Efficiency of essential oils in the control of the black bean aphid Aphis craccivora Koch (Hemiptera: Aphididae)

The black aphid Aphis craccivora Koch is one of the main pests of the caupi-bean crop Vigna unguiculata (L.) Walp. Due to the need to find effective and safe methods of control, there has been an increase in research seeking natural alternatives. Thus, the objective of this work was to evaluate the potential of essential oils from jatoba Hymenaea courbaril, copaiba Copaifera langsdorffii and aroeira Schinus terebinthifolius to control nymphs and adults of A. craccivora. The oils were extracted from the leaves by the hydrodistillation method, diluted to 0.1% in distilled water with 2% dimethyl sulfoxide (DMSO). Each treatment had four repetitions, plus a control with distilled water + 2% DMSO. The biotests were conducted in two stages: the first was conducted in the laboratory, under controlled conditions of temperature, relative humidity and photophase, and the second was conducted in the greenhouse, using only the treatment with the best laboratory test results. After 24, 48, 72, 96 and 120 hours of exposure, the insect mortalities were checked. In the first phase of the experiment, the aroeira oil showed 83.33% and 75.75% efficiency of mortality in nymphs and adults, respectively. In the greenhouse tests, this same oil showed 73.52% in nymphs and 62.85% in adults, opening new perspectives regarding its use as a natural insecticide for the control of the black aphid of the bean.

Leaf 13C and 15N composition shedding light on easing drought stress through partial K substitution by Na in eucalyptus species

This work aimed to investigate the partial K-replacement by Na supply to alleviate drought-induced stress in Eucalyptus species. Plant growth, leaf gas exchange parameters, water relations, oxidative stress (H₂O₂ and MDA content), chlorophyll concentration, carbon (C) and nitrogen (N) isotopic leaf composition (δ¹³C and δ¹⁵N) were analyzed. Drought tolerant E. urophylla and E. camaldulensis showed positive responses to the partial K substitution by Na, with similar dry mass yields, stomatal density and total stomatal pore area relative to the well K-supplied plants under both water conditions, suggesting that 50% of the K requirements is pressing for physiological functions that is poorly substituted by Na. Furthermore, E. urophylla and E. camaldulensis up-regulated leaf gas exchanges, leading to enhanced long-term water use efficiency (WUE_L). Moreover, the partial K substitution by Na had no effects on plants H₂O₂, MDA, δ¹³C and δ¹⁵N, confirming that Na, to a certain extent, can effectively replace K in plants metabolism. Otherwise, the drought-sensitive E. saligna species was negatively affected by partial K replacement by Na, decreasing plants dry mass, even with up-regulated leaf gas exchange parameters. The exclusive Na-supplied plants showed K-deficient symptoms and lower growth, WUE_L, and δ¹³C, besides higher Na accumulation, δ¹⁵N, H₂O₂ and MDA content.

Unravelling homeostasis effects of phosphorus and zinc nutrition by leaf photochemistry and metabolic adjustment in cotton plants

Phosphorus (P) and zinc (Zn) uptake and its physiological use in plants are interconnected and are tightly controlled. However, there is still conflicting information about the interactions of these two nutrients, thus a better understanding of nutritional homeostasis is needed. The objective of this work was to evaluate responses of photosynthesis parameters, P-Zn nutritional homeostasis and antioxidant metabolism to variation in the P × Zn supply of cotton (Gossypium hirsutum L.). Plants were grown in pots and watered with nutrient solution containing combinations of P and Zn supply. An excess of either P or Zn limited plant growth, reduced photosynthesis-related parameters, and antioxidant scavenging enzymes. Phosphorus uptake favoured photochemical dissipation of energy decreasing oxidative stress, notably on Zn-well-nourished plants. On the other hand, excessive P uptake reduces Zn-shoot concentration and decreasing carbonic anhydrase activity. Adequate Zn supply facilitated adaptation responses to P deficiency, upregulating acid phosphatase activity, whereas Zn and P excess were alleviated by increasing P and Zn supply, respectively. Collectively, the results showed that inter ionic effects of P and Zn uptake affected light use and CO2 assimilation rate on photosynthesis, activation of antioxidant metabolism, acid phosphatase and carbonic anhydrase activities, and plant growth-related responses to different extents.

Enhancing potassium content in leaves and stems improves drought tolerance of eucalyptus clones

Eucalyptus are widely planted in regions with low rainfall, occasioning frequent drought stresses. To alleviate the stress-induced effects on plants growing in these environments, soil fertilization with potassium (K) may affect drought-adaptive plant mechanisms, notably on tropical soils with low K availability. This work aimed to evaluate the K dynamic nutrition in eucalyptus in response to soil-K and -water availabilities, correlating the K-nutritional status with the physiological responses of contrasting eucalyptus clones to drought tolerance. A complete randomized design was used to investigate the effects of three water regimes (well-watered, moderate water deficit, and severe water deficit) and two K soil supplies (sufficient and low K) on growth and physiological responses of two elite eucalyptus clones: "VM01" (Eucalyptus urophylla × camaldulensis) and "AEC 0144" (E. urophylla). Results depicted that the K-well-nourished E. urophylla × camaldulensis clone under severe water deficit maintained shoot biomass accumulation by upregulating the K-content in leaves and stems, gas exchange, water-use efficiency (WUE_I ), leaf water potential (Ψw), and chlorophyll a fluorescence parameters, compared to E. urophylla clone. Meanwhile, E. urophylla with a severe water deficit showed a decreased of K content in leaves and stem, as well as a reduction in the accumulation of dry mass. Therefore, the K-use efficiency and the apparent electron transport rate through photosystem II were positively correlated in plants grown in low K, indicating the importance of K in maintaining leaf photochemical processes. In conclusion, management strategy should seek to enhance K-nutrition to optimize water-use efficiencies and photosynthesis.

Corrigendum: Partial Substitution of K by Na Alleviates Drought Stress and Increases Water Use Efficiency in Eucalyptus Species Seedlings

[This corrects the article DOI: 10.3389/fpls.2021.632342.].

Selenium biofortification enhances ROS scavenge system increasing yield of coffee plants

There are conclusive evidences of selenium (Se) deficiency in Brazilian soils and foods. Brazil is the largest producer and consumer of coffee worldwide, which favors agronomic biofortification of its coffee. This study aimed to evaluate effects of foliar application of three formulations and six rates of Se on antioxidant metabolism, agronomic biofortification and yield of coffee beans. Seven Se concentrations (0, 10, 20, 40, 80, 100 and 160 mg L^-1) were applied from three formulations of Se (sodium selenate, nano-Se 1500, and nano-Se 5000). Selenium application up to 40 mg L^-1 increased the concentration of photosynthetic pigments such as chlorophylls, pheophytins and carotenoids in coffee leaves. Foliar application of Se ranging from 20 to 80 mg L^-1 decreased lipid peroxidation and concentration of hydrogen peroxide, but increased superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase activities in coffee leaves. These results indicated that foliar Se application stimulates antioxidative metabolism to mitigate reactive oxygen species. Foliar application of 20 mg Se L^-1 of sodium selenate increased coffee yield by 38%, and 160 mg Se L^-1 of nano-Se 5000 increased dramatically coffee yield by 42%. Selenium concentration in grains ranged from 0.116 to 4.47 mg kg^-1 (sodium selenate), 4.84 mg kg^-1 (nano-Se 1500) and 5.82 mg kg^-1 (nano-Se 5000). The results suggest the beneficial effect of Se on the increment of photosynthetic pigments, antioxidative metabolism, increased coffee yield and nutritional quality of grains. The recommended foliar Se application in this study can mitigate abiotic stressors such as high temperatures resulting in higher yield of coffee plants.

Partial Substitution of K by Na Alleviates Drought Stress and Increases Water Use Efficiency in Eucalyptus Species Seedlings

Eucalyptus, the most widely planted tree genus worldwide, is frequently cultivated in soils with low water and nutrient availability. Sodium (Na) can substitute some physiological functions of potassium (K), directly influencing plants' water status. However, the extent to which K can be replaced by Na in drought conditions remains poorly understood. A greenhouse experiment was conducted with three Eucalyptus genotypes under two water conditions (well-watered and water-stressed) and five combination rates of K and Na, representing substitutions of 0/100, 25/75, 50/50, 75/25, and 100/0 (percentage of Na/percentage of K), to investigate growth and photosynthesis-related parameters. This study focused on the positive effects of Na supply since, depending on the levels applied, the Na supply may induce plants to salinity stress (>100 mM of NaCl). Plants supplied with low to intermediate K replacement by Na reduced the critical level of K without showing symptoms of K deficiency and provided higher total dry matter (TDM) than those Eucalyptus seedlings supplied only with K in both water conditions. Those plants supplied with low to intermediate K replacement by Na had improved CO₂ assimilation (A), stomatal density (Std), K use efficiency (UE _K ), and water use efficiency (WUE), in addition to reduced leaf water potential (Ψw) and maintenance of leaf turgidity, with the stomata partially closed, indicated by the higher values of leaf carbon isotope composition (δ¹³C‰). Meanwhile, combination rates higher than 50% of K replacement by Na led to K-deficient plants, characterized by the lower values of TDM, δ¹³C‰, WUE, and leaf K concentration and higher leaf Na concentration. There was positive evidence of partial replacement of K by Na in Eucalyptus seedlings; meanwhile, the ideal percentage of substitution increased according to the drought tolerance of the species (Eucalyptus saligna < Eucalyptus urophylla < Eucalyptus camaldulensis).

Coffea arabica seedlings genotypes are tolerant to high induced selenium stress: Evidence from physiological plant responses and antioxidative performance

Selenium (Se) is considered a beneficial element to higher plants based on its regulation of antioxidative system under abiotic or biotic stresses. However, the limit of beneficial and toxic physiological effects of Se is very narrow. In the present study, the antioxidant performance, nutritional composition, long-distance transport of Se, photosynthetic pigments, and growth of Coffea arabica genotypes in response to Se concentration in solution were evaluated. Five Coffea arabica genotypes (Obatã, IPR99, IAC125, IPR100 and Catucaí) were used, which were grown in the absence and presence of Se (0 and 1.0 mmol L^-1) in nutrient solution. The application of 1 mmol L^-1 Se promoted root browning in all genotypes. There were no visual symptoms of leaf toxicity, but there was a reduction in the concentration of phosphorus and sulfur in the shoots of plants exposed to high Se concentration. Except for genotype Obatã, the coffee seedlings presented strategies for regulating Se uptake by reducing long-distance transport of Se from roots to shoots. The concentrations of total chlorophyll, total pheophytin, and carotenoids were negatively affected in genotypes Obatã, IPR99, and IAC125 upon exposure to Se at 1 mmol L^-1. H₂O₂ production was reduced in genotypes IPR99, IPR100, and IAC125 upon exposure to Se, resulting in lower activity of superoxide dismutase (SOD), and catalase (CAT). These results suggest that antioxidant metabolism was effective in regulating oxidative stress in plants treated with Se. The increase in sucrose, and decrease in SOD, CAT and ascorbate peroxidase (APX) activities, as well as Se compartmentalization in the roots, were the main biochemical and physiological modulatory effects of coffee seedlings under stress conditions due to excess of Se.

Mechanisms of cadmium-stress avoidance by selenium in tomato plants

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

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.

Phosphorus-zinc interactions in cotton: consequences for biomass production and nutrient-use efficiency in photosynthesis

The fragmentary information on phosphorus (P) × zinc (Zn) interactions in plants warrants further study, particularly in plants known for their high P and Zn requirements, such as cotton (Gossypium hirsutum L.). The objective of this study was to investigate the effect of P × Zn interactions in a modern cultivar of cotton grown hydroponically. Biomass, mineral nutrition and photosynthetic parameters were monitored in plants receiving contrasting combinations of P and Zn supply. Root biomass, length and surface area were similar in plants with low P and/or low Zn supply to those in plants grown with high P and high Zn supply, reflecting an increased root/shoot biomass quotient when plants lack sufficient P or Zn for growth. Increasing P supply and reducing Zn supply increased shoot P concentrations, whilst shoot Zn concentrations were influenced largely by Zn supply. A balanced P × Zn supply (4 mM P × 4 μM Zn) enabled greatest biomass accumulation, while an imbalanced supply of these nutrients led to Zn deficiency, P toxicity or Zn toxicity. Net photosynthetic rate, stomatal conductance, transpiration rate and instantaneous carboxylation efficiency increased as P or Zn supply increased. Although increasing P supply reduced the P-use efficiency in photosynthesis (PUEP) and increasing Zn supply reduced the Zn-use efficiency in photosynthesis (ZnUEP), increasing Zn supply at a given P supply increased PUEP and increasing P supply at a given Zn supply increased ZnUEP. These results suggest that agricultural management strategies should seek for balanced mineral nutrition to optimize yields and resource-use efficiencies.

Depicting the physiological and ultrastructural responses of soybean plants to Al stress conditions

Aluminium (Al) is a toxic element for plants living in soils with acidic pH values, and it causes reductions in the roots and shoots development. High Al concentrations can cause physiological and structural changes, leading to symptoms of toxicity in plant tissue. The aim of this study was to describe the Al toxicity in soybean plants through physiological, nutritional, and ultrastructure analyses. Plants were grown in nutrient solution containing increasing Al concentrations (0; 0.05; 0.1; 1.0, 2.0 and 4.0 mmol L-1). The Al toxicity in the soybean plants was characterized by nutritional, anatomical, physiological, and biochemical analyses. The carbon dioxide assimilation rates and stomatal conductance were not affected by the Al. However, the capacity for internal carbon use decreased, and the transpiration rate increased, resulting in increased root biomass at the lowest Al concentration in the nutrient solution. The soybean plants exposed to the highest Al concentration exhibited lower root and shoot biomass. The nitrate reductase and urease activities decreased with the increasing Al concentration, indicating that nitrogen metabolism was halted. The superoxide dismutase and peroxidase activities increased with the increasing Al availability in the nutrient solution, and they were higher in the roots, showing their role in Al detoxification. Despite presenting external lesions characterized by a damaged root cap, the root xylem and phloem diameters were not affected by the Al. However, the leaf xylem diameter showed ultrastructural alterations under higher Al concentrations in nutrient solution. These results have contributed to our understanding of several physiological, biochemical and histological mechanisms of Al toxicity in soybean plants.

Prognosis of physiological disorders in physic nut to N, P, and K deficiency during initial growth

The description of physiological disorders in physic nut plants deficient in nitrogen (N), phosphorus (P) and potassium (K) may help to predict nutritional imbalances before the appearance of visual symptoms and to guide strategies for early nutrient supply. The aim of this study was to evaluate the growth of physic nuts (Jatropha curcas L.) during initial development by analyzing the gas exchange parameters, nutrient uptake and use efficiency, as well as the nitrate reductase and acid phosphatase activities and polyamine content. Plants were grown in a complete nutrient solution and solutions from which N, P or K was omitted. The nitrate reductase activity, phosphatase acid activity, polyamine content and gas exchange parameters from leaves of N, P and K-deficient plants indicates earlier imbalances before the appearance of visual symptoms. Nutrient deficiencies resulted in reduced plant growth, although P- and K-deficient plants retained normal net photosynthesis (A), stomatal conductance (g_s) and instantaneous carboxylation efficiency (k) during the first evaluation periods, as modulated by the P and K use efficiencies. Increased phosphatase acid activity in P-deficient plants may also contribute to the P use efficiency and to A and gs during the first evaluations. Early physiological and biochemical evaluations of N-, P- and K-starved plants may rely on reliable, useful methods to predict early nutritional imbalances.

Physiological highlights of manganese toxicity symptoms in soybean plants: Mn toxicity responses

Manganese (Mn) is an essential element for plants; however, high concentrations in certain soil conditions can cause toxicity symptoms in the plant tissue. Here, we describe Mn toxicity symptoms and Mn toxicity responses in soybean plants. Soybean plants exposed to excess Mn showed reductions in the CO2 assimilation rate and stomatal conductance, which in turn resulted in decreased shoot biomass. Furthermore, peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activity were higher in plants grown with the highest Mn concentration. The Mn doses increased the activity of antioxidant enzymes such as CAT, POD, and SOD. The toxicity symptoms presented by the leaves included hypertrophying of the adaxial epidermis and the formation of necrotic areas with purple-colored veins. Dramatic movement of calcium from the healthy region to the purple-colored necrotic region was observed, as was the exit of potassium from the necrotic area to the healthy region of the tissue. The high activities of POD and SOD in the presence of high Mn compartmented in the roots was the main physiological responses at high Mn uptake by soybean plants.

DMAICR in an ergonomic risks analysis

The DMAICR problem-solving methodology is used throughout this paper to show you how to implement ergonomics recommendations. The DMAICR method consists of the following five six steps by which you can solve ergonomic design problems: The steps of the proposed method, adapting DMAICR, are the following: In the steep D, there is the definition of the project or the situation to be assessed and its guiding objectives, known as demand. In the step M, it relates to the work, tasks and organizational protocols and also includes the need of measuring. In the step A, all concepts are about the analysis itself. The step I is the moment of improving or incrementing. In the step C, control, prevention from prospective troublesome situation and implementation of management are the activities controlling the situation. R is Report. Some relevant technical and conceptual aspects for the comparison of these methodologies are illustrated in this paper. The steps of DMAICR were taken by a multifunctional team (multi-professional and multi-disciplinary) termed as focus group, composed by selected members of the company and supported by experts in ergonomics.

The relationship between the profile of severity of addiction and the retention of patients in the ambulatory program of DDTP

OBJECTIVES

The authors described some variables related to the retention of drug dependent veterans receiving outpatient treatment at San Juan V.A.M.C. and compared the profile of addiction severity with retention using a global dysfunction scale.

METHODS

The clinical charts of 74 patients were examined at random using a 16-item questionnaire based on the ASI scale. The data was processed and analyzed using the Epi Info V6.2 computer program, utilizing chi square as the main statistics.

RESULTS

The patient's retention in treatment for > or = to 3 months was associated with some specific variables such as: more than 12 years of education, being Catholic, divorced, living with parents, use of more than one drug of preference, having a negative urine toxicology result before treatment and after treatment, and showing a favorable change in urine toxicology results. In terms of severity of dysfunction, a considerable substance problem and an extreme legal problem were associated with a retention of > or = to 3 months, as well as no evidence of occupational problems.

CONCLUSION

The strong correlation between specific variables and the retention of patients in treatment for > or = to 3 months should create awareness of the importance of available and effective treatments in the fight against substance abuse and mental health problems as well as to educate and integrate family members in patients treatment, since a supportive family member is one of the best tools that patients and therapist can have to help maintain patient's sobriety.

A descriptive-exploratory study of outcome and some biopsychosocial characteristics of drug dependent veterans in Puerto Rico

OBJECTIVE

The authors attempted to correlate outcomes with various significant biopsychosocial variables in drug dependent veterans receiving outpatient treatment at San Juan V.A.M.C.

METHODS

The clinical charts of 120 inactive patients were examined using a 50 item questionnaire. The data was processed and analyzed using the EpiInfo v.5 computer program. The outcome of the patients was measured using a Goal Attainment Scale Technique with demonstrated validity and reliability.

RESULTS

The patients retention in treatment for 12 or more visits and its relationship to good outcomes was the most significant finding of this study (P < 0.00000000, 80.5% of patients improved). Only 5% of patients with 3 or less visits showed positive outcomes. Another variable associated with good outcomes was a supportive wife (P < 0.02). HIV reactivity was strongly correlated with IV drug use (P < 0.037).

CONCLUSIONS

The strong correlation of the retention of patients in treatment for 12 or more visits and good outcomes should alert clinicians and policy makers as to the importance of available and effective treatments in the fight against substance abuse and mental health problems. This study also showed that a supportive family member is usually the best social asset that patients and therapists have in their fight for sobriety.

A naturalistic analytic study of veterans using naltrexone in Puerto Rico

Clinical records of eighteen patients on Naltrexone and 13 patients who dropped out of a Naltrexone maintenance activity were studied at random to delineate the biopsychosocial characteristics of greater clinical relevance to an outpatient rehabilitation program. Their similarities and differences were described. Some hypothesis that may prove to be great clinical benefit were presented. A striking finding was the greater capacity of the Naltrexone group to have a stable marital relationship (P less than 0.01) as compared with the group who abandoned treatment.