Pear Growers Research Articles

Glutamine Synthetase and Glutamate Synthase Family Perform Diverse Physiological Functions in Exogenous Hormones and Abiotic Stress Responses in Pyrus betulifolia Bunge (P.be)

The unscientific application of nitrogen (N) fertilizer not only increases the economic input of pear growers but also leads to environmental pollution. Improving plant N use efficiency (NUE) is the most effective economical method to solve the above problems. The absorption and utilization of N by plants is a complicated process. Glutamine synthetase (GS) and glutamate synthase (GOGAT) are crucial for synthesizing glutamate from ammonium in plants. However, their gene family in pears has not been documented. This study identified 29 genes belonging to the GS and GOGAT family in the genomes of Pyrus betulaefolia (P.be, 10 genes), Pyrus pyrifolia (P.py, 9 genes), and Pyrus bretschneideri (P.br, 10 genes). These genes were classified into two GS subgroups (GS1 and GS2) and two GOGAT subgroups (Fd–GOGAT and NADH–GOGAT). The similar exon–intron structures and conserved motifs within each cluster suggest the evolutionary conservation of these genes. Meanwhile, segmental duplication has driven the expansion and evolution of the GS and GOGAT gene families in pear. The tissue–specific expression dynamics of PbeGS and PbeGOGAT genes suggest significant roles in pear growth and development. Cis–acting elements of the GS and GOGAT gene promoters are crucial for plant development, hormonal responses, and stress reactions. Furthermore, qRT–PCR analysis indicated that PbeGSs and PbeGOGATs showed differential expression under exogenous hormones (GA3, IAA, SA, ABA) and abiotic stress (NO3− and salt stress). In which, the expression of PbeGS2.2 was up–regulated under hormone treatment and down–regulated under salt stress. Furthermore, physiological experiments demonstrated that GA3 and IAA promoted GS, Fd–GOGAT, and NADH–GOGAT enzyme activities, as well as the N content. Correlation analysis revealed a significant positive relationship between PbeGS1.1, PbeGS2.2, PbeNADH–GOGATs, and the N content. Therefore, PbeGS1.1, PbeGS2.2, and PbeNADH–GOGATs could be key candidate genes for improving NUE under plant hormone and abiotic stress response. To the best of our knowledge, our study provides valuable biological information about the GS and GOGAT family in the pear for the first time and establishes a foundation for molecular breeding aimed at developing high NUE pear rootstocks.

Intraguild Predation or Spatial Separation? The efficacy and Interactions of Two Natural Enemy Species for the Biological Control of Pear Psyllid (Cacopsylla pyri)

Pear psyllid (Cacopsylla pyri) is a persistent pest to the pear industry; with an estimated cost of £5 million per annum in the UK alone. This phloem feeding insect is resistant to a large proportion of approved pesticides, necessitating the use of alternative control strategies. Many pear growers practice integrated pest management (IPM) of pear psyllid, focusing on maximizing natural enemy populations, whilst minimizing the use of agrochemical sprays. The anthocorid Anthocoris nemoralis and the European earwig Forficula auricularia are particularly effective at controlling pear psyllid populations during the summer months. Despite the effectiveness of both natural enemies, there is a lack of understanding on whether both species should be promoted together or separately, due to the risk of intraguild predation (IGP) or interference competition. Furthermore, abiotic factors including temperature may influence both behaviors, altering activity level and niche overlap. Although IGP and interference competition have been documented between multiple species of natural enemies neither have been studied between these two specific predators. Using microcosm experiments, olfactometer assays and survival analyses this study demonstrated whether A. nemoralis and F. auricularia can be used in synchrony to control pear psyllid. Results indicated that IGP is present; F. auricularia will consume A. nemoralis when predators are not spatially separate and in absence of psyllid prey. There was no evidence for interference competition, although both predators consumed more prey at higher temperatures. This confirms that pear growers can encourage both predators for the control of pear psyllid without losing predation efficacy.

Bayesian analysis of the growth of pears in the cultivate Shinseiki using non-linear models

The pear of the Pyrus genus is the third most consumed fruit in Brazil, however, internal production is low and most demand is obtained through imports. Brazil has favorable conditions for its cultivation and one of its main economic sectors is agriculture, being responsible for generating a large number of jobs and income for the country. In this sense, studies related to this fruit can provide information and encourage its production. Using non-linear models, it is possible to identify growth patterns such as fruit length and diameter, which can help determine the ideal harvest point. Therefore, the goal of this article was to compare the Logistic and Gompertz non-linear models in describing the growth curves in diameter and length of the Asian pear tree using the Bayesian approach. The results indicated the Logistic model as the best to describe these two variables and provided asymptotic averages of 70.0607 and 79.706 for length and diameter, respectively.

ОЦЕНКА ЭФФЕКТИВНОСТИ ИНСЕКТИЦИДОВ ШИРОКОГО СПЕКТРА ДЕЙСТВИЯ В КОНТРОЛЕ ГРУШЕВОЙ МЕДЯНИЦЫ

Pear psylla Psylla pyri L. it is one of the main pests of pears worldwide. Decisions on the timing of preventive treatments and the choice of plant protection products used are made on the basis of regular monitoring of the stages of phytophagan development and taking into account the specifics of the action of insecticides on a particular stage of pest development. The article analyzes the range of insecticides allowed on pear against pear psylla, which is represented by preparations from 8 chemical classes. To reduce the resistance of pear psylla to the used pesticides, it is necessary to expand the range of broad-spectrum insecticides against this phytophagan. In this study, insecticides with larvicidal action, such as Voliam Flexi, SC, Lirum, SC, Lufox, EC, were tested in laboratory conditions. The characteristics of the used pesticides are given and the mechanisms of their action are described.Samples of annual pear growth were selected in the Prikuban zone of the Zakuban horticulture subzone of the Krasnodar region, Ust-Labinsk district. As a result of the study, it was found that the following pesticides have the best biological efficacy against nymphs (first-third age) of pear psylla: Voliam Flexi, SC with a consumption rate of 0.5 l/ha and Lirum, SC 1.5 l/ha. On the seventh day, they showed a maximum biological efficacy of 100 %, which was at the level of the standard preparation Movento Energy, SC. In this experiment, Lufox, SC had low efficacy, due to the fact that the drug has a longer mechanism of action, it takes 10-12 days for a good effect. We recommend using the data obtained in the case of registration of tested preparations for the control of pear psylla.

Ceratocystis fimbriata Causing Postharvest Fruit Rot of Pear in Punjab, Pakistan.

Pear (Pyrus communis) is an important deciduous fruit cultivated on a worldwide scale including Pakistan. During August 2021, a postharvest fruit rot disease was observed on several pears at various farmers market in Okara- a district of Punjab Province, Pakistan. The incidence of the disease varied from 7 to 20% with 35% disease severity. Necrotic spots (10 to 20 mm diameter) were first observed on the infected pear fruit. The spots enlarged gradually and developed into a brown, water-soaked and rotted lesion. Eventually, the whole fruit became soft, rotted and covered with a gray-brown mycelium. The isolates were obtained from the symptomatic tissues (n = 18) incubated on carrot discs that had been surface sterilized in 100-ppm streptomycin solution. After consistent sporulation of a fungus on the carrot discs, the ascospore masses formed at the tip of perithecia were transferred to malt extract agar (MEA). Primary conidia were cylindrical and hyaline (7 to 11 × 4 to 7 μm) and secondary conidia were hyaline and barrel-shaped (7 to 12 × 5 to 8 μm). Endoconidiophores with primary conidia were (12 to 27 × 2.6 to 5.5 μm). Perithecia produced on carrot discs were dark brown to black, and the base was 157 to 278 μm in diameter. Ascomatal necks were 512 to 656 µm long, dark brown to black, lighter in color at apices, tapering from base (23 to 45 μm diameter) to apex (13 to 24 μm diameter). Ostiolar hyphae were 41 to 79 μm long. Ascospores were hyaline, hat shaped, 3 to 4 μm long, and accumulated in a sticky matrix at the tips of perithecial necks. Mycelium was initially hyaline but became dark greenish brown after 7 days. Dark brown, thick-walled aleuroconidia (13 to 19.5 × 9 to 14 μm) appeared on culture plates after 2 months. Based on morphological characteristics, the fungus was identified as Ceratocystis fimbriata (Engelbrecht, 2005; Suwandi et al. 2021). To further confirm species identification, genomic DNA of two representative isolates (UO-05 and UO-06) was obtained using an extraction kit. The internal transcribed spacer (ITS) region was amplified using ITS1/4 (White et al. 1990). A BLAST search with GenBank accession nos. OR185451 and OR185456 indicated 99 to 100% identity with several C. fimbriata including type species (MH856050.1; KC493160.1; MT560374.1). Pathogenicity tests were conducted by inoculating nine disease-free pear (cv. Concord) fruit after disinfesting in 75% ethanol. A prepared spore suspension (1.0 × 106 spores/ml) was dropped on the wounds (a depth of 1 mm diameter) on the pear surface, which were made by a sterilized needle. 10 μl of a prepared spore suspension was dropped onto nine pears. Sterile water (10 μl) was dropped on the wounded sites of nine pear fruits as negative controls and all fruits were incubated in a growth chamber at 30/26°C (day/night, 90% relative humidity). Symptoms similar to those on the naturally infected fruits began after 4 to 5 days of inoculation, while controls remained healthy. The fungal isolates recovered from inoculated pears were morphologically identical to the C. fimbriata isolates originally recovered from symptomatic fruits fulfilling Koch's postulates. The pathogen has been reported to cause postharvest fruit rot of passion fruit and cucumber (Firmino et al. 2016; Li et al. 2019). To our knowledge, this is the first report of C. fimbriata causing fruit rot of pear in Punjab Province. The detection of this disease will help pear growers to take actions to monitor and prevent disease outbreak as well as develop an effective management practice when it occurs.

Evaluation of Plant Defense Inducers and Plant Growth Regulators for Fire Blight Management Using Transcriptome Studies and Field Assessments.

Fire blight, caused by Erwinia amylovora, is a destructive disease of pome fruit trees. In the United States, apple and pear growers rely on applications of copper and antibiotics during bloom to control fire blight, but such methods have already led to regional instances of resistance. In this study, we used transcriptome analyses and field trials to evaluate the effectiveness of three commercially available plant defense elicitors and one plant growth regulator for fire blight management. Our data indicated that foliar applications of acibenzolar-S-methyl (ASM; Actigard 50WG) triggered a strong defense-related response in apple leaves, whereas applications of Bacillus mycoides isolate J (LifeGard WG) or Reynoutria sachalinensis extract (Regalia) did not. Genes upregulated by ASM were enriched in the biological processes associated with plant immunity, such as defense response and protein phosphorylation. The expression of several pathogenesis-related (PR) genes was induced by ASM as well. Surprisingly, many differentially expressed genes in ASM-treated apple leaves overlapped with those induced by treatment with prohexadione-calcium (ProCa; Apogee), a plant growth regulator that suppresses shoot elongation. Further analysis suggested that ProCa likely acts similarly to ASM to stimulate plant immunity because genes involved in plant defense were shared and significantly upregulated (more than twofold) by both treatments. Our field trials agreed with the transcriptome study, demonstrating that ASM and ProCa exhibit the best control performance relative to the other biopesticides. Taken together, these data are pivotal for the understanding of plant response and shed light on future improvements of strategies for fire blight management.

Arthrobacter sp. Inoculation Improves Cactus Pear Growth, Quality of Fruits, and Nutraceutical Properties of Cladodes

A study was undertaken to determine the effects of a strain of Arthrobacter sp., a Plant Growth-Promoting Bacteria (PGPB), on plant phenology and qualitative composition of Opuntia ficus-indica (L.) Mill. fruits and cladodes. The strain was inoculated in soil, and its effects on cactus pear plants were detected and compared to nontreated plants. Compared to the latter, the treatment with bacteria promoted an earlier plant sprouting (2 months before the control) and fruitification, ameliorating fruit quality (i.e., improved fresh and dry weight: + 24% and + 26%, respectively, increased total solid content by 30% and polyphenols concentrations by 22%). The quality and quantity of monosaccharides of cladodes were also increased by Arthrobacter sp. with a positive effect on their nutraceutical value. In summer, the mean values of xylose, arabinose, and mannose were significantly higher in treated compared to not treated plants (+ 3.54; + 7.04; + 4.76 mg/kg d.w. respectively). A similar trend was observed in autumn, when the cladodes of inoculated plants had higher contents, i.e., 33% xylose, 65% arabinose, and 40% mannose, respect to the controls. In conclusion, Arthrobacter sp. plays a role in the improvement of nutritional and nutraceutical properties of cactus pear plants due to its capabilities to promote plant growth. Therefore, these results open new perspectives in PGPB application in the agro-farming system as alternative strategy to improve cactus pear growth, yield, and cladodes quality, being the latter the main by-product to be utilized for additional industrial uses.

The Nondestructive Model of Near-Infrared Spectroscopy with Different Pretreatment Transformation for Predicting “Dangshan” Pear Woolliness Disease

The “Dangshan” pear woolliness response is a physiological disease that mostly occurs in the pear growth process. The appearance of the disease is not obvious, and it is difficult to detect with the naked eye. Therefore, finding a way to quickly and nondestructively identify “Dangshan” pear woolliness disease is of great significance. In this paper, the near-infrared spectral (NIR) data of “Dangshan” pear samples were collected at 900–1700 nm reflectance spectra using a handheld miniature NIR spectrometer, and the data were modelled and analysed using random forest (RF), support vector machine (SVM) and boosting algorithms under the processing of 24 pretreatment methods. Considering the variations between different pretreatment methods, this work determined the relative optimality index of different pretreatment methods by evaluating their effects on model accuracy and Kappa and selected the best-performing first derivative with standard normal variate and Savitzky–Golay and first derivative with multiplicative scatter correction and Savitzky–Golay as the best pretreatment methods. With the best pretreatment method, all five models in the three categories showed good accuracy and stability after parameter debugging, with accuracy and F1 greater than 0.8 and Kappa floating at approximately 0.7, reflecting the good classification ability of the models and proving that near-infrared spectroscopy (NIRS) in the rapid identification of “Dangshan” pear woolliness response disease was feasible. By comparing the performance differences of the models before and after the pretreatment methods, it was found that the ensemble-learning models such as RF and boosting were more stringent on pretreatment methods in identifying “Dangshan” pear woolliness response disease than support vector machines, and the performance of the ensemble learning models was significantly improved under appropriate pretreatment methods. This experiment provided a relatively stable detection method for “Dangshan” pear woolliness response disease under nonideal detection conditions by analysing the impact of pretreatment methods and models on the prediction result.

Comprehensive Metabolomic and Transcriptomic Analysis of the Regulatory Network of Volatile Terpenoid Formation during the Growth and Development of Pears (Pyrus spp. ‘Panguxiang’)

Volatiles are essential substances that determine distinct fruit flavors and user preferences. However, the metabolic dynamic and molecular modulation models that regulate the overall flavor generation during fruit growth and ripening are still largely unclear for most fruit species. To comprehensively analyze the molecular mechanism and regulation mechanism of aroma accumulation and aroma component formation in Pyrus spp. ‘Panguxiang’ (‘Panguxiang’pear), this study compared pear phenotype, sugars, organic acid content, and the expression of related genes and metabolites amid pear growth and development in Pyrus spp. ‘Panguxiang’. A total of 417 VOCs (4 amines, 19 aromatics, 29 aldehydes, 31 alcohols, 38 ketones, 64 heterocyclic compounds, 89 terpenoids, 94 esters, and 49 others) were found. The potential gene expression patterns were explored by combining transcriptomics and metabolomics, and VOC-associated metabolism and transcriptome data from all samples were integrated during the growth and development period. On this basis, we constructed a colorful model depicting changes in the VOCs and genes throughout pear growth and development. Our findings reveal that terpenoid biosynthesis pathways are the main aroma production pathways during pear growth and development. In addition to providing novel insights into the metabolic control of fruit flavor during growth and development, this study also provides a new theoretical basis for studying aroma metabolites in pears.

YOLOv5s-FP: A Novel Method for In-Field Pear Detection Using a Transformer Encoder and Multi-Scale Collaboration Perception.

Precise pear detection and recognition is an essential step toward modernizing orchard management. However, due to the ubiquitous occlusion in orchards and various locations of image acquisition, the pears in the acquired images may be quite small and occluded, causing high false detection and object loss rate. In this paper, a multi-scale collaborative perception network YOLOv5s-FP (Fusion and Perception) was proposed for pear detection, which coupled local and global features. Specifically, a pear dataset with a high proportion of small and occluded pears was proposed, comprising 3680 images acquired with cameras mounted on a ground tripod and a UAV platform. The cross-stage partial (CSP) module was optimized to extract global features through a transformer encoder, which was then fused with local features by an attentional feature fusion mechanism. Subsequently, a modified path aggregation network oriented to collaboration perception of multi-scale features was proposed by incorporating a transformer encoder, the optimized CSP, and new skip connections. The quantitative results of utilizing the YOLOv5s-FP for pear detection were compared with other typical object detection networks of the YOLO series, recording the highest average precision of 96.12% with less detection time and computational cost. In qualitative experiments, the proposed network achieved superior visual performance with stronger robustness to the changes in occlusion and illumination conditions, particularly providing the ability to detect pears with different sizes in highly dense, overlapping environments and non-normal illumination areas. Therefore, the proposed YOLOv5s-FP network was practicable for detecting in-field pears in a real-time and accurate way, which could be an advantageous component of the technology for monitoring pear growth status and implementing automated harvesting in unmanned orchards.

The Δ1-pyrroline-5-carboxylate synthetase family performs diverse physiological functions in stress responses in pear (Pyrus betulifolia).

Δ1-Pyrroline-5-carboxylate synthetase (P5CS) acts as the rate-limiting enzyme in the biosynthesis of proline in plants. Although P5CS plays an essential role in plant responses to environmental stresses, its biological functions remain largely unclear in pear (Pyrus betulifolia). In the present study, 11 putative pear P5CSs (PbP5CSs) were identified by comprehensive bioinformatics analysis and classified into five subfamilies. Segmental and tandem duplications contributed to the expansion and evolution of the PbP5CS gene family. Various cis-acting elements associated with plant development, hormone responses, and/or stress responses were identified in the promoters of PbP5CS genes. To investigate the regulatory roles of PbP5CS genes in response to abiotic and biotic stresses, gene expression patterns in publicly available data were explored. The tissue-specific expressional dynamics of PbP5CS genes indicate potentially important roles in pear growth and development. Their spatiotemporal expression patterns suggest key functions in multiple environmental stress responses. Transcriptome and real-time quantitative PCR analyses revealed that most PbP5CS genes exhibited distinct expression patterns in response to drought, waterlogging, salinity-alkalinity, heat, cold, and infection by Alternaria alternate and Gymnosporangium haraeanum. The results provide insight into the versatile functions of the PbP5CS gene family in stress responses. The findings may assist further exploration of the physiological functions of PbP5CS genes for the development and enhancement of stress tolerance in pear and other fruits.

PbHCT4 regulates growth through affecting chlorogenic acid (CGA) content in pear

• The chlorogenic acid contents between dwarf and standard pear trees were different significantly. • Low concentration of chlorogenic acid promoted the growth of pear, while high concentration of chlorogenic acid inhibited the growth. • PbHCT4 gene changed plant height by regulating chlorogenic acid content and auxin transport. Due to its many advantages, dwarfing and dense planting is an important mode of modern fruit tree cultivation. Phenols have been reported to play various roles in the growth regulation of plants. Here, to verify the correlation between chlorogenic acid (CGA) and the growth of pear trees, the CGA content of standard and dwarf pear trees as well as the effect of exogenous CGA upon their growth, were investigated and analyzed. Our results showed that the CGA content of two dwarf-type varieties, ‘Zhongai 1′ (Z1) and ‘PY-9′ was significantly higher than that of two standard-type Pyrus betulaefolia (P1 and P2). Whereas a low concentration of CGA accelerated pear tree growth, and a high concentration of CGA could inhibit it. Then, through an expression pattern analysis of four CGA synthesis-related genes, PbHCT1–4 , we found that the dwarf phenotype might be related to the expression levels of PbHCTs , especially to those of PbHCT2–4 in shoots. Of these, PbHCT4 was selected as a candidate gene and transformed into tobacco. When compared with control tobacco plants, the transgenic plants attained taller heights and had a greater CGA content, as well as increased expression levels of the auxin efflux carrier gene, NbPIN. Accordingly, we speculate the PbHCT4 gene promotes the synthesis of CGA, which influences plant growth by mediating auxin's transport in pear trees. These findings are helpful for advancing analysis of dwarf mechanism, which is critical for the breeding of new dwarf pear varieties.

Risk aversion, marketing outlets, and biological control practice adoption: insight from pear farmers in China.

Biological control (BC) is an important component of green control techniques, and its adoption in the production of fresh produce holds economic and ecological importance as an alternative to chemical pesticides, yet its current adoption rate is not high. To clarify the issue, this study analyzes the factors that influence growers' adoption of BC practices in China's orchard systems. We focus on how marketing outlets and risk attitudes affect farmers' adoption of BC practices. A field survey of 327 pear growers was conducted in three main pear-producing areas of Hebei, Shandong, and Hubei provinces of China between October and December 2020. Results show that farmers' risk aversion has a significant and negative impact on their adoption of BC practices. The market environment is another dramatic factor affecting farmers' adoption. Both green certification and cooperative marketing have a significant role in promoting farmers' adoption of BC practices. Our findings highlight the importance of risk reduction and market environment to BC adoption. Furthermore, it can provide critical information for policymakers in formulating strategies to promote the application and extension of BC practices among farmers in developing countries, such as China.

On-Farm Supplemental Irrigation of ‘Roja Lisa’ Cactus Pear: Pre- and Postharvest Effects

Opuntia species grow in arid and semiarid lands, where water for irrigation is scarce. However, supplemental irrigation can be a feasible strategy for commercial cactus pear orchards. From 2018 to 2020, a commercial cactus pear orchard was managed to validate the effect of supplemental irrigation on fruit yield, crop water use efficiency, fruit quality, and storability of ‘Roja Lisa’ cactus pear grown in the semiarid region of Mexico. The irrigation treatments were no irrigation and supplemental irrigation, with four replications. Crop water use was less and, therefore, water productivity greater in non-irrigated plants than in plants with supplemental irrigation. Mean fruit yield, mean fruit mass, and proportion of commercial fruit increased with supplemental irrigation. These differences were more pronounced in growing seasons with less rainfall. Fruit quality at harvest or after room temperature or cold storage was examined. Fruit mass loss rate was reduced in fruit receiving supplemental irrigation in both storage conditions. In addition, supplemental irrigation was consistent with water savings and food security programs in marginal areas: this irrigation strategy improved both pre- and postharvest some quality components of cactus pear fruit. Therefore, this irrigation strategy is suggested for cactus pear growers, depending on the availability of water for irrigation.

Awareness and adoption level of improved practices by pear growers of Tarn Taran district

Pear is one of the most important fruit crops of the temperate region. In Punjab, a low chill variety Patharnakh, has been widely cultivated and become the commercial fruit crop. The present investigation was conducted to assess the awareness and adoption of recommended pear production practices to narrow the adoption gaps so as to achieve sustainable production of quality fruits in Tarn Taran District to evaluate the effect of different technology variables on the awareness score and adoption level of recommended package of practices for pear. The study showed that the respondents along with awareness adopted some of the recommended practices for pear cultivation on priority such as timely irrigation to the plants (As = 1.0; Al =2.6), use of FYM along with chemical fertilizers and timely pruning and training of the fruit plants having good awareness and adoption values. However, they were moderate in terms of weed management (As = 0.58; Al =1.26) and practice of proper packaging and marketing of fruits (As = 0.56; Al =1.20). On the other side, management of mite (As = 0.06; Al =0.10) followed by use of micronutrients as balanced nutrition (As = 0.10; Al =0.22), use of Bordeaux mixture for sap wood and root rot and use of potassium nitrate (KNO3) for better yield were practices with least awareness and adoption values. The results indicated that, a mere awareness of technology does not lead to adoption. This gap can be bridged by imparting practical know-how with hands-on training to pear growers in niche area.

DMI-Fungicide Resistance in Venturia nashicola, the Causal Agent of Asian Pear Scab-How Reliable Are Mycelial Growth Tests in Culture?

Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears and control of this disease largely relies on sterol demethylation inhibitor (DMI) fungicides. However, pear growers have complained about field performance of DMIs since the mid-2000s. In this study, to evaluate pathogen sensitivity, mycelial growth tests and inoculation tests were conducted using DMI-amended culture medium and fungicide-sprayed potted pear trees, respectively. Results confirmed distribution of isolates resistant to fenarimol, hexaconazole, and difenoconazole in the field populations. Importantly, results from tests in culture did not fully correlate with those from tests in planta. Due to phenotypic instability of resistance and poor sporulation of this pathogen in culture, resistance is generally assessed by laborious and time-consuming inoculation with conidia collected from a field. To improve the result interpretation from in vitro tests, the isolates were genotyped: the CYP51 gene which encodes the target sterol 14α-demethylase was sequenced and various mutations have been detected in the coding sequence of DMI-resistant isolates. In addition to the detected single nucleotide polymorphisms, alternative mechanisms, not based on changes in the structure of the target protein, may also increase DMI resistance. Development of molecular methods for the diagnosis of DMI resistance seems to be challenging in V. nashicola.

The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of Pear Stem CuPear Stem Cutting

The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of The Effect of Different Levels of Indole-3-butyric Acid (IBA) and Naphthaleneacetic acid (NAA) on the Rooting of Pear Stem CuPear Stem Cutting

PbSRT1 and PbSRT2 regulate pear growth and ripening yet displaying a species-specific regulation in comparison to other Rosaceae spp.

Epigenetic regulation is crucial to ensure a coordinated control of the different events that occur during fruit development and ripening. Sirtuins are NAD+-dependent histone deacetylases involved in the regulation of gene expression of many biological processes. However, their implications in the Rosaceae family remains unexplored. Accordingly, in this work, we demonstrated the phylogenetic divergence of both sirtuins among Rosaceae species. We then characterized the expression pattern of both SRT1 and SRT2 in selected pome and stone fruit species. Both SRT1 and SRT2 significantly changed during the fruit development and ripening of apple, nectarine and pear fruit, displaying a different expression profile. Such differences could explain in part their different ripening behaviour. To further unravel the role of sirtuins on the fruit development and ripening processes, a deeper analysis was performed using pear as a fruit model. In pear, PbSRT1 gene expression levels were negatively correlated with specific hormones (i.e. abscisic acid, indole-3-acetic acid, gibberellin A1 and zeatin) during the first phases of fruit development. PbSRT2 seemed to directly mediate pear ripening in an ethylene-independent manner. This hypothesis was further reinforced by treating the fruit with the ethylene inhibitor 1-methylcyclopropene (1-MCP). Instead, enhanced PbSRT2 along pear growth/ripening positively correlated with the accumulation of major sugars (R2 > 0.94), reinforcing the idea that sugar metabolism may be a target of epigenetic modifications during fruit ripening. Overall, the results from this study point out, for the first time, the importance that sirtuins have in the regulation of fruit growth and ripening of pear fruit by likely regulating hormonal and sugar metabolism.

The Effects of Different Rootstocks on the Graft Success and Stion Development of Some Pear Cultivars

ABSTRACT In modern pear growing, quince and pear clonal rootstocks are used instead of pear seedlings. This study aimed to evaluate the effect of different quince and pear rootstocks on the graft success and the stion (scion+rootstock) growth performance of some pear cultivars/genotypes. In the study, quince (Quince BA 29, Quince A and Quince MC), pear (OHxF 333, Fox 11, Farold 40) clones and pear seedlings were grafted in two standard (Deveci and Williams) and 11 local (‘Bardak,’ ‘Dalkıran,’ ‘Eşek,’ ‘İstanbul,’ ‘Kara,’ ‘Karga,’ ‘Karpuz,’ ‘Kış,’ ‘Sarıkum,’ ‘Tefenc’ and ‘Yaz Ziraati’) promising pear cultivars were used. Significant differences were observed in both rootstocks and varieties in terms of graft success and plant development in the study. The graft take, sprout and survival ratios were higher in pear rootstocks than in the quince rootstocks. While the highest graft survival ratio was observed in Fox 11, the lowest was in the BA 29 quince rootstock. The highest graft sprout and graft survival ratio were in ‘Deveci,’ the lowest in ‘Williams,’ ‘Bardak’ and ‘Kış’ varieties. While the highest shoot lengths and highest diameters were detected in the pear seedling, the lowest were in the MC rootstock. While the longest shoots were observed in ‘Kara,’ the thickest shoots were observed in ‘Eşek’ genotypes. As a result of this study, it was determined that the 13 pear cultivars/genotypes grafted on different rootstocks were sufficient in terms of graft success and stion growth performances and it was found that stion of sufficient quality could be grown in the field condition.

Life Cycle Assessment of Variable Rate Fertilizer Application in a Pear Orchard

Precision Agriculture (PA) is a crop site-specific management system that aims for sustainability, adopting agricultural practices more friendly to the environment, like the variable rate application (VRA) technique. Many studies have dealt with the effectiveness of VRA to reduce nitrogen (N) fertilizer, while achieving increased profit and productivity. However, only limited attention was given to VRA’s environmental impact. In this study an International Organization for Standardization (ISO) based Life Cycle Assessment (LCA) performed to identify the environmental effects of N VRA on a small pear orchard, compared to the conventional uniform application. A Cradle to Gate system with a functional unit (FU) of 1 kg of pears was analyzed including high quality primary data of two productive years, including also the non-productive years, as well as all the emissions during pear growing and the supply chains of all inputs, projecting them to the lifespan of the orchard. A methodology was adopted, modelling individual years and averaging over the orchard’s lifetime. Results showed that Climate change, Water scarcity, Fossil fuels and Particulate formation were the most contributing impact categories to the overall environmental impact of the pear orchard lifespan, where climate change and particulates were largely determined by CO2, N2O, and NH3 emissions to the air from fertilizer production and application, and as CO2 from tractor use. Concerning fertilization practice, when VRA was combined with a high yield year, this resulted in significantly reduced environmental impact. LCA evaluating an alternative fertilizer management system in a Greek pear orchard revealed the environmental impact reduction potential of that system.