Functional agrobiodiversity in apple and pear pest management in Belgium

In the framework of both ‘Eco-Orchard’ CORE Organic+ ERA NET project, and a research project with financial support of the Rural Development Administration (RDA) of the Republic of Korea, a study started in 2015 with as first aim the comparison of the type and abundance of beneficials in Belgium orchards under conventional and organic production systems applying different Functional AgroBiodiversity (FAB) techniques and this during two growing seasons. The second aim of this study is to collect existing information about FAB and its management techniques to improve knowledge and practical experience between scientists, advisors and owners of the fruit orchards. The final aim of this study focus on the co-design and establishment of innovative fruit-based agroforestry cropping systems, including the best registered FAB techniques, in order to conduct a long-term sustainability study of such systems. The first results concerning relationship between beneficial’s and FAB techniques, show that (i) beneficial’s are more abundant (x 3.1) in organic compared to conventional orchards and (ii) the diversity of beneficial are significantly higher (x 2.2) in organic compared to conventional orchards. A total of 34 techniques have been described. The most Functional Agro-Biodiversity techniques, as ranked by farmers, are (i) flower strip, (ii) hedgerows, (iii) to reduce pesticides uses and (iv) to adapt interrow mowing. Concerning innovative fruit-based agroforestry cropping system, an experimental agroforestry orchard was planted in 2014 at Gembloux (Belgium) with the aim of testing various hypotheses. (i) a mixture of selected robust fruit and vegetable cultivars creates a functional biodiversity that significantly reduces the risk of pest and disease damages; (ii) the useful impact on soil functions and biological processes; and (iii) where distances between vegetables and trees in intensified alley-cropping systems are optimized, tree shading does not reduce light levels below the threshold of light saturation

Detection of Internal Browning Disorder in ‘Greensis’ Pears Using a Portable Non-Destructive Instrument

Internal browning caused by prolonged cold storage poses a significant challenge to the visual appearance and flavor of Asian pears, which are economically valuable and a primary fruit exported from Korea. To address this issue, we established a cost-effective portable non-destructive piece of testing instrument using visible and near-infrared spectroscopy, focusing on the detection and discrimination of internal browning in ‘Greensis’ pears. Our investigation underscores the challenge of visually confirming browning, necessitating alternative methods for accurate assessment. Through comprehensive analysis involving three to four segments of 32 ‘Greensis’ pears, a robust calibration equation was derived. By employing partial least square regression on the absorption spectra within a 650–950 nm range, we developed a predictive model for detecting and quantifying browning. Through principal component analysis, normal pears were distinctly segregated from those exhibiting browning symptoms (discrimination accuracy of 95%). Furthermore, we established that pears with a browning index of 25 ± 2.0 are highly susceptible to browning following extended cold storage. Consequently, our proposed portable non-destructive instrument serves as a pivotal tool for farmers and fruit distributors, enabling efficient and precise selection of high-quality pears in an instance. Overall, our study introduces a practical solution to a pressing issue in the Asian pear industry

Antifungal Activity of Agro-Materials against Pear Scab (Venturia nashicola) and Pear Rust (Gymnosporangium asiaticum) Fungi

This study was conducted to evaluate the antifungal activity of 19 agro-materials that have been registered for organic cultivation in Korea, after inoculation of pear leaves with Venturia nashicola and Gymnosporangium asiaticum. In V. nashicola, most of the nine agro- materials containing sulfur and copper completely inhibited spore germination, and some of the spores that germinated did not form appressoria. However, in only lime sulfur, Neobordeaux (cupric sulfate), and Wheengaris (sulfur) showed antifungal activity against G. asiaticum. Among the agro-materials containing plant extracts, Wheengarujaba (wood vinegar+spirits+rhubarb) inhibited conidial germination in V. nashicola and G. asiaticum by 100% and 71.6%, respectively. Among the agro-materials containing antifungal microorganisms, Cheongotan (Streptomyces griseus) reduced spore germination rate of V. nashicola to 88.8%; moreover, formation of appressoria or intracellular accumulation was not observed. Application of Topsid (Paenibacillus polymyxa) reduced spore germination rates in V. nashicola and G. asiaticum to 71.0% and 90.6%, respectively, and the formation of appressoria was not observed. Studying the antifungal activity of agro-materials because of cumulative applications under the field conditions is necessary, owing to their contact fungicidal effect and the induced-resistance by microbial metabolites and natural compounds

Fruit Cracking in Pears: Its Cause and Management—A Review

Pears (Pyrus (Rosaceae, Pyrinae) are among the oldest plants cultivated by humans and the second most widely grown fruit worldwide, after apples. They are commercially important fruit trees; over the last few decades, global area, production, and exports have massively increased. However, fruit cracking at an early stage or at maturity is a severe physiological disorder, causing significant economic losses to pear growers. Fruit cracking may be associated with inadequate irrigation, environmental factors, and nutritional deficiencies, particularly those involving B, Ca, Zn, and potash. Fruits can crack during growth and development due to the abrupt temperature changes between day and night, water imbalances, sun exposure, trellis systems, and the color of the fruit packaging. Cracking is more pronounced when the fruit has reached maturity, and no single factor is known to effectively prevent its occurrence. Although fruit cracking poses the risk of great economic losses, research on its cause and management in pears is limited as compared to other fruit crops. Therefore, examining the occurrence of pear fruit cracking in relation to cultivar genetics, fruit composition and quality, the water levels of the soil and water uptake by plants, and the role of micronutrients and plant growth regulators will aid in the development of strategies to reduce fruit cracking in pears. This review briefly summarizes the causes of fruit cracking in pears and possible control strategies

Characterization of Bacillus velezensis RDA1 as a Biological Control Agent against White Root Rot Disease Caused by Rosellinia necatrix

White root rot disease, caused by Rosellinia necatrix, poses a threat to several tree crops; hence, effective and sustainable strategies to control this disease remain warranted. This study identified an effective R. necatrix biocontrol agent by isolating 32 strains from soil samples collected from white root rot-infested organic pear orchards, among which RDA1 exhibited the most potent growth-inhibitory effects. Microbiological and 16S rRNA gene sequencing analyses revealed that the bacterial isolate belonged to the Bacillus genus and exhibited 100% nucleotide sequence similarity with Bacillus velezensis species in the GenBank. This strain showed strong antifungal activity against four Rosellinia necatrix strains and harbored genes essential for lipopeptide, polyketide, and tripeptide bacilysin biosynthesis. RDA1 produced volatile compounds that suppressed the development of phytopathogens and possessed plant growth-promoting traits, such as phosphate solubilization, and indole-3-acetic acid and siderophore production. B. velezensis RDA1 has a significant potential application in sustainable agriculture and can be used to suppress white root rot disease infections and to improve plant growth

Optimal Multi-Antenna Transmission for the Cooperative Non-Orthogonal Multiple-Access System

We investigate the beamforming for the multi antenna cooperative non-orthogonal multiple access (NOMA) system, where an access point (AP) delivers messages for multiple user terminals (UT) with successive interference cancellation (SIC) reception method. Some UTs with multiple antennas cooperate with the AP transmission to improve the diversity and the average power performance. We formally present two optimal beamforming schemes at the AP and at the cooperative UTs. One scheme has no power limitation for the cooperative UTs, while the other one does have such limitation. We guarantee that the rank one beamformer is sufficient to achieve the optimal points so that the proposed schemes have rank one semi-definite programming (SDP) structure. Simulation results show the performance gain of the multi-antenna cooperative NOMA schemes in the sense of diversity and the average power

Optimal Multi-Antenna Transmission for the Cooperative Non-Orthogonal Multiple-Access System

We investigate the beamforming for the multi antenna cooperative non-orthogonal multiple access (NOMA) system, where an access point (AP) delivers messages for multiple user terminals (UT) with successive interference cancellation (SIC) reception method. Some UTs with multiple antennas cooperate with the AP transmission to improve the diversity and the average power performance. We formally present two optimal beamforming schemes at the AP and at the cooperative UTs. One scheme has no power limitation for the cooperative UTs, while the other one does have such limitation. We guarantee that the rank one beamformer is sufficient to achieve the optimal points so that the proposed schemes have rank one semi-definite programming (SDP) structure. Simulation results show the performance gain of the multi-antenna cooperative NOMA schemes in the sense of diversity and the average power

Beamforming for the Successive Relaying-Based Cooperative Non-Orthogonal Multiple Access Transmission

In this paper, a set of cooperative non-orthogonal multiple access (NOMA) transmission schemes is proposed, in which two half-duplex relaying user terminals (UTs) successively deliver the AP signals toward two NOMA UTs. The successive relaying (SR) of two HD relays emulates the full-duplex (FD) relaying transmission such that the whole transmission of one data block is finished in one time slot. Different from FD relaying, where the removal of self-interference (SI) at the relay is challenging, the SR is suffering from cross-relay interference (CRI) between the two HD relays and the handling of this CRI is the key technical challenge. This CRI suppression is implemented by beamforming with multiple antennas at the relaying UTs, while the beamforming also does the role of maximizing the NOMA transmission efficiency. Two beamforming schemes are proposed, where the first method employs semi-definite relaxation (SDR) with four dimensional (4-D) search. Here, the four dimensions come from the four parameters reflecting the CRI levels at the relaying UTs and signal strengths at the NOMA UTs. This scheme alternates until the 4-D search range is reduced and the sum throughput rate saturates. The second method is computationally simpler than the first one since it avoids the SDR and alternation, and it finds the beamformer set in one shot calculation. Both schemes rely on zero forcing of the CRI. These two schemes along with the HDR relay-based cooperative NOMA scheme are compared in the numerical experiments, and the results exhibit their pros and cons in several aspects

Intelligent-Reflecting-Surface-Assisted Multicasting with Joint Beamforming and Phase Adjustment

In this paper, a set of transmission schemes are proposed for the delivery of multicast (MC) signals, in which an intelligent reflecting surface (IRS) assists the transmission from an access point (AP) to a set of multicast users. It is known that the large number of IRS reflecting elements have the potential to improve the transmission efficiency by forming an artificial signal path with strong channel gain. However, the joint optimization of the AP beamformer and the phases of the IRS reflecting elements is challenging due to the non-convex nature of the phase elements as well as the high computational complexity required for a large number of elements. A set composed of two AP beamformer schemes and a set with two IRS phase adjustment algorithms are proposed, which are sub-optimal but less computationally demanding. A semi-definite relaxation (SDR)-based scheme is considered along with a least squares (LS) based one for the AP beamformer design. For the IRS phase adjustment, an LS based optimization and a grouping method for the phase elements are suggested. From these two sets, four combinations of overall optimization can be built, and their performances can be compared with their merits and weaknesses revealed. The signal-to-interference-plus-noise power ratio (SINR) performance results are verified in various parameter conditions by simulation

Relationship of Resistance to Benzimidazole Fungicides with Mutation of β-Tubulin Gene in Venturia nashicola

Pear scab caused by Venturia nashicola has been reported as an important disease of pear resulting in lowering the quality of pear fruits. In this study, it was conducted to investigate the relationship between resistance of V. nashicola and mutation of β-tubulin gene and the fungicide resistance in field isolate group in benzimidazole fungicides. Responce of V. nashicola to carbendazim could be classified into 3 groups as sensitive that does not grow at all on PDA amended with 0.16 μg/ml of carbendazim, low resistance that could not grow in 4.0 μg/ml medium, and high resistance that can grow even at 100 μg/ml. Thirty isolates of V. nashicola collected from 3 regions as Wonju, Naju, and Okcheon were highly resistant to carbendazim. Analysis of the nucleotide sequence of β-tubulin gene of V. nashicola showed that there was no difference in the nucleotide sequence between the sensitive and the low-resistant isolate, but GAG at codon 198 (glutamic acid) was replaced with GCG (alanine) in the high-resistant isolate. Among 10 isolates obtained from the Okcheon, 5 isolates showed the substitution of glycine for glutamic acid, which were resistant to carbendazim, but more sensitive to the mixture of carbendazim and diethofencarb than others. Through these results, all isolates of V. nashicola isolated in pear orchard were found to be resistant to benzimidazoles. Also, mutants E198A and E198G at β-tubulin were found to be important mechanisms of V. nashicola resistance against benzimidazole fungicides