Vegetative Cycle Research Articles

Heavy Metals Behavior in the Presence of Organic Acids and Proteins in the Rhizosphere and Plant Tissues of Yellow Melon var. Natal (Cucumis melo L.) Cultivated in a Quartzarenic Neosol

We propose to identify the influence of organic acids as well as total proteins in the accumulation and translocation of heavy metals from the rhizosphere to the plant organs of cultivated yellow melon var. Natal throughout the vegetative cycle. Physical and chemical attributes and the concentration of Cu, Zn, and Pb were determined in soil samples. Samples of plant tissue and rhizosphere at 0, 15, 30, 45, and 60 days after transplantation were collected and determined the concentration of heavy metals along with the content of total protein in the tissues and organic acids in the rhizosphere. Subsequently, the transfer factor (TF) and bioconcentration factor (BF) were calculated. Oxalic and citric acids and heavy metal contents were slightly higher in the rhizosphere than those found in the soil. The organic acids and total protein showed correlations with the concentration of heavy metals in different organs of the plant. The protein content in the plant tissues and the contents of oxalic and citric acid released by the plant in the rhizosphere can increase or decrease the absorption, accumulation, and translocation of Cu, Zn, and Pb in the different organs of the yellow melon var. Natal. Even the BF and TF showed values higher than one, being indicative of phytoextraction potential in several stages of the vegetative cycle for Cu and Zn, the yellow melon var. Natal cannot be considered as a hyperaccumulator plant for not meeting all necessary criteria for that purpose.

Wild Isolates of Neurospora crassa Reveal Three Conidiophore Architectural Phenotypes.

The vegetative life cycle in the model filamentous fungus, Neurospora crassa, relies on the development of conidiophores to produce new spores. Environmental, temporal, and genetic components of conidiophore development have been well characterized; however, little is known about their morphological variation. We explored conidiophore architectural variation in a natural population using a wild population collection of 21 strains from Louisiana, United States of America (USA). Our work reveals three novel architectural phenotypes, Wild Type, Bulky, and Wrap, and shows their maintenance throughout the duration of conidiophore development. Furthermore, we present a novel image-classifier using a convolutional neural network specifically developed to assign conidiophore architectural phenotypes in a high-throughput manner. To estimate an inheritance model for this discrete complex trait, crosses between strains of each phenotype were conducted, and conidiophores of subsequent progeny were characterized using the trained classifier. Our model suggests that conidiophore architecture is controlled by at least two genes and has a heritability of 0.23. Additionally, we quantified the number of conidia produced by each conidiophore type and their dispersion distance, suggesting that conidiophore architectural phenotype may impact N. crassa colonization capacity.

A USER-FRIENDLY REMOTE-SENSING WEB-PLATFORM FOR BIODIVERSITY CONSERVATION AND MANAGEMENT IN PROTECTED AREAS

Abstract. The Chilean SNASPE is a complex network of 104 protected areas covering 18.5 million hectares of continental and insular Chile in South America. The geographical complexity and high biodiversity of the SNASPE make difficult to develop a unified monitoring system for conservation and management. In this contribution, we introduce a novel and remote-sensing web-platform for monitoring SNASPE units based completely in open acces data and software. The platform was designed in close cooperation with the Chilean forest service CONAF in order to make it applicable to the whole SNASPE. Following the framework of the Group on Earth Observation - Biodiversity Observation Network (GEO-BON), we used the Essential Biodiversity Variable (EBV) Phenology and MODIS Enhanced Vegetation Index (EVI) data to detect in near-real-time anomalies from the normal annual phenological cycle of vegetation. The platform is based on a flexible non-parametric probabilistic algorithm (the “npphen” R package) capable to reconstruct any type of leaf phenology and to quantify its inter-annual variation by means of confidence intervals around the most probable annual curve. Phenological anomalies are then calculated as a deviation from the expected annual cycle and judged based on their location within the confidence intervals. Anomalies located above 95% confidence interval trigger a “red alert” which is displayed on the web application as soon as the MODIS data become available. This user-friendly platform was implemented in the La Campana National Park giving early alerts of a severe drought in 2019, warning Conaf to implement actions to protect the park from potential wild fires.

Field management of Rotylenchulus reniformis on pineapple combining crop rotation, chemical-mediated induced resistance and endophytic bacterial inoculation

In Martinique or La Réunion, French authorities recently banned the use of pesticides for the management of “soil-borne pathogens” on pineapple after several decades of intensive monoculture where the natural balance between beneficial and harmful communities of soil organisms has disappeared. Today, increasing infestation of pineapple by the nematode R. reniformis and other “soil-borne pathogens” causes severe damage to the crop. New cropping systems with innovative ecological nematode management are needed. An eco-friendly cropping system, which comprised rotation of sunn hemp (C. juncea), pineapple, a natural grass fallow and another cash crop, eggplant, consistently reduced the inoculum of nematodes. Nematode populations were reduced by 86.4%, 82% and 46.5% respectively under pineapple, sunn hemp and grass fallow compared to infestations of eggplant (3456 nematodes .100g-1 of soil) after several rotations. Integrating a chemical induction of systemic resistance or application of an endophytic bacteria recovered from pineapple roots, Bacillus sp. GVS2, helped maintain low populations of nematodes during the vegetative cycle. On two pineapple varieties, MD2 and Victoria (Queen), two different treatments were applied monthly in the field, methyl jasmonate (10−4 M, 10 ml per plant), or a suspension of Bacillus sp. GVS2 (108 CFU ml−1, 10 ml per plant) isolated from pineapple roots. After eight months, the nematode populations were reduced respectively on MD2 and Victoria (Queen) by 58.3% and 50.3% with the methyl jasmonate and by 59.6% and 54.3% with the Bacillus sp. GVS2 compared to controls. Because of the efficiency of sunn hemp in reducing the inoculum of nematodes, no significant differences in vegetative growth were observed using the D leaf weight and the estimated root length densities (RLD). The potential of pest management through eco-friendly cropping systems for pineapple with a biocontrol for nematodes with no pesticide is discussed.

Investigation of the effects of non-living mulches and metribuzin on redroot pigweed and lamb'squarters in tomato

ABSTRACT-A field study was conducted to determine the influences of six mulch materials (organic and inorganic), including black plastic, transparent plastic, wheat straw, peat moss, coco peat, and sawdust and the metribuzin on the two weed species vegetative and reproductive growth cycles in a tomato field using a randomized complete block design with three replications at the Research Station of the Agricultural School, Shiraz University, Shiraz, Iran. According to the results of the analysis of variance, all evaluated traits of both weed species, and also tomato, were significantly influenced by treatments at p < 0.01.The longest and shortest time of redroot pigweed (Amaranthus retroflexus L.) emergence were recorded under the plastic mulch treatments at 28 days after transplanting (DAT) and organic mulches as well as metribuzin at 21 DAT, respectively. Plastic mulches deferred the time of lamb's quarters (Chenopodium album L.) emergence more than organic mulches up to 28.0%. Additionally, the longest time of lamb'squarters emergence was observed with coco peat at 29 DAT and the shortest time of its emergence was recorded under the application of clear plastic and sawdust mulches at 23.3 DAT. Results showed that, the highest marketable tomato yield (up to 19.2 kg m-2) was assessed in covered plots with black plastic mulch, while the lowest marketable yield was detected by 3.02 kg m-2 in the plots under the application of the sawdust treatment. In general, results demonstrated that the plastic mulches, particularly the black plastic sheet, could be reliable alternatives for metribuzin to control weed infestations in tomato fields.

Biomass accumulation, extraction and nutrient use efficiency by cover crops

The high biomass production of certain cover crops species is due to their high absorption capacity and nutrients use efficiency. Its potential for biomass production it is important to obtain productive plants using nutritional information especially in environments with low nutrient apport. The objective was to evaluate the biomass accumulation, extraction and nutrient use efficiency by cover crops growing in a soil of low fertility. The treatments were arranged in four randomized blocks, composed of seven cover crops: sunn hemp, spectabilis, pigeon pea forage, pigeon pea arbore, lab lab, jack bean and mucuna. To evaluate dry mass accumulation, crop growth rate and leaf area index, six plants were used in different times: 30, 45, 60, 75, 90 and 105 days after sowing. The cover crops differed in vegetative cycle, dry mass accumulation, yield, extraction and nutrient use efficiency, with better performance presented by pigeon pea arbore. The cover crops are good recyclers of nutrients, particularly nitrogen, potassium and calcium and have potential for use in the cultivation systems in the Northeast of Brazil.

GROWTH PARTICULARITIES OF AMERICAN POKEWEED – PLANT WITH MULTIPURPOSE UTILIZATION

American pokeweed (Phytolacca americana L.) is a good ornamental plant due to its ability to grow rapidly, broad and tall vegetation, and attractive grape-like fruits. However, American pokeweed and some useful chemical constituents, which accumulate in different parts of this plant, until present, in our opinion, are not utilised sufficient effectively. The leaves and seeds of Phytolacca americana L. produce pokeweed antiviral protein with increased antiviral and antifungal activities. Natural dyes accumulated in fruits can be used in the food, cosmetic, pharmaceutical and textile industries. The purpose of this work was to study the growth particularities of pokeweed plants propagated by seeds, and to establish the content and antioxidant activity of main constituents (polyphenols and colorant substances) in ripe fruits. American pokeweed demonstrated the excellent adaptivity of seeds and seedlings under different condition of germination, transplantation and cultivation. In season of 2019, the vegetation cycle of Phytolacca americana L. annual plants continued maximal 210 days (from March to November). The biometrical indexes of stems, racemes, fruits and seeds corresponded to similar characters reported by other scientists. The aqueous and hydroalcoholic extracts were obtained from ripe fresh fruits. The biggest amount of polyphenolic and colorant substances was found in aqueous extracts. The antioxidant activity of Phytolacca americana L. fruit extracts, evaluated in vitro by potentiometric procedure against the peroxyl free radicals, was in direct proportion to the content of polyphenols (r2=0.9563) and colorant substances (r2=0.9808). The colorant substances from American pokeweed fruits possessed the high antioxidant activity, IC50 was equal to 259.65±2.60mg/l.

Efficacy of UV-C Disinfection in Hyperbaric Chambers

Background: UV-C light reduces contamination of high-touch clinical surfaces. Few studies have tested the relative efficacy of UV-C devices in real-world clinical environments. Methods: We assessed the efficacy of the Tru-D (SmartUVC) and Moonbeam-3 UV-C (Diversey) devices at eradicating important clinical pathogens in 2 hyperbaric chambers at a tertiary-care hospital. Formica sheets were inoculated with 106–107 CFU of MRSA (USA300) or 104–105 CFU of C. difficile (NAP1). Sheets were placed in 6 predetermined locations throughout the chambers. Two Moonbeam-3 UV-C devices were positioned in the center of each chamber and were run for 3-minute (per manufacturer’s instructions) and 5-minute cycles. One Tru-D was positioned in the center of the chamber and was run on the vegetative cycle for MRSA and the spore cycle for C. difficile. UV-C dosage was measured for both machines. Quantitative cultures were collected using Rodac plates with DE neutralizing agar and were incubated at 37C for 48 hours. C. difficile was likewise plated onto sheep’s blood agar. Results: We ran each combination of chamber, microbe, and UV-C device in triplicate for In total, 108 samples per species. For MRSA, the Tru-D vegetative cycle, the 5-minute Moonbeam cycle, and the 3-minute Moonbeam cycle resulted in average CFU log10 reductions of 7.02 (95% CI, 7.02–7.02), 6.99 (95% CI, 6.95–7.02), and 6.58 (95% CI, 6.37–6.79), respectively (Fig. 1). The Tru-D vegetative and 5-minute Moonbeam cycles were similarly effective (P &gt; .99), and both were more effective than the 3-minute Moonbeam cycle (P &lt; .001 and P &lt; .001, respectively). MRSA samples receiving direct UV-C exposure had significantly greater log10 reductions (6.95; 95% CI, 6.89–7.01) than did indirect exposure (6.67; 95% CI, 6.46–6.87; P &lt; .05) (Fig. 2). For C. difficile, the Tru-D sporicidal, the 5-, and 3-minute Moonbeam cycles resulted in average CFU log10 reductions of 1.78 (95% CI, 1.43–2.12), 0.57 (95% CI, 0.33–0.81) and 0.64 (95% CI, 0.42–0.86), respectively (Fig. 1). Tru-D was significantly more effective than either the 3- or 5-minute Moonbeam cycles (P &lt; .00). C. difficile samples receiving direct UV-C exposure had higher dosage and significantly greater log10 reductions (1.34; 95% CI, 1.10–1.58) than did indirect exposure (0.58; 95% CI, 0.31–0.86; P &lt; .01) (Fig. 2). Conclusions: Use of the Tru-D vegetative cycle and the Moonbeam 3- and 5-minute cycles resulted in similar reductions in MRSA; both resulted in significantly greater reductions than the manufacturer’s recommended 3-minute Moonbeam cycle. Therefore, healthcare facilities should carefully evaluate manufacturer-recommended run times in their specific clinical setting. For C. difficile, the Tru-D sporicidal cycle was significantly more effective than either of the Moonbeam cycles, likely due to higher irradiation levels. As such, direct UV-C exposure resulted in greater average reductions than indirect exposure.Funding: NoneDisclosures: None

Inactivation of Candida auris and Candida albicans by Ultraviolet-C

Background:Candida auris is an emerging fungal pathogen that is often resistant to major classes of antifungal drugs. It is considered a serious global health threat because it has caused severe infections with frequent mortality in over a dozen countries. C. auris can survive on healthcare environmental surfaces for at least 7 days, and it causes outbreaks in healthcare facilities. C. auris has an environmental route of transmission. Thus, infection prevention strategies, such as surface disinfection and room decontamination technologies (eg, ultraviolet [UV-C] light), will be essential to controlling transmission. Unfortunately, data are limited regarding the activity of UV-C to inactivate this pathogen. In this study, a UV-C device was evaluated for its antimicrobial activity against C. auris and C. albicans. Methods: We tested the antifungal activity of a single UV-C device using the vegetative bacteria cycle, which delivers a reflected dose of 12,000 µW/cm2. This testing was performed using Formica sheets (7.6 × 7.6 cm; 3 × 3 inches). The carriers were inoculated with C. auris or C. albicans and placed horizontal on the surface or vertical (ie, perpendicular) to the vertical UV-C lamp and at a distance from 1. 2 m (~4 ft) to 2.4 m (~8 ft). Results: Direct UV-C, with or without FCS (log10 reduction 4.57 and 4.45, respectively), exhibited a higher log10 reduction than indirect UV-C for C. auris (log10 reduction 2.41 and 1.96, respectively), which was statistically significant (Fig. 1 and Table 1). For C. albicans, although direct UV-C had a higher log10 reduction (log10 reduction with and without FCS, 5.26 and 5.07, respectively) compared to indirect exposure (log10 reduction with and without FCS, 3.96 and 3.56, respectively), this difference was not statistically significant. The vertical UV had statistically higher log10 reductions than horizontal UV against C. auris and C. albicans with FCS and without FCS. For example, for C. auris with FCS the log10 reduction for vertical surfaces was 4.92 (95% CI 3.79, 6.04) and for horizontal surfaces the log10 reduction was 2.87 (95% CI, 2.36–3.38). Conclusions:C. auris can be inactivated on environmental surfaces by UV-C as long as factors that affect inactivation are optimized (eg, exposure time). These data and other published UV-C data should be used in developing cycle parameters that prevent contaminated surfaces from being a source of acquisition by staff or patients of this globally emerging pathogen.Funding: NoneDisclosures: None

Pyk2 Regulates Human Papillomavirus Replication by Tyrosine Phosphorylation of the E2 Protein

The human papillomavirus (HPV) E2 protein is a key regulator of viral transcription and replication. In this study, we demonstrate that the nonreceptor tyrosine kinase Pyk2 phosphorylates tyrosine 131 in the E2 transactivation domain. Both depletion of Pyk2 and treatment with a Pyk2 kinase inhibitor increased viral DNA content in keratinocytes that maintain viral episomes. The tyrosine-to-glutamic acid (E) mutant Y131E, which may mimic phosphotyrosine, failed to stimulate transient DNA replication, and genomes with this mutation were unable to establish stable episomes in keratinocytes. Using coimmunoprecipitation assays, we demonstrate that the Y131E is defective for binding to the C-terminal motif (CTM) of Bromodomain-containing protein 4 (Brd4). These data imply that HPV replication depends on E2 Y131 interaction with the pTEFb binding domain of Brd4.IMPORTANCE Human papillomaviruses are the major causative agents of cervical, oral, and anal cancers. The present study demonstrates that the Pyk2 tyrosine kinase phosphorylates E2 at tyrosine 131, interfering with genome replication. We provide evidence that phosphorylation of E2 prevents binding to the Brd4-CTM. Our findings add to the understanding of molecular pathways utilized by the virus during its vegetative life cycle and offers insights into the host-virus interactome.

First phenological and aerobiological assessment of olive orchards at the Northern limit of the Mediterranean bioclimatic area

An increase in the cultivation of olive trees was prompted in the Northwestern Spain during recent years favored by the agricultural politics in the region. The aim of this study is to know the phenological and aerobiological behavior of the olive trees at the northern limit of the Mediterranean bioclimatic area in order to determine their thermal requirements for the development of predictive agro-phenological models for two varieties (Arbequina and Frantoio) of the new olive cultivated areas. The BBCH scale was used for the phenological observations. Chill accumulation during dormancy and heat requirements to overcome the successive phenological stages were calculated following different methods. To complete the phenology predictive models, the Mitscherlich’s monomolecular equation was applied. The monitoring of the atmospheric pollen content was conducted by means a volumetric pollen Hirst trap placed in the middle of the plot. The period of chilling accumulation was completed during the first fortnight of January with an average of 654 chilling hours and a base temperature of 7.5 °C. Considering the duration of the vegetative olive cycle around 2390°GDD (growing degree days) was necessary to overcome the ripening of berries. The proposed model for the prediction of the successive ecological events showed a deviation between 1.5 and 3.5 days on the phenological scale. The presence of Olea pollen grains in the atmosphere of the olive grove was registered during stage 5 and stage 6 (flowering). The Hybrid Single Particle Lagrangian Integrated Trajectory Models confirmed that pollen peaks during the previous days to the flowering stage came from the extensive olive groves of the Northern Portugal which flowers some days in advance.

Trees, ground vegetation, sidewalks, cycleways: users’ preferences and economic values for different elements of an urban street—a case study in Taipei

Streets are an essential element of cities, and their design has a profound impact on their functionality to the movement of people and their well-being. This paper investigates preferences for and economic values of several street design characteristics, encompassing greenspaces (ground vegetation, trees, flowers), and walking and cycling infrastructure. A discrete choice experiment on a single case study street in Taipei, Taiwan, has revealed positive preferences for ground vegetation (and a willingness to pay—WTP—between $2.8 and $4 per year for a 1% increase in coverage), separated cycling infrastructure (with a WTP between $60 and $100 for cycleways separated from traffic), pedestrian access to road islands (WTP of $55), and the (reduced) amount of space dedicated to motor vehicles (WTP of $29 to avoid any increase). Flowers were also deemed important, but a mixed picture was obtained with respect to preference for street trees. The analysis is exploratory, on a relatively small sample of street users, but contributes to the literature on the importance of urban vegetation and walking and cycling infrastructure when designing streets and be used to draw lessons for other similarly dense urban areas in the country and wider region.

Influencia del niño oscilación del sur sobre el rendimiento de maíz de temporal en Nayarit

En México el fenómeno de El Niño Oscilación del Sur (ENSO) en inglés, incide sobre las condiciones meteorológicas y en consecuencia sobre el comportamiento de los cultivos en especial del maíz de temporal. Para la región productora de maíz de temporal en el estado de Nayarit, no se dispone de antecedentes que dimensionen esta influencia. El objetivo de esta investigación fue conocer el impacto de las fases del ENSO sobre algunas variables meteorológicas durante el ciclo vegetativo del maíz y el grado de vulnerabilidad sobre el rendimiento de grano. Se utilizó una base de datos fenológica de 15 años de registros de evaluaciones de variedades comerciales de maíz. Cuantificándose la precipitación pluvial, días húmedos, evapotranspiración potencial y grados días de desarrollo durante el ciclo vegetativo del cultivo, agrupando los datos por fase del ENSO ‘El Niño’, ‘Neutro’ y ‘La Niña’. Aunado a un análisis del rendimiento y su vulnerabilidad a la variabilidad climática. Fue ampliamente identificada la influencia en la precipitación y temperatura del aire (grados día de desarrollo) las cuales son importantes para el desarrollo del maíz en temporal. En eventos ‘Niña’ la precipitación es 28.6% más alta que en fase ‘Niño’, contrario a los grados día de desarrollo, donde en fase ‘Niño’ se acumula 6.3% más que en ‘Neutro’ o ‘Niña’. Lo anterior, explica el comportamiento del rendimiento de variedades precoces en fase ‘Niño’ (superiores a 8 t ha-1) y deja en claro como la vulnerabilidad de este cultivo puede disminuir si se dispone de semilla adecuada para cada fase del ENSO.

Automatic Grapevine Trunk Detection on UAV-Based Point Cloud

The optimisation of vineyards management requires efficient and automated methods able to identify individual plants. In the last few years, Unmanned Aerial Vehicles (UAVs) have become one of the main sources of remote sensing information for Precision Viticulture (PV) applications. In fact, high resolution UAV-based imagery offers a unique capability for modelling plant’s structure making possible the recognition of significant geometrical features in photogrammetric point clouds. Despite the proliferation of innovative technologies in viticulture, the identification of individual grapevines relies on image-based segmentation techniques. In that way, grapevine and non-grapevine features are separated and individual plants are estimated usually considering a fixed distance between them. In this study, an automatic method for grapevine trunk detection, using 3D point cloud data, is presented. The proposed method focuses on the recognition of key geometrical parameters to ensure the existence of every plant in the 3D model. The method was tested in different commercial vineyards and to push it to its limit a vineyard characterised by several missing plants along the vine rows, irregular distances between plants and occluded trunks by dense vegetation in some areas, was also used. The proposed method represents a disruption in relation to the state of the art, and is able to identify individual trunks, posts and missing plants based on the interpretation and analysis of a 3D point cloud. Moreover, a validation process was carried out allowing concluding that the method has a high performance, especially when it is applied to 3D point clouds generated in phases in which the leaves are not yet very dense (January to May). However, if correct flight parametrizations are set, the method remains effective throughout the entire vegetative cycle.

IMPACTS OF CLIMATE CHANGE SCENARIOS IN THE BRAZILIAN SEMIARID REGION ON WATERMELON CULTIVARS

ABSTRACT The phenology and water demand of crops can be altered by climate change. The objective of this study was to evaluate the impacts of climate change (temperature and relative humidity) on the development and evapotranspiration (ETc) of watermelon cultivare (Citrullus lanatus Schrad) in irrigated plantations in the Brazilian semiarid region. The experiments were conducted at the Rafael Fernandes Experimental Farm, in the municipality of Mossoró, RN, Brazil. The first experiment was carried out from February to April 2006, evaluating the cultivar Mickylee. In the second experiment, carried out from September to November 2009, the cultivar Quetzali was used. Two climate change scenarios were evaluated based on the Intergovernmental Panel on Climate Change (IPCC) report: an optimistic one named B2 and a pessimistic one named A2. It was found that climate change may cause reductions in crop vegetative cycle of 14.1 and 26.9% for the cultivar Mickylee and 7.9 and 11.1% for the cultivar Quetzali, for the optimistic and pessimistic scenarios, respectively, compared to the current climate scenario. Future climate changes will increase the watermelon crop coefficient (Kc), for the conditions under which the present study was carried out, increasing the daily ETc the total ETc, mainly for the cultivar Mickylee. Future climate changes in air temperature and relative humidity will reach limits above those tolerated by the crop, which will lead to changes in the cultural practices and irrigation management.

Control of the fungi Lasiodiplodia theobromae, the causal agent of dieback, in cv. syrah grapevines

Grapevine trunk diseases are among the most important limiting factors of worldwide viticulture. In this context, we aimed to verify the effect of chemical fungicides, biological agents and plant extracts on the control of Lasiodiplodia theobromae in pruning wounds and their physiological effects in cv. Syrah grapevines. Plant extracts (clove, cinnamon, garlic, rosemary and lemongrass), commercial fungicides (difeconazole, tebuconazole, mancozeb, sulfur, pyraclostrobin, fosetyl-Al, and azoxystrobin), chitosan, Trichoderma harzianum and Bacillus subtilis were used for the in vitro trials. The protection of pruning wounds in the potted vines was studied using fosetyl-Al, tebuconazole, Trichoderma harzianum, Bacillus subtilis, garlic extract and clove extract. The experiments were carried out through two vegetative cycles: 2015/2016 and 2016/2017. The length of wood discoloration, pathogen re-isolation percentage, fresh mass of the pruning material, peroxidase activity, fluorescence, chlorophyll index, phenological stages, shoot length and leaf area were evaluated. The treatments with clove, garlic extract, tebuconazole, pyraclostrobin, mancozeb, fosetyl-Al and B. subtilis reduced mycelial growth by more than 90%. In the grapevines, the use of T. harzianum decreased the re-isolation of L. theobromae, but no differences were verified for the other plant evaluations. We concluded that the use of T. harzianum would be a potential option for wound protection without altering the physiological aspects of cv. Syrah grapevines.

Comparative Study of the Effects of Salinity on Growth, Gas Exchange, N Accumulation and Stable Isotope Signatures of Forage Oat (Avena sativa L.) Genotypes.

Identifying suitable salt stress-tolerant phenotypes based on their agronomic and physiological traits remains a herculean task in forage-type oat (Avena sativa L.) breeding. This study examined the responses of six forage-type oat cultivars under four levels of saline stress over the vegetative growth cycle. Crop growth, water status-related traits and nitrogen status-related traits were analyzed in different plant parts to evaluate effective approaches for identifying salt tolerance. Plant biomass, height, tiller number and culm thickness changed substantially during salinity, but they were not precise enough for use in estimating genotypic salinity tolerance during long-term stress. Genotypes bearing larger numbers of tillers showed greater sensitivity to salinity due to its effects on biomass loss. Tolerant genotypes exhibited higher relative shoot biomass together with higher water use efficiency. The concentrations of Na+, K+ and their ratio, combined with the δ13C in shoots and roots were effective indicators for estimating tolerant genotypes through better water maintenance. N concentrations of shoots were the most efficient for evaluating genotypic tolerance. Low nitrate reductase (NR) and glutamine synthetase (GS) activity might be key factors limiting N accumulation. Chlorophyll (Chl) content and net photosynthetic rate, as well as stomatal conductance and evaporation, were useful for identifying salinity tolerance physiological mechanisms, but the effectiveness was low for genotypic tolerance testing for forage type oats due to the interaction between genotypes and salinity levels. The selection of high salinity-tolerant genotypes should focus on genotypes with photosynthetic resilience to salt, followed by high N metabolism (higher NR and GS activities) to ensure accumulation of more N in the shoot dry matter.

OPTIMAL DATES FOR DECIDUOUS TREE SPECIES MAPPING USING FULL YEARS SENTINEL-2 TIME SERIES IN SOUTH WEST FRANCE

Abstract. The free to use Sentinel-2 (S2) sensors with 5-day revisit time at high spatial resolution in 10 spectral bands is a revolution in the remote sensing domain. Including 6 spectral bands in the near infrared, with 3 dedicated for the red-edge (where the vegetation significatively increases), these european satellites are very promising for mapping tree species distribution at a national scale. Here, we study the contribution of three one-year S2 Satellite Image Time Series (SITS) for mapping deciduous species distribution in the southwest of France. The annual cycle of vegetation (called phenology) can contribute to the identification of tree species. For some specific dates, species can have different phenological behaviours (senesence, flowering…). To train and validate the maps, we used the Support Vector Machine algorithm with a spatial cross-validation method. To train the algorithm with the same number of samples per species, we decided to undersample each class to the smallest class using a K-means clustering method. Moreover, a Sequential Feature Selection (SFS) has been implemented to detect the optimal dates per species. Our results are promising with high accuracy for Red oak andWillow (average score of the three one-year respectively F1 = 0.99, F1 = 0.94) based on the optimal dates. However, it appears that the performances when using the each full SITS are far below the optimal dates models (average ΔF1 = 0.32). We did not find, except for Willow and Red oak, that the optimal dates were the same for each year. Perspectives is to find an algorithm robust to temporal or spectral noise and to smooth the time series.

Seasonal variations of essential oils from five accessions of Mentha longifolia (L.) L. with selected chemical profiles

ABSTRACT Essential oil (EO) yield and composition of five accessions of Mentha longifolia (L.) L. (leaves) were determined throughout their vegetative cycle by GC-MS and GC-FID analysis. These accessions were selected based on TLC profiles of dichloromethane extracts from wild individuals. The profile rich in α-terpinyl acetate and 8-acetoxy carvotanacetone has not been previously reported. The maximum value of EO yield was obtained in advanced flowering stage. The major composition changes were noted at the beginning of the vegetative cycle, whereas more stability was found during the flowering stage. Thus, significant changes in the major compounds were found in some accessions: piperitone and piperitenone oxides, α-terpineol acetate and 8-acetoxy carvotanacetone, which showed a considerable increase (6.0% to 20.1%) during the vegetative growth, the same way that pulegone and piperitenone oxide in other accessions. As biological activities depend on EO composition, the knowledge of its seasonal changes should be emphasized.

Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2

The short revisit times afforded by recently-deployed optical satellite sensors that acquire 3–30 m resolution imagery provide new opportunities to study seasonal vegetation dynamics. Previous studies demonstrated a successful retrieval of phenology with Sentinel-2 for relatively stable annual growing seasons. In semi-arid East Africa however, vegetation responds rapidly to a concentration of rainfall over short periods and consequently is subject to strong interannual variability. Obtaining a sufficient density of cloud-free acquisitions to accurately describe these short vegetation cycles is therefore challenging. The objective of this study is to evaluate if data from two satellite constellations, i.e., PlanetScope (3 m resolution) and Sentinel-2 (10 m resolution), each independently allow for accurate mapping of vegetation phenology under these challenging conditions. The study area is a rangeland with bimodal seasonality located at the 128-km2 Kapiti Farm in Machakos County, Kenya. Using all the available PlanetScope and Sentinel-2 imagery between March 2017 and February 2019, we derived temporal NDVI profiles and fitted double hyperbolic tangent models (equivalent to commonly-used logistic functions), separately for the two rainy seasons locally referred to as the short and long rains. We estimated start- and end-of-season for the series using a 50% threshold between minimum and maximum levels of the modelled time series (SOS50/EOS50). We compared our estimates against those obtained from vegetation index series from two alternative sources, i.e. a) greenness chromatic coordinate (GCC) series obtained from digital repeat photography, and b) MODIS NDVI. We found that both PlanetScope and Sentinel-2 series resulted in acceptable retrievals of phenology (RMSD of ~8 days for SOS50 and ~15 days for EOS50 when compared against GCC series) suggesting that the sensors individually provide sufficient temporal detail. However, when applying the model to the entire study area, fewer spatial artefacts occurred in the PlanetScope results. This could be explained by the higher observation frequency of PlanetScope, which becomes critical during periods of persistent cloud cover. We further illustrated that PlanetScope series could differentiate the phenology of individual trees from grassland surroundings, whereby tree green-up was found to be both earlier and later than for grass, depending on location. The spatially-detailed phenology retrievals, as achieved in this study, are expected to help in better understanding climate and degradation impacts on rangeland vegetation, particularly for heterogeneous rangeland systems with large interannual variability in phenology and productivity.