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Selected Abstracts

Calcite and gypsum solubility products in water-saturated salt-affected soil samples at 25°C and at least up to 14 dS m,1

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2010
F. Visconti
Calcite and gypsum are salts of major ions characterized by poor solubility compared with other salts that may precipitate in soils. Knowledge of calcite and gypsum solubility products in water-saturated soil samples substantially contributes to a better assessment of processes involved in soil salinity. The new SALSOLCHEMIS code for chemical equilibrium assessment was parameterized with published analytical data for aqueous synthetic calcite and gypsum-saturated solutions. Once parameterized, SALSOLCHEMIS was applied to calculations of the ionic activity products of calcium carbonate and calcium sulphate in 133 water-saturated soil samples from an irrigated salt-affected agricultural area in a semi-arid Mediterranean climate. During parameterization, sufficiently constant values for the ionic activity products of calcium carbonate and calcium sulphate were obtained only when the following were used in SALSOLCHEMIS: (i) the equations of Sposito & Traina for the free ion activity coefficient calculation, (ii) the assumption of the non-existence of the Ca (HCO 3)+ and CaCO3o ion pairs and (iii) a paradigm of total ion activity coefficients. The value of 4.62 can be assumed to be a reliable gypsum solubility product (pKs) in simple aqueous and soil solutions, while a value of 8.43 can only be assumed as a reliable calcite solubility product (pKs) in simple aqueous solutions. The saturated pastes and saturation extracts were found to be calcite over-saturated, with the former significantly being less so (p IAP = 8.29) than the latter (p IAP = 8.22). The calcite over-saturation of saturated pastes increased with the soil organic matter content. Nevertheless, the inhibition of calcite precipitation is caused by the soluble organic matter from a dissolved organic carbon threshold value that lies between 7 and 12 mm. The hypothesis of thermodynamic equilibrium is more adequate for the saturated pastes than for the saturation extracts. [source]

Brackish water subirrigation for vegetables,

IRRIGATION AND DRAINAGE, Issue 2 2003
R. M. Patel
eaux saumâtres; irrigation souterraine; poivron vert; pommes de terre Abstract As freshwater resources for irrigation are being depleted rapidly, recent emphasis has been on the development of nonconventional water sources: reuse of agricultural drainage water, use of industrial or municipal wastewater, and use of brackish water for irrigation. Experiments conducted in field lysimeters over three seasons sought to investigate the feasibility of using brackish water for growing moderately sensitive crops. Brackish waters, with salinity levels of 1, 5 and 9 dS m,1, were used. In 1993 the effects of a factorial combination of three subirrigation water salinity levels, two water table depths and four NPK fertilizer combinations on salt buildup in an initially nonsaline soil and on green pepper (Capsicum annuum L.) performance were assessed. A gradual increase in soil solution salinity (ECsw) from the water table to the soil surface was evident; however, throughout the growing season, the ECsw did not reach a level that could seriously damage the crop. There was no significant difference in pepper yields due to either salinity of subirrigation water or water table depth. In 1994, two potato (Solanum tuberosum L.) cultivars were grown in the soil, which was salinized with 3.5 dS m,1 water before planting tubers. The salt buildup pattern was similar to that observed in 1993; however, the ECsw levels were higher in 1994 due to the higher initial soil salinity. Moreover, a decrease in ECsw was observed near the water table in lysimeters subirrigated with 1 dS m,1 water. For both cultivars, no significant difference in tuber yield was observed due to either water table depth or subirrigation water salinity. In 1995, three potato cultivars were grown in a nonsaline soil as well as a soil presalinized with 2 dS m,1 water. In the topsoil layer, higher rate of increase in ECsw was observed in the saline soil compared to the nonsaline soil. No significant difference in total tuber yield was observed due to either the initial soil salinity levels or subirrigation water salinity levels. Brackish water with salinity levels of up to 9 dS m,1, when applied through subirrigation, could be used to successfully produce green peppers and potatoes under semiarid to arid conditions. Copyright © 2002 John Wiley & Sons, Ltd. RÉSUMÉ Comme les ressources en eau douce utilisées poor l'irrigation s'épuisent rapidement, les récentes recherches tentent de mettre l'emphase sur le développement de sources d'eau non-conventionnelles: la réutilisation de l'eau de drainage agricole, l'utilisation des eaux usées municipales et des eaux saumâtres pour l'irrigation des cultures. Lors de pénuries d'eau douce les eaux saumâtres ont été utilisées pour l'irrigation souterraine de maïs, mais la salinité de la couche supérieur du sol a été réduite en raison de la pluie. Dans les régions arides et semi-arides cette méthode s'est limitée à quelques essais seulement. En raison des quantités limitées d'eau de bonne qualité, on ne peut irriguer de vastes étendues agricoles en régions arides. Or, si l'utilisation des eaux saumâtres s'avérait un succès il serait possible d'améliorer les rendements agricoles. Il est donc nécessaire d'évaluer l'utilisation des eaux saumâtres dans les systèmes d'irrigation souterrains en milieu aride. Des expériences en lysimètres au cours de trois saisons, dans le but d'étudier la faisabilité d'utiliser des eaux saumâtres pour l'irrigation souterraine de cultures moyennement sensibles, furent entreprises en 1993 et 1994. Des eaux saumâtres avec des niveaux de salinité de 1, 5 et 9 dS m,1, furent utilisés. En 1993, les effets d'une combinaison factorielle de trois niveaux de salinité, deux profondeurs de nappe phréatique et quatre combinaisons de fertilisation NPK ont servi à évaluer l'accumulation de sel dans un sol initialement non-salin où le poivron vert (Capsicum annuum L.) a été cultivé. Une augmentation graduelle de la salinité de la solution du sol, de la nappe d'eau souterraine jusqu'à la surface, fut évidente. Bien que durant la saison de croissance, la conductivité électrique de la solution du sol (ECsw) n'ait pas atteint un niveau qui aurait pu endommager sérieusement la culture. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative les rendements de poivrons. En 1994, deux cultivars de pommes de terre (Solanum tuberosum L.) furent cultivés dans un sol rendu salin, après avoir été irrigué avec une eau d'un niveau de salinité de 3.5 dS m,1, préalablement à la plantation des tubercules. L'accumulation de sel suivit une tendance semblable à celle observée en 1993. Cependant, les niveaux de ECsw enregistrés en 1994 furent plus élevés en raison du taux de salinité initial plus élevé. De plus, une baisse de ECsw fut observée près de la nappe d'eau souterraine dans les lysimètres irrigués avec une eau d'un niveau de salinité de 1 dS m,1. Ni les différents niveaux de salinité ni la profondeur de la nappe d'eau souterraine n'ont affecté de façon significative le rendement de pommes de terre de chacun des cultivars. En 1995, trois cultivars de pommes de terre ont été cultivés dans un soil non salin ainsi que dans un sol rendu salin au moyen d'une eau avec une conductivité électrique de 2 dS m,1. Dans la couche supérieure du sol, un plus important taux d'augmentation de conductivité électrique a été observé dans le sol salin que dans le sol non salin. Il n'y a pas eu de différence significative observée en raison des taux initiaux de salinité ou encore en raison des taux de salinité de l'eau dans le système d'irrigation souterrain. Cette étude suggère que les eaux saumâtres d'un niveau de salinité jusqu'à 9 dS m,1 pourraient être utilisées dans les systèmes d'irrigation souterrains pour la culture du poivron vert et de la pomme de terre en régions semi-arides et arides. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Evaluation of DRAINMOD-S for simulating water table management under semi-arid conditions,

IRRIGATION AND DRAINAGE, Issue 3 2002
M. A. S. Wahba
modèl e dela direction dela table d'eau souterraine; le drainage conventionnel; le drainage contrôlé Abstract The water table management simulation model, DRAINMOD-S, was evaluated under semi-arid conditions using field data from the Maruit experimental field in the western delta of Egypt for three cropping seasons; maize 1999, wheat 1999/2000 and maize 2000. Two water table management systems (conventional drainage (FD) and controlled drainage (CD)) were applied in the study area. The recorded data included daily ground water table depths, drain outflows during flow events, soil salinity to depth of 1.20 m from the soil surface (0.30 m interval), and relative crop yield. DRAINMOD-S was run to simulate the applied water table management systems for the same study periods. The reliability of the model was evaluated by comparing measured and predicted values of the daily ground water table depth, cumulative outflow based on total monthly outflow, soil salinity during each season, and relative crop yield. Good agreement was found between the measured and predicted values. DRAINMOD-S predicted values within an absolute deviation ranged from 11.0 to 16.0 cm for ground water table depth, from 18 to 75 mm for drain outflows, from 0.22 to 1.08 dS m,1 for soil salinity, and from 4.62 to 4.86% for relative crop yield. The model showed the potential for long-term simulation and planning of ground water table management systems under semi-arid conditions of the western delta of Egypt. Copyright © 2002 John Wiley & Sons, Ltd. RÉSUMÉ Le modèle DRAINMOD-S pour simuler la direction de la table d'eau sous des conditions demi-arides á été évalué en utilisant le data des champs experimentaux du Mariut delta denileouest d'Égypte pendant trois saisons agricoles: le maïs 1999, le blé 1999/2000 et le maïs 2000. Deux systèmes de direction de la table d'eau (drainage conventionnel (FD) et drainage contrôlé (CD)) ontété appliqués àla superficie de l'étude. Le data qui s'est remis en ordre s'inclut les mesures des profondeurs de la table d'eau souterraine, les écoulements des drains pendant les évènements de l'écoulement, la salinité du sol au profondeur de 1.20 m souterrain aux intervalles de 30 cm, etles produits agricoles relatifs. DRAINMOD-S S'est mis en courant pour simuler l'application des systèmes de la direction pour la même période d'étude. La véracité du modèle aété évaluée en comparant les valeurs mésurées avec lcelles des produits agricoles sur le profondeur de la table d'eau quotidien, l'écoulement cumulatif basé sur l'écoulement total du mois, la salinité du sol pendant chaque saison, et les produits agricoles relatifs. On a trouvé un bon accord entre les valeurs mésurées et celles qu'on avait prédites avec une déviation absolue qui rangeait de 11.0 à 16.0 cm pour la profondeur de la table d'eau, de 18 à 75 mm pour l'écoulement du drains, et de 0.22 à 1.08 dS m,1, pour la salinité du sol et de 4.62 à 4.86% pour les produits agricoles relatifs. Le modèle a indiqué une éfficacité pour une simulation allongée et pour projeter les systèmes de la direction dela table d'eau souterraine auprès les conditions demi-arides du delta ouest en Egypte. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Assessment of Growth, Physiological and Biochemical Parameters and Activities of Antioxidative Enzymes in Salinity Tolerant and Sensitive Basmati Rice Varieties

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2007
M. P. Singh
Abstract This investigation was undertaken to compare the level of salinity tolerance of the newly bred CSR-30 basmati rice variety with that of the salinity sensitive HBC-19 and Pokkali rice varieties. Twenty-one-day-old hydroponically raised seedlings at 6 and 12 dS m,1 were investigated for growth, photosynthetic rate, chlorophyll content, ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) activity, relative water content (RWC), membrane stability index (MSI), lipid peroxidation, Na/K ratio and activities and gene expression of various isoforms of antioxidative enzymes. Salinity stress led to reduction in shoot length, leaf area, dry weight, RWC, MSI, rate of photosynthesis, chlorophyll content and Rubisco activity in all the three rice varieties. The levels of reduction in these parameters were maximal in HBC-19 followed by those in CSR-30 and Pokkali respectively. Cumulative superoxide dismutase (SOD) activity increased in Pokkali and CSR-30 in consonance with increase in salinity stress while it decreased in HBC-19. The Mn-SOD activity however, was enhanced in all three varieties in the presence of salinity stress while the activities of Fe-SOD, Cu/Zn-SOD and ascorbate peroxidase were decreased in HBC-19 when compared with CSR-30 and Pokkali. The activity of catalase (CAT) was higher in HBC-19 when compared with its activity in CSR-30 and Pokkali. The levels of gene expressions of the three isoforms of SOD ascertained by reverse transcriptase polymerase chain reaction were not necessarily indicative of the activities of the corresponding enzymes. Thus, despite the maximal enhancement in gene expression of Fe-SOD in HBC-19 in response to salinity stress, the activity of this enzyme in HBC-19 remained low. Similarly, despite a marginal increase in gene expression of Cu-Zn SOD in the three varieties, its activity was significantly higher in Pokkali and CSR-30 when compared with that in HBC-19. A significant enhancement in the activity of CAT at 12 dS m,1 in HBC-19 when compared with CSR-30 and Pokkali might confer a degree of tolerance to H2O2 stress in this variety in the presence of higher levels of NaCl at the seedling stage. [source]

Effect of Sodium Chloride Salinity on Seedling Emergence in Chickpea

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2002
H. A. Esechie
Although laboratory (Petri dish) germination as an estimate of seed viability is a standard practice, it may not give an accurate prediction of seedling emergence in the field, especially when saline irrigation water is used. Experiments were conducted to investigate seedling emergence in two chickpea cultivars (ILC 482 and Barka local) in response to varied salinity levels and sowing depths. Seeds were sown in potted soil at a depth of 2, 4 or 6 cm. The salinity treatments were 4.6, 8.4 and 12.2 dS m,1. Tap water (0.8 dS m,1) served as the control. Depth of sowing had a significant effect on seedling emergence. Seeds sown 6 cm deep showed the lowest seedling emergence. Similarly, salinity had an adverse effect on seedling emergence. The lowest seedling emergence percentages were obtained at the highest salinity treatment (12.2 dS m,1). The interaction between salinity treatment and seeding depth was significant. Hypocotyl injury was implicated as a possible cause of poor seedling emergence in chickpea under saline water irrigation and was less severe when pre-germinated seeds were used. ILC 482 appeared to be more tolerant to salinity than Barka local, suggesting that breeding programmes involving regional exchange of germplasm may be helpful. Einfluss einer Natriumchloridversalzung auf den Sämlingsaufgang von Kichererbse Obwohl im Laboratorium (Petrischale) die Keimung an Hand einer Abschätzung der Samenkeimkraft als Standard beurteilt wird, kann dies eine nicht zuverlässige Voraussage des Sämlingsaufganges im Feld sein, insbesondere wenn versalztes Bewässerungswasser verwendet wird. Die Experimente wurden durchgeführt, um das Sämlingsauflaufen von zwei Kichererbsenkultivaren (ILC 482 und Barka local) in der Reaktion gegenüber variierten Versalzungskonzentrationen und Aussaattiefen zu untersuchen. Die Samen wurden in Gefäßkulturen mit einer Tiefe von 2, 4 oder 6 cm angesät. Die Versalzungsbehandlungen betrugen 4.6, 8.4 und 12.2 dS m,1. Unversalztes Wasser (0.8 dS m,1) diente als Kontrolle. Die Aussaattiefe hatte einen signifikanten Einfluss auf das Auflaufen der Sämlinge. Samen mit einer 6 cm Tiefe Ansaat hatten den schlechtesten Auflauf. Entsprechend zeigte auch die Versalzung einen ungünstigen Einfluss auf den Sämlingsaufgang. Die schlechteste Keimlingsaufgangsrate wurde bei der höchsten Versalzungsbehandlung (12.2 dS m,1) gefunden. Die Interaktion zwischen Versalzungsbehandlungen und Saattiefe war signifikant. Die Hypokotytbeschädigung wird als eine mögliche Ursache der schwachen Auflaufraten bei Kichererbse unter dem Einfluss versalzten Bewässerungswassers erklärt; die Wirkung war weniger schwer, wenn vorgekeimte Samen verwendet wurden. ILC 482 scheint toleranter gegenüber Versalzung zu sein als Barka local; es erscheint zweckmäßig, Zuchtprogramme unter Verwendung regionaler Genotypen durchzuführen. [source]

Effects of Salinity and Mixed Ammonium and Nitrate Nutrition on the Growth and Nitrogen Utilization of Barley

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2001
A. Ali
The absorption and utilization of nitrogen (N) by plants are affected by salinity and the form of N in the root medium. A hydroponic study was conducted under controlled conditions to investigate growth and N uptake by barley (Hordeum vulgare L.) supplied with five different NH4+ -N/NO3, -N ratios at electrical conductivity of 0 and 8 dS m,1. The five NH4+ -N/NO3 -N ratios were 0/100, 25/75, 50/50, 75/25 and 100/0, each giving a total N supply of 100 mg N l,1 in the root medium. A mixed N supply of NH4+ and NO3, resulted in greater accumulation of N in plants than either NO3, or NH4+ as the sole N source. Plants produced a significantly higher dry matter yield when grown with mixed N nutrition than with NH4+ or NO3, alone. Total dry matter production and root and shoot N contents decreased with increasing salinity in the root medium. The interaction between salinity and N nutrition was found to be significant for all the variables. A significant positive correlation (r=0.97) was found between nitrogen level in the plant shoot and its dry matter yield. Wachstum und Stickstoffausnutzung bei Gerste in Abhängigkeit von Versalzung und Michungen von Ammonium und Nitrat Aufnahme und Nutzung von N durch Pflanzen wird von der Versalzung und N-Form im Wurzelbereich bestimmt. Es wurde in Hydrokultur unter kontrollierten Bedingungen Wachstum und N-Aufnahme durch Gerste (Hordeum vulgare L.) bei Anwendung von fünf unterschiedlichen NH4+ -N/NO3, -N Verhältnissen bei einer elektrischen Konduktivität von 0 und 8 dS m,1 untersucht. Die Gesamtmenge von 100 mg N l,1 im Wurzelmedium wies NH4+ -N/NO3, -N Verhältnisse von 0/100, 25/75, 50/50, 75/25 und 100/0 auf. Mischungen von NH4+ und NO3, führten zu einer größeren Aufnahme durch die Pflanzen als bei alleiniger Anwendung von NO3, oder NH4+. Die Pflanzen produzierten signifikant mehr Gesamttrockenmasse mit Mischungen der beiden N-Formen im Vergleich zu alleiniger Anwendung von NH4+ oder NO3,. Die Gesamttrockenmasse sowie die N-Gehalte von Wurzel und Sproß nahmen mit steigender Versalzung ab. Versalzungs- und N-Versorgungs-Interaktion war signifikant in allen Versuchsbedingungen. Eine signifikante positive Korrelation (r=0,97) wurde zwischen Stickstoffkonzentration und der Trockenmasseproduktion der Pflanze gefunden. [source]

Effect of Secondary Salinization on Photosynthesis in Fodder Oat (Avena sativa L.) Genotypes

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2000
A. Chatrath
The effect of secondary salinization on photosynthesis was studied in fodder oat genotypes Kent, JHO-829, JHO-881, UPO-94 and OS-6 at the flower initiation stage. With an increase in the electrical conductivity (EC) of irrigation water, the net photosynthesis rate (PN) and the transpiration rate (E) of all the genotypes decreased. The intercellular CO2 concentration (Ci) increased in all genotypes at 10 dS m,1. Stomatal resistance (Rs) had a strong negative correlation with PN and E. The increase in Ci together with the increase in the Rs shows that at higher EC non-stomatal factors also start contributing to the limitation of photosynthesis. This study suggests that secondary salinization effects are strongly under stomatal control at lower saline water irrigation levels, but at higher levels non-stomatal factors may come into play. [source]

Proton release by N2 -fixing plant roots: A possible contribution to phytoremediation of calcareous sodic soils

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2003
Manzoor Qadir Prof. Dr.
Abstract With a world-wide occurrence on about 560 million hectares, sodic soils are characterized by the occurrence of excess sodium (Na+) to levels that can adversely affect crop growth and yield. Amelioration of such soils needs a source of calcium (Ca2+) to replace excess Na+ from the cation exchange sites. In addition, adequate levels of Ca2+ in ameliorated soils play a vital role in improving the structural and functional integrity of plant cell walls and membranes. As a low-cost and environmentally feasible strategy, phytoremediation of sodic soils , a plant-based amelioration , has gained increasing interest among scientists and farmers in recent years. Enhanced CO2 partial pressure (PCO2) in the root zone is considered as the principal mechanism contributing to phytoremediation of sodic soils. Aqueous CO2 produces protons (H+) and bicarbonate (HCO3 - ). In a subsequent reaction, H+ reacts with native soil calcite (CaCO3) to provide Ca2+ for Na+ Ca2+ exchange at the cation exchange sites. Another source of H+ may occur in such soils if cropped with N2 -fixing plant species because plants capable of fixing N2 release H+ in the root zone. In a lysimeter experiment on a calcareous sodic soil (pHs = 7.4, electrical conductivity of soil saturated paste extract (ECe) = 3.1 dS m -1, sodium adsorption ratio (SAR) = 28.4, exchangeable sodium percentage (ESP) = 27.6, CaCO3 = 50 g kg -1), we investigated the phytoremediation ability of alfalfa (Medicago sativa L.). There were two cropped treatments: Alfalfa relying on N2 fixation and alfalfa receiving NH4NO3 as mineral N source, respectively. Other treatments were non-cropped, including a control (without an amendment or crop), and soil application of gypsum or sulfuric acid. After two months of cropping, all lysimeters were leached by maintaining a water content at 130% waterholding capacity of the soil after every 24±1 h. The treatment efficiency for Na+ removal in drainage water was in the order: sulfuric acid > gypsum = N2 -fixing alfalfa > NH4NO3-fed alfalfa > control. Both the alfalfa treatments produced statistically similar root and shoot biomass. We attribute better Na+ removal by the N2 -fixing alfalfa treatment to an additional source of H+ in the rhizosphere, which helped to dissolve additional CaCO3 and soil sodicity amelioration. Protonenabgabe durch N2 -fixierende Pflanzenwurzeln: ein möglicher Beitrag zur Phytomelioration von kalkreichen Natriumböden Bei einem weltweiten Vorkommen auf etwa 560 Millionen Hektar sind Natriumböden durch einen Überschuss an Natrium (Na+) gekennzeichnet, der das Wachstum und den Ertrag von Kulturpflanzenbeständen nachteilig beeinflussen kann. Die Melioration solcher Böden erfordert Calcium (Ca2+), um überschüssiges Na+ von Kationen-Austauscherplätzen zu verdrängen. Außerdem spielt Ca2+ eine wichtige Rolle bei der Verbesserung der strukturellen und funktionellen Integrität pflanzlicher Zellwände und Membranen. Als kostengünstige und umweltfreundliche Strategie hat die Phytomelioration von Natriumböden , eine auf Pflanzen beruhende Melioration , in den letzten Jahren zunehmendes Interesse bei Wissenschaftlern und Landwirten gefunden. Ein erhöhter CO2 -Partialdruck (PCO2) in der Rhizosphäre wird als hauptsächlicher Mechanismus angesehen, der zur Phytomelioration von Natriumböden beiträgt. In Wasser gelöst, erzeugt CO2 Protonen (H+) und Bikarbonate (HCO3 - ). Anschließend reagiert H+ mit nativem Calcit (CaCO3), wobei sich Ca2+ löst und Na+ von Austauscherplätzen verdrängt. Eine weitere H+ -Quelle könnte die H+ -Abgabe von Wurzeln N2 -fixierender Pflanzen sein, da diese in der Lage sind, H+ in die Rhizosphäre abzugeben. In einem Lysimeterversuch mit einem kalkreichen Natriumboden (pHs = 7, 4; ECe = 3, 1 dS m -1; SAR = 28, 4; ESP = 27, 6; CaCO3 = 50 g kg -1) wurde die Möglichkeit einer Phytomelioration mit N2 -fixierender Luzerne (Medicago sativa L.) im Vergleich zu einer mit mineralischem N ernährten Luzerne (NH4NO3) untersucht. In weiteren Varianten (Applikation von Gips bzw. Schwefelsäure) wurde die chemische Melioration einer nicht behandelten Kontrolle gegenübergestellt. Beide Ernährungsformen führten zu statistisch ähnlicher Wurzelund Sprossmasse der Luzerne. Nach zweimonatigem Pflanzenwachstum erfolgte alle 24±1 h eine Dränung der Lysimeter durch Zugabe einer Wassermenge von 130% der maximalen Wasserkapazität zum Boden. Hinsichtlich der Effizienz, Na+ über Auswaschung aus dem Boden zu entfernen, zeigte sich folgende Reihenfolge: Schwefelsäure > Gips = N2 -fixierende Luzerne > NH4NO3 -ernährte Luzerne > Kontrolle. Wir führen das bessere Meliorationsergebnis in der Variante der N2 -fixierenden Luzerne auf eine zusätzliche H+ -Quelle in der Rhizosphäre zurück, die zur Lösung von zusätzlichem CaCO3 beitrug. [source]

The effect of salinity on the growth, yield and essential oils of turnip-rooted and leaf parsley cultivated within the Mediterranean region

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2009
Spiridon A Petropoulos
Abstract BACKGROUND: Turnip-rooted parsley, a field-crop of northern Europe, has recently been introduced to the Mediterranean region for fresh consumption or production of essential oil. Because of soil salinity within this area, the sensitivity of turnip-rooted and two other parsley subspecies (plain- and curly-leafed) to salt was studied. RESULTS: NaCl or CaCl2 additions to the irrigation water raised the electrical conductivity (EC) in increments from 0.5 dS m,1 to 4.5 dS m,1 (year 1) or 6.0 dS m,1 (year 2), reducing parsley foliage weight in year 2, but increasing the root weight of turnip-rooted parsley in year 1. Raising the EC with NaCl increased the yield of foliar essential oil from curly-leafed parsley (both years), but not from the other cultivars. CaCl2 had less effect on oil yield. The relative concentrations of the principal aroma constituents (,-phellandrene, myristicin, ,-myrcene and apiole) of the foliar essential oil were affected by NaCl or CaCl2 in a way that differed between cultivars. Oil yield from parsley roots was very low and apparently unaffected by salinity. CONCLUSION: All three parsley subspecies are moderately sensitive to salinity, but may be cultivated at <4.5 dS m,1 EC. Salinity may assist oil production by increasing oil yield (curly-leafed parsley) and positively affecting certain aroma constituents. Copyright © 2009 Society of Chemical Industry [source]

Effects of salt stress on purslane (Portulaca oleracea) nutrition

ANNALS OF APPLIED BIOLOGY, Issue 1 2009
M. Teixeira
Abstract The objective of this study was to determine the influence of saline stress on the chemical composition of purslane (Portulaca oleracea), in particular the mineral composition. Four salinity levels were investigated using irrigation solutions with electrical conductivity values of 0.8, 6.8, 12.8 and 24.2 dS m,1 and two planting dates (May and July) were tested. Samples of full-grown leaf and stems of purslane were harvested after 7 and 15 days of the saline treatment exposure. Chemical analysis (dry matter basis) of leaves showed significant differences among the different saline treatments for all the characteristics measured. Salinity levels, planting date and harvest time significantly influenced (P < 0.05) the levels of crude protein, total lipids, ash and carbohydrate content. Salinity treatments did not significantly (P > 0.05) affect the water content of purslane leaves. The crude protein content of purslane leaves decreased with increasing salinity levels and time of exposure to treatment. However, carbohydrates and mineral residue content increased. An unusual phenomenon was noted for intermediate salinity levels, whereby an increase in total lipid content was measured in leaves of plants exposed to salinity treatments of 6.8 and 12.8 dS m,1. The highest mineral residue content was seen in leaves of purslane exposed to the highest salinity treatment. The mineral composition was also affected by salinity levels, Na and Cl uptake, and accumulation increased with increasing salinity in irrigation solution; Mg concentration was not significantly (P > 0.05) affected by salinity levels, although a slight increase was seen, and Ca, K and Zn levels significantly (P < 0.05) decreased. Ca and Zn preferentially accumulated in the leaves, while K and Na values were higher in the stems. A significant increase (P < 0.05) in relative ratio of Na/K, Mg/K, Na/Ca and Mg/Ca was observed with increasing salinity levels. A decrease in the yield of purslane was only observed for the most severe saline treatment, where the highest ratio of Mg/Ca was seen. This study reveals that purslane is relatively tolerant to conditions of moderate salinity, thus improving its potential to become a key vegetable crop for animal and human consumption. [source]