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    Effects of potassium application rate on lipid synthesis and eating quality of two rice cultivars
    CHEN Guang-yi, PENG Li-gong, LI Cong-mei, TU Yun-biao, LAN Yan, WU Chao-yue, DUAN Qiang, ZHANG Qiu-qiu, YANG Hong, LI Tian
    DOI: 10.1016/j.jia.2022.09.020 Online: 23 September 2022

    Lipid content has an important effect on rice eating quality, but the effects of fertilizer application rate on lipid synthesis and eating quality of rice are not well understood.  Potassium (K) has a great influence on rice quality and the requirements for K fertilizer is greater than that of nitrogen (N) and phosphate (P) fertilizer in rice.  To investigate the effects of K fertilizer on lipid synthesis and eating quality of rice, we used Nanjing (NJ) 9108 (japonica) and IR72 (indica) rice as experimental materials and four K levels, K0 (0 kg ha-1), K1 (90 kg ha-1), K2 (135 kg ha-1) and K3 (180 kg ha-1).  The results showed that the lipid, free fatty acid (FFA) content, unsaturated fatty acid (UFA) content, malonyl-CoA (MCA) content, phosphatidic acid (PA) content, lipid synthesis-related enzyme activities and eating quality of both cultivars first increased and then decreased with increasing K.  The maximum values were obtained under K2.  However, the saturated fatty acid (SFA) content showed the opposite trend.  No significant differences were found in pyruvate (PYR) content between K treatments.  Protein and oxaloacetic acid (OAA) contents and phosphoenolpyruvate carboxylase (PEPCase) activity of NJ 9108 first increased and then decreased with increasing K and the minimum values were obtained under K2 while IR72 showed the opposite trend and the maximum values were obtained under K1.  Overall, increasing K optimized fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis.  The optimal K application rate for lipid synthesis, eating quality and grain yield of both cultivars was 135 kg ha-1.

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    Visual learning graph convolution for multi-grained orange quality grading
    GUAN Zhi-bin, ZHANG Yan-qi, CHAI Xiu-juan, CHAI Xin, ZHANG Ning, ZHANG Jian-hua, SUN Tan
    DOI: 10.1016/j.jia.2022.09.019 Online: 22 September 2022

    The quality of oranges is grounded on their appearance and diameter. Appearance refers to the skin's smoothness and surface cleanliness; diameter refers to the oranges' transverse diameter size. They are visual attribute features that visual perception technologies can automatically identify. Nonetheless, two issues need to be addressed in the current orange quality grading task: 1) There are no image datasets that can be employed for orange quality grading; 2) It is challenging to effectively learn the fine-grained and distinct visual semantics of oranges from diverse angles. For multi-grained grading tasks, 12,522 images obtained from 2,087 oranges are collected. In addition, we present a visual learning graph convolution approach for multi-grained orange quality grading, including a backbone network and a graph convolutional network (GCN). The backbone network's object detection, data augmentation, and feature extraction can remove extraneous visual information. GCN is utilized to learn the topological semantics of orange feature maps. Finally, evaluation results prove that the recognition accuracy of diameter size, appearance, and fine-grained orange quality is 99.5%, 97.27%, and 97.99%, respectively, indicating that the proposed approach is superior to others.

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    IPM-Biological and integrated management of the desert locust
    LI Shuang, FENG Shi-qian, Hidayat ULLAH, TU Xiong-bing, ZHANG Ze-hua
    DOI: 10.1016/j.jia.2022.09.017 Online: 20 September 2022

    Locusts have caused periodic disasters in the recorded history of mankind. Up to now, locust disaster is still the biggest threat to the world’s agricultural production. The desert locust Schistocerca gregaria is one of the most serious locusts, which not only caused a massive food crisis and economic losses but also caused ecological disasters. The desert locust is a migratory insect pest that occurs year-round in the tropic and subtropical regions, and under the influence of wind and seasonal alternation, it moves and flies in the African continent and West Asia. Desert locust damages the stems and leaves of more than 300 plants including Gramineae, Tribulus terrestris, and Euphorbiaceae. Upon migration, locusts’ cause devastating disasters to local plants, especially crops, and seriously threaten food security. To date, much research has been conducted regarding the ecology and management of desert locusts. This review represents an effort to summarize the basic information on the biology and ecology, distribution, damage and economic impact of desert locusts, and the more or less recent developments in integrated locust management and making recommendations for future research. 

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    Molecular diagnosis and direct quantification of cereal cyst nematode (Heterodera filipjevi) from field soil using TaqMan real-time PCR
    JIAN Jin-zhuo, HUANG Wen-kun, KONG Ling-an, JIAN Heng, Sulaiman ABDULSALAM, PENG De-liang, PENG Huan
    DOI: 10.1016/j.jia.2022.09.016 Online: 20 September 2022

    Heterodera filipjevi continues to be a major threat to wheat production worldwide. Rapid detection and quantification of cyst nematodes are essential for more effective control against this nematode disease. In the present study, a TaqMan-minor groove binder (TaqMan-MGB) probe-based fluorescence quantitative real-time polymerase chain reaction (qPCR) was successfully developed and used for quantifying H. filipjevi from DNA extracts of soil. The primers and probe designed from the obtained RAPD-SCAR marker fragments of H. filipjevi showed high specificity to H. filipjevi using DNA from isolates confirmed species of 23 Heterodera spp., 1 Globodera spp. and 3 Pratylenchus spp. The qPCR assay is highly sensitive and provides improved H. filipjevi detection sensitivity of as low as 4-3 single J2 DNAs, 10-3 female DNAs, and 0.01 μg μL-1 genomic DNAs. A standard curve relating the threshold cycle and log values of nematode numbers was generated and validated from artificially infested soils and was used to quantify H. filipjevi in naturally infested field soils. There was a high correlation between the H. filipjevi numbers estimated from 32 naturally infested field soils by both conventional methods and the numbers quantified using the qPCR assay. qPCR potentially provides a useful platform for the efficient detection and quantification of H. filipjevi directly from field soils and to quantify this species directly from DNA extracts of field soils.

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    Hole fertilization in the root zone facilitates maize yield and nitrogen utilization by mitigating potential N loss and improving mineral N accumulation
    SHI Wen-xuan, ZHANG Qian, LI Lan-tao, TAN Jin-fang, XIE Ruo-han, WANG Yi-lun
    DOI: 10.1016/j.jia.2022.09.018 Online: 20 September 2022

    Reducing environmental impacts and improving N utilization are critical to ensuring food security in China. Although root-zone fertilization has been considered an effective strategy to improve nitrogen use efficiency (NUE), the effect of controlled-release urea (CRU) applied in conjunction with normal urea in this mode is unclear. Therefore, a 3-yr field experiment was conducted using a no-N-added as a control and two fertilization modes (FF, furrow fertilization by manual trenching, i.e., farmer fertilizer practice; HF: root-zone hole fertilization by point broadcast manually) at 210 kg N ha-1 (controlled-release:normal=5:5), along with a one-year in-situ microplot experiment. Maize yield, NUE and N loss were investigated under different fertilization modes. The results showed that compared with FF, HF improved the average yield and N recovery efficiency by 8.5 and 22.3% over three years, respectively. HF had a greater potential for application than FF treatment, which led to increases in dry matter accumulation, total N uptake, SPAD value and LAI. In addition, HF remarkably enhanced the accumulation of 15N derived from fertilizer by 17.2% compared with FF, which in turn reduced the potential loss of 15N by 43.8%. HF increased the accumulation of N in the tillage layer of soils at harvest for potential use in the subsequent season relative to FF. Hence, HF could match the N requirement of summer maize, sustain yield, improve NUE and reduce environmental N loss simultaneously. Overall, root-zone hole fertilization with blended CRU and normal urea can represent an effective and promising practice to achieve environmental integrity and food security on the North China Plain, which deserves further application and investigation.

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    Influence of two-stage harvesting on the properties of cold-pressed rapeseed (Brassica napus L.) oils
    NING Ning, HU Bing, BAI Chen-yang, LI Xiao-hua, KUAI Jie, HE Han-zi, REN Yi-lin, WANG Bo, JIA Cai-hua, ZHOU Guang-sheng, ZHAO Si-ming
    DOI: 10.1016/j.jia.2022.09.015 Online: 16 September 2022
    The harvesting process is important in rapeseed (Brassica napus L.) production. The seed yield, oil quality, and industrial efficiency varied depending on the harvesting methods. This investigation studied, the influences of harvesting methods on the quality of cold-pressed rapeseed oil using two varieties. The oil color, peroxide value (POV), tocopherol content, fatty acid composition, and polarity of total polyphenols (PTP) contents of two rapeseed varieties in Huanggang and Xiangyang were compared through artificially simulated combined harvesting and two-stage harvesting. Results showed significant differences in these quality indicators between the two harvesting methods. The red value (R-value), POV, total tocopherol contents, linoleic and linolenic acid content, and PTP content of the pressed rapeseed oil prepared by the combined harvesting method were about 27.6%, 5.7%, 15.8%, 2.0%, 0.5%, and 28.6% lower, respectively, than those of the two-stage harvesting method, and Xiangyang and Huayouza62 performed better in the two regions and varieties. To sum up, the rapeseed oil obtained at 38-41 days after final flowering of combined harvesting, 35 days after final flowering, and 6 days of post-ripening of the two-stage harvesting could elevate the quality of rapeseed oil.
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    SlGH9-15 regulates tomato fruit cracking with hormonal and abiotic stress responsiveness cis-elements

    LIN Hao-wei, WU Zhen, ZHOU Rong, CHEN Bin, ZHONG Zhao-jian, JIANG Fang-ling
    DOI: 10.1016/j.jia.2022.09.013 Online: 16 September 2022

    Fruit cracking occurs easily during late period of fruit development when encountering unsuitable environment, which dramatically affects fruit production and marketing. In our study, the bulked segregant RNA-Seq (BSR) was conducted to identify the key regulatory gene of fruit cracking in tomato. BSR-Seq analysis illustrated that two regions associated with irregularly cracking were located on chromosome 9 and 11 containing 127 candidate genes. Further, through differentially expression analysis and qRT-PCR in cracking-susceptible and cracking-resistant genotypes, the candidate gene SlGH9-15 (Solyc09g010210) with significantly differential expression level was screened. Bioinformatics analysis of the GH9 gene family revealed that 20 SlGH9 genes were divided into three groups. The phylogenetic analysis showed that SlGH9-15 was closely related to cell wall construction associated genes AtGH9B1, AtGH9B6, OsGH9B1 and OsGH9B3. The cis-acting elements analysis revealed that SlGH9-15 was activated by various hormones (ethylene and ABA) and abiotic stresses. The expression pattern indicated that 13 SlGH9 genes, especially SlGH9-15, were highly expressed in cracking-susceptible genotype and its expression level gradually increased during fruit development, and achieved maximum value at red ripe stage. Additionally, the cracking-susceptible tomato showed higher cellulase activity and lower cellulose content than that of cracking-resistant tomato, particularly at red ripe stage. This study identifies SlGH9-15 as key gene associated with fruit cracking in tomato for the first time, and gives new insights for understanding the molecular mechanism and complex regulatory network of fruit cracking.

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    Comprehensive analysis of the full-length transcripts and alternative splicing involved in clubroot resistance in Chinese cabbage
    SU He-nan, YUAN Yu-xiang, YANG Shuang-juan, WEI Xiao-chun, ZHAO Yan-yan, WANG Zhi-yong, QIN Liu-yue, YANG Zhi-yuan, NIU Liu-jing, LI Lin, ZHANG Xiao-wei
    DOI: 10.1016/j.jia.2022.09.014 Online: 16 September 2022

    Chinese cabbage is an economically important Brassica vegetable worldwide, while clubroot caused by the soil-borne protist plant pathogen Plasmodiophora brassicae is regarded as a destructive disease to Brassica crops. Previous studies on the gene transcripts of Chinese cabbage resistance to clubroot mainly employed RNA-seq technology, which cannot provide accurate transcript assembly and structural information. In the present study, PacBio RS II SMRT sequencing was applied to generate full-length transcriptomes of mixed roots 0, 2, 5, 8, 13, and 22 days after P. brassicae infection in the clubroot-resistant line DH40R. Overall, 39,376 high-quality isoforms and 26,270 open reading frames (ORFs) were discovered from SMRT sequencing data. Additionally, 426 annotated long noncoding RNAs (lncRNAs), 56 transcription factor (TF) families, 1,883 genes with poly(A) sites and 1,691 alternative splicing (AS) events were identified. Furthermore, 1,202 of the genes had at least one AS event in DH40R. A comparison with RNA-seq data revealed six differentially expressed AS genes (one for disease resistance and five for defense response) potentially involved in P. brassicae resistance. This study provides valuable resources for basic research on clubroot resistance in Chinese cabbage.

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    PpMAPK6 regulates peach bud endodormancy release through interactions with PpDAM6

    ZHANG Yu-zheng, XU Chen, LU Wen-li, WANG Xiao-zhe, WANG Ning, MENG Xiang-guang, FANG Yu-hui, TAN Qiu-ping, CHEN Xiu-de, FU Xi-ling, LI Ling
    DOI: 10.1016/j.jia.2022.09.010 Online: 10 September 2022

    The MADS-box (DAM) gene PpDAM6, which is related to dormancy, plays a key role in bud endodormancy release, and the expression of PpDAM6 decreases during endodormancy release. However, its interaction network that governs the regulation of the endodormancy release of flower buds in peach is still not very clear. In this study, we used yeast two-hybrid (Y2H) assays and identified a mitogen-activated protein kinase, PpMAPK6, that interacts with PpDAM6 in a peach dormancy-associated SSHcDNA library. PpMAPK6 is primarily located in the nucleus. Further Y2H and bimolecular fluorescence complementation (BiFC) assays verified that PpMAPK6 interacts with PpDAM6 by binding to the MADS-box domain of PpDAM6. Quantitative real-time PCR (qRT-PCR) analysis showed that the expression of PpMAPK6 was opposite that of PpDAM6 in the endodormancy release of three cultivars with different chilling requirements (Prunus persica cv. Chunjie, Prunus persica var. nectarina cv. Zhongyou 5, Prunus persica cv. Qingzhou peach). In addition, abscisic acid (ABA) inhibited the expression of PpMAPK6 and promoted the expression of PpDAM6 in flower buds. The results showed that PpMAPK6 might phosphorylate PpDAM6 to accelerate its degradation by interacting with PpDAM6. The expression of PpMAPK6 increased with decreasing ABA content during endodormancy release in peach flower buds, which in turn decreased the expression of PpDAM6 and promoted endodormancy rel

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    Changes in phenolic content, composition and antioxidant activity of blood oranges during cold and on-tree storage
    ZHAO Ji-chun, AO Miao, HE Xiao-qin, LI Wei-zhou, DENG Li-li, ZENG Kai-fang, MING Jian
    DOI: 10.1016/j.jia.2022.09.011 Online: 10 September 2022

    Citrus fruit is rich in phenolic compounds, which possess several health benefits. However, few studies have focused on the changes of phenolic compounds in these fruit during postharvest storage. In this study, the phenolic content, components and antioxidant activity of Tarocco blood oranges have been dynamically monitored during 12-week cold storage and on-tree storage. The alteration mechanism of phenolic compounds in blood oranges was investigated by evaluating phenylpropanoid pathway-related enzymes activities and genes expression. Results showed that flavanones were the main phenolic compound in the blood oranges, and both storage methods mainly stimulated the accumulation of phenolic acids to improve total phenolic content and reach the maximum content at week 12. Nonetheless, blood oranges had a higher phenolic content and antioxidant activity under on-tree storage than cold storage. Furthermore, the enzyme activities and gene expression to phenylpropanoid pathway demonstrated that the accumulation of phenolics in blood oranges during storage was highly related to the activation of the phenylpropanoid pathway. These results demonstrate that on-tree storage is a potential approach for extending the supply period of blood orange from the perspective of phenolic compounds.

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    QTL analysis of early flowering of female flowers in zucchini (Cucurbita pepo L.)
    QU Shu-ping, YANG Dan, YU Hai-yang, CHEN Fang-yuan, WANG Ke-xin, DING Wen-qi, XU Wen-long, WANG Yun-li
    DOI: 10.1016/j.jia.2022.09.009 Online: 10 September 2022

    Early flowering promotes early maturity and production, and the capacity to counteract biotic and abiotic stresses, making it an important agronomic trait in zucchini. In the present study, the zucchini inbred line ‘19’ showed significantly fewer days to blooming of the first female flower (DFF) than the inbred line ‘113’, which showed stable early flowering. Genetic analysis revealed that DFF is an inheritable quantitative trait and is controlled by multiple genes. Based on the strategy of quantitative trait locus (QTL) sequencing (QTL-seq) combined with linkage analysis, 3 QTLs for DFF were identified on chromosomes 4, 11 and 20. To validate these results, additional F2 populations grown under different environmental conditions were used for QTL mapping analysis of DFF with insertion/deletion (InDel) markers. Using the composite interval mapping (CIM) method of R/qtl software, only one major locus was identified under all environmental conditions and was located in a 117-kb candidate region on chromosome 20. Based on gene annotation, gene sequence alignment and qRT–PCR analysis, we found that the Cp4.1LG20g08050 gene encoding a RING finger protein may be a candidate gene for the opposite regulation of early flowering in zucchini. In summary, these results lay a foundation for better understanding early flowering, and improving early flowering-based breeding strategies in zucchini.

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    Functional analysis of MdSUT2.1, a plasma membrane sucrose transporter from apple
    ZHANG Bo, FAN Wen-min, ZHU Zhen-zhen, WANG Ying, ZHAO Zheng-yang
    DOI: 10.1016/j.jia.2022.09.012 Online: 10 September 2022

    Sugar content is a determinant of apple (Malus×domestica Borkh.) sweetness. However, the molecular mechanism underlying sucrose accumulation in apple fruit remains elusive. Herein, the role of the sucrose transporter MdSUT2.1 in the regulation of sucrose accumulation in apple was reported. The MdSUT2.1 gene encodes a protein with 612 amino acid residues that could be localized at the plasma membrane when expressed in tobacco leaf protoplasts. MdSUT2.1 was highly expressed in fruit and was positively correlated with sucrose accumulation during apple fruit development. Moreover, the sucrose transport activity of MdSUT2.1 was validated by complementary growth assays in a yeast mutant. MdSUT2.1 overexpression in apple and tomato resulted in significant increases in sucrose, fructose, and glucose contents compared to WT. Further analysis revealed that the expression levels of sugar metabolism- and transport-related genes SUSYs, NINVs, FRKs, HXKs, and TSTs increased in apple and tomato with MdSUT2.1 overexpression compared to WT. Finally, unlike the tonoplast sugar transporters MdTST1 and MdTST2, the promoter of MdSUT2.1 was not inducible by exogenous sugars. These findings provide valuable insights into the molecular mechanism underlying sugar accumulation in apple.

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    Commercial cash crop production and households’ economic welfare: Evidence from the pulse farmers in rural China
    MA Ji-liang, LI Fan, ZHANG Hui-jie, NAWAB Khan
    DOI: 10.1016/j.jia.2022.09.006 Online: 07 September 2022

    Whether promoting cash crop production can increase household welfare has long been the focus of the food policy debate. This study first investigated the determinants of household behavior in commercial pulse farming. It then examined how households' commercial pulse production improves their economic welfare. We used a dataset of 848 households collected from 2018 to 2019 to estimate the determinants of household behavior in commercial pulse farming by the Heckman two-step model. The endogenous treatment regression (ETR) method was employed to examine the impact of commercial pulse farming on household economic welfare. The results showed that factors such as market purchase prices, agricultural technology services, farmers' access to loans, and government subsidies promoted smallholders' commercial pulse farming; production costs and perceptions of climate change risks constrained smallholders' commercial pulse production. Overall, commercial pulse production has increased household farm income but there was a limited impact on household off-farm income. Our findings suggest that policies aiming to increase households' cash crop production and market access should significantly improve the economic welfare of pulse farmers.

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    Consumers' Experiences and Preferences for Plant-Based Meat Food: Evidence from a Choice Experiment in Four Cities of China
    WANG Ge, Madison T Plaster, Bai Yun-li, LIU Cheng-fang
    DOI: 10.1016/j.jia.2022.09.008 Online: 07 September 2022

    Based on data from an online survey conducted among 579 consumers in four big cities in China in early 2021, this paper examines consumers’ experiences in and preferences for plant-based meat (PBM) food and its correlates. To do so, we first described consumers’ experiences in consuming and purchasing PBM food as well as their correlates. Then we analyzed the data from a hypothetical choice experiment where consumers were given options of purchasing burgers made from PBM or animal-based meat (ABM), combined with different country of origin (COO), taste labels, and prices. Our data show that overall respondents hold positive attitudes towards PBM food; 85 (82) percent of respondents reported that they had the experience in eating (purchasing) PBM food. More than half of them ate PBM food for the reasons of trying new food (58 percent) or being interested in healthy food (56 percent). Income, religion, and dietary restrictions are found to be significantly correlated with consumers’ experiences in PBM food consumption. Results from Random Parameter Logit Model based on data from the hypothetical choice experiment show that 79 percent of respondents chose PBM burgers, and they are willing to pay 88 CNY to buy PBM burgers on average. We also find that 99.8 percent (83 percent) respondents are willing to buy burgers made in China (with taste label), with an average willingness to pay (WTP) of 208 (120) CNY. Heterogeneity test revealed that females, respondents with at least bachelor degree, higher income, religious beliefs, and dietary restrictions are more likely to buy PBM burgers than their counterparts. 

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    Development of a Texture Evaluation System for Dongzao (Ziziphus jujuba cv. Dongzao) Fruit
    KONG Xia-bing, XU Min, WAN Hao-liang, HAN Ling-xi, LIU Xiao-li, LI Qing-jun, HAO Bian-qing, ZHANG Shao-jun, LI Xiao-ming, LIU Yi-hui, NIE Ji-yun
    DOI: 10.1016/j.jia.2022.09.007 Online: 07 September 2022

    Dongzao (Ziziphus jujuba cv. Dongzao) is an excellent late maturing variety of fresh-eating jujube in China. Fruit texture is an important indicator of its sensory quality. To investigate the relationship among texture indices and establish an evaluation system for Dongzao fruit texture, a texture profile analysis (TPA) was performed on 1150 Dongzao fruit from three main Dongzao producing areas in China with the TMS-Touch instrument. A total of eight indices and their best-fit distribution were obtained, including fracture (Pearson), hardness (Inv Gauss), adhesive force (Weibull), adhesiveness (Log Logistic), cohesiveness (Log Logistic), springiness (Beta General), gumminess (Inv Gauss) and chewiness (Inv Gauss). Based on the best-fit distribution curve, each index was divided into five grades (lower, low, medium, high and higher) by the 10th, 30th, 70th and 90th percentiles. Among the texture indices, 82% of the correlation coefficients were highly significant (p<0.01), meanwhile chewiness was significant (p<0.01) positively correlated with springiness and gumminess, of which the correlation coefficients were up to 0.8692 and 0.8096 respectively.  However, adhesiveness was significant (p<0.01) negatively related to adhesive force with a correlation coefficient of –0.7569. Among hardness, cohesiveness, springiness, gumminess and chewiness, each index could be well fitted by multiple linear regression with the remaining four indices, with the coefficients of above 0.94 and the mean fitting error and mean prediction error lower than 10%. Then, a comprehensive evaluation model was established based on the factor analysis to evaluate the texture quality of Dongzao. The results demonstrated that Dongzao fruit with higher comprehensive scores generally exhibited higher springiness and chewiness while lower adhesive force and adhesiveness. By factor analysis and clustering analysis, the eight studied texture indices could be divided into four groups (cohesive factor, adhesive-soft factor, tough-hard factor and crispness factor), whose representative indices were springiness, adhesiveness, hardness and fracture, respectively. Overall, this study investigated the variation in each index of Dongzao fruit texture, explored the association among these indices, screened the representative indices, and established a texture evaluation system for Dongzao fruit. The results may provide a methodological basis and technical support for the texture evaluation of Dongzao.

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    Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation
    FENG Xu-yu, PU Jing-xuan, LIU Hai-jun, WANG Dan, LIU Yu-hang, QIAO Shu-ting, LEI Tao, LIU Rong-hao
    DOI: 10.1016/j.jia.2022.09.002 Online: 03 September 2022

    Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation, with the potential to save water and increase nitrogen (N) fertilizer efficiency. A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF. The treatments included three ADF frequencies with intervals of 3 (F3), 6 (F6) and 12 days (F12), and conventional drip fertigation as a control (CK), which was fertilized once every 6 days. For the ADF treatments, two drip tapes were placed 10 cm away on each side of the tomato row, and alternate drip irrigation was realized using a manual valve on the distribution tapes. For the CK treatment a drip tape was located close to the roots of the tomato plants. The total N application rate of all treatments was 180 kg ha-1. The total irrigation amounts applied to the CK treatment were 450.6 and 446.1 mm in 2019 and 2020, respectively; and the irrigation amounts applied to the ADF treatments were 60% of those of the CK treatment.  The F3 treatment resulted in water and N being distributed mainly in the 0-40-cm soil layer with less water and N being distributed in the 40-60-cm soil layer. The F6 treatment led to 21.0 and 29.0% higher 2-year average mineral N concentration in the 0-20 and 20-40-cm soil layer, respectively and a 23.0% lower N concentration in the 40-60-cm soil layer than in the CK treatment. The 2-year average tomato yields of the F3, F6, F12, and CK treatments were 107.5, 102.6, 87.2, and 98.7 t ha-1, respectively. The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment, whereas there was no significant difference between the F3 and F6 treatment. The F6 treatment resulted in yield similar to the CK treatment, indicating that ADF could maintain tomato yield with a 40% saving in water use. Based on the distribution of water and N, and tomato yield, a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.

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    Combining rhizosphere and soil-based P management decreased the P fertilizer demand of China by more than half based on LePA model simulations
    YU Wen-jia, LI Hai-gang, Peteh M Nkebiwe, YANG Xue-yun, GUO Da-yong, LI Cui-lan, ZHU Yi-yong, XIAO Jing-xiu, LI Guo-hua, SUN Zhi, Torsten MÜLLER, SHEN Jian-bo
    DOI: 10.1016/j.jia.2022.09.003 Online: 03 September 2022

    Phosphorus (P) is a finite natural resource and is increasingly considered to be a challenge for global sustainability. Agriculture in China plays a key role in global sustainable P management. Rhizosphere and soil-based P management are necessary for improving P–use efficiency and crop productivity in intensive agriculture in China. A previous study has shown that the future demand for phosphate fertilizer by China estimated by the LePA model (legacy phosphorus assessment model) can be greatly reduced by soil-based P management (the building-up and maintenance approach). The present study used the LePA model to predict the phosphate demand by  China through combined rhizosphere and soil-based P management at county scale under four P fertilizer scenarios: (1) Same P application rate as in 2012; (2) rate maintained same as 2012 in low-P counties or no P fertilizer applied in high-P counties until targeted soil Olsen-P (TPOlsen) level is reached, and then rate was the same as P-removed at harvest;  (3) rate in each county decreased to 1-7 kg ha-1 yr-1 after TPOlsen is reached in low-P counties, then increased by 0.1-9 kg ha-1 yr-1 until equal to P-removal; (4) rate maintained same as 2012 in low-P counties until TPOlsen is reached and then equaled to P-removal, while the rate in high-P counties is decreased to 1-7 kg ha-1 yr-1 until TPOlsen is reached and then increased by 0.1-9 kg ha-1 yr-1 until equal to P-removal. Our predictions showed that the total demand for P fertilizer by all China was 693 Mt P2O5 and according to scenario 4, P fertilizer could be reduced by 57.5% compared with farmer current practice, during the period 2013-2080. The model showed that rhizosphere P management led to a further 8.0% decrease in  P fertilizer use compared with soil-based P management. The average soil Olsen-P level in China only needs to be maintained at 17 mg kg-1 to achieve high crop yields. Our results provide a firm basis for government to issue relevant policies for sustainable P management in China.

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    Azole selenourea disrupted the midgut and caused malformed development of Plutella xylostella
    GUO Xue-ying, HUANG Zi-hao, XIONG Lan-tu, DONG Li, HUANG Yue-kun, WEI Lin-hao, TANG Ri-yuan, WANG Zhi-lin, XU Han-hong
    DOI: 10.1016/j.jia.2022.09.001 Online: 03 September 2022

    Chemical insecticides targeting the digestive system of diamondback moth (DBM), Plutella xylostella, have not been developed. The discovery of an insecticide with novel mode of action is a challenge for the control of DBM. In this study, a class of selenium- and difluoromethyl-modified azoles (fluoroazole selenoureas, FASU) were designed and synthesized for the control of DBM. Of these azoles, compound B4 showed the highest insecticidal activity against DBM. The LC50 of third- and second-instar larvae reached 32.3 and 4.6 μg mL-1, respectively. The midgut tissue of larvae was severely disrupted, and the larval intestinal tissue was dotted with unique red spots after treatment with compound B4. Compound B4 led to disintegration of the peritrophic matrix, swelling of the midgut epithelium, fracture of the microvilli, and extensive leakage of cellular debris in the midgut lumen. Surviving larvae grew very slowly, and the larval duration was significantly prolonged after exposure to compound B4 at sublethal doses (LC10, LC25 and LC50). Furthermore, the pupation rate, emergence rate and pupae weight were significantly decreased. Compound B4 also induced abnormal pupae, causing adults to be trapped in the cocoon or failure to fly due to twisted wings. These results demonstrated that FASU could reduce the population of DBM in sublethal doses. FASU is the first synthetic insecticidal lead compound that has been shown to disrupt the midgut tissue of the larvae of DBM, and its mode of action totally differs from that of commercial chemical insecticides.

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    MRUNet: A two-stage segmentation model for small insect targets in complex environments
    WANG Fu-kuan, HUANG Yi-qi, HUANG Zhao-cheng, SHEN Hao, HUANG Cong, QIAO Xi, QIAN Wan-qiang
    DOI: 10.1016/j.jia.2022.09.004 Online: 03 September 2022

    Online automated identification of farmland pests is an important auxiliary means of pest control. In practical applications, the online insect identification system is often unable to locate and identify the target pest accurately due to factors such as small target size, high similarity between species and complex backgrounds. To facilitate the identification of insect larvae, a two-stage segmentation method, MRUNet, was proposed in this study. Structurally, MRUNet borrows from Mask R-CNN's practice of object detection before semantic segmentation and then uses an improved lightweight UNet to perform the semantic segmentation. To reliably evaluate the segmentation results of the models, statistical methods were introduced to measure the stability of the performance of the models among samples in addition to the evaluation indicators commonly used for semantic segmentation. The experimental results showed that this two-stage image segmentation strategy is effective in dealing with small targets in complex backgrounds. Compared with existing state-of-the-art semantic segmentation methods, MRUNet shows better stability and detail processing ability under the same conditions. This study provides a reliable reference for the automated identification of insect larvae.

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