Walnut Research Articles

Tree Nut Crop Response to Simulated Florpyrauxifen-benzyl and Triclopyr Herbicide Drift

California is the nation’s primary producer of almonds, pistachios, and walnuts, and an important producer of rice. Because of California’s diverse cropping systems, off-target herbicide drift can be a considerable problem, particularly from aerial applications that are commonly used in flooded rice production systems. Triclopyr is an auxin-mimic type herbicide that has been commonly used in rice for many years for control of broadleaf weeds and the industry is familiar with symptoms of off-target triclopyr drift. Florpyrauxifen-benzyl is a newly registered auxin-mimic herbicide in California rice with activity on key weeds and is being rapidly adopted. Although symptoms typically are similar among auxinic herbicides, it is important to understand subtle differences and risks among these herbicides as stewardship for newly registered products. This research was conducted in 2020 and 2021 to determine the relative sensitivity of almond, pistachio, and walnut trees to simulated drift rates of florpyrauxifen-benzyl and triclopyr as well as characterize and compare symptoms caused by these two herbicides. The fractional herbicide rates tested were 1/200X, 1/100X, 1/33X, and 1/10X of the florpyrauxifen-benzyl use rate of 29.4 g·ha−1 a.i. and 1/200X, 1/100X, and 1/33X of the triclopyr use rate of 420.3 g·ha−1 a.e. Florpyrauxifen-benzyl and triclopyr herbicides were applied directly to one side of the canopy of 1- to 2-year-old almond, pistachio, and walnut trees. The general symptoms of florpyrauxifen-benzyl and triclopyr were chlorosis, chlorotic spots, leaf curling, leaf narrowing, leaf distortion, leaf malformation, leaf crinkling, shoot curling, stem coloring, stunting, terminal bud death, and twisting. The florpyrauxifen-benzyl and triclopyr injury symptoms were compared at the same fractional rates and found to be similar to each other. The herbicide injury was observed on the entire pistachio canopy, particularly on developing leaves and terminal buds. In contrast, injury symptoms on almond and walnut were more apparent on the side of the canopy to which the herbicides were applied. Symptom severity peaked at 14 days after treatment with the 1/10X florpyrauxifen-benzyl rate, when the visible injury was 16%, 48%, and 78% on almond, walnut, and pistachio, respectively. Although almond and walnut symptoms from the 1/10X florpyrauxifen-benzyl rate remained visible longer than all other treatments, all trees gradually recovered throughout the growing season. In contrast, pistachio trees did not recover fully and had injury symptoms that persisted for the remainder of the treatment year and at leaf-out the following spring. When drift occurs, it is typically at rates below 1/100X up to 1/33X of herbicide use rates. This research suggested that proper herbicide drift management practices and application precautions are likely to minimize the risk of significant injury from florpyrauxifen-benzyl drift to almond and walnut because of low injury symptoms at the typical drift rates. However, extra precautions may be needed if there are nearby pistachio orchards.

Distribution characteristics of photoassimilates in walnut leaves to different organs

The understanding of photoassimilate distribution serves as the fundamental basis for scientific regulation of fruit quality. Currently, there is a scarcity of research on whole-plant scale photoassimilate distribution in walnut. In order to clarify the characteristics of leaf photoassimilates translocation to various organs in 5-year-old 'Wen185' (J. regia 'Wen185') walnut during the growing season, this study used the 13C isotope pulse labeling technique to label the whole plant of walnut trees in the growing season, temporal variations of 13C abundance (δ13C), 13C partition rate (R13C), leaf source strength and fruit sink strength were analyzed in various organs at different days after tree flowering. The findings indicated that during the periods of 30–70 days and 90–110 days after flowering, there was a higher distribution of 13C in fruits and vegetative branches. However, at 110–130 days after flowering, the predominant allocation of 13C shifted towards main trunk and roots. In-depth study of source leaves and sink fruits showed that chlorophyll content in leaves increased significantly 30–50 days after anthesis, indicating that they gradually became mature functional leaves. The increase of net photosynthetic rate led to increase of source strength, and the retention of photoassimilates in leaves was higher at this time. From 30 to 70 days after flowering, the fresh weight and volume of fruit increased rapidly, which increased the capacity of the sink and enhanced the competition ability against photoassimilates. The recovery of photosynthetic capacity of leaves from 90 to 110 days promoted the output of photoassimilates. At this time, walnut entered the oil conversion period, and the demand for photoassimilates increased. All these factors jointly promoted the unloading of photoassimilates in fruit. In summary, maintaining adequate material conditions and optimizing tree structure at 30-70d and 90-110d after anthesis are important for more efficient distribution of photoassimilates to fruit.

New Ophiostoma species associated with Dryocoetes himalayensis and decline of Juglans regia in Czechia

AbstractA new ophiostomatoid fungus involved in the decline of walnuts was discovered in Czechia. The fungus was isolated from necrotic wood surrounding the larval galleries of Dryocoetes himalayensis, the alien bark beetle attacking walnut trees. This insect species is rather unique within hardwood-associated bark beetle species for its aggressiveness and ability to attack apparently healthy trees. The isolated fungus, associated with an exotic insect vector is described as a new species, Ophiostoma juglandis sp. nov., based on its unique morphology and phylogenetic position. The pathogenicity tests confirmed the aggressiveness of the species to both Juglans regia and J. nigra plants, manifested by formation of extensive bleeding and necrotic lesions. The symbiotic relationship between O. juglandis and D. himalayensis is expected due to massive presence of the fungal spores on surface of adult beetles in pits forming the elytral striae. In the case of hardwood-associated ophiostomatoid fungal species, phytopathogenicity is very rarely observed. The described species is exceptional in this ability, which corresponds to the aggressive behaviour of its vector. The role of the fungus in walnut tree mortality caused by D. himalayensis is discussed.

Behavioral, Physiological, and Molecular Mechanisms Underlying the Adaptation of Helicoverpa armigera to the Fruits of a Marginal Host: Walnut (Juglans regia).

In northwest China, changes in cultivation patterns and the scarcity of preferred hosts have forced Helicoverpa armigera to feed on the marginal host walnut (Juglans regia). However, the mechanisms allowing this adaptation remain poorly understood. Here, we investigated the behavioral, physiological, and molecular mechanisms underlying the local adaptation of this pest to walnut fruits. The green husk and shell generally contained higher levels of phytochemicals than the kernel. Bioassays revealed that the phytochemical-rich green husk and shell were less preferred, reduced larval fitness and growth, and elevated the activity of detoxification enzymes compared to the nutrient-rich kernel, which were further supported by a larger number of upregulated detoxification genes in insects fed green husks or shells based on transcriptome sequencing. Together, these data suggest that P450 genes (LOC110371778) may be crucial to H. armigera adaptation to the phytochemicals of walnuts. Our findings provide significant insight into the adaptation of H. armigera to walnut, an alternative host of lower quality. Meanwhile, our study provides a theoretical basis for managing resistance to H. armigera larvae in walnut trees and is instrumental in developing comprehensive integrated pest management strategies for this pest in walnut orchards and other agricultural systems.

EFFICACY OF A RANGE OF FUNGICIDES AGAINST FUNGAL DISEASES OF WALNUT IN THE SOUTHERN FRUIT-GROWING ZONE OF KAZAKHSTAN

The most widespread and effective method of protecting walnut trees from diseases is through chemical treatments. With the increasing variety of fungal pathogens affecting walnut trees in the southern zone of fruit production in Kazakhstan, there is a need to study the effectiveness of fungicides against these pathogens. Therefore, laboratory and field studies were carried out to evaluate the effectiveness of several fungicides against the most common diseases of walnut trees caused by Fusarium and Alternaria fungi. The effectiveness of fungicides with different mechanisms of action was studied for the first time. The fungicides evaluated were Score (difenoconazole, 250 g/l), Horus (cyprodinil, 750 g/kg), Stroby (kresoxim-methyl, 500 g/kg), Luna Tranquility (fluopyram, 125 g/l + pyrimethanil, 375 g/l) against walnut diseases in the southern zone of fruit cultivation in Kazakhstan. The results of both laboratory and field experiments showed that the most effective fungicide against fungal pathogens on walnut was Score (difenoconazole, 250 g/l). Stroby (kresoxim-methyl, 500 g/kg) also demonstrated over 80% biological efficacy against Alternaria alternata. The results of this study will assist local growers in managing various fungal diseases in walnut plantations.

Foliar application of biostimulants improves nutritional and bioactive quality of walnuts.

Owing to their health benefits, walnuts are attracting interest as a good option for nutritious meals, thereby promoting their production. Furthermore, the adoption of ecologically and environmentally friendly agriculture strengthens biostimulant use as a sustainable complement to traditional fertilizers. This study evaluated the effects of different foliar-applied biostimulants in walnut tree orchards, in northeastern Portugal, on walnuts' chemical composition and bioactivity. Walnut samples were rich in fat (particularly the polyunsaturated linoleic acid), dietary fiber and protein. Sucrose was the most prevalent soluble sugar, followed by glucose and fructose. Studied samples also showed an antioxidant activity comparable (or superior) to that of Trolox. Some plant biostimulants (e.g. Sprint Plus®) had a positive impact on the nutritional composition of walnuts, more specifically by boosting tocopherol levels, besides improving the bioactivity of walnut extracts against specific bacteria. Overall, this research demonstrated that important quality traits of walnuts can be improved using sustainable agricultural bioproducts and practices. © 2024 Society of Chemical Industry.

Evaluation of Pyroxasulfone Crop Safety and Weed Control for California Tree Nut Orchards

Pyroxasulfone is a very long chain fatty acid (VLCFA) inhibitor (group 15) with potential for preemergence weed control in orchard crops and would be beneficial for reducing selection pressure for resistance to more commonly used herbicides, such as glyphosate. Pyroxasulfone is registered and widely used in corn and soybeans in the United States as a solo product and in several premix formulations. However, there is limited published information on the performance and safety of pyroxasulfone in tree nut orchard systems. To assess the potential fit for pyroxasulfone in this crop sector, a series of crop safety and weed control efficacy experiments were carried out in key California orchard crops and in fallow fields with common orchard weeds. The non-crop studies were conducted near Davis, CA, to evaluate winter annual weed control with pyroxasulfone in comparison with pendimethalin and indaziflam. In addition, an irrigation incorporation experiment was conducted in summer to evaluate the effects of incorporation timing on pyroxasulfone, pendimethalin, and indaziflam efficacy as a measure of relative stability. Orchard weed control experiments were conducted in spring in an almond orchard near Arbuckle, CA, and a walnut orchard near Davis, CA. The orchard experiments included pyroxasulfone, pendimethalin, and indaziflam in various rate combinations with glufosinate. To evaluate crop safety, 2-year experiments were conducted to evaluate repeated applications of above-label rates of pyroxasulfone at 1199 g·ha−1 and S-metolachlor at 14,010 g·ha−1 on 1- to 2-year-old almond, pistachio, and walnut trees near Davis. Pyroxasulfone performed similarly to commercial standards with up to 95% control of broadleaf and grass weeds with pyroxasulfone and indaziflam providing 96% to 100% control of annual bluegrass, and pyroxasulfone (293 g·ha−1) being the only herbicide to suppress (>70%) common lambsquarters at 60 days after treatment (DAT). Other weeds controlled by pyroxasulfone include swinecress, redroot pigweed, yellow nutsedge, and Italian ryegrass. No differences were found among treatments in the incorporation timing study indicating adequate stability on the soil surface under summer conditions. Crop injury was not observed in the established orchards or the young orchard studies and there were no treatment effects on tree trunk diameter of almond, pistachio, and walnut in the 2-year crop safety experiments. These results indicate a potential for pyroxasulfone in California tree nut orchard systems that would be an additional site of action and beneficial for management of herbicide-resistant weeds in these crops.

Influence of Soil Properties on the Growth and Yield of Walnut Trees in the Hawraman Area, Sulaymaniyah-Iraq.

Influence of Soil Properties on the Growth and Yield of Walnut Trees in the Hawraman Area, Sulaymaniyah-Iraq.

Study of vibration patterns and response transfer relationships in walnut tree trunks

Fruit tree trunk is the support structure of the whole tree, carrying the task of vibration transmission to all levels of branches, fruit tree trunk vibration response to the design and optimization of the vibration harvesting device to provide guiding value. In this paper, the vibration response and harvesting test was carried out for four walnut fruit trees with different morphology and size, and the vibration transmission relationship between the excitation device and the fruit tree as well as inside the fruit tree was analyzed and studied according to the acceleration response curves at each position point under different frequencies. At the same time, the theoretical vibration pattern of the fruit tree and the measured spatial three-dimensional vibration pattern were constructed, and the response transfer law between each point of the fruit tree was further analyzed in terms of the vibration pattern and direction of each position point on the tree. The results show that the excitation response acceleration is basically no attenuation inside the device, but there is some attenuation in the clamping part due to the presence of damping pads. The vibration response in the fruit tree trunk is greater in amplitude farther from the excitation point. The phase relationship between each position point is basically the same in the theoretical vibration mode and the measured vibration mode, but there is damping in the actual fruit tree, which leads to the accumulation of phase hysteresis in the transmission of excitation parameters. The actual response trajectory is a narrow ellipse, and the different position points show different rotational relationships along the ellipse trajectory due to the growth of the fruit tree.

Detection of Paecilomyces formosus associated with declining urban forests and beetles in Iran

Urban forest trees are vital components of urban ecosystems, offering a range of benefits that are essential for improving the livability and sustainability of cities, providing numerous advantages for both the environment and public health. They enhance air quality by filtering pollutants, assist in regulating urban temperatures, and alleviate the urban heat island effect, which can result in substantial energy savings. Trees are often vulnerable to pathogens and pests that can cause significant damage. A survey of different trees in five provinces of Iran revealed a severe decline and dieback disease on woody plants. The affected trees included ailanthus, cedrus, cypress, ash, haloxylon, walnut, magnolia, black mulberry, paulownia, pine, oriental plane, apricot, wild pear, and elm trees. Samples of symptomatic branches and trunks were collected, and the causal fungal pathogen was isolated on potato dextrose agar (PDA) media. A total of 90 fungal isolates were obtained from trees (60 isolates) and insects (30 isolates) and then morphological investigations were done for all isolates. Molecular identification was confirmed through sequencing of the ITS and tub2 regions. This study reports 14 new hosts for Paecilomyces formosus in Iran and worldwide. Pathogenicity tests were conducted on detached branches of apricot, ailanthus, cypress, pine, sycamore, and walnut trees. The study showed that most isolates were pathogenic to six woody plants, and some isolates were associated with disease for eight woody plant species. Additionally, potential vectors and reservoirs for P. formosus were assessed in different beetles, including Aeolesthes sarta, Scolytus kirschii, and Orthotomicus erusus in Tehran, Alborz, Qazvin, Lorestan, and Zanjan Provinces. The results confirmed the potential of beetles for the transmission and maintenance of P. formosus.

Transcription combined metabolic analysis reveals the mechanism of potassium phosphate enhances resistance to walnut anthracnose (Colletotrichum gloeosporioides)

Given the increasingly serious diseases [anthracnose mainly caused by Colletotrichum gloeosporioides (C. gloeosporioides)] of walnut plants in recent years and the environmental pollution caused by chemical pesticides, phosphites had been shown to be new environmental friendly chemical agents for plants. In this study, seven-year-old ‘Xiangling’ and ‘Xifu 4’ walnut trees were treated with different concentrations of potassium phosphite foliar fertilizer. The treatments were T1 (1500-fold dilution fluid of potassium phosphite), T2 (1000-fold dilution fluid of potassium phosphite) and CK (water). The results showed that the disease incidence rates of fruit treated with potassium phosphite were lower than CK. Moreover, the diseased fruit rates of ‘Xiangling’ (4) and ‘Xifu 4’ (14) in T2, lower than they (28 and 38) in CK. Metabolome and transcriptome further analysis revealed that potassium phosphite significantly increased the expression level of genes in the photosynthesis pathway and accumulated terpeniods, phenolic, salicylic acid and other secondary metabolic pathways. In addition, as salicylic acid content significantly increased, the expression level of the gene encoding the disease resistance-related protein (PR1) showed a corresponding trend. In vitro antibacterial tests of six related metabolites on C. gloeosporioides showed that hederagenin, 23-hydroxybetulinic acid, ursolic acid, eriodictyol, and salicylic acid had effect on C. gloeosporioides spores, among which salicylic acid and ursolic acid significantly inhibited the growth of C. gloeosporioides. Further experiments revealed that the minimum inhibitory concentrations of salicylic acid and ursolic acid were 2 and 5 g L−1, respectively. In addition, potassium phosphite could directly inhibit the growth of C. gloeosporioides spores in vitro tests. In conclusion, potassium phosphite enhanced walnut fruit disease resistance through up-regulated the genes related to photosynthetic performance and abundant in secondary metabolites, such as salicylic acid, terpenoids and phenolics, which were antibacterial effects on C. gloeosporioides.

A new approach for artificial pollination in walnut trees: AirPoll

Pollination is the first step in the plant's fruit development. Therefore, fruit setting does not occur without pollination. Some problems encountered in natural pollination cause pollination not to be achieved as desired and cause significant losses in yield and fruit quality. Artificial pollination applications with drones are the best way to solve these problems. In this study, the AirPoll artificial pollination machine, which performs artificial pollination through the air using drone technology, was developed and the operating success of the machine was tested in walnut gardens. In the experiment gardens, female flowers on 18 branches of 5 trees each in the artificially pollinated area with a drone and in the control area were marked with colored strings. Control trees were selected from a distance that would not be possible to transport pollen with a drone. As a result of the study carried out in 2020 and 2021, the average fruit setting rate in trees pollinated by drone was determined as 94.61%. In control trees, 32.33% fruit setting was achieved. Thus, it was determined that the productivity increase in artificial pollination with AirPoll was 62.28%. In addition, in the study, Computational Fluid Dynamics (CFD) simulation analysis was performed using ANSYS Fluent 2024 R1 software to predict the downward air flow and pollen distribution in the walnut tree crown. The analysis was carried out in 680 iterations using drone propellers at a rotation speed of 4500 rpm, 4 m/s airflow and a k-w viscous model. In the analysis, it was observed that the pollen was distributed homogeneously with the determined height and the created artificial pollination environment. Based on the results obtained from the simulations, a convergence criterion of 5e−3 for continuity and 1e−6 for speed, k, w was determined. Considering all the results, the ease of use of the developed AirPoll artificial pollination machine and the successful results obtained in field trials reveal the effectiveness of the AirPoll artificial pollination machine.

Extraction of phenolic compounds from Juglans regia L. leaves using aqueous solutions of eutectic solvents

The leaves of Juglans regia L. (walnut tree) are a rich source of bioactive phenolic compounds, particularly flavonoids and phenolic acids, which can be used in cosmetic applications due to their antioxidant properties. Conventionally, these compounds are extracted using volatile organic solvents. This study focuses on a more sustainable approach by designing a heat-assisted extraction process using aqueous solutions of eutectic solvents (ES) composed of cosmetic-compatible ingredients aiming for direct incorporation into cream formulations. In this context, aqueous solutions of the ES betaine + urea and betaine + 1,3-propanediol (PPD) were selected, considering their potential as cosmetic ingredients. The screening process targeted the maximum extraction yield of phenolic compounds (phenolic acids and flavonoids), quantified by HPLC-DAD. The selected variables were water content (25, 50 and 75 % in weight) and the molar proportion of the ES components. For comparison purposes, pure water was used as a reference solvent.The total phenolic content ranged between 5.5 and 14.6 mg/g of dry plant. Betaine:urea (2:1), betaine:PPD (1:2), betaine, and PPD, all with 50 % water mass percentage, were among those resulting in higher extraction yields and were further selected for bioactivity analysis. The system containing betaine presented the best antioxidant capacity, analysed through ferric reducing power, DPPH radical scavenging, and TBARS assays. The extracts obtained with PPD presented the highest antimicrobial activity against gram-positive and gram-negative bacteria, and yeast. The results show the potential of using binary aqueous mixtures of betaine, or 1,3-propanediol, which are simple ingredients in cosmetics formulations, to efficiently extract phenolic compounds from a natural matrix. Moreover, the bioactivity results, particularly in the antioxidant dimension, support using J. regia leaves as a source of natural antioxidants.

Phytochemical Analysis and Biological Activities of Different Extracts of Walnut (Juglans regia Linn.) Kernels

The walnut tree (Juglans regia Linn.) is a valuable medicinal plant. Almost all parts of this plant have significant nutritional and curative properties. The walnut fruit has been claimed to possess antioxidant, anti-inflammatory, anti-hypertensive, antimicrobial properties and high nutritional value. The present work is focused on the phytochemical screening and study of antioxidant and antimicrobial properties of Juglans regia kernels extracted from four different solvents; methanol, ethyl acetate, chloroform, and hexane. The highest yield of extract was obtained with methanol. The phytochemical screening showed the presence of alkaloids, flavonoids, tannins, phenolic compounds, glycosides, terpenoids, quinones, reducing sugars, and saponins in methanol extract. The total phenolic content was higher in methanolic extract. Methanolic and chloroform extracts possessed more flavonoid content than ethyl acetate and hexane extracts. The DPPH radical scavenging assay showed that the IC50 value of methanolic extract was 78.77 μg/mL with TPC 67.65 mg GAE/g and TFC 391.00 mg QE/g. The IC50 value obtained for ethyl acetate extract was 135.28 μg/mL with TPC 36.56 mg GAE/g and TFC 212.00 mg QE/g. The IC50 value for chloroform extract was 313.72 μg/mL with TPC 13.08 mg GAE/g and TFC 393.73 mg QE/g. The IC50 value of hexane extract was 898.99 μg/mL with TPC 6.26 mg GAE/g and TFC 77.82 mg QE/g. Only methanolic extract showed the antimicrobial activity against Proteus vulgaris, Pseudomonas aeruginosa, and Staphylococcus aureus.

Soil Fertility Dynamics and Identify the Most Limiting Nutrients Affecting Walnut Productivity in Nepal

This study aimed to assess the soil nutrient status in walnut orchards of different ages in Jajarkot district, Nepal, to understand soil fertility dynamics and identify the most limiting nutrients affecting walnut productivity. The research employed a randomized complete block design (RCBD) with three treatments representing different age groups of walnut orchards (1-5 years, 6-10 years, and 11-15 years), each replicated seven times across various municipalities. The study was conducted in Jajarkot district, Karnali Province, Nepal, encompassing municipalities including Nalgad, Junichadey, and Barekot, from March to April 2023. Soil samples were collected from multiple depths (1, 2, and 3 feet) in each orchard and analyzed for pH, soil organic matter (SOM), total nitrogen, available phosphorus, and available potassium. Data analysis included descriptive statistics, one-way analysis of variance (ANOVA), and correlation analyses to explore relationships between soil parameters and orchard age. The study showed that significant variations were observed among different age groups of walnut orchards for soil pH, SOM, nitrogen, phosphorus, and potassium levels. Soil pH decreased with orchard age, while SOM, nitrogen, and phosphorus tended to increase with orchard age. Phosphorus was identified as the most limiting nutrient across all sampled soils, followed by nitrogen and potassium. Moreover, strong correlations were found between orchard age and soil N (r = 0.894, p < 0.01) and P (r = 0.776, p < 0.01), underscoring age-dependent nutrient dynamics. The study highlights the critical role of orchard age in shaping soil nutrient dynamics in walnut orchards. Older orchards exhibited higher levels of SOM, nitrogen, and phosphorus, indicating the accumulation of organic matter and nutrients over time. Phosphorus emerged as the primary limiting nutrient, essential for root growth, flowering, and fruiting in walnut trees. These findings underscore the importance of targeted fertilization strategies to optimize soil fertility and sustain long-term walnut productivity in the region.

The effect of derum (bark of Juglans regia tree) extract on oral mucosa: An in vivo study based on epithelial atypia in rabbit model

Background and objectivesDerum, the bark of walnut tree (Juglans regia) has been used as a traditional tooth cleanser and chewed for its ability to bestow purple color to oral mucosa, tongue and lips Studies have shown that derum extract could affect oral epithelium after long term exposure, causing dysplasia. The aim of this in-vivo study was to evaluate the degree of epithelial dysplasia caused by varying durations and frequencies of topical derum application on oral mucosa of rabbits. Materials and MethodsFollowing ethical approval, derum extract was applied to the buccal vestibule of New Zealand white rabbits over three different periods (60 days, 120 days, 180 days) and two different protocols were used (daily application and once every 3 days). Accordingly, the animals were divided into four groups (A – daily derum application/B – derum applied once in 3 days/C – Positive control and acetone applied every alternate day/D – negative control), and three batches (I – 60 days/II – 120 days/III – 180 days). The animals were sacrificed, and oral biopsies prepared and examined under light microscope. The magnitude of epithelial changes was evaluated using epithelial atypia index (EAI) based on Smith and Pindborg histological grading system (1969) for epithelial dysplasia. ResultsMild dysplastic changes were detected in animals treated with derum extract regardless of the period of application. Similar results were noted among positive control group, and highest score was recorded in group A followed by group B with high tendency towards long-term derum application. Moderate changes were encountered only in group A that received derum for 180 days. Statistically, long-term derum application (180 days / Batch III in groups A and B), irrespective of the frequency of application, resulted in significantly higher mean EAI scores than all other groups or batches. ConclusionBased on this study, prolonged and frequent use of derum can induce dysplastic changes in rabbit oral mucosa, ranging from mild to moderate dysplasia. Further studies with extended times of exposure of derum to oral mucosa are recommended to document these adverse effects as an evidence base.

Impact of various heat sources on the transient heat transfer rate in a 3D cylinder consisting of parts with different thermal conductivity coefficients

Numerical analysis of time-dependent conductive heat transfer in three-dimensional solid bodies with a heat source is important in their use in various industries. In this article, an attempt has been made to investigate this issue for a cylinder consisting of four equal pieces with different thermal conductivity coefficients and heat sources, and conclusions have been drawn. The geometry of the cylinder consists of two lower (first) and upper (second) layers. In the lower layer of two solid bodies, one is a piece of rubber with a thermal conductivity coefficient of K1=0.16 w/m○k and the other is a piece of walnut wood with a thermal conductivity coefficient of K2=0.077 w/m○k and two solid objects are used in the upper layer. One is a piece of polyurethane with a thermal conductivity coefficient of K3=0.02 w/m○k and the other is a piece of cork with a thermal conductivity coefficient of K4=0.04 w/m○k. There are four heat source mechanisms: constant value, linear, quadratic, and sinusoidal or periodic heat source with a certain frequency. All the surfaces of the cylinder walls in the time interval 0 ≤ t ≤ 10 s10, T=0 are assumed. The obtained results show that the temperature distribution when the value of the heat source is constant affects a larger area, and the highest increase in temperature in the direction of the z-axis belongs to the constant, quadratic, sinusoidal and linear heat source, respectively.

Study on Soil Fertility Characteristics of Walnut Orchards with Different Parent Materials and Soil Types in Gyaca County, Tibet

Walnut trees on the Tibetan Plateau have sustainable and nutritious characteristics. They grow naturally without the use of any chemical fertilizers and pesticides. Therefore, the soil fertility of walnut orchards is a key factor influencing walnut yield and quality. This experiment measured and analyzed the basic soil nutrient content, microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), and leaf nutrient indicators in five types of representative walnut orchard soil parent materials in Gyaca County to clarify the fertility characteristics of different soil types and their correlations with walnut nutrients, providing a basis for the sustainable development of the plateau walnut industry. The results showed that there were significant differences in soil organic matter (SOM), total nitrogen (TN), available nutrient contents, and microbial activity among soil types with different parent materials. The comprehensive representation of available nutrient levels in the soils is as follows: gray-cinnamon soil and calcareous alluvial soil > mountain meadow soil > plateau prairie soil and brush prairie soil. The average MBC, MBN, and MBP contents in the five soils were 368.8 mg/kg, 28.4 mg/kg, and 23.6 mg/kg, respectively, and the content in the topsoil (0–20 cm) was higher than that of the subsoil (20–40 cm). The total nitrogen (PN), total phosphorus (PP), and total potassium (PK) contents in walnut leaves were found to be closely related to the soil physicochemical properties and microbial activity, among which five indicators, including soil TN, available nitrogen (AN), SOM, MBC, and slowly available potassium (SAK), had the greatest impact on leaf nutrient levels. These findings are valuable for the future management and development of walnut orchards. Therefore, for different soil parent materials and soil types, improving the soil fertility and actively applying nitrogen-rich organic fertilizers should be prioritized to improve the yield and quality of Tibetan Plateau walnuts.

Arbuscular mycorrhizal symbiosis with Rhizophagus irregularis DAOM197198 modifies the root transcriptome of walnut trees.

Walnut trees are cultivated and exploited worldwide for commercial timber and nut production. They are heterografted plants, with the rootstock selected to grow in different soil types and conditions and to provide the best anchorage, vigor, and resistance or tolerance to soil borne pests and diseases. However, no individual rootstock is tolerant of all factors that impact walnut production. In Europe, Juglans regia is mainly used as a rootstock. Like most terrestrial plants, walnut trees form arbuscular mycorrhizal symbioses, improving water and nutrient uptake and providing additional ecosystem services. Effects of arbuscular mycorrhizal symbiosis on root gene regulation, however, has never been assessed. We analyzed the response of one rootstock of J. regia to colonization by the arbuscular mycorrhizal fungus Rhizophagus irregularis DAOM197198. Plant growth as well as the nitrogen and phosphorus concentrations in roots and shoots were significantly increased in mycorrhizal plants versus non-colonized plants. In addition, we have shown that 1,549 genes were differentially expressed, with 832 and 717 genes up- and down-regulated, respectively. The analysis also revealed that some rootstock genes involved in plant nutrition through the mycorrhizal pathway, are regulated similarly as in other mycorrhizal woody species: Vitis vinifera and Populus trichocarpa. In addition, an enrichment analysis performed on GO and KEGG pathways revealed some regulation specific to J. regia (i.e., the juglone pathway). This analysis reinforces the role of arbuscular mycorrhizal symbiosis on root gene regulation and on the need to finely study the effects of diverse arbuscular mycorrhizal fungi on root gene regulation, but also of the scion on the functioning of an arbuscular mycorrhizal fungus in heterografted plants such as walnut tree.

Enhanced antimicrobial potency and stability of juglone/β-cyclodextrin inclusion complexes: a comparative study of formulation methods

Juglone (5-hydroxy-1,4-naphthoquinone), a natural antifungal and antibacterial agent derived from walnut trees, possesses significant therapeutic potential limited by its low water solubility and instability in varying pH and temperature conditions This study aims to address these limitations by enhancing juglone’s solubility, stability, and antimicrobial efficacy through the formation of inclusion complexes with β-cyclodextrin (β-CD). Employing methods such as co-precipitation, freeze-drying, and solvent evaporation, we synthesized these complexes and confirmed their formation using UV–vis, and FT-IR spectroscopy. The obtained optimum complex was characterized using SEM to reveal its structural properties, while NMR analysis showed significant chemical shift changes, indicative of complex formation between juglone and β-CD; additionally, XRD analysis confirmed the amorphous nature of the J-β-CD3-4 inclusion complex, providing direct evidence for its formation. Our findings reveal a notable enhancement in the pH and thermal stability of juglone within the β-CD inclusion complex, in comparison to its free form. Moreover, the antimicrobial activity of the juglone-β-CD complex surpassed that of juglone alone. The increased water solubility of juglone in the inclusion complex contributed to its enhanced antimicrobial activity. The inhibition zone diameters of J-β-CD3-4 inclusion complex against E. coli, S. aureus, and C. albicans were 7, 22, and 8.5 mm, respectively, relatively higher than juglone. Remarkably, in the broth microdluation method, the MIC and MBC values of the inclusion complex were determined to be much lower than those of free juglone, a significant fourfold decrease for S. aureus, and C. albicans and twofold for E. coli. These results underscore the potential of juglone-β-CD complexation in extending the applicability of juglone, especially in sectors such as food preservation, agriculture, and pharmaceuticals, where enhanced stability and efficacy of natural antimicrobial agents are crucial.