Shoot Biomass Of Wheat Research Articles

Enhanced phosphorus availability and cadmium remediation using phosphate-solubilizing bacteria-loaded biochar in contaminated soils

Phosphate-solubilizing bacteria (PSB) have garnered extensive attention for their ability to improve soil phosphorus (P) availability and their potential applications in bioremediation. However, the efficacy of PSB is contingent upon their colonization in soils, which can be hindered by the toxicity of heavy metals such as cadmium (Cd). Utilizing biochar as a protective carrier for PSB presents a promising strategy to address this challenge. This study investigated the effects of PSB-loaded biochar on soil P pools and wheat (Triticum aestivum L.) growth under Cd-contaminated conditions. Results indicated that biochar loading facilitated the colonization and functioning of the inoculated PSB strain (Bacillus subtilis), as evidenced by increased soil cultivatable PSB abundance and phosphatase activity as well as increased relative abundance of Bacillus in bacterial community. Consequently, improved soil P availability and reduced soil exchangeable Cd content were observed, leading to a 30.3% increase in wheat shoot biomass, a 50.4% increase in P accumulation, and a 24.1% reduction in Cd accumulation in wheat shoots under the PSB-loaded biochar treatment. Significant shifts in bacterial community composition were revealed by 16S rRNA amplicon sequencing and enhanced microbe-mediated metabolic activities were observed, as demonstrated by soil enzyme assays and metabolome analysis. Overall, these findings underscore the potential of PSB-loaded biochar to enhance P availability, mitigate Cd toxicity, and shape the soil microbial community, offering a promising strategy for sustainable nutrient management and bioremediation in Cd-contaminated agricultural soils.

Unveiling influences of metal-based nanomaterials on wheat growth and physiology: From benefits to detriments

Metal-based nanomaterials (MNs) are widely used in agricultural production. However, our current understanding of the overall effects of MNs on crop health is insufficient. A global meta-analysis of 144 studies involving approximately 2000 paired observations was conducted to explore the impacts of MNs on wheat growth and physiology. Our analysis revealed that the MN type plays a key role in influencing wheat growth. Ag MNs had significant negative effects on wheat growth and physiology, whereas Fe, Ti, and Zn MNs significantly increased wheat biomass and photosynthesis. Our study also observed a clear dose-specific effect, with a decrease in wheat shoot biomass with increasing MN concentrations. Meanwhile, MNs with small sizes (<25 nm) have no significant impacts on wheat growth. Furthermore, both the root and foliar applications significantly improved wheat growth, with no considerable differences. Using a machine learning approach, we found that the MN type was the main driving factor affecting wheat shoot biomass, followed by MN dose and size. Overall, wheat growth and physiology can be negatively influenced by specific MNs, for which a high dose and small size should be avoided in practical applications. Therefore, our study can provide insights into the future design and safe use of MNs in agriculture and increase the public acceptance of nano-agriculture.

Lignin-rich extracts as slow-release coating for phosphorus fertilizers

Lignin (L) is the most abundant three-dimensional polymer with versatile yet attractive structural features and chemical properties for applicability as a coating. The properties of lignin are mainly related to its botanical origin, structure and extraction method. Although there has been a lot of interest in using lignin in fertilizing systems, only limited attempts have been dedicated to studying the effect of the lignin structure and origin on the release of P fertilizer. Thus, the aim of this work was to study the effect of lignin polymers, extracted from different plant biomass, as coating materials for P fertilizers. Thus, the effect of the structural features originating from the botanical origin on the properties of coated fertilizers and their slow release were established. To this end, three lignocellulosic biomass, namely olive pomace (OP), barley straw (BS) and wood shavings (WS) were used as feedstock to extract lignin polymers. Those chemical compositions and thermochemical properties were characterized prior to their application as coating for triple super phosphate (TSP) fertilizer. Coated fertilizers were characterized for their morphology and coating thickness prior to their evaluation as slow release P-based fertilizer. A distinct slow P release behavior was reported for lignin-coated fertilizers with TSP@L-OP being the slowest as compared to TSP@L-WS, TSP@L-BS as well as pristine TSP, which confirm that the botanical origin and most likely the chemical structures of lignin has significant impact on the properties of the coating materiel. A 100 % release of P from the uncoated TSP was observed after 3 days, while the released amount ranged from only 16.9 % for TSP@L-OP up to 33.4 % for TSP@L-BS. The impact of these coated fertilizers on nutrients uptake and wheat growth was also scrutinized and an noticeable improvement of wheat shoot biomass was observed with the coated TSP treatments reaching up 57.8 % for TSP@BS, 78.1 % for TSP @WS and 93.7 % for TSP @OP, compared to uncoated TSP. This was concomitant to a slight increase of P concentration in shoots, roots and rhizosphere soil, which confirmed the positive effect of slow release P fertilizers on plant growth.

Metabolite profiling for model cultivars of wheat and rice under ozone pollution

As essential source for human consumption, plants of wheat and rice are highly sensitive to ozone (O3), resulting in significant agricultural losses under O3 pollution. According to our results, photosynthesis and shoot biomass of wheat and rice were significantly reduced under elevated O3. The activities of SOD, POD and CAT were responsive to O3 pollution in two crops. However, little is known about the effects of elevated O3 concentration on their metabolite profiling. The response of metabolites to elevated ozone was investigated in model cultivars of wheat and rice. A total of 172 compounds significantly changed in seedlings of wheat (103) and rice (89) under O3 pollution. The strong up-regulation of phospholipids and markedly declined of fatty acids were detected in wheat and rice under elevated O3. Methylerythritol 4-phosphate pathway was altered in both crops with reduced accumulation of carbon compound terpene under O3 stress. Meanwhile, O3 treatment led to the high levels of aspartate-derived asparagine or aspartate, which regulated carbon and nitrogen metabolism. Additionally, O3 suppressed the generation of environmental stress-related flavonoids and cinnamic acids via shikimate pathway in the two crops. Moreover, the biosynthesis of sterols was suppressed and isocitrate was not changed under ozone fumigation in wheat, while both of them were increased in rice. The metabolic results reveal the involvement of O3-related metabolites in photosynthesis, oxidative stress and carbon/nitrogen balance. Our findings provide valuable information for understanding of ozone's effects on the physiology and metabolite profiling of crop plants, boosting efforts to screen genetic resources for valuable traits to adapt to O3 pollution.

Effect of slow‐release nitrogen on the nitrogen availability in an andisol and the critical nitrogen concentration in wheat

AbstractThe use of coated fertilizers and the concept of the critical N dilution curve are alternatives capable of improving the production efficiency of wheat (Triticum aestivum L.) crops in agro‐ecosystems. The objectives of this work were to evaluate the effect of a slow release urea‐coated fertilizer on (i) the production of wheat's shoot biomass at the anthesis stage, (ii) the concentration of N in the shoot biomass, and (iii) the N availability in the Andisol. Two fertilizers: urea and urea‐coated were evaluated using four increasing N rates and a control treatment (without fertilization), in three application strategies, during two growing seasons (late sowing [S1] and early sowing [S2]). Samples of shoot biomass and soil (0–20‐cm depths) were collected at five wheat growth stages (Z21, Z31, Z39, Z45, Z69 on the Zadoks scale). The average production of shoot biomass was 10.3 t dry matter (DM) ha–1 for S2 and 7.9 t DM ha–1 for S1 and N concentrations was between 1.0–3.0%. When using a coated urea fertilizer in this Valdivian agro‐ecosystem, no statistical differences (P &lt; .05) in shoot biomass or wheat N concentrations were found at anthesis (Z69). Differences were principally between seasons. We therefore proposed a new adjustment to the dilution N curve, with a value concentration critical, Nc start of 3.80%, and 4.15%, for S1 and S2, respectively. Use demand parameters such as Nc adjusted to the agro‐ecosystem for wheat crop, allows to rationalize the fertilization according to inorganic N available from the soil.

Comparison of wheat growth-response to endophytic Beauveria bassiana (Hypocreales: Cordycipitaceae) derived from an insect versus plant host

Beauveria bassiana (Hypocreales) is a cosmopolitan entomopathogen, infecting &gt;700 insect species. Although traditionally associated with insects, endophytic colonisation of plants is also known. Endophytism may protect plants against insects/diseases and enhance plant growth. Both insect- and plant-derived (endophytic) ‘sources’ of B. bassiana may be present in an agroecosystem, both of which may be in contact with plants. Here, growth response, viz., root length, shoot height, fresh root biomass, fresh and dry shoot biomass of wheat, Triticum aestivum L. (Poaceae), is reported following inoculation with B. bassiana (strain PPRI 7598). The strain was passaged and re-isolated from an insect (IN) versus plant (PL) substrate. When five wheat cultivars were inoculated with either B. bassiana PPRI 7598IN or -PL isolates through seed imbibition, a significantly higher level of endophytism (roots, stems and leaves, combined) was recorded with 7598IN (29.74%) compared to 7598PL (26.13%). Cultivar Baviaans responded best to endophytic colonisation (plant parts combined) at 33.54%, followed by Tugela (31.34%), Kariega (27.87%), Gariep (25.67%) and Elands (21.28%). On average, B. bassiana-treated plants showed a 71% growth increase over control plants. In topically sprayed bioassays, 7598IN caused 57% mortality to Russian wheat aphid, Diuraphis noxia, compared with 50% by 7598PL; also recording a significantly shorter mean time to aphid mortality (4.14 days) versus 7598PL (4.58 days). A significantly higher level of overt mycosis (58.2%) was noted with 7598IN compared with 7598PL (47.9%). Results underscored several positive aspects associated with endophytic B. bassiana in wheat, creating new and exciting IPM possibilities.

Water stress history and wheat genotype modulate rhizosphere microbial response to drought

Different crop genotypes and soils with different water stress histories are known to harbour different microorganisms, but their relative effect on the response of plant-associated microbes to water stress is not known. In a pot experiment, four wheat genotypes (two with recognized drought resistance and two without) were grown in semi-arid soils with different irrigation histories (irrigated and non-irrigated soils) and exposed to four levels of soil water content (ranging from high to low). After one month of exposure to different soil water contents, we examined plant biomass as well as a general (CO2 production) and a specialized (soil uptake of atmospheric H2) functional processes in the rhizosphere. We further measured the abundance of bacteria and fungi in the rhizosphere using real-time PCR. Wheat shoot biomass was lower when growing in non-irrigated soils under low water content. In contrast, under moderate water contents wheat grown in non-irrigated soils had a significantly higher root biomass compared with those grown in irrigated soils. CO2 production did not differ between genotypes and soil irrigation histories under low soil water content. However, we found significantly higher H2 oxidation rates under low water content in the rhizosphere of plants growing in formerly irrigated soil as compared to those grown in formerly non-irrigated soils, although the intensity of the change was genotype-specific. Bacterial abundance was more sensitive to decreasing soil water content than fungal abundance and was mainly influenced by soil water stress history. Taken together, our results highlight that wheat breeding history and soil water stress history differentially influence crop growth performance, a specialized and a general rhizosphere processes, and rhizosphere bacterial and fungal abundance in the face of decreasing soil water content.

Phytotoxicity of soilborne glyphosate residues is influenced by the method of phosphorus fertiliser application

Glyphosate use has increased in recent decades with the adoption of minimum tillage techniques and the emergence of glyphosate-tolerant crop cultivars. There is evidence that glyphosate residues are common in cropping soils at sowing, but any potential impact of these residues on crop growth is not known. This study aimed to determine concentrations of soilborne glyphosate that are phytotoxic to common crop species and investigate any interactions between glyphosate residues and phosphorus (P) fertiliser. A pot study examined the impact of soilborne glyphosate residues on the growth of wheat (Triticum aestivum L.) and narrow leaf lupin (Lupinus angustifolius L) seedlings in a sandy soil with a low P buffering capacity in the absence or presence of P fertiliser applied as a liquid to the topsoil. A second pot study investigated whether the phytotoxic effects of soilborne glyphosate residues on lupin growth in the presence of P fertiliser could be mitigated by banding the P fertiliser (as superphosphate) as per standard practice by farmers. Wheat was more tolerant of glyphosate residues than lupin, with glyphosate levels up to 14.8 mg kg−1 having no effect on wheat shoot growth at 48 days after sowing (DAS), while lupin shoot growth at 48 DAS had an ED10 (i.e. a 10% yield reduction) of glyphosate at 6.4 mg kg−1 in the absence of P fertiliser. When P fertiliser was applied, wheat shoot biomass had an ED10 of 5.8 mg glyphosate kg−1 soil while lupins had an ED10 of 3.4 mg glyphosate kg−1 soil. When P fertiliser (superphosphate) was banded at sowing, lupins grown adjacent to band were unaffected by glyphosate whereas the shoot weights of lupins planted above the band were significantly reduced by 68% in soil containing 1.3 mg kg−1 glyphosate and 81% in soil containing 3.4 mg kg−1 glyphosate. Where P fertiliser was applied, growth reductions in lupin seedlings were observed at soil glyphosate concentrations that have been observed in farmers’ fields, suggesting that glyphosate residues may be problematic in sandy soils with low P buffering capacities. Banding of P fertiliser exacerbated, rather than mitigated, the phytotoxicity of glyphosate residues to lupins where P fertiliser was banded directly beneath the seed.

Augmentation of the phosphorus fertilizer value of biochar by inoculation of wheat with selected Penicillium strains

Due to uncertainty about the accessibility, amount and quality of the remaining phosphate rock stocks, a replacement of mineral phosphorus (P) fertilizers by sustainable alternatives is desirable. One possibility is to use P rich biochar derived from pyrolysis of organic wastes such as sewage sludge; however, plant P availability is usually reduced in thermally treated products. This study aimed to increase the plant availability of biochar-P by means of phosphate-solubilizing microorganisms (PSM). The solubilization profiles of four Penicillium strains for biochar-P and for calcium, iron and aluminum phosphate were determined in liquid cultures containing each respective P source. The pH, soluble P and organic anion (OA) production were measured in the culture filtrate at the end of the incubation. Subsequently, two efficient Penicillium strains were selected to investigate if the observed in vitro P solubilization could benefit wheat growth in pot experiments. The Penicillium strains differed in their ability to solubilize the four P sources and in their OA production pattern. Addition of individual major OAs to Penicillium-free liquid suspensions showed that especially citrate was closely associated with solubilization of biochar-P. Under semi-sterile soil conditions, the inoculated P. aculeatum established well and this fungus significantly increased both wheat shoot biomass and P content in the biochar-amended treatments. These results open up for new approaches using P-solubilizing Penicillium fungi to increase the fertilizer value of P-rich biochar.

Selenium promotes sulfur accumulation and plant growth in wheat (Triticum aestivum).

Selenium (Se) is an essential micronutrient for animals and humans and a target for biofortification in crops. Sulfur (S) is a crucial nutrient for plant growth. To gain better understanding of Se and S nutrition and interaction in plants, the effects of Se dosages and forms on plant growth as well as on S level in seven wheat lines were examined. Low dosages of both selenate and selenite supplements were found to enhance wheat shoot biomass and show no inhibitory effect on grain production. The stimulation on plant growth was correlated with increased APX antioxidant enzyme activity. Se forms were found to exert different effects on S metabolism in wheat plants. Selenate treatment promoted S accumulation, which was not observed with selenite supplement. An over threefold increase of S levels following selenate treatment at low dosages was observed in shoots of all wheat lines. Analysis of the sulfate transporter gene expression revealed an increased transcription of SULTR1;1, SULTR1;3 and SULTR4;1 in roots following 10 μM Na2 SeO4 treatment. Mass spectrometry-based targeted protein quantification confirmed the gene expression results and showed enhanced protein levels. The results suggest that Se treatment mimics S deficiency to activate specific sulfate transporter expression to stimulate S uptake, resulting in the selenate-induced S accumulation. This study supports that plant growth and nutrition benefit from low dosages of Se fertilization and provides information on the basis underlying Se-induced S accumulation in plants.

The importance of water-soluble carbohydrates in the theoretical framework for nitrogen dilution in shoot biomass of wheat

Breeding for yield has increased the concentration of reserve water-soluble carbohydrates (WSC) in wheat from dry, low yielding environments of Australia to wet, high-yielding environments of the UK. This generalized increase in WSC can reduce the concentration of nitrogen (N) in shoots and consequently reduce the crop critical N concentration (%Nc: the minimum concentration of N to achieve maximum growth rates). This may cause errors when assessing a crop’s N status using N dilution curves which relate critical N concentration (%Nc) and shoot biomass (W), i.e. %Nc=aW−b. Inaccurate diagnosis of a crops N status will have negative environmental and economic consequences such as N losses to the environment and yield gaps. Here, we (i) outline the drivers of variation in WSC, (ii) discuss the implications of WSC on wheat N status, (iii) propose an adjustment of the theoretical N dilution framework that makes explicit a WSC compartment, and (iv) provide estimates of the range of error derived from the current two-compartment model.

Switchgrass Biochar Effects on Plant Biomass and Microbial Dynamics in Two Soils from Different Regions

Biochar amendments to soils may alter soil function and fertility in various ways, including through induced changes in the microbial community. We assessed microbial activity and community composition of two distinct clayey soil types, an Aridisol from Colorado (CO) in the U.S. Central Great Plains, and an Alfisol from Virginia (VA) in the southeastern USA following the application of switchgrass (Panicum virgatum) biochar. The switchgrass biochar was applied at four levels, 0%, 2.5%, 5%, and 10%, approximately equivalent to biochar additions of 0, 25, 50, and 100 t ha−1, respectively, to the soils grown with wheat (Triticum aestivum) in an eight-week growth chamber experiment. We measured wheat shoot biomass and nitrogen (N) content and soil nutrient availability and N mineralization rates, and characterized the microbial fatty acid methyl ester (FAME) profiles of the soils. Net N mineralization rates decreased in both soils in proportion to an increase in biochar levels, but the effect was more marked in the VA soil, where net N mineralization decreased from −2.1 to −38.4 mg kg−1. The 10% biochar addition increased soil pH, electrical conductivity, Mehlich- and bicarbonate-extractable phosphorus (P), and extractable potassium (K) in both soil types. The wheat shoot biomass decreased from 17.7 to 9.1 g with incremental additions of biochar in the CO soil, but no difference was noted in plants grown in the VA soil. The FAME recovery assay indicated that the switchgrass biochar addition could introduce artifacts in analysis, so the results needed to be interpreted with caution. Non-corrected total FAME concentrations indicated a decline by 45% and 34% with 10% biochar addition in the CO and VA soils, respectively, though these differences became nonsignificant when the extraction efficiency correction factor was applied. A significant decline in the fungi:bacteria ratio was still evident upon correction in the CO soil with biochar. Switchgrass biochar had the potential to cause short-term negative impacts on plant biomass and alter soil microbial community structure unless measures were taken to add supplemental N and labile carbon (C).

Impact of quality and quantity of biochar and hydrochar on soil Collembola and growth of spring wheat

The effects of biochar (maize biochar – MBC, wood biochar – WBC) and unfermented or fermented hydrochar (HTC) on the euedaphic Collembola Protaphorura fimata and on spring wheat were investigated in greenhouse experiments. The impact of char type, amount of fermented HTC, and MBC-Collembola interactions were assessed. Generally, shoot and root biomass as well as abundance of P. fimata were not affected by the different chars. However, with increasing amounts of fermented HTC the abundance of P. fimata declined, whereas shoot biomass of wheat increased. Moreover, MBC altered root morphology and resulted in thicker roots with higher volume. The latter was not apparent when Collembola were present.

Comparison of Organic and Inorganic Amendments for Enhancing Soil Lead Phytoextraction by Wheat (Triticum aestivum L.)

Phytoextraction has received increasing attention as a promising, cost-effective alternative to conventional engineering-based remediation methods for metal contaminated soils. In order to enhance the phytoremediative ability of green plants chelating agents are commonly used. Our study aims to evaluate whether, citric acid (CA) or elemental sulfur (S) should be used as an alternative to the ethylene diamine tetraacetic acid (EDTA) for chemically enhanced phytoextraction. Results showed that EDTA was more efficient than CA and S in solubilizing lead (Pb) from the soil. The application of EDTA and S increased the shoot biomass of wheat. However, application of CA at higher rates (30 mmol kg−1) resulted in significantly lower wheat biomass. Photosynthesis and transpiration rates increased with EDTA and S application, whereas these parameters were decreased with the application of CA. Elemental sulfur was ineffective for enhancing the concentration of Pb in wheat shoots. Although CA did not increase the Pb solubility measured at the end of experiment, however, it was more effective than EDTA in enhancing the concentration of Pb in the shoots of Triticum aestivum L. It was assumed that increase in Mn concentration to toxic levels in soil with CA addition might have resulted in unusual Pb concentration in wheat plants. The results of the present study suggest that under the conditions used in this experiment, CA at the highest dose was the best amendment for enhanced phytoextraction of Pb using wheat compared to either EDTA or S.

Pseudomonas cepacia and Pseudomonas putida as winter wheat inoculants for biocontrol of Rhizoctonia solani

Pseudomonas cepacia R55 and R85 and Pseudomonas putida R104, antagonistic towards plant pathogenic fungi in vitro, were assessed as seed inoculants for winter wheat (cv. Norstar) grown in a growth chamber in soil infested with Fusarium solani or Rhizoctonia solani isolate AG-1, AG 2-1, or AG-3. Infestation of soil with R. solani AG-1 or AG 2-1 reduced root dry weight of uninoculated plants by 62 and 78%, respectively, whereas R. solani AG-3 or F. solani had no effect on plant biomass. Pseudomonad inoculants increased (relative to plants subjected to disease) the winter wheat root dry weight by 92–128% and shoot dry weight by 28–48% in the soil infested with R. solani AG-1. The shoot material of all plants inoculated with pseudomonads also had significantly (P &lt; 0.05) higher total Fe contents than the uninoculated treatment in the R. solani AG-1 infested soil. Pseudomonas cepacia R55 produced the highest (P &lt; 0.01) total Fe contents in the shoots, but it had no effect on N and P content. Pseudomonas cepacia R85 significantly increased total N (P &lt; 0.05) and total P (P &lt; 0.01) of wheat shoots, and P. putida R104 increased the percentage (P &lt; 0.05) and (or) total P content (P &lt; 0.01) in the soil infested with R. solani AG-1. Pseudomonas cepacia R85 also significantly (P &lt; 0.05) increased wheat shoot biomass in R. solani AG-3 infested soil. All three pseudomonads produced fluorescent siderophores when cultured in a low-iron medium. These results suggest an in situ antibiosis activity of three fluorescent pseudomonad strains towards phytopathogenic fungi and suggest that the plant growth response was probably due to protection against damage caused by R. solani. Key words: biocontrol, pseudomonads, Rhizoctonia solani, winter wheat, siderophores.