Nut bush pesticide limits: urgent need for a comprehensive strategy to address current and emerging insect pests and insecticide options in the Australian macadamia industry
In Australia, macadamia orchards are attacked by four main insect pest groups. Management and control of three of these key pests currently relies on broad-spectrum insecticides whose long-term future is questionable. Of the 23 insecticides registered for use in macadamia in Australia, 19 face issues affecting their availability and 12 are presently not approved in the EU, the USA or Canada. These international markets may refuse produce that does not adhere to their own insecticide use standards, hence Australian produce may be excluded from market access. Many of the potential replacement integrated pest management methods of pest control are generally considered less effective by the industry and have not been adopted. There are 17 insect pest groups identified by the industry, any of which have potential to become major problems if broad-spectrum insecticide options become unavailable. Thirteen pest groups need urgent attention as they are at risk of losing current effective control methods, and no replacement solutions have yet been developed. The lag period for research and development to identify new chemical and biological control solutions means there is now an urgent need for the macadamia industry to craft a strategy for sustainable pest management for each pest. Critically, this industry strategy needs to address the vulnerabilities identified in this paper, identify potential solutions for any cases of market failure and consider funding mechanisms to address these gaps. On economic and sustainability grounds, potential biological control options should be explored, especially in cases where insecticide control options are vulnerable.
https://doi.org/10.1002/ps.8043
Quality evaluation of fresh pistachios (Pistacia vera L.) cultivars coated with chitosan/TiO2 nanocomposite
Fresh pistachios are rich in dietary fiber, minerals and unsaturated fatty acids, but they have a short shelf life. This investigation examined the effect of pre-harvest foliar application with chitosan (500 and 1000 mg. L-1), nano-chitosan (250 and 500 mg. L-1), and chitosan/TiO2 nanocomposite (250 and 500 mg. L-1) coating films on the postharvest physiology and storage of fresh pistachios (Pistacia vera cvs. Akbari and Ahmad Aghaei) cultivar during storage at 4 ± 0.5 °C. It was found that, fresh pistachios' shelf life could by increased by up to 30 days by the use of chitosan/TiO2 nanocomposite coating for foliar application. The decay index of the composite coated fruits was 4-6 % lower than that of the control group, and after 50-60 days the bacterial contamination appeared in cultivars; respectively. The nanocomposite treatments reduced the fruits weight between 30 and 40 %, which was 15 % higher that of than uncoated fruits. The pre-harvest application of chitosan/TiO2 coating reduced microbial contamination, weight loss, phenylalanine ammonialyase (PAL) activity and saturated fatty acids, and increased unsaturated fatty acids, antioxidant properties, sensory properties, essential minerals, superoxide dismutase (SOD), quality indicators and shelf life. These results demonstrated that the chitosan/TiO2 (250 and 500 mg. L-1) coating film effectively preserved the nutrient composition, sensory quality, nutritional value, antioxidant capacity and shelf life of fresh pistachio.
https://doi.org/10.1016/j.ijbiomac.2023.129055
Variation in pigments in pecan testa during kernel development and storage
The pecan (Carya illinoinensis) is an important tree nut worldwide. Browning of the testa during storage considerably reduces its quality. However, the pigments that cause browning and their accumulation patterns are poorly understood. We analyzed the color changes in the testa during the five developmental stages of the kernel after storage at room temperature to compare differences in their color and identify the pigments. Samples exhibiting different colors along with their corresponding -80 °C storage samples were selected for metabolomic analysis. A total of 591 phenolic compounds were detected, 52 phenolics showed regulatory effects on testa discoloration, and 59 metabolites were identified as possible precursors of the pigments. This study revealed the most thorough phenolic composition of pecan to date. Further, the findings provide new insights into the mechanisms of testa browning, deepens our understanding of the bioactive value of pecans, and contributes to the breeding of less browning-susceptible varieties.
https://doi.org/10.1016/j.foodchem.2023.137989
Fe2O3/carbon derived from peanut shell hybrid as an advanced anode for high performance lithium ion batteries
Carbon materials derived from biomass behave sustainability, easy availability, low cost and environmentally benign. And Fe2O3 are considered as promising anodes for high-performance Li-ion batteries (LIBs) because of their rich electrochemical properties, higher theoretical capacity (1007 mAh g−1), non-toxicity, high corrosion resistance and safety. However, the high irreversible capacity loss and poor cycling stability of Fe2O3 hinders its commercial applications in LIBs. In this work, we have developed a Fe2O3@C derived from peanut shell composite by two-step hydrothermal method and low-temperature calcination with the assistance of Fe(NO3)3. As an anode for LIBs, the Fe2O3@C composite an excellent electrochemical performance in term of the specific capacity of 1000.8 mAh g−1 at 200 mA g−1 after 100 cycles, and high rate capability of 573.5 mAh g−1 even at 1 A g−1 after 200 cycles. This enhancement could be attributed to the porous carbon matrix combined with Fe2O3 nanoparticles which could increase contact area between electrolyte and active materials, improve conductivity, and accommodate the volume variations via additional void space during cycling. This work may be provide a new approach to improve anode materials using carbon derived-from biomass with larger reversible capacity and long cycle life in LIBs.
https://doi.org/10.1016/j.est.2023.107731
Effect of drought stress and subsequent re-watering on the physiology and nutrition of Pistacia vera and Pistacia atlantica
Arid and semi-arid regions are characterised by extreme conditions including drought stress and salinity. These factors profoundly affect the agricultural sector. The objective of this work is to study the effect of drought and re-watering on leaf gas exchange, chlorophyll fluorescence and mineral nutrition in Pistacia vera and Pistacia atlantica. Water stress was applied to individuals of P. vera and P. atlantica for 23days, followed by rehydration for 7days. The results showed a clear reduction in water relations, leaf gas exchange and chlorophyll content in P. vera. Compared to P. vera, P. atlantica maintained less affected water status, total chlorophyll content, leaf gas exchange and chlorophyll fluorescence, stable Zn and Fe proportion, and even elevated K and Cu. The changes in the chlorophyll fluorescence parameter were manifested particularly at the maximal fluorescence (Fm). In contrast, no change was recorded at the minimal fluorescence (F0). After re-hydration, although water status was fully recovered in both species, stomatal conductance (gs), net photosynthesis (A) and transpiration rate (E) remain with lower values than the well-watered seedlings. P. atlantica was better adapted to drought stress than P. vera.
https://doi.org/10.1071/FP23097TKTK
Effect of deficit irrigation on physiological, morphological and fruit quality traits of six walnut tree cultivars in the inland area of Central Asia
Persian walnut, a drought-sensitive tree, exhibits significant genetic variation in functional traits in response to drought—a domain that remains largely unexplored. This study examines the impact of two distinct irrigation regimes—conventional irrigation (CI) and deficit irrigation (DI)—on physiological, morphological, and fruit quality traits across six walnut tree cultivars in a scion orchard during the summer drought period. Our findings revealed significant effects of irrigation treatments on soil water content, with notable drought stress observed in Win 185, Xinjufeng, and Zha71 under DI. Win 185 and Xinfeng, subjected to DI, exhibited diminished photosynthetic rates (A) and stomatal conductance (gs), whereas Win 185, Xinjufeng, Xinxin 2, and Zha71 displayed heightened instantaneous water use efficiency (WUEi) under DI. The maximum photochemical efficiency of photosystem II (Fv/Fm) and chlorophyll index were also affected in Win 185, Xinfeng, Xinjufeng, Xinxin 2 and Zha71 subjected to the DI treatment. Identified as primary drought response strategies, stomatal regulation, osmotic adjustment, and morphological adaptations varied uniquely among cultivars, potentially mitigating the adverse effects of drought on fruit quality. Notably, DI induced minor changes in fruit quality for Win 185, Xinlu, and Zha71, resulting in varying reductions in fruit diameter and weight. This suggests the possibility of achieving reduced water consumption while preserving fruit quality in specific cultivars. Phenotypic plasticity was evident across all traits; however, its response to drought exhibited cultivar-specific variations. A nuanced understanding of phenotypic plasticity's role in fruit quality is essential for optimizing deficit irrigation practices across diverse walnut cultivars.
https://doi.org/10.1016/j.scienta.2024.112951
Yield prediction in a peanut breeding program using remote sensing data and machine learning algorithms
Peanut is a critical food crop worldwide, and the development of high-throughput phenotyping techniques is essential for enhancing the crop’s genetic gain rate. Given the obvious challenges of directly estimating peanut yields through remote sensing, an approach that utilizes above-ground phenotypes to estimate underground yield is necessary. To that end, this study leveraged unmanned aerial vehicles (UAVs) for high-throughput phenotyping of surface traits in peanut. Using a diverse set of peanut germplasm planted in 2021 and 2022, UAV flight missions were repeatedly conducted to capture image data that were used to construct high-resolution multitemporal sigmoidal growth curves based on apparent characteristics, such as canopy cover and canopy height. Latent phenotypes extracted from these growth curves and their first derivatives informed the development of advanced machine learning models, specifically random forest and eXtreme Gradient Boosting (XGBoost), to estimate yield in the peanut plots. The random forest model exhibited exceptional predictive accuracy (R2 = 0.93), while XGBoost was also reasonably effective (R2 = 0.88). When using confusion matrices to evaluate the classification abilities of each model, the two models proved valuable in a breeding pipeline, particularly for filtering out underperforming genotypes. In addition, the random forest model excelled in identifying top-performing material while minimizing Type I and Type II errors. Overall, these findings underscore the potential of machine learning models, especially random forests and XGBoost, in predicting peanut yield and improving the efficiency of peanut breeding programs.
https://doi.org/10.3389/fpls.2024.1339864
What's in my Pot? Six Colletotrichum Species Causing Anthracnose in Brazilian Pecan Orchards
Pecan (Carya illinoinensis) is one important exotic forest crop cultivated in South America, specifically in Brazil, Uruguay, and Argentina. However, diseases such as anthracnose, favored by high humidity conditions and high summer temperatures, make its cultivation difficult, causing important loss to pecan farmers. This study used morphological and molecular approaches to identify the Colletotrichum species causing anthracnose in pecan plantations in Southern Brazil. The isolates obtained from pecan fruits with anthracnose symptoms were grouped through quantitative morphological characteristics into three distinct morphotypes. Molecular analysis of nuclear genes allowed the identification of six species of Colletotrichum causing anthracnose in pecan: C. nymphaeae, C. fioriniae, C. gloeosporioides, C. siamense, C. kahawae, and C. karsti. Three of these species are reported for the first time as causal agents of anthracnose in pecan. Therefore, these results provide an important basis for the adoption and/or development of anthracnose management strategies in pecan orchards cultivated in southern Brazil and neighboring countries.
https://doi.org/10.1007/s00284-024-03622-y
A haplotype-resolved chromosome-level assembly and annotation of European hazelnut (C. avellana cv. Jefferson) provides insight into mechanisms of eastern filbert blight resistance
European hazelnut (Corylus avellana L.) is an important tree nut crop. Hazelnut production in North America is currently limited in scalability due to Anisogramma anomala, a fungal pathogen that causes Eastern Filbert Blight (EFB) disease in hazelnut. Successful deployment of EFB resistant cultivars has been limited to the state of Oregon, where the breeding program at Oregon State University (OSU) has released cultivars with a dominant allele at a single resistance locus identified by classical breeding, linkage mapping, and molecular markers. 'Jefferson' is resistant to the predominant EFB biotype in Oregon and has been selected by the OSU breeding program as a model for hazelnut genetic and genomic research. Here, we present a near complete, haplotype-resolved chromosome-level hazelnut genome assembly for C. avellana 'Jefferson'. This new assembly is a significant improvement over a previously published genome draft. Analysis of genomic regions linked to EFB resistance and self-incompatibility confirmed haplotype splitting and identified new gene candidates that are essential for downstream molecular marker development, thereby facilitating breeding efforts.
https://doi.org/10.1093/g3journal/jkae021
Comparative metabolomics analysis reveals secondary cell wall thickening as a barrier to resist Aspergillus flavus infection in groundnut
Aflatoxin contamination caused by Aspergillus flavus significantly threatens food safety and human health. Resistance to aflatoxin is a highly complex and quantitative trait, but the underlying molecular and biochemical mechanisms are poorly understood. The present study aims to identify the resistance-related metabolites in groundnut that influence the defense mechanism against aflatoxin. Here, metabolite profiling of resistant (55–437) and susceptible (TMV-2) groundnut genotypes, which exhibited contrasting levels of resistance to A. flavus growth and aflatoxin accumulation under pathogen- or mock-inoculated treatments, was undertaken using liquid chromatography and high-resolution mass spectrometry (LC-HRMS). Non-targeted metabolomic analysis revealed key resistance-related metabolites belonging to phenylpropanoids, flavonoids, fatty acids, alkaloids, and terpenoid biosynthetic pathways. The phenylpropanoids - hydroxycinnamic acid amides (HCAAs) and lignins were among the most abundantly accumulated metabolites in the resistant genotype compared to the susceptible genotype. HCAAs and lignins are deposited as polymers and conjugated metabolites to strengthen the secondary cell wall, which acts as a barrier to pathogen entry. Further, histochemical staining confirmed the secondary cell wall thickening due to HCAAs and lignin depositions. Quantitative real-time PCR studies revealed higher expressions of phenylalanine ammonia-lyase (PAL), 4-coumarate: CoA ligase (4CL), cinnamoyl CoA reductase (CCR2), cinnamoyl alcohol dehydrogenase (CAD1), agmatine hydroxycinnamoyl transferase (ACT), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR) and flavonol synthase (FLS) in the pathogen-inoculated resistant genotype than in the susceptible genotype. This study reveals that the resistance to aflatoxin contamination in groundnut genotypes is associated with secondary cell wall thickening due to the deposition of HCAAs and lignins.
https://doi.org/10.1056/NEJMoa2312382