Kiwifruit Production Research Articles

Comparative analysis of phenolic compounds in different thinned unripe kiwifruits and their biological functions

Thinned unripe kiwifruits (TUK) are considered the major agro by-products in kiwifruit production. To promote their potential applications, polyphenols and biological effects of unripe fruits from nine commercial kiwifruit cultivars were compared. Our findings showed that TUK were rich in bioactive polyphenols, which varied greatly by different cultivars. Indeed, catechin, epicatechin, procyanidin PB1, procyanidin B2, protocatechuic acid, neochlorogenic acid, and gallic acid were measured as the major phenolic components in most TUK, with the highest levels observed in ‘Hongao’ and ‘Cuiyu’ cultivars. Furthermore, TUK exerted strong in vitro antioxidant capacities, inhibitory effects on digestive enzymes, and anti-inflammatory activities. Particularly, their stronger antioxidant effects and inhibitory effects on digestive enzymes were probably attributed to their higher contents of phenolic compounds, especially procyanidin B2. Collectively, our findings reveal that TUK are potential resources of valuable polyphenols, which can be exploited as natural antioxidants and natural inhibitors of α-glucosidase and α-amylase.

Armillaria Species Causing Kiwifruit Vine Decline and Root Rot in Northeastern Türkiye: A Growing Concern for Kiwifruit Health

ABSTRACTKiwifruit (Actinidia deliciosa) production in northeastern Türkiye is facing an emerging threat from Armillaria root rot. Surveys conducted in August 2021 and 2022 revealed that 10.5%–17.5% of the 200–500 vines within each of 35 kiwifruit orchards in the Perşembe, Gülyalı and Altınordu districts of Ordu province exhibited symptoms of Armillaria root rot, including complete defoliation. Diseased plants exhibited diagnostic signs on their root collars and woody roots, including white mycelial fans, extensive wood rot and rhizomorphs. A single Armillaria isolate was obtained from each of the 35 symptomatic orchards. Molecular identification, employing DNA sequencing of the large subunit (LSU) region of rDNA, the translation elongation factor subunit 1‐alpha (TEF1) gene and the second largest RNA polymerase II B‐subunit (RPB2) gene, identified 20 isolates as Armillaria gallica and 15 as A. mellea. Phylogenetic analyses, based on TEF1 alignments, further supported the species identification with a 100% bootstrap value. To examine genetic diversity, start codon targeted (SCoT) marker 13 was used, successfully differentiating the two Armillaria species and revealing three distinct clades. Clades I and II comprised 15 and 5 isolates of A. gallica, respectively, while Clade III contained all 15 A. mellea isolates. Pathogenicity testing on kiwifruit seedlings (cv. Hayward) revealed the ability of both A. gallica and A. mellea isolates to induce disease. Rhizomorph‐producing isolates in kiwifruit seedlings displayed high virulence, inducing severe leaf necrosis and seedling mortality, while isolates lacking these structures were non‐pathogenic. This study identifies the first global instance of A. gallica causing kiwifruit root rot. This finding, along with the identification of A. mellea as a causal agent in the country, highlights the emerging threat of Armillaria root rot to kiwifruit production in the region.

Climate Change Impacts on and Response Strategies for Kiwifruit Production: A Comprehensive Review.

Climate change, a pressing global concern, poses significant challenges to agricultural systems worldwide. Among the myriad impacts of climate change, the cultivation of kiwifruit trees (Actinidia spp.) faces multifaceted challenges. In this review, we delve into the intricate effects of climate change on kiwifruit production, which span phenological shifts, distributional changes, physiological responses, and ecological interactions. Understanding these complexities is crucial for devising effective adaptation and mitigation strategies to safeguard kiwifruit production amidst climate variability. This review scrutinizes the influence of rising global temperatures, altered precipitation patterns, and a heightened frequency of extreme weather events on the regions where kiwifruits are cultivated. Additionally, it delves into the ramifications of changing climatic conditions on kiwifruit tree physiology, phenology, and susceptibility to pests and diseases. The economic and social repercussions of climate change on kiwifruit production, including yield losses, livelihood impacts, and market dynamics, are thoroughly examined. In response to these challenges, this review proposes tailored adaptation and mitigation strategies for kiwifruit cultivation. This includes breeding climate-resilient kiwifruit cultivars of the Actinidia species that could withstand drought and high temperatures. Additional measures would involve implementing sustainable farming practices like irrigation, mulching, rain shelters, and shade management, as well as conserving soil and water resources. Through an examination of the literature, this review showcases the existing innovative approaches for climate change adaptation in kiwifruit farming. It concludes with recommendations for future research directions aimed at promoting the sustainability and resilience of fruit production, particularly in the context of kiwifruit cultivation, amid a changing climate.

Integrated analyses of the plant and soil microbiome identify Phytopythium vexans as agent of the Kiwifruit Vine Decline Syndrome

Abstract Background and aims The Kiwifruit Vine Decline Syndrome (KVDS) is a disease that is currently a challenge for kiwifruit production in Italy, and it is spreading in new production areas. However, the causal agent of this syndrome has not been clearly identified, and we still know little about the overall effects of KVDS on the interactions between the host plant and its microbiome. Methods In this study, we combined metabarcoding and targeted isolation (leaf baiting) to characterize the changes in the rhizosphere and root microbiomes associated with symptoms of KVDS. Results Our results suggest that KVDS has little impact on the bacterial, fungal, and oomycete communities associated with soil and roots, and we detected weak signatures of potential dysbiosis. On the other hand, we found a consistent association of the oomycete Phytopythium vexans with samples from plants symptomatic to KVDS, which matches the nucleotide sequences of the isolates obtained through baiting and, partially, the isolates from previous studies. Conclusion While our results support the idea that P. vexans might be the major candidate agent of KVDS, there are still several unanswered questions that need to be addressed before being able to provide effective solutions to this emerging challenge in kiwifruit production.

Genome sequencing and CAZymes repertoire analysis of Diaporthe eres P3-1W causing postharvest fruit rot of 'Hongyang' kiwifruit in China.

Postharvest rot caused by various fungal pathogens is a damaging disease affecting kiwifruit production and quality, resulting in significant annual economic losses. This study focused on isolating the strain P3-1W, identified as Diaporthe eres, as the causal agent of 'Hongyang' postharvest rot disease in China. The investigation highlighted cell wall degrading enzymes (CWDEs) as crucial pathogenic factors. Specially, the enzymatic activities of cellulase, β-galactosidase, polygalacturonase, and pectin methylesterases peaked significantly on the second day after infection of D. eres P3-1W. To gain a comprehensive understanding of these CWDEs, the genome of this strain was sequenced using PacBio and Illumina sequencing technologies. The analysis revealed that the genome of D. eres P3-1W spans 58,489,835 bp, with an N50 of 5,939,879 bp and a GC content of 50.7%. A total of 15,407 total protein-coding genes (PCGs) were predicted and functionally annotated. Notably, 857 carbohydrate-active enzymes (CAZymes) were identified in D. eres P3-1W, with 521 CWDEs consisting of 374 glycoside hydrolases (GHs), 108 carbohydrate esterase (CEs) and 91 polysaccharide lyases (PLs). Additionally, 221 auxiliary activities (AAs), 91 glycosyltransferases (GTs), and 108 carbohydrate binding modules (CBMs) were detected. These findings offer valuable insights into the CAZymes of D. eres P3-1W.

Pseudomonas syringae pv. actinidiae Unique Effector HopZ5 Interacts with GF14C to Trigger Plant Immunity.

The bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is the most devastating disease threatening the global kiwifruit production. This pathogen delivers multiple effector proteins into plant cells to resist plant immune responses and facilitate their survival. Here, we focused on the unique effector HopZ5 in Psa, which previously has been reported to have virulence functions. In this study, our results showed that HopZ5 could cause macroscopic cell death and trigger a serious immune response by agroinfiltration in Nicotiana benthamiana, along with upregulated expression of immunity-related genes and significant accumulation of reactive oxygen species and callose. Subsequently, we confirmed that HopZ5 interacted with the phosphoserine-binding protein GF14C in both the nonhost plant N. benthamiana (NbGF14C) and the host plant kiwifruit (AcGF14C), and silencing of NbGF14C compromised HopZ5-mediated cell death, suggesting that GF14C plays a crucial role in the detection of HopZ5. Further studies showed that overexpression of NbGF14C both markedly reduced the infection of Sclerotinia sclerotiorum and Phytophthora capsica in N. benthamiana, and overexpression of AcGF14C significantly enhanced the resistance of kiwifruit against Psa, indicating that GF14C positively regulates plant immunity. Collectively, our results revealed that the virulence effector HopZ5 could be recognized by plants and interact with GF14C to activate plant immunity.

No tillage and organic fertilization improved kiwifruit productivity through shifting soil properties and microbiome

AbstractThe preservation of edaphic quality and productivity is critical for the ecological sustainability of vine orchards. The heavy utilization of intensified tillage and singular chemical fertilizers can shift changes in edaphic physicochemical and biological features, thus exerting significant pressure on agroecosystems. In current research, we assessed the shifts in soil physicochemical features and soil microbiome composition over 11 years carrying out no tillage and organic fertilizer substitution in a typical Chinese Guanzhong kiwifruit production area, and explore the fundamental factors that contribute to alterations in the microbial community and the influence on kiwifruit performance. Results showed that long‐term no tillage and organic fertilizer improved the soil condition by significantly increasing the proportion of soil macroaggregates, bulk density, and nutrient content (e.g., organic matter, nitrogen, and ammonia), as compared to conventional tillage with chemical fertilization. Moreover, no tillage significantly increased soil bacterial α‐diversity but had no significant effects on fungal. No tillage also enhanced the abundance of potential beneficial soil bacteria (e.g., Acidobacteria, Actinobacteria, and Nitrospira), while decreasing the abundance of Proteobacteria, Pseudomonas, and Fusarium. In addition, no tillage and mixed fertilized soil microbial network exhibited higher complexity (i.e., node and edge numbers, and positive edge proportion) and connectivity (i.e., average number of neighbors) than conventional tillage and chemical fertilization group. Changes in nitrate, ammonia, available phosphorus, and pH values accounted for the variation in the structure of soil microbial community. Hence, the utilization of both no tillage and organic fertilization practices could serve as a suitable and sustainable approach for managing kiwifruit production in the fragile environmental conditions of the Chinese Guanzhong region, and lead to an improvement in soil nutrient levels and help regulate the soil microbial community.

Comparison of Aroma and Taste Profiles of Kiwi Wine Fermented with/without Peel by Combining Intelligent Sensory, Gas Chromatography-Mass Spectrometry, and Proton Nuclear Magnetic Resonance.

Kiwi wine (KW) is tipically made by fermenting juice from peeled kiwifruit, resulting in the disposal of peel and pomace as by-products. However, the peel contains various beneficial compounds, like phenols and flavonoids. Since the peel is edible and rich in these compounds, incorporating it into the fermentation process of KW presents a potential solution to minimize by-product waste. This study compared the aroma and taste profiles of KW from peeled (PKW) and unpeeled (UKW) kiwifruits by combining intelligent sensory technology, GC-MS, and 1H-NMR. Focusing on aroma profiles, 75 volatile organic compounds (VOCs) were identified in KW fermented with peel, and 73 VOCs in KW without peel, with 62 VOCs common to both. Among these compounds, rose oxide, D-citronellol, and bornylene were more abundant in UKW, while hexyl acetate, isoamyl acetate, and 2,4,5-trichlorobenzene were significantly higher in PKW. For taste profiles, E-tongue analysis revealed differences in the taste profiles of KW from the two sources. A total of 74 molecules were characterized using 1H-NMR. UKW exhibited significantly higher levels of tartrate, galactarate, N-acetylserotonin, 4-hydroxy-3-methoxymandelate, fumarate, and N-acetylglycine, along with a significantly lower level of oxypurinol compared to PKW. This study seeks to develop the theoretical understanding of the fermentation of kiwifruit with peel in sight of the utilization of the whole fruit for KW production, to increase the economic value of kiwifruit production.

Management of Root-Knot Nematode (Meloidogyne spp.) on Kiwifruit Seedlings using Different Plant Extracts, Biocontrol Agents, and Chemical Nematicides

Root-knot nematodes (RKN), (Meloidogyne spp.), are the major biotic factor responsible for the limiting production of Kiwifruit in Nepal including Kiwifruit orchard of Warm Temperate Horticulture Center, Nepal. Hence, there is a pressing demand for nematicides that are both easily accessible and cost-effective while being environmentally friendly. A screenhouse experiment was conducted in the Summer of 2023 with an objective to evaluate the effects of different plant extracts, bio-control agents, and chemical nematicides against RKN on Kiwifruit seedlings. The experiment was set up in a Completely Randomized Design with three replications and eight treatments which include the extracts of Allium sativum and Lantana camara, Trichoderma viride, Pseudomonas fluorescens, Cartap hydrochloride, Fosthiazate, Inoculated control and Uninoculated control. The results revealed that Trichoderma viride proved to be the most effective in reducing the nematode population, displaying a low root gall index of 3.11, a minimal reproductive factor of 0.24, and a high percentage of nematode control at 91.71%. It was also found to be efficient in promoting the growth parameters of Kiwifruit seedlings. Additionally, regression analysis exhibited a significantly positive interaction between root gall index and reproductive factor, while indicating a negative interaction between reproductive factor and growth parameters. Therefore, T. viride (@ 20 gm per 2000 cm3 of soil) should be soil drenched before the seedlings are transplanted into the main field for effective and sustainable management of RKN. Nevertheless, further research is needed to determine the efficacy of T. viride in infested roots of Kiwifruit trees in field condition of Kiwifruit orchard.

E3 Ubiquitin Ligase PUB23 in Kiwifruit Interacts with Trihelix Transcription Factor GT1 and Negatively Regulates Immune Responses against Pseudomonas syringae pv. actinidiae.

Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) is the most serious disease threatening kiwifruit production. Our previous study found genes encoding the U-box containing proteins were significantly regulated by Psa infection. Here, we report a U-box type E3 ubiquitin ligase PUB23 in kiwifruit which acts as a negative regulator of immune responses against Psa. PUB23 was found to physically interact with GT1, a trihelix transcription factor, in vitro and in vivo. The expression of GT1 was up-regulated in PUB23-silenced plants, indicating that interacting with PUB23 may directly or indirectly suppress GT1 expression. The silencing of PUB23 led to enhanced immune responses of PAMP-triggered immunity (PTI), including a higher expression level of defense marker genes PR1 and RIN4, and increased accumulation of hydrogen peroxide and superoxide anion. Our results reveal a negative role PUB23 plays in kiwifruit immune responses against Psa and may regulate gene expression by interacting with GT1.

Organizational support, market access, and farmers' adoption of agricultural green production technology: evidence from the main kiwifruit production areas in Shaanxi Province.

Industrial organizations play a crucial role in transforming the production and management practices of smallholder farmers, encouraging the adoption of environmentally friendly production methods. However, limited studies have conducted comprehensive research examining how these industrial organizations effectively encourage farmers to adopt green production technologies. To address this research gap, this study examines the influence of organizational support on the adoption of agricultural green production technologies among 645 kiwifruit farmers in Shaanxi Province, northwestern China, using cross-sectional survey data from 2022. In addition, this research explores the mechanisms and heterogeneity in this impact. In our analysis, we estimated Probit models and mediation effect models, which show a positive influence of organizational support on farmers' adoption of these technologies. Notably, both institutional support and tool support have a more pronounced positive effect on this adoption. The mechanism analysis shows that organizational support facilitates farmers' adoption of these agricultural green production technologies by expanding their access to high-value markets. Furthermore, when considering heterogeneity among farmers, the study finds that organizational support has the most significant impact on the adoption of these technologies among farmers operating at a moderate scale. Moreover, our research highlights a technology linkage effect in the adoption process. Specifically, organizational support has a positive and significant effect on the adoption of technologies like bagging, physical control, and soil testing formulas, while also having a positive but statistically insignificant impact on technologies such as pollution-free pesticides and organic fertilizer substitution. In conclusion, the study proposes to increase assistance to industrial organizations, to play an influential role in guiding and driving farmers.

Two transcription factors, AcREM14 and AcC3H1, enhance the resistance of kiwifruit Actinidiachinensis var. chinensis to Pseudomonas syringae pv. actinidiae.

Kiwifruit bacterial canker is a global disease caused by Pseudomonas syringae pv. actinidiae (Psa), which poses a major threat to kiwifruit production worldwide. Despite the economic importance of Actinidia chinensis var. chinensis, only a few resistant varieties have been identified to date. In this study, we screened 44 kiwifruit F1 hybrid lines derived from a cross between two A. chinensis var. chinensis lines and identified two offspring with distinct resistance to Psa: resistant offspring RH12 and susceptible offspring SH14. To identify traits associated with resistance, we performed a comparative transcriptomic analysis of these two lines. We identified several highly differentially expressed genes (DEGs) associated with flavonoid synthesis, pathogen interactions, and hormone signaling pathways, which play essential roles in disease resistance. Additionally, using weighted gene co-expression network analysis, we identified six core transcription factors. Moreover, qRT-PCR results demonstrated the high expression of AcC3H1 and AcREM14 in Psa-induced highly resistant hybrid lines. Ultimately, Overexpression of AcC3H1 and AcREM14 in kiwifruit enhanced disease resistance, and this was associated with upregulation of enzymatic activity and gene expression in the salicylic acid (SA) signaling pathway. Our study elucidates a molecular mechanism underlying disease resistance in kiwifruit and contributes to the advancement of research on kiwifruit breeding.

Update on the global prevalence and severity of kiwifruit allergy: a scoping review

SummaryThe production and use of kiwifruit, and their derived products, has seen rapid growth in the food industry with some 4 467 099 tonnes produced in 2021. A key area of development has been the increased use of kiwifruit waste streams to support sustainable food production systems. However, kiwifruit is emerging as a common elicitor of food allergy worldwide. Therefore, the present research focuses on summarising the current literature on kiwifruit‐induced human food allergy. Of the available information, a total of 7098 titles were found and 107 articles were included in the current study following full‐text screening. Most research concentrated on the prevalence of allergenicity and was performed within Europe, North America, Asia, Africa, South America and Oceania. Food allergy to kiwifruit ranged from oral allergy syndrome to anaphylaxis in humans. Few studies considered the need for labelling or public education. Given the increased usage of kiwifruit across a range of food streams, further research is required due to the greater focus on utilisation of these products in the food industry.

Impact of social networks on fertilizer use efficiency in China: Evidence from kiwifruit production in Shaanxi province.

Improving fertilizer use efficiency (FUE) is an effective way to reduce the fertilizer use and non-point source pollution in agriculture production in China. Existing research related to fertilizer use efficiency ignores the impact of famers' social networks, which can significantly affect the fertilizer use and its efficiency. This paper analyzed the impact of social networks on fertilizer use efficiency and the mediator effect of green fertilization technology adoption, based on the calculation of fertilizer use efficiency of 569 kiwifruit farmers in Shaanxi province of China surveyed in 2021 by using stochastic frontier method. The results show that the FUE of kiwifruit production ranged within 0.1027-0.9945, with an average value of 0.333, which showed great variability, and fertilizer input had an average 66.7% reduction potential without reducing output. Social networks and its four dimensions all had a significant positive impact on FUE, in which network trust and network learning had a greater impact on FUE. Farmers' adoption of green fertilization technology played a positive mediator effect in the process of social networks influencing their fertilizer use efficiency, which was mainly promoted by network trust and learning. Farmers' experience in agricultural production, joining the cooperative, the quantity of village agricultural supply points had a significant positive impact on fertilizer use efficiency, while age and gentle of the head of household had a significant negative impact of fertilizer use efficiency. Planting scale had a U-shape impact on FUE. Policies aimed at improving FUE and reducing non-point source pollution should, therefore, focus on improving the social networks of farmers, especially young farmers, strengthening network trust, promoting network learning, network reciprocity and network interaction, strengthening the research and development and extension of green fertilization technology, encouraging farmers to join agricultural cooperative, improving village production conditions, guiding sustainable agricultural production.

Effects of water and fertilizer deficit regulation with drip irrigation at different growth stages on fruit quality improvement of kiwifruit in seasonal arid areas of Southwest China

For a long time, seasonal drought occurs frequently in Southwest China, and the management of water and fertilizer in kiwifruit orchards has no quantitative standards, which seriously affects the yield and quality of kiwifruit. Therefore, the effects of water and fertilizer deficit regulation with drip irrigation (WFDRDI) on the quality of kiwifruit at different growth stages were explored to achieve water and fertilizer saving, and green and efficient production of kiwifruit. We select ‘Jin Yan’ kiwifruit and set two water deficit levels (WD20% and WD40%) and three fertilizer deficit levels (FD15%, FD30% and FD45%) at bud burst to leafing stage (stage I), flowering to fruit set stage (stage II), fruit expansion stage (stage III) and fruit maturation stage (stage IV), respectively, with a full irrigation and fertilization as the control treatment (CK) in 2017 and 2018. Results showed that the WFDRDI at stage II and III had significant effect on fruit physical quality of kiwifruit, specifically, the III-WD40%FD30% and III-WD20%FD45% treatments significantly increased fruit firmness by 13.62 and 15.59% (P<0.05), respectively; the II-WD40%FD15% and III-WD40%FD15% treatments significantly increased dry matter by 8.19 and 6.47% (P<0.05), respectively; the III-WD20%FD15% treatment significantly increased single fruit weight and fruit volume by 9.33 and 12.65% (P<0.05), respectively; the II-WD20%FD15% treatment significantly increased fruit water content by 1.99% (P<0.05). The WFDRDI had an obvious effect on fruit chemical quality of kiwifruit. The III-WD20%FD45%, IV-WD40%FD15% and IV-WD20%FD30% treatments significantly increased vitamin C (Vc) content by 69.96, 36.96 and 34.31% (P<0.05), respectively; the III-WD40%FD15% and IV-WD40%FD15% treatments significantly increased total soluble solid (TSS) content by 3.79 and 17.05% (P<0.05), respectively, and significantly increased soluble sugar content by 28.61 and 34.79% (P<0.05), respectively; the contents of fructose, glucose and sucrose also had a significantly increasing trend, which was increased significantly by 5.58–19.63%, 40.55–60.36% and 54.03–54.92% in the III-WD40%FD15% and IV-WD40%FD15% treatments (P<0.05), respectively; sugar–acid ratio was increased significantly in the IV-WD40%FD15% treatment by 64.65% (P<0.05). The degree and duration of water and fertilizer deficit had a comprehensive effect on fruit quality of kiwifruit. The WFDRDI at stage II and III contribute to improving fruit physical quality, and the threshold of water and fertilizer deficit were 20 and 15%, respectively; stage III and IV are the critical periods for improving fruit chemical quality by water and fertilizer coupling effect, and the threshold of water and fertilizer deficit were 40 and 15%, respectively. Therefore, aiming at precise water and fertilizer saving, the I-WD20%FD30%, II-WD40%FD15%, III-WD40%FD15% and IV-WD40%FD15% treatments under WFDRDI during the whole growth period of kiwifruit were the best mode to improve quality and production of kiwifruit.

Antifungal and elicitor activities of p-hydroxybenzoic acid for the control of aflatoxigenic Aspergillus flavus in kiwifruit

Aspergillus flavus not only reduces kiwifruit production but also synthesizes carcinogenic aflatoxins, resulting in a relevant threat to human health. p-Hydroxybenzoic acid (pHBA) is one of the most abundant phenolics in kiwifruit. In this study, pHBA was found to reduce A. flavus mycelial growth by blocking the fungal mitotic exit network (MEN) and cytokinesis and to inhibit the biosynthesis of aflatoxins B1 and B2. The application of pHBA promoted the accumulation of endogenous pHBA and induced oxidative stress in A. flavus-infected kiwifruit, resulting in an increase in H2O2 content and catalase (CAT) and superoxide dismutase (SOD) activities. Preventive and curative treatments with 5 mM pHBA reduced A. flavus advancement by 46.1% and 68.0%, respectively. Collectively, the antifungal and elicitor properties of pHBA were examined for the first time, revealing new insights into the role of pHBA in the defense response of kiwifruit against A. flavus infection.

Assessment of the Biocontrol Potential of Bacillus velezensis WL-23 against Kiwifruit Canker Caused by Pseudomonas syringae pv. actinidiae.

Kiwifruit canker disease, caused by Pseudomonas syringae pv. actinidiae (Psa), is the main threat to kiwifruit production worldwide. Currently, there is no safe and effective disease prevention method; therefore, biological control technologies are being explored for Psa. In this study, Bacillus velezensis WL-23 was isolated from the leaf microbial community of kiwifruit and used to control kiwifruit cankers. Indoor confrontation experiments showed that both WL-23 and its aseptic filtrate had excellent inhibitory activity against the main fungal and bacterial pathogens of kiwifruit. Changes in OD600, relative conductivity, alkaline proteinase, and nucleic acid content were recorded during Psa growth after treatment with the aseptic filtrate, showing that Psa proliferation was inhibited and the integrity of the cell membrane was destroyed; this was further verified using scanning electron microscopy and transmission electron microscopy. In vivo, WL-23 promoted plant growth, increased plant antioxidant enzyme activity, and reduced canker incidence. Therefore, WL-23 is expected to become a biological control agent due to its great potential to contribute to sustainable agriculture.

Comparison of comprehensive performance of kiwifruit production in China, Iran, and Italy based on emergy and carbon emissions

Extensive kiwifruit farming patterns worldwide are generating increasing environmental stress and thus hindering their sustainability. Comprehensive performance, based on resource efficiency and resource structure, pollutant emissions’ impact and carbon emission, is still not clear for this planting system. Therefore, this study proposes a comprehensive evaluation of kiwifruit planting systems by combining emergy analysis with carbon emission accounting method. The proposed approach not only considers the resource efficiency and resource structure of this planting system, as well as its carbon emission intensity, but also describe tradeoffs among emergy sustainability, pollutant emissions’ impacts and carbon emission intensity using the proposed index - Co-benefit index (CBI). Finally, four kiwifruit planting systems from China (Kiwifruit planting system in Sichuan province (SCPS) and Kiwifruit planting system in Shaanxi (SXPS)), Italy (Kiwifruit planting system in Italy (ITPS)) and Iran (Kiwifruit planting system in Iran (IRPS)), as case studies, are investigated using the presented approach. The study results show that (1) carbon emission intensity (CO2-eq/kg product) embodies trends of SXPS (0.16) > ITPS (0.15) > SCPS (0.12) > IRPS (0.11); (2) pollutant emissions’ impact intensity follows the trends of SXPS (2.54E+14) > ITPS (1.58E+14) > SCPS (8.29E+13) > IRPS (2.56E+13) in units of sej/t product; (3) environmental sustainability reveals trends of IRPS > ITPS > SXPS > SCPS mainly due to different environmental load rates. Generally, the four systems are not sustainable in the long term due to their high dependence on nonrenewable resources (especially labor and services (L&S) and chemical fertilizers); (4) results of Co-benefit index reflect the trends of IRPS > SCPS > ITPS > SXPS accordingly. Some targeted measures are proposed for SCPS, SXPS and ITPS. Considering low sustainability level, it is urgent for the four kiwifruit planting systems to further improve their utilization rate of chemical fertilizer and resource structure in the future.

Analyzing On-Farm Spatiotemporal Distribution of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) Populations from a Precision Agriculture Perspective.

The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is native to Japan, China, Taiwan, and Korea. Its dispersion from Asia to the United States of America and Europe caused serious damage to fruit, vegetables, and high-value crops. In Greece, damages are reported in kiwi orchards in the regions of Pieria and Imathia, which are the main production areas of kiwifruit. Greek kiwifruit production is expected to increase twofold within the next years. The aim of this research is to study the terrain and canopy properties that may have an impact on the development of H. halys populations. Thus, five kiwi orchards in total were selected in the regions of Pieria and Imathia. Τen traps were installed from early June to late October within each selected kiwi orchard-two types of traps at every side of the orchards and the center. The installed traps were examined weekly and the number of the captured H. halys was recorded. During the same days, sentinel satellite images were analyzed to calculate the vegetation index, NDVI (Normalised Difference Vegetation Index), and NDWI (Normalised Difference Water Index). The results showed population variability within the kiwi orchards since the population of H. halys was higher in areas with high NDVI and NDWI values. Additionally, our research revealed that H. halys prefers to develop populations at higher altitudes at both regional and field scales. The results of this research can be used to reduce damages by H. halys in kiwi orchards using different rates of pesticides depending on the prediction of the population size. There are multiple benefits of the proposed practice, such as a reduction in the production cost of kiwifruits, an increase in farmers' profit, and environmental protection.

Antibacterial mechanism of the novel antimicrobial peptide Jelleine-Ic and its efficacy in controlling Pseudomonas syringae pv. actinidiae in kiwifruit.

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) poses a severe threat to kiwifruit production. Because of the insufficient efficacy and environmental safety of available treatments, novel antibacterial agents should be urgently developed. Antimicrobial peptides (AMPs) can be used as antimicrobials for disease control. In this study, we designed a novel AMP, Jelleine-Ic, and evaluated its antibacterial activity and mechanism of action against Psa. Jelleine-Ic with a half maximal effective concentration of 1.67 μg/mL exhibited stronger antibacterial activity than did parent Jelleine-I. Jelleine-Ic targeted the Psa membrane, increased membrane permeabilization, and dissipated membrane potential, resulting in calcium leakage. Electron microscopy revealed that Jelleine-Ic disrupted cell morphology and caused intracellular alterations. Moreover, this AMP penetrated the cell membrane, bound to DNA, and reduced the expression of genes related to DNA replication and repair. Jelleine-Ic also reduced esterase activity and induced intracellular reactive oxygen species generation. This peptide inhibited the development of Psa canker. The control efficiency of Jelleine-Ic against Psa in the leaf discs and leaves of kiwifruit was 81.83% and 70.53%, respectively, which was superior to that of the commercial agricultural streptomycin. Furthermore, Jelleine-Ic upregulated the expression of kiwifruit defense genes (PR-10 and WRKY70a). Jelleine-Ic effectively controls Psa in vitro and in vivo, and may be developed as a bactericide for plant disease control. This article is protected by copyright. All rights reserved.