Appearance Of Visible Symptoms Research Articles

Turnip Yellows Virus Field Infection in Oilseed Rape: Does It Impact the Yield and Quality?

Brassica napus L., winter oilseed rape (OSR), is a major crop worldwide, with a wide range of uses and high profitability. Viruses, such as turnip yellows virus (TuYV), are becoming increasingly important, and in certain years, they can cause significant infestations in OSR. It is difficult to detect the presence of the virus during visual field inspections, as the symptoms it causes can be confused with either those caused by abiotic factors (e.g., low winter temperature, soil compaction, nutrient deficiencies, etc.) or by other viruses. The objective of this study was to determine the susceptibility of four commercial hybrids of oilseed rape to TuYV in Hungary and to determine the effect of the virus on phenotypic and yield parameters. The results showed that infection with the TuYV can be significant in OSR in some growing seasons. It was found that the appearance of visual symptoms (e.g., anthocyanin leaves) does not always confirm the presence of the virus (based on the ELISA (enzyme-linked immuno assay)), and it does not always detect a negative effect of TuYV on all phenotypic and yield parameters of the tested hybrids based on the results in one growing season.

The Potential of a Low-Cost Thermal Camera for Early Detection of Temperature Changes in Virus-Infected Chili Plants

One effect of viral infection on plant physiology is increased stomata closure so that the transpiration rate is low, which in turn causes an increase in leaf temperature. Changes in plant leaf temperature can be measured by thermography using high-resolution thermal cameras. The results can be used as an indicator of virus infection, even before the appearance of visible symptoms. However, the higher the sensor resolution of the thermal camera, the more expensive it is, which is an obstacle in developing the method more widely. This article describes the potential of thermography in detecting Tobacco mosaic virus infection in chili-pepper plants using a low-cost camera. A FLIR C2 camera was used to record images of plants in two treatment groups, non-inoculated (V0) and virus-inoculated plants (V1). Significantly, V1 had a lower temperature at 8 and 12 days after inoculation (dai) than those of V0, but their temperature was higher than V0 before symptoms were visible, i.e., at 17 dai. Thermography using low-cost thermal cameras has potency to detect early viral infection at 8 dai with accuracy levels (AUC) of 80.0% and 86.5% based on k-Nearest Neighbors and Naïve Bayes classifiers, respectively.

Noble Indices for Degree of Host Plant Resistance against Alternaria Blight in Rapeseed-mustard Genotypes

Experiments were conducted at Genetics and Plant Breeding Research Farm of N. D. University of Agriculture and Technology, Kumarganj, Faizabad (U.P.) to evaluate 15 promising genotypes of rapeseed-mustard against Alternaria blight caused by Alternaria brassicae (Berk) Sacc. and A. brassicicola (Schw) Wiltshire. It is the most destructive and major disease problem under eastern Uttar Pradesh in Indian condition causing both the quantitative and qualitative losses. The evaluation criteria for host resistance against the disease considered were the number and size of spot, number of conidia per spot on both the vegetative (leaf) and reproductive (pod) parts were regularly recorded at periodical intervals starting from the disease appearance till the physiological maturity of each genotypes. The indices which were considered for in built resistance were delayed appearance of visible symptoms, minimum number of spot and their size, number of conidia per spot as well as the minimum leaf defoliation. The disease appeared first in genotype T-9 (44 DAS) which was delayed in GSL-5 (53 DAS). The number of spot/10cm2, size, sporulation capacity in terms of conidia per spot varied invariably among the genotypes and significantly in some cases. The appearance of disease symptoms in the form of blighted spots varied invariably (44 to 53 DAS) in different genotypes. The delayed appearance of disease symptoms (53 and 52 DAS), lower number of spot / 10cm2 on leaf (3.07 and 3.65), pods (3.74 and 4.14), smallest spot size on leaf (3.54 and 3.05 cm), pods (1.22 and 1.27 cm2), number of conidia per spot on leaf (1230 and 1630), pods (130 and 150) were visualised in genotype GSL-5 and Pusa Aditya,respectively indicating a certain pattern and may be considered as attributes of disease resistance. Further, this fact was strengthened with minimum leaf defoliation (32.03 and 35.55%), PDI on leaf (12.35 and 14.16), pods (7.73 and 7.93) and ultimately the AUDPC calculated on leaf (486.70 and 551.90) and pods (282.85 and 291.05). Accordingly both the genotypes were grouped in moderately resistant (MR) category. The correlation coefficient (r) among parameters attributing to resistance behaviour worked out proved helpful in drawing the conclusion. Because very limited source of durable resistance are available, it may be suggested to exploit the two genotypes i.e.GSL-5 and Pusa Aditya for breeding programme against Alternaria blight.

Neurological manifestations in mevalonate kinase deficiency: A systematic review.

Mevalonate kinase deficiency (MKD) is a monogenic auto-inflammatory disease. Its manifestations range from partial MKD to mevalonic aciduria (MVA). All patients display a periodic fever, and MVA patients additionally exhibit severe neurological involvement. The objective of this work was to describe neurological manifestations of MKD. A systematic literature review was performed from January 1990 to January 2022. Forty-five patients from 18 case reports and five cohort studies were included in the analysis. In cohort studies, the most-reported manifestations were headaches (41%) and fatigue (31%). Serious involvements including ataxia and developmental delay were described less than 1% of patients but 22-31% of case reports. They consistently appeared in the first years of life. Retinal dystrophy was frequently reported (31%) in case reports. Other manifestations, including uveitis, aseptic meningitis, and stroke remained rare. Severe neurological manifestations are rare in MKD but are responsible for major functional disabilities. They are present at onset and never appear at follow-up of patients with mild MKD. Conversely, headaches and fatigue are frequent symptoms that should be investigated. Visual examinations should be performed on the appearance of visual symptoms. The efficacy of anti-IL-1β therapy on neurological manifestations should be further investigated.

Spectral characteristics of leaves diffuse reflection in conditions of soil drought: a study of soft spring wheat cultivars of different drought resistance

Quick and accurate nondestructive methods of water deficiency detection prior to the appearance of visible symptoms of plant deterioration as well as estimation of photosynthesis parameters are needed to effectively control conditions of plant growth, to manage crop productivity and to implement programs of "smart farming". The aim of our investigation was to analyse spectral characteristics of leaves diffuse reflection as evident in soft spring wheat cultivars (Triticum aestivum L.) of different drought resistance in optimal conditions and under the impact of soil drought; another objective was to determine the reflection indices that could serve as criteria in the phenotyping of genotypes according to their photosynthetic apparatus capacity and the efficiency of light use as well as in the forecasting of genotypes potential productivity and their drought resistance. Wheat plants of 4 drought-resistant and 4 non-resistant cultivars were grown under controlled conditions in the protected ground. In the vessels with simulated soil drought, the moisture content was 30% of total field capacity, while in the control sample it was 80%. Spectral characteristics of radiation reflected from the leaf surface were recorded with the spectrometer HR2000, and then reflection indices were calculated whose value is closely related to the activeness of the photosynthetic apparatus. The experiments conducted showed that in the system of interaction between the soil, the plant and the effective layer of the atmosphere all analysed diffuse reflection indices changed with the emergence of water deficit. The index of photosynthetic apparatus capacity (ChlRI) is less susceptible to short-term soil drought than the indices of the efficiency of light use in the process of photosynthesis (R<sub>800</sub>, photochemical reflection index (PRI<sub>mod</sub>) and flavonoid index (FRI<sub>mod</sub>)) which change significantly, so that the degree of their change may be a reliable enough indicator of plant stress caused by water deficiency. It is advisable, however, when estimating and comparing the reaction of various plant cultivars, lines and new forms to the developed water deficiency, to include in the array of plants examined those cultivars whose optical properties and the range of their variation resulting from water deficit are known. This will ensure a more reliable ranking of analysed genotypes according to their drought resistance and will enhance the accuracy of the diagnosis.

A Significantly High Abundance of "Candidatus Liberibacter asiaticus" in Citrus Fruit Pith: in planta Transcriptome and Anatomical Analyses.

Huanglongbing, a highly destructive disease of citrus, is associated with the non-culturable phloem-limited α-proteobacterium “Candidatus Liberibacter asiaticus” (CLas). The distribution patterns of CLas in infected plant are variable and not consistent, which make the CLas detection and characterization more challenging. Here, we performed a systemic analysis of CLas distribution in citrus branches and fruits of 14 cultivars. A significantly high concentration of CLas was detected in fruit pith (dorsal vascular bundle) of 14 citrus cultivars collected at fruit maturity season. A 2-year monitoring assay of CLas population in citrus branches of “Shatangju” mandarin (Citrus reticulata Blanco “Shatangju”) revealed that CLas population already exhibited a high level even before the appearance of visual symptoms in the fruit rind. Quantitative analyses of CLas in serial 1.5-cm segments of fruit piths showed the CLas was unevenly distributed within fruit pith and tended to colonize in the middle or distal (stylar end) regions of pith. The use of CLas-abundant fruit pith for dual RNA-seq generated higher-resolution CLas transcriptome data compared with the leaf samples. CLas genes involved in transport system, flagellar assembly, lipopolysaccharide biosynthesis, virulence, stress response, and cell surface structure, as well as host genes involved in biosynthesis of antimicrobial-associated secondary metabolites, was up-regulated in leaf midribs compared with fruit pith. In addition, CLas infection caused the severe collapse in phloem and callose deposition in the plasmodesmata of fruit pith. The ability of fruit pith to support multiplication of CLas to high levels makes it an ideal host tissue for morphological studies and in planta transcriptome analyses of CLas–host interactions.

Potential of VIS/NIR spectroscopy to detect and predict bitter pit in ‘Golden Smoothee’ apples

Aim of study: A portable VIS/NIR spectrometer and chemometric techniques were combined to identify bitter pit (BP) in Golden apples.Area of study: WorldwideMaterial and methods: Three different classification algorithms – linear discriminant analysis (LDA), quadratic discriminant analysis (QDA) and support-vector machine (SVM) –were used in two experiments. In experiment #1, VIS/NIR measurements were carried out at postharvest on apples previously classified according to 3 classes (class 1: non-BP; class 2: slight symptoms; class 3: severe symptoms). In experiment #2, VIS/NIR measurements were carried out on healthy apples collected before harvest to determinate the capacity of the classification algorithms for detecting BP prior to the appearance of symptoms.Main results: In the experiement #1, VIS/NIR spectroscopy showed great potential in pitted apples detection with visibly symptoms (accuracies of 75–81%). The linear classifier LDA performed better than the multivariate non-linear QDA and SVM classifiers in discriminating between healthy and bitter pitted apples. In the experiment #2, the accuracy to predict bitter pit prior to the appearance of visible symptoms decreased to 44–57%.Research highlights: The identification of apples with bitter pit through VIS/NIR spectroscopy may be due to chlorophyll degradation and/or changes in intercellular water in fruit tissue.

Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

Inherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.

Evaluating cucumber mosaic virus in capsicum germplasm using ELISA

Surveys conducted in capsicum growing localities of Solan district in Himachal Pradesh revealed a high incidence of cucumber mosaic virus. Mottling, mosaic, mid vein distortion, puckering and leaf deformation were the striking symptoms observed on the leaves of capsicum. Due to the complexities of symptoms, appearance of visual symptoms alone is not sufficient enough to establish the identity of the causal virus. Leaves from symptomatic plants were collected and serologically detected through ELISA. A total of 70 capsicum varieties/breeding lines were evaluated for their reaction to CMV, out of which 14 were found to be resistant based on their optical density values. ELISA was observed to be a quick and reliable method for indexing germplasm on a large scale.

Uso de imágenes hiperespectrales para la predicción del marchitamiento de Pinus halepensis (Mill.) en el bosque mediterráneo

<p>The increasing negative effects of climate change and the emergence of invasive species in forests around the world require the development of innovative methods to monitor and quantitatively measure the health status of woodlands. These effects are especially notable in the Mediterranean area, where the decline of stands due to recurrent droughts has increased the damage caused by secondary pests whose populations would otherwise be in balance. Remote sensing technologies allow us to work on large surfaces with reasonable precision. In particular, new spectral indices obtained from high-resolution hyperspectral and thermal images have been shown to be good predictors for the early detection of physiological changes related to diseases. In this pilot study developed in a stand of Pinus halepensis in the Comunitat Valenciana, a controlled simulation of a decay is carried out by means of sequential girdling of trees, making a subsequent field monitoring of the caused decay. Through a hyperspectral camera, the spectral information of each of these trees is analyzed in relation to their discoloration and state of observed decay. The proposed methodology allows the detection of affected trees three months before the appearance of visual symptoms, obtaining a precision higher than 0.9 with Random Forest and Support Vector Machine classifiers. The vegetation indices with better results were PRI, VGO1, VGO2, GM1 and OSAVI. This pilot study allows us to think that some of these indices can be used in the early detection of general pine wilt and, therefore, have application in the monitoring of the main threats to European forests, borer pests or quarantine organisms such as <em>Bursaphelenchus xylophilus.</em></p>

Macronutrient deficiency in snap bean considering physiological, nutritional, and growth aspects.

Nutritional deficiencies limit the growth of snap bean plants, therefore knowing the biological mechanisms involved in it is fundamental. This study is aimed to evaluate the damage caused by a deficiency of macronutrients in physiological variables that cause decreased growth and the appearance of visual symptoms in snap bean. Thus, we design a hydroponic system of snap bean cultivation in order to test the effect of macronutrient deficiencies in a controlled environment. The treatments consisted in evaluate the effects of lack of one macronutrient in time. To perform this, we used Hoagland and Arnon solution in its complete formulation (control) or without N, P; K; Mg, Ca or S in each treatment. Physiological, nutritional, and growth analyses were performed when visual deficiency symptoms of each omitted nutrient appeared. Thus, the omissions of N and P in the nutrient solution led to lower accumulations of all macronutrients in the shoot. And the K, Ca, Mg, and S omissions decreased the amounts of K, Ca, Mg, P, and S in the shoot of the snap bean plants when compared with the plants grown in the complete nutrient solution. With the lowest accumulation of macronutrients, the content of photosynthetic pigments and the photosynthetic rate were reduced, with harmful effects on plant growth. Thus, from the losses in dry matter production of the shoot, the order of limiting of macronutrients in bean plants was N < P < Ca < S < Mg < K, with a decrease of up to 86.2%, 80.1%, 51.2%, 46.5%, 25.6%, and 19.3%, respectively. The nitrogen deficiency is more evident, proven by symptoms such as chlorosis in the lower and upper third leaves and necrosis of the lower third leaves.

Photosynthetic Cost Associated With Induced Defense to Plasmopara viticola in Grapevine.

Downy mildew caused by Plasmopara viticola is one of the most destructive diseases of Vitis vinifera worldwide. Grapevine breeding programs have introgressed P. viticola-resistant traits into cultivated V. vinifera genotypes and launched interspecific hybrids with resistance against downy mildew. In general, pathogen infection affects primary metabolism, reduces plant growth and development and modifies the secondary metabolism toward defense responses, which are costly in terms of carbon production and utilization. The objective of this work was to evaluate the photosynthesis impairment by inducible defenses at the leaf level in V. vinifera cultivars resistant to P. viticola. Photosynthetic limitations imposed by P. viticola in susceptible and resistant grapevine cultivars were evaluated. Histochemical localization of hydrogen peroxide and superoxide and the activity of ascorbate peroxidase were assessed. Measurements of leaf gas exchange, chlorophyll fluorescence and the response of leaf CO2 assimilation to increasing air CO2 concentrations were taken, and photosynthetic limitations determined in cultivars Solaris (resistant) and Riesling (susceptible). The net photosynthetic rates were reduced (−25%) in inoculated Solaris plants even before the appearance of cell death-like hypersensitive reactions (“HR”). One day after “HR” visualization, the net photosynthetic rate of Solaris was reduced by 57% compared with healthy plants. A similar pattern was noticed in resistant Cabernet Blanc and Phoenix plants. While the susceptible cultivars did not show any variation in leaf gas exchange before the appearance of visual symptoms, drastic reductions in net photosynthetic rate and stomatal conductance were found in diseased plants 12 days after inoculation. Decreases in the maximum Rubisco carboxylation rate and photochemical impairment were noticed in Riesling after inoculation with P. viticola, which were not found in Solaris. Damage to the photochemical reactions of photosynthesis was likely associated with the oxidative burst found in resistant cultivars within the first 24 h after inoculation. Both chlorophyll degradation and stomatal closure were also noticed in the incompatible interaction. Taken together, our data clearly revealed that the defense response against P. viticola causes a photosynthetic cost to grapevines, which is not reversible even 12 days after the pathogen infection.

Investigating potato late blight physiological differences across potato cultivars with spectroscopy and machine learning

Understanding plant disease resistance is important in the integrated management of Phytophthora infestans, causal agent of potato late blight. Advanced field-based methods of disease detection that can identify infection before the onset of visual symptoms would improve management by greatly reducing disease potential and spread as well as improve both the financial and environmental sustainability of potato farms. In-vivo foliar spectroscopy offers the capacity to rapidly and non-destructively characterize plant physiological status, which can be used to detect the effects of necrotizing pathogens on plant condition prior to the appearance of visual symptoms. Here, we tested differences in spectral response of four potato cultivars, including two cultivars with a shared genotypic background except for a single copy of a resistance gene, to inoculation with Phytophthora infestans clonal lineage US-23 using three statistical approaches: random forest discrimination (RF), partial least squares discrimination analysis (PLS-DA), and normalized difference spectral index (NDSI). We find that cultivar, or plant genotype, has a significant impact on spectral reflectance of plants undergoing P. infestans infection. The spectral response of four potato cultivars to infection by Phytophthora infestans clonal lineage US-23 was highly variable, yet with important shared characteristics that facilitated discrimination. Early disease physiology was found to be variable across cultivars as well using non-destructively derived PLS-regression trait models. This work lays the foundation to better understand host-pathogen interactions across a variety of genotypic backgrounds, and establishes that host genotype has a significant impact on spectral reflectance, and hence on biochemical and physiological traits, of plants undergoing pathogen infection.

Phytoremediation of arsenite-contaminated environments: is Pistia stratiotes L. a useful tool?

Abstract Phytoremediation is considered an ecologically beneficial technique for removing arsenic from aquatic environments but studies on the mechanisms of tolerance to this pollutant, when present in the form of arsenite (AsIII) still need to be performed. Thus, in order to evaluate the potential of Pistia stratiotes to phytoremediation of AsIII and the morphological and biochemical responses involved in metalloid tolerance, P. stratiotes plants were exposed to four treatments: 0 (control), 5, 10 and 20 µM AsIII, remaining under treatment for 24 h for biochemical analysis and for 4 days to analyze the arsenic (As) uptake, biomass production, bioconcentration factor (BCF), translocation factor (TF) and visual symptomatology. The plants were able to accumulate As in both roots and leaves. This accumulation was higher in the treatment with 10 µM AsIII (1120.40 and 31.60 µg g−1 dry weight in roots and leaves, respectively), decreasing in the following concentration. P. stratiotes also showed a high BCF, that was higher than 1000 when exposed to 5 and 10 µM AsIII (1808.38 and 1536.02, respectively). The pollutant was maintained mainly at the root (TF was always lower than 1.0) which may be a defense mechanism of aquatic plants to As. Despite the significant accumulation of pollutant, the plants were able to maintain growth in all evaluated concentrations, although in very different proportions. In fact, while in the lower concentration of As the biomass production was not affected, in the treatment with 20 μM AsIII the dry biomass decreased in approximately 77%. The accumulation of As resulted in the appearance of visual symptoms of toxicity such as chlorosis, darkening and reduction of the root system, which were more conspicuous in the highest As concentration. The metalloid exposition also triggered biochemical alterations, increasing the membrane damage and the reactive oxygen species (ROS) levels and, once again, these damages were more intense in the plants exposed to 20 μM AsIII. The action of the antioxidant system (especially in the leaves) and the compartmentalization of the pollutant in the root system apparently was important in the P. stratiotes response to toxic compounds and allowed the plants to maintain the cell homeostasis and the growth at the two lowest As concentrations. Thus, the data suggest that P. stratiotes may has a potential for phytoremediation of aquatic environments contaminated with AsIII concentrations close to 10 µM.

Early Visual Detection of Wheat Stripe Rust Using Visible/Near-Infrared Hyperspectral Imaging.

Wheat stripe rust is one of the most important and devastating diseases in wheat production. In order to detect wheat stripe rust at an early stage, a visual detection method based on hyperspectral imaging is proposed in this paper. Hyperspectral images of wheat leaves infected by stripe rust for 15 consecutive days were collected, and their corresponding chlorophyll content (SPAD value) were measured using a handheld SPAD-502 chlorophyll meter. The spectral reflectance of the samples were then extracted from the hyperspectral images, using image segmentation based on a leaf mask. The effective wavebands were selected by the loadings of principal component analysis (PCA-loadings) and the successive projections algorithm (SPA). Next, the regression model of the SPAD values in wheat leaves was established, based on the back propagation neural network (BPNN), using the full spectra and the selected effective wavelengths as inputs, respectively. The results showed that the PCA-loadings–BPNN model had the best performance, which modeling accuracy (RC2) and validation accuracy (RP2) were 0.921 and 0.918, respectively, and the RPD was 3.363. The number of effective wavelengths extracted by this model accounted for only 3.12% of the total number of wavelengths, thus simplifying the models and improving the rate of operation greatly. Finally, the optimal models were used to estimate the SPAD of each pixel within the wheat leaf images, to generate spatial distribution maps of chlorophyll content. The visualized distribution map showed that wheat leaves infected by stripe rust could be identified six days after inoculation, and at least three days before the appearance of visible symptoms, which provides a new method for the early detection of wheat stripe rust.

Multispectral imaging for presymptomatic analysis of light leaf spot in oilseed rape

BackgroundThe use of spectral imaging within the plant phenotyping and breeding community has been increasing due its utility as a non-invasive diagnostic tool. However, there is a lack of imaging systems targeted specifically at plant science duties, resulting in low precision for canopy-scale measurements. This study trials a prototype multispectral system designed specifically for plant studies and looks at its use as an early detection system for visually asymptomatic disease phases, in this case Pyrenopeziza brassicae in Brassica napus. The analysis takes advantage of machine learning in the form of feature selection and novelty detection to facilitate the classification. An initial study into recording the morphology of the samples is also included to allow for further improvement to the system performance.ResultsThe proposed method was able to detect light leaf spot infection with 92% accuracy when imaging entire oilseed rape plants from above, 12 days after inoculation and 13 days before the appearance of visible symptoms. False colour mapping of spectral vegetation indices was used to quantify disease severity and its distribution within the plant canopy. In addition, the structure of the plant was recorded using photometric stereo, with the output influencing regions used for diagnosis. The shape of the plants was also recorded using photometric stereo, which allowed for reconstruction of the leaf angle and surface texture, although further work is needed to improve the fidelity due to uneven lighting distributions, to allow for reflectance compensation.ConclusionsThe ability of active multispectral imaging has been demonstrated along with the improvement in time taken to detect light leaf spot at a high accuracy. The importance of capturing structural information is outlined, with its effect on reflectance and thus classification illustrated. The system could be used in plant breeding to enhance the selection of resistant cultivars, with its early and quantitative capability.

Growth and Visual Symptoms of Nutrients Deficiency in Mangosteens (&amp;lt;i&amp;gt;Garcinia mangostana&amp;lt;/i&amp;gt; L.)

The aims of study were to evaluate growth and characterize the visual symptoms of macronutrient and micronutrient deficiencies in mangosteens. The seedlings were cultivated in nutritive solution containing all required macronutrient and micronutrients and in solutions with omission of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn, using the missing element technique. The experimental design was completely randomized with five replicates and twelve treatments. Symptoms of nutrient deficiency were accompanied by photographic records and described from beginning until complete definition, in which the plants were collected. Growth was evaluated through of dry mass production and nutrient contents. Nutrients omissions resulted in morphological alterations, characteristic symptoms of nutritional deficiency, promoted the reduction in dry mass production in plant, in which the Fe was most limiting, followed by N, and S. Macronutrients and micronutrients contents, without deficiencies (complete treatment) and deficient in mangosteen leaves were respectively: N (16.4 and 12.5 g kg-1); P (1.1 and 0.2 g kg-1); K (10.2 and 8.1 g kg-1); Ca (6.7 and 1.9 g kg-1); Mg (1.1 and 0.1 g kg-1); S (3.0 and 2.2 g kg-1); B (20 and 16 mg kg-1); Cu (7 and 3 mg kg-1); Fe (266 and 86 mg kg-1); Mn (58 and 17 mg kg-1). The decreasing order in appearance of visual symptoms of deficiency was N > S > K > B > Ca > P > Mg > Mn > Cu > Zn.

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 (gs) 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.

Stay-green characterization in Belgian forage maize

SUMMARYThe term ‘stay-green’ (SG) is used in studies with varieties showing delayed senescence in the field. However, delayed appearance of visual symptoms of leaf senescence does not guarantee a longer duration of photosynthesis. The question arises whether the variation in photosynthetic capacity between silage maize varieties currently on the Belgian market is large enough to define different SG types. Furthermore, physiological traits were investigated as proxies for photosynthesis, including chlorophyll concentration, nitrogen (N) concentration, SPAD readings and greenness score. Finally, the functionality of the SG trait was determined by studying dry matter (DM) and N partitioning in the plants. To address these questions, eight silage maize varieties were monitored at two sites in Belgium over 2 years (2013–2014). Two plant types were found: hereafter called ‘normal’ and ‘SG’. The SG varieties had higher values for photosynthetic capacity and they coincided with higher values for the proxies. Because a higher photosynthetic capacity did not provoke higher assimilate accumulation in the leaves, the SG trait was characterized as a cosmetic one. The SG trait influenced N dynamics in the plant: lower N translocation from the leaves to the ear resulted in lower ear N concentration and lower ear DM yield. No differences in whole-crop N concentration and whole-crop DM yield were found. As the SG trait mainly provokes shifts in partition of DM and N between vegetative and generative tissues, the energy source also shifts from starch (provided by the ear) to cell wall material (provided by the stover).

Visual Analysis for Detection and Quantification of Pseudomonas cichorii Disease Severity in Tomato Plants.

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (≥ 106 cfu/ml) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (ΦPSII) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII (Fv/Fm) was altered well after symptom development. Visible/near infrared and chlorophyll fluorescence hyperspectral images detected changes before symptom appearance at low-density inoculation. The results of this study indicate that the P. cichorii infection severity can be detected by chlorophyll fluorescence assay and hyperspectral images prior to the onset of visible symptoms, indicating the feasibility of early detection of diseases. However, to detect disease development by hyperspectral imaging, more detailed protocols and analyses are necessary. Taken together, change in chlorophyll fluorescence is a good parameter for early detection of P. cichorii infection in tomato plants. In addition, image-based visualization of infection severity before visual damage appearance will contribute to effective management of plant diseases.