Nutrient Uptake

Spatial patterning of ecosystems can be explained by several mechanisms. One approach to disentangling the influence of these mechanisms is to study a patterned ecosystem along a gradient of environmental conditions. This study focused on hummock-hollow patterning of peatlands. Previous models predicted that patterning in drainage-dominated peatlands is driven by a peat-accumulation mechanism, reflected by higher nutrient availability in hollows relative to hummocks. Alternatively, patterning in evapotranspiration (ET)-dominated peatlands may be driven by a nutrient-accumulation mechanism, reflected by reversed nutrient distribution, namely, higher nutrient availability in hummocks relative to hollows. Here, we tested these predictions by comparing nutrient distributions among patterned peatlands in maritime (Scotland), humid temperate (Sweden), and humid continental (Siberia) climates. The areas comprise a climatic gradient from very wet and drainage-dominated (Scotland) to less wet and ET-dominated (Siberia) peatlands. Nutrient distribution was quantified as resource contrast, a measure for hummock-hollow difference in nutrient availability. We tested the hypothesis that the climatic gradient shows a trend in the resource contrast; from negative (highest nutrient availability in hollows) in Scotland to positive (highest nutrient availability in hummocks) in Siberia. The resource contrasts as measured in vegetation indeed showed a trend along the climatic gradient: contrasts were negative to slightly positive in Scotland, positive in Sweden, and strongly positive in Siberia. This finding corroborates the main prediction of previous models. Our results, however, also provided indications for further model development. The low concentrations of nutrients in the water suggest that existing models could be improved by considering both the dissolved and adsorbed phase and explicit inclusion of both nutrient-uptake and nutrient-storage processes. Our study suggests that future climate change may affect the ecosystem functioning of patterned peatlands by altering the contribution of pattern-forming mechanisms to redistribution of water and nutrients within these systems.

While non-point nutrient loads are important determinants of biological productivity in Southeastern Piedmont impoundments, productivity can be attenuated by concomitant sediment loads that reduce the biological availability of these nutrients. A biogeochemical model is proposed ...

Soilless plant growth systems are widely used as a means to save irrigation water and to reduce groundwater contamination. While nutrient concentrations in the growth medium are depleted due to uptake by the plants, salinity and toxic substances accumulate due to transpiration. A theoretical model is suggested, to simulate nutrient uptake by plants grown in soilless cultures with recycled solutions. The model accounts for salinity accumulation with time and plant growth, and its effects on uptake of the different nutrients by means of interaction with Na and Cl ions. The sink term occurs due to uptake by a growing root system. Influx as a function of the ion concentration is according to Michaelis-Menten active mechanisms for K + , NO 3 − -N, NH 4 + -N, PO 4 -P, Ca 2+ , Mg 2+ and SO 4 2− , whose influx parameters are affected by Na and Cl − , but not with time (age). Sodium influx is passive above a critical concentration. Sum of cations-anions concentrations is balanced by Cl − to maintain electro-neutrality of the growth solution. Salinity (by means of Na concentration) suppresses root and leaf growth, which further effect uptake and transpiration. The model accounts for instantaneous transpiration losses, during daytime only and its effect on uptake of nutrients and plant development due to salt accumulation. The model was tested against NO 3 − and K + uptake by plants associated with cumulative transpiration and with different NaCl salinity levels. Deviations from observed K + uptake should be attributed to the salinity tolerance of the plants. In a study with data obtained from published literature, the model indicated that nutrient depletion and salinity buildup might be completely different with fully grown-up plants (that do not grow) and plants that grow with time. Depletion of different nutrients are according to their initial concentration and plant uptake rate, but also affected by their interactions with Na and Cl ions.

Information concerning the sugar status of plant cells is of greatimportance during all stages of the plant life cycle. The aim of this work wasto study primary carbohydrate metabolism in hairy roots of red beet. Growth ofhairy roots of red beet in vitro and changes in concentration of major nutrientsand sugar in the media were measured over a growth cycle

Trade-offs between acquisition capacities for aboveground and belowground resources were investigated by studying the phenotypic plasticity of leaf and root traits in response to different irradiance levels at low nutrient supply. Two congeneric grasses with contrasting light requirements, Dactylis glomerata and D. polygama, were used. The aim was to analyze phenotypic covariation in components of leaf area and root length in response to above-and belowground resource limitation and the consequences of this variation for resource acquisition and plant growth. At intermediate shading (30 and 20% of full sunlight) the plants were able to maintain their total root length, despite a strongly increased total leaf area and a reduced biomass allocation to roots. This was associated with an unaltered or slightly increased nutrient uptake and growth. At 5.5% relative irradiance, growth was severely reduced, especially in the shade-tolerant D. polygama. The results show that constraints on acquisition capacities for aboveground and belowground resources, caused by biomass allocation, may be alleviated by plasticity in other traits such as tissue-mass density and thickness of roots and leaves. The results also suggest different adaptive constraints for phenotypic plasticity and for genetically determined interspecific variation. Phenotypic plasticity tends to maximize resource acquisition and growth rate in the short term, whereas the higher tissue-mass density and the longer leaf life-span of shade-tolerant species indicate reduced loss rates as a more advantageous speciesspecific adaptation to shade in the long term.

The present study was conducted to assess the plant growth promoting activities of Mesorhizobium sp. in the presence of technical grade herbicides and its ameliorating effects on herbicide toxicity to chickpea grown in herbicide treated soils. The quizalafop-p-ethyl and clodinafop-tolerant Mesorhizobium isolate MRC4 recovered from the nodules of chickpea plants significantly produced IAA, siderophores, hydrogen cyanide and ammonia in medium amended with or without technical grade quizalafop-p-ethyl and clodinafop. Quizalafop-p-ethyl at 40, 80 and 120 lg kg À1 soil and clodinafop at 400, 800 and 1200 lg kg À1 soil in general, decreased the growth attributes of chickpea plants inoculated with Mesorhizobium MRC4 and un-inoculated chickpeas. The three concentrations of quizalafop-p-ethyl were comparatively more toxic and substantially decreased biomass, nodulation and leghaemoglobin content, nutrient uptake, seed yield and grain protein over the un-inoculated chickpea. Interestingly, Mesorhizobium isolate MRC4 with any concentration of the two herbicides significantly increased the measured parameters when compared to the plants grown in soils treated solely (without inoculant) with similar concentration of each herbicide. Conclusively, Mesorhizobium isolate MRC4 could be exploited as bio-inoculant for facilitating chickpea growth under herbicide stress.

Our study provides information on the relationships between physical, chemical, and biological properties of East Antarctic sea ice sampled as part of the Sea Ice Physics and Ecosystem eXperiment (SIPEX) during the winter-spring transition in 2007. The sampled sea ice showed a high contribution of granular ice, indicating the turbulent conditions during sea ice formation off East Antarctica. The sea ice was cold, with brine volumes often below or very close to the theoretical percolation threshold of sea ice. Dissolved inorganic nutrient concentrations showed both positive and negative deviations from theoretical dilution lines, indicating both nutrient uptake as well as nutrient remineralisation in sea ice brines. Cold temperatures, high brine salinities, and low brine volumes limited high ice algal biomass to the warmer and more porous sea ice layers at the ice-water interface. We hypothesise that East Antarctic sea ice shows generally low ice algal biomass accumulation due to a combination of relatively low snow-loading, relatively cold ice temperatures, and short persistence of sea ice into the warm forcing regime, all of which prevent the development of significant internal and surface communities.

Lebanon's native flora is threatened by loss of natural habitat to rural and urban development and the increased demand of plant materials for landscaping. Despite Lebanon's floristic richness, most taxa used for landscaping are non-native. This study was done to determine if Cercis siliquastrum (L.) is amenable to container production. Therefore, six open pollinated seeds sources native to Lebanon were grown under two fertilizer rates to study growth, N, P, K uptake efficiency, and partitioning. Two-year-old seedlings were planted in 11 L containers in a 3:1 pine bark:compost substrate. Seedlings within each seed source or mother tree were grown at either 25 or 100 mg N L À1 from 21N-3.1P-5.9K watersoluble fertilizer. Seedlings of all sources grown under 25 mg N L À1 had greater dry weight than those grown at 100 mg. Nutrient loading occurred in plants under the high fertilizer rate, although total plant N, P, and K content were not affected by fertilizer rate. There were significant differences in mineral nutrient uptake and nutrient use efficiencies among the seed sources. The results show that C. siliquastrum is amenable to container production. The great variation in growth rate and nutrient use efficiency among the limited number of seed sources studied suggest that significant improvement can be made through mother tree selection and/or clonal propagation of superior individual plants within a source. #

of phytoplankton growth dynamics and nutrient assimilation by a computer simulation model are consistent with studies of field and laboratory populations. The model simulates population dynamics and gross physiology of phytoplankton species in

In tropical acid soils, acidity is an important constraint for availability and uptake of nutrients by annual crops, and this leads to lower crop yields. Factors that contribute to low nutrient uptake efficiencies in these soils are low natural levels of most essential plant nutrients and unfavorable soil and plant environments. High P fixation capacity, Al, Mn and H toxicity,

Artemisia annua L. (Asteraceae) is an important medicinal plant whose secondary metabolite artemisinin is used for the treatment of cerebral malaria. A study was undertaken to determine the effect of arbuscular mycorrhizal (AM) fungi, Glomus mosseae, Glomus aggregatum, Glomus fasciculatum, Glomus intraradices and two free living nitrogen fixing bacteria (NFB) (identified as Bacillus subtilis and Stenotrophomonas spp. through 16S rRNA gene sequence analysis), inoculated alone or in combinations on the biomass, nutrient uptake, and content of artemisinin in A. annua under glass house conditions. Various parameters like plant height, total plant biomass, NPK content, leaf yield, mycorrhizal colonization, bacterial population in rhizosphere, phosphatase activity and artemisinin content were determined and found to vary with different treatments. Among all the treatments, plants inoculated with G. mosseae + B. subtilis performed better than any other treatment or uninoculated control plants. The results of the experiment clearly indicated the compatibility and synergy between G. mosseae and B. subtilis and suggested the use of this microbial consortium in A. annua for enhancing growth, biomass yield, and the content and yield of artemisinin.

Carnivorous plants may benefit from animal-derived nutrients to supplement minerals from the soil. Therefore, the role and importance of their roots is a matter of debate. Aquatic carnivorous species lack roots completely, and many hygrophytic and epiphytic carnivorous species only have a weakly developed root system. In xerophytes, however, large, extended and/or deep-reaching roots and sub-soil shoots develop. Roots develop also in carnivorous plants in other habitats that are hostile, due to flooding, salinity or heavy metal occurance. Information about the structure and functioning of roots of carnivorous plants is limited, but this knowledge is essential for a sound understanding of the plants’ physiology and ecology. Here we compile and summarise available information on: The morphology of the roots. The root functions that are taken over by stems and leaves in species without roots or with poorly developed root systems; anchoring and storage occur by specialized chlorophyll-less stems; water and nutrients are taken up by the trap leaves. The contribution of the roots to the nutrient supply of the plants; this varies considerably amongst the few investigated species. We compare nutrient uptake by the roots with the acquisition of nutrients via the traps. The ability of the roots of some carnivorous species to tolerate stressful conditions in their habitats; e.g., lack of oxygen, saline conditions, heavy metals in the soil, heat during bushfires, drought, and flooding.kg]Key words

Models are needed for forecasting the effects of eutrophication on stream and river ecosystems. Most of the current models do not include differences in local stream characteristics and effects on the biota. To define the most important variables that should be used in a stream eutrophication model, the literature was reviewed.

____________________________________________________________________________________________________________________________________________________________________________ Chopart JL, Sine B, Dao A, Muller B 2008. Root orientation of four sorghum cultivars: application to estimate root length density from root counts in soil profiles. Plant Root 2: 67-75. doi:10.3117/plantroot.2.67 Copyrights 2008, Plant Root (JSRR), www.plantroot.org O Or ri ig gi in na al l r re es se ea ar rc ch h a ar rt ti ic cl le e Abstract:

Trait-based approaches to community structure are increasingly used in terrestrial ecology. We show that such an approach, augmented by a mechanistic analysis of tradeoffs among functional traits, can be successfully used to explain community composition of marine phytoplankton along environmental gradients. Our analysis of literature on major functional traits in phytoplankton, such as parameters of nutrient-dependent growth and uptake, reveals physiological trade-offs in species abilities to acquire and utilize resources. These trade-offs, arising from fundamental relations such as cellular scaling laws and enzyme kinetics, define contrasting ecological strategies of nutrient acquisition. Major groups of marine eukaryotic phytoplankton have adopted distinct strategies with associated traits. These diverse strategies of nutrient utilization can explain the distribution patterns of major functional groups and size classes along nutrient availability gradients.

In this study, water and nutrient uptake from the substrate and responses of the crop to fertigation strategies were analysed. In an experiment and simulation study, the amount and frequency of fertigation and electrical conductivity (EC) of the fertigation water were changed for a tomato crop grown on rockwool. In a climate chamber, tomato plants were grown on rockwool while five different EC levels and two fertigation frequencies were maintained. Effects on plant growth, water uptake, and nutrient uptake were measured. The experimental data were compared with simulated results. We used two simulation models: a plant growth model and a model that describes water movement and nutrient transport within the substrate, i.e. rockwool, and root uptake of water and nutrients from the substrate.

A tomato (Solanum lycopersicum L.) crop was grown in four greenhouses during the dry season 2005/06 in Central Thailand. Sidewalls and roof vents of two greenhouses were covered with nets and these greenhouses were mechanically ventilated when air temperature exceeded 30 8C (NET). The other two greenhouses were covered with polyethylene film and equipped with a fan and pad cooling system (EVAP). Overall mean air temperature was significantly reduced by 2.6 and 3.2 8C (day) and 1.2 and 2.3 8C (night) in EVAP as compared to NET and outside air, respectively. Temperature maxima in EVAP averaged about 4 8C lower than in NET and outside. The relative humidity was around 20 and 30% (day) and 10 and 15% (night) higher in EVAP than in NET or outside, respectively. Vapour pressure deficit averaged 0.25 kPa in EVAP, 1.03 kPa in NET and 1.48 kPa outside. The crop water-consumption was significantly lower in EVAP (1.2) than in NET (1.8 L plant À1 day À1), which is ascribed to reduced transpiration in EVAP. Total fruit yield was similar in NET (6.4 kg plant À1) and EVAP (6.3 kg plant À1). The quantity of undersized (mostly parthenocarpic) and blossom-end rot (BER)-affected fruits was reduced in EVAP. However, the proportion of marketable yield was significantly higher in NET (4.5 kg plant À1) than in EVAP (3.8 kg plant À1), owing largely to an increased incidence of fruit cracking (FC) in EVAP. Higher FC but lower BER incidence coincided with higher fresh weight and Ca concentration in the fruits in EVAP. It is concluded that in regions with high atmospheric relative humidity evaporative cooling without technical modifications allowing dehumidification will not improve protected tomato production.

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.

To enhance the fertilizer value of rock phosphate in alkaline soils, the phosphate (P) solubilizing fungus Penicillium oxalicum was isolated from the rhizosphere soil of rock phosphate mine landfills and tested for its efficacy to solubilize rock phosphate (RP) as well as promotion of the growth of wheat and maize plants grown in soil amended with RP. The results showed that P. oxalicum effectively solubilized RP in Pikovskaya's medium and released higher amount of phosphorus. The solubilization was increased with increase in concentration of RP. Field experiments showed that inoculation of P. oxalicum significantly increased the growth and yield of two consecutive crops i.e. wheat and maize compared to the control soil. The P content was significantly increased in the plants. The available P and organic carbon levels increased in RP amended soil inoculated with P. oxalicum compared to the control soil. It was found that the P. oxalicum along with RP can substitute the chemical fertilizer in alkaline soil and help in improving the crop production.

SUMMARYAn on-farm trial was conducted in the northern Guinea savanna of Nigeria, over a period of five years, with the objectives of quantifying the effects on maize of applying cattle manure in combination with synthetic fertilizer with regard to soil characteristics, yield, plant nutrition and profitability. Maize grain yield was significantly increased by the annual application of cattle manure, compared to maize receiving an equal amount of N through synthetic fertilizer, but only from the third year of the experiment. The application of manure resulted in higher soil Kjel N, Bray-I P and exchangeable K values, and an increased N utilization efficiency by maize, suggesting that yield-limiting factors other than N deficiencies were of lesser importance than in the treatment receiving sole inorganic fertilizer. Nutrients other than N applied via the manure, particularly P, K and/or B, may have contributed to the higher grain yields in treatments receiving manure. A partial budgeti...

A field experiment was conducted to study the effect of vermicompost and three different levels of phosphorus fertilization on nutrient uptake in grain, straw, their total uptake and yield in mung bean at wheat program research area NARC, Islamabad. Application of phosphorus and vermicompost plays an important role in growth, development and maturity of crop and also in development of roots and nodulation. The soil was low in organic matter (0.8%), available nitrogen (1.76mg kg -1 ), phosphorus (2.9mg kg -1 ) and medium in available potassium (120mg kg -1 ). Application of vermicompost (2 t ha -1 ) with full dose of phosphorus (75 kg P 2 O 5 ha -1 ) treatment (V1P2) fertilization markedly influenced the nutrient concentration in grains (2.56% of N, 0.3% of P, 1.23% of K), their uptake (62 kg ha -1 N, 12 kg ha -1 P, 39 kg ha -1 K) and yield (1410 kg ha -1 ) over control in mung bean. Economically significant nutrient contents in grain (2.44% N, 0.37% P, 1.17% K), nutrient uptake (52 ...

Nutrient uptake Weathering a b s t r a c t Fungi are agents of geochemical change in the environment and play important roles in the soil, the plant-root zone, and in rock and mineral habitats. Modelling may serve as a tool to quantify fungal weathering under natural conditions. This paper provides a review of existing mycelial growth models and examines how these can be adapted to describe weathering by ectomycorrhizal and other fungi in mineral soil.

The banana weevil Cosmopolites sordidus (Germar) is the most important insect pest of bananas and plantains (Musa spp.). The larvae bore in the corm, reducing nutrient uptake and weakening the stability of the plant. Attack in newly planted banana stands can lead to crop failure. In established fields, weevil damage can result in reduced bunch weights, mat die-out and shortened stand life. Damage and yield losses tend to increase with time. This paper reviews the research on the taxonomy, distribution, biology, pest status, sampling methods, and integrated pest management (IPM) of banana weevil. Salient features of the weevil's biology include nocturnal activity, long life span, limited mobility, low fecundity, and slow population growth. The adults are free living and most often associated with banana mats and cut residues. They are attracted to their hosts by volatiles, especially following damage to the plant corm. Males produce an aggregation pheromone that is attractive to both sexes. Eggs are laid in the corm or lower pseudostem. The immature stages are all passed within the host plant, mostly in the corm. The weevil's biology creates sampling problems and makes its control difficult. Most commonly, weevils are monitored by trapping adults, mark and recapture methods and damage assessment to harvested or dead plants. Weevil pest status and control options reflect the type of banana being grown and the production system. Plantains and highland bananas are more susceptible to the weevil than dessert or brewing bananas. Banana production systems range from kitchen gardens and small, low-input stands to large-scale export plantations. IPM options for banana weevils include habitat management (cultural controls), biological control, host plant resistance, botanicals, and (in some cases) chemical control. Cultural controls have been widely recommended but data demonstrating their efficacy are limited. The most important are clean planting material in new stands, crop sanitation (especially destruction of residues), agronomic methods to improve plant vigour and tolerance to weevil attack and, possibly, trapping. Tissue culture plantlets, where available, assure the farmer with weevil-free material. Suckers may be cleaned by paring, hot water treatment and/or the applications of entomopathogens, neem, or pesticides. None of these methods assure elimination of weevils. Adult weevils may also invade from nearby plantations. As a result, the benefits of clean planting material may be limited to a few crop cycles. Field surveys suggest that reduced weevil populations may be associated with high levels of crop sanitation, yet definitive studies on residue management and weevil pest status are wanting. Trapping of adult weevils with pseudostem or corm traps can reduce weevil populations, but material and labour requirements may be beyond the resources of many farmers. The use of enhanced trapping with pheromones and kairomones is currently under study. A combination of clean planting material, sanitation, and trapping is likely to provide at least partial control of banana weevil. Classical biological control of banana weevil, using natural enemies from Asia, has so far been unsuccessful. Most known arthropod natural enemies are opportunistic, generalist predators with limited efficacy. Myrmicine ants have been reported to help control the weevil in Cuba, but their effects elsewhere are unknown. Microbial control, using entomopathogenic fungi and nematodes tend to be more promising. Effective strains of microbial agents are known but economic mass production and delivery systems need further development.

An experiment was conducted at the Asian Institute of Technology, Thailand, for 54 days to investigate on the effect of pond water filtration and aggregates (hydroponic substrates) on lettuce (Lactuca sativa L.) production, nutrient uptake and growth. A 2 × 3 factorial experiment consisting of 2 filtration regimes (unfiltered versus partially filtered pond water) and 3 aggregates (styrofoam as control, sand, and gravel). The hydroponic units were placed on a bamboo platform across the pond surface. An earthen pond (226 m 2 ) was stocked with 8000 hybrid catfish with an average initial weight of 6.58 ± 1.72 g. The fish were fed with commercial pelleted feeds containing 30% crude protein. Twenty-one days old lettuce seedlings were transplanted on to hydroponic units after stocking catfish for 4 months in the pond. Pond water was partially filtered by using a settling tank and filtration tank, which contained netting materials to trap solids. Lettuce plots were irrigated twice daily at 0800 and 1600 h using either filtered or unfiltered pond water for 45 min.

Allocation of above and below-ground growth and nutrient uptake, and pollutant removal were compared for Schoenoplectus t, alidus, Phragmites australis, Glyceria maxima, Baumea articulata, Bolboschoenus fluviatilis, Cyperus involucratus, Juncus effusus and Zizania latifolia. Plants were grown in triplicate 0.238 m2× 0.6 m deep gravel-bed wetland mesocosms fed with dairy farm wastewaters pre-treated in an anaerobic lagoon. After 124 days, mean species total biomass ranged from 0.3 to 7.4 kg m -2 with above-below-ground ratios between 0.35 and 3.35. Growth of Baumea and Juncus was relatively poor. Zizania and Glyceria showed the highest above-ground biomass values, ranging between 3 and 4 kg m-2. Above-ground tissue concentrations of nitrogen (N) and phosphorus (P) ranged from 15 to 32 and 1.3 to 3.4 mg g-i, respectively. Maximum plant accumulations of 135 g N m -2 and 18.5 g P m -2 accounted for around 30% of the levels supplied in wastewaters. Mean removals of 76-88% of suspended solids, 77-91% of biochemical oxygen demand, and 79-93% of total P were recorded for the established mesocosms irrespective of plant species. Mean removal of total N ranged from 65 to 92%, showing a significant positive linear correlation with plant biomass. Comparisons are made with information from other studies on establishment rate, productivity, nutrient uptake, potential for root-zone aeration and general life history traits in constructed wetlands.

The availability of nitrogen in sediment phytodetritus to seagrass was investigated in 5 tropical species (Thalassia hemprichii, Halodule uninervis, H, pinifolia, Halophila ovalis/ovata and Syringodium isoetifolium) from Indonesia. N-15-labeled phytodetritus was injected into the sediment and the appearance of N-15 in the roots, the rhizomes and the leaves of the plants were measured after 1, 2, 4 and 8 d. The transfer of N-15 from sediment phytodetritus to the plant tissues was very rapid (within 1 d) and continued over the 8 d period, indicating an efficient retention of the phytodetritus and a net mineralization of nitrogen rather than an immobilisation by bacteria. Relative enrichment of roots versus leaves indicated that N-15 was taken up by the roots and then transferred to the leaves. The combined efficiency of seagrass canopy-induced trapping and retention of sestonic particles and root-uptake, results in the acquisition of nutrients released upon mineralization of particula...

Indigenous arbuscular mycorrhizae Fungi (AMF) have a potential to boost maize (Zea mays) growth and increase the P and Zn uptake through the symbiotic association they form with the plant, even in acidic soils conditions. Five AMF inoculums produced from the most abundant and ubiquitous morphotypes isolated from field soils in maize fields in South Kivu (DRC) were assessed. A greenhouse experiment was conducted to determine the role of these AMF on nutrients uptake in a Nitisol and a Ferralsol. Eight treatments namely inoculums named AMF1 (Gigaspora gigantea), AMF2 (Gigaspora sp.), AMF3 (Gigaspora margarita), AMF4 (Rhizophagus intraradices) AMF5 (Acaulospora reducta), mineral phosphorus fertilizers (Pi), commercial biofertilizer Rhizatech and a Control were laid in a randomized complete block design. In the Ferralsol, Pi application, Rhizatech and AMF2 produced the highest height. Pi application resulted in the best shoot biomass. No difference was observed for the P content, but for the Zn content, AMF2 was the highest. Roots colonization did not vary among treatments. In the Nitisol, AMF4 produced the highest plant height and AMF1 the highiest chlorophyll content. AMF4 and Rhizatech colonized highly the roots. AMF3 gave the highest P however, Zinc content was equal in all treatments and the controls yielded the lowest results. Spores densities in both inoculums produced and experimental soils were low compared to the commercial inoculum but growth and roots colonisation was influenced by fertilization and soils types. The performance of efficient AMF inoculums of Gipaspora gigantea, Gigaspora sp., Rhizophagus intraradices and Acaulospora reducta applied with high densities spores and multispecies inoculums should be assessed.

A field experiment was conducted to study the effect of vermicompost and three different levels of phosphorus fertilization on nutrient uptake in grain, straw, their total uptake and yield in mung bean at wheat program research area NARC, Islamabad. Application of phosphorus and vermicompost plays an important role in growth, development and maturity of crop and also in development of roots and nodulation. The soil was low in organic matter (0.8%), available nitrogen (1.76mg kg-1), phosphorus (2.9mg kg-1) and medium in available potassium (120mg kg-1). Application of vermicompost (2 t ha-1) with full dose of phosphorus (75 kg P2O5 ha-1) treatment (V1P2) fertilization markedly influenced the nutrient concentration in grains (2.56% of N, 0.3% of P, 1.23% of K), their uptake (62 kg ha-1 N, 12 kg ha-1 P, 39 kg ha-1 K) and yield (1410 kg ha-1) over control in mung bean. Economically significant nutrient contents in grain (2.44% N, 0.37% P, 1.17% K), nutrient uptake (52 kg ha-1 N, 8.91 kg ha-1 P, 31.5 kg ha-1 K) and yield (1282 kg ha-1) was observed from the treatment where half dose of fertilizer (37.5 kg P2O5 ha-1) with 2 t ha-1 vermicompost (V1P1) over control.

Arbuscular mycorrhizal (AM) symbioses are formed by approximately 80% of vascular plant species in all major terrestrial biomes. In consequence an understanding of their functions is critical in any study of sustainable agricultural or natural ecosystems. Here we discuss the implications of recent results and ideas on AM symbioses that are likely to be of particular significance for plants dealing with abiotic stresses such as nutrient deficiency and especially water stress. In order to ensure balanced coverage, we also include brief consideration of the ways in which AM fungi may influence soil structure, carbon deposition in soil and interactions with the soil microbial and animal populations, as well as plant-plant competition. These interlinked outcomes of AM symbioses go well beyond effects in increasing nutrient uptake that are commonly discussed and all require to be taken into consideration in future work designed to understand the complex and multifaceted responses of plants to abiotic and biotic stresses in agricultural and natural environments.

Twelve psychrotolerant Pseudomonad strains were selected on the basis of various plant growth-promoting (PGP) activities at cold temperature (4°C). The effect of inoculation with Pseudomonad strains on cold alleviation and growth of wheat seedling at cold temperature (8°C) was investigated under greenhouse condition. Inoculation with Pseudomonad strains significantly enhanced root/shoot biomass and nutrients uptake as compared to non-bacterized control at 60 days of plant growth. Bacterization significantly improved the level of cellular metabolites like chlorophyll, anthocyanin, free proline, total phenolics, starch content, physiologically available iron, proteins, and amino acids that are sign of alleviation of cold stress in wheat plants. Increased relative water content, reduced membrane injury (electrolyte leakage), and Na ? /K ? ratio were also recorded in bacterized wheat plants. Electrolyte leakage and Na ? /K ? were found inversely proportional to plant growth at cold temperature. Statistical analysis of twenty-three measured parameters revealed that uninoculated control was under cold stress while eight bacterial strains were positively alleviating cold stress in wheat plants. Thus, the psychrotrophic Pseudomonad strains could effectively provide a promising solution to overcome cold stress, which is major factor hindering wheat productivity under cold climatic condition.

Headwater streams represent the key sites of nutrient retention, but little is known about temporal variation in this important process. We used monthly measurements over 2 years to examine variation in retention of soluble reactive phosphorus (SRP) and ammonium (NH 4 + ) in two Mediterranean headwater streams with contrasting hydrological regimes (that is, perennial versus intermittent). Differences in retention between streams were more evident for NH 4 + , likely due to strong differences in the potential for nitrogen limitation. In both streams, nutrient-retention efficiency was negatively influenced by abrupt discharge changes, whereas gradual seasonal changes in SRP demand were partially controlled by riparian vegetation dynamics through changes in organic matter and light availability. Nutrient concentrations were below saturation in the two streams; however, SRP demand increased relative to NH 4 + demand in the intermittent stream as the potential for phosphorus limitation increased (that is, higher dissolved inorganic nitrogen:SRP ratio). Unexpectedly, variability in nutrient retention was not greater in the intermittent stream, suggesting high resilience of biological communities responsible for nutrient uptake. Within-stream variability of all retention metrics, however, increased with increasing time scale. A review of studies addressing temporal variation of nutrient retention at different time scales supports this finding, indicating increasing variability of nutrient retention with concomitant increases in the variability of environmental factors from the diurnal to the interannual scale. Overall, this study emphasizes the significance of local climate conditions in regulating nutrient retention and points to potential effects of changes in land use and climate regimes on the functioning of stream ecosystems.

The aim of this study was to access the bioassociative effect of two rhizospheric Pseudomonas spp. with effective root nodulating symbiotic nitrogen fixer Rhizobium leguminosarum-PR1 on plant growth and nutrients uptake of lentil (Lens culinaris L.) plant under greenhouse conditions. Lentil seeds of variety VL Masoor 507 were inoculated with two cold tolerant Pseudomonas sp. strains (NARs1, PGERs17) and R. leguminosarum-PR1, individually or in combination, and were grown in pots using nonsterile sandy loam Entisol. Inoculation with Pseudomonas sp. strain PGERs17 exhibits more vigorous vegetative growth with increase in nodulation (55.0%), leghaemoglobin content (27.7%), physiologically available iron (24.1%), total iron (90.7%) chlorophyll content (43.9%), P uptake (37.1%) and N uptake (27.1%) over R. leguminosarum-PR1 alone at 60 days after sowing (DAS). Coinoculation of Pseudomonas sp. strain NARs1 with R. leguminosarum-PR1 recorded maximum increase in the nodulation 27.5, leghaemoglobin content-45.9, total iron-115.7, total chlorophyll content-21.3, N uptake-52.1 and P uptake-88.9% over R. leguminosarum-PR1 alone at 60 DAS, which suggest that a strong selective synergistic relationship existed between cold tolerant Pseudomonas sp. strain NARs1 and R. leguminosarum-PR1. The variations in efficacy of different treatment combinations indicate the specificity of the inoculation response. These results provide a basis for the selection of an appropriate combination of specific Pseudomonas sp. and R. leguminosarum which could further be utilized for verifying the symbiotic effectiveness and competitive ability of microsymbionts under field condition of hill agro ecosystem.

The objective of the present research was to explore the effects of combined irrigation and fertilization (fertigation) frequency on growth, yield and uptake of water and nutritional elements by plants. Lettuce (Lactuca sativa L., cv. Iceberg) was used as the model plant. Two experiments were conducted in a screen-house: compound fertilizer at a constant N:P:K ratio at different concentrations was used in the first, while in the second the concentration of P varied solely while the concentration of the other nutritional elements was kept constant. The lettuce was planted in pots filled with perlite and irrigated daily with a constant volume of nutrient solution at different frequencies. The major finding in the two experiments was that high fertigation frequency induced a significant increase in yield, mainly at low nutrients concentration level. Yield improvement was primarily related to enhancement of nutrient uptake, especially P. It was suggested that the yield reduction obtaine...

New Zealand bracken (Pteridium esculentum) belongs to a group of closely related fern species of near global extent. Pteridium species worldwide are aggressive, highly productive, seral plants, functionally more akin to shrubs than ferns. Their deeply buried starch-rich rhizomes allow them to survive repeated fire and their efficient nutrient uptake permits exploitation of a wide range of soils. They are limited by cool annual temperatures, frost, wind, and shallow, poorly drained and acidic soils. Bracken stands accumulate large amounts of inflammable dead fronds and deep litter and often persist by facilitating fire that removes woody competitors. Bracken was present but not abundant in New Zealand before the arrival of humans. Occasional fire or other disturbances created transient opportunities for it. Rhyolitic volcanic eruptions led to short-lived expansions of bracken, and it briefly became dominant over ash-affected areas of the central North Island after the large AD 186 Taupo Tephra eruption. Andesitic eruptions had limited effects. Bracken became one of the most abundant plants in the country after the arrival of Maori in the 13th century, when massive deforestation affected most of the lowland landscape. The bracken-dominated vegetation that formed in most places immediately after burning gave way with time to fire-maintained mosaics in which bracken dominated on deeper soils and under moist, mild climates. Although Maori relied on bracken rhizome starch as a major element of their diet, food-quality rhizomes were obtained only on deep, moderately fertile soils. The dominance of bracken over very large areas was mainly a result of burning to create open landscapes for access and ease of travel. Bracken remained a troublesome weed through the European pastoral period and well into the 20th century. Bracken has a problematical role in conservation as it can form a persistent, fire-prone, low-diversity cover in drier regions. However, it is an indigenous plant that is effective in preventing erosion and, in wetter areas, it will easily suppress exotic grasses and facilitate regeneration to forest. It should be considered an essential component of landscapes conserved for their historical significance to Maori. ____________________________________________________________________________________________________________________________________

A field experiment was conducted to study the effect of vermicompost and three different levels of phosphorus fertilization on nutrient uptake in grain, straw, their total uptake and yield in mung bean at wheat program research area NARC, Islamabad. Application of phosphorus and vermicompost plays an important role in growth, development and maturity of crop and also in development of roots and nodulation. The soil was low in organic matter (0.8%), available nitrogen (1.76mg kg -1 ), phosphorus (2.9mg kg -1 ) and medium in available potassium (120mg kg -1 ). Application of vermicompost (2 t ha -1 ) with full dose of phosphorus (75 kg P 2 O 5 ha -1 ) treatment (V1P2) fertilization markedly influenced the nutrient concentration in grains (2.56% of N, 0.3% of P, 1.23% of K), their uptake (62 kg ha -1 N, 12 kg ha -1 P, 39 kg ha -1 K) and yield (1410 kg ha -1 ) over control in mung bean. Economically significant nutrient contents in grain (2.44% N, 0.37% P, 1.17% K), nutrient uptake (52 ...