Agriculture — Open Access Journal

Bacterial wilt, caused by Ralstonia solanacearum, is highly diverse and the identification of new sources of resistance for the incorporation of multiple and complementary resistance genes in the same cultivar is the best strategy for durable and stable resistance. The objective of this study was to screen seven accessions of cultivated eggplant (Solanum melongena L.) and 40 accessions from 12 wild relatives for resistance to two virulent R. solanacearum strains (Pss97 and Pss2016; phylotype I, race 1, biovar 3). The resistant or moderately resistant accessions were further evaluated with Pss97 in a second trial under high temperatures (and also with Pss2016 for S. anguivi accession VI050346). The resistant control EG203 was resistant to Pss97, but only moderately resistant to Pss2016. One accession of S. sisymbriifolium (SIS1) and two accessions of S. torvum (TOR2 and TOR3) were resistant or moderately resistant to Pss97 in both trials. Solanum anguivi VI050346, S. incanum accession MM577, and S. sisymbriifolium (SIS1 and SIS2) were resistant to Pss2016 in the first trial. However, S. anguivi VI050346 was susceptible in the second trial. These results are important for breeding resistant rootstocks and cultivars that can be used to manage this endemic disease. Full article

The tree is a fundamental living being. It contributes to nature and climate behaviour, as well to urban greening. It is also a source of wealth and employment. Most tree health inspection techniques are invasive or even destructive. Infrared thermography (IRT) is not invasive, and it has shown advantages when applied for inspection to trees and wood to detect deterioration or voids that could compromise its structure, stability, and durability. This study reviews the literature about IRT applied to a tree health inspection. It is framed in the context of the importance of trees for the balance of ecosystems, and the different techniques to detect tree deterioration. It highlights the difference when applied to wood or trees and the main factors that have been proven to cause disturbances in the thermal pattern of trees. The IRT, as other non-destructive methods, does not distinguish what type of damage it is, nor its causative agent. However, it enables identifying healthy and deteriorated tissues. The technology is very promising since it reveals that is efficient, fast, economical, and sustainable. Full article

Fusarium head blight (FHB or scab) economically devastates barley production. FHB is predominantly caused by Fusarium graminearum and has resulted in major reductions in the quality of barley in the United States. The most common source of economic loss is through development of potent mycotoxins in the grain, the most prominent of which, in the United States, is deoxynivalenol (DON). DON levels can be managed through a variety of techniques. This study presents the estimate of the statistical relationship among DON contamination in barley, FHB incidence and severity, and a variety of disease management techniques. Data from 22 field studies and a survey of barley producers are used to estimate the relationship. Fungicide applications reduce DON in barley in general and via complementary interactions with the barley cultivar. Genetic FHB resistance in barley varieties is an important determinant of DON levels, as well as previous crop and factors related to time and location. Taking care to avoid rotations with FHB host crops immediately prior to barley is also important to reduce DON levels in barley. These become key inputs into barley producer decisions for evaluating the economic value of adopting FHB management techniques. Full article

The present study analyzes the demand for extra virgin olive oil of Veneto region consumers in relation to some extrinsic characteristics of the oil, such as the place of production (with particular reference to the Veneto region), the designation of origin, the organic certification, the type of transformation (artisanal or industrial), and the cultivation of olive trees in landscapes that have preserved traditional forms, which are typically the result of irregular plantations or the reduced densities of plants per hectare of cultivated areas. To this aim, a discrete choice experiment was carried out that allowed us to identify the effect of each of the attributes on the choices of the interviewees and to highlight the presence of heterogeneity in consumer preferences. The analysis carried out highlights the presence of a strong segmentation of the extra virgin olive oil (EVOO) market in the Veneto region. In the estimated model, the heterogeneity of preferences is particularly relevant in the case of Protected Denomination of Origin (PDO) production, handicraft milling, and organic production. In contrast, the interviewees’ preferences appear to be very homogeneous for the Italian or Veneto EVOO. The results of our research confirm that the place of production is one of the most important clues considered by consumers when buying EVOO. This effect, however, appears to be less important in the areas where olive tree cultivation occupies only a reduced fraction of the cultivated area. In these situations, people tend to prioritize the consumption of EVOO from other regions where production is more widespread. Olive growing that preserves the traditional landscape appears to have a significant effect on consumer behavior, but only for some market segments. Full article

Pea (Pisum sativum L.) leaf chlorophyll and pigments syntheses are retarded under nutritional stress. Biochar has the potential to regulate soil nutrient supplies and optimize plant nutrient uptakes. We examine the role of Pongamia pinnata L. waste leaf biochar (PLB) in improving vegetative growth and leaf chlorophyll and accessory pigments of pea exposed to nutritional stress. Three PLB application rates (0, 1, and 2%) crossed with half (HF), and full NPK fertilizer (FF) recommended doses were applied to sandy soil field-pots (arranged in a completely randomized design). There were significant or maximum increases in plant vegetative or physiological traits, including the fresh or dry, above- and below-ground biomass weights, and photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and anthocyanin) in response to a 2%PLB + FF application (p = 0.002). Trait values also responded to 2%PLB + HF, which signified the nutrient regulatory character of PLB (p = 0.038). The PLB-driven reduction in nutritional stress resulted in diminished lycopene (antioxidant) content (p = 0.041). Therefore, we suggest that the soil application of 2%PLB + FF has the greatest impact on pea vegetative growth and leaf chlorophyll, carotenoids, anthocyanin, and lycopene contents in Pisum sativum L. Further research is recommended to investigate the relationship of PLB with soil nutrient availabilities and plant nutrient concentrations. Full article

The pollution of agricultural soils, water and plants by trace elements (TEs) in the Nile Delta Region, Egypt, is of great importance. This study aimed to investigate the spatial and seasonal variation of some TEs in the agricultural area adjacent to Kitchener Drain and to evaluate the ecological risk posed by these elements using six indices. Soil and plant samples were collected from seven sites close to the drain, while water samples were collected from the corresponding sites inside the drain during three seasons (winter, spring and fall). The results showed that all studied TEs in the soil varied seasonally and spatially among the locations around the drain. Most of the studied elements in the soil were higher in the southern and middle area around the drain. All studied elements in the soil were also higher in the winter than other seasons. Nickel and lead were almost non-detected during all seasons in plant tissues, while other elements were higher in the winter than other seasons. In contrast to the soil and plant tissues, water samples demonstrated lower or non-detected levels of TEs. The results also indicated that the values for the risk assessment indices differed among the studied TEs. Therefore, there is a risk of increasing the concentration of some metals in the study area due to anthropogenic pollution from the adjacent polluted drain through irrigation with contaminated water and spreading of contaminated dredged materials on agricultural fields. Full article

Jordan Valley area suffers from a lack of water because of the current political situation. Therefore, water distribution is being done on a periodic basis and farmers need to store water in artificial ponds on site so as to be able to irrigate their field during the anonymous days that water is not available from the main supply. However, artificial ponds may affect the environment negatively due to the plants that live in it such as algae, which attracts mosquitos and causes a bad smell. Thus, in this paper, a simple and low-cost photovoltaic based pumping system is proposed to inject a chemical material in the water of the artificial pond to get rid of algae. The proposed system consists of a pump that is powered by a photovoltaic module and pumps the proposed chemical material in the artificial pond using a rotary nozzle that is fixed on a pipe around the ponds. The system is affordable and reduces the production of the unwanted plants. As a result, the proposed system reduces chemical oxygen demand value, which is considered the main cause of algae blooming, from 7200 mg/L to 95 mg/L. The proposed product is powered by a 50 W foldable solar panel and it costs about 213 USD. Full article

Sustainable agricultural practices necessitate accurate baseline data of crop types and their detailed spatial distribution. Compared with field surveys, remote sensing has demonstrated superior performance, offering spatially explicit crop distribution in a timely manner. Recent studies have taken advantage of remote sensing time series to capture the variation in plant phenology, inferring major crop types. However, such an approach was rarely used to extract detailed, multiple crop types spanning a large area, and the impact of topography has yet to be well analyzed in mountainous regions. This study aims to answer two questions in crop type extraction: (i) Is it feasible to accurately map multiple crop types over a large mountainous area with phenology-based modeling? (ii) What are the effects of topography in such modeling? To answer the questions, phenological metrics were extracted from MODIS (Moderate Resolution Imaging Spectroradiometer) satellite time series, and the random forests classifier was used to map 12 crop types in South China (236,700 km²), featuring a subtropical monsoon climate and high topographic variation. Our study revealed promising results using MODIS EVI (Enhanced Vegetation Index) and NDVI (Normalized Difference Vegetation Index) time series, although EVI outperformed NDVI (overall accuracy: 85% versus 81%). The spectral and temporal metrics of plant phenology significantly contributed to crop identification, where the spectral information exhibited greater importance. The increase of slope led to a decrease in model accuracy in general. However, uniformly distributed tree plantations (e.g., tea-oil camellia, gum, and tea trees) being cultivated on large slopes (>15 degrees) achieved accuracies greater than 80%. Full article

Beans (Phaseolus vulgaris L.) originated on the American continent, specifically in the Mesoamerican zone, and their domestication took place independently in the Mesoamerican area and the Andean zone, giving rise to two well-differentiated genetic pools. It was also noted that the Andean wild populations originated from only a few thousand individuals from the Mesoamerican wild populations, which produced a great bottleneck in the formation of the Andean population. During centuries of cultivation in the Iberian Peninsula after its introduction in the 16th century, beans adapted to new environments, evolving numerous local landraces. Twenty-four local landraces of P. vulgaris from Spain were analyzed in the greenhouse during two consecutive seasons. From each genotype, five plants were grown and characterized for 17 quantitative and 15 qualitative traits using the International Board for Plant Genetic Resources (IBPGR) descriptors. Data were analyzed statistically by analysis of variance (ANOVA), principal component analysis (PCA), and cluster analysis. The results obtained indicate a high variability for most traits, especially those related to the yield and its components. The PCA and cluster analysis separated the landraces according to the color of the seed, the yield, and the pod and seed traits related to yield. Numerous traits exhibited interactions between the genotype and the environment. Most accessions reached higher yields in spring, in which solar radiation favors photosynthesis and, consequently, photoassimilation. The different response to the changing environment of the set of accessions studied in the present work is of great interest, and it can be exploited in breeding cultivars adapted to a broader range of environmental conditions. Full article

The potential land suitability assessment for tea is a crucial step in determining the environmental limits of sustainable tea production. The aim of this study was to assess land suitability to determine suitable agricultural land for tea crops in Sri Lanka. Climatic, topographical and soil factors assumed to influence land use were assembled and the weights of their respective contributions to land suitability for tea were assessed using the Analytical Hierarchical Process (AHP) and the Decision-Making Trail and Evaluation Laboratory (DEMATEL) model. Subsequently, all the factors were integrated to generate the potential land suitability map. The results showed that the largest part of the land in Sri Lanka was occupied by low suitability class (42.1%) and 28.5% registered an unsuitable land cover. Furthermore, 12.4% was moderately suitable, 13.9% was highly suitable and 2.5% was very highly suitable for tea cultivation. The highest proportion of “very highly suitable” areas were recorded in the Nuwara Eliya District, which accounted for 29.50% of the highest category. The model validation results showed that 92.46% of the combined “highly suitable” and “very highly suitable” modelled classes are actual current tea-growing areas, showing the overall robustness of this model and the weightings applied. This result is significant in that it provides effective approaches to enhance land-use efficiency and better management of tea production. Full article

The alley-cropping systems (ACSs), which integrate parallel tree strips at varying distances on an agricultural field can result, complementarity of resource use, in an increased land-use efficiency. Practitioners’ concerns have been directed towards the productivity of such systems given a reduced area covered by agricultural crops. The land equivalent ratio (LER) serves as a valuable productivity indicator of yield performance and land-use efficiency in ACSs, as it compares the yields achieved in monocultures to those from ACSs. Consequently, the objective of this combined experimental and simulation study was to assess the tree- and crop-yields and to derive the LER and gross energy yield for two temperate ACSs in Germany under different design scenarios, i.e., tree arrangements (lee- or wind-ward) and ratios of tree area to crop area. Both LER and gross energy yields resulted in a convex curve where the maximum values were achieved when either the tree or crop component was dominant (>75% of the land area) and minimum when these components shared similar proportions of land area. The implications of several design scenarios have been discussed in order to improve the decision-making, optimization, and adaptation of the design of ACSs with respect to site-specific characteristics. Full article

The experiments were carried out during 2012–2017. There were 5 crops in rotation: Red clover, winter wheat, pea, potato and barley undersown (us) with red clover. There were 5 cropping systems in the experimental setup: 2 conventional systems with chemical plant protection and mineral fertilizers; 3 organic systems which included winter cover crops and farm manure. The aim of the present research was to study the effect of cultivating barley undersown with red clover and the preceding winter cover crop on the soil microbial hydrolytic activity, the change in the content of soil organic carbon (SOC) and total nitrogen (N_tot) compared to the same parameters from the field that was previously under potato cultivation (forecrop of barley in the rotation). The cultivation of barley with red clover (barley (us)) had a positive impact on the soil micro-organisms activity. In organic systems the soil microbial hydrolytic activity increased on average by 19.0%, compared to the conventional systems. By cultivating barley (us) the soil microbial hydrolytic activity had a significant effect on the SOC content only in organic systems where winter cover crops were used. Organic cultivation systems had positive impact on the soil nitrogen content; N_tot in samples taken before sowing the barley (us) was higher by 17.4% and after the cultivation of barley (us) by 14.4% compared to conventional systems, as an average of experimental years. After cultivation of barley (us) with red clover the soil microbial hydrolytic activity had no effect on the soil N_tot content in either cultivation systems. Full article

Ecological intensification, based on agricultural practices that promote ecosystem services, has been recently proposed to match crop yield and environmental concerns. Two-year experiments were conducted in a Mediterranean environment. The treatments were: (i) four intensification levels (common vetch (CV), ryegrass (RG), bare soil without Nitrogen (N) fertilization (Control-N0) and with 100 kg ha⁻¹ of N fertilization (Control-N100) applied during pepper cultivation), and(ii) two soil tillage [soil tillage at 15 cm and 30 cm of soil depth (ST-15 and ST-30, respectively)]. The field experiment was disposed in a randomized block design with three replications. Cover crop, soil samples, and pepper samples were collected for analysis. Soil available nitrogen increased after soil tillage, especially in CV, which showed the highest fruit yield. The reduced soil N availability in RG decreased fruit yield and N uptake. The agro-physiological efficiency of pepper was similar in common vetch and Control-N100, while it was low in ryegrass. However, the adoption of RG increased the soil organic matter more than both control treatments, which, in turn, caused a depletion of soil organic matter. Moreover, reduced tillage practices for green manuring that both cover crops arepreferable to reduce external inputs in terms of fuel saving and farming operations. Full article

Wide span tractors have a wide transversal bar, on which different implements can be mounted, while the supporting wheels follow the set traffic-lanes. The stability of wide span tractor movement is influenced by unbroken small angular deviations and transversal displacements of the machine due to several factors. These deflections from the set trajectories affect the working implements, especially the peripheral ones, which can cut the plants if wide span tractors are used to manage row crops. In this context, it needs to consider a safeguard zone that allows to reduce the probability of contact between working implements and plants. The aim of this paper was to determine the quantitative effect of transverse displacements of the working implements and the suitable size of the aforesaid safeguard zone. The magnitude of the inner and outer displacements of the working implements depends significantly on their location in relation to the center of the wide span tractor. For working implements located outside the center of the tractor, the outer safeguard zone should be larger than the inner zone. The probability of crop damage by working implements can be reduced by automated control of wide span tractor movement. Full article

Fusarium species are known to establish manifold interactions with wild and crop plants ranging from pathogenicity to endophytism. One of the key factors involved in the regulation of such relationships is represented by the production of secondary metabolites. These include several mycotoxins, which can accumulate in foodstuffs causing severe health problems to humans and animals. In the present study, an endophytic isolate (A1021B), preliminarily ascribed to the Fusarium incarnatum-equiseti species complex (FIESC), was subjected to biochemical and molecular characterization. The metabolomic analysis of axenic cultures of A1021B detected up to 206 compounds, whose production was significantly affected by the medium composition. Among the most representative products, fusaric acid (FA), its derivatives fusarinol and 9,10-dehydro-FA, culmorin and bikaverin were detected. These results were in contrast with previous assessments reporting FIESC members as trichothecene rather than FA producers. However, molecular analysis provided a conclusive indication that A1021B actually belongs to the species Fusarium babinda. These findings highlight the importance of phylogenetic analyses of Fusarium species to avoid misleading identifications, and the opportunity to extend databases with the outcome of metabolomic investigations of strains from natural contexts. The possible contribution of endophytic strains in the differentiation of lineages with an uneven mycotoxin assortment is discussed in view of its ensuing impact on crop productions. Full article

Rhizodeposits, root exudates, and root border cells are vital components of the rhizosphere that significantly affect root colonization capacity and multiplication of rhizosphere microbes, as well as secretion of organic bioactive compounds. The rhizosphere is an ecological niche, in which beneficial bacteria compete with other microbiota for organic carbon compounds and interact with plants through root colonization activity to the soil. Some of these root-colonizing beneficial rhizobacteria also colonize endophytically and multiply inside plant roots. In the rhizosphere, these components contribute to complex physiological processes, including cell growth, cell differentiation, and suppression of plant pathogenic microbes. Understanding how rhizodeposits, root exudates, and root border cells interact in the rhizosphere in the presence of rhizobacterial populations is necessary to decipher their synergistic role for the improvement of plant health. This review highlights the diversity of plant growth-promoting rhizobacteria (PGPR) genera, their functions, and the interactions with rhizodeposits in the rhizosphere. Full article

Readily available moisture in the root zone is very important for optimum plant growth. The available techniques to determine soil moisture content have practical limitations owing to their high cost, dependence on labor, and time consumption. We have developed a prototype for automated soil moisture monitoring using a low-cost capacitive soil moisture sensor (SKU:SEN0193) for data acquisition, connected to the internet. A soil-specific calibration was performed to integrate the sensor with the automated soil moisture monitoring system. The accuracy of the soil moisture measurements was compared with those of a gravimetric method and a well-established soil moisture sensor (SM-200, Delta-T Devices Ltd, Cambridge, UK). The root-mean-square error (RMSE) of the soil water contents obtained with the SKU:SEN0193 sensor function, the SM-200 manufacturer’s function, and the SM-200 soil-specific calibration function were 0.09, 0.07, and 0.06 cm³ cm⁻³, for samples in the dry to saturated range, and 0.05, 0.08, and 0.03 cm³ cm⁻³, for samples in the field capacity range. The repeatability of the measurements recorded with the developed calibration function support the potential use of the SKU:SEN0193 sensor to minimize the risk of soil moisture stress or excess water application. Full article

A process developed at the Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB) for the supply and processing of wet-preserved fiber plants opens up new potential uses for such resources. The processing of industrial hemp into fiber materials and products thereof is undergoing experimental research along the value-added chain from the growing process through to the manufacturing of product samples. The process comprises the direct harvesting of the field-fresh hemp and the subsequent anaerobic storage of the entire plant material. Thus, process risk due to unfavorable weather conditions is prevented in contrast to common dew retting procedures. The effects of the anaerobic storage processes on the properties of the bast part of the plant material are comparable to the results of common retting procedures. Harvest storage, as well as further mechanical processing, leads to different geometrical properties compared to the bast fibers resulting from traditional post harvesting treatment and decortication. The fiber raw material obtained in this way is well suited to the production of fiberboards and the reinforcement of polymer or mineral bonded composites. The objective of this paper is to present recent research results on final products extended by a comprehensive overview of the whole supply chain in order to enable further understanding of the result influencing aspects of prior process steps. Full article

The use of thermography as a means of crop water status estimation is based on the assumption that a sufficient amount of soil moisture enables plants to transpire at potential rates resulting in cooler canopy than the surrounding air temperature. The same principle is applied in this study where the crop transpiration changes occur because of the fungal infection. The field experiment was conducted where 25 wheat genotypes were infected with Zymoseptoria tritici. The focus of this study was to predict the onset of the disease before the visual symptoms appeared on the plants. The results showed an early significant increase in the maximum temperature difference within the canopy from 1 to 7 days after inoculation (DAI). Biotic stress associated with increasing level of disease can be seen in the increasing average canopy temperature (ACT) and maximum temperature difference (MTD) and decreasing canopy temperature depression (CTD). However, only MTD (p ≤ 0.01) and CTD (p ≤ 0.05) parameters were significantly related to the disease level and can be used to predict the onset of fungal infection on wheat. The potential of thermography as a non-invasive high throughput phenotyping technique for early fungal disease detection in wheat was evident in this study. Full article