Growth and macronutrient contents of faba bean plants: Effects of salinity and nitrate nutrition

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.     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao (Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Bedeutung von Kaliumaufnahmerate,Wurzelwachstum und Wurzelhaaren für das Kaliumaneignungsvermögen verschiedener Pflanzenarten

Effect of K uptake rate, root growth and root hairs on potassium uptake efficiency of several plant species Pot experiments with maize, rape, tomato, rye-grass and onion plants were carried out to evaluate the influence of – rate of K uptake per cm of root, – cm root per mg shoot dry weight and – mean root age (as a measure of the time roots absorb potassium) on potassium uptake efficiency of these plants. Percent K in shoot dry matter was used to indicate K uptake efficiency. No close correlation was observed between one of these factors to K concentration in shoot dry matter. The product of K uptake rate and root-shoot ratio was closely related to the K concentration of shoots. However, regression lines for maize, rape and onion were different. One single regression line was found when K concentration in shoot was related to the product of K uptake rate, root-shoot ratio and mean root age. It is therefore concluded that K uptake of plants depends on all three of these factors. In different species the proportion of these factors were markedly different. The plant factors in turn were affected by the K nutritional status of the plants. K uptake rate increased whereas root-shoot ratio and mean root age decreased with increasing K supply of the soil. K uptake rate per cm root was strongly affected by root hairs. The radial distance of the K (Rb) depletion zone of the soil adjacent to the root surface also increased with the length of the root hairs. It is therefore concluded that root hairs substantially affect the spatial access of potassium in soil by the plant.     

钾、镁交互作用对橡胶幼苗生长及养分吸收的影响

  【目的】  我国植胶区砖红壤钾、镁缺乏现象日益突出，研究钾、镁缺乏对橡胶幼苗根系形态和养分吸收的影响，可为橡胶平衡施肥和优质高产栽培提供理论依据。  【方法】  选用‘热研7-33-97’橡胶 (Hevea brasiliensis) 幼苗为研究材料，在人工气候箱内用营养液培养。采用二因素二水平的析因试验设计，设置4个处理:对照 (CK)、缺钾 (–K)、缺镁 (–Mg) 和缺钾镁 (–K-Mg)，培养3个月后，取样测定橡胶幼苗干物质量、根系构型参数、根系活力和养分含量等指标。  【结果】  1) 与CK相比，–K和–K-Mg处理显著降低了单株干物质量和根冠比，干物质量降幅分别为8.4%和27.5%，根冠比降幅分别为20.4%和26.9%，而–Mg处理对干物质量和根冠比均无显著影响；K、Mg交互作用对茎干、根和单株干物质量及根冠比均有显著影响 (P < 0.05)。2) 与CK相比，各缺素处理均显著降低了橡胶幼苗吸收根 (直径 < 2 mm) 的根长、根表面积、根体积、总根尖数及根系活力等根系构型参数，而不同程度增加了平均根粗。方差分析结果表明，K、Mg交互作用对吸收根的根长、根表面积、根体积及总根尖数有极显著影响 (P < 0.01)。3) 各处理下氮和镁、磷和钾以及钙分别在叶片、根系以及茎皮中的平均分配比例高于其他器官。各缺素处理下，地上部的养分占比呈增加趋势。4) 与CK相比，–K处理显著增加了橡胶幼苗单株氮、磷和镁的积累，–K-Mg处理则显著降低了单株氮积累，各缺素处理均显著增加了单株钙的积累；K、Mg交互作用对氮、磷、钙和镁的积累有显著或极显著影响。  【结论】  钾、镁营养显著影响橡胶幼苗对养分的吸收，缺钾、缺镁显著抑制橡胶幼苗特别是根系的生长发育，同时缺钾缺镁加重抑制效果。因此，橡胶生产上不仅要保证培养基质或土壤的矿质营养充足，还要重视钾、镁元素间平衡关系。     

Adaptive attributes of tropical forage species to acid soils I. Differences in plant growth,nutrient acquisition and nutrient utilization among C4 grasses and C3 legumes

Low supply of nutrients is a major limitation of forage adaptation and production in acid soils of the tropics. A glasshouse study was conducted to find differences in plant growth, nutrient acquisition and use, among species of tropical forage grasses (with C₄ pathway of photosynthesis) and legumes (with C₃), when grown in two acid soils of contrasting texture and fertility. Twelve tropical forage legumes and seven tropical forage grasses were grown in sandy loam and clay loam Oxisols at low and high levels of soil fertility. After 83 days of growth, dry matter distribution among plant leaves, stems, and roots, leaf area production, shoot and root nutrient composition, shoot nutrient uptake, and nutrient use efficiency were measured. Soil type and fertility affected biomass production and dry matter partitioning between roots and shoots. The allocation of dry matter to root production was greater with low soil fertility, particularly in sandy loam. The grasses responded more than the legumes to increased soil fertility in both shoot and root biomass production. Leaf area production and the use of leaf biomass for leaf expansion (specific leaf area) were greater in legumes than in grasses, irrespective of soil type and fertility. But soil type affected shoot biomass production and nutrient uptake of the grasses more than those of the legumes. There were significant interspecific differences in terms of shoot nutrient uptake. The grasses were more efficient than legumes in nutrient use (grams of shoot biomass produced per gram of total nutrient uptake) particularly for nitrogen (N) and calcium (Ca).     

Soil Aluminum Effects on Growth and Nutrition of Cacao

In acid soils, Al toxicity and nutrient deficiencies are main constraints for low yield of cacao ( Theobroma cacao L.). A controlled growth chamber experiment was conducted to evaluate the effect of three Al saturations (0.2, 19, and 26%) adjusted by addition of dolomitic lime on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area (total leaf area/total leaf dry wt), and leaf area ratio (total leaf area/shoot+root wt). Increasing soil Al saturation decreased uptake of elements. Nutrient influx (IN) and transport (TR) decreased significantly for K, Ca and Mg, and showed an increasing trend for S and P as soil Al saturation increased. However, increasing soil Al saturation significantly increased nutrient use efficiency ratio (ER, mg of shoot weight produced per mg of element in shoot) of Ca, Mg and K and decreased ER for other elements. Reduction of soil acidity constraints with addition of lime and fertilizers appear to be key factors in improving cacao yields in infertile, acidic, tropical soils.     

Effects of Zinc Application on Growth,Absorption and Distribution of Mineral Nutrients Under Salinity Stress in Soybean (Glycine Max L.)

The purpose of the present work was to evaluate effects of zinc application on growth and uptake and distribution of mineral nutrients under salinity stress [0, 33, 66, and 99 mM sodium chloride (NaCl)] in soybean plants. Results showed that, salinity levels caused a significant decrease in shoot dry and fresh weight in non-zinc application plants. Whereas, zinc application on plants exposed to salinity stress improved the shoot dry and fresh weight. Potassium (K) concentration, K/sodium (Na) and calcium (Ca)/Na ratios significantly decreased, while sodium (Na) concentration increased in root, shoot, and seed as soil salinity increased. Phosphorus (P) concentration significantly decreased in shoot under salinity stress. Moreover, calcium (Ca) significantly decreased in root, but increased in seed with increased salinization. Iron (Fe) concentration significantly decreased in all organs of plant (root, shoot, and seed) in response to salinity levels. Zinc (Zn) concentration of plant was not significantly affected by salinity stress. Copper (Cu) concentration significantly decreased by salinity in root. Nonetheless, manganese (Mn) concentration of root, shoot, and seed was not affected by experimental treatments. Zinc application increased Ca/Na (shoot and seed) ratio and K (shoot and seed), P (shoot), Ca (root and seed), Zn (root, shoot, and seed) and Fe (root and shoot) concentration in soybean plants under salinity stress. Zinc application decreased Na concentration in shoot tissue.     

钙信号抑制剂加剧低钾胁迫对烟草幼苗光合特性及钾吸收的影响

  【目的】  研究低钾胁迫抑制钙信号传导对植株幼苗叶片光合特性及钾吸收的影响,为缓解作物的低钾胁迫提供理论依据。  【方法】  以烟草品种K326为试验材料进行了室内水培试验。烟草幼苗先在营养液正常钾(K+ 5 mmol/L)和缺钾(K+ 0.15 mmol/L)营养液中生长8 天,然后在营养液中分别施加钙通道有机阻断剂Vp、钙通道无机阻断剂LaCl₃和钙离子螯合剂(EGTA)钙信号抑制剂,继续生长4天后取样,测定植株干鲜重、电导率、活性氧含量、叶片抗氧化酶活性、叶片光合特性等指标和植株地上、地下部钾素浓度及钾离子吸收相关基因表达量。  【结果】  1)不添加钙通道抑制剂或螯合剂条件下,低钾胁迫的烟株地上部和根系干重较常钾水平显著降低了59.29%、39.82%,鲜重显著降低了51.58%、48.19%,除水汽压饱和亏外的其余5项光合特性指标显著降低,植株地上部和根系钾含量分别显著降低了39.31%和77.05%,而叶中可溶性蛋白、相对电导率、过氧化氢含量则显著增加,NKT2、NtKC1、NtHAK1、NtHAK5基因的相对表达量分别增加了2.09、3.32、3.23、12.34 倍。2)常钾水平下,3个钙抑制剂处理未明显影响地上部和根系干鲜重,而低钾水平下,钙抑制处理的地上部鲜重和干重显著高于无钙抑制剂对照。两个钾水平下,与各自对照相比,3个钙抑制剂处理的叶片相对电导率、活性氧积累量均显著增加,抗氧化酶SOD和POD活性、叶绿素含量显著减少,光合特性指标(除水汽压饱和亏外)明显降低。3)两个钾水平下,3个钙信号抑制剂处理的烟株地上部和根系钾含量均显著低于其对照,低钾胁迫下平均降低幅度分别达到25.54%和53.36%。低钾胁迫下,钾离子通道基因NKT2、NtKC1和转运蛋白基因NtHAK1、NtHAK5在根系中的相对表达量分别平均降低了60.60%、50.62%、38.61%、69.79%,钙通道相关基因NtCNGC1和NtCNGC11在根中的相对表达量分别平均降低了95.36%和87.04%。  【结论】  低钾胁迫明显影响烟株幼苗生长、光合作用及对钾素的吸收和积累。低钾水平下,外施钙通道抑制剂或螯合剂可进一步降低烟草叶片抗氧化酶活性,减弱烟株叶片光合作用,并抑制根中钾吸收相关基因的表达和烟株对钾素的吸收。     

EFFECTS OF SALINITY AND CALCIUM ON THE GROWTH AND CHEMICAL COMPOSITION OF PISTACHIO SEEDLINGS

Poor quality of irrigation water (high salinity) has reduced the yields of pistachio over recent years, especially in Kerman. The effects of four salinity levels [0, 30, 60, and 90 mM sodium chloride (NaCl)] and three calcium (Ca) levels [0, 0.5, and 1 mM Ca as calcium nitrate (Ca(NO₃)₂.4H₂O)] on growth and chemical composition of pistachio seedlings cv. ‘Badami’ were studied in sand culture under greenhouse conditions in completely randomized design (CRD) with four replications. After 170 days, leaf area, leaf number, shoot and root dry weights were determined. Also shoot and root sodium (Na), potassium (K), Ca, and magnesium (Mg) concentrations were measured. Results showed salinity decreased all growth parameters. Ca application increased shoot and root Ca concentrations and root K concentration, while Ca application decreased shoot K concentration and shoot and root Mg concentrations. Salinity decreased shoot Ca, root K, and root Mg concentrations, while salinity increased shoot and root total sodium uptake, and shoot and root Cl concentrations.     

GROWTH,NUTRIENT ACQUISITION,AND PHYSIOLOGICAL RESPONSES OF HYDROPONIC GROWN TOMATO TO SODIUM CHLORIDE SALT INDUCED STRESS

□ Growth and nutrient acquisition of tomato (Lycopersicon esculentum L.) cv ‘Amani’ were studied under induced salt stress in Hoagland's solution. The plants were treated for 37 days with salinity induced by incorporating different concentrations [0.0 (control), 50, 100, 150, or 200 mM] of sodium chloride (NaCl) to the nutrient solution. Slight reduction was obtained in growth represented by (shoot length and number, leaf number, and dry weight) when seedlings were directly exposed to NaCl stress from 0.0 to 100 mM. At higher concentrations (150 or 200 mM), growth parameters were adversely affected and seedlings died thereafter. Elevated salinity significantly reduced crude protein and fiber in shoots and roots. Tomato shoot and root contents of potassium (K), iron (Fe), and ash were reduced significantly in response to increased levels of salinity. Tissue contents of sodium (Na) and chloride (Cl) increased with elevated salinity treatments.     

水稻耐盐性的机理

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.     

Aluminium Induced Magnesium Deficiency in Oats

It was the objective to study the effect of Al on Mg uptake by plants, precluding as far as possible the effect of Al on root growth. Oat plants were grown in a complete standard nutrient solution without any differential treatment, in order to obtain a set of plants which did not differ in the size, the morphology and the physiology of the root system. After the first harvest at the beginning of the stem elongation stage 4 different treatments were introduced: pH 5.5-6.0, pH 5.5-6.0 without Mg, pH 3.8-4.1, pH 3.8-4.1 + 0.3 mmole Al/l. Apart from these variations the composition of the nutrient solution remained unaltered. After another 10 days 2 vessels of each treatment were harvested. The final harvest was 14 days after the beginning of the differential treatments. The growth (in terms of dry matter yield) of neither the shoots nor the roots was adversely affected by the differential treatments, although the plants in the Al and Mg₀ treatments showed distinct symptoms of nutritional disorder. The plants in the low and the high pH treatments differed neither in Mg uptakte nor in Mg concentration in the plants. However, the addition of Al to the nutrient solution reduced Mg uptake in the shoots to about 30% of that in the Al₀ treatments, while there was a net loss of Mg in the roots in spite of the fact that dry matter increased. This means that net uptake of Mg was less than was translocated to the shoot during the period of differential treatments. With no Al in the nutrient solution the Mg concentration in the shoots declined by 3–8% between the first and the final harvest, whereas it increased by 22–35% in the roots. If, however, Al was added to the nutrient solution the Mg concentration dropped by 46% in the shoots and 70% in the roots. With the exception of Ca in the roots, the differential treatments had no effect on the uptake and concentration of Ca, K and P in the plants. In terms of dry matter the differential treatments did not influence root growth and it was concluded that Al had a direct effect on Mg uptake by either inactivating or competing for uptake sites or carriers.     

Mineral‐nutrient synergism and dilution responses to nitrogen fertilizer in field‐grown maize

Nitrogen (N)‐fertilizer applications to field‐grown maize may result in a dilution response whereby essential mineral‐element concentrations in shoots would decrease as shoot‐dry‐matter accumulation increased. To investigate this, the effect of N‐fertilizer treatments (no N or fertilizer rate based upon 5.3 or 8.5 t ha^–1 yield goal) on maize (Zea mays L.) shoot dry weight and shoot mineral concentrations (N, P, K, S, Mg, Ca, and Mn) at the sixth leaf (V6), twelfth leaf (V12), and tassel (VT) development stages were investigated in a 2‐year study conducted at Brookings, South Dakota (USA). With increasing N‐fertilizer application rates, shoot dry weight was greater and shoot P and K concentrations decreased. A possible explanation of this dilution response is that planting‐time P and K fertilizers, which were applied in a band near the seed furrow, may have enhanced the uptake of P and K in a manner that was independent of N‐fertilizer treatments. Increased shoot‐dry‐weight production due to the application of N fertilizers, if P and K uptake were similar across N‐fertilizer treatments, would lead to decreased shoot P and K concentrations in N‐sufficient compared with N‐deficient plants. Conversely, N‐fertilizer‐induced increases in shoot dry weight were accompanied by increased shoot concentrations of N, Ca, and Mn. This synergistic response between dry‐weight accumulation and shoot N concentration was present at all leaf developmental stages studied, while that for Ca was present only at VT. Thus, N fertilizer applications that increase shoot dry weight can affect the dilution and synergistic responses of specific mineral nutrients in maize shoots. Crop developmental stage as well as the location of these specific mineral nutrients in the soil profile might play important roles in mediating these responses.     

Influences of Potassium Chloride Fertilization on Mycorrhizal Formation in a Tropical Alfisol

This study examines the influence of different amounts of potassium chloride (KCl) fertilization on plant growth, nutrient accumulation and content, nutrient ratios, and root colonization by indigenous arbuscular mycorrhizal (AM) fungi in maize (Zea mays L.). KCl was applied at the rate of 0, 0.25, 0.50, 1.00, 1.50, and 1.75 mg/kg of soil. Effect of KCl on indigenous AM formation and function was evaluated in terms of the extent of root length colonization, plant growth, and nutrient uptake. Increasing concentration of KCl fertilization proportionately limited the total root length colonized by AM fungi as well as the root length with different AM fungal structures. Maize plants raised on soils amended with different concentrations of KCl were significantly taller than those raised on unamended soils. KCl application also significantly increased the total root length and root dry weight. Nevertheless, KCl fertilization did not significantly alter the root/shoot ratios. Higher concentrations of nitrogen (N), phosphorus (P), and potassium (K) were evident in shoot and root tissues of maize (except shoot N) raised on KCl-amended soils. Phosphorus concentrations in shoots and roots significantly influenced mycorrhization and root length colonized by different AM fungal structures, and such an effect was evident for root N. KCl fertilization increased the efficiency of N and P accumulation. No significant change was evident in the K:N ratios of shoots or roots, whereas the K:P ratios were significantly altered in shoots or roots in response to KCl application.     

Silicon effect on growth,nutrient uptake,and yield of peanut (Arachis hypogaea L.) under aluminum stress

Abstract

The objective of this study was to investigate the effect of silicon (Si) on growth, nutrient uptake, and yield of peanut under aluminum (Al) stress. Peanut (Arachis hypogaea L. cv. Zhonghua 4) raised with or without Si (1.5?mM) in the growth chamber under 0 and toxic Al (0.3?mM) levels. Aluminum stress significantly decreased the biomass and root dry weight by 12.9% and 10.7%, and the pod yield, number of mature pod per plant and seed number of per pod by 16.7%, 10.7%, and 13.9%. The content of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) was significantly decreased, but that of Al increased markedly in shoots and roots of peanut after Al exposure at seedling, flower-needle and pod-setting stage. Under Al stress condition, Si application protected peanut by improving nutrient uptake at different growth stages and favoring the partitioning of dry mass to pod and the allocation of tissue N, P, K, Ca, and Mg to shoots and pod and decreasing Al uptake and accumulation.     

Influence of Iron Fertilization on Cadmium Uptake by Rice Seedlings Irrigated with Cadmium Solution

A pot experiment investigated the effects of iron (Fe) fertilization on cadmium (Cd) uptake by rice seedlings irrigated with Cd solution. Shoot dry weight was significantly affected by Fe addition, and root dry weight was affected by Cd addition. Iron supply was the dominant factor affecting the length of the longest leaf and the soil and plant analyzer development (SPAD) value. Cadmium concentrations were much greater in roots than in dithionite–citrate–bicarbonate (DCB) extracts or shoots, and a significant correlation was found between shoot Fe and Cd concentrations. Enhanced Cd uptake observed at high Fe supply implies that enhanced Fe nutrition may counteract the adverse effects of Cd on plants.     

Effects of Salinity and Copper on Growth and Chemical Composition of Pistachio Seedlings

The effects of five salinity levels and four copper levels on growth and chemical composition of ‘Ghazvini, pistachio seedlings were studied under greenhouse conditions in a completely randomized design with three replications. Leaf area, stem height, shoot and root dry weights were determined on 24th week after planting. Copper (Cu), phosphorus (P), sodium (Na), and chlorine (Cl) total uptake in shoot and root of plant were measured. The results showed that salinity decreased growth parameters. Low levels of Cu application had no significant effect on leaf area, shoot and root dry weights while decreased stem height. The highest level of Cu (7.5 mg Cu kg^?1 soil) significantly increased leaf area and shoot dry weight but decreased stem height. Salinity decreased Cu and P uptake in the shoot and root, but increased total sodium and chloride uptake. Cu application increased shoot total P uptake and decreased root total Na uptake.     

Growth,sodium, and potassium uptake and translocation in salt stressed tomato

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.     

Effect of Superphosphate and Arbuscular Mycorrhizal Fungus Glomus mosseae on Phosphorus and Arsenic Uptake in Lentil (Lens culinaris L.)

Arsenic (As)-contaminated irrigation water is responsible for high As levels in soils and crops in many parts of the world, particularly in the Bengal Delta, Bangladesh and West Bengal, India. While arbuscular mycorrhizal (AM) fungi markedly improve phosphorus (P) uptake, they can also alleviate metal toxicity. In this study, the effects of superphosphate and inoculation with the AM fungus Glomus mosseae on P and As uptake of lentil were investigated. Plant height, shoot dry weight, shoot/root P concentration, and shoot P content increased due to mycorrhizal inoculation. However, As concentration in roots/shoots and root As content were reduced, plant height, shoot dry weight, shoot/root P concentration/content, and root As concentration and content increased due to superphosphate application. Root P concentration decreased with increasing As concentration. It was apparent that As concentration and content in shoots/roots increased with increasing As concentration in irrigation water. Superphosphate interaction with G. mosseae reduced the role of mycorrhizal infection in terms of enhancing P nutrition and reducing uptake of potentially toxic As into plant parts. The role and relationship of mycorrhizal in respect of P nutrition and As remediation efficiency in plant parts was established. In conclusion, it was worth alluding to that lentil with AM fungal inoculation can reduce As uptake and improve P nutrition. However, in retrospect superphosphate increased P and As uptake and decreased the role of the mycorrhizal association. This resulted in stimulating increased P uptake while decreasing As uptake in lentil.     

Sulfur metabolism in Allium cepa is hardly affected by chloride and sulfate salinity

Salinity as a major agricultural problem can affect crop growth and quality. Onion (Allium cepa L.) plant contains a wide variety of sulfur-containing compounds which may be involved in plant protection against salt stress. In the current study, a similar reduction in growth caused by chloride and sulfate salts was observed when onion was exposed to equimolar concentrations of Na⁺. Also, no difference was observed for shoot/root ratio and dry matter content of roots and shoots. Plants accumulated Na⁺ and the respective anions (chloride and sulfate) which in turn caused changes in the content of other nutrients. The content of potassium and calcium was decreased more than the other elements by both sodium salts. Sulfate salinity resulted in substantial increase in total sulfur and sulfate content but chloride salinity affected neither the total sulfur nor sulfate content of the roots and shoots, only in onion exposed to 200 mM chloride salt, those of roots and shoots were reduced. Furthermore, the water-soluble non-protein thiol content as well as the content of alliin remained rather unaffected. In conclusion, either salts affected the uptake and distribution of sulfate in onion, but had no or only a minor effect on the plant sulfur metabolism.