Orchard Planting Research Articles

Evaluation of Farmers’ Ecological Cognition in Responses to Specialty Orchard Fruit Planting Behavior: Evidence in Shaanxi and Ningxia, China

Developing specialties in orchard fruits productions with ecological and economic benefits is a practical and effective way to guarantee eco-friendliness and increase farmers’ income in the Loess Plateau area. Therefore, to understand these factors, the study constructs an agriculture ecological cognition index from three dimensions of eco-agriculture cognitions (increase income cognition, water conservation cognition and eco-product price cognition). Our analysis was based on micro survey data from 416 farmers in Shaanxi and Ningxia, China. The study used two main econometric models, double-hurdle and Interpretative Structural Modeling (ISM), to examine the relationship and influence pathways between cognition of ecological agriculture and farmers’ specialty orchard fruit planting behavior. The results show that: (i) the cognition of eco-agriculture affects whether farmers plant specialty fruits (participation decision). The cognition of eco-agriculture increases income and the cognition of eco-product price significantly affect the scale of specialty orchard fruits planting (quantity decision). (ii) Household resource endowments influence specialty orchard fruit planting responses through ecological farming cognitions. (iii) The factors influencing the participation and quantity decisions of orchard fruit planting are significantly different. Therefore, when the government actively encourages farmers to participate in specialty orchard planting, it should fully consider the cognitive factors of ecological agriculture of the growers and develop targeted training strategies.

Land cover associations of wild bees visiting flowers in apple orchards across three geographic regions of southeast Australia

The conversion of natural vegetation to agriculture is a leading cause of biodiversity decline globally, and can impact negatively on ecosystem services such as pollination. Global meta-analyses find that crop visitation by wild pollinators increases with the amount of natural or semi-natural vegetation in the surrounding landscape. However, these studies typically test the effect of one land cover type, rather than comparing multiple land cover types, and so do not provide information about the land cover arrangements that maximize crop visitation by wild pollinators. We sampled wild bee visitors to apple flowers in 2017 and 2018, and weeds and native plants in apple orchards in 2018, along landscape gradients of native vegetation and non-crop agricultural cover (open grassy areas, grazed or ungrazed) across three widely-separate agricultural regions of southeast Australia. We compared different land cover types as predictors of wild bee visitation to apple orchards, classifying non-crop land cover as: 1) ‘natural vegetation’ (NV), 2) ‘open grassy areas’ (OGA), and 3) ‘natural vegetation plus open grassy areas’ (NVOGA). The dominant flower-visiting wild bees in apple orchards in all regions were soil-nesting species of Halictidae that appear to be capable of exploiting open areas cleared for agriculture; however, even these taxa were rare or absent from orchards in some regions and years. Wild bee visitation to apples was best predicted by OGA in 2017 (positive association), but no land cover type in 2018, while visitation to weeds and native plants increased with both OGA and NV. Comparing different ways of classifying non-crop land cover is important for identifying land management strategies that maximize crop pollination services. However, managing land cover for wild bees may have negligible impacts on apple pollination in southeast Australia where wild bees are often rare in orchards, exhibit between-year variation in land cover associations, and are vastly outnumbered by honeybees (> 90% of visits to apple flowers).

PCR-based SNP Markers for Sex Identification in Date Palm (Phoenix dactylifera L.) cv. KL1

The date palm (Phoenix dactylifera L.) is a valuable commercial plant in the Arecaceae family. It is a sweet, edible fruit containing a lot of nutrients including carbs, sugar, protein, and potassium. Maejo 36 or KL1 is a Thai date palm with excellent fresh fruit quality that is mostly grown in Thailand's northern and northeastern areas. The main issue with date palm farming is that there is no reliable way to discriminate between male and female seedlings prior to flowering, which takes 3 - 5 years after planting. An increase in the number of female date palm plants in commercial orchards may increase in date production and profitable investment. The present research aims to develop Single Nucleotide Polymorphisms (SNP) markers for the sex identification of date palm cv. KL1. The SNP markers were designed by analysis of nucleotide sequence difference from GenBank (accession number GL746268.1). The results revealed that SNP primers; PH02F - PdaNu01 (PdaNU02 or PdaNU03) - PdaNU05 used in multiplex PCR technique can precisely distinguish the sex of date palm by generating 2 different sizes of PCR-products in male plants, and only 1 size of PCR-product in female plants. This research indicates that SNP markers with multiplex-PCR technique are a high potential method for identifying the sex of date palm cv. KL1 may be used to increase female plants for cultivation at the seedling stage, which is highly beneficial for commercial date palm production. HIGHLIGHTS Date palm is currently an economic fruits crops in Thailand The sex of date palm can be identified by phenotype in flowering stage until five years after planting The amplicon patterns in male and female date palm generated by SNP marker are applicable to predict their genders at an early seedling stage The use of SNP marker is highly beneficial for commercial date palm production GRAPHICAL ABSTRACT

Fire-fallow agriculture as a sustainable cropping system for maintaining organic carbon in Mar\xe9 Loyalty Island (New Caledonia, southwest Pacific)

The Loyalty Islands are part of the French archipelago of New Caledonia in the Southwest Pacific. In these islands, Gibbsic Ferralsols (Humic) are traditionally used for fire-fallow cultivation (FFC) by the Kanak people, but the planting of perennial orchards has been encouraged over the past two decades. The impacts of this policy on soil organic carbon (SOC) are nevertheless unknown, especially in these clay-free soils in which organic matter is the main contributor to soil fertility. SOC and permanganate oxidizable organic carbon (POXC) were studied in the soils of avocado orchards, FFC, and secondary and native forests. Mean SOC stocks are particularly high, ranging between 71.9 and 194.4 MgC ha−1 in an equivalent soil mass of 2000 Mg ha−1, but they are significantly impacted by land use. Avocado farming reduced SOC stocks by about 30% compared to forest soils, even if fields were established on secondary forests that had already experienced SOC losses. In contrast, FFC did not impact them. The POXC content decreased as the degree of soil anthropization increased; however, it was less sensitive than SOC in highlighting the impacts of land use. SOC storage can be achieved through changes in agricultural practices in avocado farming, with support for farmers in transitioning from family farming to perennial cultivation and the policy management of secondary forests designed to enhance the recovery of native forests.

Molecular Identification, Biological and Reproductive Characteristics of Drosophila Suzukii Developed in Six Host Plants of Economic Importance in Iran

Currently, the spotted-wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is threatening the worldwide berry and small fruit industries, but the current control methods have many disadvantages, among them are capital intensive, require high labour and not sustainable in the long term. Therefore, to develop alternative management strategies, there were investigated several biological and reproductive characteristics of D. suzukii developed in six host plants of economic importance in Tehran-Varamin province, Iran: Clementine mandarin, Golden apple smoothie, Pears, Persimmons, Red apples, and Valencia oranges. Among the six tested hosts, pear was identified as the most favorable host for D. suzukii since it registered high daily oviposition, high percentage of egg hatching, and both a short duration of larvae and pupa stages. These results could be useful to develop management strategies, in two ways. First, to implement the reproduction of this dipteran and its main parasitoid Trichopria drosophilae (Perkins) under a mass-rearing approach, and second, to help to predict the trend and pattern of infestation in Tehran-Varamin province. Due to the high sensitivity of pear fruits to this pest, it is recommended to exercise prudence in the planting of new pear orchards, especially mixed with citrus.

Characteristics of Soil C, N, and P Stoichiometry as Affected by Land Use and Slope Position in the Three Gorges Reservoir Area, Southwest China

Land use change and slope position are commonly identified as the key factors affecting the soil organic carbon (C), total nitrogen (N), and total phosphorus (P) traits in distinct ecological scales. However, the directions of these effects are still unclear in some fragile terrestrial ecosystems. This study aimed to determine the characteristics of soil C, N, and P concentrations and stoichiometry as affected by different land uses and slope positions in a representative purple soil hillslope in Three Gorges Reservoir Area (TGRA), China, which is experiencing severe soil erosion and non-point source pollution. A total of 108 soil samples were collected from secondary forest, orchard plantation, and cropland on the upper, middle, and lower slopes, respectively. Soil C, N, and P concentrations and their stoichiometric ratios were determined. The results showed that soil C concentration was not affected by land use, while soil N and P concentrations were both the highest in orchard plantation rather than in secondary forest and cropland, resulting in the lowest C:N, C:P, and N:P ratios in the orchard plantation. Soil C and N concentrations synchronously decreased from upper slope to the lower slope, and soil P concentration was not markedly different among slope positions. This also caused the insignificant difference in soil C:N ratio and the remarkably lowest C:P and N:P ratios on the lower slope. There were significant interactive effects of land use and slope position on the study soil variables except soil P concentration. Our results highlight the effects of land use and slope position on soil C, N, and P traits and point to the decoupling of linkages between soil P and soil C as well as N due to the severe soil erosion and overuse of fertilization in the TGRA.

Metabarcoding Analysis of Pollen Species Foraged by Osmia excavata Alfken (Hymenoptera: Megachilidae) in China

To meet the pollination need of economic crops, Osmia excavata has been successfully used to improve the pollination efficiency of Rosaceae and Brassicaceae plants. As a widely used pollinator of economic crops, a systematic study of flower-visiting species and diversities of O. excavata stocked in China was not found. To investigate the foraging pollen species and diversities of O. excavata, beebread from 20 experimental plots in China was collected by the trap-nesting method and analyzed by DNA metabarcoding technology. A total of 26 pollen plants in 14 genera and nine families were identified. A further analysis showed that the richness and abundance of the wild flowering plants in orchards and farmlands were lower than those in the nearby semi-natural habitats. The favorite pollen comes from economic crops apple and rape and wild flowering plants Juncus interior, Rosa gymnocarpa, and Rosa laevigata. Through a diversity index analysis, it was found that the Anhui region has the highest pollen plant diversity, while the Liaoning region has the lowest. Our results can provide a basis for flower-visiting species and diversities of O. excavata.

Technological effectiveness of formation of planting furrow by working body of passive type of orchard planting machine

The article presents the results of experimental studies of technological effectiveness of formation of planting furrow by working body of passive type of orchard planting machine. The authors adhered to working hypothesis that to reduce energy consumption and increase the reliability of orchard planting machine in various operating conditions, possibly due to passive type of working body, which provides undercutting the soil layer and raises it to formation of planting furrow, and after placing the seedling in it, it encloses it as before area without additional significant movement or rotation. The article presents the results of study of number of roots hooks of two-year-old apple seedlings when trying to place their root system in interval between the opener model extensions. The authors presented the models of schemes of interaction between plant stems and blade of main blade and optimized the parameters of working surface of barrel blade. The authors established the dependence of additional averaged soil resistance coefficient on planting depth. The article investigates the dependence of resistance force of working body of orchard planting machine on planting depth and soil type. The authors presented the results of technological effectiveness of prototype of working body of orchard planting machine during experimental research and production tests.

Estimation of Nitrogen Content in Citrus Leaves Using Stacking Ensemble Learning

Nitrogen is an essential biochemical component of citrus growth, and also an important indication to determine the quality and yield of citrus. The traditional method to obtain Leaf Nitrogen Content (LNC) is costly and time-consuming. Therefore, the rapid and accurate acquisition of nitrogen content information by satellite remote sensing is of great significance for citrus cultivation and production. Empirical models based on vegetation indices (VIs) have been widely used to estimate LNC, while individual model only extracts limited information. The ensemble learning strategy has shown great potential in machine learning, so Landsat8 OLI satellite remote sensing images and ground sample data are used to construct a two-layer Stacking ensemble learning framework for estimating the nitrogen content of citrus leaves in this study. In the proposed model, K-Nearest Neighbors (KNN), Random Forest (RF) and Support Vector Regression (SVR) are utilized as base-models. Linear Regression (LR) is employed as the meta-model. Results show that Stacking model can obtain better estimation results of citrus LNC, thus providing scientific decision support for orchard planting and production.

Screening of Olive Biodiversity Defines Genotypes Potentially Resistant to Xylella fastidiosa.

The recent outbreak of the Olive Quick Decline Syndrome (OQDS), caused by Xylella fastidiosa subsp. pauca (Xf), is dramatically altering ecosystem services in the peninsula of Salento (Apulia Region, southeastern Italy). Here we report the accomplishment of several exploratory missions in the Salento area, resulting in the identification of thirty paucisymptomatic or asymptomatic plants in olive orchards severely affected by the OQDS. The genetic profiles of such putatively resistant plants (PRPs), assessed by a selection of ten simple sequence repeat (SSR) markers, were compared with those of 141 Mediterranean cultivars. Most (23) PRPs formed a genetic cluster (K1) with 22 Italian cultivars, including ‘Leccino’ and ‘FS17’, previously reported as resistant to Xf. The remaining PRPs displayed relatedness with genetically differentiated germplasm, including a cluster of Tunisian cultivars. Markedly lower colonization levels were observed in PRPs of the cluster K1 with respect to control plants. Field evaluation of four cultivars related to PRPs allowed the definition of partial resistance in the genotypes ‘Frantoio’ and ‘Nocellara Messinese’. Some of the PRPs identified in this study might be exploited in cultivation, or as parental clones of breeding programs. In addition, our results indicate the possibility to characterize resistance to Xf in cultivars genetically related to PRPs.

Appraisal of Carbon Capture, Storage, and Utilization Through Fruit Crops

Nowadays, rapid increases in anthropogenic activities have resulted in increased greenhouse gases (GHGs; CO2, CH4, N2O) release in the atmosphere, resulting in increased global mean temperature, aberrant precipitation patterns, and several other climate changes that affect ecological and human lives on this planet. This article reviews the adaptation and mitigation of climate change by assessing carbon capture, storage, and utilization by fruit crops. Perennial plants in forests, fruit orchards, and grasslands are efficient sinks of atmospheric carbon, whereas field crops are a great source of GHG due to soil disturbance, emission of CH4 and/or N2O from burning straw, and field management involving direct (fuel) or indirect (chemicals) emissions from fossil fuels. Thus, there is a need to establish sustainable agricultural systems that can minimize emissions and are capable of sequestering carbon within the atmosphere. Fruit orchards and vineyards have great structural characteristics, such as long life cycle; permanent organs such as trunk, branches, and roots; null soil tillage (preserving soil organic matter); high quality and yield, which allow them to accumulate a significant amount of carbon. Hence, the fruit plants have significant potential to sequester carbon in the atmosphere. However, the efficiency of carbon sequestration by different fruit crops and their management systems may vary due to their growth and development patterns, physiological behavior, biomass accumulation, and environmental factors.

Computer vision-based citrus tree detection in a cultivated environment using UAV imagery

Manual inspection has been a common application for counting the trees and plants in orchards in precision agriculture processes. However, it is a time-consuming and, labour-intensive and expensive task. Recent remote sensing tools and methods provide a revolutionizing innovation for monitoring individual trees and crop recognition as an alternative to manual detection useful for long-term agricultural management. Our study adopted a Connected Components Labeling (CCL) algorithm to detect and count the citrus trees based on the high-resolution Unmanned Air Vehicles (UAV) images in two agricultural patches. The workflow consisted of applying morphological image operation algorithms on multi-spectral, 5-banded orthophoto imagery (derived from 1560 scenes) and 3,57 cm spatial resolution. Our approach was able to count 1462 out of 1506 trees resulting in accuracy and precision higher than 95% (average Recall: 0.97, Precision: 0.95) in heterogeneous agricultural patches (multiple trees and tree sizes). According to our understanding, the first time a CCL algorithm has been used with UAV multi-spectral images for detecting citrus trees. It performed significantly for geolocation and counting the trees individually in a heterogenous orchard. We concluded that our methodology provided satisfactory performance to predict the number of trees (in the citrus case study) in dense patches. Therefore it could be promising to replace the conventional tree detection techniques to detect the orchard trees in complex agricultural regions.

Estimation of Apple Flowering Frost Loss for Fruit Yield Based on Gridded Meteorological and Remote Sensing Data in Luochuan, Shaanxi Province, China

With the increase in the frequency of extreme weather events in recent years, apple growing areas in the Loess Plateau frequently encounter frost during flowering. Accurately assessing the frost loss in orchards during the flowering period is of great significance for optimizing disaster prevention measures, market apple price regulation, agricultural insurance, and government subsidy programs. The previous research on orchard frost disasters is mainly focused on early risk warning. Therefore, to effectively quantify orchard frost loss, this paper proposes a frost loss assessment model constructed using meteorological and remote sensing information and applies this model to the regional-scale assessment of orchard fruit loss after frost. As an example, this article examines a frost event that occurred during the apple flowering period in Luochuan County, Northwestern China, on 17 April 2020. A multivariable linear regression (MLR) model was constructed based on the orchard planting years, the number of flowering days, and the chill accumulation before frost, as well as the minimum temperature and daily temperature difference on the day of frost. Then, the model simulation accuracy was verified using the leave-one-out cross-validation (LOOCV) method, and the coefficient of determination (R2), the root mean square error (RMSE), and the normalized root mean square error (NRMSE) were 0.69, 18.76%, and 18.76%, respectively. Additionally, the extended Fourier amplitude sensitivity test (EFAST) method was used for the sensitivity analysis of the model parameters. The results show that the simulated apple orchard fruit number reduction ratio is highly sensitive to the minimum temperature on the day of frost, and the chill accumulation and planting years before the frost, with sensitivity values of ≥0.74, ≥0.25, and ≥0.15, respectively. This research can not only assist governments in optimizing traditional orchard frost prevention measures and market price regulation but can also provide a reference for agricultural insurance companies to formulate plans for compensation after frost.

Physiological Disorders and Fruit Quality Attributes in Pomegranate: Effects of Meteorological Parameters, Canopy Position and Acetylsalicylic Acid Foliar Sprays.

Meteorological parameters and occurrences of cracking (CR), russeting (RS), and sun scald (SS) symptoms were monitored in a pomegranate cv. “Wonderful” orchard planted in a W–E orientation, during a 3-year study. Moreover, the efficacy of preharvest foliar sprays with acetylsalicylic acid (ASA; 0.5 mM or 1.0 mM), applied biweekly four to six times, on yield and fruit quality attributes were evaluated in a 2-year study. Fruit from the N-side of the canopy had greater CR and RS, whereas SS symptoms were lower, compared with the S-exposed part of the canopy. The N-side of the canopy had also substantially lower fruit number and yield, suggesting for an important role of light on bisexual flower formation and/or fruit set. Following the occurrences in CR and RS during the fruit maturation period, it was found that temperature fluctuation was the main cause. The presence of RS damages may also be related with increased relative humidity and water movement as symptoms were higher in years with higher values, in the N-side of the canopy and often occurred in the exposed and stylar end of the fruit. The ASA treatment substantially reduced RS by up to 57%, improved the peel red coloration, while anthocyanin, antioxidant capacity, and soluble solid contents in juice were higher. Foliar sprays with ASA did not affect yield, but induced a trend of bigger-sized fruit. In conclusion, planting in a N–S row orientation and selecting an orchard plantation site with a minimum temperature fluctuation and low relative humidity during the fruit-ripening period are measures to control CR and RS in pomegranate. ASA foliar applications proved to have beneficial effects on juice antioxidant contents, but more importantly on fruit appearance.

Operation power consumption and verification tests of a trenching device for orchards in Xinjiang based on discrete element

According to the agronomic requirements of orchard planting pattern and fertilization in Xinjiang, the soil particle models and a soil-trenching device interaction model were established by using discrete element simulation software in order to find out the law of influence of structure parameters and working parameters on the operation power consumption of a segmented cutting trenching device; moreover, its cutting process was simulated according to the response surface test design. According to the results of research on the influence of forward speed, cutter disk speed and cutter disk combination on the operation power consumption of the segmented cutting trenching device, the law of their influence on the operation power consumption in descending order is forward speed, cutter disk combination, cutter disk speed. According to the response surface test result, the following influential factor parameter combination has been obtained: forward speed 815 m/h, cutter disk speed 112 r/min, cutter disk combination A (cut angle 150°, bent angle 60° and working width 133 mm), cutter disk combination B (cut angle 180°, bent angle 90° and working width 166 mm), and trenching operation power consumption-optimization results were verified through field tests. According to the verification, the results showed a high accuracy of the simulation, with a relative error mean of 3.18% between the theoretical value and the field test value. This study can provide a reference for the energy-saving design of orchard trenching devices. Keywords: trenching device, discrete element, orchard, power consumption, simulation analysis, parameter optimization DOI: 10.25165/j.ijabe.20211401.5477 Citation: Ma C, Qi J T, Kan Z, Chen S J, Meng H W. Operation power consumption and verification tests of a trenching device for orchards in Xinjiang based on discrete element. Int J Agric & Biol Eng, 2021; 14(1): 133–141.

Comparative Analysis of the Rhizosphere and Endophytic Microbiomes across Apple Rootstock Genotypes in Replant Orchard Soils

Apple replant disease (ARD), caused by a complex of soilborne pathogens, negatively impacts tree health and productivity in new orchard plantings at sites previously planted to apple. Use of new disease-tolerant apple rootstock genotypes may diminish growth-limiting effects of ARD; however, the influence of rootstock genotype on modulating the rhizosphere and endophytic microbiome to enable ARD tolerance is not fully understood. Composition of the rhizosphere and root endophytic microbiomes was characterized across a diversity of apple rootstock genotypes. A series of tolerant (G.210, G.41, G.890, and G.935) and susceptible (M.26 and M.9) rootstock cultivars were consecutively planted into orchard replant soil containing a known pathogen complex. Amplicon sequencing was used to determine simultaneously the presence of a broad taxonomic range of organisms and their relative abundance. Microbial communities exhibited significant differences in composition between the rhizosphere and endophytic environments in terms of species diversity, content, and abundance. Significant differences in composition of the endophytic and rhizosphere microbiomes were observed between rootstock genotypes. Among rootstock endophytic fungal communities, rootstock G.890 samples consistently harbored the highest percentage of arbuscular mycorrhizal fungal species (>5% of total). Ilyonectria spp., which may function as a pathogen of apple, were detected at high relative abundance in the endosphere of all genotypes, with the highest relative abundance in M.26. These results provide further insight into rhizosphere and endophytic microbial communities of apple rootstocks, which could be exploited or manipulated to improve tree fruit agricultural management practices with respect to plant nutrition and disease control.

Поливные устройства капельного увлажнения почвы в междурядьях древесно-плодовых насаждений

Purpose: technical support for drip irrigation of the inter-row root-inhabited soil space in fruit garden plantations. Materials and methods. The object of the study was the irrigation network of perennial tree-fruit orchard plantations. During the research, analysis and variant comparison were carried out, highlighting the advantages and disadvantages of the structures under consideration. When improving the design of the drip irrigation facility, the methods of exploratory design were used. Results. During the research, the experience of operating the drip irrigation systems of perennial orchards was generalized and the basic requirements for the drip irrigation network in perennial orchards were formed. As an object for further research, partially satisfying these requirements, a constructive diagram of a drip irrigation facility for moistening the soil in the inter-row root-inhabited soil space of tree-fruit orchard plantations, given in RU Patent no. 2713136, was adopted. The disadvantage of this design of a drip irrigation facility is low reliability of the elastic coupling, which should be deformed when the position of the drip console changes, have the necessary rigidity to lift the drip console from the working position to the idle position, and be a sealed conduit connecting the drip console and the tee. As a result of the research, an improved design of the irrigation structure has been proposed, which does not include deformable elements. Conclusions. The proposed design scheme of a drip irrigation facility for perennial fruit plantations meets the requirements of manufacturability, has the ability to automatically operate in the irrigation mode and in the inter-irrigation period, and provides irrigation water supply to certain points of the location of the developed root system of perennial plants, including the inter-row root-inhabited soil space.

Successful management of limber tail syndrome in Labrador dog: First case report in India

The requisite for preliminary production of fruit crops viz., Apple, Peach, Pear, Apricot, and Cherry has become censorious as the compactness of the plants over the past half century has raised with the ameliorated management systems. For apple cultivation, dwarfing rootstocks are the pointers to alter the size of the trees, spacing and preliminary production. The other development methods which involve feathered trees, minimal pruning techniques and good knowledge on limb angle also resulted in drastic alteration in the density of apple trees. The pruning techniques and tree forms have been advanced with the knowledge on light interception and light distribution through the canopy. Dwarfing rootstocks benefit was full in case of apple and pear than the rest of the fruit crops. Even though the advanced techniques for high density planting were followed in other fruit crops, the density of the plants have not raised. Without disturbing the quality of the fruit, the concept of high density planting has increased the productivity of many fruit crops, majorly Apple. The preliminary yields of fruits will be obtained with the implementation of high density orchard planting. Even though the investment for high density orchard planting was bit high compared to conventional orchard development, the returns obtained were enormously high. This technique has the record of A Grade fruits with respect to quality as well price. Thus high density planting was recommended to improve the production, productivity and quality of the fruits.

Populations and Host/Non-Host Plants of Spittlebugs Nymphs in Olive Orchards from Northeastern Portugal.

Simple SummaryXylella fastidiosa is a serious fitopathogenic bacteria which causes severe problems in different crops and ornamental plants. This plant disease is transmitted by insect vectors being spittlebugs the most important in Europe. They are polyphagous and during their young stages feed on herbs, therefore usual recommendations for the reduction of spittlebug populations in perennial crops include the herbaceous ground cover removal. Nevertheless, this practice is undesirable in sustainable agriculture. Thus, in this work the goal was to identify vector species and their young stages preferred/not preferred plants in natural ground covers from olive groves. The study area was located in the northeast of Portugal, a region at risk of infection with X. fastidiosa. Several plants were identified as food resources for spittlebugs while some abundant plants presented low numbers of spittlebugs, providing with a new insight about potential plants for integrating ground covers without favoring the disease.The Aphrophoridae family contains important vectors of Xylella fastidiosa, a serious bacterial plant disease. In olive orchards, nymphs usually feed on the ground-cover vegetation. However, detailed information about their populations and host/non-host plants in some regions threatened by Xylella, such as the northeast of Portugal, is very limited. The goal of our work was to identify the vector species, nymphal development period, and their host and non-host herbaceous plants in olive orchards from northeastern Portugal. Ground-cover plant species hosting or not hosting nymphs were identified during the spring of 2017 to 2019 in olive orchards. Nymphal development period, nymph aggregation, and nymph’s preferred feeding height of the ground-cover plants were recorded. The most abundant Aphrophoridae species was Philaenus spumarius followed by Neophilaenus sp. Nymphs developed from April to early May and showed a low number of individuals per foam (generally between one and three). They preferred the middle part of the plants. Philaenus spumarius feeds preferentially on Asteraceae and Fabaceae, and Neophilaenus sp. on Poaceae. Some abundant plants, such as Bromus diandrus, Astragalus pelecinus, Chrysanthemum segetum, Trifolium spp., Caryophyllaceae, and Brassicaceae, were barely colonized by Aphrophoridae nymphs. This knowledge is essential for the selection of the species composition of ground-cover vegetation to minimize the presence of vectors of X. fastidiosa in olive groves.

Transcriptional and physiological analyses of reduced density in apple provide insight into the regulation involved in photosynthesis.

Different densities have a great influence on the physiological process and growth of orchard plants. Exploring the molecular basis and revealing key candidate genes for different densities management of orchard has great significance for production capacity improvement. In this study, transcriptome sequencing of apple trees was carried out at three different sampling heights to determine gene expression patterns under high density(HD) and low density(LD) and the physiological indices were measured to determine the effect of density change on plants. As a result, physiological indexes showed that the content of Chlorophyll, ACC, RUBP and PEP in the LD was apparently higher than that in control group(high density, HD). While the content of PPO and AO in the LD was noticeably lower than that in the HD. There were 3808 differentially expressed genes (DEGs) were detected between HD and LD, of which 1935, 2390 and 1108 DEGs were found in the three comparisons(middle-upper, lower-outer and lower-inner), respectively. 274 common differentially expressed genes (co-DEGs) were contained in all three comparisons. Functional enrichment and KEGG pathway analysis found these genes were involved in Carbon fixation in photosynthetic organisms, Circadian rhythm, Photosynthesis − antenna proteins, Photosynthesis, chlorophyll metabolism, Porphyrin, sugar metabolism and so on. Among these genes, LHCB family participated in photosynthesis as parts of photosystem II. In addition, SPA1, rbcL, SNRK2, MYC2, BSK, SAUR and PP2C are involved in Circadian rhythm, the expression of genes related to glycometabolism and hormone signaling pathway is also changed. The results revealed that the decrease of plant density changed the photosynthetic efficiency of leaves and the expression of photosynthesis-related genes, which provide a theoretical basis for the actual production regulation of apples.