Unveiling The Potential Tolerance And Physiological Responses Mechanisms of Wheat (Ningmai 16) After Exposure to Nickel In a Soil-plant System

Nickel (Ni) accumulation in soils could lead to critical risks to plants, animals and humans. This study aims to unveil the adverse impacts of Ni on wheat Ningmai 16 and toxicity tolerance mechanisms. Lipid peroxidation was significantly facilitated under high Ni stress, mainly reflecting the notable accumulation of malondialdehyde followed by the increase in glutathione-S-transferase (GST) activities. High Ni contamination caused the decrease in chlorophyll content, with the remarkable inhibition of root activity. Transmission electron microscopy (TEM) micrographs further confirmed the toxicity of Ni and provided significant supporting evidence for the accumulation and localisation of Ni in wheat. The mechanisms adopted in alleviating the oxidative damages induced by Ni were revealed by increasing the soluble sugar and proline content, and inducing the GST related gene expression. Additionally, the cell-wall thickening and vacuole compartmentation were also produced in wheat for improving the tolerance of Ni. Finally, most of biochemical parameters indicated a clearly positive or negative relationship with the available Ni contents, and they are proved as good biomarkers to predict the bioavailability of Ni in a soil-wheat system. We believe that our concluding findings would open a new window for a deeper understanding of ecological risks of an often-underestimated element Ni in future endeavors.

Organic Amendment and Mulching Enhanced the Growth and Fruit Quality of Squash Plants (Cucurbita pepo L.) Grown on Silty Loam Soils

Adoption of suitable organic fertilizers and soil mulching are useful tools to enhance soil quality, which will inevitably lead to improved growth and yield of crops. Little is known about the soil organic amendments and Azolla (Azolla pinnata) under soil organic mulching on the growth and yield of squash plant (Cucurbita pepo L.). A comparative study mainly focused on the impacts of organic fertilizer treatments on soil fertility and squash growth under wheat straw mulch was conducted on wooden boxes filled with silty loam soil. Wheat straw, as an organic mulch, and five organic-fertilization treatments were added to the soil. Wheat straw with a size of <2 cm was added to the soil surface with a 2 cm thickness. The fertilization treatments were: control (CO), chemical fertilizer (CF), compost (CT), vermicompost (VC), and dry Azolla (DA). Wheat straw mulch had positive effects on the soil properties, growth, and yield. The maximum fruit yield was obtained from the soil fertilized with DA under wheat straw mulch, while the lowest one was found in the control without mulching. Azolla and organic fertilizers showed a remarkable superiority over the mineral fertilization in increasing the soil fertility as well as the growth and quality of squash fruits; this superiority increased under the wheat straw mulching system. The application of recommended mineral fertilization (CF), compost (CT), vermicompost (VC), and dry Azolla (DA) under wheat straw mulch increased the soil available-N by 2, 20, 12, and 29%, respectively, above the control (CO), while these organic fertilizers without mulching increased the soil available-N by 11, 32, 26, and 48%, respectively. The production of vegetable crops such as squash plants requires the addition of organic fertilizers and mulching to increase yield and quality of fruits.

Selenium in wheat from farming to food

Selenium (Se) plays an important role in human health. Approximately 80% of the world's population does not consume the recommended Se levels. Wheat is an important staple food and Se source for most people in the world. This article summarizes literatures about Se from 1936 to 2020 to investigate Se in wheat farming soil, wheat, and its derived foods. Selenium fortification and the recommended Se level in wheat were also discussed. Results showed that Se contents in wheat farming soil, grain, and its derived foods were 3.8–552 (mean, 220.99), 0–8,270 (mean, 347.30), and 15–2,372 (mean, 211.86) μg ·kg-1, respectively. Selenium content could be increased by leaf Se fertilizer application, and the contents in grain, flour, and its derived foods could be improved from 93.94 to 1,181.92, 73.06 to 1,007.75, and 86.90 to 587.61 μg ·kg-1 in average. Both Se content in farming soil and grain, foliar Se fertilizer concentration rate and grain Se increased rate showed significant linear relationship. The recommended Se fortification level of wheat in different countries was calculated in China, India, and Spain, with recorded values of 18.53–23.96, 2.65–3.37, and 3.93–9.88 g ·hm-2, respectively. Thus, suitable Se fortification in farming effectively improved Se content in wheat grain and its derived foods. Appropriate milling processing and food type are also important factors to be considered to meet people's Se requirement by wheat.

MYCOLOGICAL ASSESSMENT OF WINTER WHEAT FROM AREAS OF THE RE-PUBLIC OF TATARSTAN

Mycological analysis showed that fungi of the genus Fusarium – 33 %, Penicillium – 17 %, Aspergillus – 10 %, Alternaria – 13 %, Trichoderma – 11 %, Mucor – 12 %, yeast fungi – 6 % were most distinguished. The importance in the symbiotic habitat of filamentous fungi depends on the presence of pH, salts, and mineral fertilizers in the soil. In the Vekhneuslonskiy district, loamy soil predominates, the sprouts of winter wheat growing along the roads were distinguished by a weak root system and single seedlings (soil pH – 7,15±0,7). In the Kaibitskiy Buinskiy districts (in the chernozem soil) – wheat germs were strong, the fibrous root system was strengthened, the pH of the soil in the Kaibitskiy region was 6,35±0,4, in Buinskiy – 6,63±0,8. In mycological analysis, the highest indicator of the total number of fungi (TPG) was recorded in the Verkhneuslonsky region – 19,6х103±0,12 to 25,1х103±0,11, mainly fungi of the genus Fusarium were isolated. In the Kaibitsky district, the HPG was: (12,8х103±0,14 to 20,1х103±0,08) fungi of the genus Aspergillus, Fusarium were isolated. In the Buinsky district, the TPG was: (11,4х103±0,14 to 22,2х103±0,10), the fungi Rhizopus spp, Trichoderma spp. Fusarium. There was a correlation between the indicators of TPG and pH: the more acidic the environment, the less TPG. The growth and development of moldy fungi is not affected by the content of nitrates in the soil, so the content of nitrates in soil samples from the Verkhneuslonsky district was 2,8±0,006, Kaibitsky – 3,2±0,011 to 5,60±0,018, Buinsky 3,10±0,010 to 3,2±0,012.

Bioavailability and toxicity variation of benzo[a]pyrene in three soil-wheat systems: Indicators of soil quality

Benzo[a]pyrene (B[a]P) as a representative polycyclic aromatic hydrocarbons is concerned by global scientists in various fields, but its biological and biochemical actions in soil-wheat systems are still rarely reported. The B[a]P as a ubiquitous soil pollutant possesses varied contents in real environment, and herein was studied in systems of soil and wheat to obtain relative results to reveal their variations in different systems. Its bioavailability (extractability and bioaccumulation) and basic biological toxicity were tested based on three typical soil types (red, black, and brown) in China and spiked amounts (0.1, 1, and 10 mg/kg) with several orders of magnitude. Results showed that B[a]P concentrations in soil-wheat systems extracted by HPCD were insignificantly (p > 0.05) higher than Tenax-TA, and varied with soil types and spiked concentrations. Besides, the root and shoot length were mostly inhibited, in a range of -21.85%-26.35% and -0.48%-54.85%, respectively, by B[a]P in different soil types and increased with its increasing concentration. Comparatively, higher bioconcentration factor and translocation factor values were observed under lower group in red soil-wheat systems, and higher spiked groups in black and brown soil-wheat systems. Moreover, inhibitive effects posed by B[a]P were mainly targeted at wheat shoots in these soils. The simultaneous studies provided a comparable knowledge of B[a]P in ecosystems of different soil types combined with different plant species due to lots of variations, further to serve for contaminated soil remediation and sustainable agricultural management.