Tree shape can affect microclimate, which may directly influence fruit growth and development. Open center and round head are two tree canopy shapes that are generally used in Camellia oleifera Abel. cultivation. To study the effects of the two canopy shapes on the microclimate and fruit quality parameters inside the canopy and investigate the correlations between microclimate and oil yield characteristics, microclimates in different developmental periods and fruit quality parameters at maturity at different positions in the two canopy shapes were determined. In this study, the open-center shape increased the light intensity and temperature, and reduced the relative humidity within the canopy, and the microclimate was more uniformly distributed within the open-center canopy. Fruit quality parameters of open-center canopied trees were also significantly increased and had more uniform distributions, especially the oil yield parameters. The content ratio of the dry seed, oil content ratio of the fresh fruit, and oil yield increased by 43.55%, 59.30% and 79.01%, in the lower layer, respectively, and 27.33%, 41.75%, and 55.43%, in the inner canopy, respectively, compared to those of round-head canopied trees. For both canopy shapes, oil yield parameters had positive correlations with light intensity and temperature, but negative correlations with relative humidity, and the correlation coefficients between light intensity and temperature at different developmental stages and oil yield parameters in round-head canopies were greater than in the open-center canopies. Additionally, regression equations between the single microclimatic factor in different developmental periods and oil yield parameters could be used to estimate the latter in the two canopy shapes. The optimum light conditions for open-center and round-head canopy shapes were 916–1893 and 1108–1259 μmol·m²·s⁻¹, respectively. Overall, the open-center canopy had a more desirable microclimate and a more uniform microclimate distribution, especially the light intensity, which contributes to high uniform fruit quality parameters. Thus, an open-center canopy is the desirable shape in C. oleifera production.

Introduction: Phytohormones play a crucial role in regulating the abscission of plant organs and tissues.Methods: In this study, the ultrastructure of the sepals of Korla fragrant pears was observed using a transmission electron microscope, and high-performance liquid and gas chromatography were used to analyze the dynamic changes of phytohormones in the abscission zone during the calyx abscission process of Korla fragrant pears, and mass spectrometry imaging was applied to ascertain the spatial distribution of phytohormones.Results: The results revealed that the mitochondria in the abscission zone of the decalyx fruits were regularly distributed around the cell wall, and the chloroplasts were moderately present. In contrast, in the persistent calyx fruit, the corresponding parts of the abscission zone showed a scattered distribution of mitochondria within the cells, and there was a higher number of chloroplasts, which also contained starch granules inside. Mass spectrometry imaging revealed that ABA was enriched in the abscission zone of the decalyx fruit, and their ionic signal intensities were significantly stronger than those of the persistent calyx fruit. However, the ionic signal intensities of Indole-3-acetic acid (IAA) and Gibberellin A3 (GA₃) of the persistent calyx fruit were significantly stronger than those in the abscission zone of the decalyx fruit and were concentrated in the persistent calyx fruit. 1-Aminocyclopropanecarboxylic Acid (ACC) did not show distinct regional distribution in both the decalyx and persistent calyx fruits. Furthermore, before the formation of the abscission zone, the levels of IAA, GA₃, and zeatin (ZT) in the abscission zone of the decalyx fruits were significantly lower than those in the persistent calyx fruits by 37.9%, 57.7%, and 33.0%, respectively, while the levels of abscisic acid (ABA) and ethylene (ETH) were significantly higher by 21.9% and 25.0%, respectively. During the formation of the abscission zone, the levels of IAA, GA₃, and ZT in the abscission zone of the decalyx fruits were significantly lower than those in the persistent calyx fruits by 41.7%, 71.7%, and 24.6%, respectively, while the levels of ABA and ETH were significantly higher by 15.2% and 80.0%, respectively. After the formation of the abscission zone, the levels of IAA and GA₃ in the abscission zone of the decalyx fruits were lower than those in the persistent calyx fruits by 20.8% and 47.8%, respectively, while the levels of ABA and ETH were higher by 271.8% and 26.9%, respectively. In summary, during the calyx abscission process of Korla fragrant pears, IAA and GA₃ in the abscission zone inhibited abscission, while ABA and ETH promoted calyx abscission. These research findings enrich the understanding of the regulatory mechanism of plant hormones on calyx abscission and provide a theoretical basis for the study of exogenous plant growth regulators for regulating calyx abscission in Korla fragrant pear.

There are considerable differences in chestnut yield and quality across different chestnut-producing regions in China, indicating that environmental factors affect these properties of chestnuts. Furthermore, nut yield and quality differ depending on canopy position. Therefore, this study investigated the relationship between the canopy microclimate, nut yield, and quality. We determined microclimate factors from blossoming to ripening at different positions in the canopy. Nut yield and quality and the number of different branch types were measured at various canopy positions. The light intensity and temperature of the different canopy layers exhibited funnel-form distributions ranging from 0 to 3600 μmol·m²·s⁻¹ and from 32 to 37 °C, respectively. Canopy humidity showed an inverted funnel-shaped distribution ranging from 26% to 40%. Nut yield and quality in the top and outer canopies were higher than in the bottom and inner canopies. Branches in the top-middle and peripheral parts of the canopy also produced higher yields, especially strong branches that bore more nuts. Nut yield and quality had positive correlations with light intensity (r = 0.735) and temperature (r = 0.709), whereas they were inversely associated with humidity (r = −0.584). The nut yield was more than 200 gm⁻³ when the light intensity was above 1500 μmol·m²·s⁻¹, the temperature was above 34.4 °C, and the humidity was below 27.5%.

Fire blight, caused by Erwinia amylovora, is a devastating bacterial disease threatening apple, pear, and other Rosaceae species. In our prior study, transcriptome analysis identified a fire blight-resistant variety, Duli (Pyrus betulifolia Bunge), and highlighted the PR1 gene as a key resistance factor. Using Duli’s genomic data, we systematically identified and characterized the Pb-PR-1 gene family through bioinformatics analysis. A total of 31 Pb-PR-1 genes were found, encoding proteins of 123–341 amino acids. Phylogenetic analysis grouped these genes into four subfamilies, with 27 genes distributed across seven chromosomes, all contain a conserved CAP superfamily domain. Their promoter regions were enriched in hormone and stress-responsive elements. After inoculation with E. amylovora, susceptible Duli showed lesion development by day 2, with rapid disease progression, while resistant plants exhibited slower disease advancement and smaller lesions. Enzyme activity assays revealed that in resistant plants, PPO (polyphenol oxidase) and CAT (catalase) activities peaked on day 6, showing a 2.4-fold and 3.81-fold increase compared to susceptible Duli. At the same time, MDA (malondialdehyde) content decreased by 16.6%. The activities of SOD (superoxide dismutase) and PAL (phenylalanine ammonia-lyase) peaked on day 4, with increments of 34.32% and 47.1% over susceptible Duli. qRT-PCR showed significant differences in Pb-PR-1 gene family expression between resistant and susceptible plants post-inoculation. Notably, Pb-PR-1-11, Pb-PR-1-21, and Pb-PR-1-26 expression increased with infection duration, aligning with PPO and CAT activity trends. Other genes showed high early infection expression but declined by day 6. Pb-PR-1-3, Pb-PR-1-6, Pb-PR-1-8, Pb-PR-1-16, and Pb-PR-1-30 were upregulated 13.17-fold on average by day 2. In summary, the Pb-PR-1 family exhibited elevated expression during early infection and enhanced defense-related enzyme activities, improving plant resistance. This study provides a foundation for understanding the PR-1 family’s role in Duli and advancing fire blight resistance in Pyrus species.

Programmed cell death (PCD) is common in plant growth and development, such as xylem development, organ senescence, and abscission. Calyx abscission in Korla fragrant pear contributes to fruit quality, while it was not clear whether PCD occurred during calyx abscission and which signals regulated the process. Therefore, it is imperative to clarify the process of PCD in the process of calyx abscission in Korla fragrant pear under natural conditions to enrich the mechanism of calyx abscission. The results showed that the total time of calyx abscission of Korla fragrant pear began from 6 days after pollination (DAP) to 13 DAP, and the peak of calyx abscission occurred 10 DAP. During the whole process of calyx abscission, PCD started 6 DAP. At 9 DAP, the degree of PCD deepened. At 12 DAP, the cells in the abscission zone showed asymmetry on both sides, the organelles in the distal cells of the abscission zone degraded into apoptotic fragments, and the protective layer of the normal development of cells located at the proximal end of the abscission zone region ended the PCD process. ETH concentrations in the abscission zone of the decalyx fruit were significantly higher than those of the persistent calyx fruits in each period during calyx abscission, and high levels of ethylene and hydrogen peroxide and low contents of the GA₃, ZT, and hydroxyl radicals promoted calyx abscission before the formation of the abscission zone. At 3 DAP, the ethylene concentration (43.97 ppm) and H₂O₂ content (8.49 μmol/g) of decalyx fruit in the abscission zone were significantly higher than those of persistent calyx fruit by 67.69% and 27.86%, respectively; however, the GA₃, ZT, and hydroxyl radicals showed the opposite. Overall, PCD in the abscission zone of decalyx fruits did occur during the calyx abscission of Korla fragrant pear, and ethylene and H₂O₂ might play major roles in initiating the PCD process during Korla fragrant pear calyx abscission.

Fire blight, caused by Erwinia amylovora, poses a significant threat to the sustainable development of the Korla Xiangli (Pyrus×sinkiangensis. Yu) industry. In this study, we used multiple experimental approaches to comprehensively evaluate the efficacy of three antagonistic bacterial strains—namely, Mg-7 (Leuconostoc mesenteroides), Rt-10 (Alcaligenes faecalis), and Rt-11 (Bacillus siamensis)—in controlling fire blight. In vitro plate inhibition assays revealed that Mg-7 exhibited the largest inhibition zone diameter, exceeding Rt-10 and Rt-11 in this respect, suggesting its strong antifungal potential. In therapeutic tests conducted on detached leaves, Mg-7 achieved the highest control efficiency, 60.39%, while Rt-10 demonstrated the greatest efficiency (76.96%) in protective tests. Conversely, in therapeutic trials focusing on detached branches, Mg-7 showed a control efficiency of 45.90%, whereas Rt-11 exhibited the highest efficiency, 86.27%, in protective trials. Furthermore, in vitro evaluations indicated that the Mg-7 treatment significantly reduced the lesion spread area. Enzymatic analyses revealed that, in the leaf protection assay, catalase activity (CAT) demonstrated significant increases of 65.56%, 85.46%, and 45.55% under the Mg-7, RT-10, and RT-11 treatments, respectively, when compared with the EA control group on day four. Correspondingly, in the branch protection assay, polyphenol oxidase (PPO) activity displayed marked elevations of 62.84%, 52.06%, and 82.69% under identical experimental conditions at the same time point. These treatments not only upregulated antioxidant enzyme activities but also significantly reduced malondialdehyde (MDA) content, effectively mitigating oxidative damage while enhancing foliar and branch resistance to fire blight infection. Field trials conducted in outdoor orchards confirmed that the Mg-7 bacterial suspension provided more effective and stable control against fire blight than Rt-10 and Rt-11. Overall, Mg-7 shows significant potential for use as a biocontrol agent for managing fire blight because of its high efficacy, stability, and ability to enhance plant defense responses.