Reciprocal Combination Research Articles

A novel equivalent reciprocal convex combination technique to sampled‐data master–slave synchronization for chaotic Lur'e systems with time‐varying delays

AbstractFor a class of master–slave (M‐S) systems in chaotic Lur'e systems with time‐varying delays, a sampled‐data synchronization controller is designed, and a new synchronization stability condition is proposed in the form of linear matrix inequality. A novel Lyapunov‐Krasovskii functional (LKF) is constructed by using the looped‐functional method, and the positive definiteness condition of LKF including sampled‐data parts is exchanged with a looping condition by constructing a functional, which should be equal at adjacent sampling times. The M‐S synchronization condition is obtained utilizing the equivalent reciprocal convex combination approach combined with Bessel‐Legendre integral inequality to estimate the LKF derivative. Different from previous methods, due to fully utilizing both nonlinearity and state information at the sampling time via the integral of error systems from the sampling time to current one, the M‐S synchronization condition is less conservative, and obtained sampled‐data controller possesses a longer sampling period. Finally, two numerical examples verify the superiority and validity of the approach.

Collaborative game-based task offloading scheme in the UAV-TB-assisted battlefield network platform

In the sixth-generation (6G) wireless networks, the use of unmanned aerial vehicles (UAVs) and tethered balloons (TBs) to assist cellular networks has attracted considerable attentions due to their dynamic and quick deployment with their relative low cost. In this article, we propose a new task offloading scheme for smart devices in the modern battlefield area. By the integrative platform of TBs, UAVs and smart devices, the main challenges are (i) providing a task splitting algorithm for the partial offloading service, and (ii) develop a TB resource sharing algorithm to handle the offloading requests. For convenient wireless communications, UAVs work as relay nodes between TBs and individual devices. To achieve a mutually desirable solution, our proposed scheme is formulated as cooperative game models. First, the sequential Raiffa bargaining solution is applied to split the computation-intensive task of each smart device in the battlefield area. Second, the average-surplus value is adopted to effectively share the TB computing resource. Based on the reciprocal combination of two cooperative game solutions, we explore the sequential interaction of TBs, UAVs and battlefield devices, and jointly design our integrated control scheme for offloading services. According to the synergy effect, our hybrid approach can provide a fair-efficient solution in the UAV-TB-assisted battlefield network infrastructure. Finally, extensive simulations are conducted, and the results demonstrate the superiority of our proposed scheme over the existing baseline protocols.

Recent Advances in Assessing the Clinical Implications of Epstein-Barr Virus Infection and Their Application to the Diagnosis and Treatment of Nasopharyngeal Carcinoma.

Reports about the oncogenic mechanisms underlying nasopharyngeal carcinoma (NPC) have been accumulating since the discovery of Epstein-Barr virus (EBV) in NPC cells. EBV is the primary causative agent of NPC. EBV-host and tumor-immune system interactions underlie the unique representative pathology of NPC, which is an undifferentiated cancer cell with extensive lymphocyte infiltration. Recent advances in the understanding of immune evasion and checkpoints have changed the treatment of NPC in clinical settings. The main EBV genes involved in NPC are LMP1, which is the primary EBV oncogene, and BZLF1, which induces the lytic phase of EBV. These two multifunctional genes affect host cell behavior, including the tumor-immune microenvironment and EBV behavior. Latent infections, elevated concentrations of the anti-EBV antibody and plasma EBV DNA have been used as biomarkers of EBV-associated NPC. The massive infiltration of lymphocytes in the stroma suggests the immunogenic characteristics of NPC as a virus-infected tumor and, at the same time, also indicates the presence of a sophisticated immunosuppressive system within NPC tumors. In fact, immune checkpoint inhibitors have shown promise in improving the prognosis of NPC patients with recurrent and metastatic disease. However, patients with advanced NPC still require invasive treatments. Therefore, there is a pressing need to develop an effective screening system for early-stage detection of NPC in patients. Various modalities, such as nasopharyngeal cytology, cell-free DNA methylation, and deep learning-assisted nasopharyngeal endoscopy for screening and diagnosis, have been introduced. Each modality has its advantages and disadvantages. A reciprocal combination of these modalities will improve screening and early diagnosis of NPC.

Consensus Congestion Control for Ad Hoc Networks: Time-Delay and Saturation

This work focuses on the congestion control design for ad hoc networks affected by time-delay and asymmetrical input saturation. First, an innovative general TCP/AQM model for mobile and wireless ad hoc networks (MANET/WANET) is proposed using graph theory and TCP/AQM system dynamics in a dumbbell topology. Next, a new characteristic condition for sector linearity is developed, which plays the role of a specification to be checked and allows us to assume that the dynamics of the nodes are not saturated. Finally, we propose a new consensus-based congestion control protocol while satisfying the input constraints based on the Lyapunov method, the new sector of linearity condition, the Bessel Legendre-based integral inequality, and the reciprocal convex combination. The proposed results have the advantage of being given as a set of linear matrix inequality (LMI) conditions, which can be solved using convex optimization toolboxes. The merits of the theory are evaluated with the help of various real and challenging scenarios with the use of MATLAB and NS3.

Radio resource management scheme in radar and communication spectral coexistence platform

In vehicular environments, the cooperation of radar and communications has been recognized as a promising solution to alleviate the shortage of spectrum resources. In this paper, we investigate the joint radar sensing and communication (JSC) system based on the cooperative spectrum sharing strategy. Via the full cooperation between both radar sensing and wireless communication functionalities, we can avoid the under-utilization of spectral resource while improving system efficiency. To implement our JSC control scheme, we focus on coalitional bargaining solutions according to the cooperative game theory. Especially, the coalitional Nash bargaining solution (CNBS) and coalitional Kalai-Smorodinsky bargaining (CKSBS) are employed to get a mutually desirable solution in the radar-communication coexistence platform. The main ides of CNBS is adopted to distribute the spectrum resource among roadside units, and both radar and communication functions in each individual vehicle. The concept of CKSBS is applied to allocate the spectrum resource for vehicles in order to maximize their payoffs. In the proposed scheme, the CNBS and CKSBS work together to share the surplus of a coalition with the fairness and efficiency properties. The main contribution of our proposed approach is the reciprocal combination of the CNBS and CKSBS to obtain the synergy effect. Finally, numerical results are provided to verify the effectiveness of the proposed scheme for the JSC system operations.

Fluorescently labelled pepino mosaic virus strains share infected tissues and colocalize in cellular aggregates reminiscent of viral replication complexes

Mixed infections of pepino mosaic virus (PepMV) isolates from the EU and CH2 strains are frequent in tomato crops. An asymmetric antagonistic relationship has been described between these strains, making their in planta interaction worthy of study. The aim of this work was to verify if PepMV isolates labelled with fluorescent proteins recapitulate the interactions described for wild type isolates and, if so, to determine the proportion of cells infected with each isolate in single and mixed infected plants. Infectious clones were prepared for PepMV-CH2-GFP and -EU-TagRFP, and also for their reciprocal combination, PepMV-CH2-TagRFP and -EU-GFP, and used to inoculate Nicotiana benthamiana plants. The accumulation of viral RNA followed trends that differed from wild type viruses, with the PepMV-EU-GFP and -CH2-TagRFP pair reproducing more closely the wild type interaction. Protoplasts were isolated from leaves that were systemically infected with PepMV-EU-GFP, -CH2-TagRFP, or both, and flow cytometry was used to determine the proportion of cells infected with each tagged isolate. A significant proportion (16.6%) of cells were found to be infected with both, without strong evidence of virus exclusion in coinfections, as could have been expected for related viruses; in fact, cellular structures reminiscent of viral replication complexes were found to be labelled with both fluorescent reporters.

Inheritance of spike color in einkorn wheat (Triticum monococcum L.)

Aim: specify the spike color inheritance in einkorn wheat (Triticum monococcum L.) hybrids. Methods: reciprocal hybrids between the black-spikeed UA0300282 and white-spikeed UA0300311 cultivated einkorn accessions were created with the use of the “single cross” method. Four generations were analyzed using the segregation analysis method: P1, P2, F1, and F2 at autumn and spring sowing. Results: it was found that for the combination UA0300311 × UA0300282 at autumn sowing, the most suitable inheritance model is MX2-EA-AD, which implies the presence of two main genes with an equal additive effect plus polygene systems with an additive-dominant effect. In the plants of spring sowing, spike color is described by the MX2-CD-AD model, which suggests the presence of two major genes with full dominant effect plus polygenes with additive-dominant effect. In the reciprocal combination UA0300282 × UA0300311, the optimal model that describes best the spike color dispersion in plants of autumn sowing is MX2-ADI-AD, which suggests the presence of two main genes with an additive-dominant-epistatic effect plus polygenes with the additive-dominant effect. Distribution of the spring-sowing plants in terms of the spike color is well described by the MX2-ADI-ADI model – two main genes with an additive-dominant-epistatic effect plus a system of polygenes also with an additive-dominant-epistatic effect. The genes manifest themselves differently in the trait control depending on the weather conditions determined by the sowing time. In the group of direct combination plants (UA0300311 × UA0300282) of autumn sowing, heritability determined by the main gene is 97%, while that determined by polygenes is 2.7%; at spring sowing, these values are 67% and 32% respectively. In the reciprocal combination (UA0300282 × UA0300311) of autumn sowing, the main genes heritability effect is 99%, and the polygenic system accounts for 1%; in plants of spring sowing, respectively, 72%, and 28%. Conclusions: on the basis of the spike color expressiveness in the crossing combination of the einkorn kinds of wheat UA0300311 × UA0300282, the parental forms differ in two main genes and polygenes. The ratio of spike color heritability components depends on the growing conditions: at autumn sowing, 97–99 % of heritability is determined by the main genes, the polygenes account for 1–3 % of phenotypic variability; at spring sowing, the heritability component increases to 28–33 % due to the polygenic complex.

INHERITANCE OF PLANT HEIGHT IN EINKORN WHEAT BY RESULTS OF SEGREGATION ANALYSIS

The genetic control of plant height – important trait associated with yield – is practically not studied in diploid wheats. In this paper, using reciprocal crosses between two Triticum monococcum accessions – var. monococcum (UA0300311) and var. nigricultum (UA0300282) in autumn and spring sowing, inheritance of the plant height is studied. The sowing period significantly affects the expression of einkorn plant height. Data from the generations P1, P2, F1, F2 were used for segregation analysis. For a combination of UA0300311 × UA0300282, the optimal models for plant height inheritance are: at autumn sowing – one main gene with a negative complete dominant effect, its additive effect is –8.05; at spring sowing – one main gene with an additive-dominant effect, its additive effect is –24.51. For the reciprocal combination UA0300282 × UA0300311, at autumn sowing, the optimal model of plant height was one main gene with an equal additive-dominant effect, it additive effect is 10.94; at spring sowing – one main gene with a negative complete dominant effect, its additive effect is –18.37. The heritability was in all cases from 96.52% to 99.70%. The high dispersion of the trait in the second hybrid generation suggests that the studied parental forms differ not only in the main gene, as follows from the results of segregation analysis, but also in the system of modifier genes with a weak effect.

WITHDRAWN: Auction, Learning and Bargaining based Control Scheme for Edge assisted Metaverse System

Edge computing (EC) has emerged as a cost-effective platform to enhance the computing capability of hardware-constrained IoT devices. Recently, EC-assisted Metaverse system is regarded as the next-generation Internet paradigm that allows humans to play, work, and socialize in an alternative virtual world. With the help of ubiquitous wireless connections and powerful EC technologies, the Metaverse system effectively manages the interactions among system agents. In this study, we present a new intelligent Metaverse control scheme, which adopts three control approaches. First, McAfee double auction is applied to handle the collected data trading between service providers and IoT devices. Second, Q-learning algorithm is adopted to decide the power level of each IoT device. Third, the status quo proportional bargaining solution is used to provide a proper resource allocation problem for the devices’ wireless communications. Based on the reciprocal combination of auction, learning and bargaining algorithms, we explore the sequential interaction of system agents, and jointly design an integrated control scheme to strike an appropriate Metaverse performance balance. According to the synergy effect, our hybrid protocol is a novel method in the EC-assisted Metaverse infrastructure. Finally, extensive simulations demonstrate that our approach can lead to achieve a mutually desirable solution with a good balance between efficiency and fairness comparing with the currently published Metaverse system control schemes.

Inheritance of quantitative traits in F1 hybrids of einkorn wheat

Aim. Determine the type of quantitative traits inheritance in einkorn wheat F1 hybrids. Methods. Hybridological and morphometric analyses. Results. In the combination ♀T. urartu × ♂T. sinskajae, the hybrid caryopses did not set; in the reciprocal combination, the set rate was 28 %. In combinations involving T. boeoticum, T. monococcum, T. sinskajae the setting ranged from 37 % to 54 %. In different combinations, hybrids showed overdominance, hybrid depression, dominance of parental traits with a higher and lower trait value, rarely intermediate inheritance. The combinations in which T. sinskajae is involved are of interest due to heterosis in grain weight of per ear, spikelet number in ear, grain number in ear and less hullness. At the same time, the dominance degree for this trait correlates with the indicators of the dominance degree in length, width and area of flag leaf (r: 0.62–0.71). Conclusions. Einkorn hybrids with the participation of naked wheat T. sinskajae are promising in terms of spikelet number per ear, grain number per ear, ear weight, grain weight per ear, reduced hullness.

Investigating the Mechanism of Unilateral Cross Incompatibility in Longan (Dimocarpus longan Lour.) Cultivars (Yiduo × Shixia).

Longan (Dimocarpus longan Lour.) is an important subtropical fruit tree in China. Nearly 90% of longan fruit imports from Thailand are from the cultivar Yiduo. However, we have observed that there exists a unilateral cross incompatibility (UCI) when Yiduo is used as a female parent and Shixia (a famous Chinese cultivar) as a male parent. Here, we performed a comparative transcriptome analysis coupled with microscopy of pistils from two reciprocal pollination combinations [Shixia♂ × Yiduo♀(SY) and Yiduo♀ × Shixia♂(YS)] 4, 8, 12, and 24 h after pollination. We also explored endogenous jasmonic acid (JA) and jasmonyl isoleucine (JA-Ile) levels in pistils of the crosses. The microscopic observations showed that the UCI was sporophytic. The endogenous JA and JA-Ile levels were higher in YS than in SY at the studied time points. We found 7,251 differentially expressed genes from the transcriptome analysis. Our results highlighted that genes associated with JA biosynthesis and signaling, pollen tube growth, cell wall modification, starch and sucrose biosynthesis, and protein processing in endoplasmic reticulum pathways were differentially regulated between SY and YS. We discussed transcriptomic changes in the above-mentioned pathways regarding the observed microscopic and/or endogenous hormone levels. This is the first report on the elaboration of transcriptomic changes in longan reciprocal pollination combination showing UCI. The results presented here will enable the longan breeding community to better understand the mechanisms of UCI.

A Sampling Load Frequency Control Scheme for Power Systems with Time Delays

In this study, we investigate the effectiveness of a robust sampled‐data H∞ load frequency control (LFC) scheme for power systems with randomly occurring time‐varying delays. By using the input‐delay technique, the sampled‐data LFC model is reformulated as a continuous time‐delay representation. Then, Bernoulli‐distributed white noise sequences are used to describe randomly occurring time‐varying delays in the sampled‐data LFC model. Some less conservative conditions are achieved by utilizing the Lyapunov–Krasovskii functional (LKF) and employing Jensen inequality and reciprocal convex combination lemma to ensure the considered power system has mean‐square asymptotic stability under the designed control scheme. The derived results are based on linear matrix inequalities (LMIs) that can readily be solved using the MATLAB LMI toolbox. The criteria obtained are used to analyze the upper bounds for time delays, and a comparison study to validate the efficacy of the presented method is presented.

METHODS FOR FORECASTING DEMAND IN REPAIRING AN AIRLINE’S REPAIRABLE LINE REPLACEABLE UNIT PARTS

Scattered failure frequency, variable and complex influencing factors, and a low accuracy in predicting inventory demand are characteristics of line replaceable unit (LRU) parts. Some high-priced repairable LRU (HR-LRU) parts have a considerable impact on the cost of aircraft spare parts.This study presents procedures to identify the optimal model for forecasting the demand for HR-LRU parts. First, a traditional prediction model, seven single measurement models, and four combined models were selected and used to predict failure data. Subsequently, evaluating indexes were selected for assessment to obtain the optimal model. Finally, we compared the actual and predicted values to verify the conclusions drawn during the previous evaluation step. The results indicated that, among the single models, the negative binomial regression model and the Holt-Winters model were most suitable for HR-LRU parts. The SSE (sum of squares error) and MAE (mean absolute error) of the negative binomial regression were the lowest at 118.4114 and 1.97352 respectively, and the Holt-Winters model’s MAE was the lowest at 1. 13270. The IOWA operator prediction model and the error reciprocal variable weight combination method produced predictions closest to the actual values among the combined models. In addition to constructing a set of processes to prediction, we also discuss the fit of different methods, the reasons for the change in the guaranteed rate, and the reasons for the occurrence of special years. We also compare the similarities and differences between this article and other papers.

Development and regeneration of wheat-rice hybrid zygotes produced by in vitro fertilization system.

Summary Hybridization plays a decisive role in the evolution and diversification of angiosperms. However, the mechanisms of wide hybridization remain open because pre‐ and post‐fertilization barriers limit the production and development of inter‐subfamily/intergeneric zygotes, respectively.We examined hybridization between wheat and rice using an in vitro fertilization (IVF) system to bypass these barriers. Several gamete combinations of allopolyploid wheat–rice hybrid zygotes were successfully produced, and the developmental profiles of hybrid zygotes were analyzed.Hybrid zygotes derived from one rice egg cell and one wheat sperm cell ceased at the multicellular embryo‐like structure stage. This developmental barrier was overcome by adding one wheat egg cell to the wheat–rice hybrid zygote. In the reciprocal combination, one wheat egg and one rice sperm cell, the resulting hybrid zygotes failed to divide. However, doubling the dosage of rice sperm cell allowed the hybrid zygotes to develop into plantlets. Rice chromosomes appeared to be progressively eliminated during the early developmental stage of these hybrid embryos, and c. 20% of regenerated plants showed abnormal morphology.These results suggest that hybrid breakdown can be overcome through optimization of gamete combinations, and the present hybrid will provide a new horizon for utilization of inter‐subfamily genetic resources.

ASSESSING THE COMBINING ABILITY OF RICE GENOTYPES IN F1 GENERATION USING COMPLETE DIALLEL CROSS

A complete diallel analysis was carried out to determine combining ability of Shandar, NIA-Mehran, NIA-19/A, KS-282 and Shua-92 rice varieties in F1 during 2017. The objective of the study was to identify potential recombinants for future rice breeding program. The research was conducted at Nuclear Institute of Agriculture, Tandojam. Genotypic mean squares were significant (P ?0.01) for all of the traits i.e.; days to heading, days to maturity, plant height, number of tillers plant-1, panicle length, grains panicle-1 and grain yield plant-1 indicating genetic variation. Importance of both additive and non-additive gene action was found with preponderance of additive genetic effects in expression of traits studied. Showing negative GCA effects, NIA-Mehran, NIA-19/A and Shua-92 proved better parent varieties for developing early maturity. While, NIA-Mehran, KS-282 and Shua-92 for developing short stature genotypes. While, Shandar remained the best combiner for yield and yield associated traits with higher positive GCA effects. Cross combination of Shandar × KS-282 was the best with higher negative effects for days to heading and maturity and higher positive effects for grain yield plant-1. NIA-Mehran × Shua-92 gave the highest negative SCA effects indicating best combination for short stature. In case of number of tillers plant-1 and grains panicle-1, the cross NIA-19/A × KS-282 was the better combination with the highest positive SCA effects. Shandar × NIA-Mehran manifested the highest value for panicle length. Findings of reciprocal SCA revealed that the reciprocal cross combination of Shua-92 × Shandar was fruitful illustrating negative effects for days to heading and maturity. While, KS-282 × NIA-Mehran was the best reciprocal combination for yield and yield associated traits. It is concluded that rice varieties Shandar and NIA-Mehran could be used to improve yield contributing traits in rice, while, NIA-Mehran and KS-282 may be used to improve early maturity and short stature in rice crop.

Modeling on Social Health Literacy Level Prediction.

Nowadays, the health level of residents has become the focus of people's attention. Under the background of the development of health service from “disease-centered” to “health-centered,” it is very important to improve the level of urban health and clarify the factors affecting urban health. Therefore, this paper quantifies the relationship between residents' health literacy level and environment, average life expectancy, infectious disease mortality, and other indicators by selecting appropriate indicators and establishing a mathematical model. Based on the reciprocal linear combination of the collected index data and the corresponding health level value, the prediction model of social health literacy level (SPM) was established, and the qualitative prediction and quantitative analysis of citizens' health literacy level were studied in depth. Based on the SPM model, we can roughly predict the level of health literacy in a region only based on the main variables identified in this paper. The consistency of the experiment shows that the model is effective and robust, and it reveals that environmental factors are the most important factors affecting residents' health literacy level. The actual data show that THE SPM model is a timely and reasonable framework to measure the health literacy level of residents.

Fault Detection and Controller Co-Design for Nonlinear Delayed Switched Systems Based on Mode-Dependent Average Dwell Time Under Asynchronous Switching

In this paper, the fault detection (FD) and controller co-design problem is investigated for continuous-time nonlinear delayed switched systems based on mode-dependent average dwell time (MDADT) under asynchronous switching. Different from the average dwell time (ADT) method, the adopted MDADT switching law in which each subsystem has its own ADT, is more suitable for practical applications. Meanwhile, a closed-loop control strategy including both the controller and the fault detection filter, are designed simultaneously by using piecewise Lyapunov-Krasovskii function (LKF), MDADT method and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H_\infty }$ </tex-math></inline-formula> control technique. Furthermore, both the Wirtinger integral inequality and an advanced reciprocal convex combination method are utilized to provide a tighter estimation on continuous derivative of certain LKF, leading to a less conservative result, and the solution of the parameters for the controller and fault detection filter (FDF) is characterized in the feasibility of LMI problem. Finally, a practical designed solution on the highly maneuverable aircraft technology indicates the proposed technique is valid and superior.

Fault estimation for continuous‐time non‐linear switched systems with time‐varying delay based on intermediate estimator

In this work, the fault estimation (FE) problem is studied for continuous-time non-linear switched systems with time-varying delay over fading channel under average dwell time switching. A novel FE method based on the intermediate estimator is used to eliminate the observer matching constraint condition, where an intermediate variable is introduced to estimate the state and fault simultaneously. Meanwhile, the fading channel of data transmission is modelled as Bernoulli distributed white sequences. Furthermore, because the observer matching conditions are eliminated by the intermediate estimator, both the wirtinger integral inequality and an advanced reciprocal convex combination method are utilised to provide a tighter estimation on continuous derivative of certain Lyapunov–Krasovskii function over fading channel, leading to a less conservative result. Moreover, the solution of the parameters for intermediate estimator is characterised in the feasibility of linear matrix inequality problem. Finally, two numerical examples indicate the proposed technique is valid and superior.

Application of Hybridization Breeding Technique for Fire Blight Resistance on Cydonia Oblonga: A Base Study on Susceptibility, Heterosis, and Heterobeltiosis Parameters

ABSTRACT Erwinia amylovora: Burrill. is the most important disease affecting quince cultivation and breeding of resistant varieties is seen as the key solution. As a result of hybridizations, 223 hybrids were obtained from 9 different combinations and susceptibility indexes (SI) of these hybrids were determined by artificial inoculations. Among the tested seven parental cultivars, Ege 25, Altın 35, Zeybek 35, and Ayva B-35 were found fire blight resistant while others were detected as moderately susceptible. SI of hybrids were changed between 14.77 and 52.94% regardless of hybrid combinations and 77.60% of obtained hybrids took place in resistant (10.1–30%) group. Reciprocal combinations showed that using resistant cultivar as a male parent was more effective than using maternal parent for transferring resistance. Heterosis (Ht) rates between combinations were found significant (p < .0004), while heterobeltiosis (Hbt) were not (p < .0623). Ht and Hbt ranged between −2.82–13.54 and −4.20–6.72 in populations, respectively. The maximum and significant heterotic effect was observed in Quince A × Ayva B-35 and its’ reciprocal combination. In moderately susceptible × resistance combination, 83.33% of F1 were determined to be resistant. On the other hand, hybrids from resistance × resistance combination were distributed in three groups as resistant, moderately susceptible and susceptible. According to these results, it could be said that (1) fire blight resistance genes in quince are recessive, (2) use of resistant varieties as pollinators is more successful in transferring resistance to hybrids, (3) open pollination treatment is an essential and easy way in terms of obtaining resistant hybrids if the orchard has resistant pollinator, and (4) heterobeltiosis for fire blight resistance is important.

An Analysis on Some Reciprocal Pear Hybridization Combinations in Terms of Transferring Resistance to Fire Blight

Since it has a wide variety, pear can be grown in all temperate zones and high-altitude areas of tropical and subtropical climates of the Earth. On the other hand, most of the cultured pear varieties are susceptible to fire blight caused by Erwinia amylovora, and their susceptibility is threatening pear cultivation. The lack of a certain solution to fire blight, the harmful effects of the chemicals on environment and human health and the increasing demand for organic products, give priority to breeding new resistant rootstocks and varieties in control of the disease. Due to the polygenic nature of fire blight resistance and the complexity of its mechanism, controlled hybridization is generally used in breeding programs. In order to determine the effect of the parents for the transmission of fire blight resistance, hybridizations are also carried out reciprocally. In the study which was carried out for this aim, susceptibility levels of the F1 hybrids, obtained from the reciprocal combinations of fire blight resistant ’Kieffer’ and the susceptible ’Williams’, ’Santa Maria’ and ’Akca’ cultivars, were evaluated. While ’Kieffer’ x ’Santa Maria’ was found the most resistant combination to fire blight, ’Akca’ x ’Williams’ was found as the most susceptible one. In addition, it has been determined that F1 hybrids obtained from ’Kieffer’ x ’Santa Maria’ and ’Akca’ x ’Williams’ hybridization combinations and their reciprocals are different in terms of disease resistance, while there was no difference in resistance in F1 hybrids of ‘Williams’ x ’Santa Maria’ combination and its reciprocal combination.