灌条件下各种盐分离子的迁移速度与分布特性不同，Ca2+、Mg2+与SO2-4易于被灌溉水分淋洗，主要分布在湿润体外围，而HCO-3、Na+与Cl-主要分布在湿润体内部。生育期内土壤剖面上的平均盐分含量没有增加，但对土壤结构与作物有重要影响，Cl-、Na+、HCO-3有增加的趋势。  相似文献   

2.
Water samples from 18 springs and 13 drainage canals and subcanals were collected from Al-Ahsa Oasis. Concentrations of total dissolved salts, Cl, SO4 HCO3, B, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, V, Ti, and Zn were determined. The soil salinity development (SSD), the adjusted Na ratio (adj. SAR), the adjusted Na adsorption ratio (adj. RNa), and exchangeable Na percentage (ESP) were calculated. Sodium was the most abundant cation in all water samples followed by Ca, Mg, Sr, and K in descending order. Concentrations of all other metals were below 0.1 mg L–1. Chloride was the most abundant anion, followed by SO4 and HCO3 in these waters. A significant correlation (P < 0.05)=" between=" na=" and=" cl=" in=" water=" samples=" was=" found.=" thermodynamic=" calculations=" revealed=" that=" an=" appreciable=" fraction=" of=" ca=" and=" mg=" in=" spring=" and=" drainage=" waters=" were=" associated=" with=">4 and HCO3 ions. Calcium increased from less than 10 meq L–1 in spring waters to > 16 meq L–1, Mg was doubled, and Na and Cl increased several times in the drainage waters. The salinity and sodicity hazards of the spring and drainage waters were classified as C4S2 i.e. high salinity with medium sodicity problems.  相似文献   

3.
A greenhouse experiment was conducted to determine the effect of salinity on the efficacy of two arbuscular mycorrhizal fungi (AMF), Glomus mossea and natural mycorrhiza, of Glomus species, was investigated in terms of growth and nutrition of corn plant (Zea mays L). Plants were grown under different salinity levels imposed by 2.0, 2.5, 3.5, 5.0, 8.0, 12.0 dS m?1of Hoagland's Solution [sodium chloride (NaCl), sodium sulfate (Na2SO4), Calcium dichloride (CaCl2), and magnesium sulfate (MgSO4) 7:9:3:1 ratio, respectively]. Both types of mycorrhizal fungi did not display significant protection in the host plant against the detrimental effects of the soil salinity. The effect of inoculation on growth varied only with the level of salinity. Maximum root colonization and spore numbers were observed in plants cultivated with low salinity levels. It was found that significant interaction between AMF x Salinity level for calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) of shoot, and for Zn and Mn, of root.  相似文献   

4.
The aim of this study was to determine the salt tolerance of pepper (Capsicum annuum L.) under greenhouse conditions and to examine the interactive effects of salinity and nitrogen (N) fertilizer levels on yield. The present study shows the effects of optimal and suboptimal N fertilizer levels (270 kg ha?1 and 135 kg ha?1) in combination with five different irrigation waters of varying electrical conductivity (EC) (ECiw = 0.25, 1.0, 1.5, 2.0, 4.0, and 6.0 dS m?1) and three replicates per treatment. At optimal N level, yield decreased when the irrigation water salinity was above ECiw 2 dS m?1. At the suboptimal N level, a significant decrease in yield occurred only above ECiw 4 dS m?1. At high salinity levels the salinity stress was dominant with respect to yield and response was similar for both N levels. Based on the results it can also be concluded that under saline conditions (higher than threshold salinity for a given crop) there is a lesser need for N fertilization relative to the optimal levels established in the absence of other significant stresses.  相似文献   

5.
Groundwater contaminated with sulfate (SO4 2‐) at concentrations higher than allowable for drinking water might still be usable for irrigation. Objectives were to determine the growth response and mineral uptake of two forage crops irrigated with waters containing SO4 2‐ at concentrations ranging from 175 to 1743 mg/L, and with electrical conductivities (EC) ranging from 1.2 to 3.6 dS/m. Plants were grown for 12 weeks in 8‐L pots containing a calcareous sandy loam and were harvested at 4, 8, or 12 weeks for plant growth measurements and tissue analysis. Digested leaves, stems, and reproductive tissues were analyzed by inductively coupled plasma (ICP) spectroscopy at each harvest, as were saturated soil paste extracts. Shoot growth of tall fescue (Festuca arundinacea Schreb.) was not affected by irrigation water treatment, whereas shoot growth of alfalfa (Medicago sativa L.) was increased by a moderate level of soil solution SO4 2‐ Sulfur (S), boron (B), magnesium (Mg), sodium (Na), and zinc (Zn) concentrations in shoot tissues of both species showed a tendency to increase with increasing SO4 2‐ content of irrigation water. Shoot tissue concentration of molybdenum (Mo) increased with maturation in both species, while the concentrations of B, potassium (K), manganese (Mn), Na, and Zn decreased. Soil saturated paste extract concentrations of Mg and Na increased with irrigation water Mg and Na concentrations, while Ca and S concentrations in the soil solution became saturated at the higher irrigation water concentrations of these elements.  相似文献   

6.
《Journal of plant nutrition》2013,36(12):2689-2704
ABSTRACT

Salinity is among the most widespread and prevalent problems in irrigated agriculture. Many members of the family Chenopodiaceae are classified as salt tolerant. One member of this family, which is of increasing interest, is quinoa (Chenopodium quinoa Willd.) which is able to grow on poorer soils. Salinity sensitivity studies of quinoa were conducted in the greenhouse on the cultivar, “Andean Hybrid” to determine if quinoa had useful mechanisms for salt tolerant studies. For salt treatment we used a salinity composition that would occur in a typical soil in the San Joaquin Valley of California using drainage waters for irrigation. Salinity treatments (ECi ) ranging from 3, 7, 11, to 19?dS?m?1 were achieved by adding MgSO4, Na2SO4, NaCl, and CaCl2 to the base nutrient solution. These salts were added incrementally over a four-day period to avoid osmotic shock to the seedlings. The base nutrient solution without added salt served as the non-saline control solution (3?dS?m?1). Solution pH was uncontrolled and ranged from 7.7 to 8.0. For comparative purposes, we also examined Yecora Rojo, a semi-dwarf wheat, Triticum aestivum L. With respect to salinity effects on growth in quinoa, we found no significant reduction in plant height or fresh weight until the electrical conductivity exceeded 11?dS?m?1. The growth was characteristic of a halophyte with a significant increase in leaf area at 11?dS?m?1 as compared with 3?dS?m?1 controls. As to wheat, plant fresh and dry weight, canopy height, and leaf area did not differ between controls (3?dS?m?1) and plants grown at 7?dS?m?1. Beyond this threshold, however, plant growth declined. While both quinoa and wheat exhibited increasing Na+ accumulation with increasing salinity levels, the percentage increase was greater in wheat. Examination of ion ratios indicated that K+:Na+ ratio decreased with increasing salinity in both species. The decrease was more dramatic in wheat. A similar observation was also made with respect to the Ca2+:Na+ ratios. However, a difference between the two species was found with respect to changes in the level of K+ in the plant. In quinoa, leaf K+ levels measured at 19?dS?m?1 had decreased by only 7% compared with controls. Stem K+ levels were not significantly affected. In wheat, shoot K+ levels had decreased by almost 40% at 19?dS?m?1. Correlated with these findings, we measured no change in the K+:Na+ selectivity with increasing salinity in quinoa leaves and only a small increase in stems. In wheat however, K+:Na+ selectivity at 3?dS?m?1 was much higher than in quinoa and decreased significantly across the four salinity levels tested. A similar situation was also noted with Ca2+:Na+ selectivity. We concluded that the greater salt tolerance found in quinoa relative to wheat may be due to a variety of mechanisms.  相似文献   

7.
The deposition of magnesium (Mg)‐rich dust from magnesite mining activities has resulted in serious land degradation. However, the main factors limiting plant growth in Mg‐contaminated soils are unclear. Moreover, little information is available on the remediation of Mg‐contaminated soils. In this study, remediation of soils contaminated with Mg‐rich dust was investigated in a pot experiment using maize as the indicator plant. There were five treatments: (i) control; (ii) leaching; (iii) application of CaCl2; (iv) leaching + CaCl2 application; and (v) application of Ca(H2PO4)2 · H2O. Soil properties and growth of maize (Zea mays L.) seedlings were measured. Leaching alone significantly decreased soluble Mg concentration. Leaching + CaCl2 application greatly increased exchangeable Ca concentration and decreased soil pH by 0·3 units. Application of CaCl2 alone increased soluble Mg concentration sharply, which directly inhibited the germination of maize seeds. Application of Ca(H2PO4)2 · H2O significantly increased the concentrations of exchangeable Ca and available phosphorus and decreased soil pH by 1·7 units. The biomass of maize seedlings increased in the order of control = leaching < leaching + CaCl2 < < Ca(H2PO4)2 · H2O. These results suggested that the plant growth in Mg‐contaminated soils was limited primarily by Ca deficiency and secondarily by high soil pH when exchangeable Ca was sufficient. High soil pH suppressed plant growth probably mainly by inhibiting phosphate uptake from the soil. Applying acid Ca salt with low solubility is an attractive option for the remediation of Mg‐contaminated soils. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
The antioxidative protection system as adaptation strategy to high soil salinity in the leaves of two tomato (Lycopersicon esculentum Mill.) hybrids (Buran F1 and Berberana F1) was investigated. Changes in the activity of superoxide‐dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), as well as total and oxidized ascorbate concentrations (AA and DHA) in the plant leaves subjected to three salinity levels (EC 3.80 dS m−1, 6.95 dS m−1, and 9.12 dS m−1) relative to non‐saline control were analyzed during the fruiting phase. The obtained results clearly indicate a relation between SOD activity and AA concentration in the antioxidative protection without any peroxidase‐related H2O2 detoxification. Increased SOD activity accompanied by high AA concentration was noticed at all salinity levels, but the response of hybrids was specific for the particular salt concentration. The first salinity level (EC 3.80 dS m−1) induced the highest level of AA in the Buran F1 (70%), while in Berberana F1 hybrid leaves the highest AA concentration (64%) was noticed at the third salinity level (9.12 dS m−1). All salinity levels caused a decline in POD and APX activities in both hybrids. The possibility of a predominant role of ascorbate and SOD in the antioxidative protection of mature tomato leaves under long‐term salt stress is discussed.  相似文献   

9.
Salt-affected soils are widespread, particularly in arid climates, but information on nutrient dynamics and carbon dioxide (CO2) efflux from salt-affected soils is scarce. Four laboratory incubation experiments were conducted with three soils. To determine the influence of calcium carbonate (CaCO3) on respiration in saline and non-saline soils, a loamy sand (6.3% clay) was left unamended or amended with NaCl to obtain an electrical conductivity (EC) of 1.0 dS?m?1 in a 1:5 soil/water extract. Powdered CaCO3 at rates of 0%, 0.5%, 1.0%, 2.5%, 5.0% and 10.0% (w/w) and 0.25-2 mm mature wheat residue at 0% and 2% (w/w) were then added. Cumulative CO2-C emission from the salt amended and unamended soils was not affected by CaCO3 addition. To investigate the effect of EC on microbial activity, soil respiration was measured after amending a sandy loam (18.8% clay) and a silt loam (22.5% clay) with varying amount of NaCl to obtain an EC1:5 of 1.0–8.0 dS?m?1 and 2.5 g glucose C?kg?1 soil. Soil respiration was reduced by more than 50% at EC1:5?≥?5.0 dS?m?1. In a further experiment, salinity up to an EC1:5 of 5.0 dS?m?1 was developed in the silt loam with NaCl or CaCl2. No differences in respiration at a given EC were obtained between the two salts, indicating that Na and Ca did not differ in toxicity to microbial activity. The effect of different addition rates (0.25–2.0%) of mature wheat residue on the response of respiration to salinity was investigated by adding NaCl to the silt loam to obtain an EC1:5 of 2.0 and 4.0 dS?m?1. The clearest difference between salinity levels was with 2% residue rate. At a given salinity level, the modelled decomposition constant ‘k’ increased with increasing residue addition rate up to 1% and then remained constant. Particulate organic carbon left after decomposition from the added wheat residues was negatively correlated with cumulative respiration but positively correlated with EC. Inorganic N (NH 4 + -N and NO 3 ? -N) and resin P significantly decreased with increasing salinity. Resin P was significantly decreased by addition of CaCl2 and CaCO3.  相似文献   

10.
A laboratory incubation experiment was conducted to evaluate the effect of magnesium chloride–induced salinity on carbon dioxide (CO2) evolution and nitrogen (N) mineralization in a silty loam nonsaline alkaline soil. Magnesium chloride (MgCl2) salinity was induced at 0, 4, 8, 12, 16, 20, 30, and 40.0 dS m?1 and measured CO2 evolution and N mineralization during 30 days of incubation. Both CO2 evolution and N mineralization decreased significantly with increasing salinity. The cumulative CO2 evolution decreased from 235 mg kg?1 soil at electrical conductivity (EC) 0.65 dS m?1 to 11.9 mg kg?1 soil at 40 dS m?1 during 30 days of incubation. Similarly, N mineralization decreased from 185.4 mg kg?1 at EC 0.65 dS m?1 to 34.45 mg kg?1 at EC 40.0 dS m?1 during the same period. These results suggested that increasing magnesium chloride salinity from 4 dS m?1 adversely affect microbial activity in terms of carbon dioxide evolution and N mineralization.  相似文献   

11.
Element mass balance estimates for South Carolina Coastal Plain watersheds indicate that fertilizers and liming materials are the major sources for inputs of Ca, Mg, K, Cl, and HCO3 whereas precipitation is the major input for Na and SO4. Stream flow is the chief mode of output for all of these elements. A balance between input and output is evident only for Cl. Retentions of 50% or more are shown by Ca, Mg, K, HCO3 and SO4 whereas Na shows an apparent net loss. The retention of Ca, Mg and HCO3 suggests that less than 25% of the dolomitic liming materials applied to the landscape actually dissolve and that the carbonate chemistry of Lower Coastal Plain streams is therefore probably largely controlled by seepage of groundwaters from underlying calcareous aquifers. The retention of K and the loss of Na may be due to cation exchange reactions on soil clays whereas the apparent retention of SO4 is probably due to reduction to H2S in floodplain environments and soil adsorption.  相似文献   

12.
The Nandong Underground River System (NURS) is located in Southeast Yunnan Province, China. Groundwater in NURS plays a critical role in socio-economical development of the region. However, with the rapid increase of population in recent years, groundwater quality has degraded greatly. In this study, the analysis of 36 groundwater samples collected from springs in both rain and dry seasons shows significant spatial disparities and slight seasonal variations of major element concentrations in the groundwater. In addition, results from factor analysis indicate that NO 3 ? , Cl?, SO 4 2? , Na+, K+, and EC in the groundwater are mainly from the sources related to human activities while Ca2+, Mg2+, HCO 3 ? , and pH are primarily controlled by water–rock interactions in karst system with Ca2+ and HCO 3 ? somewhat from anthropogenic inputs. With the increased anthropogenic contaminations, the groundwater chemistry changes widely from Ca-HCO3 or Ca (Mg)-HCO3 type to Ca-Cl (+NO3) or Ca (Mg)-Cl (+NO3), and Ca-Cl (+NO3+SO4) or Ca (Mg)-Cl (+NO3+SO4) type. Concentrations of NO 3 ? , Cl?, SO 4 2? , Na+, and K+ generally show an indistinct grouping with respect to land use types, with very high concentrations observed in the groundwater from residential and agricultural areas. This suggests that those ions are mainly derived from sewage effluents and fertilizers. No specific land use control on the Mg2+ ion distribution is observed, suggesting Mg2+ is originated from natural dissolution of carbonate rocks. The distribution of Ca2+ and HCO 3 ? does not show any distinct land use control either, except for the samples from residential zones, suggesting the Ca2+ and HCO 3 - mainly come from both natural dissolution of carbonate rocks and sewage effluents.  相似文献   

13.
Abstract

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m?1 (control treatment) and 4, 6, and 8 dS m?1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m?1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m?1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m?1, and no further reduction was detected at EC of 8 dS m?1. The significant reductions in Pn corresponded to similar leaf Cl? concentrations (around 409 mmol kg?1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (gs) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in Pn rates. Melon leaves accumulated larger amounts of Cl? than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt‐tolerant than melon.  相似文献   

14.
The aim of this trial was to study the nutritional behavior generated by modifications in the salt concentration in the nutrient solution used for the fertigation of Cordyline fruticosa var. Red Edge plants. Four treatments were tested: T1 [control, 1.5 dS m?1, 14.3 mmol L?1 sodium chloride (NaCl)]; T2 (2.5 dS m?1, 22.2 mmol L?1 NaCl); T3 (3.5 dS m?1, 32.7 mmol L?1 NaCl); and T4 (4.5 dS m?1, 38.2 mmol L?1 NaCl). There is an accumulation of sodium (Na+) in roots, stem, and petiole when salinity increases, which avoid leaf damages. Potassium (K) concentration increases with the intermediate saline treatments in stems and leaves but decreases when plants are fertigated with T4. Calcium (Ca) accumulates in roots with T3 and T4, in stems with T4, and in petioles and leaves with T3. Magnesium (Mg) concentration is greater in stems, petioles, and leaves of T4, but is greater in roots of T3. Plants fertigated with the three saline treatments extract 1.4 times more Na+ than T1 plants. The greatest K+ extraction is observed in T2, followed by T3, and T4. T2, T3, and T4 plants extracted more Ca2+ than T1 plants. Finally, Mg2+ extractions in T3 are twice as much as they are in T1, while in T4 and T2 are much greater.  相似文献   

15.
Summary This study examined the effects of NH inf4 + fertilizers [(NH4)2SO4, (NH4)2HPO4, CO(NH2)2, NH4OH, and NH4NO3] on NH3 loss and the quantity of Ca + Mg, NH inf4 + and NO inf3 sup– in the solution of a calcareous soil (Harkey sicl, Typic Torrifluvent). Various NH4 fertilizers applied at a depth of 5 cm in the soil produced differing NH3 loss characteristics. Applying (NH4)2SO4 (AS) resulted in high volatile NH3 losses as compared with NH4OH (AH) and (NH4)2CO3 (AC). The AS treatment formed an equal molar amount of CaSO4, which increased the mobility of ammonium, while AH and AC treatments caused Ca precipitation and decreased ammonium mobility. Leaching the AS system before NH3 loss could occur resulted in the most rapid nitrification rate. Lower nitrification rates were found with AH and AC than AS under the same conditions. Surface placement of NH4 fertilizers resulted in variable leachate contents of Ca + Mg. Ammonium sulfate reacted with CaCO3 either to solubilize some Ca + Mg or simply to replace exchangeable Ca + Mg with NH4, while AH, AC, and (NH4)2HPO4 (DAP) precipitated essentially an equivalent molar amount of soluble and adsorbed Ca + Mg. Use of NH4NO3, which does not form an insoluble calcium precipitate, resulted in the leaching of an equivalent molar amount of exchangeable Ca + Mg from the Harkey soil.The authors are Professor and former laboratory technician, respectively, at Texas A&M Research Center at El Paso, 1380 A&M Circle, El Paso, TX 79927, USA  相似文献   

16.
Austrian winter pea (Pisum sativum subspecies arvense (L.) Poir) is grown as a cool season annual to produce high protein seed and forage as well as for soil fertility improvement. This legume is grown on a wide range of soil types with many different cropping systems. The objective of these studies was to determine the influence of K levels, with and without P and Ca fertilization, for increased growth, yield, nodulation and nitrogenase activity. Results were from 3 years’ field and greenhouse experiments with a Psammentic Paleustalf (Eufaula series) utilizing Rhizobium leguminosarum (Frank), ATCC 10314 as inoculum. Soil fertility effects on composition and histology of field‐grown nodules are presented.

Available soil P was a limiting plant nutrient in field studies with significant response to K resulting with PK combinations for top growth, tillers, pods, seed yield, nodule mass, and nitrogenase activity levels (C2H2, red.). Multiple regression for nitrogenase (umol C2H4 h‐1) = 1.09 tiller number + 3.37 nodule weight + 2.29 pod number, R2 = 0.837, C.V. = 29.9%. Results from the greenhouse experiments indicated significant responses with increased K application levels when combined with P and Ca fertilization for top growth, nodule weight, number of nodules and nitro‐genase activity. Highly significant correlations resulted with nitrogenase x nodule weight (r=0.538) and nitrogenase x top growth (r=0.359) with multiple regression of treatment effects for nitrogenase (μmol C2H4 h‐1) = 2.73 P + 1.04 K + 4.92 Ca, R2 = 0.797 and C.V. = 48.8%. Soil addition of plant nutrients resulted in significantly increased concentrations of those elements within nodules. Magnesium content was not consistently influenced by P, Ca, and K amendments. Sodium decreased with increased K fertilization. Multiple regression of elemental composition (mg g‐1 nodule) for nitrogenase (pmol C2H4 h‐1) = 0.21 P + 0.86 K + 2.35 Ca ‐ 2.01 Na, R2 = 0.772, C.V. = 55.6%. The proportion of plant nutrients in nodules contained within the nodule cytosol was highest for K (56.2%) and lowest for Ca (21.4%) with intermediate levels of Mg (50.2%), P (45.4%), and Na (37.2%).

Practical application from these data include the requirement of adequate available soil K for increased yield and nitrogen fixation with favorable P and Ca soil levels in Austrian winter pea production.  相似文献   


17.
Abstract

In soilless production systems, water quality can have a major impact on the growth of plants. It has become evident that moderately alkaline water is a problem for tobacco transplant growers in some regions of Kentucky. To determine the level of bicarbonate (HCO3 ?) alkalinity, which is detrimental to burley tobacco transplants, and to better understand the effect of calcium (Ca) and the interaction of HCO3 ? and Ca on the growth of burley tobacco transplants grown in a float system, three levels of CaCl2 (25,75, and 125 mg L?1 Ca++) in factorial combination with five levels of HCO3 ? (0, 122, 244, 366, and 488 mg HCO3 ?L?1) were tested in nutrient solution culture. Four‐week‐old burley tobacco (Nicotiana tabacum L. var. KY‐907) seedlings were transplanted to 18‐L containers filled with aerated Hoagland's solution with the different levels of calcium and HCO3 ? for two weeks. High HCC3 ? alkalinity caused root system damage and plant growth inhibition, but did not induce iron (Fe) chlorosis. A significantly lower concentration of Zinc (Zn) was measured in the shoots as HCO3 ? levels in solution increased. In the presence of high calcium, plant growth was not significantly improved. No significant interaction of HCO3 ? and Ca on growth or nutrient uptake was observed in this study.  相似文献   

18.
This paper focuses on the short-term reaction of fine root and mycorrhiza on changes in soil solution chemistry following application of MgSO4 (Kieserite) and (NH4)2SO4 (ammonium sulfate). The experiments were conducted within the ARINUS Experimental Watershed Area near Schluchsee in the Black Forest (SW Germany). Yellowing of the older needles as related to Mg deficiency was the typical symptom observed within this 45 yr old Norway spruce stand. On the N treated plot the relative mycorrhiza frequency declined and the percentage of nonmycorrhizal root tips increased, whereas in the Mg fertilized plot these parameters did not differ from the control. The observed changes cannot be caused by A1, because elevated concentrations of potentially toxic A1 species and extremely low Ca/A1 molar ratios appeared in the soil solution of both treatments and did not result in reduced growth of long roots as reported from solution culture experiments. Moreover, the A1 content of fine roots did not increase. Therefore, it is concluded that the thresholds for A1 toxicity derived from solution culture experiments with nonmycorrhizal seedlings cannot be transferred to forest stands. A direct toxic effect of elevated NH 4 + concentrations on mycorrhiza is unlikely, but cannot be excluded. Enhanced root growth due to a higher uptake of NH 4 + from soil solution may provide a more plausible explanation for the observed increase in the percentage of nonmycorrhizal root tips after N application. Even though the N content of fine roots did not increase, the diminished K content gives some indirect indication for NH 4 + uptake by the roots. This is also consistent with reduced Mg content due to NH 4 + /Mg2+ antagonism. On the MgSO4 treated plot, Mg contents of the fine roots increased thus reflecting Mg uptake by the deficient stand.  相似文献   

19.
Eustoma grandiflorum (Raf.) Shinn. (lisianthus) is a moderately salt tolerant species that can be produced commercially under irrigation with saline wastewaters prevalent in two salt-affected areas of California. The objective of the present studies was to determine the effect of irrigation with saline waters of two different compositions on the ion accumulation and ion relations of lisianthus ‘Pure White’ and ‘Echo Blue’. The ionic composition of irrigation waters simulated the compositions typical of i) seawater dilutions (SWD) and ii) concentrations of Colorado River water (CCRW). Electrical conductivities (EC) of SWD and CCRW were between 2 and 12 dS · m?1. Plants irrigated with CCRW were higher in Ca2+ compared to plants irrigated with SWD water. Calcium was also higher in ‘Pure White’ than in ‘Echo Blue’. Increasing EC of irrigation water caused a significant decrease in shoot and leaf Ca2+ concentration in ‘Echo Blue’, but had no effect on Ca2+ content of ‘Pure White’ shoots and leaves. Magnesium concentration in ‘Echo Blue’ was higher than in ‘Pure White’. Electrical conductivity did not significantly affect Mg2+ concentration of either cultivar, despite the increasingly higher external concentration. Potassium concentration of young and mature leaves of ‘Echo Blue’ increased as EC increased from 2 to 8 dS · m?1, then decreased significantly once EC exceeded 8 dS · m?1. Potassium concentration of ‘Pure White’ leaves decreased over the range of salinity treatments tested, suggesting that the reduced potassium ion (K+) activity at EC levels of 8 dS · m?1, or less, that resulted in lower leaf?K+ in ‘Pure White’ did not cause a decrease in K+ uptake in ‘Echo Blue’. Increases in external Na+ caused a significant increase in Na+ in ‘Pure White’ leaves and these plants exhibited the best growth even when levels of Na+ were high enough to be considered detrimental for growth.  相似文献   

20.
The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na2SO4), calcium chloride (CaCl2), calcium sulfate (CaSO4), potassium chloride (KCl), potassium sulfate (K2SO4), magnesium chloride (MgCl2), magnesium sulfate (MgSO4)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na2SO4, CaCl2, CaSO4, MgCl2, MgSO4, KCl, and K2SO4, and similarly NaCl, Na2SO4, CaCl2, CaSO4, KCl, K2SO4, MgCl2, and MgSO4 in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.  相似文献   

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