Search Results (59)

Brown spot, caused by Alternaria alternata, is the most important leaf fungal disease threatening kiwifruit production in China, and it is typically controlled through the application of fungicides, such as procymidone and difenoconazole. To date, fungicide resistance development has not yet been systematically reported for the pathogen of kiwifruit. A total of 135 single-conidium A. alternata isolates were collected from different cities in Zhejiang Province, China. Alternaria alternata developed prevailing resistance to procymidone and initial resistance to difenoconazole, with resistance frequencies of 60.7 and 13.3%, respectively. Positive cross-resistance was observed between procymidone and iprodione but not between procymidone and difenoconazole, tebuconazole, prochloraz, pydiflumetofen, pyraclostrobin, or thiophanate-methyl. Moreover, no cross-resistance was observed between difenoconazole and all other tested fungicides, including the two other demethylation inhibitors, tebuconazole and prochloraz. A fitness penalty was not detected in procymidone-resistant (Pro^R) or difenoconazole-resistant (Dif^R) isolates. However, double-resistant (Pro^R Dif^R) isolates had a fitness penalty, showing significantly decreased sporulation, germination, and pathogenicity. The P894L single point mutation, caused by the change from CCA to CTA at the 894th codon of Os1, was detected in Pro^R isolates. Molecular dynamic simulation showed that the P894L mutation significantly decreased the inhibitory activity of procymidone against AaOs1 in A. alternata. These results provide insight into the development and characteristics of fungicide resistance, offering guidance for the study and management of kiwifruit diseases. Full article

Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are powerful techniques that have been employed to analyze foodstuffs comprehensively. These techniques offer in-depth information about the chemical composition, structure, and spatial distribution of components in a variety of food products. Quantitative NMR is widely applied for precise quantification of metabolites, authentication of food products, and monitoring of food quality. Low-field ¹H-NMR relaxometry is an important technique for investigating the most abundant components of intact foodstuffs based on relaxation times and amplitude of the NMR signals. In particular, information on water compartments, diffusion, and movement can be obtained by detecting proton signals because of H₂O in foodstuffs. Saffron adulterations with calendula, safflower, turmeric, sandalwood, and tartrazine have been analyzed using benchtop NMR, an alternative to the high-field NMR approach. The fraudulent addition of Robusta to Arabica coffee was investigated by ¹H-NMR Spectroscopy and the marker of Robusta coffee can be detected in the ¹H-NMR spectrum. MRI images can be a reliable tool for appreciating morphological differences in vegetables and fruits. In kiwifruit, the effects of water loss and the states of water were investigated using MRI. It provides informative images regarding the spin density distribution of water molecules and the relationship between water and cellular tissues. ¹H-NMR spectra of aqueous extract of kiwifruits affected by elephantiasis show a higher number of small oligosaccharides than healthy fruits do. One of the frauds that has been detected in the olive oil sector reflects the addition of hazelnut oils to olive oils. However, using the NMR methodology, it is possible to distinguish the two types of oils, since, in hazelnut oils, linolenic fatty chains and squalene are absent, which is also indicated by the ¹H-NMR spectrum. NMR has been applied to detect milk adulterations, such as bovine milk being spiked with known levels of whey, urea, synthetic urine, and synthetic milk. In particular, T2 relaxation time has been found to be significantly affected by adulteration as it increases with adulterant percentage. The ¹H spectrum of honey samples from two botanical species shows the presence of signals due to the specific markers of two botanical species. NMR generates large datasets due to the complexity of food matrices and, to deal with this, chemometrics (multivariate analysis) can be applied to monitor the changes in the constituents of foodstuffs, assess the self-life, and determine the effects of storage conditions. Multivariate analysis could help in managing and interpreting complex NMR data by reducing dimensionality and identifying patterns. NMR spectroscopy followed by multivariate analysis can be channelized for evaluating the nutritional profile of food products by quantifying vitamins, sugars, fatty acids, amino acids, and other nutrients. In this review, we summarize the importance of NMR spectroscopy in chemical profiling and quality assessment of food products employing magnetic resonance technologies and multivariate statistical analysis. Full article

Background: The Actinidia deliciosa cultivar ‘Guichang’ is a remarkable kiwifruit variety. The phenotypic traits of this variety are influenced by the climatic conditions in Guizhou. The flowering time, which is shaped by multiple environmental factors, has a substantial impact on both the fruit yield and quality. Objectives and Methods: This study was designed to explore the molecular mechanisms underlying the transition from bud to flowering in ‘Guichang’ through transcriptomic and proteomic analyses. Results: The transcriptomic results revealed that 6201 genes were up-regulated, while 5849 genes were down-regulated during this transition. Key genes related to hormone signaling, such as AdPIF4, AdBSK, AdBRI1, and AdCYCD3, were recognized as crucial regulators. The proteomic analysis detected a total of 10,488 proteins. Among them, AdBSK1 was regulated, while AdPIF4, AdBRI1, and AdCYCD3 showed stable expressions. A moderate positive correlation (with a Pearson correlation coefficient of 0.445) was found between the expression levels of transcriptomics and proteomics. When AdBSK1 was over-expressed in Arabidopsis, it promoted earlier flowering. This was achieved by down-regulating FLC and up-regulating FT and SOC1. Conclusions: This study clarifies the molecular mechanisms involved in the bud-to-flowering transition in ‘Guichang’. It emphasizes the intricate interactions among hormonal pathways, key genes, and proteins, which are consistent with the broader understanding of plant flowering regulation in recent research. These findings are significant for deepening our understanding of, and potentially controlling, the flowering mechanisms. Full article

Kiwifruits are highly valued for their nutritional and health-related benefits as well as for their economic importance, since they significantly contribute to the economy of many countries that cultivate them. However, kiwifruits are very sensitive to diseases that may substantially impact their final quantity and quality. Computer vision (CV) has been extensively employed for disease recognition in the agricultural sector within the last decade; yet there are limited works dealing with kiwifruit disease recognition, and there is an obvious lack of open datasets to promote relevant research, especially when compared to research on other cultivations, e.g., grapes. To this end, this study introduces the first-reported open dataset for kiwifruit leaf disease recognition, including Alternaria, Nematodes and Phytophthora, while image datasets of Nematodes have not been previously reported. The proposed dataset, named AgriVision-Kiwi Dataset, has been used first for leaf detection with You Only Look Once version 11 (YOLOv11), reporting a bounding box loss of 0.053, and then to train various deep learning models for kiwifruit diseases recognition, reporting accuracies of 98.80% ± 0.5, e.g., 98.30% to 99.30%, after 10-fold cross-validation. The introduced dataset aims to encourage the development of CV applications towards the timely prevention of diseases’ spreading. Full article

A syndrome called “Kiwifruit Decline Syndrome” (KiDS) affects kiwifruit in several Mediterranean areas, causing growth arrest and wilt that rapidly progress to desiccation, scarce root growth, absence of fibrous roots, brown soft-rotting areas, and cortical detachment from the central cylinder. The origin is considered multifactorial, and a correlation with hydraulic conductance impairment caused by a high vapor pressure deficit (VPD) and temperature was detected. In this work, over-tree micro-sprinkler irrigation and shading nets were tested to protect leaves from overheating and locally decrease VPD. Leaf gas exchanges, leaf temperature, stem water potential, stem growth, root starch content, root xylem vessel diameter, density, and vulnerability to cavitation were assessed. A positive effect of over-tree irrigation associated with shading was observed: lower leaf temperature, higher stem water potential, stomatal conductance, and photosynthesis were detected; moreover, root starch content was higher in the summer. Narrow xylem vessel diameters were observed, indicating a long-term adaptation to rising VPD for lower vulnerability to cavitation, in all plants, but higher diameter, lower density, and higher vulnerability index indicated lower plant water stress under over-tree irrigation associated with shading. These results indicate that microclimate control by proper agronomic management can protect kiwifruit from climate stress, decreasing the risk of KiDS onset. Full article

Kiwifruit is widely recognized for its rich nutritional composition and potential health benefits, yet comparative studies on different cultivars remain limited. In this study, we investigated the physicochemical properties, free sugar and organic acid content, and bioactive compounds in four kiwifruit cultivars: Hayward (HW), Halla Gold (HG), Jecy Gold (JG), and Sweet Gold (SG). This study aimed to determine variations in the composition of these cultivars and assess their antioxidant potential. The pH did not significantly differ among the kiwifruit cultivars. Sweetness and acidity are key sensory attributes in fruit, and SG exhibited the highest acidity, soluble solid content, and reducing sugar content. Accordingly, SG had the highest free sugar (11.25 g/100 mL) and organic acid (13.08 g/100 mL) levels. Phenolic acid (473.01 μg/mL) and flavonol (96.43 μg/mL) contents were most abundant in SG. In this cultivar, chlorogenic acid and epigallocatechin levels were the highest, while epicatechin and naringenin were detected only in SG. Finally, antioxidant activities (i.e., DPPH, ABTS, and hydroxyl radical scavenging activities and FRAP) were highest in SG, followed by HG, JG, and HW. The SG cultivar used in this study exhibits strong antioxidant activity, disease-suppressing effects, skin protection properties, and the potential to reduce the risk of chronic diseases due to its high phenolic compound content. These findings suggest that SG, which possesses excellent taste and functional properties, may serve as a promising candidate for the development of high-quality kiwifruit-based products. Full article

Pseudomonas syringae pv. actinidiae (Psa) is responsible for causing kiwifruit canker disease. The detection of Psa is commonly carried out using normal PCR and culture-based isolation. However, normal PCR does not differentiate between live and dead cells, potentially resulting in the incorrect estimation of the amount of infectious substance in a sample. Such an incorrect estimation could result in unnecessary phytosanitary strategies and control measures. This study attempts to establish a specific assay for detecting only live Psa bacterial cells. To achieve this, a pair of strain-specific primers designed from HopZ3 effector were used, and the traditional PCR method was assessed using a nucleic acid-binding dye (propidium monoazide—PMA), establishing a PMA–PCR system and conditions for detecting live Psa in this study. Sensitivity tests showed a detection limit of 10 cfu/mL and 1 pg/μL. This method was also tested in diseased kiwifruit tissues and can be seen as a rapid and dependable replacement to PCR methods for detecting only those infective kiwifruit materials with viable Psa. Full article

This work evaluated red kiwifruit plants’ spray treatment with cis-3-hexenyl butyrate (HB) as an inductor of some metabolic mechanisms related to fruit ripening, including an increase in anthocyanin content and the red hue color parameter. Considering their key role as ripening parameters for postharvest fruit quality and sorting assessment, the soluble solid content (SSC) and the flesh firmness penetrometer (FFP) were also measured. Treated plants received an application of 50 mM HB, administered exactly 2 and 4 weeks before the commercial harvest. At harvest time and during postharvest fruit ripening, near-infrared (NIR) spectral acquisitions were performed in order to check the feasibility of a rapid and non-destructive prediction of fruit anthocyanin content and SSC, coupled to destructive measurements and chemometric modelling. Regarding technological and chemical results, HB treatment indicates an optimum overall qualitative storage at 30 days. The fruit from treated plants is characterized by good quality parameters, including higher SSC, enhanced red hue (a* value) and increased anthocyanin content, despite similar weight loss to the untreated fruit. The obtained chemometric results underscore the promise and feasibility of NIRs in terms of detecting and estimating anthocyanin content and SSC in red kiwifruit, in order to pursue an evident perspective of improvement. Full article

Colchicine and ⁶⁰Co-γ radiation are commonly used breeding techniques for kiwifruit, offering advantages such as low cost, rapid execution, and high efficiency. The buds of red-fleshed kiwifruit (Actinidia chinensis) cv. ‘Donghong’ were used as experimental material and subjected to different concentrations of colchicine and different doses of ⁶⁰Co-γ radiation, respectively. Then, the buds were grafted on rootstock, and the ploidy, leaf size, and fruit quality of mutant fruit were evaluated, and principal component analysis (PCA) and simple sequence repeat markers were used to comprehensively assess and detect genetic variations, respectively. The results indicated that a total of 19 buds successfully germinated, with 13 branches successfully bearing fruit. Significant changes were observed in both leaf and fruit morphology following the mutation treatments. Most of the mutant materials showed significant increases in fruit weight, flesh firmness, and soluble sugar content, while titratable acidity and ascorbic acid content significantly decreased. Notably, the 25Gy ⁶⁰Co-γ radiation (25d) treatment demonstrated outstanding results, with fruit weight increasing by 256.10%, soluble sugar content rising by 88.29%, titratable acidity decreasing by 29.86%, and ascorbic acid content increasing by 35.60%. PCA results showed that the 25d mutant had the best comprehensive traits. And, except for the 0.4c mutant, all other mutant materials exhibited significant genetic changes at the DNA level. Full article

Automated kiwi harvesting hinges on the seamless deployment of a detection model and the accurate detection of kiwifruits. However, practical challenges, such as the limited computational resources on harvesting robots and occlusions among fruits, hinder the effectiveness of automated picking. To address these issues, this paper introduces EDT-YOLOv8n, a lightweight and efficient network architecture based on YOLOv8n. The proposed model integrates the Effective Mobile Inverted Bottleneck Convolution (EMBC) module to replace the C2f modules, mitigating the channel information loss and bolstering generalization. Additionally, the DySample upsampler, an ultra-lightweight and effective dynamic upsampler, improves feature extraction and resource efficiency when compared to traditional nearest-neighbor upsampling. Furthermore, a novel Task Align Dynamic Detection Head (TADDH) is implemented, incorporating group normalization for a more efficient convolutional structure and optimizing the alignment between the classification and localization tasks. The experimental results reveal that the proposed EDT-YOLOv8n model achieves higher precision (86.1%), mAP0.5 (91.5%), and mAP0.5-0.95 (65.9%), while reducing the number of parameters, the number of floating-point operations, and the model size by 15.5%, 12.4%, and 15.0%, respectively. These improvements demonstrate the model’s effectiveness and efficiency in supporting kiwifruit localization and automated harvesting tasks. Full article

Kiwifruit, as a climacteric fruit, undergoes rapid ripening and senescence after harvest, making it highly susceptible to softening, rotting, and spoilage. Therefore, monitoring the key quality parameters of kiwifruit, particularly the accurate detection of soluble solids content (SSC), is considered crucial. The performance of two spectral acquisition methods—diffuse reflectance and diffuse transmission—in detecting SSC in kiwifruit was compared. Various preprocessing methods and feature wavelength selection techniques were employed, and regression models were constructed using partial least squares (PLS) analysis. The stability and accuracy of the models were validated through an independent validation set. The results indicated that the spectral data acquired by the diffuse reflectance method, preprocessed using Savitzky–Golay smoothing and combined with competitive adaptive reweighted sampling (CARS), yielded a coefficient of determination (R²) of 0.98 for the prediction set, with a root-mean-square error (RMSE) of 0.66. In contrast, the spectral data obtained by the diffuse transmission method, preprocessed using multiplicative scatter correction and combined with CARS, achieved an R² of 0.95 and an RMSE of 0.93 for the prediction set. This study demonstrated that both methods were effective for detecting SSC in kiwifruit, with the diffuse reflectance method showing the greater advantage. Full article

Actinidia chlorotic ringspot-associated virus (AcCRaV, Emaravirus actinidiae) is prevalent in Chinese kiwifruit, leading to substantial yield reduction. The intricate nature of symptoms presents diagnostic challenges, underscoring the necessity for a rapid and accurate detection method that facilitates effective control. In this investigation, AcCRaV isolates from key kiwi-producing regions in Sichuan province were collected and analyzed, with representative strains chosen as experimental materials. Primers targeting the nucleoprotein gene of AcCRaV were designed, and their codon usage was optimized to enhance performance. Various serological methods utilizing polyclonal antibodies were developed, including ELISA, dot immunobinding assay, and AcCRaV-specific gold immunochromatographic bands (AcCRaV-GICS). Field samples exhibited high specificity and sensitivity when tested using these methods. Furthermore, the results obtained from a large number of field samples are consistent with those derived from RT-PCR analysis, further validating the applicability of our approach. A detection method capable of handling a large volume of field samples infected with AcCRaV is currently lacking; thus, our system construction provides an important reference for addressing this gap. Full article

The commercial value of kiwifruit is determined mostly by its nutritional composition and antioxidant content. The enrichment of these traits in an era where climate change affects kiwi growth conditions is worth investigating via the application of biostimulants that enhance plant growth. In this work, we evaluated the effects of three commercial biostimulants on the metabolism and growth characteristics of the Actinidia deliciosa cultivar ‘Hayward’: (I) a humic and fulvic-based biostimulant, (II) a glycine–betaine–proline-based biostimulant, and (III) a vegetal amino acid-based biostimulant. A biostimulant-free treatment was used as a control. In the two-year experiment (2022 and 2023), the growth characteristics of kiwi trees were measured, such as stem length, the number of leaves, leaf area, and fresh and dry biomass at the end of each growing season. The leaves’ total chlorophyll, total phenolics, and proline content were detected during the two seasons in order to obtain more insights into plant metabolism. Κiwifruit qualities and antioxidant traits, such as total soluble solids, titratable acidity, firmness, fresh and dry biomass, DPPH, and ascorbic acid (vitamin C), were recorded during the postharvest life for each season. Data analysis illustrated the beneficial impact of some biostimulants on several of the previously mentioned parameters, such as antioxidant kiwifruit traits, especially in the case of glycine–betaine–proline-based acid-based biostimulants. Full article

There is a growing interest in various types of kiwifruits, such as the “yellow” kiwifruit (Actinidia chinensis var. chinensis) and the “baby” kiwifruit of Actinidia arguta. These fruits are rich in bioactive compounds, which contribute to their nutraceutical properties, but they nevertheless have a shorter shelf life, resulting in economic losses. This study aims to chemically characterize kiwifruit juices from SunGold and baby kiwifruit varieties (Hortgem Rua and Hortgem Tahi) to improve knowledge and explore the suitability of these products for producing low-alcohol beverages using non-Saccharomyces strains, with the purpose of reducing waste and generating value-added processing. Total soluble solids, acidity, hardness, dry matter, total phenolic content, and antioxidant capacity were used as indicators of fruit quality. Chemical characterization of fresh kiwifruit juices revealed distinct profiles among varieties, with SunGold juice exhibiting higher sugar content and acidity. Citric acid was the predominant organic acid, while, as expected, tartaric was not detected. Kiwifruit juice fermentations by T. delbrueckii UMY196 were always completed regardless of the type of juice used, producing beverages with ethanol content ranging from 6.46 to 8.85% (v/v). The analysis of volatile organic compounds highlighted the presence of several molecules, contributing to aroma profiles with relevant differences among the three kiwifruit-based drinks. In particular, the total concentration of esters in the beverages reached 8.2 mg/L, 9.2 mg/L, and 8.6 mg/L in the Tahi, Rua, and SunGold beverages, respectively. The qualitative and quantitative profiles of the kiwifruit drinks revealed a pronounced perception of acidity and fruity traits, with significant differences observed by Principal Component Analysis (PCA) in aroma descriptors among the proposed beverages. The possibility of using unsold, overripe, or waste fruits to prepare new products with an increase in the sustainability of this supply chain is set. Full article

Kiwifruit (Actinidia spp.) is a perennial fruit tree, and the fruit of kiwifruit is economically and nutritionally important worldwide. To date, approximately 23 species of kiwifruit viruses have been reported worldwide. As for the detection method for kiwifruit viruses, previous reports mostly used the single RT-PCR detection method. In the detection of kiwifruit viruses, multiplex RT-PCR has the advantages of being fast, reliable and inexpensive. In this study, a stable, efficient and reliable multiplex RT-PCR method for the detection of the five most common kiwifruit viruses was established. The concentrations of Mg²⁺ and HS-Taq and the annealing temperature in the multiplex PCR system were optimized. The results indicate that the optimal annealing temperature was 56 °C; the optimal concentration of added Mg²⁺ was 2 mM; and the optimal concentration of HS-Taq was 1.0 U/μL. The stability of the optimized multiplex RT-PCR system was verified by field sample testing, and the results showed that the multiplex RT-PCR system was stable, efficient and reliable. This will provide much convenience for the detection of kiwifruit viruses in the future. Full article