Table of Content

15 January 2023, Volume 25 Issue 1

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AGRICULTURAL INNOVATION FORUM

Current Situation and Development Suggestion of National Modern Agricultural Industrial Science and Technology Innovation Center

Hui YU, Xianwu LIU

2023, 25(1):  1-5.  DOI: 10.13304/j.nykjdb.2022.0872

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To establish the Science and Technology Innovation Center （STIC） for modern agricultural industry is a major construction for the improvement of agricultural science and technology innovation system in China， which is of great significance for promoting the deep integration of science and technology and economy， accelerating the progress of agricultural science and technology， and realizing the self-reliance and self-improvement of high-level science and technology. This paper summarized the development status and successful experience of the STIC for national modern agricultural industry， analyzed the existing problems， and finally put forward development suggestions from the aspects of improving the achievement evaluation system， increasing the government support， innovating the system and mechanism， and strengthening the publicity and promotion.

Characteristics and Causes of Regional Variation of Grain Production Capacity in China

Huanhuan ZHANG, Guogang WANG, Yongxiang ZHANG, Shuai HAO

2023, 25(1):  6-15.  DOI: 10.13304/j.nykjdb.2022.0156

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Grain production capacity is the key to stabilize regional grain supply and ensure national food security. As food production conditions change， the food production capacity of the country's three major functional food production zones continues to diverge， posing a potential threat to food security in the region. Based on the panel data of 31 provinces （autonomous regions and municipalities） from 2003 to 2020， the study first analyzes the changes and characteristics of grain production capacity in different regions of China from the perspective of per capita grain production and other factors using descriptive statistics， and then further empirically analyzes the causes of regional changes in grain production capacity based on a panel fixed-effects model. The study found that the grain production capacities of three major grain production functional areas showed a trend of polarization， the grain production capacity of non-main production areas tended to be lower， and the level of food security in the region was tight. There were regional differences in the influence of cultivated land area， regional economic development level， and mechanization level on grain production capacity. It was suggested that the main production areas should increase the protection of cultivated land， promote water-saving and other technologies to stabilize the regional grain production capacity； improve the grain support policies for non-main production areas， speed up the process of mechanization of weak links， and increase the enthusiasm for grain production in non-main production areas. Above results provided reference for improving regional grain production capacity and ensuring national food security.

BIOTECHNOLOGY & LIFE SCIENCE

Research Advance on Molecular Physiological Mechanisms of the Effect of Suboptimal Low Temperatures on Plant Growth and Nitrogen Nutrition

Changzheng WU, Wenxuan PU, Song SHENG, Yucheng XIANG, Weiqin YANG, Wenrui LI, Pingjun HUANG, Laihua LIU

2023, 25(1):  16-25.  DOI: 10.13304/j.nykjdb.2021.0896

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Low temperatures at early spring is one of the environmental constrains affecting plant growth. Low-temperature stress results in a severe decrease in the crop yield and quality， as well as the effective utilization of plant nutrients including nitrogen. Relevant studies have focused mostly on the analysis of physiological and molecular regulatory networks of plant growth when temperature was lower than 15 ℃.Exogenous application of certain substances e.g. nitrogen fertilizer or hormone could improve plant cold tolerance， so this article reviewed the influence of the suboptimal temperature on growth phenotype of some major crops， physiological and metabolic change， and nitrogen use， summarized and discussed the biological mechanisms of plant response to the sub-optimum temperature in association with the regulation of nitrogen acquisition and utilization， which was expected to provide reference for future understanding of higher nitrogen use efficiency and its related molecular physiological mechanism under the sub-optimal low temperature.

Research Progress on Influencing Factors of Chicken Core Temperature

Ao ZHANG, Hao BAI, Yulin BI, Yingquan HUANG, Zhixiu WANG, Yong JIANG, Guohong CHEN, Guobin CHANG

2023, 25(1):  26-34.  DOI: 10.13304/j.nykjdb.2021.0892

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With the continuous development of the poultry industry， more and more people pay attention to the health and welfare of poultry. Under the pressure of market demand， the breeding of contemporary poultry breeds increasingly pursue traits such as high efficiency and rapid growth or high yield and fast reproduction， so poultry resistance stress ability and immune performance are continuously declining. Body core temperature is an important indicator to judge the physiological health of chickens. This article focused on the key indicator of chicken body core temperature， expounded the relationship between core temperature and environmental temperature， leisure sleep， eating and drinking， light ventilation and disease monitoring. This article was aimed to analyze the key factors affecting the core temperature and health status of chicken， and to further elucidate the law that could reflect the changes of body core temperature in normal and pathological conditions of chicken. It was helpful to accurately control the health condition of chickens in practical production， and to improve the viability of chickens and to reduce economic losses.

Relationship Between Electrical Conductivity of Seed Soaking Solution and Seed Vigor in Rice （Oryza sativa L.）

Zompur CHU, Guangfeng MAO, Min WU, Hongkai WU

2023, 25(1):  35-41.  DOI: 10.13304/j.nykjdb.2021.0552

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To evaluate the relationship of electrical conductivity （EC） and seed vigor， 23 representative rice varieties were artificially aged at 40 ℃ and 85% relative humidity for 0， 14， 28， 42 and 56 d， respectively， which generated seed samples with an extensive range of vigor level. The relationship between electrical conductivity and seed vigor were analyzed. The results showed that EC of seeds with hull were higher than those of seeds without hull. Compared with the EC of seeds with hull， the EC of seed without hull had a higher correlation with germination rate， germination energy and germination index. However， there was no significant regression relationship between the EC of seed without hull and germination rate， germination energy， germination index， which R² were 0.045 2， 0.026 3 and 0.036 7， respectively. The seed vigor of rice could not be predicted by regression equation of seed vigor with the EC.

Molecular Characterization and Inheritance Stability Analysis of Herbicide-resistant Cotton GV-2

Guoqing LU, Caixia MA, Guoqing SUN, Huiming GUO, Hongmei CHENG

2023, 25(1):  42-49.  DOI: 10.13304/j.nykjdb.2021.0581

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Molecular characterization and inheritance stability are important data for safety evaluation of genetic modified crop in China. The whole genome sequencing was used to analyze the T-DNA insertion site， copy number and flanking sequence of the herbicide-resistant transgenic cotton GV-2. The stability of target gene in three successive generations （T₃~T₅） GV-2 were verified by qRT-PCR （quantitative real time polymerase chain reaction）， Southern hybridization， colloidal gold dipstick and ELISA （enzyme linked immunosorbent assay）. The results showed that the T-DNA in GV-2 was inserted in the form of single copy， and the insertion site was located in 2 092 124~2 092 194 bp on chromosome A06 of upland cotton， resulting in the deletion of 70 bp DNA in the cotton genome. The insertion site and flanking sequence were further confirmed by the specific PCR of the transformant and Sanger sequencing. In addition， the target gene and its expressed protein， as well as the target character could be inherited stably in different generations of transformants. The results provided effective support for safety evaluation of cotton GV-2 transformant.

Functional Analysis of Cytochrome P450 Family GmCYP78A71 in Soybean Nodulation

Zhanwu YANG, Hui DU, Xinzhu XING, Wenlong LI, Youbin KONG, Xihuan LI, Caiying ZHANG

2023, 25(1):  50-57.  DOI: 10.13304/j.nykjdb.2021.0843

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Soybean and rhizobia establish symbiosis in root nodules for symbiotic nitrogen fixation， which effectively relieves its dependence on nitrogen fertilizer in soil. Cytochrome P450 （CYP450）， a heme monooxygenase， is involved in the synthesis and metabolism of many secondary metabolites such as plant signal molecules， plant hormones and flavonoids. In order to explore the function of GmCYP78A71 in nodule formation and nitrogen fixation in soybean， this study analyzed thestructureof GmCYP78A71， and then analyzed its expression pattern and biological function. The results of qRT-PCR and GmCYP78A71 promoter fused GUS staining showed that GmCYP78A71 was specifically expressed in the nodules and the expression abundance increased gradually during nodule development with a peak in mature nodules； the number， fresh weight and nitrogenase activity of nodules of overexpressed transgenic composite plants significantly increased compared with the control， while the number， fresh weight and nitrogenase activity of nodules of RNAi hairy roots significantly decreased. Above results indicated that GmCYP78A71 played an important role in nodule growth and development and nitrogen fixation.

Response Mechanism of Chlorophyll Fluorescence to Low Temperature Stress in Brassica napus L.

Hui YAN

2023, 25(1):  58-64.  DOI: 10.13304/j.nykjdb.2021.0486

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To explore the physiological mechanism of chlorophyll fluorescence response to low temperature stress in Brassica napus L.， the seedlings of rape were treated by low temperature. The chlorophyll fluorescence parameters and their light-response curves under low temperature stress were studied. The results showed that， compared with controls， F_v/F_m and F′_v/F′_m under low temperature stress significantly decreased， and F′_q/F′_m also decreased significantly after stress 5~10 d， while F′_q/F′_v had no significant differences with control after stress 1~3 and 10 d. Therefore， low temperature stress could damage PSⅡ reaction center and reduce the efficiency of capturing excitation energy. At this time， although the proportion of photosynthetic electron transport in the light energy absorbed by reaction center did not significantly change， the conversion efficiency of light energy still decreased significantly after stress 5~10 d. In addition， compared with controls， F'_q/F'_v was stable under low temperature stress. However， after stress 5~10 d， F'_v/F'_m and F'_q/F'_m decreased sharply， and the non-photochemical quenching （NPQ） increased in high light environment. It suggested that the photo-protective mechanism of NPQ rises was drove to dissipate excess excitation energy under long-term low temperature combined with high light condition. Above results provided guidance for obtaining the physiological mechanism of crop response to low temperature stress by analyzing the changes of chlorophyll fluorescence parameters.

Dynamic Changes of Aluminium Ion in the Sepals and Leaves of Hydrangea macrophylla ‘Bailmer’

Zhiyun CHU, Hui QI, Ying LI, Yibing WAN, Zhiyu REN, Chun LIU, Suxia YUAN

2023, 25(1):  65-71.  DOI: 10.13304/j.nykjdb.2021.1110

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Hydrangea macrophylla is an aluminum（Al）-accumulating plant with great ornamental characters. Al ion plays an important role in the sepal bluing， in flower color regulation， as well as in the plant growth and development. Taking ‘Bailmer’ as material，this paper determined the optimum growth temperature and studied the dynamic changes of Al ion in sepals and leaves. The results showed that 23 °C was beneficial for plant growth and uptaking of Al ion in leaves and sepals. The dynamic change trends of Al ion content in the sepals and leaves were similar， which first increased， then decreased， and finally increased. Uptaking rates of Al ion in the sepals and leaves increased rapidly at the early stage， reached to the peak at 12 h， and then decreased rapidly to be stable. The results laid a theoretical foundation for flower color regulation of H. macrophylla.

Response and Evaluation of Leaf Traits and Physiological Parameters of Cyphoma betacea Seedlings Under Shading Environment

Shimin LI, Qiong DONG, Youfan JIN, Shuping LI, Meng LI, Tingbiao LIU, Xingjie ZHAO, Jing CHEN, Ping YE, Meng LYU

2023, 25(1):  72-82.  DOI: 10.13304/j.nykjdb.2021.0508

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To explore the leaf characters and physiological response mechanism of Cyphomandra betacea under different shade environments at the seedling stage， and to determine whether the seedling stage is shady or not and the suitable light environment for its growth， the seedlings of Cyphomandra betacea were taking as experimental materials， and the different degree of shade environments were set including normal light （CK）， light shading （SL）， moderate shading （SM） and heavy shading （SH）. The leaf characters， photosynthetic pigment， non-structural carbohydrates （NSC）， malonaldehyde （MDA）， proline （Pro） and antioxidant enzymes of Cyphomandra betacea seedlings were studied. The shade tolerance index of Cyphomandra betacea was screened by principal component analysis， and the shade tolerance was evaluated comprehensively by a membership function. The results showed that there were significant differences among all indexes of Cyphomandra betacea seedlings under different shading treatments. With the deepening of the shading degree， the parameters such as leaf length， leaf area and the contents of chlorophyll a and carotenoid gradually increased， while chlorophyll a/b， soluble sugar， starch content， and NSC decreased gradually， while the contents of MDA， Pro， soluble protein and the activities of antioxidant enzymes decreased at first and then increased， and the lowest value was found in SM treatment. Eight indexes were screened by principal component analysis including MDA， NSC， chlorophyll a+b， chlorophyll a/b， leaf fresh weight， specific leaf area， Pro content and SOD activity. And the average value of membership function in different treatments was followed as SM>SH>SL>CK. In conclusion， the seedling of Cyphomandra betacea had the characteristic of shade， there was strong light stress under natural light and obvious weak light stress under heavy shade. In a shaded environment， Cyphomandra betacea seedlings could absorb more blue-purple light by increasing single leaf area and contents of chlorophyll and carotenoid， and decreasing chlorophyll a/b to improve light energy utilization efficiency， and the contents of soluble protein and Pro and the activities of antioxidant enzymes increased for alleviating the toxic effect of MDA produced by strong or weak light. To sum up， Cyphomandra betacea seedlings had shady characters， suitable semi-shade environment could be more suitable for the cultivation of Cyphomandra betacea in hot area， under-forest area and garden with the shading intensity 50%， which provided theoretical basis for the cultivation and popularization of Cyphomandra betacea in hot area.

INTELLIGENT AGRICULTURE & AGRICULTURAL MACHINERY

Extraction of Winter Wheat Coverage Based on Improved K-means Algorithm

Wenhao ZHAO, Jiangtao JI, Hao MA, Xin JIN, Xue LI, Haigang MA

2023, 25(1):  83-91.  DOI: 10.13304/j.nykjdb.2021.0941

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In order to rapidly and accurately extract winter wheat coverage at tillering stage before winter， a new method based on the improved K-means Algorithm was proposed. Firstly， the image of winter wheat was transformed to Lab color space. Secondly， the initial clustering center of the K-means Algorithm was obtained by using the Mayfly Algorithm（MA）. At the same time， the Algorithm was improved by using Mahalanobis distance instead of euclidean distance. Finally， the coverage of winter wheat was calculated by using the segmented binary image. The test results of 100 winter wheat images showed that the average segmentation accuracy and the average processing time of the proposed method were 94.66% and 2.03 s， respectively. Compared with excess green （EXG） adaptive threshold segmentation and K-means segmentation based on particle swarm optimization algorithm（PSO-K-means）， the average segmentation accuracy increased by 12.04% and 4.18%， respectively. And the average processing time was reduced by 2.26 and 2.94 s， respectively. The results showed that the segmentation effect of this method was better than the other two segmentation methods， and it could be used to extract the coverage of winter wheat.

Inversion Model of Oleic Acid Content in Rape Seeds Based on Hyperspectral Imaging Technology

Xin LU, Guiping LIAO, Fan LIU

2023, 25(1):  92-99.  DOI: 10.13304/j.nykjdb.2021.1001

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Rape seed with high oleic acid breeding is one of the current breeding directions of rape. In order to find out an efficient and nondestructive method to analyze and determine the oleic acid content， and improve the screening efficiency of rape germplasm resources with high oleic acid， 3 rapeseed varieties were selected as materials in this study， and the spectral imaging information and oleic acid content data of seeds were collected， respectively. The spectral information was preprocessed in 11 ways， and multiplicative scatter correction CMSC was the optimal pretreatment method. 3 quantitative analysis models based on principal component analysis （PCA）， continuous projection （SPA）， competitive adaptive reweighted sampling （CARS） were established， and support vector machine （SVM）， and least square support vector machine （LSSVM） and extreme learning machine （ELM） were established to realize the nondestructive detection of rape oleic acid content. The model was tested by changing the number of training samples， and correlation coefficient （R） and root mean square error （RMSE） were used to evaluate the effect of these methods to validate the stability of the model. The results showed that MSC+CARS+ELM model had the best prediction effect among all the models. The correlation coefficient （Rc） and root mean square error RMSEc of correction set were 0.894 and 1.993 4%， respectively. The Rp and RMSEp of prediction set were 0.868 and 1.069 8%， respectively. It could more accurately predict the oleic acid content and provided theoretical basis for nondestructive testing of rapeseed nutritional quality by hyperspectral technology.

Estimation Models of Phosphorus Contents in Guanxi Honey Pomelo Leaves Based on Hyperspectral Data

Fangliang LI, Qingbo KONG, Qing ZHANG

2023, 25(1):  100-108.  DOI: 10.13304/j.nykjdb.2021.1002

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Phosphorus （P） content in honey pomelo leaves is an important indice for accurate diagnosis and quantitative evaluation of growth status. The hyperspectral estimation models of P contents in honey pomelo leaves were established to provide basis for rapid， non-destructive and accurate estimation of P content. Based on the hyperspectral data and the measured data of P contents in pomelo leaves， the characteristic bands and spectral characteristic variables of the original spectrum and the first-order differential spectrum were extracted， and the single variable estimation model， partial least squares regression model and BP neural network regression model were constructed， and the best estimation model of P content was determined. The reflectance spectra of pomelo leaves with different P contents were significantly different at 350~1 050 nm. The correlation between the original spectrum and the first-order differential spectrum and the leaves P contents in the visible light range were significant， and there were multiple extremums. The sensitive wavelengths of the original spectral curve were 549 and 718 nm， and the sensitive wavelengths of the first order differential curve were 528， 703 and 591 nm， respectively. Among the established regression models， the model with higher coefficient of determination was selected for precision test. The fitting R² （0.775 9） of BP neural network model was the largest， followed by the fitting R² （0.749 9） of partial least squares estimation model. The results showed that the BP neural network model was the best one to estimate the P contents of pomelo leaves， the determination coefficient （R²） of modeling and verification were 0.71 and 0.775 9， respectively； the second was the partial least squares estimation model， the R² of modeling and verification were 0.64 and 0.749 9， respectively. Above results provided a theoretical basis for the nutrition monitoring and diagnosis of large-area honey pomelo leaves and the rational fertilization.

ANIMAL AND PLANT HEALTH

Comparative Analysis of Rhizosphere Soil Microbial Community Structure Between Root-knot Nematode Diseased and Healthy Cucumber

Xuejin YANG, Yuanyuan ZHOU, Xinyi PENG, Jianfeng LIU, Aimin ZHANG, Aiqin JING, Gangyong ZHAO, Dandan CAO

2023, 25(1):  109-118.  DOI: 10.13304/j.nykjdb.2022.0840

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In order to explore the relationship between cucumber root-knot nematode disease and rhizosphere soil microbial community， the microbial community structures between healthy and diseased cucumber root topsoil and rhizosphere soil were analyzed by high-throughput sequencing. The results showed that there was no significant difference in microbial Alpha diversity among 4 soil samples （healthy cucumber root topsoil， healthy cucumber rhizosphere soil， diseased cucumber root topsoil， diseased cucumber rhizosphere soil）， while Beta diversity existed significantly differences among the 4 groups. At the phylum level， the compositions of bacterial and fungal communities were similar among the 4 groups. The relative abundances of Bacteroidetes and Basidiomycota were significantly different among groups， with the highest relative abundance of Bacteroidetes （13.58%） in diseased cucumber root topsoil and Basidiomycota （6.69%） in healthy cucumber root topsoil. At the genus level， the compositions of bacteria and fungi were similar among the groups. The relative abundances of Flavobacterium， Pseudomonas， Streptomyces， Rhizobium， Devosia， Novosphingobium， Ensifer， Cellvibrio and Chitinophaga were significantly different among the groups， which abundances were highest in the diseased cucumber root topsoil with 3.62%， 2.58%， 1.93%， 2.34%， 1.14%， 1.60%， 1.30%， 1.13% and 1.59%， respectively. The relative abundance of Steroidobacter was the highest in healthy cucumber root topsoil with 1.50%. The relative abundance of Pseudallescheria and Chaetomium were the highest in the healthy cucumber rhizosphere soil with 13.73% and 11.00%. Myrothecium had the highest relative abundance in healthy cucumber root topsoil with 7.51%. The relative abundance of Metarhizium was highest in the diseased cucumber rhizosphere soil with 3.99%. The relative abundance of Corynespora was highest in the diseased cucumber root topsoil with 2.64%. Above results should provide some theoretical basis for controlling root-knot nematodes by regulating microbial community structure in plant rhizosphere soil.

Extraction Optimization of Chlorogenic Acid from Tobacco Stalk and Its Antifungal Effect

Yudan ZHANG, Weimin WANG, Bo NI, Xiaohan MA, Junling LI, Zicheng XU, Wei JIA, Jiuchang SHI

2023, 25(1):  119-127.  DOI: 10.13304/j.nykjdb.2021.0888

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In order to expand the utilization approach to tobacco stalk， and explore the antibacterial effect of tobacco stalk chlorogenic acid on tobacco Phytophthora， single factor test and response surface analysis were used to optimize the microwave-assisted extraction process of chlorogenic acid from tobacco stalk and isolated culture was applied to explore the antifungal effect of chlorogenic acid on Phytophthora nicotianae. The single factor and response surface results showed that the optimal extraction process conditions were： solid-liquid ratio （g·mL^-1）1∶15， extraction temperature 50.03 ℃， ethanol volume fraction 50%. Under these conditions， the extraction amount of chlorogenic acid in the crude extract reached 3.48 mg·g^-1. In the vitro experiment， the addition tobacco stalk of chlorogenic acid could inhibit the growth of Phytophthora. 175 mg·L^-1 tobacco stalk chlorogenic acid had a significant inhibitory effect on the colony diameter， which reached to 32% of antifungal rate. In addition， propidium iodie （PI） staining showed that 175 mg·L^-1 tobacco stalk chlorogenic acid could inhibit mycelial growth by destroying the integrity of cell membrane of Phytophthora nicotianae. Therefore， above results provided basis for effective utilization of tobacco straw and development of new natural plant fungicides.

BIO-MANUFACTURING & RESOURCE AND ECOLOGY

Effect of Fulvic Acid on Peat Biomethanation

Ying WANG, Jun LI, Litong MA, Xiaobing CAO

2023, 25(1):  128-133.  DOI: 10.13304/j.nykjdb.2022.0175

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In order to study the effect of fulvic acid on peat biomethanation and produce more methane from peat， different contents of fulvic acid were added into the fermentation system of peat biomethanation， including 0 （CK）， 5 （T5）， 10 （T10）， 50 （T50） and 100 mg·L^-1 （T100）. The total gas production， daily gas production， reducing sugar content， volatile fatty acid （VFA） content and pH were determined during the 43 d fermentation process. The results showed that the total methane production of CK was 16.57 mL·g^-1， and the total gas productions of T5， T10， T50 and T100 treatment groups were 21.23、15.55、15.30、11.45 mL·g^-1， respectively. Among them， the total methane production of T5 treatment group was the highest， which was 1.28 times of CK. On the 8^th and 9^th day， the gas production of different fermentation groups reached the peak， and the T5 group reached the peak gas production of 1.81 mL·g^-1 on the 9 th day， which was 1.70 times that of the CK group. The addition of fulvic acid could promote the degradation of reducing sugar and VFA， and at the same time， the pH of the fermentation system should be suitable for the survival of methanogens. These results showed that the water-soluble fulvic acid in peat’s own component humic acid had a significant promoting effect on peat methane production.

Inversion of Soil Salinity in Farmland of Manas River Basin Based on Combined Model

Xiaohu YANG, Manyu ZHANG, Haichang YANG, Fenghua ZHANG, Yilin JIANG, Xiaolan YI

2023, 25(1):  134-141.  DOI: 10.13304/j.nykjdb.2021.0872

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Salinization is one of the important factors affecting soil quality and crop growth. It is of great significance to use remote sensing technology to obtain soil salinity information on a large scale. This study took farmland in the Manas River Basin in Xinjiang as the research object， and combined the partial least squares regression model （PLSR） and the BP neural network model （BPNN） to construct a combined model to invert the soil salinization status. The results showed that the representative remote sensing indexes with high correlation with soil salinity were normalized differential vegetation index （NDVI）， ratio vegetation index （RVI） and soil-adjusted vegetation index （SAVI）， and their correlation coefficients were -0.746， -0.663 and -0.733， respectively. Among the single prediction models， the partial least squares regression model had the highest prediction accuracy， the coefficient of determination （R²） was 0.759， and the root mean square error （RMSE） was 3.159. The R² combined model was 0.797， and RMSE was 3.611. Its verification accuracy was higher than that of the single prediction model， which was 0.038 higher than that of PLSR model， and 0.094 higher than that of BPNN. Therefore， the combined model could more accurately predict the spatial distribution of soil salinity in the farmland of the Manas River Basin. The soil salinization of farmland in the Manas River Basin was dominated by mild and moderate salinization， accounting for 35.34% and 25.66%， which were consistent with the results of the field survey. Predicting the soil salt content in the study area based on the combined model could obtain a more accurate spatial distribution of soil salt， and provided theoretical basis for the management of farmland soil salinization and the sustainable use of land resources in the Manas River Basin in Xinjiang.

Effects of Different Nitrogen Levels on Physiological Parameters， Yield and Quality of Maize

Weixin DONG, Dongxiao LI, Yuechen ZHANG

2023, 25(1):  142-152.  DOI: 10.13304/j.nykjdb.2021.0630

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Reasonable application of nitrogen can improve nitrogen utilization efficiency， and ultimately affect yield and quality of maize. To study the effect of different nitrogen levels on physiological parameters and yield quality of maize， based on the test materials of ‘Xianyu 335’ and ‘Jingnongke 728’ in this study， 4 nitrogen treatments of N₁（150 kg·hm^-2）， N₂（210 kg·hm^-2）， N₃（270 kg·hm^-2）and N₄（330 kg·hm^-2） were set up to study the effects of different nitrogen levels on growth， physiological parameters， yield and grain quality of maize. The results showed that plant height， leaf area and above ground dry weight of two varieties increased with increasing of nitrogen application， while the stem diameter firsthy increased from N₁ to N₃ and then decreased at N₄ treatment. In addition， leaf area index（LAI） and leaf angle（MTA） similarly showed enlargement with increasing of nitrogen levels， the leaf area index of ‘Jingnongke 728’ was higher than that of ‘Xianyu 335’， and the difference between treatments did not reach the significant level. The chlorophyll contents increased from silking stage to filling stage and decreased at maturing stage， the nitrogen application increased gradually from N₁ to N₃ treatment and decreased at N₄ treatment， soluble protein and soluble sugar contents increased with fertility progression， and ‘Jingnongke 728’ was slightly higher than that of ‘Xianyu 335’. In addition，the contents of soluble protein increased with the increasing of nitrogen application in three stages， while soluble sugar contents increased from N₁ to N₂ treatment and decreased from N₃ to N₄ treatment. Superoxide dismutase （SOD）， peroxidase （POD） activities increased with increasing of nitrogen application， while the malondialdehyde （MDA） content showed opposite trend. The yields of both varieties were the highest under N₂ treatment， but the yield was decreased at nitrogen application more than 210 kg·hm^-2 treatment. Therefore， the N₂（210 kg·hm^-2） treatment was the best nitrogen application treatment. It could be seen that appropriately increasing nitrogen can promote accumulation of dry matter and carbohydrates， and then finally improve yield and quality， which could provide practical reference for nitrogen reduction cultivation in the mountainous plain area of Hebei province.

Response of Rhizosphere Soil Bacterial Community Diversity to Salt Stress in Oat （Avena sativa L.）

Feng LI, Congpei YIN, Ran YIN, Fan WANG, Yongliang HAN, Zhimin YANG, Jiancheng LIU

2023, 25(1):  153-165.  DOI: 10.13304/j.nykjdb.2021.0906

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To investigate the diversity of microbial communities in the rhizosphere of oats （Avena sativa L.） under salt stress， the microbial communities in rhizosphere soils of two oat varieties Souris （S） and Everleaf （E） treated with 0 （Y0）， 3 （Y1）， 6 （Y2） and 9 g?kg^-1 NaCl （Y3） were sequenced using high-throughput sequencing technology. And the relationship between changes in microbial community diversity and salt stress in oats was further analyzed. The results showed that there were significant differences among the bacterial community diversity of different salt stress treatments， and the bacterial community abnudance of S-Y2 and the diversity of S-Y3 samples were highest. At the different classification level， the relative abundances of Proteobacteria， Actinobacteria， Rhizobiales， norank_c_Subgroup_6 and norank_c_Subgroup_6 were higher in the bacterial community. Salt stress affected the community composition of oat rhizosphere microorganisms， and the relative abundances changed significantly with the increase of salt stress. Through 16S functional prediction， COG metabolic pathway database and KEGG metabolic pathway database， it was found that the functions of oat rhizosphere microorganisms were enriched in metabolism， genetic information processing， environmental information processing， cellular processes and organismal systems. These functions of the rhizosphere microbial community were more active under salt stress， which played an important role in growth and stress response of oats. These results provided new space for the isolation of species an strains， and laid a theoretical basis for further mining and utilization of rhizosphere functional microbe.

Effects of Enclosure on Soil Extracellular Enzyme Activities and Nematode Communities in Ulmus pumila Scatered Woodland of Horqin Sandy Land

Xiaolan LI, Ruihui LI, Xuehua LI, Ying GUO, Yifeng TIAN, Shujing JIA

2023, 25(1):  166-174.  DOI: 10.13304/j.nykjdb.2022.0472

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In order to explore the effects of enclosure and grazing on the Ulmus pumila scatered woodland soil system in sandy land， this paper analyzed the different responses of nematode trophic groups， life history groups， metabolic footprints， and the characteristics of extracellular enzymes in different layers （0—20 cm and 20—50 cm） of woodland soil taking soil extracellular enzymes and nematodes as indicators. The results showed that the relative abundance， the abundance of predatory/omnivorous nematodes and cp 2~4 groups in the enclosed sample plot were significantly higher than those in the grazing sample plot. Similarly， the abundance of cp 2~4 groups in 0—20 cm soil layer was higher than that in 20—50 cm soil layer. The result of two-way ANOVA suggested that the treatments， soil layer， and mass partitioning had significant effects on both the metabolic footprint of trophic groups and life history groups （P<0.05）. However， in the same treatment， the metabolic footprint in 0—20 cm soil layer was higher than that of 20—50 cm soil layer. The activities of β-1，4-glucosidase （βG）， β-1，4-xylosidase （βX）， β-1，4-N-acetylglucosaminidase （NAG）， leucine amiopeptidase （LAP） and acid phosphatase （AP） also had significant difference between enclosure treatment and grazing treatment. NAG and AP activities were positively correlated with various metabolic footprints. βG activity had positive correlation with plant parasitic nematode metabolic footprint， predatory/omnivorous nematode metabolic footprint， enrichment metabolic footprint and functional metabolic footprint （P<0.05）. Therefore， short-term enclosure significantly affected the metabolic footprint of soil nematodes and the content of some soil extracellular enzymes in 0—20 cm soil layer. As the metabolic footprint of nematodes was closely related to extracellular enzymes， which indicated that the utilization rate of C， N and P by nematodes changed significantly after enclosure. Above results could provide a basis for the study of the C， N and P cycle in Ulmus pumila scatered woodland soil system in sandy land.

Effects of Different Organic-inorganic Nitrogen Ratios on Soil Carbon and Nitrogen and Upper Leaf Quality in Nanyang Tobacco Area

Geng LI, Yuanyuan ZHAO, Yuyuan CHENG, Jiang WU, Weidong DUAN, Guangting YIN, Qian LI, Chen CHEN, Fei ZHENG, Yuan LIU, Hongzhi SHI

2023, 25(1):  175-186.  DOI: 10.13304/j.nykjdb.2021.0567

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To explore the effect of different organic fertilizer and inorganic fertilizer application ratio on tobacco upper leaf quality and soil carbon and nitrogen structure in Nanyang tobacco area， taking flue-cured tobacco variety Yunyan 87 as the test material， biogas residue and sesame cake fertilizer were used as the organic nitrogen sources， and 6 treatments were set according to different ratios of organic nitrogen to inorganic nitrogen ［T1 （0∶10， purified fertilizer）， T2 （1∶9）， T3 （2∶8）， T4 （3∶7）， T5 （4∶6）， T6 （5∶5）］ to analyzy the corresponding tobacco leaves and soil samples were analyzed. The results showed that compared with T1 treatment， the leaf size， single leaf weight， ratio of potassium to chloride， starch content， output value， and total aroma of the treatments with biogas residue and sesame cake fertilizer significantly increased. Among them， the leaf length， leaf width， potassium ion content， starch content， average price， output value， and total aroma of T4 treatment were increased by 9.23%， 10.49%， 21.79%， 31.91%， 21.31%， 26.57%， and 17.86% compared with T1 treatment， respectively. Compared with T1 treatment， the soil organic carbon content， soil carbon-nitrogen ratio， microbial biomass carbon and nitrogen content were significantly increased in the treatments with organic fertilizer. In Nanyang tobacco area， applying biogas residue and sesame cake fertilizer according to the organic nitrogen∶inorganic nitrogen ratio of 3∶7 could effectively improve the quality， mature tolerance and maturity of upper tobacco leaves， and improve soil carbon-nitrogen ratio.

Screening and Characteristic Study of Angelicasinensis and Notopterygiumincisum Rhizosphere Growth-Promoting Bacteria

Yanli JIN, Xiaojun LAN, Tuo YAO, Xiaoqin DING

2023, 25(1):  187-196.  DOI: 10.13304/j.nykjdb.2021.0534

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In order to obtain plant rhizosphere growth-promoting bacteria （PGPR） for promoting the growth of Angelicasinensis and Notopterygiumincisum， the roots of Angelicasinensis and Notopterygiumincisum were as materials. The strains of fix nitrogen， phosphorus-solubilizing and secreting 3-indoleacetic acid （IAA） were screened and separated by selective medium. And the capacities of fix nitrogen， phosphorus-solubilizing and secreting IAA were determined. The biological taxonomys of screened strains were classified using physiological and biochemical indexes and sequence analysis of 16S rDNA. The results showed that 12 strains with nitrogenase activity were isolated and screened， whose nitrogenase activities ranged from 0.30 to 4.04 nmol C₂H₄·mL^-1·h^-1； 6 strains with inorganic phosphorus-solubilizing were isolated and screened， whose amount of phosphorus-solubilizing was from 290.98 to 420.33 μg·mL^-1；^{and 3 strains with secreting IAA were isolated and screened， whose amount of secreting IAA were from 10.38 to 18.63 μg·mL-1. The results of biological taxonomy indicated that the isolated strains with excellent phosphorus-solubilizing properties belonged to the genus Pseudomonas and Falsirhodobacter，which Pseudomonas was dominant genus. Compared the growth-promoting characteristics of strains， WQP-5 （Pseudomonasgrimontii） isolated from Notopterygiumincisum and MDP-8 （Pseudomonasthivervalensis） isolated from Angelicasinensis with excellent properties were screened， which provided good strains for developing special biological fungus fertilizer for Angelicasinensis and Notopterygiumincisum.}

Effects of Excess Dietary Magnesium on Translucent Egg and Eggshell Microorganism of Xinyang Black Feather

Kui LU, Fuwei LI, Lihui ZHU, Xiaoxiao HE, Lichun WEI, Yonghao ZHU, Huaxiang YAN

2023, 25(1):  197-205.  DOI: 10.13304/j.nykjdb.2021.0546

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To investigate the effects of excessive dietary magnesium on the formation of translucent egg and eggshell microorganism composition of Xinyang black feather laying hens， 48 Xinyang black feather laying hens of 35-week-old whose eggs were prone to egg spotting， were randomly divided into three groups with 16 hens per group （one hen in one cage）. Hens were fed with experimental diets of 843.55 （A）， 2 009.80 （B） and 3 206.05 mg·kg^-1 （C）， respectively. The experiment lasted for 5 weeks. Translucent egg， egg quality and eggshell microorganism were detected. The results showed， compared with B and C treatments， the translucent egg grade of eggs in A treatment significantly decreased （P<0.01）， and the albumen height and Haugh unit significantly increased （P<0.05）. A total of 969 OTUs （operational taxonomic units） were detected by 16s rDNA sequencing， which were 670， 787 and 848 OTUs in A， B and C treatments， respectively. The OTUs increased with the increase of storage time. The OTU number of translucent egg grade 1 was significantly lower than those of other eggs with higher translucent egg grade （P<0.01）. The diets of lower magnesium concentration would reduce translucent egg rate and increase albumen height and Haugh unit.

MARINE AGRICULTURE & FRESHWATER FISHERIES

Comprehensive Analysis of Large-Scale Saccharina japonica Damage in the Principal Farming Area of Rongcheng in Shandong Province from 2021 to 2022

Xiaodong LI, Li SU, Xiaojie LI, Jie LI, Yingjiang XU, Lirong CHANG, Rencheng YU, Dezhou YANG, Shaojun PANG

2023, 25(1):  206-222.  DOI: 10.13304/j.nykjdb.2022.0728

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Large-scale festered Saccharina japonica damage broke out in Rongcheng， one of the principal Saccharina japonica production region in China from November 2021 to April 2022. This natural disaster covered an area of 9 300 hm² and caused a direct economic loss of 20×10⁸ yuan （RMB）. Results of field survey， indoor culture experiments and historical data analyses unveiled the sequential process of this unprecedented event. Driven by surface water current， red tide of Gonyaulax polygramma and Akashiwo sanguinea travelled from the west to the east along and bypassed Shandong peninsula， entering Saccharina japonica farming region. Dissolved phosphorus in seawater was detected to be at 3.68 μg·L^-1， reaching limited level for Saccharina japonica growth. Seedlings of Saccharina japonica grew normally in seawater sampled from the problematic area. Survey buoy mounted at the problematic region recorded a significant low salinity of 30.92 PSU and a much higher surface water transparency during the breaking time. In general， over high seasonal water transparency and exhausted nutrients resulted from the red tides were considered to be the direct causes. Festered blade tissue facilitated propagation of alginate-degrading bacteria， causing secondary damage in the entire farming region.

Distribution of 14 Trace Elements in Argopecten irradians concentricus from Zhanjiang City and Their Dietary Exposure Assessment

Xin FANG, He HUANG, Xuewei ZHOU

2023, 25(1):  223-233.  DOI: 10.13304/j.nykjdb.2022.0475

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In order to clarify the contents and distribution characteristics of 14 trace elements in Argopecten irradians concentricus in different aquaculture areas in Zhanjiang city， and to evaluate the dietary exposure risks， fourteen trace elements in whole soft parts， gonad， mantle， digestive gland， muscle， gill and seawater of farmed shellfish from 6 aquaculture areas were analyzed by inductively coupled plasma mass spectrometry （ICP-MS）. The target hazard quotient （THQ） was used to evaluate potential dietary exposure risks of toxic trace elements. The results indicated that 14 trace elements were detected in all samples， and the content rank was as follows： Mn>Fe>Zn>Sr>As>Cd>V>Cu>Co>Ba>Pb>Cr>Ni>Ga， which also showed regional differences. Trace elements were mainly presented in the gonad， digestive gland and gill. The contents of Cd in aquaculture seawater had the same trends with that in the Argopecten irradians concentricus， and there were seasonal differences among trace elements in shellfish. Significantly positive correlation was observed between As and Cd （P<0.01）. The total target hazard quotient （TTHQ） value of potentially toxic elements was 0.208. Therefore， the distributions of trace elements in Argopecten irradians concentricus were present tissue-specific， in which As and Cd might have the same pollution source， and the accumulation of Cd was affected by the aquaculture environment. There was no dietary exposure risk of toxic trace elements and no health risk induced by the ingestion of Argopecten irradians concentricus， which provided scientific data for the risk assessment of dietary exposure to harmful elements in Argopecten irradians concentricus.