Mineral Nutrient Concentrations Research Articles

P-fertiliser and rhizobial inoculation increased the concentration of mineral nutrients in the rhizosphere of two chickpea genotypes

ABSTRACT Co-application of fertilisers and biofertilisers increases solubility and concentration of nutrient elements in the soil. However, information on the effect of P fertiliser and rhizobium inoculation on the concentration of mineral elements in the rhizosphere of field-grown chickpea in contrasting soil types is lacking. We assessed the effect of phosphorus fertiliser, rhizobium inoculation, and rhizobium inoculation plus P fertilizer on the concentration of nutrients in the rhizosphere of 2 chickpea genotypes (ACC#1 & ACC#5) at clay and sandy soil sites in two consecutive years. ACC#5 accumulated higher amounts of rhizospheric nutrients than ACC#1 in both soil types despite the variable response to fertiliser treatment. Rhizobium inoculation plus P fertiliser resulted in higher accumulations of rhizosphere N (7-219%), P (20-348%), K (9-365%), Ca (2-155%) and Zn (15-259%) compared to the other fertiliser treatments suggesting an additive effect of P fertiliser and rhizobium inoculation. Moreover, the effect of fertiliser treatments was more pronounced in the clay than the sandy soil. Our investigation is the first to document the effects of fertiliser treatment, genotype, and soil type on the accumulation of rhizosphere nutrients in field-grown chickpea. However, we propose further studies, incorporating more cultivars and environments, before making practical recommendations.

Differential responses of bulb quality attributes, mineral nutrient contents, and targeted major metabolites in onion bulbs after long-term commercial cold storage

Differential responses of bulb quality attributes, mineral nutrient contents, and targeted major metabolites in onion bulbs after long-term commercial cold storage

Arbuscular Mycorrhizal Fungi Promote the Degradation of the Fore-Rotating Crop (Brassica napus L.) Straw, Improve the Growth of and Reduce the Cadmium and Lead Content in the Subsequent Maize

Arbuscular mycorrhizal fungi (AMF) are widely present in heavy metal-polluted soils, but their effects on straw degradation and plant growth of rotated crops are poorly understood. In this study, a pot experiment was used to simulate the return of fore-rotating crop (Brassica napus L.) straw to farmland with a subsequent planting of maize in a lead–zinc mining area on the Yunnan Plateau, Southwest China, which included four treatments: control (CK), addition of rape straw (SR), inoculation of AMF (AMF), and both AMF inoculation and straw addition (AMF + SR). The effects of AMF on the degradation and nutrient release of the fore-rotating rape straw and the growth, mineral nutrition and the cadmium (Cd) and lead (Pb) contents of the subsequent maize were investigated. Compared with the CK treatment, AMF significantly promoted the degradation of rape straw and the release of mineral nutrients (nitrogen, phosphorus and potassium) as well as the Cd and Pb, increased the content of available nutrients in soil, and improved the mineral nutrient contents in the maize. AMF + SR significantly increased the maize height and biomass by 32–35% and decreased the available Cd and Pb contents in soil and the Cd and Pb contents in the maize by 20–30% and 18–25%, respectively. Moreover, the available Cd and Pb contents in the soil presented significant positive correlations with their contents in the maize but negative correlations with the height and biomass of the maize. Thus, AMF played an important regulatory role in the nutrient cycling and heavy metal accumulation of the crop rotation.

Effects of walnut/Rosa roxburghii compound planting on growth, fruit yield, quality of Rosa roxburghii and soil properties.

Walnut and Rosa roxburghii are important arbor and shrub fruit trees cultivated in the southwest mountainous area of China. Furthermore, those two species are compound cultivated in this area. In this study, we investigated the growth, yield, fruit quality, photosynthesis, and soil fertility of R. roxburghii in a 7-year typical 'Qianhe 7'/ 'Guinong 5' compound planting pattern in Guizhou. The results showed that compared with the monoculture, photosynthetic pigment content and photosynthetic rate of R. roxburghii leaves were significantly lower in the compound plantation. The growth and yield of R. roxburghii decreased significantly, with a 77.7% reduction of yield. Fruit quality of R. roxburghii was improved. The content of ascorbic acid (Vc), total phenol, carbohydrate, K, Ca, Mg, Fe, Mn, Zn, and other substances increased significantly. Fruit Vc and Mn content increased by 34.1% and 64.1%, respectively. The contents of total N, available N and K in the soil increased by 45.8%, 34.8% and 67.8%, respectively. The abundance of soil microorganisms and functional bacteria increased significantly, with the increase of bacteria and fungi being more than 36.0%. The increase of potassium bacteria and nitrogen fixing bacteria was 71.3% and 124.8%, respectively. However, the contents of organic matter, carbon-nitrogen ratio, total P, total K, available mineral nutrient (P, Ca, Mg, Fe, Mn, Cu, Zn) contents decreased. While the activities of soil urease and catalase were increased, the activities of other soil enzymes (sucrase, cellulase, protease, phosphatase) were significantly reduced. In summary, with continuous growth of walnuts in the walnut/R. roxburghii compound plantation, there was obvious shade and soil fertility competition for R. roxburghii, which affected its yield, but had a improvement effect on fruit quality.

Ecophysiology of Endangered Plant Species Saussurea esthonica: Effect of Mineral Nutrient Availability and Soil Moisture

Saussurea esthonica is an endangered plant species typical for wet inland habitats such as calcareous fens. Due to its limited population size and distribution, non-invasive sampling of is important in the research of S. esthonica. The aim of the present study was to assess the effect of mineral nutrient availability and substrate moisture on the growth, physiological status, and mineral nutrition of S. esthonica. The non-destructive measurement of physiological parameters was performed in native habitats during three vegetative seasons, followed by two experiments in controlled conditions. Soil at the two Estonian sites had a relatively larger similarity in the composition of plant-available mineral nutrients in comparison to the two Latvian sites. The chlorophyll a fluorescence parameter Performance Index correlated with the total precipitation in the respective month before measurement, but no significant relationship with other environmental variables was found. For mineral nutrient experiments, plants were grown in four substrates with different mineral nutrient composition, resembling that of soil at different S. esthonica sites. Plant growth and physiological indices were significantly affected by the mineral composition of the substrate. Differences in leaf and root mineral nutrient concentrations of S. esthonica plants in part reflected differences in substrate mineral concentration. To evaluate the effect of soil moisture on growth and photosynthesis-associated parameters of S. esthonica, plants were cultivated in "Pope+" substrate at four different moisture treatments (dry, normal, wet, and waterlodged). The most intense growth of S. esthonica plants was evident in waterlodged conditions, which decreased with a decrease in soil moisture. The biomass of leaves increased by 106% and that of the roots increased by 72% as soil moisture increased from dry to normal. For waterlodged plants, leaf biomass increased by 263% and root biomass increased by 566%, in comparison to that for plants cultivated in dry substrate. Substrate drying had a more negative effect on the growth of S. esthonica plants in comparison to that of waterlodging, and this can be directly linked to prevalent hydrological conditions of an alkaline fen habitat native to the species. Therefore, the preservation of the natural water regime in natural habitats is critical to the conservation of the species.

Willow (Salix babylonica) Extracts Can Act as Biostimulants for Enhancing Salinity Tolerance of Maize Grown in Soilless Culture

Salinity negatively affects agricultural production by reducing crop growth and yield. Botanical biostimulants can be used as innovative and sustainable tools to cope with abiotic stress. In this study, salicylic acid (SA) (25 µM) and willow leaf (WL) (0.1 and 0.2%) and bark (WB) (0.1 and 0.2%) extracts were applied as plant-based biostimulants to hydroponically grown maize in the absence and presence of salinity stress (60 mM NaCl). The hormone-like activity and mineral composition of willow extracts were analyzed, and the effects of willow extracts on growth parameters, chlorophyll content, antioxidative enzyme activities, protein levels and mineral nutrient concentrations of maize plants were measured. Within the tested biostimulant applications, 0.2% WB, 0.1% WL and 0.2% WL gave the most promising results, considering the stress alleviating effects. The shoot biomass was increased up to 50% with 0.1% WL treatment and Na+ uptake was reduced with biostimulant applications under saline conditions. Under stress, the protein concentrations of maize leaves were enhanced by 50% and 80% with high doses of WB and WL applications, respectively. Results indicate that willow tree prunings can be valuable bio-economy resources, and aqueous extracts prepared from their leaves and barks can be used as effective and eco-friendly biostimulants.

Concentrations of plant mineral nutrients and potentially toxic elements in some medicinal plants in the Asteraceae, Fabaceae, and Lamiaceae families from Southern Türkiye: insights into health implications

Medicinal plants have been used throughout history in the treatment of many diseases in traditional Anatolian folk medicine as well as all over the world. The rapid increase in agricultural and industrial activities due to the increasing population around the world causes air, water and soil pollution, and accumulation of potentially toxic elements in medicinal plants. In this study, plant mineral nutrients and potentially toxic elements analyzes were carried out in 38 plant species belonging to the medicinally important families Asteraceae, Fabaceae and Lamiaceae. The percentage of macroelements (in %) varies between 0.20 and 1.46 for calcium, 0.08 and 1.35 for potassium, 0.04 and 0.24 for magnesium, 0.01 and 0.34 for sodium, while concentrations of microelements and potentially toxic elements (in mg kg−1) vary between 3.21 and 721.28 for aluminum, 41.33 and 231.01 for boron, 0.01 and 0.61 for cadmium, 1.09 and 47.79 for chromium, 12.90 and 43.13 for copper, 17.75 and 1109.39 for iron, 51.50 and 715.48 for manganese, 0.12 and 9.42 for nickel, 1.58 and 22.11 for lead and finally 80.82 and 260.08 for zinc. In addition, estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) for potentially toxic elements, and Recommended Dietary Allowance (RDA) values for mineral nutrients were calculated. In some samples in industrial and mining areas, accumulation of some potentially toxic elements was slightly above the permissible limits set by the World Health Organization (WHO). In Summary, the importance of collecting medicinal plants from protected areas such as mountainous rural areas, far from mining, close to clean rivers, and regular control of values with potentially toxic elements analyzes for human health has been understood once again.

Divergent responses of leaf mineral nutrient concentrations among plant families and functional groups to nitrogen addition and irrigation in a semi-arid grassland

Divergent responses of leaf mineral nutrient concentrations among plant families and functional groups to nitrogen addition and irrigation in a semi-arid grassland

The decline of plant mineral nutrition under rising CO2: physiological and molecular aspects of a bad deal.

The elevation of atmospheric CO2 concentration has a strong impact on the physiology of C3 plants, far beyond photosynthesis and C metabolism. In particular, it reduces the concentrations of most mineral nutrients in plant tissues, posing major threats on crop quality, nutrient cycles, and carbon sinks in terrestrial agro-ecosystems. The causes of the detrimental effect of high CO2 levels on plant mineral status are not understood. We provide an update on the main hypotheses and review the increasing evidence that, for nitrogen, this detrimental effect is associated with direct inhibition of key mechanisms of nitrogen uptake and assimilation. We also mention promising strategies for identifying genotypes that will maintain robust nutrient status in a future high-CO2 world.

Multi-elemental and Strontium-Neodymium Isotopic Signatures in Charred Wood: Potential for Wood Provenance Studies

Abstract The chemical composition of the wood reflects the composition of the soil over which the corresponding tree has developed. Multi-elemental and isotopic signatures, which are characteristic of the soil and underlying rock substrates, are potentially powerful tools for determining wood provenance. These tracers are of special interest for charred archaeological wood because they circumvent some limitations of dendrochronological provenancing linked to tree-ring loss. However, thermal degradation may introduce a significant bias in wood chemical and isotopic analyses. This experimental study focused on the effects of carbonization temperature on three geochemical wood markers: elemental signatures and isotopic signatures of strontium and neodymium (86Sr/87Sr and 143Nd/144Nd, respectively). Wood specimens from a variety of oak trees and stand locations were pyrolyzed at four temperatures (ranging from 200°C to 800°C) and analyzed using ICP-MS and μ-XRF (X-ray fluorescence) spectroscopy for elemental composition and with multiple collection ICP-MS (MC-ICP-MS) for strontium (Sr) and neodymium (Nd) isotope composition. The concentration of mineral nutrients generally increased with temperature, but the magnitude of the enrichment depended on the element, wood compartment (sapwood vs. heartwood), and geological substrate. The concentrations of rubidium, strontium, manganese, magnesium, potassium, and, to a lesser extent, calcium, were minimally affected by temperature, wood compartment, and substrate. The ratios between the concentrations of these elements, as well as the 86Sr/87Sr and 143Nd/144Nd isotope ratios, were stable over the entire temperature range. However, only 86Sr/87Sr and selected elemental ratios (calcium or magnesium normalized to manganese) were successful for site discrimination. Therefore, our multi-tracer approach provides promising new information to determine the provenance of charred archaeological wood.

Combining ability and heterosis studies for grain iron and zinc concentrations in pearl millet [Cenchrus americanus (L). Morrone

Iron (Fe) and zinc (Zn) deficiency has been identified as a major food-related health issue, affecting two billion people globally. Efforts to enhance the Fe and Zn content in food grains through plant breeding are an economic and sustainable solution to combat micronutrient deficiency in resource-poor populace of Asia and Africa. Pearl millet, Cenchrus americanus (L). Morrone, considered as a hardy nutri-cereal, is the major food crop for millions of people of these nations. As an effort to enhance its grain mineral content, an investigation was conducted using line × tester analysis to generate information on the extent of heterosis, gene action, combining ability for grain yield potential, and grain mineral nutrients (Fe and Zn). The partitioning of variance attributable to parents indicated that the lines and testers differed significantly for the traits studied. For most of the attributes, hybrids that were superior to the parents in the desired direction in terms of per se performance were identified. The analysis of combining ability variance indicated the preponderance of both additive and non-additive genetic effects. Thus, reciprocal recurrent selection can be used to develop a population with high-grain Fe and Zn contents. The Fe and Zn content in grain exhibited a highly significant and positive association between them, whereas the Fe and Zn contents individually showed a negative, albeit weak, correlation with grain yield and a moderate positive relation with grain weight. This indicates that mineral nutrient contents in grains can be improved without significant compromise on yield. The consistency of these trends across the environment suggests that these findings could be directly used as guiding principles for the genetic enhancement of Fe and Zn grain content in pearl millet.

Spirulina Supplements as a Source of Mineral Nutrients in the Daily Diet

Spirulina is a microalga cultivated in many countries. It is a source of valuable protein, polyunsaturated fatty acids, vitamins, antioxidants and elements. We have not found studies that address the effect of supplement form or cultivation method on the mineral content of spirulina supplements. The aim of this study was to determine whether supplement form (tablet and powder) and cultivation method (organic and conventional) of spirulina have a bearing on the mineral nutrients content. Such an approach accounts for the innovation of our research. The material used in the study was spirulina in tablets and powder form, marketed as a dietary supplement. Samples were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). In turn, selenium (Se) content was determined by spectrofluorimetry. Overall, in terms of mean values, the most abundant mineral in spirulina supplements was phosphorus (P) (15,149 mg/kg) and the least abundant was Se (0.31 mg/kg). Our findings show that both supplement form and cultivation method affect the mineral content of spirulina. Supplements in powder form had a significantly higher content of important elements, such as iron (Fe) (673 mg/kg), magnesium (Mg) (4151 mg/kg) and potassium (K) (16,686 mg/kg), while at the same time containing significantly less sodium (Na) (9868 mg/kg). In terms of the cultivation method, organic spirulina supplements turned out to be a richer dietary source of Fe (703 mg/kg) and K (14,893 mg/kg). In turn, conventionally grown supplements had higher contents of calcium (Ca) (11,269 mg/kg), phosphorus (P) (16,314 mg/kg) and strontium (Sr) (47 mg/kg). Spirulina can therefore be a valuable addition to the daily diet, helping people to achieve the required intake of micronutrients.

The Physiological and Molecular Responses of Exogenous Selenium to Selenium Content and Fruit Quality in Walnut

To study the effect of exogenous selenium on fruit quality in walnut (Juglans regia L.), 8-year-old walnut (Qingxiang) was taken as the research object. In the fruit expansion stage, 300 mg/L of sodium selenate, yeast selenium and sodium selenite solutions were applied on the leaf of walnut, and the selenium levels in leaves, pericarp and kernel were determined at the ripening stage. The fruit quality, mineral nutrient content, antioxidant enzyme activity, and related genes’ expression were analyzed. The results showed that the three exogenous selenium increased the selenium levels in leaves, pericarp and kernel of walnut. They also significantly increased fruit and kernel weights, and kernel linoleic acid, but markedly decreased kernel crude fat and saturated fatty acid. Selenium spraying promoted the absorption of mineral nutrients such as potassium and zinc, but inhibited the absorption of calcium, and had no significant effect on iron and magnesium in the kernel. Three exogenous selenium increased the activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT) significantly in the kernel. Except for sodium selenate treatment significantly reduced malondialdehyde (MDA) content in the kernel, the other two selenium sources treatments had no significant effect on MDA and hydrogen peroxide (H2O2) levels. They also increased the expression of JrCu/Zn-SOD, Jr2-Cys POD, JrCyt-APX and JrCAT in kernel, to different extents. These implies that, in the walnut fruit enlargement period, the foliar spraying selenium could increase the selenium content of walnut, affect the mineral nutrient absorption, improve the antioxidant capacity and related genes’ expression, and reduce the degree of peroxide, and then improve the quality of fruit. Furthermore, yeast selenium showed the comprehensive effect of the best.

The Impact of Different Drying Temperatures on Black Ginger Slices in Relation to Different Applications of Growing Media

Black ginger (Kaempferia parviflora Wall. Ex. Baker) or “halia hitam” in Malay has been traditionally used as health-promoting herbs in relieving body pains, allergies, gastrointestinal disorders, and fungal infections. Recently, black ginger has increased attention from many researchers to identify its medicinal value to treat diseases. In line with that, the objective of the study is to determine the impact of drying temperatures of black ginger rhizomes slices on the different applications of growing media. The experiment was arranged in a complete randomized design with two factors viz. i) different growing media [cocopeat, cocopeat+rice husk biochar, cocopeat+palm kernel shell biochar, cocopeat+sugarcane bagasse biochar, and cocopeat+coconut shell biochar] and ii) two different drying temperature (50 °C & 75 °C) with three replications. The postharvest parameters were total phenolic compound (TPC), total antioxidant (TA), water activity (Aw), and mineral nutrients content. In conclusion, rhizomes planted in Cocopeat+600g biochar substrates such as sugarcane bagasse, rice husk, palm kernel shell, and coconut shell could be suggested as effective growing media for black ginger cultivation under fertigation system and continued with 75 °C drying temperatures without adversely affecting the postharvest quality of black ginger.

Influence of potassium on mineral content, yield and quality attributes of dragon fruit (Selenicereus monacanthus) in acidic soil of Eastern tropical region of India

Production of quality fruits has always been the priority for ensuring better nutrition and market value. Considering the role of potassium in fruit quality improvement a study was carried out in dragon fruit under open field condition during 2020 and 2021 in the eastern tropical climatic condition of India. The treatments comprised viz., K-absentia as control (T1), K 50 g hill−1 year−1 (T2), K 100 g hill−1 year−1 (T3), K 200 g hill−1 year−1 (T4), K 300 g hill−1 year−1 (T5), K 400 g hill−1 year−1 (T6) and K 500 g hill−1 year−1 (T7). Application of K @300 g hill−1 year−1 exhibited the maximal acquisition of minerals such as N, P, K, Mg, Fe, Mn, Zn, Cu in shoot and fruit pulp of dragon fruit. However, calcium did not exhibit a discernible trend. However, excessive dose of K (500 g hill−1year−1) resulted in declination in mineral acquisition. K 300 g hill−1 year−1 (T5) also demonstrated enhanced absolute fruit growth rate, maximal yield, marketable yield, fruit weight, color attributes, bio-chemical attributes such as TSS, carbohydrate, reducing sugar (∼20%), protein, citric acid, ascorbic acid content (∼2 times). Additionally, the same treatment also manifested an enhancement in biochemical attributes such as betacyanin (∼2.2 times), total phenol (∼55%), total flavonoid (∼2.7 times), α-amylase and sucrose synthase activities, and antioxidative property (FRAP activity). Principal component analysis (PCA) illustrated the maximal proximity of most of the variables (quality attributes and mineral nutrient contents) with T5 (K 300 g hill−1 year−1), exemplifying it as the best representative of all the studied variables.

Effect of exogenous selenium on mineral nutrition and antioxidative capacity in cucumber (Cucumis sativus L.) seedlings under cadmium stress

The ameliorative effects and its mitigation mechanisms of selenium (Se) on cadmium (Cd) toxicity in cucumber seedlings were studied through hydroponic experiments. Cd and other mineral nutrient concentrations, antioxidant enzyme activities, and antioxidant contents in cucumber were studied. The results revealed that exogenous Se significantly decreased the Cd concentrations in all tissues, especially in the leaves. Moreover, exogenous Se (Cd + Se) could increase Zn, Na, leaf Cu, stem/root Fe, stem/root Ca, and stem/root Mg concentrations; and reduce leaf Mg concentration, compared with Cd alone treatment. Additionally, the application of Se ameliorated the toxicity of Cd by harmonising the activities of antioxidase, such as Cd + Se treatment reduced Cd-induced increase of superoxide dismutase, glutathione peroxidase, leaf/stem ascorbate peroxidase (APX) activities, which resulted in the significant decrease of the content of hydrogen peroxide, and malondialdialdehyde; increased root APX, and glutathione reductase activities. In addition, the content of nonenzymatic antioxidants such as root-reduced glutathione and oxidised glutathione was significantly increased by adding Se under Cd stress. Also, exogenous Se enhanced the total antioxidant capacity in terms of cupric-reducing antioxidant capacity and decreased total phenols, flavonoids, and leaf/root proline contents under Cd stress. In general, 3 μmol/L Se was conducive to plant growth and improved the cucumber’s ability to alleviate Cd stress.

Mineral nutrient content of soil and roots of Solanum paniculatum L.

Solanum paniculatum L., a species endemic to tropical America and used in folk medicine in the treatment of anemia, hepatic and digestive disorders, has been widely studied. However, to date, no previous studies on correlations between the contents of mineral nutrients in plant roots with their contents in soil have been reported. The aim of this study was to determine the main mineral nutrients found in S. paniculatum roots and the soil in their natural habitat. It was observed that S. paniculatum roots grow in soils rich in calcium and had a positive correlation in the concentration of Ca with Fe, Na and K and a negative correlation with Zn and Mg. The results contribute to the knowledge of mineral nutrients in S. paniculatum as well as to its cultivation.

Single and combined toxicity of polystyrene nanoplastics and arsenic on submerged plant Myriophyllum verticillatum L.

The contamination of nanoplastics (NPs) and heavy metals (HM) in water bodies has caused widespread concern, while their effects on submerged plants are poorly reported. Polystyrene nanoplastics (PSNPs) and arsenic (As) were used to assess their toxicity on Myriophyllum verticillatum L. via the orthogonal experiments. PSNPs significantly reduced the accumulation of As (17.24%–66.67%) in plant. Single As and high As-PSNPs treatments significantly inhibited plant growth, with a maximum reduction of 70.09% in the growth rate. The mineral nutrient content was significantly affected by PSNPs and As treatments. The antioxidant system was significantly inhibited, which was more pronounced in the roots. Similar findings were observed for soluble protein and soluble sugar. Some organic acids and amino acids showed down-regulation at high concentrations of As, leading to a decrease in the content of the mineral element and down-regulation of antioxidant enzyme synthesis. Furthermore, PSNPs could alleviate As toxicity under 0.1 mg/L As treatment but exacerbate As toxicity at 1 mg/L As dose. This study has important implications for the study of submerged plants exposed to co-contamination of microplastics and heavy metals, as well as the possible ecological risk assessment in freshwater.

Toward the replacement of conventional fertilizer with polyhalite in eastern China to improve peanut growth and soil quality

Abstract Background Polyhalite fertilizer application is an effective way to alleviate a shortage of potassium. This study explored the effects of polyhalite fertilizer application as a total or partial replacement for conventional potassium fertilizer to improve peanut growth and soil quality. Results The index of peanut yield and its economic benefits, the content and distribution of mineral nutrients in different organs, soil chemical properties, and rhizosphere microbial diversity in response to the treatments were examined. The results show that the M4P6T treatment (60% polyhalite fertilizer replacing potassium chloride as the base fertilizer, and 40% potassium chloride fertilizer applied as a topdressing) increased profit by 7.2% without affecting the yield. The M4P6T treatment significantly improved the accumulation and distribution of potassium, calcium and magnesium in the kernels compared with the M10B treatment (no polyhalite fertilizer; potassium chloride fertilizer only as the base fertilizer). Soil treated with polyhalite fertilizer had higher alpha-diversity values and greater relative abundance of microbes at the phylum and genus levels. Conclusions Partial substitution of polyhalite for potassium chloride improved soil quality and peanut growth more than did single applications of polyhalite and potassium chloride. Graphical Abstract

Mineral Nutrients, Physiological Disorders, Postharvest Water Loss, and PR Gene Expression in Bell Pepper (Capsicum annuum L.) Fruit under Shade Nets

Abstract Shade nets can be an effective technology for producing bell pepper (Capsicum annuum L.) under hot climatic conditions. However, the effects of shading on fruit quality are still unclear. The objectives were to evaluate the effects of shade level on fruit mineral nutrient content, physiological disorders, and postharvest water loss. Trials were conducted in the spring–summer of 2016, 2017, and 2018 in Tifton, Georgia, USA, following a randomized complete block design with five shade levels: 0% (open field), 30%, 47%, 63%, and 80%. Shading increased the bell pepper fruit dimensions (length, diameter, and weight) in 2016 and mineral nutrient content in 2017. Fruit sunscald incidence decreased with increasing shade level, while blossom-end rot showed inconsistent responses. Postharvest fruit water loss and transpiration rates were highest in fruits from the unshaded treatment in 2016; there were no differences in fruit water loss among the shade levels. NONEXPRESSOR OF PATHOGENESIS-RELATED 1 (NPR1) and PATHOGENESIS-RELATED 1 (PR1) genes expressed more than 1.5-fold and 10-fold, respectively, at 47% shade level compared to 80%, though not significantly. Therefore, plants grown under shading had fruit with greater size, increased mineral nutrient content, and reduced sunscald incidence compared with the unshaded control.