Tissue Nutrient Concentrations Research Articles

Increase in phosphorus concentration reduces the toxicity of copper in wheat roots (Triticum aestivum L.)

The increase in the availability of phosphorus (P) can reduce the toxicity of copper (Cu) to plants because it favors the formation of complexes and precipitates, reducing the bioavailability of this metal. The objective of this study was to investigate the capacity of P supplementation to decrease the phytotoxicity of excess Cu in the growth and in physiological parameters of wheat plants. Plants of wheat (Triticum aestivum L.) were cultivated on sand substrate and, for 30 days, submitted to the control treatments - Hoagland & Arnon solution 100% (H&A); H&A + 47 mg P L−1 (H&A + P); H&A + 28 Cu mg L−1 (H&A + Cu); H&A + 47 mg P L−1 + 28 mg Cu L−1 (H&A + P + Cu). Plant growth, tissue nutrient concentration, photosynthetic pigment concentration, chlorophyll a fluorescence and superoxide dismutase enzyme activity in the leaves were evaluated. We observed that the treatments H&A + P and H&A + Cu provided higher height, while H&A + P + Cu provided higher dry matter yield of shoots and roots in plants. A higher Cu content in the leaves was observed in the plants cultivated with addition of 28 mg Cu L−1, however the application of Cu did not cause loss of photochemical energy and energy dissipation in the PSII antenna complex. The addition of 47 mg P L−1 provided a higher rate of electron transport in wheat plants. Therefore, wheat plants were tolerant to increasing the concentration of Cu in the culture medium and the addition of P attenuated the toxic effects caused by Cu, mainly in the roots of plants.

Customizing the leaf tissue nutrient ranges for blue and pink hydrangeas

Pink, blue, and red hydrangea [(Hydrangea macrophylla subsp. Macrophylla var. macrophylla (Thunb.)] cultivars contain the anthocyanin pigment delphinidin-3-glucoside that color the sepal. Without aluminum (Al), the natural color of the pigment is pink or red depending on the cultivar. To produce blue sepals, plants are fertilized with Al2(SO4)3 (AS) under low phosphorus (P) conditions. To determine the effect of AS on nutrient tissue concentrations ‘Early Blue’, ‘Hor Tivoli’, ‘Jip’, and ‘Mathilda Gutges’ plants were treated with 0 (pink), 12, or 15 g (blue) of AS. Pre-bloom leaf tissue concentrations were analyzed with blue cultivars generally having higher concentrations of sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), boron (B), copper (Cu), and Al, while the pink plants had higher nitrogen (N), P, calcium (Ca), and magnesium (Mg) concentrations. Concentrations of N, potassium (K), Mg, B and Cu were consistent with published sufficiency ranges regardless of color or cultivar, while S, Fe, Mn and Zn concentrations were below sufficiency in some pink cultivars. The P concentrations in both pink and blue cultivars and Ca in some blue cultivars were lower than the published sufficiency range. The difference in leaf tissue nutrient concentrations among cultivars and coloration, suggest that nutrient uptake in hydrangeas varies and that lab recommendations should be customized depending on cultivar and color production system.

Physiological, nutritional, and molecular responses of Brazilian sugarcane cultivars under stress by aluminum.

BackgroundSugarcane is a crop of global importance and has been expanding to areas with soils containing high levels of exchangeable aluminum (Al), which is a limiting factor for crop development in acidic soils. The study of the sugarcane physiological and nutritional behavior together with patterns of gene expression in response to Al stress may provide a basis for effective strategies to increase crop productivity in acidic soils.MethodsSugarcane cultivars were evaluated for physiological parameters (photosynthesis, stomatal conductance, and transpiration), nutrient (N, P, K, Ca, Mg, and S) and Al contents in leaves and roots and gene expression, of the genes MDH, SDH by qPCR, both related to the production of organic acids, and SOD, related to oxidative stress.ResultsBrazilian sugarcane RB867515, RB928064, and RB935744 cultivars exhibited very different responses to induced stress by Al. Exposure to Al caused up-regulation (SOD and MDH) or down-regulation (SDH, MDH, and SOD), depending on the cultivar, Al level, and plant tissue. The RB867515 cultivar was the most Al-tolerant, showing no decline of nutrient content in plant tissue, photosynthesis, transpiration, and stomatal conductance after exposure to Al; it exhibited the highest Al content in the roots, and showed important MDH and SOD gene expression in the roots. RB928064 only showed low expression of SOD in roots and leaves, while RB935744 showed important expression of the SOD gene only in the leaves. Sugarcane cultivars were classified in the following descending Al-tolerance order: RB867515 > RB928064 = RB935744. These results may contribute to the obtention of Al-tolerant cultivars that can play their genetic potential in soils of low fertility and with low demand for agricultural inputs; the selection of potential plants for breeding programs; the elucidation of Al detoxification mechanisms employed by sugarcane cultivars.

Using Constructed Floating Wetlands to Remove Nutrients from a Waste Stabilization Pond

This study reports the biomass accumulation, plant nutrient concentration, and nutrient uptake rates of plants in a constructed floating wetland (CFW) installed for a sewage treatment application in Australia. Plant biomass accumulation was estimated based on field samplings throughout the duration of the study. Analysis of samples of each plant species was also completed to estimate the mean plant tissue nutrient content. The plant biomass accumulation estimate and the mean plant tissue nutrient concentration were then used to estimate the total nutrient uptake for each species. Each of the species were found to differ in biomass accumulation and plant tissue nutrient concentration and the distribution of biomass and nutrients between the shoots and roots. The nutrient uptake rates varied between the species, with B. articulata having the greatest nutrient uptake rates (shoots: N, 104 ± 31.5 g/m2, P, 12.9 ± 3.87 g/m2; roots: N, 23.9 ± 7.23 g/m2, P, 5.54 ± 1.67 g/m2). Harvesting of the four CFW islands after 375 days of growth removed an estimated 23.2 kg of N and 2.97 kg of P. The results of this study indicate that the use of CFWs with carefully selected plant species can successfully remove significant amounts of nutrients from domestic wastewater.

Effect of gibberellic acid and titanium dioxide nanoparticles on growth, antioxidant defense system and mineral nutrient uptake in wheat

Nanoparticles (NPs), as a novel source of industrial materials, have been extensively used in recent years which ultimately ends up in soils and may cause toxic effects on plants. Gibberellic acid (GA), phytohormone, has ability to minimize abiotic stresses in plants. The role of GA in minimizing titanium dioxide (TiO2) NPs stress in plants is still unknown. In current study, soil was spiked with TiO2 NPs (0, 100, 200, 400, 600 mg/kg) while GA was foliar-sprayed at different concentrations during wheat growth. The findings revealed that TiO2 NPs increased the growth, chlorophyll contents, and nutrient (P, K, Fe, Mn) concentrations in tissues till 400 mg/kg and then decrease was observed at 600 mg/kg level of NPs whereas the values of these parameters were higher compared to control irrespective of NPs levels. The NPs enhanced the antioxidant activities (SOD, POD, CAT, APX) and reduced the oxidative stress (EL, H2O2, MDA) in leaves over the control. Foliar GA further improved the growth, yield, nutrients and antioxidant activities while minimized the oxidative stress compared to respective sole NPs- treatments. The interactive effects of NPs and GA were dose dependent. The results proved that studied doses of TiO2 NPs were not toxic to wheat plants except the highest level (600 mg/kg) used and GA positively affected the yield of wheat under TiO2 NPs application. The GA can be used to improve crop growth in the presence of NPs which, however, needs further investigation at higher doses of TiO2 NPs in various crops.

The effect of distal‐end trimming onSaccharina latissimamorphology, composition, and productivity

AbstractAs kelp cultivation increases around the world, so does the need for farm management strategies that produce specific crop characteristics, optimize yield, widen harvesting windows, and prevent biomass loss. Distal‐end trimming of macroalgae has been recommended as a farm management method addressing these needs. In this study, we trimmed cultivatedSaccharina latissimasporophytes grown in the Western Gulf of Maine (WGoM) to 60 cm above the stipe–blade interface. We characterized the effect of trimming on the morphology, tissue nutrient content, stable isotope ratio, and nitrate reductase activity of the kelp. We also evaluated the economic trade‐offs of trimming using a simple production model. The results suggest that trimming the blade to 60 cm may have minimal biological consequences. Additionally, the trimming appears to benefit “short” kelp blades in proximity to the trimmed blades. Daily yield (% increase in weight day−1) after trimming was initially lower than the control, but late‐season daily yields and crop‐retention following storms were markedly improved. Ultimately, we conclude that growers could use trimming to acquire kelp biomass earlier in the season, retain late‐season biomass, and potentially increase the total revenue gained from kelp farming if price premiums can be exacted for this biomass.

Evaluating the Endophytic Activities of Beauveria bassiana on the Physiology, Growth, and Antioxidant Activities of Extracts of Lettuce (Lactuca sativa L.).

Endophytic entomopathogens have growth promoting, nutrient fortifying, and anti-insect properties that could improve the yield and quality of lettuce (Lactuca sativa L.). Lactuca sativa is a vegetable crop with high demand; however, it is susceptible to aphid infestations. This study’s objectives were to assess the pathogenicity of Beauveria bassiana (strain: SM3) (Bals.) Vuil. (Hypocreales) against Myzus persicae Sulzer, tissue colonization of lettuce by conidia of B. bassiana, as well as the effects of fungal inoculation on growth, tissue nutrient content, and proximate composition of the lettuce plants. Furthermore, the involvement of tissue nutrients in mediating the influence of endophytic fungus on the plant traits was examined. Insects and plants were exposed to four fungal conidial concentrations: 0, 1 × 106, 1 × 107 and 1 × 108 conidia mL−1 in an anti-insect bioassay and a greenhouse experiment, respectively. The B. bassiana strain was pathogenic against M. persicae, inducing mean insect mortality of 78% at the highest concentration (1 × 108 conidia mL−1). The B. bassiana endophytically colonized up to 76% of plants exposed to 1 × 108 conidia mL−1. Crown size and plant height varied significantly among treatments. However, the plant fresh and dry weights and nutrient elements N, P, K, Ca, and Mg did not vary significantly among treatments. Among the plant macronutrients assessed, only tissue carbon content was significantly (p < 0.01) affected by conidial treatments. The tissue C and Cu contents significantly correlated with the antioxidant capacity of the lettuce plants. Most of the micronutrients, viz. Mn, Fe, Cu, and B were remarkably higher (p < 0.05) in the fungus-treated plants than in the control plants. The antioxidant capacity (FRAP and TEAC) of plant extracts varied significantly (p < 0.001) among treatments, with the highest conidial treatment yielding the most increased antioxidant activity. In conclusion, the B. bassiana strain was endophytic to lettuce, pathogenic against M. persicae, and induced increased micro-nutrient tissue contents and antioxidant activities. This study demonstrated that B. bassiana could be potentially used in the biofortification of nutritive and medicinal qualities of plants.

Leaf-tissue Nutrient Dynamics in Mature Muscadine Cultivars Carlos and Noble in Georgia and North Carolina

More than 3000 acres of commercial muscadine (Vitis rotundifolia) vineyards exist in the southeastern United States. The muscadine wine industry is generating an economic impact of $1 billion in North Carolina alone. Muscadines have been cultivated since the 1800s, but muscadine vineyard fertilizer programs, tissue sampling, and nutrient sufficiency ranges continue to be based on anecdotal knowledge. While seasonal changes in tissue nutrient concentration are well documented in bunch grape (Vitis vinifera), questions remain about the seasonal and cultivar-dependent dynamics of muscadine leaf tissue nutrient concentrations. The aim of this study was to assess temporal and cultivar-related differences in tissue nutrient concentration of mature commercially grown muscadines. Leaf tissue nutrient concentration of the muscadine cultivars Carlos and Noble were assessed in three vineyards (Piedmont North Carolina, north Georgia, and south Georgia) at bloom, véraison, and postharvest in 2018 and 2019. Our results show that nitrogen (N), phosphorus (P), and manganese (Mn) were generally above the recommended sufficiency ranges, with calcium increasing over the season—and N, P, and potassium decreasing over the season. ‘Carlos’ had significantly higher levels of N and P, compared with ‘Noble’, while ‘Noble’ showed higher Mn concentration than ‘Carlos’. With this evaluation, we demonstrate the need for a modification in muscadine tissue nutrient sufficiency ranges that are based on cultivar and vine growth stage.

Physiological responses to salinity among warm‐season turfgrasses of contrasting salinity tolerance

AbstractThere is increasing need to understand physiological mechanisms of warm‐season turfgrass species for potential use in salt‐affected soils due to increased use of recycled water for irrigation in arid and semi‐arid regions. Greenhouse screenings previously conducted during 2014 and 2015 at Texas A&amp;M University, College Station, TX, and determined relative salinity tolerance among 45 experimental genotypes representing four warm‐season turfgrass species under salinity levels ranging from 2.5 to 45 dS m−1. From that study, eight genotypes (two genotypes representing the highest and lowest relative salinity tolerance from each of four species) were advanced for additional evaluations aimed at characterizing physiological responses to salinity in this study. Genotypes included ‘Celebration®’ and ‘UGB79’ bermudagrass (Cynodon spp.), ‘DALZ1313’ and ‘Zeon’ zoysiagrass (Zoysia spp.), ‘UGP3’ and ‘UGP38’ seashore paspalum (Paspalum vaginatum), and ‘Floratam’ and ‘Palmetto’ St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]. Grasses were grown in the greenhouse and sub‐irrigated daily for 4 weeks at salinity levels of 2.5, 15 and 30 dS m−1. Responses including visual turf quality, shoot growth rates, salt excretion rates, root and shoot tissue nutrient concentrations, as well as root and shoot Na:K were characterized. Results showed that all grasses adjusted osmotically under increasing salinity levels. However, differences in Na:K were noted among species, with bermudagrass and seashore paspalum genotypes maintaining proportionally lower Na:K in roots and shoots than zoysiagrass and St. Augustinegrass under salinity stress. Salt excretion rates also increased at increasing salinity in zoysiagrass and bermudagrass, with greater salt excretion observed in the salinity‐tolerant genotypes of each species. The results demonstrate that salt tolerance is complex, and show a variety of salt tolerance mechanisms are employed by these warm‐season species.

Plant derived tissue and soil nutrient concentration for plantations of four conifer species growing under different site and vegetation management conditions

This study investigates the long-term effects of vegetation management on nutrient concentration of various tissues and ecosystem components of 16 to 18 year-old Douglas-fir (DF), western hemlock (WH), western redcedar (WRC), and grand fir (GF) stands growing in Oregon’s central Coast Range (CR) and DF and WRC growing in Oregon’s Cascade mountain foothills (CF) under two contrasting vegetation management (VM) treatments. The treatments consist of: Control, which received no herbicide application post planting, and VM, which received five years of spring release herbicide application. Both treatments include a fall site preparation herbicide application. The ecosystem was broken down into crop trees (separated into foliage, live branches, bark, and stemwood), midstory species (separated into foliage and stem), understory, forest floor, fine roots, and mineral soil (with depth increments 0.0–0.2 m, 0.2–0.4 m, 0.4–0.6 m, and 0.6–1.0 m). All samples were analyzed for concentration of total carbon, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese, sodium, and zinc. This study design resulted in 1,740 unique nutrient concentration results being reported. The effect of VM (treatment) on tissue concentration varied by nutrient, overstory crop species (species), ecosystem component, and site. Forest floor and crop tree bark, followed by fine roots, were the ecosystem component nutrient concentrations that showed the greatest number of treatment effects across all species. Soil concentrations showed large variation across sites but were generally unaffected by treatment and species. At the CR site, magnesium and calcium soil concentrations were higher in VM plots across species, while zinc concentrations were lower. There were no other effects of treatment on soil nutrient concentrations, but there were some significant treatment × crop species interactions. Most notably, at the CF site, the concentration of C and N were higher in VM plots than control plots of DF, while the opposite was true for WRC. While total soil concentrations were generally unaffected by treatment and are unlikely to be adversely affected in the long term, it is possible that VM can reduce soil nitrogen for slow growing species like WRC.

Characterising leaf petiole, blade and bunchstem nutrient concentration across three grapevine cultivars

Background and Aims Tissue nutrient concentration is useful for determining vine nutritional status and managing vineyard nutrition. Current Australian guidelines are based on the analysis of petioles at flowering and leaf blades at veraison, sampled adjacent to the basal inflorescence and bunch. The comparative value of these two tissue types and that of the bunchstem for assessing plant nutrient status at the two phenological stages is required. Moreover, the impact of node position and cultivar is unclear. Methods and Results We characterised the macro and micronutrients at flowering and veraison of three segments of the petiole, the entire leaf blade and the bunchstem at two node positions of cvs Cabernet Sauvignon, Shiraz and Chardonnay grown under identical conditions. Nutrient concentration was non-uniform along the length of the petiole. The middle segment had the lowest concentration of most macronutrients, while Mn was generally highest in the middle segment. When averaged across petioles, blades and bunchstems the lower node had a higher nutrient concentration than the upper node, except for K. The concentration of some nutrients within the leaf blade was correlated with those of the petiole but this was dependent on the cultivar and the time of sampling. The nutrient concentration of the bunchstem was more closely correlated to the petiole than to the blade. Cultivar differences were also apparent, but this depended on the individual nutrient and the sampling time. Conclusions Nutrient concentration was inconsistent along the length of the petiole. The nutrient concentration of petioles, blades and bunchstems was node, cultivar and time specific. Therefore, tissue nutrient analysis will be meaningful only if sampling is consistent across these variables. Significance of the Study These results will aid in the formation of better sampling protocols for accurate grapevine nutrient diagnosis.

Plant productivity and nutrient uptake as affected by tillage and site‐position in furrow‐irrigated rice

AbstractFurrow‐irrigated rice (Oryza sativa L.) is a relatively new production system that has been shown to have increased water‐use efficiency and reduced operational costs. However, due to spatial variations in soil moisture, field studies are necessary to evaluate potential resulting variations in rice growth and yield in the furrow‐irrigated production system. This study was conducted to evaluate the effects of tillage practice (conventional tillage, CT; no‐tillage, NT) and site position (up‐, mid‐, and down‐slope) on aboveground biomass, yield, and plant nutrient uptake from rice grown in a silt‐loam soil in a direct‐seeded, furrow‐irrigated production system in eastern Arkansas. Field research was conducted from May to September during the 2018 and 2019 rice growing seasons. Total aboveground dry matter, vegetative dry matter, and yield were unaffected (P &gt; .05) by tillage treatment or site position in either growing season. Vegetative tissue nutrient concentrations and uptake were generally at least 10% greater (P &lt; .05) under CT than NT but did not substantially differ by site position during the drier growing season (2018). During the wetter growing season (2019), vegetative tissue nutrient concentrations and uptake were generally at least 20% greater (P &lt; .05) at the up‐ than at the mid‐ or down‐slope positions. Results suggest that different approaches, in terms of soil and nutrient management per site position, in combination with tillage practices, may need to be considered for implementation to maximize nutrient uptake and reduce losses, thus improving the agronomic suitability of the furrow‐irrigated rice production system.

Soybean Nutrition in a Novel Single-Nutrient Source Hydroponic Solution

Hydroponic systems are efficient for studying plant nutrition. It is often desirable to adjust individual nutrients for unique species’ needs and/or to create multiple nutrient deficiencies within the same study. However, this is challenging to do with traditional solutions as nutrients are generally added as dual nutrient salts, such as when varying phosphorus (P) concentration also affects nitrogen concentration; potentially, the chemical form of the nutrient taken up when ammonium phosphate is the source for P. This can create unintended consequences with nutrients other than those intended for adjustment. A new hydroponic system has been created to allow for nutrient deficiencies using single-nutrient sources, including ammonium nitrate; phosphoric, sulfuric, hydrochloric, and boric acids; potassium, calcium, magnesium, zinc, and copper carbonates; manganese acetate; sodium molybdate; iron EDDHA; with HEDTA as an additional chelate. This nutrient solution was compared to a traditional “Hoagland” hydroponic solution to grow soybean (Glycine max (L.) Merr). Additional treatments included alteration of pH in the new solution as well as evaluating varying levels of calcium, magnesium, and manganese. This new solution proved effective, as soybean was grown to maturity and performed as well as the traditional Hoagland solution. Adjusting pH downward with hydrochloric acid resulted in healthy plants, but solution pH was not adequately buffered. Adjusting pH with acetic acid resulted in toxicity. Further work is required to provide better pH buffering and approximately align tissue nutrient concentrations with field-grown soybean.

Protocol for salt stress screening of African marigold under hydroponic system

The present study was carried out at ICAR-IARI to standardize the protocol for screening of African marigold against saline stress under hydroponic system. Seedlings of African marigold cv. Pusa Narangi Gainda were grown under hydroponics system. They were treated with different levels of NaCl, viz. 0 mM 50 mM, 80 mM, 100 mM, 120 mM, 140 mM, 150 mM, 160 mM, 200 mM, after 7 days of transplanting to standardize the threshold level for the further rapid screening of germplasms at nursery stage. Observations on mortality, growth, morphological, physiological, biochemical parameters and tissue nutrient status were recorded and found to decrease with increasing in saline stress. Mortality in seedlings was not observed up to 80 m M NaCl stress. 150-160 mM qualified as the indicator concentration for the screening of African marigold genotypes based on the performance of marigold genotypes with regard to different morphological, physiological, biochemical parameters and tissue nutrient contents.

English

Salinity stress negatively affects key physiological phenomena in plants while plants show great variability and respond differentially for tolerance to salt stress. Usually, nutrients imbalances affect specific plant tissues and physiological processes which are requisite for normal plant growth and development. The aim of this two-year (2017 and 2018) simulated field study was to investigate phenotypic plasticity for growth, relative leaf water content (RLWC) and nutrient status in milk thistle [Silybum marianum (L.) Gaertn.] ecotypes and the potential role of soil supplementation with pre-optimized levels of plant growth promoters (PGPs) in modulating these attributes under control and salinity (12 dS/m) stress. Four ecotypes of milk thistle were collected from three ecologically distinct zones including Faisalabad (FSD) and Kalar Kahar (KK) – semi-arid zone, Gujranwala (GUJ) – hot semi-arid zone and Quetta (QTA) – cool semi-arid zone. The studied nutrients were nitrate-N, phosphate-P, sulfate-S, sodium (Na), potassium (K) and calcium (Ca). The soil supplemented PGPs, applied with irrigation water, were ascorbic acid (AsA), thiourea (TU) and moringa leaf extract (MLE) at 250 μM, 500 μM and 3%, respectively of soil moisture content at field capacity. Results indicated that soil supplementation of PGPs in the field conditions is a feasible approach for enhancing nutrient uptake of milk thistle ecotypes under salt stress, while the effect of salinity stress restricted the uptake of the studied nutrients and caused their imbalance. Although the salinity stress reduced shoot and root dry matter, RLWC and restricted the uptake of these nutrients irrespective of ecotypes, the levels of nitrate-N, phosphate-P, K, sulfate-S, Ca, and RWC contents increased more with the soil supplementation of AsA followed by MLE as compared to other soil supplements in both the study years. Among the ecotypes, QTA followed by KK and FSD ecotypes gained more dry weight with greater leaf RWC and higher tissue nutrient contents due to PGPs under salt stress. The principal component analysis and correlation data revealed the existence of distinct phenotypic plasticity in the milk thistle ecotypes for nutrient acquisition with soil supplementation of PGPs under salinity stress. To conclude, ecotypes from QTA and KK were more promising than the others while AsA and MLE were better soil supplements in improving shoot and root nutrients under salt stress. © 2021 Friends Science Publishers

Juncus Bulbosus Tissue Nutrient Concentrations and Stoichiometry in Oligotrophic Ecosystems: Variability with Seasons, Growth Forms, Organs and Habitats.

Aquatic plant nutrient concentrations provide important information to characterise their role in nutrient retention and turnover in aquatic ecosystems. While large standing biomass of aquatic plants is typically found in nutrient-rich localities, it may also occur in oligotrophic ecosystems. Juncus bulbosus is able to form massive stands even in very nutrient-dilute waters. Here we show that this may be achieved by tissues with very high carbon-to-nutrient ratios combined with perennial (slow) growth and a poor food source for grazers inferred from plant stoichiometry and tissue nutrient thresholds. We also show that the C, N, P and C:N:P stoichiometric ratios of Juncus bulbosus vary with the time of year, habitats (lakes versus rivers) and organs (roots versus shoots). We found no differences between growth forms (notably in P, inferred as the most limiting nutrient) corresponding to small and large plant stands. The mass development of J. bulbosus requires C, N and P, whatever the ecosystem (lake or river), and not just CO2 and NH4, as suggested in previous studies. Since macrophytes inhabiting oligotrophic aquatic ecosystems are dominated by isoetids (perennial plants with a high root/shoot ratio), attention should be paid to quantifying the role of roots in aquatic plant stoichiometry, nutrient turnover and nutrient retention.

Suppression of Pratylenchus brachyurus and soybean growth inoculated with arbuscular mycorrhizal fungus

Arbuscular mycorrhizal fungi perform a variety of plant-beneficial processes. including increased resistance to disease. The objective of this work was to study arbuscular mycorrhizal fungus Rhizoglomus clarum effect on phytonematode Pratylenchus brachyurus suppression and on soybean plants growth. Two experiments were performed under greenhouse conditions. First. soybean plants growth was evaluated in mycorrhizal fungi presence and absence. In the second experiment. phytonematode damage in soybean cultivated in mycorrhizal fungi presence and absence was evaluated. During soybean flowering was evaluated mycorrhizal colonization, dry matter, nodulation, chlorophyll and nutrient content in plant tissue, nematodes number in soil and root penetration, and nematode reproduction factor was obtained, R. clarum mycorrhizal colonization reduced by 64% the number of nematodes penetrated in roots and increased soybean plants nodulation, nutrient absorption and dry matter accumulation. The stimulation to mycorrhization is a strategy to reduce damage caused by Pratylenchus brachyurus to soybean plants.

Evidence of elemental homeostasis in fine root and leaf tissues of saplings across a fertility gradient in tropical montane forest in Hainan, China

For plants, elemental nutrients are important belowground resources that sustain growth and survival. To understand how tropical plant nutrient status responds to environmental variation, we asked whether concentrations of nutrients in root and leaf tissues track gradients in soil nutrient concentrations and if tissue nutrient concentrations respond independently or in concert to soil nutrient concentrations. We measured soil nutrient concentrations of rhizosphere soil and root and leaf tissue elemental concentrations of saplings from 14 Angiosperm families in montane tropical forest of Jianfengling, China. Using mixed-effects models, we modeled the nutrient concentration of plant tissues as a function of soil resources. Of fourteen elements measured, seven —nitrogen, boron, phosphorus, potassium, manganese, copper and zinc— increased in concentrations in root and leaf tissues with higher soil nutrient availability; two decreased —aluminum and carbon; three were invariant —magnesium, sulfur, and calcium; and two —sodium and iron— showed contrasting patterns between leaves and roots. Eight elements necessary to leaf physiological function, but also used in root functioning —nitrogen, boron, magnesium phosphorus, sulfur, potassium, calcium, manganese— were more concentrated in leaves than roots. Additionally, most elements showed tradeoffs in concentrations between roots and leaves. Plant lineage (i.e. family) explained very little of the variation about this overall trend. Overall, increases in tissue nutrient concentrations with soil fertility were subtle if present at all. Thus, we conclude that tissue nutrients of juvenile tropical trees have a high degree of elemental homeostasis with local-scale soil nutrient content in Jianfengling.

Responses of sweet pepper (Capsicum annum L.) cultivated in a closed hydroponic system to variable calcium concentrations in the nutrient solution.

The use of water containing calcium bicarbonate (Ca(HCO3 )2 ) at excessively high concentrations in closed hydroponic crops can cause calcium ion (Ca2+ ) accumulation in the recycled nutrient solution (NS) and concomitantly negatively affect yield and product quality. The aim of the study was to determine maximum Ca2+ concentrations that do not harm the crop and to simulate the pattern of Ca2+ accumulation when the Ca2+ concentration in the irrigation water, and concomitantly in the replenishment nutrient solution (RNS), is excessive. In the current study, irrigation water containing 1.5, 3.0, 4.5 and 6.0 mmol L-1 Ca2+ was used to prepare the RNS supplied to pepper cultivated in a closed hydroponic system. At 1.5 mmol L-1 Ca2+ , no Ca2+ accumulation was observed in the recirculating NS. However, at 3.0, 4.5 and 6.0 mmol L-1 in the irrigation water, the Ca2+ concentration in the recirculating NS, increased by the latter cropping stages to 17, 28 and 37 mmol L-1 , corresponding to 6.4, 9.0 and 10.8 dS m-1 . The accumulation of Ca2+ in the recirculating NS affected both tissue nutrient concentrations and uptake concentrations of Ca2+ , sulphate ion (SO4 2- ) and magnesium ion (Mg2+ ), but this was not the case for nitrogen (N) or potassium ion (K+ ). Growth, yield and plant water uptake were restricted at moderate (3.0 and 4.5 mmol L-1 ) and high (6.0 mmol L-1 ) external Ca2+ levels. In soilless pepper crops with zero discharge of fertigation effluents, the Ca2+ concentration in the irrigation water and the RNS should be lower than 3.0 mmol L-1 to avoid yield restrictions due to salinity. © 2021 Society of Chemical Industry.

Control of Meloidogyne paranaensis mediated by silicon

ABSTRACT: The potential of silicon (Si) to control nematodes is often reported in association with the resistance induction mechanism. The objective of this work was to evaluate the hypothesis of resistance induction in plants against nematodes through the application of Si. In vitro experiments were carried out to evaluate the effect of Si and potassium chloride (KCl) on the hatching and mortality of Meloidogyne paranaensis juveniles. For the purpose of a greenhouse experiment, tomato plants were used as a model for bifurcated roots, using the respective control treatments, KCl and distilled water. Ten days after treatment, 2,000 eggs of M. paranaensis were inoculated. At 55 days post-inoculation, the reproduction factor and number of nematodes per gram of root were evaluated. Additionally, the tissue nutrient concentration and gas exchange variables were analyzed. Silicon reduces nematode viability, when in direct contact with the nematode in in vitro experiments and in bifurcated plants. When plants were treated with Si on one side of the root, no nematode control was observed on the opposite corresponding side. Results suggested that Si has a positive effect on the reduction of M. paranaensis population, but probably induced resistance to nematode only through direct action.