Production Of Chinese Cabbage Research Articles

Enhancing sustainable Chinese cabbage production: a comparative analysis of multispectral image instance segmentation techniques

Accurate instance segmentation of individual crops is crucial for field management and crop monitoring in smart agriculture. To address the limitations of traditional remote sensing methods in individual crop analysis, this study proposes a novel instance segmentation approach combining UAVs with the YOLOv8-Seg model. The YOLOv8-Seg model supports independent segmentation masks and detection at different scales, utilizing Path Aggregation Feature Pyramid Networks (PAFPN) for multi-scale feature integration and optimizing sample matching through the Task-Aligned Assigner. We collected multispectral data of Chinese cabbage using UAVs and constructed a high-quality dataset via semi-automatic annotation with the Segment Anything Model (SAM). Using mAP as the evaluation metric, we compared YOLO series algorithms with other mainstream instance segmentation methods and analyzed model performance under different spectral band combinations and spatial resolutions. The results show that YOLOv8-Seg achieved 86.3% mAP under the RGB band and maintained high segmentation accuracy at lower spatial resolutions (1.33 ~ 1.14 cm/pixel), successfully extracting key metrics such as cabbage count and average leaf area. These findings highlight the potential of integrating UAV technology with advanced segmentation models for individual crop monitoring, supporting precision agriculture applications.

Effects of the Application of Organic Fertilizers on the Yield, Quality, and Soil Properties of Open-Field Chinese Cabbage (Brassica rapa spp. pekinensis) in China: A Meta-Analysis

With the development of sustainable agriculture, trials on the benefits of the application of organic fertilizers around the world have been conducted. Herein, we investigated the impact of the pure chemical fertilizers (CFs) combined with organic fertilizers compared with the application of CFs (100% CFs) and no fertilizers (NFs) on soil properties as well as the yield and quality of Chinese cabbage through meta-analysis. Results indicate that: (1) Compared with NFs, the application of organic fertilizers can significantly improve the yield and quality of Chinese cabbage and increase soil nutrients. (2) Compared with CFs, the application of organic fertilizers can increase the fresh weight, number of leaves, transverse diameter, leaf length, and development of Chinese cabbage per plant, with increases of 8.54%, 6.6%, 9.905%, 8.42%, and 10.03%; Meanwhile, organic fertilizers can significantly increase the yield (total amount of above-ground parts produced) and commercial yield (the portion that meets the required quality standards and is intended for sale) of Chinese cabbage to increase the yield and commercial yield by 10.08% and 35.56%, respectively. However, it has no significant impact on the income from growing Chinese cabbage. (3) Compared with CFs, the application of organic fertilizers can significantly increase the content of vitamin C (11.06%), soluble sugar (19.16%), and soluble protein (8.83%) and reduce the content of nitrate and nitrite in Chinese cabbage, with a reduction of up to 19.02% and 20.9%, respectively. The application of organic fertilizers will also have a certain impact on the absorption of heavy metals in Chinese cabbage. (4) Compared with CFs, the application of organic fertilizers can significantly improve soil organic matter, soil carbon sequestration, nitrogen absorption, and potassium absorption, showing increases of 12.73%, 13.19%, 7.91%, and 7.37%, and the application of organic fertilizers reduces soil electrical conductivity and available nitrogen, showing decreases of 36.78% and 38.75%, respectively. (5) The application of organic fertilizers significantly increased the content of soil urease and soil sucrase, increasing by 9.42% and 17.16%, respectively. This study helps inform the application of organic fertilizers in Chinese cabbage production.

Consumer liking of steamed green Chinese cabbage (Brassica rapa ssp. chinensis) cultivated in formulated vegetable waste-based organic hydroponic solutions

Chinese cabbage or pak choy (Brassica rapa ssp. chinensis) is often consumed because of its high nutritional content and several health advantages. Due to their promotion as being healthier and more ecologically friendly, hydroponic vegetables have seen a recent spike in consumer interest. The production of Chinese cabbage involved the processing of the vegetable waste to create various hydroponic solution formulations (F1 = banana peels, eggshells, and bean sprouts; F2 = banana humps, onion peels, bean sprouts, and moringa leaves; F3 = moringa leaves, onion peels, and bean sprouts; and F4 = AB Mix solution). They were applied at concentrations of 600, 900, 1,200, and 1,500 parts per million. The aim of this study was to investigate the relationship between the type of hydroponic growth solutions and Chinese cabbage customer acceptance. As a result, using a hedonic test of consumer liking, a panel of 32 untrained individuals was asked to show their liking score on sensory attributes of Chinese cabbage. There was a significant difference in the color liking of Chinese cabbage as an effect of hydroponic solution formulation. However, both organic vegetable waste-based formulations did not statistically substantially affect consumer acceptance, which includes color, taste, flavor, texture, and overall liking. Ultimately, vegetable waste-based organic formulations can be used to produce Chinese cabbage that is as acceptable to customers as those prepared with inorganic AB-Mix solution.

Comparative Metagenomic Analysis Reveals Rhizosphere Microbiome Assembly and Functional Adaptation Changes Caused by Clubroot Disease in Chinese Cabbage.

Clubroot is a major disease and severe threat to Chinese cabbage, and it is caused by the pathogen Plasmodiophora brassicae Woron. This pathogen is an obligate biotrophic protist and can persist in soil in the form of resting spores for more than 18 years, which can easily be transmitted through a number of agents, resulting in significant economic losses to global Chinese cabbage production. Rhizosphere microbiomes play fundamental roles in the occurrence and development of plant diseases. The changes in the rhizosphere microorganisms could reveal the severity of plant diseases and provide the basis for their control. Here, we studied the rhizosphere microbiota after clubroot disease infections with different severities by employing metagenomic sequencing, with the aim of exploring the relationships between plant health, rhizosphere microbial communities, and soil environments; then, we identified potential biomarker microbes of clubroot disease. The results showed that clubroot disease severity significantly affected the microbial community composition and structure of the rhizosphere soil, and microbial functions were also dramatically influenced by it. Four different microbes that had great potential in the biocontrol of clubroot disease were identified from the obtained results; they were the genera Pseudomonas, Gemmatimonas, Sphingomonas, and Nocardioides. Soil pH, organic matter contents, total nitrogen, and cation exchange capacity were the major environmental factors modulating plant microbiome assembly. In addition, microbial environmental information processing was extremely strengthened when the plant was subjected to pathogen invasion, but weakened when the disease became serious. In particular, oxidative phosphorylation and glycerol-1-phosphatase might have critical functions in enhancing Chinese cabbage's resistance to clubroot disease. This work revealed the interactions and potential mechanisms among Chinese cabbage, soil environmental factors, clubroot disease, and microbial community structure and functions, which may provide a novel foundation for further studies using microbiological or metabolic methods to develop disease-resistant cultivation technologies.

Deteksi Bakteri Pseudomonas cichorii Terbawa Benih Sawi Putih Impor Asal Korea Selatan dengan Metode PCR

Chinese cabbage (Brassica pekinensis L.) is one of the horticultural commodities that has a high production level in Indonesia. The increase in chinese cabbage production means that the need for chinese cabbage seeds in Indonesia is met through imported. The entry of seeds into a country through imported activities has the potential to as carriers of pathogens, especially bacteria that are OPTK A1 and A2, so it is important to carry out early detection of pathogens to prevent their spread in Indonesia. This research aims to detect bacteria carried by chinese cabbage seeds from South Korea using the PCR (Polymerase Chain Reaction) method. The results of the observations did not find the target bacteria Pseudomonas cichorii.

Greenhouse gas emissions and their driving factors among different flowering Chinese cabbage (Brassica campestris L.) varieties.

Crop cultivars have an influence on greenhouse gas (GHG) emissions, and there is variation between varieties. However, there are few reports available on the differences in GHG emissions and their driving factors among vegetable varieties. In this study, we conducted a field experiment to examine the variances in GHG emissions and their contributing factors among eight flowering Chinese cabbage varieties (considering growth period, leaf shape, and colour). The results showed significant differences in GHG emissions within varieties; early-maturing varieties exhibited GHG by 25.6% and 15.3%, respectively, when compared to mid- and late-maturing varieties. Among the different leaf types and color classifications, light-colored and sharp-leafed varieties had the lower global warming potential (GWP) overall. Cumulative CO2 emissions were influenced by leaf SPAD values and biomass, while cumulative N2O emissions were driven mainly by stem thickness, carbon accumulation, leaf SPAD values, and biomass. In summary, the selection of light-colored varieties with pointed leaves and shorter growth periods in actual production contributed positively to the reduction of carbon emissions from flowering Chinese cabbage production. Through efficient variety screening, this study provides a win-win strategy for achieving efficient vegetable production while also addressing the global climate challenge.

Enhancing Chinese Cabbage Production and Quality through IoT-Based Smart Farming in NFT-Hydroponics

The rising adoption of agricultural technologies such as the Internet of Things (IoT) or “smart farming” aims to boost crop production in terms of both quantity and quality. This study compares the benefits of a smart farm employing an IoT-based hydroponic system with those of a conventional hydroponic farm, using Chinese cabbage (Brassica pekinensis L.) as the experimental crop. Our primary objective was to automate environmental monitoring, achieving pH level and electrical conductivity (EC) maintenance through smartphone or computer interfaces for nutrient and acid–base solution adjustments. Additionally, we evaluated plant growth and crop quality, finding superior results with the smart hydroponic system. On average, there were substantial increases in various parameters, including total fresh weight (27.14%), total dry weight (48.90%), plant height (11.14%), stem diameter (32.89%), leaf area (94.30%), leaf width (32.36%), leaf length (38.12%), and chlorophyll content (22.73%). Nitrate accumulation in the edible parts of Chinese cabbage remained within safe limits for both systems, reflecting careful nutrient management. These findings highlight the potential of IoT-based technology in enhancing productivity and quality in hydroponic farming, marking a significant step towards revolutionizing traditional agricultural practices for more efficient crop production systems.

Drought Tolerance Evaluation and Growth Response of Chinese Cabbage Seedlings to Water Deficit Treatment

Drought is a significant climatic factor that significantly affects the production of Chinese cabbage, a crop that is highly susceptible to drought stress. The development and cultivation of drought-tolerant varieties could be a viable strategy to minimize the damage caused by climate change and ensure stable production of Chinese cabbage. This requires the implementation of technologies for early evaluation and selection of a plethora of resources. In this study, we screened 100 varieties and breeding resources for drought tolerance under a water deficit treatment at the seedling stage. We also evaluated the growth response of Chinese cabbage varieties and breeding resources under water deficit treatment and selected drought-tolerant Chinese cabbage genotypes. We confirmed that the visual score for wilting, which evaluates the wilting response during the recovery process of Chinese cabbage seedlings through water deficit treatment and re-watering, can be used as an indicator for evaluating tolerance to drought stress. The visual score for wilting showed a high correlation with major traits representing drought tolerance. Our findings highlight the need for an integrated approach that considers various environmental conditions, varieties, and lines to select and develop drought-tolerant varieties. We selected ‘18-FH112-1’ and ‘18-FH112-1-2’ among others, and these germplasms will be useful resources for drought tolerance breeding. This study provides a foundation for future efforts to develop drought-tolerant Chinese cabbage varieties, thereby contributing to the stable production of this crucial crop.

A hybrid simulation framework for predicting virus impacts on Chinese cabbage yields

AbstractSustainable production of Chinese cabbage (Brassica rapa L.) is essential for the economy and food security in South Korea. However, climate change poses significant threats to its growth and quality. Changes in precipitation patterns, such as drought and heavy rain, can affect the development of crop, leading to stunted growth or disease. This can lead to significant losses in crop yield. In this study, a hybrid modeling system was developed to predict the incidence of viral disease and evaluate impacts of combination of virus infection and environmental variabilities (including climate and location) on marketable cabbage yields. The crop growth model was successfully developed using a limited number (n = 7) of previous studies (root mean square error 0.25–0.33 Mg ha−1, R2 = 0.87–0.99). The developed hybrid modeling system was composed of a virus incident model and a crop growth model. According to simulated results, all study locations had around 20% incidence rates. However, based on the simulation results, the rates of viral disease incidence varied depending on the climate of each year. Among several climatic factors, precipitation had the greatest effect on virus outbreaks. Jeju Island, which had relatively high rainfall, had a higher disease incidence rate than other provinces. According to shared socioeconomic pathways (SSPs), in SSP245 (an intermediate development pathway), the yield of 1.58 Mg ha−1 was reduced to 1.26 Mg ha−1 due to a 25% viral disease outbreak. In SSP585 (a high development pathway), with an incidence of 23%, the yield was reduced by 0.2 Mg ha−1. These results will be useful for efficiently cultivating crops under various climatic conditions and seeking management methods to minimize damage from viral disease.

Cleaner production of Chinese cabbage by intercropping from Cd contaminated soil: Effects of hyperaccumulator variety and planting strip width

The utilization of Cd-contaminated soil in vegetable crop production can lighten the food crisis and improve the soil environmental resilience. Intercropping is a reliable technology in safety production from contaminated soil. A field-scale experiment was carried out to unravel how plant species and pattern affect the growth and Cd uptake of Chinese cabbage from Cd contaminated land. Among all the intercropping systems designed in this study, one row of Chinese cabbage intercropping with one row of Solanum nigrum L. is the best planting mode (high yields (2.78 kg/m2) and low Cd accumulation (0.02 mg/kg) of Chinese cabbage). Combined with the in-depth joint analysis of diverse soil physicochemical features (soil nutrient characteristics and microbial community structure), biomass yield and quality, and soil microbiological properties, we elaborated that two measures (screening hyperaccumulation types and controlling planting strip width) were the major factors in determining the growth of the aboveground and underground parts of Chinese cabbage respectively, thus directly regulating the application effectiveness of intercropping technology. The intertwined mechanisms (interspecific and intraspecific relationship) of different intercropping systems are summarized, which include better utilization of space, light and other resources in the aboveground part, bioavailability of nutrient, drive of soil bacteria and alleviated soil Cd stress in the underground part, etc. Our research outputs indicate the effectiveness and feasibility of intercropping can be improved by optimizing the streamline configuration and plant mode, which provide theory of reference and practical evidence for warranting the food safety and agricultural soil remediation simultaneously.

Bio-Geophysical Suitability Mapping for Chinese Cabbage of East Asia from 2001 to 2020

The cultivation of Chinese cabbage is a crucial source of daily vegetable supply for both human consumption and livestock feed, particularly in East Asian countries. However, changes in global climate and land usage have resulted in significant shifts in the ecological conditions suitable for Chinese cabbage production, thereby threatening its productivity. To address this issue, this study was conducted to map the bio-geophysical suitability of Chinese cabbage in East Asia (Japan, Northeast China, South Korea, and North Korea) from 2001 to 2020. This study integrated six key factors—temperature, rainfall, photosynthetically active radiation (PAR), soil nitrogen, soil pH, and soil texture—into a seasonal and monthly bio-geophysical suitability assessment using a GIS-based Analytic Hierarchy Process–Multiple-Criteria Decision-Making Analysis (AHP-MCDA). The levels of bio-geophysical suitability were categorized into four levels: optimal, suitable, marginal, and unsuitable. The findings of the study firstly indicate that summer is the optimal season for Chinese cabbage cultivation, as it was found to have the highest level of optimal suitability among the four seasons in East Asia. South Korea has the largest percentage of optimal and suitable areas compared to the other three countries. Secondly, this study also conducted a comparison analysis between bio-geophysical suitability and Normalized Difference Vegetation Index (NDVI) over 20 years, and the results show good consistency between the two indicators, with the highest R2 value being 0.61. Thirdly, the comparison between bio-geophysical suitability and production data in two villages in Japan demonstrates that an increase in suitability from 0.28 to 0.32 indicates a significant increase in production. Production would stay stable even with further increases in suitability. Finally, two case studies with monthly comparisons of bio-geophysical suitability across Japan and East Asia in 2020 provide an effective benchmark for determining optimal sowing and harvest times. This study’s results can provide important insights into the trade of Chinese cabbage and support the development of agricultural insurance programs both for farmers and insurance companies. Furthermore, this approach may also be applicable for the assessment of the suitability of other crops.

Oil palm leaf ash's effect on the growth and yield of Chinese cabbage (<i>Brassica rapa</i> L.)

<abstract> <p>The production of Chinese cabbage (<italic>Brassica rapa</italic> L.) has not been able to keep up with consumers' demand. Appropriate application of fertilizers is a key element in boosting plant productivity. One of the problems faced when fertilizing is that plant nutrient uptake has low efficiency. The application of basic nitrogen–phosphorus–potassium (NPK) fertilizers is typically the main emphasis of traditional agriculture, whereas the need for micronutrients, including Si, receives less consideration. Organic and inorganic materials are sources of Si nutrients. Currently, organic materials include straw or rice husks. The use of oil leaf palm waste as a source of nutrients is relatively still rare. The oil palm leaf ash in the production of Chinese cabbage is still not yet been researched. This analysis aims to know the optimal of oil palm leaf ash for the growth and yield of Chinese cabbage. The growth parameters measured 40 days after planting: leaf number, plant height, crown diameter, and fresh weight were impacted by the usage of oil palm leaf ash. A combination of oil palm ash at a concentration of 3.75 kg/m<sup>2</sup> and manure at a concentration of 1500 kg/m<sup>2</sup> produced the greatest results. In general, the usage of oil palm leaf ash affected the growth of Chinese cabbage, but the results could not be statistically separated from the role of manure as a source of NPK for plants. It was also demonstrated that the use of oil palm leaf ash increased the resistance of Chinese cabbage to armyworms. Therefore, Si for agriculture it can be utilized from oil palm leaf ash as a natural source.</p> </abstract>

The Effects of Climate Change on Heading Type Chinese Cabbage (Brassica rapa L. ssp. Pekinensis) Economic Production in South Korea

Since Chinese cabbage is consumed fresh, its wholesale price varies with the total amount supplied on the market. However, in these days, climate variability presents a large threat to sustainable Chinese cabbage production in South Korea. To manage Chinese cabbage production well under unexpected weather conditions, it is important to study the impacts of climate variability on Chinese cabbage economic yields in South Korea. In this study, 2-year field trials were conducted in multiple locations across seven provinces in South Korea. The collected morphological data from 24 different varieties were used to develop a yield prediction model using a machine learning technique. Three Chinese cabbage groups were carried out through the clustering analysis, and a yield model was developed for each cluster group. The developed model was used to predict the cabbage economic yields under different combinations of climate change and cropping management plans. According to simulation results, Group 1 had the shortest growing degree days and produced higher yields than the other two groups. However, the overproduction of Group 1 led to a price reduction in the market of (USD(0.04–0.08) per kg), which suggested that producing Group 2 of (USD(0.31–0.96) per kg) is more beneficial to farmers. Based on the production results of the groups, their revenue varied by location and cropping management. The results of this study provide farmers with a better understanding of the relationship between production and economic benefits in future climate change scenarios.

생육시기 기상을 활용한 배추 가격 예측

Domestic production of Chinese cabbage accounts for more than imports. As global warming intensifies, weather factors are expected to play an important role in the price fluctuations of Chinese cabbage due to the increase in the frequency and intensity of abnormal climates. Therefore, this study intends to predict the price of Chinese cabbage by using the weather factors for each growth stage considering the production of the main production area by cropping pattern. Based on the wholesale price of high-grade Chinese cabbage from May 20, 2015 to June 30, 2022, meteorological data for the same day and growth stage were also used in this study. The price of Chinese cabbage was predicted through Long Short-Term Memory(LSTM) and Gated Recurrent Unit(GRU), which are recurrent neural network models, and evaluated based on Root Mean Square Error(RMSE) and Mean Absolute Error(MAE). As a result of the analysis, the absolute difference in price was the smallest when forecasting reflecting the average of insolation during total growing, average of insolation during planting and sowing, and average of minimum grass temperature after planting and during harvest. When the price fluctuation trend was steep, more accurate prediction was possible when the weather of the day was also reflected. In this study, it is difficult to take into account the variation of individual growing seasons by day by applying the average data of a certain growth period to all cropping pattern in question. It is expected that a more accurate prediction can be obtained if the follow-up study is conducted by collecting the growth stage period by farmhouse. Through this study, it is expected that it will help farmers and consumers to sell and purchase based on the predicted price by properly applying weather variables after identifying the trend of the price of Chinese cabbage in the future.

Fine mapping and candidate gene analysis of CRA3.7 conferring clubroot resistance in Brassica rapa.

In this study, we fine-mapped a clubroot resistance gene CRA3.7 in Chinese cabbage and developed its closely linked marker syau-InDel3008 for marker-assisted selection in CR cultivars breeding. Chinese cabbage is an important leafy vegetable rich in many nutrients widely grown in China. Clubroot disease caused by an obligate biotrophic pathogen Plasmodiophora brassicae was rapidly spread and challenged to Chinese cabbage production. A clubroot resistance (CR) gene, CRA3.7, was mapped on chromosome A03 of Brassica rapa. A Chinese cabbage line 'CR510', which harbor homozygous resistance locus CRA3.7 was selected from a BC4F3 family. 'CR510' was crossed with a clubroot susceptible Chinese cabbage inbred line '59-1'. Total 51 recombinant plants were identified from an F2 population including 3000 individuals. These recombinants were selfed and the clubroot resistance of F2/3 families was evaluated. Finally, a clubroot resistance gene CRA3.7 was fine-mapped to an interval of approximately 386 kb between marker syau-InDel3024 and syau-InDel3008. According to the reference genome, total 54 genes including five encoding the TIR-NBS-LRR proteins was annotated in the fine-mapped region. Further, nine candidate's gene expression in parental lines at 7, 14 and 21 days after inoculation of P. brassicae were evaluated. Bra019376, Bra019401, Bra019403 and Bra019410 are highly expressed in 'CR510' than '59-1'. Gene sequence of Bra019410 from 'CR510' was cloned and identified different from CRa. Therefore, Bra019376, Bra019401, Bra019403 and Bra019410 are the most likely candidates for CRA3.7. Our research provides a valuable germplasm resource against P. brassicae Pb3 and CRA3.7 closely linked marker for marker-assisted selection in CR cultivars breeding.

First Report of Chinese Cabbage Wilt Caused by Plectosphaerella cucumerina in Inner Mongolia of China.

Chinese cabbage [Brassica rapa L. subsp. pekinensis (Lour.) Hanelt] has been grown commercially for many decades in Huade County, Inner Mongolia. In 2018 and 2019, an unusual stem and leaf wilt disease with an average disease incidence of approximately 3% was observed. Diseased plants with spindle-shaped stem lesions were collected and small pieces (0.3 × 0.3 cm) of the diseased tissues were cut from the margins of stem lesions, surface sterilized with 75% alcohol for 3 to 5 s, 0.1% NaClO for 2 to 3 min, and washed three times with sterilized water. The treated tissues were placed on 1.5% (w/v) water agar plates and incubated at 25°C for 3 days. The mycelia were cut and transferred onto potato dextrose agar (PDA) for culture purification. Three isolates with similar morphology were obtained and named as BC-2, BC3-2 and BG2. To confirm their pathogenicity, Chinese cabbage (cv. Chunqiuhuang) seed was planted into plugs. After 30 days, the fibrous roots were wounded with a fruit knife and root-dipped in the conidium suspension (1 × 106 conidia/ml) for 20 min. Inoculated seedlings were transplanted in pots (30 × 25 cm) with sterilized nursery soil, with one seeding per pot. The roots of control plants were also wounded and dipped in sterilized water. Five seedlings were inoculated with each isolate and the experiment was repeated three times. Treated seedlings were maintained in a greenhouse at 25 to 28°C under a 12-h photoperiod. Chlorosis and wilting were observed approximately 4 weeks after inoculation, and the outer layer of leaves of the inoculated seedlings developed discoloration and wilted symptoms after 50 days. The symptoms induced by all three isolates were the same as the symptoms observed in the field, whereas no symptoms developed on the control plants. To confirm the Koch's postulates, the fungus was successfully re-isolated from the infected leaves and had similar growth and morphology as the original isolates. The three isolates were cultured for both morphology and molecular identification. The 14-day-old colonies on PDA were buff or salmon pink with few aerial hyphae, and slimy surfaces. Aerial hyphae were sparse with simple or branched conidiophores. Conidia were ellipsoidal, hyaline, surface smooth, septate or aseptate, and (4.0 to 9.7 μm × 2.0 to 3.9 μm). Such characteristics are typical of Plectosphaerella spp. (Palm et al. 1995). For molecular identification, the internal transcribed spacer (ITS) region of rDNA was amplified using the primer pair ITS1/ITS4 (White et al. 1990), and the products were directly sequenced. BLAST analysis showed that the sequences of Isolates BC-2 (511 bp out of 515 bp), BC3-2 (512 bp out of 516 bp) and BG2 (503 bp out of 505 bp) showed 99% identity to an isolate of P. cucumerina (acc. no. KT826571.1) from Bottle gourd [Lagenaria siceraria (Molina) Standl.] (Yan et al. 2016). The sequences of Isolates BC-2, BC3-2 and BG2 were deposited in GenBank (acc. nos. MW320463, MW320462 and MW320464). Although P. cucumerina was reported causing root rot of cabbage (B. oleracea) in Gansu, China (Li et al. 2017), to our knowledge, this is the first report of P. cucumerina causing Chinese cabbage wilt in Inner Mongolia, China. The presence of the disease could cause significant economic losses in Chinese cabbage production. For this reason, strategies for the management and control of this disease should be implemented.

Identification of genes related to tipburn resistance in Chinese cabbage and preliminary exploration of its molecular mechanism

BackgroundTipburn, also known as leaf tip necrosis, is a severe issue in Chinese cabbage production. One known cause is that plants are unable to provide adequate Ca2+ to rapidly expanding leaves. Bacterial infection is also a contributing factor. Different cultivars have varying degrees of tolerance to tipburn. Two inbred lines of Chinese cabbage were employed as resources in this research.ResultsWe determined that the inbred line ‘J39290’ was the tipburn resistant material and the inbred line ‘J95822’ was the tipburn sensitive material based on the severity of tipburn, and the integrity of cell membrane structure. Ca2+ concentration measurements revealed no significant difference in Ca2+ concentration between the two materials inner leaves. Transcriptome sequencing technology was also used to find the differentially expressed genes (DEGs) of ‘J95822’ and ‘J39290’, and there was no significant difference in the previously reported Ca2+ uptake and transport related genes in the two materials. However, it is evident through DEG screening and classification that 23 genes are highly linked to plant-pathogen interactions, and they encode three different types of proteins: CaM/CML, Rboh, and CDPK. These 23 genes mainly function through Ca2+-CaM/CML-CDPK signal pathway based on KEGG pathway analysis, protein interaction prediction, and quantitative real-time PCR (qRT-PCR) of key genes.ConclusionsBy analyzing the Ca2+ concentration in the above two materials, the transcription of previously reported genes related to Ca2+ uptake and transport, the functional annotation and KEGG pathway of DEGs, it was found that Ca2+ deficiency was not the main cause of tipburn in ‘J95822’, but was probably caused by bacterial infection. This study lays a theoretical foundation for exploring the molecular mechanism of resistance to tipburn in Chinese cabbage, and has important guiding significance for genetics and breeding.

First report of Leptosphaeria biglobosa 'brassicae' causing Black Leg on Brassica rapa subsp. pekinensis in China.

Chinese cabbage [Brassica rapa L. subsp. pekinensis (Lour.) Hanelt] is a major leafy vegetable crop grown in China and eastern Asia (Fordham and Hadley 2003). In December 2018, black leg symptoms were observed on of "Qingza No.3" of Chinese cabbage during harvest, Chibi (29°46'37.38''N, 114°05'6.88''E), Hubei, China. Symptoms were first noted in late Nov. as black spots on leaf petioles and basal stems. Then, black spots enlarged as oval or irregular-shaped grayish lesions. Finally, lesions enlarged and coalesced with black pycnidia were observed, and some diseased leaves became blighted. The disease incidence was about 80% in three fields surveyed (~2 ha in total). Diseased plant tissues were surface-sterilized, and incubated on potato dextrose agar (PDA) plates at 20°C for 4 days. Three fungal isolates, namely EP9-19, EP9-22 and EP9-26, were obtained from five of the diseased samples; all produced fluffy, white aerial mycelia and a yellow pigment on PDA. After 14 days, black-brown and globose pycnidia were produced, approximately 150 μm in diameter (n = 50). In addition, pink pycnidiospore ooze was observed on the top of pycnidium after 20-day culturing on a V8-juice (20%) agar. Conidia were cylindrical and hyaline, with the mean size of 4.6 × 2.7 μm (n = 50). Two fungal species have been reported to cause blackleg on Brassica crops (Williams and Fitt 1999), i.e. Leptosphaeria maculans and L. biglobosa. The former is much more destructive, but is not present in China. These isolates had morphological characteristics matching those of L. biglobosa (Williams and Fitt 1999). The genomic DNA of isolate EP9-22 was extracted and sequenced for its actin, β-tubulin and the internal transcribed spacer (ITS) region of ribosomal DNA as described by Vincenot et al. (2008). Sequences of ITS (GenBank accession no. MN238766), actin (MN242213) and β-tubulin (MN242214) for isolate EP9-22 showed 100%, 99.67%, and 97.93% identity to the corresponding regions of L. biglobosa 'brassicae' strain IBCN89 (Vincenot et al. 2008). In addition, the phylogenetic analysis also indicated that isolate EP9-22 belonged to L. biglobosa 'brassicae'. The pathogenicity test was performed according to established protocols (Balesdent et al., 2005). Cotyledons of the 15-day-old Chinese cabbage seedlings (cultivars Xiaoza No.55 and Hualiangzao No.5) were wound inoculated with 10 μl pycnidiospore suspension (1 × 107 conidia/ml) of the three isolates, with 20 cotyledons per isolate, respectively, and 20 cotyledons wound inoculated with sterile water served as a control group. The treated seedlings were maintained at 20°C and 100% relative humidity with a 12-h photoperiod. The experiment was repeated twice. At 7 days after inoculation, necrotic lesions became visible surrounding inoculation sites for the three isolates, while the control group remained healthy. Fungal isolates showing a similar colony morphology to the originals were re-isolated from ten diseased cotyledons but not from the control cotyledons. Based on these results, L. biglobosa 'brassicae' was shown to be the causal agent of blackleg on Chinese cabbage in China. We believe that this disease has historically often been misidentified as 'anthracnose' by local famers. The threat from L. biglobosa to the production of Chinese cabbage has been assessed. This accurate identification of the causal pathogen is a critical first step towards the development of disease management strategies.

Root morphology ion absorption and antioxidative defense system of two Chinese cabbage cultivars (Brassica rapa L.) reveal the different adaptation mechanisms to salt and alkali stress.

Salt stress and alkali stress are major factors that affect the growth and production of Chinese cabbage. To explore their tolerant mechanism to salt and alkali stress, three salinity levels (0, 50, 100mmol/L NaCl) and three different pH levels (pH6.5, pH7.5, pH8.5) were interactively applied on Qinghua (salt-tolerant-alkali-sensitive) and Biyu (salt-sensitive-alkali-tolerant) cultivars; the root morphology, ion content and antioxidant enzymes were determined. The results showed that the root morphology and root water content of Qinghua under S0pH7.5 and S0pH8.5 were seriously affected, and the content of H2O2 and MDA increased by 143%, 190% and 234%, 294%, respectively, compared with S0pH6.5; when Biyu was under S50pH6.5 and S100pH6.5 stress, the content of H2O2 and MDA increase to 152%, 208% and to 240%, 263%, respectively, but the activities and genes expression of SOD, POD, CAT, AAO, APX, DHAR and MDHAR did not change. The root and the contents of H2O2 and MDA were not affected when Qinghua was treated with salt and Biyu was treated with alkali, but the activities of the antioxidant enzymes increased to 150-200%, and their relative expression was overexpressed and 2.5-3.5-fold of the S0pH6.5. The increase of Na+ in Qinghua was limited under salt stress, Mg2+ in Biyu increased significantly under alkali stress. These all indicated that the adaptability of roots could reflect the degree of tolerance; Chinese cabbage with high salt and alkali tolerance enhanced the regulation of their absorption of ions and increased the relative expression and activities of related antioxidant enzymes.

Gene co-expression network analysis reveals key pathways and hub genes in Chinese cabbage (Brassica rapa L.) during vernalization

BackgroundVernalization is a type of low temperature stress used to promote rapid bolting and flowering in plants. Although rapid bolting and flowering promote the reproduction of Chinese cabbages (Brassica rapa L. ssp. pekinensis), this process causes their commercial value to decline. Clarifying the mechanisms of vernalization is essential for its further application. We performed RNA sequencing of gradient-vernalization in order to explore the reasons for the different bolting process of two Chinese cabbage accessions during vernalization.ResultsThere was considerable variation in gene expression between different-bolting Chinese cabbage accessions during vernalization. Comparative transcriptome analysis and weighted gene co-expression network analysis (WGCNA) were performed for different-bolting Chinese cabbage during different vernalization periods. The biological function analysis and hub gene annotation of highly relevant modules revealed that shoot system morphogenesis and polysaccharide and sugar metabolism caused early-bolting ‘XBJ’ to bolt and flower faster; chitin, ABA and ethylene-activated signaling pathways were enriched in late-bolting ‘JWW’; and leaf senescence and carbohydrate metabolism enrichment were found in the two Chinese cabbage-related modules, indicating that these pathways may be related to bolting and flowering. The high connectivity of hub genes regulated vernalization, including MTHFR2, CPRD49, AAP8, endoglucanase 10, BXLs, GATLs, and WRKYs. Additionally, five genes related to flower development, BBX32 (binds to the FT promoter), SUS1 (increases FT expression), TSF (the closest homologue of FT), PAO and NAC029 (plays a role in leaf senescence), were expressed in the two Chinese cabbage accessions.ConclusionThe present work provides a comprehensive overview of vernalization-related gene networks in two different-bolting Chinese cabbages during vernalization. In addition, the candidate pathways and hub genes related to vernalization identified here will serve as a reference for breeders in the regulation of Chinese cabbage production.