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1.
J Exp Bot ; 2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38400803

RESUMO

There is a need to generate improved crop varieties adapted to the ongoing changes in the climate. We studied durum wheat canopy and central metabolism of six different photosynthetic organs in two yield-contrasting varieties. The aim was to understand the mechanisms associated with the water stress response and yield performance. Water stress strongly reduced grain yield, plant biomass and leaf photosynthesis, and downregulated C/N-metabolism genes and key protein levels, which occurred mainly in leaf blades. By contrast, higher yield was associated with high ear dry weight and lower biomass and ears per area, highlighting the advantage of reduced tillering and its consequent improvement in sink strength that promoted C/N metabolism at the whole plant level. An improved C metabolism in blades and ear bracts and N assimilation in all photosynthetic organs facilitated C/N remobilisation to the grain and promoted yield. Therefore, we propose that further yield gains in Mediterranean conditions could be achieved by considering the source-sink dynamics and the contribution of non-foliar organs, particularly N assimilation and remobilisation during the late growth stages. We highlight the power of linking phenotyping with plant metabolism to identify novel traits at the whole plant level to support breeding programmes.

2.
J Plant Physiol ; 292: 154161, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38142485

RESUMO

Contribution of inflorescences to seed filling have attracted great attention given the resilience of this photosynthetic organ to stressful conditions. However, studies have been almost exclusively focused to small grain cereals. In this study, we aimed to explore these responses in quinoa, as a climate resilient seed crop of elevated economic and nutritious potential. We compared the physiological and metabolic performance of panicles and leaves of two quinoa cultivars growing under contrasting salinity levels. Plant growth, photosynthetic and transpiratory gas exchange and chlorophyll fluorescence were monitored in inflorescences and leaves throughout the experiment. At flowering stage, young and mature leaves and panicles were sampled for key metabolic markers related to carbon, nitrogen and secondary metabolisms. When subjected to salt stress, panicles showed attenuated declines on photosynthesis, water use, pigments, amino acids, and protein levels as compared to leaves. In fact, the assimilation rates, together with a high hexose content evidenced an active photosynthetic role of the panicle under optimal and salt stress conditions. Moreover, we also found significant genotypic variability for physiological and metabolic traits of panicles and leaves, which emphasizes the study of genotype-dependent stress responses at the whole plant level. We conclude that quinoa panicles are less affected by salt stress than leaves, which encourages further research and exploitation of this organ for crop improvement and stress resilience considering the high natural diversity.


Assuntos
Chenopodium quinoa , Chenopodium quinoa/fisiologia , Carbono , Folhas de Planta/fisiologia , Estresse Salino , Fotossíntese/fisiologia , Grão Comestível
3.
J Neurooncol ; 165(1): 29-39, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37815737

RESUMO

BACKGROUND: Pachymeningeal disease (PMD) is a newly recognized pattern of brain metastasis (BrM) failure that specifically occurs following surgery with adjuvant stereotactic radiosurgery (SRS) and has unique prognostic implications relative to leptomeningeal disease (LMD). Here, we report its prevalence, prognostic implications, and associated risk factors. METHODS: A literature search was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses on PUBMED and Cochrane from January 2000 to June 2023. RESULTS: We identified 12 studies that included a total of 3992 BrM patients, 659 (16.5%) of whom developed meningeal disease (MD) following surgery plus adjuvant SRS, including either PMD or LMD. The mean prevalence of MD across studies was 20.9% (7.9-38.0%), with PMD accounting for 54.6% of this prevalence and LMD comprising the remaining 45.4%. Mean of the median overall survivals following diagnosis of PMD and LMD was 10.6 months and 3.7 months p = 0.007, respectively, a significant difference. Only 2 risk factors for PMD were reported in ≥ 2 studies and also identified as statistically significant per our meta-analysis: infratentorial location and controlled systemic disease status. CONCLUSION: While PMD has a superior prognosis to LMD, it is nevertheless a critical oncologic event associated with significant mortality and remains poorly recognized. PMD is predominantly observed in patients with controlled systemic disease status and infratentorial location. Future treatment strategies should focus on reducing surgical seeding and sterilizing surgical cavities.


Assuntos
Neoplasias Encefálicas , Neoplasias Meníngeas , Radiocirurgia , Humanos , Neoplasias Meníngeas/epidemiologia , Neoplasias Meníngeas/terapia , Neoplasias Encefálicas/cirurgia , Prognóstico , Fatores de Risco , Radiocirurgia/efeitos adversos , Estudos Retrospectivos , Resultado do Tratamento
4.
Cureus ; 15(5): e38512, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37288179

RESUMO

Solitary plasmacytoma is an uncommon hematologic malignancy characterized by the monoclonal proliferation of abnormal plasma cells in the bone or extramedullary tissues and the absence of other multiple myeloma-defining clinical characteristics. Mostly, solitary extramedullary plasmacytoma (SEP) occurs in the head and neck region, also called solitary extramedullary plasmacytoma of the head and neck (SEPHN). Although the standard of care for SEPHN is not well established, either a surgical approach or localized external beam radiotherapy (EBRT) can be used as a definitive treatment. Due to the high radiosensitivity of SEPHN, EBRT has been associated with adequate therapeutic effects in the management of SEP, with the advantage of being a noninvasive modality that yields high rates of local control with a reasonable toxicity profile. We present a case series of three patients with SEPHN treated with EBRT at our institution with clinical outcomes.

5.
Nanomaterials (Basel) ; 13(10)2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37242018

RESUMO

The inclusion of La-Mn vacancies in LaMnO3 nanoparticles leads to a noticeable change in conductivity behavior. The sample retains its overall insulator characteristic, with a typical thermal activation mechanism at high temperatures, but it presents high magnetoconductivity below 200 K. The activation energy decreases linearly with the square of the reduced magnetization and vanishes when the sample is magnetized at saturation. Therefore, it turns out that electron hopping between Mn3+ and Mn4+ largely contributes to the conductivity below the Curie temperature. The influence of the applied magnetic field on conductivity also supports the hypothesis of hopping contribution, and the electric behavior can be explained as being due to an increase in the hopping probability via spin alignment.

6.
Planta ; 257(4): 81, 2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36917306

RESUMO

MAIN CONCLUSION: The pool of carbon- and nitrogen-rich metabolites is quantitatively relevant in non-foliar photosynthetic organs during grain filling, which have a better response to water limitation than flag leaves. The response of durum wheat to contrasting water regimes has been extensively studied at leaf and agronomic level in previous studies, but the water stress effects on source-sink dynamics, particularly non-foliar photosynthetic organs, is more limited. Our study aims to investigate the response of different photosynthetic organs to water stress and to quantify the pool of carbon and nitrogen metabolites available for grain filling. Five durum wheat varieties were grown in field trials in the Spanish region of Castile and León under irrigated and rainfed conditions. Water stress led to a significant decrease in yield, biomass, and carbon and nitrogen assimilation, improved water use efficiency, and modified grain quality traits in the five varieties. The pool of carbon (glucose, glucose-6-phosphate, fructose, sucrose, starch, and malate) and nitrogen (glutamate, amino acids, proteins and chlorophylls) metabolites in leaf blades and sheaths, peduncles, awns, glumes and lemmas were also analysed. The results showed that the metabolism of the blades and peduncles was the most susceptible to water stress, while ear metabolism showed higher stability, particularly at mid-grain filling. Interestingly, the total metabolite content per organ highlighted that a large source of nutrients, which may be directly involved in grain filling, are found outside the blades, with the peduncles being quantitatively the most relevant. We conclude that yield improvements in our Mediterranean agro-ecosystem are highly linked to the success of shoots in producing ears and a higher number of grains, while grain filling is highly dependent on the capacity of non-foliar organs to fix CO2 and N. The ear organs show higher stress resilience than other organs, which deserves our attention in future breeding programmes.


Assuntos
Desidratação , Triticum , Triticum/fisiologia , Desidratação/metabolismo , Ecossistema , Melhoramento Vegetal , Carbono/metabolismo , Folhas de Planta/metabolismo , Grão Comestível/metabolismo , Nitrogênio/metabolismo
7.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1534150

RESUMO

Introduction: Foville syndrome (inferior medial pontine syndrome) is a clinical entity that makes part of a subclassification of a broader category of posterior circulation stroke. It is characterized by a blockage of the basilar artery caused by lesions in the pontine tegmentum. This syndrome has a very low incidence worldwide, but its clinical relevance is considerable. Case report: A 41-year-old patient without any medical history was admitted to the emergency department due to signs of focal neurologic deficits. Imaging findings were compatible with an ischemic lesion in the brainstem, and cerebral angiography showed involvement of the basilar artery territory. The patient was diagnosed and followed up in the intensive care unit (ICU) until his recovery. Conclusion: Foville syndrome is a rare disease with high morbidity and mortality. Early recognition and a multidisciplinary approach are decisive to improve the patient's prognosis.


Introducción. El síndrome de Foville (síndrome pontino medial inferior) es una entidad clínica que hace parte de una subclasificación de la categoría más amplia de eventos cerebrovasculares de la circulación posterior, se presenta como resultado de la oclusión de la arteria basilar debido a lesiones en el tegmento pontino. Este síndrome tiene una muy baja incidencia a nivel mundial, pero es de gran relevancia clínica. Presentación del caso. Hombre de 41 años sin antecedentes patológicos, que ingresó al servicio de urgencias por signos de focalización neurológica. Sus hallazgos imagenológicos fueron compatibles con una lesión isquémica en el tronco encefálico y la angiografía cerebral evidenció un compromiso en el territorio de la arteria basilar. El paciente fue diagnosticado y se le dio seguimiento en la unidad de cuidados intensivos (UCI) hasta su rehabilitación. Conclusión. El síndrome de Foville es una enfermedad infrecuente y de alta mortalidad. El reconocimiento temprano de esta afección y un abordaje multidisciplinario son determinantes para mejorar el pronóstico del paciente.

8.
Vaccines (Basel) ; 10(9)2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36146610

RESUMO

BACKGROUND: We conducted a longitudinal study to estimate immunity produced in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among university students over seven months. METHODS: All participants were attending a public university and resided in Pitt County, North Carolina. University students enrolled weekly for 10 weeks between 26 August 2020 and 28 October 2020, resulting in 136 young adults completing at least one study visit by 17 November 2020. Enrolled students completed an online survey and nasal swab collection at two-week intervals and monthly blood collection between 26 August 2020 and 31 March 2021. RESULTS: Amongst 695 serum samples tested during follow-up, the prevalence of a positive result for anti-nucleocapsid antibodies (N-IgG) was 9.78%. In 22 students with more than one positive N-IgG serum sample, 68.1% of the group lost persistence of N-IgG below the positive threshold over 140 days. Anti-spike IgG antibodies were significantly higher among 11 vaccinated compared to 10 unvaccinated. CONCLUSIONS: In healthy young adults, N-IgG wanes below the detectable threshold within five months. S-IgG titer remained consistently elevated months after infection, and significantly increased after vaccination.

9.
J Integr Plant Biol ; 64(2): 592-618, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34807514

RESUMO

High-throughput crop phenotyping, particularly under field conditions, is nowadays perceived as a key factor limiting crop genetic advance. Phenotyping not only facilitates conventional breeding, but it is necessary to fully exploit the capabilities of molecular breeding, and it can be exploited to predict breeding targets for the years ahead at the regional level through more advanced simulation models and decision support systems. In terms of phenotyping, it is necessary to determined which selection traits are relevant in each situation, and which phenotyping tools/methods are available to assess such traits. Remote sensing methodologies are currently the most popular approaches, even when lab-based analyses are still relevant in many circumstances. On top of that, data processing and automation, together with machine learning/deep learning are contributing to the wide range of applications for phenotyping. This review addresses spectral and red-green-blue sensing as the most popular remote sensing approaches, alongside stable isotope composition as an example of a lab-based tool, and root phenotyping, which represents one of the frontiers for field phenotyping. Further, we consider the two most promising forms of aerial platforms (unmanned aerial vehicle and satellites) and some of the emerging data-processing techniques. The review includes three Boxes that examine specific case studies.


Assuntos
Produtos Agrícolas , Melhoramento Vegetal , Produtos Agrícolas/genética , Fenótipo
10.
Urol Case Rep ; 38: 101722, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34307048

RESUMO

Individuals with Neurofibromatosis I may develop plexiform neurofibromas throughout the body, however they are rarely seen in the pelvis. We present a 15-year-old patient with NF1 with a large unresectable neurofibroma located between the prostate and bladder discovered incidentally on renal/bladder ultrasound during the evaluation of bowel/bladder dysfunction. Despite the extensive nature of the mass, the patient presented with minimal symptoms and the lesion was thought to be stool or enlarged prostate on subsequent evaluations. Urologists should be aware of NF1 related pelvic masses in the evaluation of bowel bladder dysfunction and specify NF1 on radiologic requisitions.

11.
Curr Oncol ; 28(4): 2560-2578, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-34287274

RESUMO

Lung metastases are the second most common malignant neoplasms of the lung. It is estimated that 20-54% of cancer patients have lung metastases at some point during their disease course, and at least 50% of cancer-related deaths occur at this stage. Lung metastases are widely accepted to be oligometastatic when five lesions or less occur separately in up to three organs. Stereotactic body radiation therapy (SBRT) is a noninvasive, safe, and effective treatment for metastatic lung disease in carefully selected patients. There is no current consensus on the ideal dose and fractionation for SBRT in lung metastases, and it is the subject of study in ongoing clinical trials, which examines different locations in the lung (central and peripheral). This review discusses current indications, fractionations, challenges, and technical requirements for lung SBRT.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Progressão da Doença , Fracionamento da Dose de Radiação , Humanos , Resultado do Tratamento
12.
J Am Coll Emerg Physicians Open ; 2(3): e12442, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33969355
13.
Front Plant Sci ; 11: 1289, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32973848

RESUMO

Climate change is expected to intensify water restriction to crops, impacting on the yield potential of crops such as popcorn. This work aimed to evaluate the performance of 10 field cultivated popcorn inbred lines during two growing seasons, under well-watered (WW) and water stressed (WS) (ψsoil≥ -1.5 MPa) conditions. Water stress was applied by withholding irrigation in the phenological phase of male pre-anthesis. Additionally, two contrasting inbred lines, P7 (superior line) and L75 (low performer) were compared for grain yield (GY) and expanded popcorn volume (EPV), selected from previous studies, were tested under greenhouse conditions. In the field, no genotype x water condition x crop season (G×WC×CS) interaction was observed, whereas GY (-51%), EPV (-55%) and leaf greenness (SPAD index) measured 17 days after anthesis (DAA) (> -10%) were highly affected by water limitation. In general, root traits (angles, number, and density) presented G×WC×CS interaction, which did not support their use as selection parameters. In relation to leaf senescence, for both WS and WW conditions, the superior inbred lines maintained a stay-green condition (higher SPAD index) until physiological maturity, but maximum SPAD index values were observed later in WW (48.7 by 14 DAA) than in WS (43.9 by 7 DAA). Under both water conditions, negative associations were observed between SPAD index values 15 and 8 days before anthesis DBA), and GY and EPV (r ≥ -0.69), as well as between SPAD index 7, 17, and 22 DAA, and angles of brace root (AB), number of crown roots (NC) and crown root density (CD), in WS (r ≥ -0.69), and AB and CD, in WW (r ≥ -0.70). Lower NC and CD values may allow further root deepening in WS conditions. Under WS P7 maintained higher net photosynthesis values, stomatal conductance, and transpiration, than L75. Additionally, L75 exhibited a lower (i.e., more negative) carbon isotope composition value than P7 under WS, confirming a lower stomatal aperture in L75. In summary, besides leaf greenness, traits related to leaf photosynthetic status, and stomatal conductance were shown to be good indicators of the agronomic performance of popcorn under water constraint.

14.
Sci Rep ; 10(1): 16008, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994539

RESUMO

Enhancing nitrogen fertilization efficiency for improving yield is a major challenge for smallholder farming systems. Rapid and cost-effective methodologies with the capability to assess the effects of fertilization are required to facilitate smallholder farm management. This study compares maize leaf and canopy-based approaches for assessing N fertilization performance under different tillage, residue coverage and top-dressing conditions in Zimbabwe. Among the measurements made on individual leaves, chlorophyll readings were the best indicators for both N content in leaves (R < 0.700) and grain yield (GY) (R < 0.800). Canopy indices reported even higher correlation coefficients when assessing GY, especially those based on the measurements of the vegetation density as the green area indices (R < 0.850). Canopy measurements from both ground and aerial platforms performed very similar, but indices assessed from the UAV performed best in capturing the most relevant information from the whole plot and correlations with GY and leaf N content were slightly higher. Leaf-based measurements demonstrated utility in monitoring N leaf content, though canopy measurements outperformed the leaf readings in assessing GY parameters, while providing the additional value derived from the affordability and easiness of using a pheno-pole system or the high-throughput capacities of the UAVs.


Assuntos
Nitrogênio/análise , Tecnologia de Sensoriamento Remoto/métodos , Zea mays/crescimento & desenvolvimento , Agricultura/métodos , Clorofila/análise , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Zea mays/química , Zimbábue
15.
Planta ; 252(1): 8, 2020 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-32594356

RESUMO

MAIN CONCLUSION: Coating maize seeds with the microbial plant protection product Trichoderma asperellum strain T34 is an effective form of inoculation that enhances plant performance when faced with drought stress, and it improves nutrient and kernel parameters differently in drought and non-stressed conditions. Drought is currently one of the biggest threats to maize production. Trichoderma spp. is mainly used in agriculture as plant protection product with secondary beneficial effects on plants: improved growth, nutrient uptake and plant immunity. Here, we studied the physiological performance of maize plants under two different water regimes (fully irrigated and drought conditions) and three different seed treatments: application of Trichoderma asperellum strain T34, application of a chemical fungicide (CELEST XL) or the combination of both. Regardless of water regime, T34 treatment improved kernel P and C, kernel number and dry weight. Higher populations of T34 on the rhizosphere (T34 treatment) alleviated water stress better than lower T34 populations (T34+Q treatment). Under drought, T34 treatment improved leaf relative water content, water use efficiency, PSII maximum efficiency and photosynthesis. T34-treated maize seeds maintained sufficient T34 populations to alleviate drought throughout crop development suggesting an optimal dose of 104 and 105 colony forming units g-1 dry weight of rhizosphere under the studied conditions. This work helps to demonstrate the beneficial interaction between T. asperellum strain T34 and maize plants under drought.


Assuntos
Hypocreales/fisiologia , Zea mays/microbiologia , Agricultura , Secas , Fotossíntese , Folhas de Planta/microbiologia , Folhas de Planta/fisiologia , Sementes/microbiologia , Sementes/fisiologia , Estresse Fisiológico , Água/fisiologia , Zea mays/fisiologia
16.
Int J Emerg Med ; 13(1): 25, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32410576

RESUMO

BACKGROUND: Ruptured abdominal aortic aneurysm (AAA) is a highly lethal condition which requires rapid identification and treatment to improve the chance of survival. Computed tomography is the diagnostic modality of choice for ruptured AAA though it is time-consuming and often requires movement of the patient out of the emergency department (ED). Point-of-care ultrasound in the ED has excellent sensitivity and specificity for the detection of AAA, though less is known about its use to diagnose AAA rupture. We report a case of ruptured AAA identified on ultrasound performed at the bedside in the ED. CASE PRESENTATION: A 77-year-old woman on warfarin with a known AAA presented to our ED with 2 days of epigastric abdominal pain. Point-of-care ultrasound revealed several findings suggestive of rupture of the AAA, which was confirmed on computed tomography. The patient was subsequently taken for emergent operative repair of the AAA and was later discharged from the hospital. CONCLUSIONS: Characteristics suggestive of AAA rupture may be seen on ultrasound. As ED physicians become more familiar with the use of point-of-care ultrasound in the evaluation of abdominal pain, identification of these characteristics may aid in the rapid diagnosis of AAA rupture.

17.
Cells ; 9(4)2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32326207

RESUMO

Although the relevance of spike bracts in stress acclimation and contribution to wheat yield was recently revealed, the metabolome of this organ and its response to water stress is still unknown. The metabolite profiles of flag leaves, glumes and lemmas were characterized under contrasting field water regimes in five durum wheat cultivars. Water conditions during growth were characterized through spectral vegetation indices, canopy temperature and isotope composition. Spike bracts exhibited better coordination of carbon and nitrogen metabolisms than the flag leaves in terms of photorespiration, nitrogen assimilation and respiration paths. This coordination facilitated an accumulation of organic and amino acids in spike bracts, especially under water stress. The metabolomic response to water stress also involved an accumulation of antioxidant and drought tolerance related sugars, particularly in the spikes. Furthermore, certain cell wall, respiratory and protective metabolites were associated with genotypic outperformance and yield stability. In addition, grain yield was strongly predicted by leaf and spike bracts metabolomes independently. This study supports the role of the spike as a key organ during wheat grain filling, particularly under stress conditions and provides relevant information to explore new ways to improve wheat productivity including potential biomarkers for yield prediction.


Assuntos
Metaboloma , Metabolômica , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Triticum/anatomia & histologia , Triticum/metabolismo , Biomassa , Desidratação , Secas , Genótipo , Nitrogênio/metabolismo , Análise de Componente Principal , Análise de Regressão , Triticum/genética
18.
Plant J ; 102(3): 615-630, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31808224

RESUMO

Hyperspectral techniques are currently used to retrieve information concerning plant biophysical traits, predominantly targeting pigments, water, and nitrogen-protein contents, structural elements, and the leaf area index. Even so, hyperspectral data could be more extensively exploited to overcome the breeding challenges being faced under global climate change by advancing high-throughput field phenotyping. In this study, we explore the potential of field spectroscopy to predict the metabolite profiles in flag leaves and ear bracts in durum wheat. The full-range reflectance spectra (visible (VIS)-near-infrared (NIR)-short wave infrared (SWIR)) of flag leaves, ears and canopies were recorded in a collection of contrasting genotypes grown in four environments under different water regimes. GC-MS metabolite profiles were analyzed in the flag leaves, ear bracts, glumes, and lemmas. The results from regression models exceeded 50% of the explained variation (adj-R2 in the validation sets) for at least 15 metabolites in each plant organ, whereas their errors were considerably low. The best regressions were obtained for malate (82%), glycerate and serine (63%) in leaves; myo-inositol (81%) in lemmas; glycolate (80%) in glumes; sucrose in leaves and glumes (68%); γ-aminobutyric acid (GABA) in leaves and glumes (61% and 71%, respectively); proline and glucose in lemmas (74% and 71%, respectively) and glumes (72% and 69%, respectively). The selection of wavebands in the models and the performance of the models based on canopy and VIS organ spectra and yield prediction are discussed. We feel that this technique will likely to be of interest due to its broad applicability in ecophysiology research, plant breeding programmes, and the agri-food industry.


Assuntos
Folhas de Planta/metabolismo , Triticum/metabolismo , Genótipo , Metaboloma/genética , Metaboloma/fisiologia , Fenótipo
19.
Plant Sci ; 282: 83-94, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31003614

RESUMO

Much attention has been paid to understanding the traits associated with crop performance and the associated underlying physiological mechanisms, with less effort done towards combining different plant scales, levels of observation, or including hybrids of autogamous species. We aim to identify mechanisms at canopy, leaf and transcript levels contributing to crop performance under contrasting nitrogen supplies in three barley genotypes, two hybrids and one commercial line. High nitrogen fertilization did not affect photosynthetic capacity on a leaf area basis and lowered nitrogen partial factor productivity past a certain point, but increased leaf area and biomass accumulation, parameters that were closely tracked using various different high throughput remote sensing based phenotyping techniques. These aspects, together with a larger catabolism of leaf nitrogen compounds amenable to sink translocation, contributed to higher crop production. Better crop yield and growth in hybrids compared to the line was linked to a nitrogen-saving strategy in source leaves to the detriment of larger sink size, as indicated by the lower leaf nitrogen content and downregulation of nitrogen metabolism and aquaporin genes. While these changes did not reduce photosynthesis capacity on an area basis, they were related with better nitrogen use in the hybrids compared with the line.


Assuntos
Hordeum/metabolismo , Nitrogênio/metabolismo , Aquaporinas/metabolismo , Genótipo
20.
Sensors (Basel) ; 19(8)2019 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-30995754

RESUMO

Maize is the most cultivated cereal in Africa in terms of land area and production, but low soil nitrogen availability often constrains yields. Developing new maize varieties with high and reliable yields using traditional crop breeding techniques in field conditions can be slow and costly. Remote sensing has become an important tool in the modernization of field-based high-throughput plant phenotyping (HTPP), providing faster gains towards the improvement of yield potential and adaptation to abiotic and biotic limiting conditions. We evaluated the performance of a set of remote sensing indices derived from red-green-blue (RGB) images along with field-based multispectral normalized difference vegetation index (NDVI) and leaf chlorophyll content (SPAD values) as phenotypic traits for assessing maize performance under managed low-nitrogen conditions. HTPP measurements were conducted from the ground and from an unmanned aerial vehicle (UAV). For the ground-level RGB indices, the strongest correlations to yield were observed with hue, greener green area (GGA), and a newly developed RGB HTPP index, NDLab (normalized difference Commission Internationale de I´Edairage (CIE)Lab index), while GGA and crop senescence index (CSI) correlated better with grain yield from the UAV. Regarding ground sensors, SPAD exhibited the closest correlation with grain yield, notably increasing in its correlation when measured in the vegetative stage. Additionally, we evaluated how different HTPP indices contributed to the explanation of yield in combination with agronomic data, such as anthesis silking interval (ASI), anthesis date (AD), and plant height (PH). Multivariate regression models, including RGB indices (R2 > 0.60), outperformed other models using only agronomic parameters or field sensors (R2 > 0.50), reinforcing RGB HTPP's potential to improve yield assessments. Finally, we compared the low-N results to the same panel of 64 maize genotypes grown under optimal conditions, noting that only 11% of the total genotypes appeared in the highest yield producing quartile for both trials. Furthermore, we calculated the grain yield loss index (GYLI) for each genotype, which showed a large range of variability, suggesting that low-N performance is not necessarily exclusive of high productivity in optimal conditions.

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