Tissue Phosphorus Concentrations Research Articles

Optimizing vertical farm cultivation of Cichorium spinosum L.: White Light's influence and nutrition management

The objective of this study was to examine the integration of a wild leafy vegetable, Cichorium spinosum L., in vertical farms. This research comprises two experiments focusing on different “white” light products and nutrient solutions. During both experiments, the temperature varied between 25 and 28 °C, relative humidity ranged from 50 to 70 %, carbon dioxide was at 450 ppm, and light intensity was set at 300 μmol m−2 s−1 respectively. In the lighting experiment, the three spectra used had the commercial names Neutral, Full and a SunLike™, and their spectral composition (blue:green:red:far-red) were 14:32:43:10, 16:36:40:8, and 21:34:36:7 respectively. The photoperiod was set to 12 h and the plant density was 50 plants m−2. Results showed no significant impact on agronomical parameters and leaf anatomy. The stomatal length and width decreased as the red:blue ratio of the light sources decreased, being greater in the Neutral treatment (red:blue ratio of 3.1) compared to the Full and SunLike™ (red:blue ratios of 2.5 and 1.7 respectively). Based on these results the preferable “white light” product was the one with the highest efficiency and lowest market price at the time of the experiment. In the nutrient solution experiment, the agronomical and nutritional attributes of stamnagathi plants supplied with a control nutrient solution, “N10-Fe15” were compared to plants cultivated under limited nitrogen, “N4-Fe15” and elevated iron, “N10-Fe48”, EC was 1.5 ds m−1, and pH was 5.6–6.5. The experiment simulated commercial practices by increasing the photoperiod to 15 h and plant density to 100 plants per square meter. The results did not demonstrate significant effect of the nutrient solution differences on the agronomical characteristics except from a decrease in total Kjeldahl nitrogen under limited nitrogen conditions. Notably, leaf tissue phosphorus content increased under elevated iron conditions. The nitrate content remained within safe for consumption thresholds for all treatments. Based on these results, stamnagathi can be integrated in vertical farms under limited nitrogen conditions. Stamnagathi's resilience to elevated iron in the nutrient solution demonstrated its potential for future biofortification experiments.

Incident Light Level Influences Elemental Budgets of Serianthes nelsonii Merr. Leaf Development

Recovery efforts for the endangered Serianthes nelsonii have been deficient. To learn more about leaf development costs, the content of biomass and essential elements were determined in the supportive and laminae tissue of leaves that were constructed under different levels of incident light. The biomass required to construct a leaf in 22% light transmission was 65% of that in full sun, and light treatment did not influence the balance between supportive and laminae tissues. Concentrations of carbon, phosphorus, iron, manganese, and boron were greatest for in full-sun laminae, but those of nitrogen, potassium, calcium, magnesium, and zinc were greatest in shaded laminae. The same patterns with regard to light were exhibited in supportive tissues for carbon, nitrogen, potassium, calcium, magnesium, and zinc. In contrast, the supportive tissue phosphorus content was greatest in shaded leaves, and the light level did not influence the supportive tissue concentrations of the remaining elements. The leaf laminae consistently exhibited greater concentrations of elements with the exception of potassium and nickel, which were greater in the supportive tissues. These results indicate that the construction of full-sun S. nelsonii leaves is more costly than that of shaded leaves, and the transfer of biomass and essential elements between the supportive and laminae tissues is not substantially influenced by the developmental light level. Identifying the drivers of S. nelsonii leaf element concentrations is crucial for understanding the role of this charismatic tree in community-level processes.

Phosphorus uptake by macrophyte plants in monocultures and polycultures in constructed wetlands for wastewater treatment

Phosphorus uptake by common and ornamental plants was studied in pilot-scale horizontal subsurface flow (HSSF) constructed wetlands (CWs) with monocultures and polycultures. Three HSSF CWs were planted with monocultures of Phragmites australis (HSSF-Phr), Schoenoplectus californicus (HSSF-Sch) and Cyperus papyrus (HSSF-Cyp), and one polyculture was planted with C. papyrus and Zantedeschia aethiopica (HSSF-Cyp/Zant). During the experimental period, removal efficiency, growth characteristics, biomass production and phosphorus uptake were evaluated in the cold season (fall/winter) and warm season (spring/summer). In general, the cold season showed better performance with an order of HSSF-Cyp/Zant > HSSF-Cyp > HSSF-Sch > HSSF-Phr in the evaluated parameters. The removal efficiencies were 33%, 27%, 23% and 12%, respectively. The biomass production and density of the HSSF treatments ranged from 1.5 to 5.4 kg dry weight (DW)/m2, and 435 to 1298 individuals/m2 with higher values for HSSF-Sch. The tissue phosphorus content was 5 to 20% higher belowground in all plants, including ornamentals. Phosphorus uptake was higher for polyculture (HSSF-Cyp/Zant) and monoculture (HSSF-Cyp) planted with ornamentals, with a mean of 30 g P/m2. Also, the polyculture was not affected by the seasons, reaching up to 27% phosphorus uptake by the plants. According to our results, the ornamental species of the polyculture contribute to the phosphorus uptake.

Species ecological strategy and soil phosphorus supply interactively affect plant biomass and phosphorus concentration

Excess soil phosphorus often constrains ecological restoration of degraded semi-natural grasslands in Western-Europe. Slow-growing species, often target of restoration (measures), are at a disadvantage because they are outcompeted by fast-growing species. Gaining insight into the responses of plant species and communities to soil phosphorus availability will help understanding restoration trajectories of grassland ecosystems. We set up two pot experiments using twenty grassland species with contrasting growth forms (i.e. grasses versus forbs) and nutrient use strategies (i.e. acquisitive versus conservative nutrient use). We quantified the nutrient use strategy of a species based on the stress-tolerance value of the CSR framework (StrateFy et al. 2017). We grew these species (1) as monocultures and (2) in mixtures along a soil phosphorus gradient and measured the aboveground biomass and plant phosphorus concentrations. Plant phosphorus concentration generally increased with soil phosphorus supply and biomass increased with soil phosphorus supply only in conservative communities. Forbs had higher plant phosphorus concentrations compared to grasses both in monocultures and mixtures. The species’ nutrient use strategy had contrasting effects on plant tissue phosphorus concentrations, depending on soil phosphorus supply (interaction effect) and vegetation biomass (dilution effect). Our findings contribute to the knowledge required for successful ecological restoration of species-rich grasslands. Our results suggest that under specific conditions (i.e. nitrogen limitation, no dispersal limitation, no light limitation), slow-growing species can survive and even thrive under excess soil phosphorus availability. In the field, competition by fast-growing species may be reduced by increased mowing or grazing management.

Phosphorus Supply Does Not Affect Fusarium Crown Rot of Winter Wheat

Fusarium crown rot (FCR) is a major limitation to the wheat (Triticum aestivum L.) industry in the inland Pacific Northwest, United States. Genetic resistance to FCR is poorly understood and major gene resistance is not available in adapted cultivars. Chemical control is ineffective and crop rotations, which disrupt cycles of the disease, are not feasible in the region’s precipitation-limited climate. Cultural control methods are the only realistic option for farmers who struggle to minimize the impact of this disease. It is well established that FCR is favored by moisture-limited environments and an oversupply of plant-available nitrogen in soil. Effects of the supply of phosphorus in soil have not been clearly delineated. We conducted a 2-year FCR experiment at two locations in the low-precipitation zone (<30 cm) of north-central Oregon. Phosphorus fertilizer was applied in-furrow with phosphorus (P) at rates of 0, 5, and 15 kg ha−1, to plots planted with either a hard red or soft white winter wheat cultivar. The P at 15 kg ha−1 application rate increased tissue phosphorus concentration, early-season dry matter, and phosphorus uptake at both locations and both years of this study. Phosphorus treatment had no effect on grain yield, protein, or test weight. Phosphorus had no effect on the severity of FCR. This research improved our knowledge of cultural management boundaries as they relate to the control of FCR. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Morpho-physiological and biochemical attributes of Chili (Capsicum annum L.) genotypes grown under varying salinity levels.

Climate change is causing soil salinization, resulting in huge crop losses throughout the world. Multiple physiological and biochemical pathways determine the ability of plants to tolerate salt stress. Chili (Capsicum annum L.) is a salt-susceptible crop; therefore, its growth and yield is negatively impacted by salinity. Irreversible damage at cell level and photo inhibition due to high production of reactive oxygen species (ROS) and less CO2 availability caused by water stress is directly linked with salinity. A pot experiment was conducted to determine the impact of five NaCl salinity levels, i.e., 0,1.5, 3.0, 5.0 and 7.0 dS m-1 on growth, biochemical attributes and yield of two chili genotypes (‘Plahi’ and ‘A-120’). Salinity stress significantly reduced fresh and dry weight, relative water contents, water use efficiency, leaf osmotic potential, glycine betaine (GB) contents, photosynthetic rate (A), transpiration rate (E), stomatal conductance (Ci), and chlorophyll contents of tested genotypes. Salinity stress significantly enhanced malondialdehyde (MDA) contents and activities of the enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). In addition, increasing salinity levels significantly reduced the tissue phosphorus and potassium concentrations, while enhanced the tissue sodium and chloride concentrations. Genotype ‘Plahi’ had better growth and biochemical attributes compared to ‘A-120’. Therefore, ‘Plahi’ is recommended for saline areas to improve chili production.

Biochar and nitrogen application rates alter some forage and soil minerals concentrations and soil leachate quality in a semiarid mixed grassland system

AbstractIn resource‐limited agroclimatic environments such as the semiarid and arid regions of the world, mineral undernourishment has been a major limitation to grazing livestock productivity. A soil amendment that has the potential to increase plant mineral uptake and reduce nutrient losses in grassland systems is biochar. The objective of this study was to evaluate the effects of biochar and nitrogen application rates on forage tissue mineral concentrations, soil constituents and leachate quality in a semiarid environment. Treatments were the factorial combination (3 × 3) of three biochar application rates (0, 8.9 and 17.8 Mg/ha) and three N application rates (0, 80 and 120 kg N/ha) arranged in a randomized complete block design experiment with four replications. Treatment means were considered different p ≤ .05. Forage tissue phosphorus concentration was altered by biochar rate × year interaction and a main effect of N rate. Tissue phosphorus concentration was greater at 17.8 Mg biochar/ ha rate than the 0 and 8.9 Mg/ha rates in 2019. For the N rate effect, forage tissue phosphorus concentration was greatest at 0 kg N/ha rate and lowest at 120 kg N/ha rate. The concentration of potassium in the forage was influenced by a biochar rate × N rate interaction. At 120 kg N/ha rate, tissue potassium concentration was greater at 8.9 and 17.8 Mg biochar/ ha rates than the 0 Mg biochar/ha rate. After three years of evaluation, this study demonstrated that biochar used independently or through its interaction with nitrogen fertilizer or year, had a positive influence on the forage minerals phosphorus, potassium, sodium and manganese and the tendency to also positively influenced the forage sulfur and boron concentrations.

Arbuscular Mycorrhizal Fungi Inoculation Reduced the Growth of Pre-Rooted Olive Cuttings in a Greenhouse

The effect of commercial mycorrhizal fungi on pre-rooted olive cuttings was assessed. The study consisted of two experiments, the first arranged as a factorial design with three cultivars (Cobrançosa, Madural, and Verdeal Transmontana) and three soil treatments (commercial mycorrhizal fungi, zeolites, and control) and the second as a completely randomized design with three treatments (commercial mycorrhizal fungi, sterilized soil, and control). Cobrançosa grew better than the other cultivars, showing good rooting and initial growth features. Mycorrhizal plants showed reduced growth in comparison to those of the untreated control. This result was explained by competition for photosynthates between plant growth and the expansion of fungi hyphae. Cuttings of reduced leaf area and a twin-wall polycarbonate cover of the greenhouse, somewhat opaque to photosynthetic active radiation, may also have contributed to limit the maximum photosynthetic rate and delay the growth of the inoculated plants. Accordingly, in the mycorrhizal pots, the soil organic carbon (C) increased, probably due to the presence of fungi hyphae in soil samples. Zeolites reduced plant dry matter (DM) yield and tissue phosphorus (P) concentration compared to the control, while increasing the availability in the soil of the cations present in their initial composition. Soil sterilization seems to have reduced soil P bioavailability by inactivating soil enzymes. This study showed that the inoculation with mycorrhizal fungi of pre-rooted cuttings can delay their initial growth. Although these plants may be better prepared to grow in the field, in the short term, their lower development can be a problem for the nurseryman.

The maximum growth rate hypothesis is correct for eukaryotic photosynthetic organisms, but not cyanobacteria.

Summary The (maximum) growth rate (µmax) hypothesis predicts that cellular and tissue phosphorus (P) concentrations should increase with increasing growth rate, and RNA should also increase as most of the P is required to make ribosomes.Using published data, we show that though there is a strong positive relationship between the µmax of all photosynthetic organisms and their P content (% dry weight), leading to a relatively constant P productivity, the relationship with RNA content is more complex.In eukaryotes there is a strong positive relationship between µmax and RNA content expressed as % dry weight, and RNA constitutes a relatively constant 25% of total P. In prokaryotes the rRNA operon copy number is the important determinant of the amount of RNA present in the cell. The amount of phospholipid expressed as % dry weight increases with increasing µmax in microalgae. The relative proportions of each of the five major P‐containing constituents is remarkably constant, except that the proportion of RNA is greater and phospholipids smaller in prokaryotic than eukaryotic photosynthetic organisms. The effect of temperature differences between studies was minor.The evidence for and against P‐containing constituents other than RNA being involved with ribosome synthesis and functioning is discussed.

Dietary organic zinc promotes growth, immune response and antioxidant capacity by modulating zinc signaling in juvenile Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted to evaluate effects of dietary organic zinc (zinc amino acid chelate) on growth performance, mineral bioaccumulation in whole body, hepatopancreas and carapace, innate immune response and antioxidant capacity of juvenile Pacific white shrimp Litopenaeus vannamei. Five isonitrogenous and isolipidic diets were formulated to contain different zinc levels of 46.4 (basal diet), 65.5, 85.9, 108.4 and 130.6 mg kg−1. Dietary zinc level significantly influenced growth and feed utilization, with the lowest weight gain and highest feed conversion ratio observed in shrimp fed the basal diet. The optimal dietary zinc requirement was estimated to be 104.8 mg kg-1 for juvenile Pacific white shrimp. Shrimp fed the diet containing 130.6 mg kg−1 Zn had the highest zinc concentration in hepatopancreas and carapace, but there were no significant differences in calcium or phosphorus concentration in tissues. Dietary Zn increased the activities of lysozyme, alkaline phosphatase and polyphenol oxidase in hepatopancreas. Shrimp fed the diets supplemented with zinc had significantly higher activity of Cu/Zn SOD and lower content of malondialdehyde in hepatopancreas. The expression levels of toll, imd, lzm, proPO and alp involved in immunity and Cu/Zn sod related to oxidation resistance were up-regulated. Zinc also promoted the expression levels of mt and mtf-1, and up-regulated the expression of SLC39 family genes (zip3, zip9, zip11, zip14) in hepatopancreas. These data provided novel insights in the potential mechanism of organic zinc-induced enhancement of immunity and antioxidant capacity in Pacific white shrimp.

Manipulating Phosphorus, Calcium, and Magnesium Utilization by Growing Lambs Using Natural Zeolite (Clinoptilolite)

A total of 24 three-month-old lambs with an average weight of 23 ± 1.5 kg were used in this study and fed a complete diet supplemented with natural zeolite at 1% and 2% of feed weight to evaluate the effect of zeolite on calcium (Ca), phosphorus (P), and magnesium (Mg) concentration in tissues (kidney, liver, and muscle), rumen fluid, and blood. Adding zeolite at 2% to the diet resulted in an increase (p < 0.05) in body weight but a depressed feed conversion ratio. Phosphorus digestibility was significantly (p < 0.05) increased with the addition of zeolite while the digestibility of Ca and Mg remained unaffected (p > 0.05). The concentration of Ca, Mg, and P in the liver remained unchanged (p > 0.05) with the addition of zeolite. The addition of zeolite led to a decrease (p < 0.05) in the Ca concentration in the kidney and muscle, whereas the Ca concentration in lambs receiving diets supplemented with 2% zeolite (123.13 and 48.49 µg/g) was significantly (p < 0.05) higher than supplementation at 1% (120.13 and 45.66 µg/g, respectively, for kidney and muscle). Furthermore, serum and rumen fluid concentrations of P, Ca, and Mg exhibited no significant differences upon the addition of zeolite to the diet. Conclusively, diet supplementation by zeolite at 2% improves performance and especially P digestibility, which may result in the reduction in minerals in lambs’ waste and consequently a reduction in environmental pollution.

Selection of bean lineages regarding the use and response to phosphorus available in nutrient solution

The objectives of this work were to evaluate the genetic variability of bean lineages in relation to phosphorus accumulation in plant tissues and yield, in addition to identifying efficient bean lineages in the use of phosphorus and responsive to the application of phosphorus in the crop environment. Work was carried out at Plant Science Department of the Federal University of Santa Maria. Concentrations of phosphorus in the nutrient solution between 1.33 and 1.84 mmol L-1 provide higher dry mass of pods, grains, number of grains and grain yield for the cultivars Pérola and IPR88 Uirapurú in the growing seasons autumn-winter and spring-summer. Concentrations between 1.37 and 1.96 mmol L-1 have the highest values of phosphorus in plant tissues, grain yield and phytic acid. Characteristics dry matter of leaves, stem and pods in pod filling, dry matter of grains on maturation, number of grains, number of pods and phosphorus concentration in plant tissues at the pod filling stage are promising because it allows for indirect selection. The nutritional value of leaves in young plants, for phosphorus, equivalent to that of grains. There is genetic variability among the bean lineages studied, for the production of dry mass, yield and accumulation of phosphorus in the tissues. Lineage L 2527 showed to be efficient and responsive to the use of phosphorus for the shoot of the plant. Lineage L 2225 showed to be efficient in the use of phosphorus in shoot, grains and grain production, besides maintaining this characteristic in the two growing seasons.

Grass–Legume Forage Systems Effect on Phosphorus Removal from a Grassland Historically Irrigated with Reclaimed Wastewater

The utilization of reclaimed wastewater is a suitable and sustainable approach to agriculture production in water-scarce regions. However, even though the wastewater is treated to reduce nutrient concentration such as phosphorus, the 10,600 to 14,006 m3 of water applied ha−1 year−1 on grass and alfalfa hay crops in Nevada can lead to soil phosphorus buildup over an extended period. This study evaluated the effectiveness of forage systems (FS) of monoculture grass, monoculture legume, and their mixtures on herbage accumulation, tissue phosphorus concentration, and quantity of phosphorus removed from a grassland under wastewater irrigation. The study was carried out at the Main Station Field laboratory in Reno, Nevada, USA. A total of 23 FS using tall fescue (Schedonorus arundinaceus (Schreb.) Dumort), alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) in monocultures or grass–legume mixtures (25:75, 50:50, and 75:25) based on seeding rate were used. The response variables were herbage accumulation (HA), tissue phosphorus concentration, and phosphorus removal. Forage systems means were considered different P ≤ 0.05. Herbage accumulation, tissue phosphorus concentration, and phosphorus removal differed among FS and year. Herbage accumulation was similar for the grass monocultures (10.5 Mg ha−1; SE = 1.1) and the majority of the grass–legume mixtures (9.0 Mg ha−1; SE = 1.1) but both systems had greater HA than legumes monoculture (4.3 Mg ha−1; SE = 1.1). The legume monocultures of alfalfa and white clover had the greatest phosphorus concentrations (10.9 g kg−1 dry matter; SE = 0.44) among all FS. Total phosphorus removed was least among legume monocultures (34.0 kg P ha−1; SE = 6.2) in this study and generally similar for grass monocultures (67.4 kg P ha−1; SE = 6.2) and grass–legume mixtures of 75:25 (61.7 kg P ha−1; SE = 6.2). Based on the response variables, agronomic, and environmental considerations a grass–legume mixture that includes 75:25 or even a 50:50 seeding rate ratio will be suitable options for phosphorus removal from phosphorus enriched grasslands in semiarid ecosystems that utilized wastewater for irrigation.

Effect of Glomus fasciculatum On Nutrient Uptake and Growth of a Medicinal Plant, Coleus forskohlii

Aims: Coleus forskohlii Briq. (syn. Coleus barbatus Benth.) belonging to the family Lamiaceae is a well known plant throughout the country and known as ‘pashanbhedi’ in Sanskrit and ‘pathatchur’ in Hindi is one of the most potential medicinal plants of the future, as its pharmacoproperties have been discovered only recently. Its tuberous roots are found to be rich source of forskolin which is being used as a remedy for hypertension, glaucoma, asthma, congestive heart failures and certain types of cancers and also being use as vegetables. In addition, forskolin is reported to have used in the preparation of medicines for controlling body weight, preventing hair greying and restoring normal colour of grey hairs. Its foliage is also employed in treating intestinal disorders and used as a condiment since a long time. Keeping the above views in mind, the present investigation was undertaken to study the influence of an arbuscular mycorrhizal (AM) fungus, G. fasciculatum on phosphorus uptake and growth of Coleus forskohlii.
 Study Design: Various tests or experiments were done in this study. Total leaf tissue phosphorus content was determined following the Microkjeldhal method of Jackson (1973) and chlorophyll estimation was done following the method of Mahadevan and Sridhar (1982) .Root colonization of C. forskohlii by G. fasciculatum was observed by the ‘Rapid clearing and staining technique’ (Phillips & Hayman, 1970). Forskolin content in C. forskohlii tubers was estimated by High performance liquid chromatography (HPLC).
 Place and Duration of Study: Sample: The experiment was carried out in the Department of Botany, Burdwan University. A soil culture of Glomus fasciculatum was propagated as endomycorrhizal species in Zea mays as suitable host in pot culture using sterile sand and soil (pH 5.6; organic carbon 0.6%, P content 45 ppm) in 1:1 ratio. 400 gm of rhizosphere soil with AM-inoculated root fragments of Zea mays was introduced in the dry, loamy, fine-textured soil (pH 5.8; organic carbon 0.6%, P content 45 ppm, total nitrogen 0.03%) of pot culture (2.0 kg of soil per pot) at a depth of 2 inches below the Coleus cutting (12-16 cm long comprising 3-4 pairs of leaves) being planted, between June 2011 and July 2012.
 Results: Responses of an arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum on phosphorus uptake by the plant at different developmental phases have been studied. The result indicates that symbiotic association of mycorrhizal fungus amounts to greater uptake of phosphorus and increased chlorophyll content in AM treated plants than in non mycorrhizal plants which gradually happened to be maintained throughout their developmental stages. Different growth parameters like plant height, root length, no. of roots, no. of leaves, no. of branches, fresh weight of shoot, roots, tubers and forskolin content were significantly higher in AM treated plants than in respective controls.
 Conclusion: The better growth of mycorrhizal plants was attributed to improved nutrient uptake, especially phosphorus. The result suggested that G. fasciculatum is one of the most potentially effective bio-fertilizer of Coleus forskohlii.

Effects of Cowpea-Amaranth Intercropping and Fertiliser Application on Soil Phosphatase Activities, Available Soil Phosphorus, and Crop Growth Response

Low available soil phosphorus (P) is associated with its immobility, which renders it unavailable for plant uptake. In addition, farmers normally apply inorganic fertilisers to legumes to activate soil-bound phosphorus using root exudates. Sufficient soil mineral nutrition is key to sustainable crop production, and hence food and nutritional security. The aim of this study was to quantify the acid and alkaline phosphatase activity as an indicator of P supply and availability under varying levels of nitrogen, phosphorus and potassium (NPK) fertilization and different cropping systems. An intercropping (cowpea and amaranth) and fertiliser (control, 25%, 50%, and 100% of the recommended NPK levels) field trial was laid out in a 2 × 4 factorial treatment structure in a completely randomized design (CRD) with four replications. There was higher acid and alkaline phosphatase activity in the rhizosphere of cowpea and amaranth grown as sole crops compared to those from intercropping. The cowpea and amaranth plants grown without fertiliser or 25% NPK had the highest rhizospheric phosphatase activity, while 100% NPK application exhibited the least. The markedly higher phosphatase activity from the low fertiliser application treatments indicates the possible stimulation of microbial activity to supplement P demands for the crops. The study revealed that the application of lower rates inorganic fertilisers in a legume intercrop stimulates the activity of the phosphatase enzymes, which can subsequently liberate soil-bound phosphorus. Plant tissue phosphorus concentration of cowpea and amaranth plants increased proportionately to the increase in fertiliser application up to 50% of the recommended NPK level. The land equivalent ratio (LER) was greater than 1, indicating that it is more beneficial to intercrop cowpea and amaranth as opposed to growing them as sole crops. Overall, the application of NPK fertilizer to amounts of up to 50%, based on the results of this study, appear to be better than 100% in terms of biomass accumulation and phosphate activity.

Growth benefits provided by different arbuscular mycorrhizal fungi to Plantago lanceolata depend on the form of available phosphorus

Strains of arbuscular mycorrhizal fungi (AMF) differ markedly in the growth benefits they provide to plants. We investigated whether these differences depend on the chemical form of inorganic phosphorus. The closely related AMF Glomus custos and Rhizophagus irregularis were compared using Plantago lanceolata as the host plant, grown in quartz sand with either soluble orthophosphate or sparingly soluble hydroxyapatite as a sole source of phosphorus. In a growth experiment with AMF-inoculated plants in a climate chamber, sampling at 3-wk intervals enabled a detailed time-resolved analysis of shoot and root phosphorus concentrations and growth performance of P. lanceolata. The ability of AMF to enhance plant growth and deliver phosphate depended strongly on the identity of the available phosphorus source. In orthophosphate-amended substrate only modest differences in plant growth performance (dry matter accumulation and allocation, phosphorus acquisition) were observed between the two AMFs, despite evident AMF root colonization as shown by strain-specific mtLSU qPCR analysis. The treatment with hydroxyapatite however, created stringent growth-limiting conditions and significantly increased the growth benefit provided by R. irregularis over G. custos and the non-mycorrhizal treatment. Plants with R. irregularis could acquire much more phosphorus from apatite compared to G. custos. There were also differences in shoot-to-root dry matter allocation and plant tissue phosphorus concentrations between the R. irregularis and G. custos treatments. Our observations suggest that in experiments on the symbiosis between plants and mycorrhizal fungi more attention should be paid to the chemical form of phosphorus in soil.

Plant growth and arbuscular mycorrhizae development in oil sands processing by-products

Soil pollutants such as hydrocarbons can induce toxic effects in plants and associated arbuscular mycorrhizal fungi (AMF). This study was conducted to evaluate if the legume Lotus corniculatus and the grass Elymus trachycaulus and arbuscular mycorrhizal fungi could grow in two oil sands processing by-products after bitumen extraction from the oil sands in northern Alberta, Canada. Substrate treatments were coarse tailings sand (CTS), a mix of dry mature fine tailings (MFT) with CTS (1:1) and Pleistocene sandy soil (hydrocarbon free); microbial treatments were without AMF, with AMF and AMF plus soil bacteria isolated from oil sands reclamation sites. Plant biomass, root morphology, leaf water content, shoot tissue phosphorus content and mycorrhizal colonization were evaluated. Both plant species had reduced growth in CTS and tailings mix relative to sandy soil. AMF frequency and intensity in roots of E. trachycaulus was not influenced by soil hydrocarbons; however, it decreased significantly over time in roots of L. corniculatus without bacteria in CTS. Mycorrhizal inoculation alone did not significantly improve plant growth in CTS and tailings mix; however, inoculation with mycorrhizae plus bacteria led to a significantly positive response of both plant species in CTS. Thus, combined inoculation with selected mycorrhizae and bacteria led to synergistic effects. Such combinations may be used in future to improve plant growth in reclamation of CTS and tailings mix.

Mapping QTLs conferring salt tolerance and micronutrient concentrations at seedling stage in wheat

Soil salinization and degradation is one of the consequences of climate change. Identification of major salt tolerance genes and marker assisted selection (MAS) can accelerate wheat breeding for this trait. We genotyped 154 wheat F2 lines derived from a cross between salt tolerant and susceptible cultivars using the Axiom Wheat Breeder’s Genotyping Array. A high-density linkage map of 988 single nucleotide polymorphisms (SNPs) was constructed and utilized for quantitative trait loci (QTL) mapping for salt tolerance traits and mineral concentrations under salinity. Of 49 mapped QTLs, six were for Na+ exclusion (NAX) and two QTLs (qSNAX.2 A.1, qSNAX.2 A.2) on chromosome 2 A coincided with a reported major NAX QTL (Nax1 or HKT1;4). Two other major NAX QTLs were mapped on 7 A, which contributed 11.23 and 18.79% of the salt tolerance respectively. In addition to Ca+2 and Mg+2 QTLs, twenty-seven QTLs for tissue Phosphorus, Zinc, Iron, Manganese, Copper, Sulphur and Boron concentrations under salinity were also mapped. The 1293 segregating SNPs were annotated/located within genes for various ion channels, signalling pathways, transcription factors (TFs), metabolic pathways and 258 of them showed differential expression in silico under salinity. These findings will create new opportunities for salt tolerance breeding programs.

Trailing Blackberry Genotypes Differ in Yield and Postharvest Fruit Quality during Establishment in an Organic Production System

Four blackberry (Rubus L. subgenus Rubus Watson) cultivars (‘Obsidian’, ‘Black Diamond’, ‘Metolius’, ‘Onyx’) and two advanced selections (ORUS 1939-4 and ORUS 2635-1) were evaluated during the establishment years of an organic production system for fresh market. The planting was established in Spring 2010 using approved practices for organic production and was certified organic in 2012, the first fruiting year. Plants were irrigated using a dripline under a woven polyethylene groundcover (weed mat) installed for weed management. Liquid fertilizers injected through the drip system were used at rates of 56 kg·ha−1 total nitrogen (N) in 2011–12 and 90 kg·ha−1 total N in 2013. Genotypes differed in the level of nutrients measured in primocane leaves. Tissue phosphorus (P), potassium (K), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) concentrations were within the recommended standards, but tissue calcium (Ca), magnesium (Mg), and boron (B) were deficient in some or all genotypes. Although two cultivars and both advanced selections responded well in terms of plant growth and yield to the organic production system used, yields in ‘Onyx’ and ‘Metolius’ were considered low for commercial production. In contrast, the higher yielding ‘Obsidian’ and ORUS-2635-1 appeared to be the best suited for organic fresh market production as a result of larger fruit size, greater fruit firmness, higher sugar-to-acid ratios, lower post-harvest percent moisture loss in ORUS-2635-1, and the longest number of marketable storage days at 5 °C in ‘Obsidian’.

Relationship between tissue phosphorus and seawater phosphate in the brown alga Hormosira banksii

We measured tissue phosphorus content of high and low intertidal Hormosira banksii to test the hypothesis that tissue phosphorus content would be greater in individuals from the low intertidal because of greater total uptake associated with longer immersion in seawater. Moreover, we predicted that tissue phosphorus would be greater at sites where the seawater contained higher phosphate concentrations. There was a positive, linear relationship between local seawater phosphate concentrations and tissue phosphorus content of H. banksii from high and low intertidal zones at six different sites in winter. However, there were no comparable relationships in summer, even though the range of seawater phosphate concentration was similar in both seasons. The phosphorus contents of low intertidal H. banksii were significantly greater than high intertidal H. banksii in winter, but not in summer. Reasons for these differences may be related to greater access to seawater phosphate in low intertidal algae (than those in the high intertidal) in winter, followed by greater utilisation of the internal phosphorus between winter and summer, due to faster growth rates in the low intertidal.