Acta Agriculturae Zhejiangensis

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2023, 35(4): 0-0.

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Effects of shading on agronomic characters, yield and nitrogen metabolism of 10 vegetable soybean varieties

TAN Shuxia, ZHAO Taodi, YANG Hao, NING Kejun, LIU Li, HE Qingyuan, HUANG Shoucheng, SHU Yingjie

2023, 35(4): 729-735. DOI: 10.3969/j.issn.1004-1524.2023.04.01

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In order to screen out suitable vegetable soybean varieties for intercropping with high stem crops, 10 vegetable soybean varieties were selected as test materials. The effects of 50% shading at either four leaf stage or early flowering stage on agronomic characters, yield and root nitrate nitrogen ( $NO 3 -$ -N) content and nitrate reductase (NR) activity were explored. Besides, the shade tolerance of 10 vegetable soybean varieties were determined via comprehensive membership function method. The results showed that, the plant height, pod setting height, branch height and root $NO 3 -$ -N content of some vegetable soybean varieties were significantly (P<0.05) increased, yet the yield and NR activity were significantly decreased under 50% shading. Based on the constructed comprehensive membership function value, it was found that Huaixian17-08, Kaixian No. 3, Huaixiandou No. 5 and Cuilyuyu had stronger shade tolerance, and were suitable for intercropping with high stem crops.

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Response of grain yield and quality of high quality rice to climate factors at different sowing dates in southeastern Zhejiang Province, China

MA Yihu, ZENG Xiaoyuan, HE Xianbiao, ZHOU Naidi, CHEN Jian

2023, 35(4): 736-751. DOI: 10.3969/j.issn.1004-1524.2023.04.02

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To determine the suitable sowing dates for high quality rice of different types in Southeastern Zhejiang, a field interval sowing experiment was carried out with indica-japonica hybrid rice Yongyou 1540 and indica hybrid rice Tailiangyou 217. The effects of different sowing dates (Ⅰ-Ⅴstage) on grain yield and its components, growth period, seedling quality, tillering characteristics, population growth rate, dry matter accumulation, and rice quality were studied, and the correlation between grain yield and climatic factors, quality and climatic factors was analyzed. The results showed that the grain yield of Yongyou 1540 and Tailiangyou 217 increased first and then decreased with the delay of sowing date, and the yield potential was 11.54 t·hm^-2 for Yongyou 1540 in stage Ⅱ and 9.47 t·hm^-2 for Tailiangyou 217 in stage Ⅲ. The change trend of yield components was basically consistent with the yield change. The growth stages of rice were delayed with the delay of sowing date. Sowing-heading period was shortened, whereas heading-maturing stage was extended, and the change of whole growth period varied with cultivars. With the delay of sowing date, the seedling quality, dry matter accumulation, and harvest index increased first and then decreased, while the tiller number increased and the productive tiller percentage decreased, and the population growth rate and the output rate of dry matter of stem and leaf varied with cultivars and growth stages. The sowing date mainly affected the rice milling and appearance quality. Rice quality was improved with the delay of sowing date. The grain yield was significantly or extremely significantly positively correlated with the resources of temperature and sunshine during the full heading-maturing stage, while the quality was closely related to temperature and sunshine resources from the 20th day after full heading to maturing stage. We recommend the best sowing date for Yongyou 1540 could be from May 7 to May 26. The sowing date for Tailiangyou 217 with high yield and relatively high quality could be from May 16 to May 22, while the sowing date for Tailiangyou 217 with high quality and relatively high yield could be from May 23 to May 27.

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Effects of low temperature on seedling growth at sesame early seedling period and screening of low-temperature tolerant materials

ZHAO Yunyan, SUN Jian, LIANG Junchao, WANG Zhiqi, YAN Tingxian, YAN Xiaowen, WEI Wenliang, LE Meiwang

2023, 35(4): 752-768. DOI: 10.3969/j.issn.1004-1524.2023.04.03

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To study the effects of temperature on the growth and development of sesame seeds at the early seedling period, and analyze the physiological response to low temperature stress during sesame early seedling period and the differences in the responses of different genotypes of germplasm resources to low temperature stress. In this study, 5 sesame germplasms with different temperature sensitivities were used as the test materials, 5 treatment temperatures (28, 25, 21, 18, 15 ℃) were set for dark culture treatment, the root length, shoot length and seedling fresh weight were measured and analyzed to determine the sensitive temperature for low temperature stress during the early seedling preiod. The low-temperature tolerance of 188 sesame germplasm resources was evaluated by correlation analysis, membership function value and cluster analysis. In addition, we determined the physiological and biochemical indexes of different genotypes materials under low temperature tress at early seedling period. The results showed that with the decrease of temperature, root length, shoot length and fresh weight of sesame at early seedling stage showed a gradual downward trend, which decreased significantly at 18 ℃. The 188 sesame germplasm materials were clustered into 5 groups by cluster analysis, including 5 highly low-temperature resistant materials, 42 low-temperature resistant materials, 44 intermediately low-temperature resistant materials, 50 low-temperature intolerant materials and 47 extremely low-temperature intolerant materials. The results of geographical classification showed that there were certain differences in the low-temperature tolerance of test materials from different geographical sources, among which the low-temperature tolerance richness of central Jianghuai region was large. Under low temperature stress at early seedling stage, the physiological indexes of different genotypes of sesame shoot and root increased to different degrees, such as contents of H₂O₂, MDA, proline, soluble sugar and soluble protein, among which H₂O₂ and MDA contents increased significantly, and CAT and SOD activities increased. 5 highly low-temperature tolerant germplasm resources were screened out, such as Zhuzhi19 and Luozhi16, so as to lay a foundation for the exploration of low-temperature resistant sesame germplasm resources and the breeding of new varieties.

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Effects of nitrogen on physiological growth, quality and yield of weak gluten wheat after rice stubble

REN Kaiming, WANG Ben, YANG Wenjun, FAN Yonghui, ZHANG Wenjing, MA Shangyu, HUANG Zhenglai

2023, 35(4): 769-779. DOI: 10.3969/j.issn.1004-1524.2023.04.04

Abstract ( 378 )

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To explore suitable nitrogen application levels for weak gluten wheat after rice stubble in Anhui Province’s Huaihe River region, a field experiment was conducted using 5 nitrogen application levels (0, 75, 150, 225, and 300 kg·hm^-2). The study investigated the effects of nitrogen application on yield, quality, dry matter accumulation and transport, and nitrogen use efficiency of wheat. The results showed that in the range of 0-300 kg·hm^-2 nitrogen application level, with the increase of nitrogen application, the number of tillers, plant height, leaf area index (LAI) and chlorophyll relative content (SPAD) of wheat showed an upward trend. 21 days after anthesis, the spectral reflectance of wheat canopy gradually increased in the band of 760-925 nm, and first increased and then decreased in the band of 925-1 300 nm. From booting to maturity, dry matter accumulation and transport of pre-anthesis vegetative organs increased initially then declined with increasing nitrogen application level, the contribution rate of dry matter transport of pre anthesis vegetative organs to grains continued to decline, while the post anthesis dry matter production and its contribution rate to grains gradually increased. The number of grains per ear and effective ears increased with increasing nitrogen application level, the 1 000 grain weight and grain yield of wheat showed a trend of increasing first and then decreasing, reaching maximum grain yield at 225 kg·hm^-2 nitrogen application level. Compared with the treatment without nitrogen application, grain yields at location I and II increased by 127.58%-230.45% and 72.21%-131.94% when nitrogen application level was 75-300 kg·hm^-2. As the nitrogen application level increased, the apparent utilization rate, agronomic utilization rate, and partial productivity of nitrogen fertilizer gradually decreased. The wheat grain quality index was better at a nitrogen application level of 225 kg·hm^-2, but when the nitrogen application level was 300 kg·hm^-2, the wheat grain protein content exceeded the national protein content standard of weak gluten wheat. Compared to the treatment without nitrogen application, the wheat grain protein content increased by 12.02%-44.21% and 9.64%-34.30% at the two test points when the nitrogen application level was between 75-300 kg·hm^-2. Overall, when the nitrogen application level was 225 kg·hm^-2, the wheat grain quality index was better, and the yield was the highest. Considering the selection criteria of high yield and high quality, 225 kg·hm^-2 was identified as the suitable nitrogen application level for weak gluten wheat in the rice stubble region along the Huaihe River in Anhui Province.

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OsPUT5 silencing reduced low temperature resistance in rice

ZHANG Bin, FENG Xiaoqing, ZHENG Qian, CHEN Wen, TENG Jie

2023, 35(4): 780-788. DOI: 10.3969/j.issn.1004-1524.2023.04.05

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In order to study the function of polyamine uptake transporters (PUT) in rice, the members of OsPUT family in rice were identified by bioinformatics methods, and the structure of OsPUT5 protein was analyzed. The expression of OsPUT5 gene in different tissues of rice was detected by qRT-PCR, and the function of OsPUT5 gene was preliminarily studied by using rice overexpress (OE) lines, Nipponbare (Nip) lines and RNAi lines. The results showed that there were 6 OsPUTs in rice, among which, OsPUT5 was a membrane protein with 10 transmembrane domains and with the unique domain of putrescine ornithine antiporter PotE, it’s N-terminal and C-terminal were located outside the membrane. The gene expression pattern showed that OsPUT5 gene had the highest expression in leaves, but there was no significant(P>0.05) difference among roots, stems and flowers. In the life cycle, under normal conditions, there was no obvious phenotypic difference among RNAi lines, Nip lines and OE lines. At the seedling stage of rice, the relative conductivity, malondialdehyde content and proline content of RNAi lines, Nip lines and OE lines were significantly (P<0.05) increased after treatment at 4 ℃ for 30 h. Moreover, phenotypes were affected, compared with Nip lines and OE lines, RNAi lines were most affected, with withered leaves, serious water lost, significantly (P<0.05) reduced plant fresh weight and proline content, and significantly (P<0.05) increased relative conductivity and malondialdehyde content. Normal culture for 10 days after cold stress treatment, the survival rate of RNAi lines was significantly (P<0.05) lower than that of Nip lines and OE lines. It showed that overexpression or inhibition of OsPUT5 gene expression had no significant effect on the normal growth and development of rice, but inhibition of OsPUT5 gene expression reduced the resistance of rice to cold stress.

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Effects of different exogenous substances on pollen germination and pollen tube growth of Camellia oleifera

XU Jinming, CHANG Yihong, GONG Han, GONG Wenfang, YUAN Deyi

2023, 35(4): 789-798. DOI: 10.3969/j.issn.1004-1524.2023.04.06

Abstract ( 440 )

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Camellia pollen was used as the material to study the effects of different substances of plant growth regulators, mineral elements, compound NO and reactive oxygen species (ROS) on pollen germination and pollen tube growth, and the orthogonal method was used to optimize the culture components of C. oleifera pollen germination. The results showed that 0.5-5.0 mg·L^-1 gibberellic acid (GA₃) and 0.5 mg·L^-1 naphthylacetic acid (NAA) could significantly promote pollen germination and pollen tube growth, and the maximum pollen germination rates were 59.07% and 71.29%, respectively. However, at high concentration (50 mg·L^-1), NAA and GA₃were significantly inhibited pollen germination and pollen tube growth. The germination rate of C. oleifera pollen treated with 10-50 mg·L^-1 MgSO₄ ranged from 56.88% to 65.83%, the maximum pollen tube length was 2 809.56 μm at 24 h. The promoting effect of 50-150 mg·L^-1 CaCl₂·2H₂O was significantly different from that of the control group, and the germination rate ranged from 59.91% to 63.28%, the maximum pollen tube length was 2 770.11 μm at 24 h. The pollen germination rate and pollen tube length decreased with increasing concentrations of ethylene glycol tetraacetic acid (EGTA) (inhibitor of Ca²⁺), ethephon and sodium nitroprusside (SNP) (donor of NO). 100-300 μmol·L^-1 Nω-Nitro-L-arginine (L-NNA) (NO inhibitor) promoted pollen germination and pollen tube growth, and the maximum pollen germination rate was 68.12%. The higher the concentration of H₂O₂(ROS donor) and N-Acetyl-L-cysteine (NAC) (ROS inhibitor), the lower the pollen germination rate and pollen tube length, and the maximum pollen germination rates were 48.39% and 45.78%, respectively. The results of orthogonal experiments showed that the optimal composition for promoting C. oleifera pollen germination were 100 g·L^-1sucrose, 10 g·L^-1 agar, 0.1 g·L^-1 H₃BO₃, 50 mg·L^-1 CaCl₂·2H₂O, 10 mg·L^-1 MgSO₄, 0.5 mg·L^-1 NAA and 2 mg·L^-1 GA₃, and the optimal composition for promoting C. oleifera pollen tube growth were 100 g·L^-1sucrose, 10 g·L^-1 agar, 0.1 g·L^-1 H₃BO₃, 50 mg·L^-1 CaCl₂·2H₂O, 10 mg·L^-1 MgSO₄, 0.5 mg·L^-1 NAA and 8 mg·L^-1 GA₃. Ca²⁺, Mg²⁺ and appropriate concentrations of GA₃and NAA promoted pollen germination and pollen tube growth, while ethylene, NO and ROS had opposite effects. This paper can lay the foundation for the in vitro germination test of C. oleifera pollen.

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Analysis of GRM1 gene polymorphism and its correlation with meat quality traits in sheep

NIE Wei, MENG Ke, RONG Xuan, QIANG Hao, GUO Chenhao, TAO Maohai, FENG Dengzhen

2023, 35(4): 799-808. DOI: 10.3969/j.issn.1004-1524.2023.04.07

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To investigate the polymorphism of metabotropic glutamate receptor 1 gene (GRM1) in sheep and its effect on meat quality traits, with a view to providing effective genetic molecular markers for the breeding of sheep for meat performance. The GRM1 gene was sequenced in 91 sheep from three sheep populations, Tan sheep (T), Little-tailed Han sheep (XH), and Dorper sheep (D), using liquid-phase capture sequencing technology. The genotypes of the genotyped loci were analyzed by flight mass spectrometry for the meat quality traits of the Tan sheep (T), Little-tailed Han sheep (XH), Dorper sheep (D) and Dutanhan sheep (DTH). The results showed that there were significant differences in meat quality traits among the different genotypes of sheep. Sheep kidney mass with CT genotype was significantly (P<0.05) greater than that with TT genotype at the rs415006419 locus of the GRM1 gene, and tyrosine content in muscle of sheep with TT genotype was significantly (P<0.05) higher than that with CT genotype; Sheep live weight before slaughter, carcass weight, net meat weight, duodenal length, and heart, lung and kidney mass with TT genotype at locus rs403075278 of the GRM1 gene were significantly (P<0.01) greater than those with the CT genotype, and backfat thickness, net meat weight, spleen mass, muscle fat, calcium content, phenylalanine and histidine content with TT genotype were significantly (P<0.05) higher than those with CT genotype. pH, shear and water loss with CT genotype were significantly (P<0.01) greater than those with TT genotype. The remaining slaughter performance, meat quality and muscle nutrient content were not significantly (P>0.05) different between the two genotypes. The above results suggest that GRM1 gene could be used as a candidate gene for meat quality traits in sheep, rs415006419 and rs403075278 loci could be used as potential candidate genetic markers for sheep growth and development, and meat production performance.

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Optimization of water-nitrogen coupling scheme for production effect of cucumber in sand culture in greenhouse

MA Xinchao, XUAN Zhengying, TAN Zhanming, ZHOU Yu, WANG Xufeng

2023, 35(4): 809-820. DOI: 10.3969/j.issn.1004-1524.2023.04.08

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In order to explore the effects of water and nitrogen coupling on the growth, yield, quality and water and nitrogen utilization of sand-cultured cucumber, a water and nitrogen management scheme for high-yield, high-efficiency and high-quality production of sand-cultured cucumbers was formulated. In this study, the Youshengmei fruit cucumber was used as the test material to carry out the water-nitrogen coupling experiment of the sand cultured cucumber. In this experiment, two factors of irrigation level and nitrogen application rate were set, and the quadratic saturated D-optimal design was adopted. The results showed that there were significant differences in growth, yield, quality, water use efficiency and nitrogen use efficiency of each treatments, which were affected by irrigation level, nitrogen application rate and its coupling effect in varying degrees. When the upper limit of irrigation was in the range of 65.00%-89.40%, and the amount of nitrogen application was in the range of 623-1 250 kg·hm^-2, the growth of plant was better. In sand culture, the amount of nitrogen application was the key factor to determine the yield of cucumber. Increasing nitrogen application could significantly increase the yield, while excessive nitrogen application and irrigation level would reduce the yield, which conformed to the law of diminishing returns. Higher water use efficiency could be obtained by increasing nitrogen fertilizer and reducing irrigation level. Excessive application of nitrogen fertilizer and too low irrigation level would lead to the decline of nitrogen use efficiency and quality. Under the experimental conditions, the optimal water nitrogen coupling scheme was: the irrigation level was 79.12% (i.e. the upper and lower limits of irrigation with 60.00%-79.12% of the field capacity of the substrate) and the nitrogen application rate was 1 100 kg·hm^-2. Under this scheme, the plant grew healthily and could achieve the goal of high-yield, high-efficiency and high-quality agricultural production, which could provide a theoretical basis for the scientific and refined management of water and nitrogen of sand-culture cucumber.

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Analysis on codon usage patterns of chloroplast genome of Lonicera japonica cv. Damaohua

ZHANG Jiaqiang, LIU Huichun, WANG Jie, XU Wenting, ZHOU Jianghua, ZHU Kaiyuan

2023, 35(4): 821-830. DOI: 10.3969/j.issn.1004-1524.2023.04.09

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By analyzing the codon usage bias of the chloroplast genome of Lonicera japonica cv. Damaohua, we explored the main factors affecting the formation of its codon bias, and provided references for the study of the phylogeny of Lonicera japonica and the evolution of codons in the chloroplast genome. The codon usage bias of 50 chloroplast protein-coding genes of Lonicera japonica cv. Damaohua were analyzed using the bioinformatics software. The GC content of the chloroplast genome of Lonicera japonica cv. Damaohua was 39.18%, the ENc value was 48.81, and the bias for codon usage was weak. The correlation coefficient of GC and GC1, GC2, GC3, GC3s, GC and CAI all reached significant or extremely significant levels. There were 30 codons with RSCU values greater than 1, of which, 28 condons ending with A and T. Comprehensive ENc-plot analysis, PR2-plot analysis, neutral plot analysis and correspondence analysis showed that during the formation of codon usage bias in the chloroplast genome of Lonicera japonica cv. Damaohua, selection pressure and mutations and other factors played an important role together. Based on the analysis of relative synonymous codon usage, 30 high-frequency codons and 5 optimal codons were determined, the optimal codons all ended with A or T. This study clarified that the codon usage bias of the chloroplast genome of Lonicera japonica cv. Damaohua was jointly affected by factors such as selection pressure and mutation, and screened out five optimal codons.

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Cloning, expression and bioinformatics analysis of BrrLOX7 gene in turnip

YAN Cunyao, JIA Kai, YAN Huizhuan, GAO Jie

2023, 35(4): 831-840. DOI: 10.3969/j.issn.1004-1524.2023.04.10

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Lipoxygenase (EC 1.13.11.12; LOX) is a class of fatty acid dioxygenases composed of non-heme iron, which plays an important role in plant growth and development and environmental stress response. In this study, the BrrLOX7 gene was cloned from turnip using homologous cloning techniques. The sequence of BrrLOX7 gene was analyzed by bioinformatics. The expression pattern of BrrLOX7 gene under abiotic stress was analyzed using fluorescence quantitative PCR. The results showed that the CDS length of cloned BrrLOX7 gene was 2 715 bp, it encoded 904 amino acids, protein encoded by BrrLOX7 gene had a relative molecular weight of 103.10 ku and had no transmembrane structure or signal peptide. Subcellular localization prediction showed that the protein encoded by this gene was located in chloroplasts, and the protein had the closest sequence homology and genetic distance to Chinese cabbage and radish. Expression patterns under different stresses showed that the BrrLOX7 gene was involved in response to four stresses (salt stress, cold stress, heat stress and drought stress). The results of this study will provide a basis for functional studies of the BrrLOX7 gene.

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Effects of plant growth regulators on growth characteristics and turf quality of bermudagrass

DENG Peichao

2023, 35(4): 841-852. DOI: 10.3969/j.issn.1004-1524.2023.04.11

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To provide theoretical basis for the expansion of bermudagrass vegetations, Cyndon dactylon × C. trasvalensis cv. Tifsport was used as the material to study the effects of different concentrations of growth regulators (antitransexate, chlormequat, paclobutrazol, diquat, ethephon and gibberellin) on the growth characteristics and turf quality of bermudagrass. The results demonstrated that according to the subordinate function, the recommended application concentrations of the plant growth regulators were as follows: 2.0 kg·hm^-2 of trinexapac-ethyl, 2.0 kg·hm^-2 chlormequat chloride, 0.5 kg·hm^-2 paclobutrazol, 0.1 kg·hm^-2 diquat, 2.0 kg·hm^-2 ethephon and 0.02 kg·hm^-2 gibberellin. At the recommended application concentration of each plant growth regulator, except diquat treatments (applied at 0.1 kg·hm^-2 caused 15.3% of damage rate), the other five plant growth regulators did not cause damage at the recommended concentrations. Paclobutrazol did not affect the leaf color (the leaf color score was still more than 7.0). Compared with the control, the height and leaf length were significantly reduced by the application of trinexapac-ethyl, chlorocholine chloride, paclobutrazol and ethephon (the decline rate was more than 20%). The number of stolons had no significant change by application of ethephon at all concentrations, but diquat and gibberellic acid could significantly reduce the number of stolons. Diquat was not suitable as a growth inhibitor to control the growth of bermudagrass. Application at 2.0 kg·hm^-2 trinexapac-ethyl inhibited the stolon and internode length showed and no effect on the stolon number and turf quality of bermudagrass.

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Ecological response of organic acid metabolism of Huangguogan fruits at different altitudes

WU Jiao, GONG Chengyu, CHEN Chaoqun, CHEN Hongxu, LIU Junhong, TANG Wenjing, CHU Yuanqi, YANG Wenlong, ZHANG Yao, GONG Ronggao

2023, 35(4): 853-861. DOI: 10.3969/j.issn.1004-1524.2023.04.12

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To reveal the relationship between Huangguogan fruit organic acid accumulation and different altitudes in the dry and warm valley of Dadu River, seven-year-old Huangguogan with altitudes of 875 m, 1 014 m and 1174 m were selected on the same mountain to study the changes of organic acid metabolism related indicators during fruit development. The results showed that the fruit organic acid was mainly citrate acid, accounting for more than 75%, followed by malic acid and quinic acid; the citric acid content was largely degraded in the later stage, and the higher the altitude, the lower the citric acid content; as the altitude increased significantly enhanced the cytoplasmic ACO activity and NADP-IDH activity in the citric acid degradation stage of the fruit. At the same time, the increase of altitude started ACO gene expression and increased NADP-IDH gene expression in advance.The difference in fruit organic acid content between different altitudes depended on the degradation of citric acid in the middle and late stages of fruit development; the main enzymes that caused the difference in organic acid content between different altitudes were cytoplasmic ACO, NADP-IDH and PEPC. Increased altitude might increase the activity of cytoplasmic ACO and NADP-IDH by activating ACO gene expression in advance and increasing NADP-IDH gene expression to promote the degradation of citric acid in fruit.

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Correlation between capsaicin content and agronomic traits in pepper (Capsicum annuum L.) germplasm resources

ZHU Li, XUE Xinru, LIANG Zongxu, XU Linyu, YU Guofeng, TANG Yi, LI Huanxiu

2023, 35(4): 862-872. DOI: 10.3969/j.issn.1004-1524.2023.04.13

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In order to make full use of pepper resources and study the content of capsaicin in different pepper germplasm resources and its correlation with other agronomic traits, the capsaicin content and 24 agronomic traits of 54 collected pepper resources were measured, and the correlation between capsaicin content and agronomic traits was explored by coefficient of variation and correlation analysis. The results showed that the distribution of capsaicin and dihydrocapsaicin in different pepper fruits was basically same, and the content of capsaicin was higher than that of dihydrocapsaicin. The total content of capsaicin varied with fruit development, showing two trends. First, it gradually increased to the highest value with fruit development and slightly decreased at red ripening stage. Second, with fruit development, the total content of capsaicin generally increased and reached to the highest value at red ripening stage. The distribution of spicy grade of pepper fruits with different sizes was different, and the peppers of small fruit type were higher than that of large fruit type. The average coefficient of variation of all traits was 56.16%. The coefficients of variation of pepper fruit surface ridge, single fruit weight, capsaicin content, fruit shoulder shape, fruit transverse diameter, corolla color, style color, fruit section shape and fruit longitudinal diameter were high, and had good genetic variability. There was a significant correlation between the traits of pepper, and the traits significantly correlated with the longitudinal diameter of fruit were the most, up to 12. The contents of capsaicin in young fruit stage, green ripening stage and red ripening stage were negatively correlated with fruit shoulder shape, single fruit weight, fruit longitudinal diameter, fruit transverse diameter and pulp thickness at P<0.05 or P<0.01. The research results could laid a foundation for the breeding of new varieties of pepper with high spiciness and high content of capsaicin, and provide reference for pepper production and planting plan.

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Studies on isolation and identification of antagonistic bacteria against tobacco root black rot pathogen, Thielaviopsis basicola and their biocontrol characteristics

HUANG Wanyuan, LI Caibin, PENG Yu, LI Zhanghai, HUANG Yanzhang, DING Ting

2023, 35(4): 873-883. DOI: 10.3969/j.issn.1004-1524.2023.04.14

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In order to explore the biocontrol bacteria resources which had the strong antagonistic effect on tobacco black root rot and could stably colonize the tobacco roots, taking Thielaviopsis basicola as the target, the highly antagonistic strains were isolated and obtained by dilution-plate method and plate confrontation method, and the phylogenetic analysis and antibacterial activity of crude lipopeptide of antagonistic strains were carried out; then the genes coding lipopeptide of antagonistic strains were analyzed by PCR, the effects of K326 tobacco root exudates and various organic acids on root colonization of antagonistic bacteria were studied by chemotaxis and biofilm formation tests. Results indicated that the effective antagonistic strains S2-1 and SNSY15-5 were isolated from tobacco rhizosphere soil, and they were Bacillus microorganisms. The crude lipopeptides of the S2-1 and SNSY15-5 were high virulent to Thielaviopsis basicola, and the EC₅₀ of them was 1.93 and 2.56 mg·mL^-1, respectively. SNSY15-5 had the biocontrol marker genes involved in the synthesis of bmyB, bioA and yngG, while S2-1 had the biocontrol marker gene involved in the synthesis of bioA. Malic acid produced by K326 root exudates had better attraction to S2-1 and SNSY15-5, and the amount of S2-1 and SNSY15-5 in malic acid reached 63.35×10⁴ CFU·mL^-1 and 42.35×10⁴ CFU·mL^-1, respectively. The biofilm formation of S2-1 could be promoted by the K326 root exudates and oxalic acid, while the biofilm formation of SNSY15-5 could be promoted by the K326 root exudates and citric acid. The research results provide a theoretical basis for developing microbial agent with stable effect.

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Biological characteristization of a new pest attacking Agrocybe aegerita: Bradysia peraffinis Tuomikoski 1960 (Diptera, Sciaridae)

WANG Yunping, HE Peishan, MA Jiping, ZHONG Guoxiang, WANG Suzhen, XIAO Yinrun, XIONG Xiaowen, ZHANG Cheng

2023, 35(4): 884-892. DOI: 10.3969/j.issn.1004-1524.2023.04.15

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In recent years, we discovered a species of insects that harmed the Agrocybe aegerita during its cultivation in Jiangxi Academy of Agricultural Sciences. Samples of adults were collected from the culture materials of Agrocybe aegerita, and molecular identification was carried out by amplifying the mitochondrial COⅠ gene and sequence comparison. The neighbor-joining method was used to construct phylogenetic trees. At the same time, we filmed and photographed the insect and described the main morphological characteristics of its eggs, larvae and adults. In addition, their biological characteristics were observed and recorded by raising them in an incubator. The results showed that the insect that harmed Agrocybe aegerita was Bradysia peraffinis Tuomikoski 1960, a new record species in Jiangxi, the similarity with Bradysia peraffinis COⅠ sequence (accession number: JQ613799) reached 99.85%. The larvae of this insect harm hyphae and fruit bodies. And we found the mature larvae crawled to the mouth of the culture bag and pupated, and flew out of the bag after eclosion. Adults were good at flying, with phototaxis. In laboratory tests, their generation period was about 20-29 days in the incubator. It had sevaral generations a year and the generations overlap. This article laid the foundation for the in-depth study of its occurrence and prevention and control techniques in the future.

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Comprehensive evaluation of rape straw biochar as slow-release carrier under different preparation conditions

XU Yang, REN Yilin, WANG Haojie, HUANG Qiuhang, XING Boyuan, CAO Hongliang

2023, 35(4): 893-902. DOI: 10.3969/j.issn.1004-1524.2023.04.16

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In order to quantitatively evaluate the potential of rape straw biochar as a slow-release carrier, high-temperature cracking method was adopted to prepare biochar under different phosphoric acid volume fractions (5%, 10%, 15%), pyrolysis temperature (450, 550, 650 ℃) and holding time (40, 80, 120 min). The surface morphology, functional group composition and physicochemical properties of the prepared biochar were investigated. Then, a grey correlation method was introduced to comprehensively assess the potential of the prepared biochar as a slow-release carrier. The results showed that with the increase of phosphoric acid volume fraction, pyrolysis temperature and holding time, the carbon yield, water content and volatile fraction gradually decreased, while the contents of ash and fixed carbon increased. Based on the results of grey correlation analysis and the influences of phosphoric acid volume fraction, pyrolysis temperature and holding time on biochar yield, the biochar prepared under the conditions when the phosphoric acid volume fraction was 10%, the pyrolysis temperature was 450 ℃, and the holding time was 80 min, had the maximum potential to be used as a slow-release carrier.

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Effects of straw mulching and green manure planting on nitrogen and phosphorus runoff loss in hilly tea garden

YU Qiaogang, JIANG Mingbei, SUN Wanchun, HUANG Zhengchen, WANG Feng, WANG Qiang, MA Junwei

2023, 35(4): 903-912. DOI: 10.3969/j.issn.1004-1524.2023.04.17

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In the present study, the characteristics of nitrogen and phosphorus nutrient loss in hilly tea gardens in southern China, which was represented by Qiandaohu Reservoir area, and the effects of green manure (Vulpia myuros) planting and straw mulching on soil nitrogen and phosphorus runoff loss were studied by natural rainfall and runoff monitoring experiment. The results showed that the water runoff mainly occurred from January to September, and the water runoff was relatively larger from March to July. The highest nitrogen and phosphorus losses were recorded in June. Compared with the convensional mode, straw mulching and green manure planting significantly (P<0.05) reduced the amount of runoff water by 51.4% and 62.0%, respectively, and soil sediment loss by 63.6% and 75.8%, respectively. Nitrate nitrogen was the main form of inorganic nitrogen loss, and total nitrogen loss was higher than total phosphorus loss in the tea garden runoff. Compared with the conventional mode, straw mulching and green manure planting significantly (P<0.05) reduced the amount of ammonium nitrogen loss in runoff water by 68.6% and 79.4%, respectively, nitrate nitrogen loss by 66.2% and 75.8%, respectively, total nitrogen loss by 63.4% and 75.9%, respectively, total phosphorus loss by 60.7% and 72.2%, respectively.Besidess, straw mulching and green manure planting could enhance soil fertility and increase tea yield, thus is suitable for the ecological environment protection of tea garden in the hilly areas of southern China.

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Evaluation on rural environment governance modernization level: year of 2019 as an example

ZHANG Wanjun, ZHU Lizhong, CHEN Dingjiang, WU Donglei, WANG Feier, ZHANG Qingyu

2023, 35(4): 913-921. DOI: 10.3969/j.issn.1004-1524.2023.04.18

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From three dimensions of living environment, ecological environment and assurance system, 19 indexes were selected to construct an evaluation index system for rural environment governance modernization level. The indexes weights were determined by the Analytic Hierarchy Process (AHP) and Delphi method, and the indexes values were determined by the efficacy coefficient method. Based on the data of 1 818 county-level administrative districts in 2019, the modernization level of rural environment governance was evaluated. The results showed that the modernization level of rural environment governance of China at county level belonged to the general level, with an average value of 0.350. The county-level administrative districts, which reached the excellent level, were mainly distributed in the eastern region. There were large regional differences in the modernization level of rural environment governance in China. The living environment in the western region was weak. The main restricting dimension in all regions was the assurance system. Based on these findings, suggestions were put forward, such as establishing a mutual assistance and cooperation mechanism and a long-term infrastructure operation and management mechanism to promote the coordinated development of rural environment governance modernization level in different regions, and strengthening the assurance system and mechanism to make up for the shortcomings of the modernization level of rural environmental governance.

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Effect of organic-inorganic compound fertilizer on wheat growth, nutrients and heavy metal content of soil and wheat

LU Shuai, LUO Xiaogang, LIU Quanwei, ZHANG Yi, MENG Yanghao, LI Jie, ZHANG Jinglai

2023, 35(4): 922-930. DOI: 10.3969/j.issn.1004-1524.2023.04.19

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To investigate the effect of organic-inorganic compound fertilizer on wheat growth, nutrients and heavy metal content of soil and wheat, Hebei winter wheat was used to conduct the field experiments. Six treatment groups were set up in this experiment: CK (without fertilizer), FP (regular fertilizer), SJ40 (600 kg·hm^-2 organic-inorganic compound fertilizer+225 kg·hm^-2urea as additional fertilizer), SJ60 (900 kg·hm^-2 organic-inorganic compound fertilizer+225 kg·hm^-2urea as additional fertilizer), SJ80 (1200 kg·hm^-2 organic-inorganic compound fertilizer+225 kg·hm^-2urea as additional fertilizer), SJ40+30 (600 kg·hm^-2 organic-inorganic compound fertilizer+450 kg·hm^-2 organic-inorganic compound fertilize as additional fertilizer). Results showed that wheat yield gradually increased with the increase amount of organic-inorganic compound fertilizer and reached a maximum of 9.26 t·hm^-2, inorganic nitrogen, effective phosphorus, fast-acting potassium and organic matter content in the soil showed an increasing tendency compared with the control group. The use of organic-inorganic compound fertilizers also significantly reduced the contents of Cd and Pb in wheat grain, with maximum reductions of 28.8% and 30.3%, respectively. In conclusion, the rational use of organic-inorganic compound fertilizers could increase wheat yield, improve soil properties, and reduce the content of heavy metals in wheat, which had great application prospects in agricultural production.

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Analysis for accumulation of norisoprenoids and changes of metabolic enzyme activities of Chardonnay grape berries

ZHANG Zhen, CUI Yuanyuan, CHEN Chunxia, FENG Lidan, ZHAO Yong, LI Jixin, BA Lingzhen, KONG Xiangjin, ZHANG Yu, JIANG Yumei

2023, 35(4): 931-941. DOI: 10.3969/j.issn.1004-1524.2023.04.20

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In order to determine the pattern of production and accumulation for norisoprenoids of Chardonnay grape berries, samples were collected every 2 weeks from young grapes (10 days after flowering) to maturity (80 days after flowering) in two consecutive production seasons in 2020 and 2021. The titratable acidity, pH, soluble solids, 100-grain weight, total carotenoids, norisoprenoids and carotenoid cleavage dioxygenase (CCD) enzyme activity were measured, and their change pattern were analyzed during the growth, and the correlation among carotenoids, CCD enzyme activity and norisoprenoids was discussed. The results showed that 6 norisoprenoids were determined during the growth. The total content of norisoprenoids showed an upward trend with the fruit ripened. CCD enzyme activity tended to increase in young fruits (10-38 days after flowering), to decrease in veraison (38-52 days after flowering), and to increase in fruits ripening stage (52-80 days after flowering). The total carotenoid content showed an overall decreasing trend, but there was a small accumulation peak before or after the veraison. The correlation analysis showed that CCD enzyme activity was negatively correlated with total carotenoid content, and positively correlated with free and bound α-ionone, β-ionone, β-damascenone, free geranylacetone, and bound 6-methylhept-5-en-2-one. Comparison of samples from different production seasons found that the climate of the production season had an effect on the physicochemical index, total carotenoid content, CCD enzyme activity and the content of norisoprenoids in the berries.

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Residue behavior and dietary exposure risk assessment of azoxystrobin in waxberry

ZHANG Chunrong, GUO Qian, KONG Liping, WU Yuanyuan, LIN Qin, XU Zhenlan, ZHAO Xueping, TANG Tao

2023, 35(4): 942-951. DOI: 10.3969/j.issn.1004-1524.2023.04.21

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In order to clarify the residual characteristic and dietary risk of azoxystrobin in waxberry, an analytical method was developed for the determination of azoxystrobin residues in waxberry by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the storage stability of azoxystrobin in waxberry was also investigated. The field trials of 50% water dispersible granule of azoxystrobin were conducted in six provinces in the year of 2018. The samples were extracted by acetonitrile, purified by alkaline alumina and quantified by external standard method. The results showed that the calibration curve with good linearity was obtained in the concentration range from 0.001 to 0.05 mg·L^-1, with correlation coefficients (R²) not less than 0.999 1. At the spiked levels of 0.01 to 30.0 mg·kg^-1, the average recovery of azoxystrobin in waxberry was 90%-98% with relative standard deviations (RSD) of 1.8%-7.9%. The limit of quantitation (LOQ) of azoxystrobin in waxberry matrix was 0.01 mg·kg^-1. The degradation rates of azoxystrobin in waxberry samples with initial concentration of 5 mg·kg^-1 were lower than 14.3% at no more than -18℃, indicating that azoxystrobin can be steadily stored for at least 650 days in waxberry samples. The dissipation dynamics of azoxystrobin was fitted to the first-order kinetics equation, and the half-lives of azoxystrobin in waxberry were 2.2-5.0 d, indicating azoxystrobin was an easily degradable pesticide (T_1/2<30 d). 50% azoxystrobin water dispersible granule was sprayed twice with an interval of 10 d at the recommended high dosage (300 mg·kg^-1) in the waxberry. The final residues of azoxystrobin in the waxberry were 0.012-0.57,<0.010-0.52,<0.010-0.28 mg·kg^-1 at day 20, 25 and 30 after application, respectively, which were lower than the maximum residue limits of azoxystrobin in berry and other small fruits. The long-term dietary intake risk assessment indicated that the national estimated daily intake (NEDI) of azoxystrobin was 6.111 4 mg, with a risk quotient (RQ) of 48.5%. The results showed that the residual levels of azoxystrobin in waxberry did not pose unacceptable risks to the general population.

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Study on extraction method of soybean planting areas based on unmanned aerial vehicle RGB image

ZHANG Meng, SHE Bao, YANG Yuying, HUANG Linsheng, ZHU Mengqi

2023, 35(4): 952-961. DOI: 10.3969/j.issn.1004-1524.2023.04.22

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A typical fragmented farmland in Taihe County, Fuyang City, which is located in the main soybean producing area in the northern Anhui Province, China, was taken as the study area in the present study. Soybean planting area extraction models were constructed based on the unmanned aerial vehicle (UAV) RGB images and different machine-learning algorithms to perform fine crop mapping. In addition to the relative reflectances of R, G, B bands, the 3 components of HLS color space, 9 visible light vegetation indices, 6 texture features and 1 geometrical feature, were selected as the candidate feature variables. Then, a feature selection method coupled with classifier was employed to single out four optimum feature-subsets for the algorithms of random forest (RF), support vector machine (SVM), extreme gradient boosting (XGBoost) and BP neural network (BPNN). Corresponding models were subsequently constructed based on the filtered subsets of features and algorithms for mapping, and their performances were examined. It was shown that the optimum feature-subsets of the four algorithms outperformed the original RGB bands in terms of extraction accuracy, among which RF exhibited the best performance, as its overall accuracy was 93.96%, and the Kappa coefficient reached 0.87. In general, the RF algorithm combined with optimum feature-subset showed great potential in soybean planting area extraction based on UAV platform, and the feature selection method could achieve a balance between higher classification accuracy and less data volume, which had certain practical significance.

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Comprehensive evaluation of China’s regional agricultural quality development level based on entropy weight TOPSIS under background of carbon peaking and carbon neutrality goals: from perspective of change speed

ZENG Xiaochun, LI Suicheng, SHI Guanqing, XING Zeyu

2023, 35(4): 962-972. DOI: 10.3969/j.issn.1004-1524.2023.04.23

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Based on the provincial panel data of China from 2015 to 2020, a time series evaluation system on the high-quality development of regional agriculture was constructed under the background of carbon peaking and carbon neutrality goals from aspects of agricultural low-carbon economy, agricultural carbon sequestration, agricultural carbon emission and agricultural carbon sequestration. Besides, a comprehensive evaluation model of regional agricultural high-quality development was constructed from the perspective of change speed through information aggregation. The empirical results showed that the overall change speed of Hebei and Liaoning had a downward trend, while their time series evaluation results were relatively high, which reflected the lack of impetus for subsequent development. Ningxia, Gansu, Guizhou showed relatively lower temporal evaluation value, yet their change speed exhibited an upward trend. Although the current situation of high-quality development of agriculture under the background of carbon peaking and carbon neutrality goals in these regions was not satisfactory, but their development potential was sufficient, which showed the phenomenon of “reverse Matthew effect”. Based on these findings, suggestions were put forward, such as promoting development according to local conditions, paying attention to the follow-up effect, and narrowing the gap between regional high-quality development of agriculture.

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