Showing papers by "André Rodrigues dos Reis published in 2020"

X-ray fluorescence spectroscopy (XRF) applied to plant science: challenges towards in vivo analysis of plants.

Abstract: X-ray fluorescence spectroscopy (XRF) is an analytical tool used to determine the elemental composition in a myriad of sample matrices. Due to the XRF non-destructive feature, this technique may allow time-resolved plant tissue analyses under in vivo conditions, and additionally, the combination with other non-destructive techniques. In this study, we employed handheld and benchtop XRF to evaluate the elemental distribution changes in living plant tissues exposed to X-rays, as well as real-time uptake kinetics of Zn(aq) and Mn(aq) in soybean (Glycine max (L.) Merrill) stem and leaves, for 48 hours, combined with transpiration rate assessment on leaves by an infrared gas analyzer (IRGA). We found higher Zn content than Mn in stems. The latter micronutrient, in turn, presented higher concentration in leaf veins. Besides, both micronutrients were more concentrated in the first trifolium (i.e., youngest leaf) of soybean plants. Moreover, the transpiration rate was more influenced by circadian cycles than Zn and Mn uptake. Thus, XRF represents a convenient tool for in vivo nutritional studies in plants, and it can be coupled successfully to other analytical techniques.

Mechanisms of cadmium-stress avoidance by selenium in tomato plants.

Abstract: Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H2O2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H2O2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants.

Agronomic biofortification with selenium impacts storage proteins in grains of upland rice.

Abstract: Background Selenium (Se) is an essential element for humans and animals. Rice is one of the most commonly consumed cereals in the world, so the agronomic biofortification of cereals with Se may be a good strategy to increase the levels of daily intake of Se by the population. This study evaluated the agronomic biofortification of rice genotypes with Se and its effects on grain nutritional quality. Five rates of Se (0, 10, 25, 50, and 100 g ha -1 ) were applied as selenate via the soil to three rice genotypes under field conditions. Results Selenium concentrations in the leaves and polished grains increased linearly in response to Se application rates. A highly significant correlation was observed between the Se rates and the Se concentration in the leaves and grains, indicating high translocation of Se. The application of Se also increased the concentration of albumin, globulin, prolamin, and glutelin in polished grains. Conclusion Biofortifying rice genotypes using 25 g Se ha -1 could increase the average daily Se intake from 4.64 to 66 μg day-1 . Considering that the recommended daily intake of Se by adults is 55 μg day-1 , this agronomic strategy could contribute to alleviating widespread Se malnutrition. © 2019 Society of Chemical Industry.

Soybean seed vigor discrimination by using infrared spectroscopy and machine learning algorithms.

Abstract: A novel approach to distinguish soybean seed vigor based on Fourier transform infrared spectroscopy (FTIR) associated with chemometric methods is presented. Batches with high and low vigor soybean seeds were analyzed. Support vector machine (SVM), K-nearest neighbors (KNN), and discriminant analysis were applied to the raw spectral and reduced-dimensionality data from PCA (principal component analysis). Proteins, fatty acids, and amides were identified as the main molecules responsible for the discrimination of the batches. The cross-validation tests pointed out that high vigor soybean seeds were successfully discriminated from low vigor ones with an accuracy of 100%. These findings indicate FTIR spectroscopy associated with multivariate analysis as a new alternative approach to discriminate seed vigor.

Spatial distribution of structural elements in leaves of Ilex paraguariensis: physiological and ecological implications

Abstract: Calcium accumulation in crystals (mainly in the midrib) and silicon on the external surface of the upper epidermis suggests physiological and/or ecological roles. Concentration, form, and location of elements in leaf tissue of Ilex paraguariensis A. St.-Hil. can influence remobilization patterns and release of substances during its infusion for making yerba mate beverages. Even though, spatial distribution of elements and characterization of crystal formation in I. paraguariensis has not been elucidated. For filling this gap, this study used microanalytical techniques to evaluate accumulation and spatial distribution of elements in yerba mate leaves, which was done using chemical analyses and scanning electron microscopy combined with energy-dispersive spectroscopy (SEM–EDS). Chemical analyses confirmed high concentrations of potassium (K) and manganese (Mn) in leaves. Cell walls were predominantly composed of carbon (C) and oxygen (O). Compartmentalization of silicon (Si) occurred on the external surface of the upper epidermis between cell walls and the leaf cuticle. Precipitation of calcium (Ca) was higher in the midrib than in the leaf blade with the mesophyll and palisade mesophyll being the main accumulation sites. Microscopy–spectroscopy analysis revealed different patterns of elemental accumulation in leaves, which suggests physiological and/or ecological roles in yerba mate plants. Additionally, the abundance of Ca oxalates could explain the low Ca solubility during the beverage infusion process.

Bradyrhizobium sp. enhance ureide metabolism increasing peanuts yield

Abstract: This study aimed to evaluate the effects of seed inoculation with Bradyrhizobium sp. and co-inoculation with Azospirillum brasilense. The seed treatments were as follows: control (without inoculation); A. brasilense (2 mL per kg−1 of seed); A. brasilense (4 mL per kg−1 of seed); Bradyrhizobium sp. (2 mL per kg−1 of seed); Bradyrhizobium sp. (4 mL per kg−1 of seed); A. brasilense + Bradyrhizobium sp. (2 mL of each strain per kg−1 of seed); and A. brasilense + Bradyrhizobium sp. (4 mL of each strain per kg−1 of seed). Peanut plants from seeds inoculated with Bradyrhizobium sp. and A. brasilense exhibited highest leaf concentration of photosynthetic pigments, carotenoids, nitrate, ammonia and amino acids. The inoculation of seeds with Bradyrhizobium sp. resulted in plants with increased concentrations of total soluble sugars, and ureides compared to the untreated plants. In contrast, seeds treated with A. brasilense alone resulted in plants exhibiting highest concentration of amino acids, which represent the highest concentration of nitrogen compounds in peanut plants. Seed inoculation with Bradyrhizobium sp. at a rate of 2 mL kg−1 was identified as the best treatment to promote increased biological nitrogen fixation and generate higher peanut yields.

Cobalt and molybdenum stimulate compounds of primary metabolism, nitrogen forms, and photosynthetic pigments in peanut plants (Arachis hypogaea L.)

Abstract: The objective of this study was to evaluate the effects of cobalt (Co) and molybdenum (Mo) doses in the treatment of seeds on the biosynthesis of nitrogen compounds, photosynthetic pigments, sugars...

Nutrition, yield and nutrient export in common bean under zinc fertilization in no-till system

Abstract: Zinc (Zn) is one of the most deficient plant micronutrients in agricultural crops. The objective of this study was to evaluate plant nutrition, grain yield and nutrient export rate in response to soil and foliar Zn fertilization in common bean (Phaseolus vulgaris L.). Two field experiments in no-till system were carried out using two common bean cultivars, BRS Esteio (black bean) and IPR Campos Gerais (Carioca bean). Treatments were composed of soil Zn application during sowing and foliar Zn spray at flowering stage. Soil Zn application had effect on leaf Zn concentration in IPR Campos Gerais and did not affect grain yield of both cultivars. Foliar Zn spray increased leaf Zn concentration by approximately two times in both cultivars, but negatively affected the grain yield in BRS Esteio. Leaf concentration of N, Ca and S were affected by soil Zn application and leaf concentration of Mn was affected by foliar Zn spray, while leaf concentration of P, K, Mg, Cu and Fe were not influenced by the soil and foliar Zn treatments. In treatments without Zn, the descending order of nutrient export rate from the experimental site was as follows: N > K > P > Ca ≈ S > Mg for macronutrients and Fe > Mn > Cu > Zn for micronutrients. Foliar Zn spray increased the export rate of Zn, P, Ca, Mg, S, Mn, Cu and Fe in IPR Campos Gerais, while soil Zn application resulted in higher export rate of P, K and Mn in BRS Esteio.

Changes in photosynthesis and antioxidant metabolism of cotton (Gossypium hirsutum L.) plants in response to manganese stress

Abstract: This study aimed to assess the physiological and biochemical responses of cotton plants to manganese (Mn2+) nutrition. Four cotton genotypes (G1 – TMG 47; G2 – FM 975 WS; G3 – TMG 11 WS and G4 – IM...

Nitrogen doses and nutritional diagnosis of virus-free garlic

Abstract: The recommendations of nitrogen (N) fertilization in garlic are still based on different varieties of the current types that are infected with phytopathogenic virus. There are several methods for recommendation of nitrogen (N) fertilization in garlic, but there are no enough methods for N diagnosis in garlic obtained by meristem culture. The objective of this work was to evaluate methods for diagnosing the nutritional status of virus-free garlic subjected to N doses through the use of a specific NO3– [...]

Agronomic biofortification of beet plants with zinc via seed priming1

Abstract: One-fifth of the world's population consumes too little zinc (Zn) causing deficiencies that can damage cells, stunt growth, and decrease immune response. This study evaluated the effect of time on the priming of beet seeds, in solutions enriched with Zn, on physiology, growth, production, and root biofortification. Two greenhouse experiments were conducted during spring 2015 and autumn 2016. In each experiment, 24 treatments were tested which comprised various combinations of three Zn concentrations (0, 10, and 30 mg mL-1), two Zn sources (sulphate and chloride), and four time periods (12, 16, 20, and 24 h), arranged in a randomised block design with four replicates. The concentration of Zn, mainly as sulphate, affected all parameters evaluated in the beet plants, such as fresh and dry root mass, photosynthesis, and root Zn concentration (biofortification). Compared to the control, fresh root mass increased 70 and 100 g per plant with 10 mg mL-1 of Zn during the experiments in 2015 and 2016, respectively. The same concentration for 16 h produced the highest Zn concentration in the roots, achieving 121 and 42 mg kg-1 in 2015 and 2016, respectively. Priming seeds in solutions enriched with Zn, thus, benefited the physiological response of the beet plants by promoting increases in growth, production, and biofortification of beet roots. Therefore, this method can be used to biofortify beet plants agronomically, regardless of the Zn source.

Effect of Sulfur Sources on Megathyrsus Maximus ‘Mombaça’ Grass Cultivated in a Typic Ultisol

Abstract: The deficiency of sulfur (S) in agricultural soils has been aggravated in recent decades, mainly by the application of high concentration fertilizers that are S-free and intensive agricultural acti...