Neighboring Plants Research Articles

Mechanodetection of neighbor plants elicits adaptive leaf movements through calcium dynamics

Plants detect their neighbors via various cues, including reflected light and touching of leaf tips, which elicit upward leaf movement (hyponasty). It is currently unknown how touch is sensed and how the signal is transferred from the leaf tip to the petiole base that drives hyponasty. Here, we show that touch-induced hyponasty involves a signal transduction pathway that is distinct from light-mediated hyponasty. We found that mechanostimulation of the leaf tip upon touching causes cytosolic calcium ([Ca2+]cyt induction in leaf tip trichomes that spreads towards the petiole. Both perturbation of the calcium response and the absence of trichomes reduce touch-induced hyponasty. Finally, using plant competition assays, we show that touch-induced hyponasty is adaptive in dense stands of Arabidopsis. We thus establish a novel, adaptive mechanism regulating hyponastic leaf movement in response to mechanostimulation by neighbors in dense vegetation.

The genetic identity of neighboring plants in intraspecific mixtures modulates disease susceptibility of both wheat and rice.

Mixing crop cultivars has long been considered as a way to control epidemics at the field level and is experiencing a revival of interest in agriculture. Yet, the ability of mixing to control pests is highly variable and often unpredictable in the field. Beyond classical diversity effects such as dispersal barrier generated by genotypic diversity, several understudied processes are involved. Among them is the recently discovered neighbor-modulated susceptibility (NMS), which depicts the phenomenon that susceptibility in a given plant is affected by the presence of another healthy neighboring plant. Despite the putative tremendous importance of NMS for crop science, its occurrence and quantitative contribution to modulating susceptibility in cultivated species remains unknown. Here, in both rice and wheat inoculated in greenhouse conditions with foliar fungal pathogens considered as major threats, using more than 200 pairs of intraspecific genotype mixtures, we experimentally demonstrate the occurrence of NMS in 11% of the mixtures grown in experimental conditions that precluded any epidemics. Thus, the susceptibility of these 2 major crops results from indirect effects originating from neighboring plants. Quite remarkably, the levels of susceptibility modulated by plant-plant interactions can reach those conferred by intrinsic basal immunity. These findings open new avenues to develop more sustainable agricultural practices by engineering less susceptible crop mixtures thanks to emergent but now predictable properties of mixtures.

Diversity and biogeography of plant phyllosphere bacteria are governed by latitude-dependent mechanisms.

Predicting and managing the structure and function of plant microbiomes requires quantitative understanding of community assembly and predictive models of spatial distributions at broad geographic scales. Here, we quantified the relative contribution of abiotic and biotic factors to the assembly of phyllosphere bacterial communities, and developed spatial distribution models for keystone bacterial taxa along a latitudinal gradient, by analyzing 16S rRNA gene sequences from 1453 leaf samples taken from 329 plant species in China. We demonstrated a latitudinal gradient in phyllosphere bacterial diversity and community composition, which was mostly explained by climate and host plant factors. We found that host-related factors were increasingly important in explaining bacterial assembly at higher latitudes while nonhost factors including abiotic environments, spatial proximity and plant neighbors were more important at lower latitudes. We further showed that local plant-bacteria associations were interconnected by hub bacteria taxa to form metacommunity-level networks, and the spatial distribution of these hub taxa was controlled by hosts and spatial factors with varying importance across latitudes. For the first time, we documented a latitude-dependent importance in the driving factors of phyllosphere bacteria assembly and distribution, serving as a baseline for predicting future changes in plant phyllosphere microbiomes under global change and human activities.

КОНЦЕПЦІЯ ПОБУДОВИ СТРУКТУРНО МІНЛИВОЇ ЕЛЕКТРОЕНЕРГЕТИЧНОЇ СИСТЕМИ УКРАЇНИ

To support the sustainable functioning and development of the energy sector in the conditions of terrorist and military threats, the concept of building a structurally variable electric power system (EPS) is proposed. Structural variability is defined as the ability of the EPS to reproduce such a variety of subsystems and electrical connections between them, which enables the operator to manage the structure of the EPS and, in this way, ensure the stable operation of the electric power industry in conditions of purposeful destructive actions. The concept of a structurally changing EPS is a strategy for anticipating challenges and threats to the sustainable functioning and development of the electric power industry. In order to build a structurally variable EPS, it is proposed to create regional EPSs with their own capacities for production, storage, distribution and supply of electricity in volumes sufficient for consumption by the population, housing and communal services, transport and agriculture within each region. The establishment of the territorial dimensions of individual subsystems, i.e. regional EPS, is determined on the basis of a compromise between the necessary number of such subsystems and connections between them, which ensure the desired degree of variability of the EPS, and the capitalization levels of the regions sufficient to support investment and operating costs for the corresponding regional EPS. It is assumed that the national EPS supports the regional EPS with agreed amounts of maneuvering and reserve capacities and ensures the supply of electricity to enterprises of industrial, construction, transport and other types of economic activity that are of national importance and do not join the regional EPS. In cases of destruction of individual regional power plants, the national power plant, as well as undamaged neighboring regional power plants, together provide the electricity needs of the affected regions. In the structurally variable EPS, uniform rules of behavior of all energy companies as market participants interacting at the national and regional levels should apply. For the organization of such interaction, it is proposed to apply the decomposition of trading platforms and form a distributed electricity market from interconnected upper-level electricity market and regional electricity markets. References 12, figures 6.

Phenolic acid-induced phase separation and translation inhibition mediate plant interspecific competition.

Phenolic acids (PAs) secreted by donor plants suppress the growth of their susceptible plant neighbours. However, how structurally diverse ensembles of PAs are perceived by plants to mediate interspecific competition remains a mystery. Here we show that a plant stress granule (SG) marker, RNA-BINDING PROTEIN 47B (RBP47B), is a sensor of PAs in Arabidopsis. PAs, including salicylic acid, 4-hydroxybenzoic acid, protocatechuic acid and so on, directly bind RBP47B, promote its phase separation and trigger SG formation accompanied by global translation inhibition. Salicylic acid-induced global translation inhibition depends on RBP47 family members. RBP47s regulate the proteome rather than the absolute quantity of SG. The rbp47 quadruple mutant shows a reduced sensitivity to the inhibitory effect of the PA mixture as well as to that of PA-rich rice when tested in a co-culturing ecosystem. In this Article, we identified the long sought-after PA sensor as RBP47B and illustrated that PA-induced SG-mediated translational inhibition was one of the PA perception mechanisms.

Responses of three invasive alien aquatic plant species to climate warming and plant density.

Climate warming may impact plant invasion success directly, as well as indirectly through changes among interactions within plant communities. However, the responses of invasive alien aquatic species to plant density and rising temperatures remain largely unknown. We tested the effects of plant density and neighbour plant identity at different temperatures to better understand the performance of a community of invasive species exposed to climate warming. A microcosm experiment was conducted with three invasive aquatic plants species-Elodea canadensis, Egeria densa and Lagarosiphon major-, at mono and polycultures with low and high plant density, at 16°C, 19°C and 23°C. The results clearly demonstrated that rising temperature influenced, either as a single parameter or as a combined factor, at least one of the measured traits of the three invasive species. Leaf area of E. densa, root number of L. major and growth of E. densa and L. major were influenced by temperature, plant density and neighbour identity. Plant density influenced all traits with the exception of leaf area of E. canadensis and lateral branch production of E. densa. Neighbour identity had no effect on growth rate and leaf area of E. canadensis, on lateral branch and roots production of E. densa and on leaf area of L. major. These findings establish that rising temperature could enhance competition or facilitation among E. canadensis, L. major and E. densa and could cancel the beneficial effects of the presence of a neighbour species; however, the magnitude of this effect was strongly dependent on plant density. Rising temperature due to climate change will likely play a crucial role in interactions between invasive species within plant communities and in the further spread of these invasive aquatic plants.

Pharmaceutical study of Vasa (Adhatoda vasica Linn.) With special reference to its different dosage forms

Introduction: Adhatoda vasica Linn., a significant quinazoline alkaloid found in the neighboring plant linn, is the source of the drug bromhexine. The Sanskrit phrase "namoolam anaushadham" comes to mind. However, it describes pharmacological activity rather differently from other modern disciplines. Sometimes the Ayurvedic indication for a plant corresponds to the current medical indication for that plant's metabolite or derivatives of metabolites. But frequently, it indicates something that cannot be explained by an active principle. Investigating a medicinal plant's many applications can serve as a foundation for a deeper knowledge of that plant. Aim: This review is a sincere attempt to cover the many aspects of Vasa. The outcome of this study is intended to add a new stage to the process of creating preparations that contain vasa. Material and Method: For the current review, Bhaishajya kalpana texts, E-books, research journals, and dissertations were searched, and the data was collected and merged. Vasa is used as a primary medication as well as a major component in a variety of formulations. Result and Discussion: On search vasa is formulations are found in various dosage forms either as primary medication or compound preparation like swarasa, kalka, kwath, ghrita, taila, asava – arishta, granules, modak, guggulu, khanda are included in present review. All dosage forms all useful in various disease conditions according to vaya, kala, prakriti etc. It is a substance that has attracted notice due to its usage in many kalpanas, and virtually every kalpana of this medication is present in classics of ancient literature that draws attention to its utility in various kalpanas.

Belowground facilitation of plant mixtures on rhizosphere soil of Commelina communis grown on extremely Cu- and Cd-contaminated mine: From soil quality to bacterial community

Plant–plant interactions exert positive effects under stress conditions, but their impact on heavy metal-contaminated rhizosphere soil quality and bacterial community remains unclear. In this work, the rhizospheric soil of Cu-accumulator Commelina communis and neighboring plants grown in a heavily contaminated copper mine was analyzed to elucidate such belowground facilitation. Physicochemical properties and microbial characteristics of rhizospheric soil of control C. communis (far from neighboring plants), facilitated C. communis (near neighboring plants), and neighboring plants were compared. The average values of total organic carbon, NH4+-N, NO2−-N, NO3−-N, available phosphorus, urease, and phosphatase in the C. communis rhizosphere increased by 0.82-, 0.64-, 0.44-, 0.06-, 0.10-, 0.36-, and 0.30-fold in the presence of surrounding plants, respectively. The relative abundance of oligotrophic bacteria (Chloroflexi) decreased, whereas copiotrophic bacteria (Proteobacteria) increased in plant species mixtures. Venn graph and partial least squares discriminant analysis indicated that the composition of the bacterial community in the facilitated C. communis rhizosphere showed higher similarity to neighboring plants than to control C. communis. Among 49 predicted functional groups analyzed by FAPROTAX analysis, chemoheterotrophy (36.04 %) involved in carbon cycles had the highest relative abundance and increased in the facilitated C. communis rhizosphere due to the positive response of 193 OTUs (mainly belonging to Proteobacteria and Actinobacteriota) under plant–plant interactions. The increased relative abundance of Methylocella and Bradyrhizobium resulted in improved nitrogen fixation in the C. communis rhizosphere, whereas nitrate reduction with its main performer Rubrobacter was inhibited. The ecological function of rhizobiomes of the facilitated C. communis and neighbors also showed higher similarity compared with that of the control C. communis. These results show the role of neighboring plants in modulating soil quality and rhizobiomes of plant remediators under stress and more indoor garden experiments need to be conducted to verify such belowground facilitation.

An Insight of Parasitic Weeds in Africa and Scientific Developments: A Review

Parasitic weeds are a major threat to food security in Africa and control measures mostly done by smallholder farmers are not effective in eradicating the parasites. This results in a yield loss up to 100%. Parasitic weeds comprise Alectra vogelii, Striga spp., Orobanche spp., Rafflesia spp., and Phoradendron spp. Parasitic attachment is successful when three necessary conditions have been fulfilled namely the compatible host, suitable environment, and parasitic weed. These species parasite plant species through special attachment features such as modified leaves, suckers, haustoria, or modified roots. In Africa, the variability of parasitic weeds is largely driven by environmental factors such as temperature, rainfall, soil type, and crop husbandry practices. Warmer temperatures create more hospitable conditions for certain parasitic weeds, and allowing them to spread to new areas. Parasitic weed control is vital for effective crop production and the control strategies can be achieved through integrated weed control method that embraces mechanical, cultural, chemical, and biological methods. However, the most effective and crucial method is the cultivation of resistant varieties that provide long-term protection against parasitic weeds. Studies have been done on host-parasite attachment where dodder can send out new roots to infected neighbouring plants and spread their parasitic behaviour. More insight and knowledge should offer new goals for control within the life cycle of the parasitic weeds and their metabolic activities. Lastly, disciplines such as agronomy, plant breeding, nutrition, economics, and IT should play their roles effectively in combating parasitic weeds.

Genetic Evidence for Colletotrichum gloeosporioides Transmission Between the Invasive Plant Ageratina adenophora and Co-occurring Neighbor Plants.

To understand the disease-mediated invasion of exotic plants and the potential risk of disease transmission in local ecosystems, it is necessary to characterize population genetic structure and spatio-temporal dynamics of fungal community associated with both invasive and co-occurring plants. In this study, multiple genes were used to characterize the genetic diversity of 165 strains of Colletotrichum gloeosporioides species complex (CGSC) isolated from healthy leaves and symptomatic leaves of invasive plant Ageratina adenophora, as well as symptomatic leaves of its neighbor plants from eleven geographic sites in China. The data showed that these CGSC strains had a high genetic diversity in each geographic site (all Hd > 0.67 and Pi > 0.01). Haplotype diversity and nucleotide diversity varied greatly in individual gene locus: gs had the highest haplotype diversity (Hd = 0.8972), gapdh had the highest nucleotide diversity (Pi = 0.0705), and ITS had the lowest nucleotide diversity (Pi = 0.0074). Haplotypes were not clustered by geographic site, invasive age, or isolation source. AMOVA revealed that the genetic variation was mainly from within-populations, regardless of geographic or isolation origin. Both AMOVA and neutrality tests indicated these CGSC strains occurred gene exchange among geographic populations but did not experience population expansion along with A. adenophora invasion progress. Our data indicated that A. adenophora primarily accumulated these CGSC fungi in the introduced range, suggesting a high frequency of CGSC transmission between A. adenophora and co-occurring neighbor plants. This study is valuable for understanding the disease-mediated plant invasion and the potential risk of disease transmission driven by exotic plants in local ecosystems.

Responses of Planting Modes to Photosynthetic Characteristics and Fluorescence Parameters of Fokienia hodginsii Seedlings in a Heterogeneous Nutrient Environment

Fokienia hodginsii seedlings tend to vary significantly in response to differences in the surrounding environment, especially when the nutrient environment is heterogeneous and neighboring plants are in competition. Plant physiological differences occur not only in the root system, but also in the photosynthetic characteristics and fluorescence parameters of the leaves. Therefore, in this experiment, three planting modes (single planting, pure planting of F. hodginsii and mixed planting of F. hodginsii and Cunninghamia lanceolata) were set up to simulate different competition patterns. Three heterogeneous nutrient environments (N, P, K heterogeneous nutrient environment) were planted in this experiment, and the homogeneous environments were used as controls to determine the differences in photosynthetic characteristics, fluorescence parameters and the interaction of different environmental factors on each index in different heterogeneous nutrient and planting environments. The interactions of different environmental factors with various indicators were measured. In addition, all treatment combinations were evaluated and ranked by principal components analysis. The results showed that the net photosynthetic rate (Pn) was on average 28.8% and 22.3% higher under monoculture treatment compared to pure and mixed planting in each nutrient environment. Transpiration rate (Tr) and stomatal conductance (Gs) were the lowest under pure planting mode, and the overall mean of Tr was 27.2% and 5.5% lower than monoculture and mixed planting, respectively, and the overall mean of Gs was 36.5% and 14.7% lower, respectively. Intercellular CO2 concentration (Ci) was higher under mixed and pure planting mode than monoculture, but their overall increments were not significant. Pn, Tr and Gs values of F. hodginsii in the N and P patches were significantly higher than those in the homogeneous patches, whereas the average values of Pn, Tr and Gs in the K patches were slightly higher than those in the homogeneous patches. The average values of leaf Fo, Fv/Fm and qP in each nutrient patch under single planting were higher than those under pure and mixed planting, but most of the differences were not significant. The actual photochemical efficiency (yield), photosynthetic electron transfer rate (ETR) and Fv/Fm in N and P patches were significantly higher than those in the homogeneous patches, whereas qP and NPQ in N and P patches differed due to different planting patterns. Most fluorescence parameters in the K patches were lower than those in the homogeneous patches. Planting patterns and nutrient heterogeneity showed significant interaction effects on Pn, Gs, Yield, ETR, Fv/Fm and NPQ. The highest scores for photosynthetic characteristics and fluorescence parameters of F. hodginsii single planting were in N and P nutrient patches.

Ecological drivers of fine-scale distribution of arbuscular mycorrhizal fungi in a semiarid Mediterranean scrubland.

Arbuscular mycorrhizal (AM) fungi enhance the uptake of water and minerals by the plant hosts, alleviating plant stress. Therefore, AM fungal-plant interactions are particularly important in drylands and other stressful ecosystems. We aimed to determine the combined and independent effects of above- and below-ground plant community attributes (i.e. diversity and composition), soil heterogeneity and spatial covariates on the spatial structure of the AM fungal communities in a semiarid Mediterranean scrubland. Furthermore, we evaluated how the phylogenetic relatedness of both plants and AM fungi shapes these symbiotic relationships. We characterized the composition and diversity of AM fungal and plant communities in a dry Mediterranean scrubland taxonomically and phylogenetically, using DNA metabarcoding and a spatially explicit sampling design at the plant neighbourhood scale. The above- and below-ground plant community attributes, soil physicochemical properties and spatial variables explained unique fractions of AM fungal diversity and composition. Mainly, variations in plant composition affected the AM fungal composition and diversity. Our results also showed that particular AM fungal taxa tended to be associated with closely related plant species, suggesting the existence of a phylogenetic signal. Although soil texture, fertility and pH affected AM fungal community assembly, spatial factors had a greater influence on AM fungal community composition and diversity than soil physicochemical properties. Our results highlight that the more easily accessible above-ground vegetation is a reliable indicator of the linkages between plant roots and AM fungi. We also emphasize the importance of soil physicochemical properties in addition to below-ground plant information, while accounting for the phylogenetic relationships of both plants and fungi, because these factors improve our ability to predict the relationships between AM fungal and plant communities.

Drivers of bacterial and fungal root endophyte communities: understanding the relative influence of host plant, environment, and space

Bacterial and fungal root endophytes can impact the fitness of their host plants, but the relative importance of drivers for root endophyte communities is not well known. Host plant species, the composition and density of the surrounding plants, space, and abiotic drivers could significantly affect bacterial and fungal root endophyte communities. We investigated their influence in endophyte communities of alpine plants across a harsh high mountain landscape using high-throughput sequencing. There was less compositional overlap between fungal than bacterial root endophyte communities, with four 'cosmopolitan' bacterial OTUs found in every root sampled, but no fungal OTUs found across all samples. We found that host plant species, which included nine species from three families, explained the greatest variation in root endophyte composition for both bacterial and fungal communities. We detected similar levels of variation explained by plant neighborhood, space, and abiotic drivers on both communities, but the plant neighborhood explained less variation in fungal endophytes than expected. Overall, these findings suggest a more cosmopolitan distribution of bacterial OTUs compared to fungal OTUs, a structuring role of the plant host species for both communities, and largely similar effects of the plant neighborhood, abiotic drivers, and space on both communities.

Quantifying neighbour effects on tree growth: Are common ‘competition’ indices biased?

Abstract Interactions among neighbouring plants are key determinants of plant growth. To characterise the cumulative effect of all neighbours on the growth of a focal plant, neighbourhoods are often described by ‘competition’ indices. Common competition indices calculate the summed size of neighbour plants (focal‐independent index [FII]) whilst others include the summed ratio of the neighbour size relative to focal plant size (focal dependent). A frequently overlooked statistical artefact is that focal‐dependent indices (FDIs) may lead to biased estimates of neighbourhood effects on plant growth when growth is size dependent. Here, we conduct a literature search to determine the most common index types used to explain neighbour effects on tree growth. We then assess the ability of two common index types—focal dependent and focal independent—to correctly infer neighbourhood effects in (1) observations of tree growth in an experimental forest in south‐east Tasmania, Australia, and (2) an artificially created dataset where tree growth is unrelated to the neighbourhood. Both indices detected the competitive neighbourhood effect on tree growth observed in our own dataset but differed in their conclusion regarding neighbour effects in the simulated data. Despite the simulated dataset being generated so there was no relationship between tree growth and their neighbourhood, the FDI detected strong, competitive neighbourhood effects when intrinsic growth was incorrectly related to tree size. In contrast, when we considered the FII as the neighbourhood metric, we correctly did not detect any neighbourhood effects in the simulated data regardless of how size‐dependent growth was described. Synthesis. ‘Competition’ indices are a useful method to characterise the cumulative neighbourhood effect on plant growth; however, we demonstrate that indices which include the size of the focal plant in their calculation can be biased by an inherent relationship between tree growth and initial size. Whilst this bias typically overstates the strength of competition in determining focal tree growth, we show that it can be mitigated by correctly describing intrinsic growth. We discuss the limitations of both index types, provide recommendations for performing statistical modelling and outline how to check for accurate neighbour inference.

Trichoderma hamatum can act as an inter-plant communicator of foliar pathogen infections by colonizing the roots of nearby plants: A new inter-plant “wired communication”

Trichoderma is a genus of filamentous fungi widely studied and used as a biological control agent in agriculture. However, its ability to form fungal networks for inter-plant communication by means of the so-called inter-plant "wired communication" has not yet been addressed. In our study we used the model plant Arabidopsis thaliana, the fungus Trichoderma hamatum (isolated from Brassicaceae plants) and the pathogens Sclerotinia sclerotiorum and Xanthomonas campestris (necrotrophic fungus and hemibiotrophic bacteria, respectively). We performed different combinations of isolated/neighboring plants and root colonization/non-colonization by T. hamatum, as well as foliar infections with the pathogens. In this way, we were able to determine how, in the absence of T. hamatum, there is an inter-plant communication that induces systemic resistance in neighboring plants of plants infected by the pathogens. On the other hand, the plants colonized by T. hamatum roots show a greater systemic resistance against the pathogens. Regarding the role of T. hamatum as an inter-plant communicator, it is the result of an increase in foliar signaling by jasmonic acid (increased expression of LOX1 and VSP2 genes and decreased expression of ICS1 and PR-1 genes), antagonistically increasing root signaling by salicylic acid (increased expression of ICS1 and PR-1 genes and decreased expression of LOX1 and VSP2). This situation prevents root colonization by T. hamatum of the foliarly infected plant and leads to massive colonization of the neighboring plant, where jasmonic acid-mediated systemic defenses are induced.

Modeling of microalgal biodiesel production integrated to a sugarcane ethanol plant: Energy and exergy efficiencies and environmental impacts due to trade-offs in the usage of bagasse in the Brazilian context

The Brazilian sugarcane mills already provide significant amounts of renewable products (ethanol and bioelectricity) through self-sufficient bagasse cogeneration. Gaseous outputs of the sector can provide streams rich in biogenic carbon dioxide (CO2), suitable for the autotrophic cultivation of microalgae and aim, hereinafter, their conversion into biodiesel. This work modeled the integration of an ethanol plant with a cogeneration system, covering the enzymatic hydrolysis of bagasse and the production of microalgae biodiesel. A standard ethanol plant yielding 96 L ethanol/t cane may produce an additional 7.5–30 L microalgae biodiesel/t cane but at the expense of its energy self-sufficiency; the biorefinery must recur to fossil resources unless other biomass (besides bagasse) and coproducts by the plant's neighborhood can be exploited. The process simulation is conducted in nine cases derived from a central composite design with two factors – the fraction of bagasse destined for the hydrolysis system (x1) and the fraction of ethanol sent to produce anhydrous ethanol (x2) – and three levels for each factor (0, 50, 100%). Energy ratios between representative outputs and inputs – Net energy ratio (NER) and Fossil energy ratio (FER) –, direct CO2 emission, and exergy efficiencies were calculated as representative responses to evaluate the plant's technical and environmental efficiencies. Statistical tools (t-Student test, ANOVA, and R2) showed that the constructed models were robust and that the responses varied significantly with x1, while x2 produced mild or negligible effects. The highest achievable NER and FER were 0.83 and 2.09, respectively. The whole system resulted in a FER equal to 1 when bagasse usage is split in half between the hydrolysis and cogeneration systems. This result guarantees that the energy related to the useful products is higher than the requirements of fossil energy inputs, within an acceptable range. The optimum CO2 emission and exergy efficiency were found when 6–8% of the bagasse is hydrolyzed, which is also a range covering attractive energy ratios. The proposed integration benefits the sector, but resorting to renewable sources to supply energy deficits, developing the technological exploitation over wasted coproducts, and studying heat and mass integration of processes are highly recommended to enhance the global-system performance.

Evaluation of Ficus nitida Allelopathic Potential and the Most Efficient Application Method for Controlling Weeds Associated with Sunflower Plant

Allelopathy is a phenomenon by which plants positively or negatively affect neighboring plants by releasing allelopathic compounds. These allelochemicals are secondary metabolites found in different concentrations in shoots, roots, leaves, flowers, and even pollen grains. Allelochemicals have potential as natural bioherbicides for controlling weeds when applied in the form of extracts or through intercropping, cover cropping, and mulching. The present study was conducted to investigate the allelopathic potential of Ficus nitida leaves against Echinochloa crus-galli L. and Corchorus olitorius L weeds associated with sunflower plant via two application methods (mixing of F. nitida leaf powder with soil and foliar spray of F. nitida leaf powder alcoholic extract). Two pot experiments were carried out for the two summer seasons of 2020 and 2021 in the greenhouse of the National Research Centre (NRC), Dokki, Giza, Egypt. Nine treatments were applied in a completely randomized block design. Three treatments were applied before sowing, namely F. nitida leaf powder was mixed with the soil at rates of 15, 30, and 45 g/pot. The other three treatments of alcoholic leaf powder extract of F. nitida were sprayed twice on both plants and weeds at 10, 20, and 30% (w/v) concentrations. Additionally, three check treatments—healthy (sunflower only), unweeded, and both weeds only—were applied for comparison. The recorded results showed that F. nitida had an allelopathic bioherbicidal effect on both weeds. By increasing the concentration of F. nitida extract, the bioherbicidal potential increased. Moreover, the recorded results showed that foliar spray of alcoholic extract at 30% concentration was the superior application method for controlling weeds. Mixing of F. nitida leaf powder at 45 g/pot ranked second after this superior treatment. A noticeable result is that these two superior treatments improved sunflower growth parameters and yield traits. Quantitative estimation of phenolic compounds and flavonoids demonstrated that the concentration of these allelochemicals is higher in alcoholic extract than in water extract. Moreover, phenolic acid concentrations as detected by high-performance liquid chromatography fractionation are higher in alcoholic extract than in water extract.

Cotton topping reduces the performance of aphids on topped and neighbor plants under greenhouse conditions

Cotton topping reduces the performance of aphids on topped and neighbor plants under greenhouse conditions

A novel deep learning architecture for disease classification in Arabica coffee plants

SummarySeveral research works on disease detection in coffee plants have been presented in recent years. Leaf miner and rust are the most prevalent diseases in Arabica coffee plants. Early detection of such diseases allows farmer to take diagnostic actions before the infection spreads to neighboring plants. With advancements in drones and artificial intelligence (AI), the automatic detection of leaf diseases is gaining prominence in the field of smart agriculture. Furthermore, it is critical to develop an accurate method for infestation detection with minimal computational complexity. Existing works for plant disease detection utilize pre‐trained deep learning models with millions of parameters. A feasible trade‐off has to be attained between accuracy and computational complexity for the deployment of such deep networks. This research proposes an effective method for disease detection in Arabica coffee plants using EfficientNetB0 architecture. The architecture of the EfficientNetB0 network was improvised by including a ghost module at its end. This integration allows the network to learn effectively with minimal parameters without compensating for the end accuracy. The proposed model has a total of 4,874,531 parameters which is significantly lesser than most of the state‐of‐the‐art deep learning architectures and achieved an accuracy of 84%.

Analyzing Changes in Maize Leaves Orientation due to GxExM Using an Automatic Method from RGB Images.

The sowing pattern has an important impact on light interception efficiency in maize by determining the spatial distribution of leaves within the canopy. Leaves orientation is an important architectural trait determining maize canopies light interception. Previous studies have indicated how maize genotypes may adapt leaves orientation to avoid mutual shading with neighboring plants as a plastic response to intraspecific competition. The goal of the present study is 2-fold: firstly, to propose and validate an automatic algorithm (Automatic Leaf Azimuth Estimation from Midrib detection [ALAEM]) based on leaves midrib detection in vertical red green blue (RGB) images to describe leaves orientation at the canopy level; and secondly, to describe genotypic and environmental differences in leaves orientation in a panel of 5 maize hybrids sowing at 2 densities (6 and 12 plants.m-2) and 2 row spacing (0.4 and 0.8 m) over 2 different sites in southern France. The ALAEM algorithm was validated against insitu annotations of leaves orientation, showing a satisfactory agreement (root mean square [RMSE] error = 0.1, R2 = 0.35) in the proportion of leaves oriented perpendicular to rows direction across sowing patterns, genotypes, and sites. The results from ALAEM permitted to identify significant differences in leaves orientation associated to leaves intraspecific competition. In both experiments, a progressive increase in the proportion of leaves oriented perpendicular to the row is observed when the rectangularity of the sowing pattern increases from 1 (6 plants.m-2, 0.4 m row spacing) towards 8 (12 plants.m-2, 0.8 m row spacing). Significant differences among the 5 cultivars were found, with 2 hybrids exhibiting, systematically, a more plastic behavior with a significantly higher proportion of leaves oriented perpendicularly to avoid overlapping with neighbor plants at high rectangularity. Differences in leaves orientation were also found between experiments in a squared sowing pattern (6 plants.m-2, 0.4 m row spacing), indicating a possible contribution of illumination conditions inducing a preferential orientation toward east-west direction when intraspecific competition is low.