Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.     

Nutrient changes in direct-seeded submerged rice soils with varying nutrio-environments

Summary Nutrient changes in submerged rice soil were studied in soil-water-plant ecosystem in direct-seeded rice crop. Continuous removal of nutrients by the crop resulted in ultimate decrease in the availability of NH₄–N, P, K, Ca, Mg, Mn, Zn and Cu. However, there was a slight increase in Fe availability in soil with increase in period of submergence and crop growth. The data was subjected to statistical function fittings to study the nature of changes. Depending on the R²% values, quadratic type was the best fit for pH, available NH₄–N, K, Mg, Fe, Mn and Cu, whereas logarithmic type was the best fit for available P, Ca and Zn. No response was noticed to the application of P and K. Highest correlation coefficient between grain yield and NH₄–N in soil was obtained at the panicle initiation stage indicating that limiting nitrogen during this period might affect grain yield to the maximum extent compared to tiller initiation and maximum tillering stages.     

Influence of washing on elemental analysis of leaves of fieldgrown crop plants

Summary Information is limited on soil contamination of leaves from field-grown row crops, especially with respect to aluminum (Al) analyses. The objective of this study was to determine the influence of washing leaf samples with either deionized water or detergent solution on elemental analyses for several agronomic crop plants. The crop plants sampled were corn (Zea mays L.), soybean (Glycine max L. Merr.), grain sorghum (Sorghum bicolor L. Moench), and wheat (Triticum aestivum L.). The crops were grown on a range of soil types, soil pH values, and tillage practices. Samples of upper leaves and lower leaves were collected separately. The samples were either not washed, washed with deionized water, or washed with detergent solution. After drying, grinding, and digesting, the samples were analyzed for Al, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). For all crop plants and conditions studied, there was no effect on measured N, P, K, Ca, Mg, Mn, Zn, or Cu concentrations, but measured Al and Fe concentrations were influenced by washing. In general, washing had a greater effect on Al analyses than on Fe analyses. Soybean samples were most affected by washing, while wheat samples seemed to be least affected. The results reflected greater contamination of lower leaves than upper leaves. Decontamination procedures appear necessary prior to Al and Fe analyses of field-grown crop plants.     

Biomass and elemental uptake in fertilized and unfertilizedBetula papyrifera Marsh. andPopulus grandidentata Michx.

Summary Estimates were made of the above-ground biomass and contents of N, P, K, Ca, Mg, Mn, Na, Fe, Zn, Al, and Cu in fertilized (N 448 kg/ha, P 112 kg/ha, lime 4480 kg/ha) and unfertilized white birch (Betula papyrifera Marsh.) and bigtooth aspen (Populus grandidentata Michx.). For individuals of both species, fertilization increased the average above-ground biomass increment and the N and P content increment by 150 per cent and 300 per cent, respectively, but decreased uptake of Mn and Zn. The allocation of biomass and elements differs not only between species, but within species under untreated and fertilized conditions.     

The Rengen Grassland Experiment: relationship between soil and biomass chemical properties, amount of elements applied, and their uptake

The Rengen Grassland Experiment (RGE) was established in the Eifel Mountains (Germany) on a low productive Nardetum in 1941. Since then, the following fertilizer treatments have been applied with a late two-cut system: unfertilized control, Ca, CaN, CaNP, CaNPKCl and CaNPK₂SO₄. We aimed to understand how concentrations of macro (N, P, K, Ca and Mg), micro (Cu, Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were affected by long-term fertilizer application, soil chemical properties and biomass production. In 2008, biomass samples from the first cut (early July) and the second cut (mid-October) were collected and analyzed. The simultaneous application of N, P and K decreased nitrogen concentration in the aboveground biomass, but substantially increased biomass production. Late cutting management decreased forage quality in highly productive more than in low productive plant communities. The concentrations of P and K in the plant biomass were positively related to P and K application and, therefore, to plant available P and K concentrations in the soil. The concentrations of some micro (Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were negatively correlated with the amount of elements supplied by fertilizers and biomass production, probably because of the dilution effect. Long-term fertilizer application resulted in the accumulation of macro (P, Ca and Mg), micro (Fe and Mn) and trace (As and Cr) elements in the soil, but in many cases this accumulation was not connected with an increase in the concentrations of these elements in the plant biomass. Nutritional status, as indicated by the biomass N:P ratio, was consistent with N or P limitation as indicated by the nitrogen and phosphorus nutrition indices. Furthermore, additional K (co-)limitation was indicated by the N:K and K:P ratios in the biomass from the NP treatment. The results from the RGE indicate that there is no simple positive relationship between the applied elements and their concentrations in the plant biomass.     

Accumulation, Partitioning and Redistribution of Dry Matter and Mineral Nutrients in Ixia flexuosa L., with Special Reference to its Cormaceous Habit

The seasonal dynamics of uptake, partitioning and redistributionof dry matter, N, P, K, S, Ca, Mg, Na, Cl, Fe, Zn, Mn and Cuby the cormaceous plant Ixia flexuosa were studied in pot cultureat Perth, Western Australia. Dry matter and P, N, K, Zn andCu were redistributed from the mother corm with about 90 percent net efficiency: there was no net redistribution of Ca,Na, Fe or Mn. The efficiency of redistribution from the leafyshoot to fruits and the new season's corm was 80 per cent forN and P, 24–49 per cent for K, Cu and Zn, and 0–15per cent for Na, Fe, Ca, Mn, Cl, Mg, S and dry matter. Redistributionfrom the mother corm and vegetative organs could have suppliedthe replacement corm, cormlets and fruits with 32–53 percent of their S, K, P, N, Cu and Zn, and 11–25 per centof their Ca, Cl, Mn, Mg and dry matter. The mature replacementcorm had over 60 per cent of the plant's N and P, 25–50per cent of its dry matter, Zn, Cu, Mg, K and Cl, but less than20 per cent of its Ca, Na, Fe and Mn. Each plant produced anaverage of 12 cormlets; these had 35 per cent of the dry matterand 23–47 per cent of the amount of a particular nutrientin the new season's corms. Fruits had less than 16 per centof the dry matter and each mineral in the mature plant. Ratesof mineral intake by Ixia were much lower than reported forcrop plants, and may be related to the long growing season ofthe species. Ixia polystachya L., corm, nutrition, mineral nutrients, nutrient redistribution     

Biogeochemical consequences of the transformation of native Cerrado into Pinus caribaea plantations in Brazil

Under the same climatic and edaphic conditions, native savanna vegetation in Brazil, the Cerrado, shows a lower stature and canopy cover than planted Pinus caribaea Morelet forests. To assess the differences in biogeochemical element cycling we compared the nutrient economy of Cerrado and Pinus on three replicate plots of each forest type. The mean nutrient storage in the soil organic layer under Pinus (N: 2630; P: 141; K: 103; Ca: 131; Mg: 20 kg ha^–1) was substantially higher than under Cerrado (N: 23; P: 1.2; K: 0.83; Ca: 5.8; Mg: 1.0 kg ha^–1) probably because the Pinus roots explored a larger soil volume. The Pinus trees had a higher nutrient-use efficiency as indicated by higher mean litter mass per unit nutrient in litter (N: 108; P: 2290; K: 729; Ca: 1360; Mg: 5420; S: 1190; Fe: 2960; Mn: 9990, Zn: 145000) than the Cerrado trees (N: 94; P: 1810; K: 619; Ca: 302; Mg: 938, S: 746; Fe: 1800; Mn: 7880; Zn: 63700). Mean annual small litterfall collected in 0.25-m² samplers between May 1997 and April 1999 was 2.1 Mg ha^–1 in Cerrado and 7.8 in Pinus. The litterfall rates of the 1–3 week collection intervals correlated negatively with the soil matric potential indicating that litterfall was partly related to water stress. The fluxes of N (73 kg ha^–1 year^–1), P (3.7), K (11), S (7.0), and Mn (0.83) to the soil with litterfall under Pinus were greater than the litterfall+turnover of the grass/herbs layer under Cerrado (N: 39, P: 2.8, K: 8.6, S: 5.4, Mn: 0.79 kg ha^–1 year^–1), those of Zn (0.06–0.07) were similar, and those of Ca (Pinus: 5.9/Cerrado: 10), Mg (1.5/4.4), and Fe (2.9/4.0) were smaller. Mean residence times of the organic matter and of all elements were longer in the soil organic layer under Pinus (3.7–26 years in the Oi horizon, 8.1–907 years in the whole organic layer) than under Cerrado (0.22–3.6 years in the Oi horizon, the only organic horizon under Cerrado). Our results demonstrate that the main differences in biogeochemical element cycling between the Pinus forest and the Cerrado consisted of a larger nutrient storage in the organic layer, a higher nutrient-use efficiency, and slower nutrient release rates from the organic layer in the Pinus forest than in the Cerrado. Nutrient cycling as assessed by the nutrient fluxes with litterfall was only partly faster in the Pinus forest than in the Cerrado.     

Nutrient cycling and foliar status in an urban pine forest in Athens, Greece

The nutrient cycling and foliar status for the elements Ca, Mg, K, N, P, S, Fe, Mn, Zn and Cu were investigated in an urban forest of Aleppo pine (Pinus halepensis) in 2004 in Athens, Greece in order to draw conclusions on the productivity status and health of the ecosystem. The fluxes of bulk and throughfall deposition were characterized by the high amounts of Ca, organic N and sulfate S. The magnitude of the sulfate S fluxes indicated a polluted atmosphere. The nutrient enrichment in throughfall was appreciable for ammonium N, P and Mn. The mineral soil formed the largest pool for all the elements followed by the forest floor, trunk wood and trunk bark. The understory vegetation consisting of annual plants proved important for storing N, P and K. Compared to current year needles of Aleppo pine in remote forests of Spain, the needles of the Aleppo pine trees in Athens had significantly higher concentrations of Ca, N, P and Cu and significantly lower concentrations of Mg and Zn. The soil had a high concentration of calcium carbonate and accordingly high pH values. When all inputs to the forest floor were taken into account, the mean residence time of nutrients in the forest floor followed the order Fe > Mn > Cu > Ca > Mg > P > Zn > N > K > S.     

Contribution of mineral nutrients from source to sink organs in rice under different nitrogen fertilization

The pot experiment with three treatments of nitrogen (N) topdressing was performed with the japonica rice cultivar viz. Huaidao 5. Remobilization of nine mineral nutrients including N, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) was measured from the source organs including bracts, leaf, and sheath to sink rice grain. Experimental results showed considerable contribution of bracts to grain for N, Mg, and Zn, with the averages contributions of 5.96, 12.56, and 12.34%, respectively, indicating a positive role of rice bracts in N, Mg, and Zn remobilization during grain filling. By contrast, minor contribution of bracts to grain P, K, and Cu was revealed, with the contribution rate being 0.99, 3.90, and 3.05%, respectively. Further, a net increase in Ca and Fe concentrations of bracts was detected, implying that bracts function as a sink of these mineral nutrients. In addition, grains produced at a moderate level of N topdressing had higher Fe and similar Zn concentration in comparison with those at high N level, suggesting the possibility of N management for maintaining Fe and Zn level under high yielding conditions.     

镁肥对马尾松幼苗生长与叶片元素积累的影响

为了探讨上杭种源马尾松Pinus massoniana叶营养与生长对不同镁肥水平的响应,以其优良种源1年生苗为材料,设置4个镁肥梯度(42 g·m-2、85 g·m-2、170 g·m-2、339 g·m-2),测定移栽1年后苗木生长指标及叶内营养含量。结果表明,施镁能够促进元素P、K、Ca、Fe、Cu、Zn积累,抑制N、Mg、Mn积累;镁施肥量为85 g·m-2时,对N、Mg、Mn积累的抑制作用不显著,对P、K、Ca、Fe、Cu、Zn积累的促进作用最大,苗木生长最好,为最佳施肥量。施镁并不能促进苗木对镁的吸收,而是改变了营养供应的土壤环境,从而改变植物对其他营养的吸收比例,进而影响植物的生长。苗木的生长与Fe、P、K的关系最为密切,其次是Mg、Mn、Ca、N、Cu、Zn。     

中国南方生长于不同基质的天然林植物叶片元素含量特征比较

对比中国南方两个热带喀斯特森林、一个热带红树林和来自文献的一个亚热带常绿阔叶林植物叶片元素含量和计量特点。结果表明,受碳酸盐岩的影响,西双版纳和弄岗喀斯特森林植物叶片普遍富含Ca、Mg元素,因岩性差异,含有一定白云岩的弄岗地区的植物富集更多的Mg。西双版纳喀斯特森林存在K、Fe、Na、Zn元素的缺乏状况;由于白云岩矿物成分的特殊性和缓慢的风化速度,弄岗喀斯特植物有更高的叶片K、Zn、S含量。红树林植物富集P、Ca、Mg、Na、S元素,海水环境中大量的离子进入土壤被植物吸收利用,提高了红树的养分含量,并且在高盐环境下Na在叶片中大量富集。但是,红树植物表现缺乏Fe、Si、Zn。亚热带常绿阔叶林植物受酸性土影响大,Mn元素大量富集,P与Na的含量缺乏,并且相比其他生境,常绿阔叶林的N、P、Ca、Mg含量较低。西双版纳和弄岗的喀斯特森林植物叶片N/P比分别为14.27和18.26,说明前者受到N、P的共同限制,后者主要为P限制;红树植物N/P比为13.12,受N限制;常绿阔叶林植物本身严重缺P,N/P比为26.27,表现出明显的P限制。所研究的不同基质上的植物,叶片N与P元素之间均呈显著正相...     

秦岭产9种野菜中矿质元素含量的比较

野生蔬菜是指自然生长且未经人工栽培的蔬菜,因其富含人体所需的矿质元素、氨基酸及多种维生素而备受人们青睐[1-3],被公认为天然绿色食品.近年来,随生活水平的提高,多样化的饮食结构驱使人们不断对各种食品进行开发,尤其在旅游业的发展带动下,食用野菜已成为一种时尚和保健的需要.     

川东红池坝地区红三叶和鸭茅人工草地土壤和植物营养元素含量特征的研究

川东红池坝地区红三叶（Ｔｒｉｆｏｌｉｕｍｐｒａｔｅｎｓｅ）和鸭茅（Ｄａｃｔｙｌｉｓｇｌｏｍｅｒａｔａ）人工草地土壤和植物营养元素的含量特征如下：（１）土壤中的元素含量以铁、钾和镁较高,钠、钙、氮、锰和磷较低,硫、锌、硼、铜和钼微少;（２）从元素的富集特征来看,该区土壤中的钙、硫为重度淋溶元素,钾、磷、镁、锌、钠为中度淋溶元素,铁、铜属轻度淋溶元素,锰属富集元素;（３）根据元素的生物吸收系列,红三叶属氮－钙型植物,鸭茅属氮－钾－磷型植物。（４）两种牧草的生物吸收系数,均以钙、硫、磷较高,钠、铁较低,其余７种元素介于二者之间。     

Factors affecting tissue nutrient concentrations in aCarex meadow

Summary The influence of community and edaphic variables on tissue nutrient concentration was assessed for seven species on aCarex wetland in southern Quebec, Canada.Potassium and sodium tissue levels were considerably higher and Ca and Mg 35% lower than in a deciduous forest. Macronutrient concentrations decreased in the order K>N>Ca>Mg>Na>P. Micronutrient concentrations (Fe>Mn>Zn>Cu) ranged from 0.038–0.005 mg/g. This was 2–3 times less abundant than in an adjacentScirpus wetland. Inter-species coefficient of variation in N, P and K was low (14%) compared to variation in Ca, Mg, and the micronutrients (35%).Principal components analysis of interrelations between tissue elements indicated a clear distinction between N, P, K, Cu, Mn, and Zn levels and ash, Ca, Mg, Na, and Fe levels on the first component. This difference related closely to water depth and fire incidence. The coincidence of burning with water depth and the period of maximum snowmelt and runoff in the Spring suggested the loss of N, P, K, Cu, Mn and Zn by volotilization, runoff, or leaching.Stem density was the most important parameter influencing tissue N, P, and K concentrations whereas soil nitrogen levels were important in ash, Ca, and Mg concentrations. Water depth was the most important variable in the case of Cu, Fe, Mn, Na and Zn levels. Typha angustifolia had the highest level of total nutrients in green tissue,Carex lanuginosa the lowest. Principal components analysis indicated soil nitrogen, water depth, and soil potassium levels, in that order, were the three most important variables influencing the patterns of tissue element variation among species.Potassium and sodium levels in 1-year old litter were 11% and 0.4% compared to concentrations in green tissue. Iron and manganese, both subject to oxidation and adsorption to litter at the soil surface, were distinctly higher (2247% and 199%) in litter than green tissue. Concentrations of these and other elements in litter were consistent with results reported in literature and indicated litter was especially active as a site of cation exchange in the system.     

Seasonal Dynamics of the Accumulation, Distribution and Redistribution of Dry Matter and Mineral Nutrients in a Weedy Species of Gladiolus (Gladiolus caryophyllaceus)

The seasonal dynamics of the accumulation, distribution andredistribution of dry matter and 12 mineral nutrients by a weedyspecies of gladiolus (Gladiolus caryophyllaceus) were studiedat Perth, Western Australia, where it has colonized the nutrient-poorsandy soils. Parent corms sprouted in autumn, and the plantshad completed their growth cycle by early summer. The maturereplacement corm had 15-25% of the plant's P, Ca, Na, Zn andCu, 5-15% of its K, N, Cl, Mg, S and dry matter, and < 5%of its Fe and Mn. Seeds had 26% of the plant's dry matter, 60%of its N and P, 21-33% of its S, Mg, Cu and K, 5-20% of itsFe, Mn and Zn, and < 5% of its Ca and Na. The mature vegetativeshoot had 47% of the plant's dry matter and over 40% of eachnutrient, except for N, P and Cu. Phosphorus, K and N were redistributedfrom the parent corm with over 85% efficiency, S, Mg, Zn andCu with 60-70% efficiency, but there was < 10% redistributionof Ca, Na, Cl, Fe and Mn. The efficiency of redistribution fromthe leafy shoot was over 70% for N and P, 29-52% for K, Mg andCu, 16-20% for S, Zn and Cl, but negligible for Ca, Na, Fe andMn. Redistribution from the shoot could have provided the replacementcorm and seeds with 53-98% of their Cu, Mg, N, P and K, and29-38% of their S, Zn and dry matter. Seeds contained over 60%of each nutrient in a capsule, except for Ca, Na and Fe. Redistributionfrom the capsule walls could have provided 13-19% of the P,Cu and Zn, and 3-7% of the N, K, Mg and dry matter accumulatedby seeds. Each plant produced an average of 520 seeds. Removalof flowers and buds at first anthesis resulted in a larger replacementcorm containing a greater quantity of most nutrients, indicatingcompetition between the replacement corm and seeds for nutrients.Redistribution from parent to replacement cormlets in the absenceof shoot and root development was high, with over 50% of thedry matter and each nutrient, except for Ca, being transferred.Concentration of nutrients were low in all organs of G. caryophyllaceus,especially the replacement corm. It was concluded that the effectiveredistribution of key nutrients, such as N and P, to reproductivestructures and tolerance of low internal concentrations of nutrientscontribute to the capacity of G. caryophyllaceus to colonizeand persist on infertile soils.Copyright 1993, 1999 AcademicPress Gladiolus caryophyllaceus, corm, distribution, dry matter, gladiolus, mineral nutrients, nutrient accumulation, nutrient redistribution, seasonal growth, weed     

Regulation of Mineral Redistribution in Pod-Bearing Soybean Explants

On the way from the roots to the seeds during reproductive developmentin soybean (Glycine max), a large proportion of the mineralspass through the leaves rather than travelling directly viathe xylem. This direct and indirect movement of mineral nutrientshas important implications for mineral redistribution, seeddevelopment and leaf senescence. Therefore, we have studiedthe role of cytokinin and mineral flux from the roots in regulatingmineral redistribution from the leaves to the seeds using explants,i.e. a leaf, a pod and a subtending stem segment, with theirbases immersed in treatment solutions. Thus, defined solutionscontaining cytokinin and/or minerals can be substituted forthe roots. When explants (excised at early-mid podfill) aresupplied H₂O only, leaf N, P, K, Mo, Mg, Zn, Fe, B, Cu, Ca,and Mn decline, ranging from 93% for Mo to 38% for Fe. In explantson H₂O, N, P, K, Mo, Mg, Zn, and Fe appear to be redistributedfrom the leaves to the seeds, while the B, Cu, Ca, and Mn lostfrom the leaves do not seem to move to the seeds. Although amixture of minerals resembling xylem sap can delay net lossof these elements from the leaves, it does not prevent the decreases.The cytokinin zeatin (4.6 µM) inhibits the loss of N,IC, Mo, Mg, Zn, Fe, B, Cu, Ca, and Mn from the leaves, but notthat of P. When combined with minerals, zeatin not only preventsthe loss of the minerals from the leaves but may even greatlyincrease them with the possible exception of Zn, Fe, and Cu.Supplying the mineral nutrient mixture increases the quantitiesof N, P, K, Mg, Cu, and B in the seeds but not Zn, Fe, Mn, Ca,and Mo. For those minerals, especially N, where zeatin inhibitsefflux from the leaves, it may reduce the amounts in the seeds,but it does not change P, K, Mg, and Ca. The accumulation andredistribution patterns of the different mineral nutrients showmany dissimilarities thereby suggesting differences in the controlof their distribution. Key words: Cytokinin, mineral transport, seed development, senescence     

氮素营养对苗期菘蓝叶中硝酸还原酶活性与矿质元素吸收的影响

采用正交试验设计,研究铵态氮、硝态氮和酰胺态氮3种氮素形态及其不同浓度配比对苗期菘蓝的单株干重、叶内的硝酸还原酶活性及矿质元素吸收的影响。结果显示:(1)影响苗期菘蓝单株干重的氮素形态依次为酰胺态氮>铵态氮>硝态氮。(2)不同氮素形态对叶片硝酸还原酶活性影响有差异,铵态氮影响最大,其次是硝态氮和酰胺态氮。(3)不同形态氮素配合施用后均能促进P、K、Ca、Mg、Cd、Mn、Cr、Sr 8种元素的吸收,但不利于Ni和Fe的吸收;元素吸收受铵态氮影响最大的矿质元素有K、Ba、Se、Ni、B、Si、Fe 7种元素,受硝态氮影响最大的元素有P、Cd、Ti、Al、Cu 5种元素,受酰胺态氮影响最大的元素有Na、Ca、Mg、Zn、Mo、Mn、Cr、Sr 8种元素。研究表明,不同形态氮素对苗期菘蓝吸收矿质元素的影响存在很大的差异,应注重酰胺态氮与无机的铵态氮、硝态氮的配合施用;适宜氮素形态及其配比能提高叶中硝酸还原酶的活性并促进矿质元素的吸收,从而有效地促进菘蓝的生长。     

Concentrations and resorption patterns of 13 nutrients in different plant functional types in the karst region of south-western China

Background and Aims

Elucidating the stoichiometry and resorption patterns of multiple nutrients is an essential requirement for a holistic understanding of plant nutrition and biogeochemical cycling. However, most studies have focused on nitrogen (N) and phosphorus (P), and largely ignored other nutrients. The current study aimed to determine relationships between resorption patterns and leaf nutrient status for 13 nutrient elements in a karst vegetation region.

Methods

Plant and soil samples were collected from four vegetation types in the karst region of south-western China and divided into eight plant functional types. Samples of newly expanded and recently senesced leaves were analysed to determine concentrations of boron (B), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), N, sodium (Na), P, sulphur (S) and zinc (Zn).

Key Results

Nutrient concentrations of the karst plants were lower than those normally found in other regions of China and the rest of the world, and plant growth was mainly limited by P. Overall, four nutrients revealed resorption [N (resorption efficiency 34·6 %), P (48·4 %), K (63·2 %) and Mg (13·2 %)], seven nutrients [B (–16·1 %), Ca (–44·0 %), Cu (–14·5 %), Fe (–205·5 %), Mn (–72·5 %), Mo (–35·6 %) and Zn (–184·3 %)] showed accumulation in senesced leaves and two nutrients (Na and S) showed no resorption or accumulation. Resorption efficiencies of K and Mg and accumulation of B, Ca, Fe and Mn differed among plant functional types, and this strongly affected litter quality. Resorption efficiencies of N, P and K and accumulation of Ca and Zn increased with decreasing concentrations of these nutrients in green leaves. The N:P, N:K and N:Mg ratios in green leaves predicted resorption proficiency for N, K and Mg, respectively.

Conclusions

The results emphasize the fact that nutrient resorption patterns strongly depend on element and plant functional type, which provides new insights into plant nutrient use strategies and nutrient cycling in karst ecosystems.     

Resorptions of 10 mineral elements in leaves of desert shrubs and their contrasting responses to aridity

Aims We aim to investigate variations in the resorption efficiencies of 10 mineral nutrients [i.e. nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), zinc (Zn), aluminum (Al), iron (Fe) and copper (Cu)] in leaves of desert shrubs and to explore effects of aridity on resorption efficiency of these nutrients.     

Arbuscular mycorrhizas enhance nutrient uptake in different wheat genotypes at high salinity levels under field and greenhouse conditions

Since most experiments regarding the symbiosis between arbuscular mycorrhizal (AM) fungi and their host plants under salinity stress have been performed only under greenhouse conditions, this research work was also conducted under field conditions. The effects of three AM species including Glomus mosseae, G.?etunicatum and G.?intraradices on the nutrient uptake of different wheat cultivars (including Roshan, Kavir and Tabasi) under field and greenhouse (including Chamran and Line 9) conditions were determined. At field harvest, the concentrations of N, Ca, Mg, Fe, Cu, and Mn, and at greenhouse harvest, plant growth, root colonization and concentrations of different nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl were determined. The effects of wheat cultivars on the concentrations of N, Ca, and Mn, and of all nutrients were significant at field and greenhouse conditions, respectively. In both experiments, AM fungi significantly enhanced the concentrations of all nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl. The synergistic and enhancing effects of co-inoculation of AM species on plant growth and the inhibiting effect of AM species on Na(+) rather than on Cl(-) uptake under salinity are also among the important findings of this research work.