Luiz R G Guilherme

• PhD in Crop and Soil Science & Environ. Toxicology
• Professor (Full) at Federal University of Lavras

Rice (Oryza sativa L.) is a crucial crop for biofortification that is widely consumed and is cultivated in soils with low levels of selenium (Se) and zinc (Zn). The study evaluated how upland rice genotypes can increase Se and Zn in grains with foliar fertilization and analyzed the impact on agronomic characteristics and protein and amino acid cont...

Selenium (Se) is essential for humans and other animals and beneficial to plants. However, high Se concentrations cause toxicity in living organisms. Arbuscular mycorrhizae are a symbiotic interaction between arbuscular mycorrhizal fungi (AMF) and plants that can alleviate metal phytotoxicity. This study used synchrotron X-ray fluorescence (S-XRF)...

This study aimed to examine the effects of foliar Se and I applications on chemical and sensory characteristics of blackberry (cv. BRS-Tupy) and raspberry (cv. Heritage) fruits.

This study aimed to improve broccoli seedlings' cold stress tolerance by priming them with selenium (Se) and iodine (I). Different doses of selenium (0, 25, 50, and 75 mg L−1) and iodine (0, 50, 100, 250, and 500 mg L−1) were applied individually and in combination, totaling 21 treatments. After foliar spraying of Se and I, the seedlings were expos...

Cacao cultivation is an important economic and social activity for tropical regions worldwide. Elevated cadmium (Cd) concentrations in soil and cacao beans have become a serious concern for producers and consumers, particularly following the implementation of stricter Cd limits for cacao products in the European Union since 2019. Cadmium is a poten...

Biochars have emerged as a sustainable technology for converting waste into high-value, stable carbon products. Depending on its properties, biochar can retain various elements, including nitrogen (N) as ammonium (N-NH4⁺). This study aimed to evaluate the rapid retention of N-NH4⁺ in biochars produced from coffee husk (CH) and chicken manure (CM) a...

Common beans are an essential food source worldwide, particularly in developing countries, and are grown in soils poor in selenium (Se), a mineral essential for human health. Adding Se to fertilizers is a promising technique; however, more studies are needed on the efficacy of this technique on common beans. This study aimed to evaluate the biofort...

The portable X-ray fluorescence (pXRF) spectrometry has been very useful for the characterization of different earth materials, and its application for foliar analysis is really promising. The performance of pXRF for foliar analysis depends on several factors such as concentration of the elements, fluorescence yield which is influenced by atomic nu...

Venation patterning, orchestrated by auxin, plays a critical role in the evolution of vascular functions, resulting in enhanced hydraulic conductance and photosynthetic rates. Recent studies questioned the well-discussed established protagonism of polar auxin transport in venation development, suggesting that vascular differentiation is governed by...

Waste pile substrates from Fe mining may carry potentially toxic elements (PTE). Rehabilitation efforts must maintain soil vegetation cover effectively, avoiding the dispersion of particulate matter and reducing the risk to the environment and human health. Therefore, this study aims to evaluate the pseudo-total and extractable contents, perform ch...

Abiotic stresses significantly disrupt plant physiology at the molecular, biochemical, and morphological levels, often causing irreversible damage. To ensure sustainable coffee production, it is essential to understand how environmental stresses—such as drought, heat, excess light, and salinity—affect plant growth, and to develop strategies to miti...

Selenium (Se) is an essential element for humans. However, much of the world’s human population is deficient in this element, which has become a public health problem. This study aimed to evaluate whether applying severe water stress to wheat plants (Triticum aestivum L.) could allow Se to reduce the production losses and increase the grain quality...

Investigating the ability of non-hyperaccumulator plants to grow in soils polluted by cadmium (Cd) and their potential for phytostabilization or phytoextraction is essential for assessing their use in phytomanagement efficiency. Therefore, we evaluated the tolerance of high-biomass grasses to Cd by measuring biomass production and element accumulat...

Brazil has made notable advances in soil mapping compared to other Latin American countries, driven by collaborative efforts from federal agencies, research institutions, and universities. However, detailed soil maps remain limited, particularly at local scales. This study explored soil spatial variability in a coffee plantation located in the Braz...

The present study aimed to evaluate the effects of soil Se application in wheat (Triticum aestivum L.) plants grown under a water deficit imposed during the flowering phase. The experiment was conducted under greenhouse conditions at the Federal University of Lavras in the State of Minas Gerais, Brazil. The statistical design was randomized blocks...

Urea is the primary source of nitrogen (N) used in agriculture. However, it has a high N loss potential through volatilization. Various mechanisms can be employed to reduce N volatilization losses by inhibiting urease. When added to urea, iodine (I) has high potential for this purpose. Thus, this study aimed to determine whether adding I to urea re...

Selenium (Se) is a nutrient whose daily intake is often below the recommended levels in people. Biofortification with Se is a method to increase this intake by raising the Se concentration in tomato fruits, an effect dependent on sources and modes of application. Additionally, Se application can promote the enhancement of other compounds in tomato...

Water deficit impacts plant growth and development, causing physiological disturbances that trigger oxidative stress. As an alternative, exogenous application of a sort of molecule can minimize these damages and reduce productivity losses. The iodine (I) supplementation has shown considerable benefits to stressed plants. Nevertheless, there are no...

The rupture of the Fundão dam (Mariana, Brazil) resulted in various environmental and socio-economic impacts on riverside communities. However, the effects of iron mining tailings on the cultivation of vegetables and annual crops still need to be clarified, especially regarding the bioavailability of potentially toxic elements (PTEs), which may be...

Proximal sensors combined with X-ray diffraction (XRD) have optimized soil characterization, but scarce studies have focused on predicting the contents of minerals under this scope. The objectives herein were to: a) use the portable X-ray fluorescence (pXRF) spectrometry, diffuse reflectance spectroscopy in the range of visible and near-infrared (V...

Rare earth elements (REEs) have been intentionally used in Chinese agriculture since the 1980s to improve crop yields. Around the world, REEs are also involuntarily applied to soils through phosphate fertilizers. These elements are known to alleviate damage in plants under abiotic stresses, yet there is no information on how these elements act in t...

Purpose of Review This review examines recent publications on rare earth elements (REE) in soils, critically evaluating their role as emerging soil contaminants. We emphasized new findings and main gaps using a previous review paper published in 2016 by our research group as a reference point. Three major subjects were prioritized: (1) sources, bac...

Fertilization with nickel (Ni) can positively affect plant development due to the role of this micronutrient in nitrogen (N) metabolism, namely, through urease and NiFe-hydrogenase. Although the application of Ni is an emerging practice in modern agriculture, its effectiveness strongly depends on the chosen application method, making further resear...

Much progress has been made in understanding the conditions of biochar production related to biochar properties and carbon (C). Still, very little knowledge has been gained regarding the effects on nitrogen (N), one of the most critical nutrients affected by pyrolysis temperature (PT). Analysis of N in biochar is costly, and alternative methods sho...

Laboratory ecotoxicological tests are important tools for the management of environmental changes derived from anthropogenic activities. Folsomia candida is usually the model species used in some procedures. However, this species may not be sufficiently representative of the sensitivity of the other collembolan species. This study aimed to evaluate...

Selenium is beneficial to plants and is essential for animals and humans, which justifies any efforts for producing Se-enriched wheat grains worldwide. This study aimed to (i) verify if wheat is an efficient species to be used for Se biofortification in tropical agroecosystems and (ii) assess the influence of Se on the physiological and biochemical...

Heavy metals can play an important biological role as micronutrients but also as potentially toxic elements (PTEs). Understanding the natural concentrations of PTEs-Pb and Zn included-in soils allows for the identification and monitoring of contaminated areas and their role in environmental risk assessment. In this study, we aim to determine semito...

Shepherds intentionally burn certain high Andean grasslands to stimulate the regrowth of grass. Nevertheless, this practice results in the generation of Polycyclic Aromatic Hydrocarbons (PAHs), which contaminate and can leach into the soil and be absorbed by plants. Ultimately, this adversely affects the livestock graze on these contaminated plants...

We proposed an accurate pXRF matrix-matched calibration method for the elemental analysis of ground-roasted coffee as well as the corresponding spent coffee grounds (SCG).

A water deficit can negatively impact fruit yield and quality, affecting critical physiological processes. Strategies to mitigate water deficits are crucial to global food security. Iodine (I) may increase the efficiency of the antioxidant system of plants, but its role against water deficits is poorly understood. This study aimed to evaluate the e...

Novel technologies help to monitor the environmental impact of human activities, but tests involving datasets from several countries, encompassing a large variability of soil properties, are still scarce. This study utilized proximal sensors to predict soil organic carbon (OC) and soil texture of samples from Brazil, France, India, Mozambique, and...

Applications of metal-based nanomaterials for the remediation of heavy metal (HM) contaminated environments are of great importance. The ability of metal oxide-based carbon aerogel composite to immobilize HMs in multi-metal contaminated soils has not yet been investigated, particularly under acidic conditions. Herein, we investigate the performance...

This study aimed to investigate the role of Se supply in improving osmotic stress tolerance in coffee seedlings while also evaluating the best timing for Se application. Five times of Se foliar application were assessed during induced osmotic stress with PEG-6000 using the day of imposing stress as a default, plus two control treatments: with osmot...

IntroductionThe by-product of the intermediate process of tanning (BPIPT) can be used in the manufacturing of environmentally-friendly organo-mineral fertilizers (OMF). However, the presence of potentially toxic elements (e.g., chromium, Cr), can hinder the use of BPIPT in agriculture. This study aimed: i) to evaluate soil chemical and biological p...

The ora-pro-nobis (Pereskia aculeata) is a nutritious native American vegetable that stands out for its high protein content. This study aimed to assess the potential of P. aculeata for selenium (Se) biofortification and accumulation by evaluating agronomic parameters, nutrients, and nutritional composition under different forms and application rat...

Drought stress has been considered a major problem in coffee crops, and the higher occurrence of unpredictable environmental events has highlighted the vulnerability of agricultural systems. Several reports have indicated selenium (Se) as a plant biostimulant against environmental stress, including drought. The effects of Se in plants are related t...

Water deficit inhibits plant growth by affecting several physiological processes, which leads to the overproduction of reactive oxygen species (ROS) that may cause oxidative stress. In this regard, iodine (I) is already known to possibly enhance the antioxidant defense system of plants and promote photosynthetic improvements under adverse condition...

Background and Aims In soybean production systems, increasing the efficiency of biological nitrogen fixation (BNF) is essential to ensure sustainability, which can be achieved through nutritional management. Fertilization with nickel (Ni) can positively affect BNF due to the role of this micronutrient in nitrogen (N) metabolism – urease and NiFe-hy...

Selênio (Se) e enxofre (S) apresentam forte e complexa relação no metabolismo vegetal. O Selenato (SeO4 2-) e o sulfato (SO4 2-) competem por transportadores para absorção pela raiz, enquanto sinergismo também tem sido relatado, o que não é observado para o selenito (SeO3 2-). Além disso, a influência específica das formas de Se no metabolismo do S...

O selênio (Se) é um elemento análogo ao enxofre (S) e benéfico para as plantas. No entanto, o excesso de Se causa severa fitotoxidez. A glutationa (GSH) é uma molécula envolvida na proteção das células vegetais à toxidez causada por metais. Neste estudo, investigamos o papel da GSH na resistência à toxidez do selenato e na regulação da expressão de...

Selenium (Se) as a sulfur (S) analog is beneficial to plants. However, excessive Se is toxic. Glutathione (GSH) can protect plant cells from metal toxicity. In this study, we investigated the role of GSH in resistance to Se toxicity and in regulating sulfate/selenate transporter gene expression. We also examined the effects of Se and S treatments o...

Selenium uptake and its content in soybean grains are affected by Se application methods. This study evaluated the impact of Se foliar application combined with a multi-nutrient fertilizer (MNF) on soybean, establishing a Se threshold to better understand the relationship between Se content in grains and yield of two genotypes (58I60 Lança and M591...

Agronomic biofortification with selenium (Se) effectively reduces hidden hunger and increases the nutritional intake of Se in people and animals. Because sorghum is a staple diet for millions of people and is used in animal feed, it becomes a crop with biofortification potential. Consequently, this study aimed to compare organoselenium compounds wi...

Seaweed products currently emerging in Europe are known to be potentially contaminated by toxic elements. The present study focused on the contents and bioaccessibility of trace elements in seaweed products available in Belgium. A total of 231 samples were collected in markets and As, Cd, Ni, Hg, Pb, I and Se concentrations were measured. Moreover,...

Selenium (Se) as a sulfur (S) analog benefits plants. However, excessive Se is toxic. Glutathione (GSH) can protect plant cells from metal toxicity. In this study, we examined the roles of GSH in resistance to Se toxicity and in regulating transporter gene expression as well as the effects of Se and S treatments on GSH production and growth of Arab...

Quartz is one of the most common minerals in soils, mostly present in sand and silt fractions. Although quartz is basically formed of SiO2, other elements can be easily detected and assessed nowadays using a portable X-ray fluorescence (pXRF) spectrometer. Our study aims to evaluate the chemical composition of different quartz varieties, identifyin...

Following the Fundão dam failure in Brazil, 60 million m3 of iron-rich tailings were released impacting an extensive area. After this catastrophe, a detailed characterization and monitoring of iron-rich tailings is required for agronomic and environmental purposes. This can be facilitated by using proximal sensors which have been an efficient, fast...

Context USEPA 3051a is a standard analytical methodology for the extraction of inorganic substances in soils. However, these analyses are expensive, time-consuming and produce chemical residues. Conversely, proximal sensors such as portable X-ray fluorescence (pXRF) spectrometry reduce analysis time, costs and consequently offer a valuable alternat...

Since soybean is widely cultivated around the world and has a high protein content, it is a great nutritional vehicle for increasing the dietary uptake of selenium (Se). Several studies have evaluated biofortification with Se through fertilizer application in several crops. However, it is not clear how each method and source affect the total Se con...

Barium (Ba) is a non-essential element that can cause toxicity in living organisms and environmental contamination. Plants absorb barium predominantly in its divalent cationic form Ba²⁺. Sulfur (S) can decrease the availability of Ba²⁺ in the soil by causing its precipitation as barium sulfate, a compound known for its very low solubility. The obje...

Selenium (Se) is an essential micronutrient known to play an important role in the antioxidant system that can potentially influence tumor growth. We aimed to investigate the effects of dietary Se supplementation after detection of 4T1 mammary tumor growth in BALB/c mice. Thirty female mice received subcutaneous inoculation of 4T1 cells. After five...

Zinc (Zn) fertilization efficiency is often low in Oxisols due to the interaction of Zn with soil constituents and phosphorus (P). When Zn is supplied in soil fertilization as a complex via slow-release organomineral fertilizers (OMFs), it is less prone to react with soil constituents and P, thus increasing the efficiency of Zn supply to crops. How...

Zinc (Zn) and iron (Fe) are essential micronutrients for all living organisms and the major targets for crop biofortification. However, when acquired in excess quantities, Zn and Fe can be toxic to plants. In this study, we examined the interaction between Zn and Fe in soybean plants under various Zn and Fe treatments. While the level of Zn accumul...

Pristine soils under native vegetation can present high levels of potentially toxic elements when developed from the weathering of some unusual parent materials, especially ultramafic rocks and some metal ores. Here, we used various selective extractions in order to study the partition and potential availability of As in eight soils developed from...

Soybean is a major crop in Brazil and is usually grown in oxidic soils that need high rates of phosphate (P) fertilizers. Soybean is also very suitable for biofortification with Se, since its grains have high protein contents and are widely consumed worldwide (directly or indirectly). Few studies have addressed Se application under field conditions...

Soil texture is a primary variable influencing many soil chemical-physical-biological processes, providing important information for decision-making regarding sustainable soil management. The standard traditional methods for determining soil texture, however, are performed manually and are time-consuming, costly, and generate chemical wastes. As an...

Mercury (Hg) toxicity in soils depends on Hg species and other physical and chemical attributes, as selenium (Se) hotspots in soils, particularly relevant in Amazonian soils. The study of Hg species and their relations in representative locations of the Amazon rainforest biome is critical for assessing the potential risks of Hg in this environment....

The effects of selenium (Se) on plant metabolism have been reported in several studies triggering plant tolerance to abiotic stresses, yet, the effects of Se on coffee plants under chilling stress are unclear. This study aimed to evaluate the effects of foliar Se application on coffee seedlings submitted to chilling stress and subsequent plant reco...

The accumulation of cadmium (Cd) in grains and edible parts of crops poses a risk to human health. Because rice is the staple food of more than half of the world population, reducing Cd uptake by rice is critical for food safety. HydroPotash (HYP), an innovative potassium fertilizer produced with a hydrothermal process, has the characteristics of i...

Tailings from iron mining are characterized by high concentrations of iron and manganese oxides, as well as high pH values. With these characteristics, most of the potentially toxic elements (PTE) contained in the tailings are somewhat unavailable. The aim of the present study was to evaluate how a reduction in the pH of iron mine tailings may affe...

In Peru, quinoa is cultivated in agricultural systems exposed to abiotic stresses. Selenium biofortification enriches crops and enhances their defense system against water deficit. This study aimed to determine the effect of soil Se application for enhancing Se content in quinoa grains and plant tolerance under water deficit. Selenium rates were ap...

Since sorghum is the staple food for millions of people, coinciding with areas where selenium (Se) deficiency occurs, biofortification with Se in sorghum can considerably improve Se intake in humans living in these areas. In this study, the objective was to evaluate the response of sorghum plants to Se biofortification and the effect of Se foliar a...

Proximal sensing has achieved widespread popularity recently in soil science and the combination of different sensors and data processing methods is vast. Yet confusion exists about which sensor (or the combination of sensors) is worthwhile considering the budget, scope, and the goals of the project. Hence, this work aims to test many modeling comb...

The Amazon rainforest is a heterogeneous ecosystem and its soils exhibit geographically variable concentrations of trace elements. In this region, anthropic activities - e.g., agriculture and mining - are numerous and varied, and even natural areas are at risk of contamination by trace elements, either of geogenic or anthropogenic origin. A reliabl...

Selenium (Se) is a micronutrient for humans and other animals; however, it can cause severe toxicity at high concentrations. Selenium and sulfur (S) present a strict relationship in plants and soils, affecting their uptake and accumulations. Thus, addressing selenium-sulfur interaction is important to understand selenium nutrition and toxicity in p...