Plant Tissue Nutrient Concentrations Research Articles

Managing the interactions between soil abiotic factors to alleviate the effect of Fusarium wilt in bananas

Soil management offers various options to alleviate the effects of Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) in bananas. Nevertheless, it receives little attention as a strategy in Fusarium wilt management. Literature provides ample evidence linking soil conditions such as soil texture and fertility to the spread and severity of plant diseases. However, the inconsistency of results between case studies limits the attention of soil management in crop disease management. The present study aimed at unravelling the role of soil abiotic factors on nutrient concentrations in plant tissue, biomass production and the incidence of Fusarium wilt (Foc race 1) in bananas ('Gros Michel', AAA) under field conditions. A large field trial was established in which the effects of soil pH and nutrients (N, Ca, Mg and Mn) were studied. Around 30% of the plants showed symptoms of Fusarium wilt at flowering in the first season. However, Fusarium wilt incidence did not vary between treatments. Soil pH showed significant interactions with soil N and Mn concentrations resulting in a lower bunch weight and increased micronutrient concentrations in the pseudostem. With a higher pH, bunch weight increased, although higher Mn concentrations suppressed this positive effect. Interactions between a high soil pH and Ca and Mg resulted in a higher bunch weight and lower micronutrient concentrations in the pseudostem. The results can be used to develop soil management strategies for improving banana productivity in infected plantations.

Nitrogen fixation ability explains leaf chemistry and arbuscular mycorrhizal responses to fertilization

Atmospheric nitrogen (N) and phosphorus (P) deposition rates are predicted to drastically increase in the coming decades. The ecosystem level consequences of these increases will depend on how plant tissue nutrient concentrations, stoichiometry and investment in nutrient uptake mechanisms such as arbuscular mycorrhizal fungi (AMF) change in response to increased nutrient availability, and how responses differ between plant functional types. Using a factorial nutrient addition experiment with seedlings of multiple N-fixing and non-N-fixing tree species, we examined whether leaf chemistry and AMF responses differ between these dominant woody plant functional groups of tropical savanna and dry forest ecosystems. We found that N-fixers have remarkably stable foliar chemistry that stays constant with external input of nutrients. Non-N-fixers responded to N and N + P addition by increasing both concentrations and total amounts of foliar N, but showed a corresponding decrease in P concentrations while total amounts of foliar P stayed constant, suggesting a ‘dilution’ of tissue P with increased N availability. Non-N-fixers also showed an increase in N:P ratios with N and N + P addition, probably driven by both an increase in N and a decrease in P concentrations. AMF colonization decreased with N + P addition in non-N-fixers and increased with N and N + P addition in N-fixers, suggesting differences in their nutrient acquisition roles in the two plant functional groups. Our results suggest that N-fixers and non-N-fixers can differ significantly in their responses to N and P deposition, with potential consequences for future nutrient and carbon cycling in savanna and dry forest ecosystems.

Genetic variation in compensatory feeding for dietary dilution in a generalist caterpillar

Increasing the rate of food consumption is a common adaptive strategy that allows herbivores to compensate for declines in nutrient concentrations in plant tissues. Herbivores that are better able to compensate for dietary dilution may have selective advantages under nutritionally poor conditions. In order for compensatory feeding to respond to selection, there must be standing heritable variation for this trait. However, empirical data substantiating the adaptive significance and genetic variability of compensatory feeding are rare. By employing a full-sib, split-brood design, this study presents quantitative genetic analyses on the nutrient consumption rates of the generalist caterpillar, Spodoptera exigua, raised on semi-synthetic diets differing in nutrient concentrations. When encountering a diluted diet, caterpillars exhibited a compensatory increase in food consumption rate, but the extent of this increase was not sufficient to fully compensate for dietary dilution. A significant gene-environment interaction for consumption rate indicated that the capacity of caterpillars to compensate for dietary dilution varied across genotypes. The broad-sense heritability of compensatory feeding was 0.51. Caterpillar genotypes with a higher compensatory capacity suffered lower performance losses on the diluted diet than did those with a lower capacity. This study has implications for understanding how herbivores can evolutionarily respond to nutritional challenges.

Chromium from Hydrolyzed Leather Affects Soybean Growth and Nodulation

Hydrolyzed leather, obtained from industrial leather waste, is an organic nitrogenous fertilizer with a high chromium (Cr) content. Soybean crops can be adversely affected by the presence of residual Cr in soil after application of hydrolyzed leather fertilizer. The aim of this work was to assess the effect of hydrolyzed leather on Cr absorption, root development, and symbiotic nodulation of soybean plants grown on three different soils including two Lixisols and a Gleysol. These soils were previously fertilized with hydrolyzed leather at three different rates (0.0, 0.1, and 0.8 kg m−2). Soybean shoot height, root development, nodulation, and mineral nutrient concentrations in plant tissues were determined after 45 d of crop growth. The application of hydrolyzed leather significantly increased Cr content in soil and Cr uptake by plants. Surprisingly, Cr was stored mainly in the aerial part of the plants. The presence of Cr had an adverse impact on shoot dry matter (41% reduction) and number of nodules (49% reduction) per plant grown on the soil with the lowest cation exchange capacity. However, no other significant effect was observed in nodule weight, diameter, or any other measured parameters.

Nitrogen:phosphorous supply ratio and allometry in five alpine plant species.

In terrestrial ecosystems, atmospheric nitrogen (N) deposition has greatly increased N availability relative to other elements, particularly phosphorus (P). Alterations in the availability of N relative to P can affect plant growth rate and functional traits, as well as resource allocation to above‐ versus belowground biomass (M A and M B). Biomass allocation among individual plants is broadly size‐dependent, and this can often be described as an allometric relationship between M A and M B, as represented by the equation MA=αMBβ, or log M A = logα + βlog M B. Here, we investigated whether the scaling exponent or regression slope may be affected by the N:P supply ratio. We hypothesized that the regression slope between M A and M B should be steeper under a high N:P supply ratio due to P limitation, and shallower under a low N:P supply ratio due to N limitation. To test these hypotheses, we experimentally altered the levels of N, P, and the N:P supply ratio (from 1.7:1 to 135:1) provided to five alpine species representing two functional groups (grasses and composite forbs) under greenhouse conditions; we then measured the effects of these treatments on plant morphology and tissue content (SLA, leaf area, and leaf and root N/P concentrations) and on the scaling relationship between M A and M B. Unbalanced N:P supply ratios generally negatively affected plant biomass, leaf area, and tissue nutrient concentration in both grasses and composite forbs. High N:P ratios increased tissue N:P ratios in both functional groups, but more in the two composite forbs than in the grasses. The positive regression slopes between log M A and log M B exhibited by plants raised under a N:P supply ratio of 135:1 were significantly steeper than those observed under the N:P ratio of 1.7:1 and 15:1. Synthesis: Plant biomass allocation is highly plastic in response to variation in the N:P supply ratio. Studies of resource allocation of individual plants should focus on the effects of nutrient ratios as well as the availability of individual elements. The two forb species were more sensitive than grasses to unbalanced N:P supplies. To evaluate the adaptive significance of this plasticity, the effects of unbalanced N:P supply ratio on individual lifetime fitness must be measured.

Traits Driving Tolerance to Atmospheric Fluoride Pollution in Tree Crops

Increased emissions of fluoride into the atmosphere contribute to reducing the sustainability of agricultural systems worldwide. In order to improve the understanding of the factors behind such phenomenon, varieties of citrus (Citrus spp.), Valencia sweet-orange, Ponkan mandarin, and Lisbon lemon and coffee (Coffea spp.), Obata, Catuai, and Apoata, were treated with fluoride nebulization. The trees were exposed to nebulization for 60 min inside a chamber by using medium (0.04 mol L−1) and high (0.16 mol L−1) doses of fluoridic acid (HF) during three nonconsecutive days in a single week, for a total of 26 days of exposure during the experiment. Sixty days after beginning nebulization, we evaluated leaf gas exchange, (ultra)structural organization, tree growth, and fluoride and nutrient concentrations in plant tissue. Photosynthesis and leaf dry mass of citrus and coffee varieties were affected differently by fluoride toxicity, and based on the tolerance index (relative leaf dry mass of control versus leaf dry mass of trees treated with 0.16 mol L−1 HF), the order of sensitivity for the varieties of each species was as follows: for citrus, lemon > mandarin > sweet-orange; and for coffee, Apoata > Catuai > Obata. The ability of the trees to control fluoride absorption most likely explained this contrast in sensitivity among varieties because both photosynthesis and leaf growth were negatively correlated with leaf fluoride concentration. Although disorganization of the thylakoids, degeneration of vascular cells, and disruption of the middle lamella occurred in leaves of all varieties exposed to fluoride, the more severe damage was observed in those with greater sensitivity to the pollutant (i.e., lemon and Apoata coffee). Taken together, these results provided insights into the factors that explain poor performance of citrus and coffee trees under fluoride pollution and also revealed the traits driving the tolerance of these crops such a limiting condition, which included a combination of the following: (i) reduced fluoride absorption, (ii) increased photosynthesis, and (iii) improved maintenance of the ultrastructural organization of leaves.

Effect of nitrogen– boron interaction on plant growth and tissue nutrient concentration of canola (Brassica napus L.)

ABSTRACTPot experiments were conducted in the greenhouse on a calcareous soil to study the effect of nitrogen on the alleviation of boron toxicity in canola (Brassica napus L.). The treatments consisted of factorial combination of six levels of B (0, 2.5, 5, 10, 20, and 40 mg kg−1 as boric acid), and four levels of nitrogen (N) (0, 75, 150 and 300 mg kg−1 as urea) in a completely randomized design with three replicates. Boron (B) application significantly reduced the yield, whereas N addition alleviated the growth suppression effects caused by B supplements. Boron concentration increased with addition B. However, boron concentration in shoot declined with increasing N levels. Increasing N and B rates increased N concentration. Soil application of B increased proline concentration. However, the supply of N decreased it. Generally, application of B decreased potassium (K):B and calcium (Ca):B ratios, chlorophyll concentration, while N application increased them. It is concluded that N fertilization can be used effectively in controlling B toxicity in canola grown in B-affected soils.

Using high-resolution, multispectral imagery to assess the effect of soil properties on vegetation reflectance at an abandoned feedlot

Remotely sensed multispectral imagery, soils and graminoid samples from an abandoned cattle feedlot and adjacent wetlands were used to characterize plant vigour and soil nutrient distribution and evaluate the relationship between soil properties and vegetation reflectance. The feedlot lies on a sandy beach ridge, which likely mitigates the mobility of soil phosphorus. Soil phosphorus remains concentrated directly beneath the feedlot pens, where vegetation indices are low. In contrast, nitrate is transported through preferential pathways into the wetlands, where vegetation indices and plant vigour are high. Although spectral vegetation indices did not show any significant relationship with plant tissue nutrient concentration, the indices showed statistically significant relationships to some soil properties. Results of this study indicate that the abundance of nutrients in the soil does not necessarily enhance plant growth. This can limit the extent that remotely sensed vegetation indices can be used to evaluate soil nutrients concentrations.

Responses of a Grassland Ecosystem to 17 Years of Free-air CO2 Enrichment

Grasslands comprise 70% of all agricultural land worldwide, and provide fodder for life-stock and besides being habitats for flora and wildlife, they contain large carbon and nitrogen stocks. Elevated CO2 concentrations usually increase plant growth in the short-term, particularly in well- fertilized and irrigated crops. Furthermore, plant tissue nutrient concentrations decrease and the subsequent increase in the CN ratio is assumed to be a symptom of a “progressive nitrogen limitation” (PNL), which is still under debate since long-term FACE experiments are scarce.The Giessen FACE experiment started in a N-limited, species-rich grassland ecosystem near Giessen, Germany in 1998. The CO2 concentration was enriched (eCO2) +20% above ambient (aCO2) year-round during daylight hours. Biomass was harvested twice: in spring and late summer, sorted into the functional groups grasses, forbs and legumes, and the plant material was analyzed (Inductively Coupled Plasma Mass Spectrometer ICP–MS and MS) for N and other nutrients.Biomass of grasses was increased by elevated CO2 during the whole 17 years (1998-2014) indicating that dominant grasses react quickly to elevated CO2, while biomass of forbs was first smaller under elevated CO2 until 2007, and then became larger at eCO2 from 2008 to 2014.Elemental concentrations (Ca, Mg, S, N) were decreased by elevated CO2 in grasses, forbs and legumes. However, K and Zn concentrations in forbs and Mn in legumes increased under elevated CO2. During the first 11 years (1998-2008), the removed net N pool with the harvested biomass, was identical under elevated and ambient CO2 conditions, revealing increased N use efficiency under elevated CO2. Weather conditions (extreme summers) should also be taken into account to better understand the mechanisms of long-term biomass response.Our preliminary conclusions are (1) the increasing yield response over time does not support PNL in N-limited grassland, (2) co-existing functional plant groups have different response patterns.

Defining Sufficiency Levels of Nitrogen in Cool‐Season Turfgrass Lawns Using Macy's Concept

ABSTRACTFew correlation or calibration studies have been conducted to determine or validate sufficiency levels of N concentrations in the clippings of turfgrass for color and growth responses. In a series of field experiments conducted across six consecutive growing seasons (2007–2012) in Connecticut, clipping samples of Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) lawns were used to estimate yields and then analyzed for N concentrations. Chlorophyll and normalized difference vegetative index (NDVI) meters were used to quantify turf color before sampling. Macy's concept of three nutritional zones of plant tissue nutrient concentration was used to identify minimum and critical concentrations of N in the clippings that define sufficiency ranges for color and growth responses, in addition to luxury consumption. Averaged across all variables and seasons (spring, summer, and fall), the sufficiency ranges of N concentration in the clippings were estimated to be 32 to 46 g kg–1 for Kentucky bluegrass, and 28 to 42 g kg–1 for tall fescue. Differences in minimum and critical concentrations among seasons and between species were thought to be due to demand‐driven nutrient uptake. Luxury consumption of N was observed in both species. When used in context with local conditions, tissue analysis for N concentrations in cool‐season turfgrass clippings can provide an objective basis for guiding N fertilization.

Soil–Plant Nutrient Interactions on Manure‐Enriched Calcareous Soils

Growers working with manured soils often rely on soil test information when developing nutrient management for their crop, especially when manure application information is unavailable. Nutrient‐enriched soils, like manured soils, can trigger nutrient deficiencies and toxicities due to plant–soil nutrient interactions. The goal of the study was to determine correlations between soil test and plant tissue nutrient concentrations for irrigated corn silage crops (Zea mays L. subsp. mays) with varying nutrient concentrations unique to dairy manure‐enriched calcareous soils. Whole plant and soil samples were collected from 39 cooperator corn silage fields at harvest over a 2‐yr period throughout the Snake River Plain region of southern Idaho. Soils were sampled to a depth of 30.5 cm and analyzed for plant available forms of P, K, Ca, Mg, Na, S, Zn, Fe, Mn, Cu, and B; whole plant tops were analyzed for total N, P, K, Ca, Mg, Na, S, Zn, Fe, Mn, and Cu. Significant positive correlations were detected between soil test K and tissue K (Spearman’s rho correlation coefficient = 0.63), soil test K and tissue N (rho = 0.59), and soil test B and tissue N (rho = 0.53). A significant negative correlation was detected between soil test Fe and tissue Mn (rho = –0.59). Controlled studies are needed to corroborate the relationships observed in this survey study.

Responses of the Azolla filiculoides Stras.–Anabaena azollae Lam. association to elevated sodium chloride concentrations: Amino acids as indicators for salt stress and tipping point

The water fern genus Azolla has been found in marine sediments, showing that ancestral species grew in marine ecosystems during the Eocene. Modern Azolla species, however, only live in freshwater. Besides aiming to elucidate experimentally the conditions that prevailed over the Arctic Ocean and adjacent Nordic seas during the Eocene, studies on tolerance of these plants to salt stress have applied potential, as Azolla may be used as a fertilizer, due to its symbiosis with N2-fixing Anabaena cyanobacteria, and grown on salt-infiltrated agricultural fields. Here, the response of a temperate Azolla filiculoides–Anabaena azollae association to a wide salinity gradient (0–210mM NaCl) was studied by measuring growth, nutrient content, nitrogenase activity and the accumulation of free amino acids in the association. The association was able to grow at salt concentrations up to 90mM NaCl and appeared to acclimate in this range, but only after a period of 75 days. At concentrations exceeding 120mM NaCl, however, roots were shed and impairment of water and nutrient uptake (including dinitrogen fixation) resulted in die off. Increased Na concentrations in the plants grown at external salt concentrations of 30mM NaCl were to some extent reverted by decreased K concentrations, suggesting that K in the plants was replaced by Na as plant growth was not affected. Absolute nutrient concentrations in plant tissue were not correlated with plant growth and therefore not suitable as reliable indicators for salt stress. However, significant increases in the free amino acids proline and glutamate and significant decreases in asparagine, glutamine and gamma-amino-butyric-acid were found with increasing salinity. The constitutively high glutamine concentrations in the plants grown up to 90mM NaCl may have contributed to the salt tolerance of the plants by providing osmotic adjustment. Proline concentrations and glutamine/glutamate ratios proved to be strong linear indicators for the level of salt stress and can therefore be used to predict the tipping point concentration. The salt resistance limit of 90mM NaCl corresponds well to climate model predictions of salinity levels of ancestral habitats of Azolla in the Eocene Arctic Ocean.

Faixas normais de nutrientes pelos métodos ChM, DRIS e CND e nível crítico pelo método de distribuição normal reduzida para laranjeira-pera

A utilização de métodos de diagnose nutricional para definição de teores ótimos e níveis críticos de nutrientes em tecidos vegetais tem se demonstrado promissora, desde que se conheçam suas limitações. Este trabalho teve como objetivo determinar as faixas normais de nutrientes para a cultura da laranjeira-pera em uma população, utilizando os métodos Chance Matemática (ChM), Sistema Integrado de Diagnose e Recomendação (DRIS) e Diagnose da Composição Nutricional (CND), além do Nível Crítico, pelo método de distribuição normal reduzida. O trabalho foi realizado no município de Bebedouro-SP, na Estação Experimental de Citricultura de Bebedouro. Utilizaram-se como base de dados teores totais de nutrientes de 50 amostras foliares e a produtividade da laranjeira-pera, oriundas de um experimento cujo fator de avaliação foram doses de calcário aplicadas superficialmente. Para o N, maior valor de ChM foi obtido pela classe 2 (23,6 a 24,7 g kg-1), com valores semelhantes aos obtidos pelo DRIS (22,1 a 24,0 g kg-1) e CND (22,1 a 23,9 g kg-1). Os valores inferiores dessas faixas normais concordam com o do nível crítico alcançado (22,7 g kg-1), sendo este muito próximo do proposto pela literatura. Para os nutrientes P, K, Mg, Zn e B, as faixas normais e os níveis críticos não se assemelharam aos descritos na literatura. Em relação aos nutrientes Ca, Fe, Mn e Cu, seus valores de faixa normal e nível crítico aproximaram-se dos recomendados, possivelmente devido à maior variação em seus teores. A utilização dos métodos propostos, em uma população, foi mais adequada quando houve maior variação nos teores dos nutrientes, além de possibilitar menor amplitude aos valores de faixas normais, quando comparados aos da faixa de terras suficientes encontrados na literatura.

Effect of Low pH on the Growth, Physiological Characteristics and Nutrient Absorption of Sago Palm in a Hydroponic System

The dry matter production, photosynthetic characteristics and nutrient concentrations in the plant tissues of sago palmseedlings cultured for 4.5 months in a hydroponic system at pH 5.7, 4.5, and 3.6 were examined. Plant growth in weekly increment of length, leaf emergence, leaf senescence, and total leaflet area was similar at all pHs. There was no significanteffect of pH on the dry matter weight, although it tended to be lighter at pH 3.6 than at pH 5.7. Similarly, the photosynthetic rate and its related parameter were not significantly affected by the pH. However, the photosynthetic rate at pH 3.6tended to be lower than that at pH 5.7, which was attributed to a decrease in the stomatal conductance. The effect of the low pH on the nutrient concentration in plant tissues was not distinct. We concluded that sago palm seedlings could maintain leaf morphogenesis and nutrient uptake in growth media at a pH ranging from 5.7 to 3.6 for 4.5 months, which led to a high growth rate and maintenance of dry matter production even at pH 3.6.

Salinity exposure modifies nutrient concentrations in fenugreek (Trigonella foenum graecum L.).

Salinity is one of the most important abiotic factors limiting plant growth and yield. Salinization occurs naturally in arid and semiarid regions where evaporation is higher than rainfall. In this study, the effect of different concentrations of NaCl (0, 50, 100, 150, 200 and 250 mM) on mineral ions content in various plant organs of fenugreek (Trigonella foenum graecum L.) was investigated. Fenugreek plant was divided into root, shoot, leaf and pod parts for nutrient (Ca, Na, K, Cl, P, Fe, Mn, Cu and Zn) content measurements. Results indicated that the nutrient concentrations in plant tissues like leaves, roots, shoots and pods of fenugreek was strongly affected by all salt treatments. The chloride and sodium ions increased significantly in various parts of the plant depending on salinity increase. Specifically, increased salt concentration caused an increase in some nutrient contents (Na, Cl, P, Fe, Mn, Cu and Zn), while same factor caused a decrease in some nutrient contents (Ca and K). In general, an evident increase in nutrient composition in plant organs was observed mainly at the higher level of salt concentration when compared to control. Key words: Fenugreek (Trigonella foenum-graecum L.), salt stress, nutrient concentration.

Organic Soil Amendment and Tillage Affect Soil Quality and Plant Performance in Simulated Residential Landscapes

The urban soil environment is usually not conducive to healthy root growth and function, leading to problems with plant establishment, growth, and aesthetic quality. The objective of this study was to determine if the addition of compost with or without the application of shallow tillage or aeration will improve soil physical and chemical properties and plant growth compared with an unamended control in simulated new residential landscapes. Twenty-four mixed landscape plots were established in a randomized complete block design to simulate new residential landscapes. Each plot was constructed using 10 cm of subsoil fill material over a compacted field soil and planted with Stenotaphrum secundatum and mixed ornamental plant species. Composted dairy manure solids were applied as an organic soil amendment at a depth of 5 cm (≈256 Mg·ha−1) in combination with two mechanical soil treatments (tillage to 15 cm and plug aeration) for a total of five soil management treatments plus an untreated control. Soil physical and chemical properties, plant growth, and quality and plant tissue nutrient concentrations were assessed periodically to determine the effect of soil treatment on soil and plant quality. Applications of compost to soils significantly reduced soil bulk density and pH and increased soil organic matter, electrical conductivity, and Mehlich-1 phosphorus and potassium concentrations. All ornamental plant species, with the exception of Raphiolepis indica (L.) Lindl. ex Ker Gawl., exhibited more growth when grown in soils amended with composted dairy manure solids. In most instances, plant tissue nitrogen and phosphorus concentrations were higher for plants grown in soils receiving compost. Results of our study suggested that the addition of composted dairy manure solids to soils can improve soil properties and enhance plant growth in residential landscapes when sandy fill soils are used. In contrast, shallow tillage and aeration had little effect on soil properties or plant growth.

Interspecific and geographical differences of plant tissue nutrient concentrations along an environmental gradient in Southern Patagonia, Chile

Foliar nutrient concentrations of South Patagonian ombrotrophic peatland species were analyzed along a gradient of increasing continentality. We paid particular attention to nutrient demands of Sphagnum magellanicum, the dominant constituent of continental raised bogs, and to those of cushion-forming vascular plants such as Astelia pumila, dominating in western hyperoceanic blanket bogs. With exception of one graminoid species, nutrient concentrations in leaf tissues were generally low, but showed considerable variation. Extremely low concentrations were measured in S. magellanicum reflecting the unpolluted, pristine character of the investigated bog ecosystems. Nutrient concentrations in cushion plants showed remarkable variation. While nutrient concentrations in Donatia fascicularis were almost as low as in S. magellanicum, they were significantly higher in A. pumila. Variation in foliar nutrient concentrations was predominantly due to differences between species. Nevertheless, there was a significant shift within species along the considered west-to-east continental gradient. The stronger minerotrophic character of the western cushion bogs was reflected by higher Ca contents. N concentrations increased and P concentrations decreased westward in most species. Consequently, the most noticeable shift was an increasing N:P ratio indicating a higher degree of P limitation towards western cushion dominated blanket bogs.

Recent Land Cover History and Nutrient Retention in Riparian Wetlands

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus].

Environmental limitation contributes to the differential colonization capacity of two forest herbs

AbstractQuestion: The recovery of forest plant communities in post‐agricultural landscapes is largely determined by dispersal constraints, but can environmental legacies of former land use additionally limit the recolonization of recent forests by forest herbs?Location: Ancient forest and recent forest on former heavily fertilized agricultural land (Muizenbos, northern Belgium).Methods: Seeds and adults of two forest herbs with similar life‐history traits, but contrasting colonization capacity – the fast‐colonizing Geum urbanum and the slow‐colonizing Primula elatior– were introduced into both ancient and recent forest sites. Soil conditions and plant tissue nutrient concentrations were measured to characterize habitat quality. To determine whether the introduced species could successfully establish and persist, we monitored recruitment, longevity and adult performance during 8 years in permanently marked plots.Results: Phosphorus availability was ten times higher in recent forest soils and was also reflected in the plant tissue samples. Species longevity was clearly lower in recent forest sites indicating higher turnover. The fast‐colonizing G. urbanum counterbalanced this lower longevity by new establishment, while the slow‐colonizing P. elatior dropped below the number of originally introduced individuals. Additionally, G. urbanum performed better in recent forest sites in contrast to P. elatior.Conclusions: Even when dispersal constraints of the slow‐colonizing forest herb P. elatior are eliminated through introduction, environmental conditions in recent forest sites additionally restrict its recruitment, longevity and performance. These experimental results suggest that environmental constraints may strengthen the differences in colonization capacity among forest herbs if slow dispersers also tend to be less likely to establish.

Improvement of soil properties using compost for optimum parsley production in sandy soils

In the warm and wet north Florida climate, growing Italian parsley ( Petroselinum crispum [Mill.]) is gaining popularity with small producers as a short duration crop on sandy soil. Application of compost to agricultural land can benefit the low fertile sandy soils in Florida and subsequent crop production, while providing an outlet for recycling municipal solid wastes (MSW) and biosolids. A field study was laid out in a randomized complete block design with four replications to evaluate the effects of compost (75% MSW:25% biosolids) application in comparison to fertilizer, fertilizer + compost (50:50), and control treatments on: (a) parsley fresh weight (FW), (b) soil and plant tissue nutrient concentrations, and (c) soil bulk density and moisture retention in winter and spring seasons. Soil amended with fertilizer or compost + fertilizer doubled parsley FW from 15.02 Mg ha −1 in the non-amended control plot to 30.75 and 32.67 Mg ha −1 in soils that received fertilizer + compost or fertilizer alone, respectively. Significantly higher total soil carbon (C) levels of 2.16% and 1.95% and nitrogen (N) levels of 0.19% and 0.16% were recorded in compost and fertilizer + compost treatments, respectively. Addition of compost reduced soil bulk density significantly to 1.03 Mg m −3 and increased soil moisture retention in simulated drier conditions at 1500 kPa to 0.12 m 3 m −3 in plots that received only compost at the end of winter growing season. Overall, addition of compost resulted in improvement of both physical and chemical properties as well as increased parsley yields.