Almond Research Articles

Determining how almond (Prunus dulcis) harvest and processing contributes to low levels of glyphosate and glufosinate residues in almonds

AbstractCalifornia is the top producer of almonds [Prunus dulcis (Mill.) D.A. Webb] worldwide, generating more than $6 billion in revenue in 2020; the European Union (EU) is the primary importer of California almonds. Weed control in almond orchards is an important part of the preharvest process, because weeds can interfere with harvest equipment and host diseases. Glyphosate and glufosinate are broad-spectrum herbicides commonly used for preharvest weed control. Global differences in maximum residue limits (MRLs) and regulated compounds can pose a challenge for growers who rely on broad-spectrum herbicides such as glyphosate and glufosinate for preharvest weed control. The EU MRL for glyphosate and total glufosinate is currently 0.1 mg kg−1. The U.S. MRL for total glyphosate is 1 mg kg−1, and total glufosinate is 0.5 mg kg−1. An 8-wk field experiment, from spray to harvest, was conducted in an 8-ha commercial orchard to evaluate the potential contribution of the preharvest herbicide treatment to low levels of herbicide residue in almonds. Then, the same batch of almonds was followed through a commercial processing facility to evaluate the potential movement of herbicide residues from soil, debris, and hulls to almond kernels during processing. Glyphosate was not detected in any almond kernel samples at the end of processing. A glufosinate metabolite, 3-(methylphosphinico)propionic acid (MPP), was detected in kernels at the end of processing at about 0.1 mg kg−1, which is above the EU MRL for total glufosinate. Almonds sampled directly from the tree, without any contact with soil, were found to have elevated MPP residues. This indicates glufosinate or MPP translocation may be a factor in low-level glufosinate residues detected in almonds in some EU exports.

The combination of crop diversification and no tillage enhances key soil quality parameters related to soil functioning without compromising crop yields in a low-input rainfed almond orchard under semiarid Mediterranean conditions

Soils provide key ecosystem services and are crucial to combat climate change. Agriculture provides important ecosystem services but also causes negative environmental effects depending on agricultural management. In this regard, crop diversification is a promising sustainable land management strategy to combat soil erosion and degradation, mitigate climate change and ensure food security. Here, we assess the combined short-term effects of crop diversification and no tillage on several key soil physico-chemical parameters related to soil functioning as well as on crop yields in a rainfed almond (Prunus dulcis Mill.) orchard under semiarid Mediterranean conditions. Almond trees were inter-cropped with Capparis spinosa L. (caper) or Thymus hyemalis Lange (winter thyme) and compared with the almond monocrop system. The experimental design consisted of three plots in a randomized-block design, with three replicates for each crop management treatment (almond monocrop, almond inter-cropped with caper, and almond inter-cropped with winter thyme). Along with crop yields, the combined effects of crop diversification and no tillage on a range of soil quality and health indicators including soil physical (bulk density, aggregate stability, water retention and availability) and chemical (total and particulate organic carbon and nitrogen, ammonium and nitrate content, available macro- and micro-nutrients) properties were monitored in the topsoil and subsoil (at 0–10 and 10–30 cm depth, respectively) one and three years from establishment. Resultsfrom this study indicate that soil water retention capacity and water availability for plants were enhanced in both crop diversification systems after three years from their implementation at 0–30 cm depth. Likewise, improvements in particulate organic carbon and available N were observed in the subsoil of both crop diversifications. Crop diversification did not significantly affect the main crop yields, highlighting that crop diversification can be a promising sustainable management practice for improving soil health without compromising food security under semiarid Mediterranean conditions. Indeed, land equivalent ratios (LER) of almond trees inter-cropped with winter thyme were higher than those of their respective monocrop systems for two consecutive years, indicating that inter-cropping with aromatics can improve the productivity of rainfed woody monocrop systems under semiarid conditions. Our results emphasize the importance of selecting an appropriate secondary crop that ensures a permanent soil cover while contributes to enhance the agroecosystem productivity from the first year of establishment onwards to off-set plausible lower yields from the main crop. In this regard, preliminary assessments on soil condition and crop nutrient requirements are encouraged before designing and implementing a crop diversification in these low-input cropping systems.Likewise, long-term studies are needed to provide evidence on the stability of the production of diversified crop management, particularly in these low-input cropping systems under harsh environmental conditions.

Environmental Risk from Organic Residues

Soil nutrient imbalance is a global threat to food security and ecosystem sustainability but adding organic residues or constructing anthropogenic soils and technosols can optimize it. However, FAO considers organic residues not “risk-free”, mainly due to their heavy metal content. Despite the fact that applying pruning residues to soil is a worldwide fertilization practice, its potential heavy metal risk has been poorly studied. This work characterizes Cu, Zn, Cd, Cr, Ni and Pb elemental composition concentration and their solubility content in almond tree pruning, commercial peat substrate, hay straw, olive tree pruning, pomegranate peel, pine needle, date palm leaf pruning, sewage sludge compost and vine pruning. Furthermore, we compare the legal frameworks governing heavy metal content in agricultural substrates to heavy metal concentration in each residue. Results show that commercial peat substrate is the only one among those studied that surpasses the threshold value for Cr in agricultural substrates. All pruning residues met the heavy metal threshold value; hence, their application to soil involves minimal soil toxicity. Moreover, the solubility index of heavy metals and the maximum quantity of each residue are crucial to discerning a heavy metal-free organic fertilization plan.

Increasing Wood δ15N in Response to Pig Manure Application

Intensive livestock management impacts forest and trees in different ways. Pig manure is a major source of nitrogen (N) pollution of surface and ground waters in some European regions such as north-eastern Spain, but it is understudied how manure application impacts agroforestry systems. How pig manure affects tree radial growth and the N cycle was assessed by measuring N concentrations in soil, leaves and wood and δ15N in tree-ring wood in two tree species widely planted for agricultural (Prunus dulcis) and reforestation (Pinus halepensis) purposes in the study area. Soil physicochemical characteristics and the biomass and structure of major soil microbial groups were also measured. Trees irrigated with pig effluent (manure application) and control trees not subjected to manure application were compared. Soil N, phosphorus (P) and potassium (K) concentrations of fertilized trees increased, but soil microbiota biomass decreased. Similar growth between fertilized and non-fertilized pine trees was found, but lower growth in fertilized almond trees was observed. Leaf N concentrations decreased but δ15N wood increased in trees subjected to pig manure application. Pig manure application alters the N cycling in the soil and within trees.

Experimental Research on Unit Operation for Fruit Crops’ Bones Calibration

The article presents the results of the implementation of the mathematical planning of the experiment to determine the optimal parameters of the calibration process of cherry, sweet cherry, cherry plum, apricot and almond seeds. The essence of this process is the separation of seeds (bones) of fruit crops into fractions homogenous in size in order to highlight the middle fraction, which is about 80% of the total number of bones. The bones of the middle fraction are of the highest quality and are most suitable for sowing. The shape of the bones was evaluated by three parameters: length, width, and height. Calibration was performed according to the width of the bone. To carry out experimental studies, a calibration device was developed, the working body of which is the sieve part. Ball cleaners were used to prevent clogging of the perforated sieve. A mathematical theory of experimental planning was used. The criterion of optimization for all fruit crops was taken as an indicator of the quality of bone division into homogeneous fractions. The functional dependence of this indicator on the frequency and amplitude of oscillations of the grating part of the calibration unit, as well as on the angle of inclination of the sieves, was investigated. To implement the experimental data, we used a rotatable Boks plan of the second order. Regression models of the cherry, sweet cherry, cherry plum, apricot, and almond calibration process were obtained. Adequacy of the models was assessed by Fisher’s criterion. As a result, the optimal operating parameters of the installation were determined. This ensures the qualitative separation of the bones of fruit crops into homogeneous fractions with a mass deviation of up to 7%. An assessment of the quality of work of ball sieve cleaners was carried out. To do this, we used the coefficient of efficiency of the live cross-section. With the optimal parameters of the installation, the value of this coefficient of the unit for all fruit crops is within 0.87 to 0.95. This indicates that the calibration process is of high quality.

INTRODUCTORY SEARCH AND MOBILIZATION OF PRUNUS DULCIS (MILL.) D.A.WEBB SPECIMENS FOR RESEARCH IN KHOROL BOTANICAL GARDEN

The Khorol Botanical Garden is presented as a point of introduction of subtropical fruit plants, where Prunus dulcis (Mill.) D.A. Webb occupies a prominent place among the studied species, since the value of the stone core of this culture is widely known.
 Odesa, Zaporizhzhya and Cherkasy regions are shown as regions for the selection of introduction material, because in the last decade, thanks to the activities of the NGO «Ukrainian Walnut Association» and amateur gardeners, P. dulcis has become increasingly widespread.
 The expediency of selecting cultivars according to their description is substantiated, because the determining feature is the average and late flowering of plants, since in the conditions of the forest-steppe of Ukraine, early flowering ones can suffer from reverse frosts, which significantly affects the yield of the crop.
 The results of the search for P. dulcis for the mobilization of samples to the Khorol Botanical Garden are highlighted. It was established that in the steppe zone of Ukraine, a significant number of varieties of Ukrainian and foreign selection programs are cultivated, which bear fruit every year and form full seeds. The high adaptation of cultivars, their plasticity and winter resistance was shown, which made it possible to identify and mobilize samples of the following mid- and late-flowering varieties and forms: ‘Amaretto’, ‘Papershell’, ‘Vairo’, ‘Victoria’, ‘Dessertny’, ‘Meteor’, Pervenets Khramov’, ‘Foros’, ‘E5 Borozan’, ‘M 41 Alex’, ‘Ferragnès’, ‘Fentsia’, ‘Thin-skinned’, forms 9-A,1-D, 3-E, F–37 ‘Louise’ , F–58–12 ‘Paper’, № 1 (weeping), № 2, F–48.
 It is noted that the collected collection of P. dulcis samples will be further investigated for pollination with the establishment of differentiation between self-incompatible and self-compatible varieties and forms.
 It is emphasized that self-incompatible varieties, while producing viable pollen and ovules, are unable to fertilize the seed primordia of the same variety and, as a result, produce a harvest. Because of this, the presence of two or more varieties in a separate garden is necessary to ensure the transfer of pollen from the anthers of the flowers of one variety to the receptacles of the flowers of another. Insufficient pollination is a real loss of yield, so to ensure a good level of yield, the maximum number of flowers must be pollinated. In P. dulcis, the reduction in fruit number resulting from any pollination problem is rarely offset by the increase in fruit size and weight that occurs in other fruit crops.

THEORETICAL FOUNDATIONS OF FORMING A COLLECTION OF SUBTROPICAL FRUIT CROPS BASED ON THE AGROBIOSCIENCE STATION OF THE V.G. KOROLENKO POLTAVA NATIONAL PEDAGOGICAL UNIVERSITY

The results of studying the features and developing the establishment of a collection of subtropical fruit crops in open field conditions based on the agro-bioscience station of the V. G. Korolenko Poltava National Pedagogical University are presented. The theoretical foundations and recommendations regarding the peculiarities of wintering and collection formation in the conditions of a moderate climate of the forest-steppe of Ukraine are considered. A number of previously successfully introduced crops are identified, their species composition is characterized, and a series of factors that affect or may affect the further introduction process are established. 
 The idea of creating an introduction point with the formation of the main collection, which will include species such as Asimina triloba L., Zizyphus jujuba Mill., Punica granatum L., Ficus carica L., Diospyros virginiana L., Cydonia oblonga Mill., Prunus dulcis Mill., Mespilus germanica L., and Chaenomeles japonica Lindl., is put forward.

Host-microbiome metabolism of a plant toxin in bees.

While foraging for nectar and pollen, bees are exposed to a myriad of xenobiotics, including plant metabolites, which may exert a wide range of effects on their health. Although the bee genome encodes enzymes that help in the metabolism of xenobiotics, it has lower detoxification gene diversity than the genomes of other insects. Therefore, bees may rely on other components that shape their physiology, such as the microbiota, to degrade potentially toxic molecules. In this study, we show that amygdalin, a cyanogenic glycoside found in honey bee-pollinated almond trees, can be metabolized by both bees and members of the gut microbiota. In microbiota-deprived bees, amygdalin is degraded into prunasin, leading to prunasin accumulation in the midgut and hindgut. In microbiota-colonized bees, on the other hand, amygdalin is degraded even further, and prunasin does not accumulate in the gut, suggesting that the microbiota contribute to the full degradation of amygdalin into hydrogen cyanide. In vitro experiments demonstrated that amygdalin degradation by bee gut bacteria is strain-specific and not characteristic of a particular genus or species. We found strains of Bifidobacterium, Bombilactobacillus, and Gilliamella that can degrade amygdalin. The degradation mechanism appears to vary since only some strains produce prunasin as an intermediate. Finally, we investigated the basis of degradation in Bifidobacterium wkB204, a strain that fully degrades amygdalin. We found overexpression and secretion of several carbohydrate-degrading enzymes, including one in glycoside hydrolase family 3 (GH3). We expressed this GH3 in Escherichia coli and detected prunasin as a byproduct when cell lysates were cultured with amygdalin, supporting its contribution to amygdalin degradation. These findings demonstrate that both host and microbiota can act together to metabolize dietary plant metabolites.

Hurdles and clarifications for the cultivation of saffron in Jammu and Kashmir

Since saffron is a triploid crop, it does not generate seed when selfed or crossed and is passed down through the generations by daughter corms produced from the mother corms. As a result, agro-technology development is the only viable alternative for bringing this crop to its full potential. Saffron does not have any specific habitat preferences, as evidenced by discovering numerous previously unknown saffron farmed areas during the current study. The plant grows as a mixed crop under apple ( Malus domestica Borkh ), almond (Prunus amygdalus Batsch.), populus ( Populus alba L.), and walnut ( Juglans regia L.) trees, as well as in plains, undulated soils, hills, and rice fields. It can be found growing between 1585 and 2050 m above sea level. Different agro-techniques were standardized, among which compost soil (compost 250 gms per pot with 2 kgs of soil; 500 gms per tray with 4 kgs of soil; 10 kgs per bed) was found to be best for early flower production. Soil and farmyard manure (1:3), UDP 0.25 gms/pot (N-115.511+ K130.952+P-58.496 mg), soil DAP 650 mg/2 kg of soil (@P = 152.0899 mg), soil MOP 350 mg/2 kg (@ K = 183.37 mg) of soil was preeminent of procured in vitro raised cormlets in terms of their sprouting and survival of shoots. Corm density was also checked in the offseason of the crop, with growth activity of only saffron corms. Significant negative correlation was recorded with r = 0.82; n = 100; P ≤ 0.001. But the reverse trend was observed in the crop's growing season when most de-weeding and field preparations are accomplished. The study will benefit people in near future as it emphasized the imperative proofs and picture of saffron cultivation in Kashmir valley, reflects the realities of saffron cultivation and trounces the earlier myths. • Saffron is a triploid crop, hence fails to produce seed upon selfing or crossing. It is propagated by daughter corms produced from the mother corms. • Some unfamiliar saffron cultivated sites have also been located. • It grows along an altitudinal gradient of 1585–2050 m asl. i.e. from Nehama (1585 m) Budgam to Buzgow (2050 m)- Nilnag- Gogipathri. • Different agro-techniques were standardized and compost soil (Compost 250 gms per pot with 2 kgs of soil; 500 gms per tray with 4 kgs of soil; 10 kgs per bed) was found to be best with respect to early flower production. • Soil and farm yard manure 1:3, UDP 0.25 gms/pot (N-115.511+ K130.952+P-58.496 mg), soil DAP 650mg/2 kg of soil (@P = 152.0899 mg), soil MOP 350mg/2 kg (@ K = 183.37 mg) of soil was preeminent of procured invitro raised cormlets in terms of their sprouting and survival of shoots up to the second year of their growth period. • Knowledge of weed characteristics, morphology, ontogeny, nature of competition and degree of association with crops are pre-requisite for suggesting some efficient weed control measures. • The data on weeds revealed that most weed species belongs to three families with dominant family Asteraceae, followed by Brasicaceae, Fabaceace and Lamiaceae. • Corm density was checked in off season of the crop, with growth activity of only saffron corms, significant negative correlation was recorded with r = 0.82; n = 100; P ≤ 0.001. But reverse trend was observed in growth season of the crop when most de-weeding and field preparations are going on.

Leaf endophytic microbiomes of different almond cultivars grafted to the same rootstock.

We compared the bacterial endophytic communities of three genetically different almond cultivars that were all grafted on the same type of rootstock, growing side by side within a commercial orchard. We examined the diversity of leaf bacterial endophytes using cultivation-independent techniques and assessed the relative abundance of bacterial families. Two of these three cultivars were dominated by Pseudomonadaceae, while the bacterial composition of the third cultivar consisted mainly of Streptococcaceae. The experimental set up allowed us to analyse the impact of the shoot cultivar on endophytes, minimizing the influence of rootstock, biogeography, and cultivation status. Our data suggest that the shoot cultivar can shape the leaf endophytic community composition of almond trees. Our results suggest that the shoot cultivar controls the composition of the foliar bacterial endophytic community of almonds. Overall, our results could provide a first step to develop strategies for a more sustainable almond agriculture.

Amygdalin alleviated TGF-β-induced epithelial-mesenchymal transition in bronchial epithelial cells

ObjectiveTransforming growth factor-beta TGF-β-induced epithelial-mesenchymal transition (EMT) in bronchial epithelial cells contributes to airway wall remodeling in asthma. This study aims to explore the role of amygdalin, an active ingredient in bitter almonds, in TGF-β-induced EMT in bronchial epithelial cells and to elucidate the possible mechanisms underlying its biological effects. MethodsAn asthmatic mouse model was established through ovalbumin induction. Primary mouse bronchial epithelial cells and a human bronchial epithelial cell line were incubated with transforming growth factor-beta (TGF-β) to induce EMT, whose phenotype of cells was evaluated by the expressions of EMT markers [alpha-smooth muscle actin (α-SMA), vimentin, and fibronectin] and cell migration capacity. A co-immunoprecipitation assay was performed to assess the ubiquitination of heparanase (HPSE). ResultsIn asthmatic model mice, amygdalin treatment relieved airway wall remodeling and decreased expressions of EMT markers (α-SMA and vimentin). In TGF-β-treated bronchial epithelial cells, amygdalin treatment decreased the mRNA and protein levels of EMT markers (α-SMA, vimentin, and fibronectin) without impairing cell viability. Through the Swiss Target Prediction database, HPSE was screened as a candidate downstream target for amygdalin. HPSE overexpression further promoted TGF-β-induced EMT while the HPSE inhibitor suppressed TGF-β-induced EMT in bronchial epithelial cells. In addition, HPSE overexpression reversed the inhibitory effect of amygdalin on TGF-β-induced EMT in bronchial epithelial cells. The following mechanism exploration revealed that amygdalin downregulated HPSE expression by enhancing ubiquitination. ConclusionOur study showed that amygdalin inhibited TGF-β-induced EMT in bronchial epithelial cells and found that the anti-EMT activity of amygdalin might be related to its regulatory effect on HPSE expression.

Characterization of β-Tubulin Genes in Prunus persica and Prunus dulcis for Fingerprinting of their Interspecific Hybrids

Characterization of β-Tubulin Genes in Prunus persica and Prunus dulcis for Fingerprinting of their Interspecific Hybrids

Synthesis and characterization of a novel, pH-responsive sustained release nanocarrier using polyethylene glycol, graphene oxide, and natural silk fibroin protein by a green nano emulsification method to enhance cancer treatment

In this study, for the first time, by employing a simple and efficient double nano-emulsification method and using sweet almond oil as the organic phase, polyethylene glycol (PEG)/graphene oxide (GO)/silk fibroin (SF) hydrogel-nanocomposite was synthesized. The aim of the research was to fabricate a biocompatible targeted pH-sensitive sustained release carrier, improve the drug loading capacity and enhance the anticancer effect of doxorubicin (DOX) drug. The obtained values for the entrapment (%EE) and loading efficacy (%LE) were 87.75 ± 0.7 % and 46 ± 1 %, respectively, and these high values were due to the use of GO with a large specific surface area and the electrostatic interaction between the drug and SF. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the presence of all the components in the nanocomposite and the suitable interaction between them. Based on the results of dynamic light scattering analysis (DLS) and zeta potential analysis, the mean size of the carrier particles and its surface charge were 293.7 nm and −102.9 mV, respectively. The high negative charge was caused by the presence of hydroxyl groups in GO and SF and it caused proper stability of the nanocomposite. The spherical core-shell structure with its homogeneous surface was also observed in the field emission scanning electron microscopy (FE-SEM) image. The cumulative release percentage of the nanocarrier reached 95.75 after 96 h and it is higher in the acidic environment at all times. The results of fitting the release data to the kinetic models suggested that the mechanism of release was dissolution-controlled anomalous at pH 7.4 and diffusion-controlled anomalous at pH 5.4. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry showed an increase in toxicity on MCF-7 cells and improved apoptotic cell death compared to the free drug. Consequently, the findings of this research introduced and confirmed PEG/GO/SF nanocomposite as an attractive novel drug delivery system for pH-sensitive and sustained delivery of chemotherapeutic agents in biomedicine.

ПОСУХОСТІЙКІ ВИДИ ДЕРЕВ ТА КУЩІВ – ВАЖЛИВА ЛАНКА ДЛЯ ЗМЕНШЕННЯ НЕГАТИВНИХ ЕФЕКТІВ «МІСЬКИХ ОСТРОВІВ ТЕПЛА»

The water parameters of the leaves of 9 species of medium-sized trees (Aesculus pavia L., Aralia elata (Miq,) Seem., Broussonetia papyrifera (L.) L’Hér. ex Vent., Cercis canadensis L., Platycarya strobilacea Siebold & Zucc., Prunus dulcis (Mill.) D.A.Webb., Tetradium daniellii (Benn.) T.G. Hartley, Zizyphus jujuba Mill., Robinia viscosa Vent.) and 4 species of bushes (Cotinus coggygrya Scop., Cotinus coggygrya Scop. ‘Royal Purple’, Berberis vulgaris L. ‘Atropurpurea’, Corylus maxima Mill. ‘Atropurpurea’) were investigated in order to identify the most promising drought-tolerant ornamental species of woody plants from the temperate and continental climate zones, which are still not widely cultivated in the Polissia and Forest-Steppe zones of Ukraine. It will be a further recommendation to include them in the ecosystems of the urban environment to overcome the negative impact of the "urban heat island". In order to determine the relative drought resistance of plants, the following parameters of the water regime were measured: tissue hydration and water loss per unit of time.
 The test for drought resistance was carried out twice, when high temperatures are maintained: in early June (the leaves on trees and bushes are young), and also in early September (the leaves have already acquired all the features characteristic of their species). According to the results of the study, such medium-sized trees as: Aesculus pavia, Aralia elata, Cercis canadensis, Tetradium daniellii and Zizyphus jujube, as well as Cotinus coggygrya, Berberis vulgaris 'Atropurpurea' and Cotinus coggygrya 'Royal Purple' bushes can be recommended for urban landscaping as drought-resistant plants. Whereas, the tree species Broussonetia papurifera, Robinia viscosa, Prunus dulcis and Platycarya strobilacea, as well as the bushes Corylus maxima 'Atropurpurea' showed relatively lower drought resistance, which must be taken into account when landscaping, since, on the one hand, there is a need for additional watering, on the other hand in in one landscape exposure, it is appropriate to plant species with a similar level of drought resistance, which will facilitate further plant care. The slightly lower tolerance to drought of Corylus maxima 'Atropurpurea' may be due to the fact that only this species of the studied shrubs is shade-tolerant, while the other three species are light-loving plants, which must also be taken into account when creating plant compositions.

Biochemical Characterisation of Selected Edible Nut Seeds

The present study was focused to evaluate the phytochemical screening and biochemical estimation of ethanolic and aqueous extracts of edible nuts of Arachis hypogea, Anacardium occidentale, Prunus dulcis and Juglans regia. The phytochemical screening showed the presence of carbohydrate, protein, phenol and tannin, flavonoid, glycoside, steroid, alkaloid in all the studied nuts. The quantification of A. hypogeae, A. occidentale, P. dulcis and J. regia were performed to determine the total amount of carbohydrate, protein and phenol. The highest amount of Carbohydrate was present in A. occidentale (244.7 ± 6.3 mg GLC/g), The Protein content was highly present in J. regia (455.14 ± 3.7 mg BSA/g) and the highest amount of Phenol was present in P. dulcis (355.78 ± 7.2 mg GAE/g).

Highly carbonized Prunus dulcis shell-derived activated carbon for high-performance supercapacitor applications

Highly carbonized Prunus dulcis shell-derived activated carbon for high-performance supercapacitor applications

Disease management during bloom affects the floral microbiome but not pollination in a mass‐flowering crop

Abstract Flowering crops are heavily managed during bloom to both promote pollination and prevent disease. Disease management practices can alter the floral microbiome, including pathogens and nontarget microbes. However, whether agrochemical presence or altered microbiome composition affect pollinator foraging and pollination services is unclear. We assessed effects of orchard management tactics and landscape context on the flower microbiome in almond, Prunus dulcis. Fourteen orchards (five conventional, four organic and five conventional with habitat augmentation) were sampled at early and peak bloom to characterize bacterial and fungal communities associated with floral tissues. The surveys were complemented by an artificial flower experiment to assess effects of fungicides and microbes on honey bee foraging. Finally, a field trial was conducted to test effects of fungicides and microbes on pollination. As bloom progressed, bacterial and fungal abundance and diversity increased across all floral tissue types and management strategies. The magnitude by which microbial abundance and diversity were affected varied, with proximity to apiaries and orchard management having notable effects on bacteria and fungi respectively. Experiments revealed that fungicides reduced nectar removal by honey bees; however, neither fungicide nor microbe treatments affected pollination, as measured through pollen tube initiation and growth. Synthesis and applications. Our results reveal that microbiota associated with flowers of a pollinator‐dependent crop are temporally dynamic and sensitive to management practices. However, pollination services in almond may be resilient to both agrochemical disturbance and microbial augmentation of flowers, the latter of which may become more prominent as microbial solutions to disease management are embraced in agroecosystems.

Temporal susceptibility of almond pruning wounds to infection by fungal canker pathogens in California

AbstractNumerous fungal canker pathogens threaten almond production in California, causing high tree mortality and reducing orchard longevity. Pruning wounds are the main infection sites for these pathogens. This study aimed to identify the lowest risk period for pruning almond trees and to determine the duration of susceptibility of pruning wounds to fungal infections. During 2 years at two locations, pruning wounds were made monthly from September to January and inoculated with Botryosphaeria dothidea, Eutypa lata, Neofusicoccum parvum or Neoscytalidium dimidiatum, at 0, 1, 2, 3, 5 and 8 weeks after pruning. Pruning wounds were susceptible to infection by N. parvum and N. dimidiatum from September to December, with a significant decrease in susceptibility for wounds made in January relative to September. Fresh wounds had the highest probability of infection by N. dimidiatum, as wounds 1 week or older were less likely to be infected. Pruning month did not significantly impact wound susceptibility to B. dothidea; susceptibility decreased sharply with wound age. Wound susceptibility to E. lata significantly differed amongst pruning months, with pruning wounds of 1 week or older made in December and January being the least susceptible. These results indicated that delayed pruning in December and January can reduce the risks of canker pathogen infections compared to early pruning from September to November. This study showed that pruning wounds were most susceptible to infection during the first 2 weeks following pruning; thus, pruning wounds should be protected for at least 2 weeks shortly after pruning.

Pentapeptide-Zinc Chelate from Sweet Almond Expeller Amandin Hydrolysates: Structural and Physicochemical Characteristics, Stability and Zinc Transport Ability In Vitro.

To promote the application of almond expellers, sweet almond expeller globulin (amandin) was extracted for the preparation of bioactive peptides. After dual enzymatic hydrolysis, Sephadex G-15 gel isolation, reverse-phase high-performance liquid chromatography purification and ESI-MS/MS analysis, two novel peptides Val-Asp-Leu-Val-Ala-Glu-Val-Pro-Arg-Gly-Leu (1164.45 Da) and Leu-Asp-Arg-Leu-Glu (644.77 Da) were identified in sweet almond expeller amandin hydrolysates. Leu-Asp-Arg-Leu-Glu (LDRLE) of excellent zinc-chelating capacity (24.73 mg/g) was selected for preparation of peptide-zinc chelate. Structural analysis revealed that zinc ions were mainly bonded to amino group and carboxyl group of LDRLE. Potential toxicity and some physicochemical properties of LDRLE and Val-Asp-Leu-Val-Ala-Glu-Val-Pro-Arg-Gly-Leu (VDLVAEVPRGL) were predicted in silico. The results demonstrated that both LDRLE and VDLVAEVPRGL were not toxic. Additionally, zinc solubility of LDRLE-zinc chelate was much higher than that of zinc sulphate and zinc gluconate at pH 6.0-10.0 and against gastrointestinal digestion at 37 °C (p < 0.05). However, incubation at 100 °C for 20-60 min significantly reduced zinc-solubility of LDRLE-zinc chelate. Moreover, the chelate showed higher zinc transport ability in vitro than zinc sulphate and zinc gluconate (p < 0.05). Therefore, peptides isolated from sweet almond expeller amandin have potential applications as ingredient of zinc supplements.

Effect of relative humidity on the quality and safety of peeled almond kernels (Prunus dulcis Mill.) during simulated maritime transport/storage.

Long-term transport and storage of peeled almonds under unsuitable conditions may cause the product's rejection. To get knowledge in this topic, peeled almonds were stored at 25°C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268nm (K268 ) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (<80%) for maritime transport and long-term storage of almond kernels. PRACTICAL APPLICATION: High levels of relative humidity during storage/transport of almond kernels favor fungal growth, mycotoxin production, and secondary oxidation (rancidity). It is recommended to keep the almond kernels under low RH(<80%) in maritime transport and long storage, especially in tropical countries.