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Table of Content

    15 April 2019, Volume 21 Issue 4
    Industrial Poverty Alleviation Mode Supported by Research Team of Pomology Discipline —— Based on the Cases by Citrus Team of Huazhong Agricultural University
    LAN Hanqi1, DENG Xiuxin 2*
    2019, 21(4):  1-7.  DOI: 10.13304/j.nykjdb.2018.0684
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    Industry development is the fundamental strategy for poverty alleviation and revitalization of rural areas. As an important pillar industry of agricultural efficiency and farmers income increase, the fruit industry has the comparative advantages of industrial poverty alleviation, including not competing for land with grain and cotton, developing natural endowment, highlighting precision guidance and benefiting the ecological environment. This paper summarized the practical experience of poverty alleviation in the fruit industry including staying committed to the unity of short-term and long-term benefit, seed and talent cultivation, technological and economic feasibility, special products and strong technical support, scientific research and its application in production. Finally, this paper distilled the basic paradigm of poverty alleviation mode supported by research team of pomology discipline and suggested that a systematic thinking be carried on; fruit growing technology system, government-university-farmer-market social system and pomology subject support system be planned as a whole.
    Research on Measurement of Cooperation Effect Between China and CGIAR
    HUANG Dandan, ZHANG Xuefu*
    2019, 21(4):  8-15.  DOI: 10.13304/j.nykjdb.2018.0696
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    Since China joined CGIAR, it has established long-term friendly partnership and cooperation with CGIAR. China also gained a lot of benefits during the cooperation with CGIAR, but there was quantitative evaluations missing in measuring Chinas CGIARs cooperation, so it was necessary to build an effect index system, methods as well as the giving weight to each index. This paper took 13 CGIAR centers as examples, and formed the performance scale of research achievements of each center based on the evaluation index system and performance basic data of the cooperation effect between China and CGIAR. The research performance of each center was calculated based on the weight, and the research performance and potential of each center was comprehensively evaluated through the comparison of horizontal (between each center) and vertical (in different years), which had a reference for China to allocate its contribution to various CGIAR centers.
    Cloning and Functional Analysis of a Potato Glycosyltransferase-Like Gene StKOB1
    BAI Yiping1, LIU Jing1,2, LEI Zhaoxia1, TANG Wei1,2, WANG Hongyang1,2*
    2019, 21(4):  16-24.  DOI: 10.13304/j.nykjdb.2018.0550
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    Glycosyltransferases play important roles in plants stress responses by glycosylating hormones and secondary metabolites. In order to unravel the effect of glycosyltransferase in potato resistance aginst Phytophthora infestans, a glycosyltransferase-like gene StKOB1 was cloned from potato cultivar ‘C88’, and its expression and function were analyzed. Using quantitative reverse transcriptase PCR, the expression pattern of StKOB1 in response to Phytophthora infestans, methyl jasmonic acid (MeJA), salicylic acid (SA), ethephon (ET) were analyzed. Transient expression of StKOB1 and virus-induced gene silencing (VIGS) of NbKOB1 were performed in N. benthamiana to investigate KOB1 function against P. infestans. The results indicated that StKOB1 protein contained one transmembrane domain (27~47 aa) and one glycosyltransferase function domain (115~381 aa). The expression of StKOB1 was induced by P. infestans and MeJA. Transient expression of StKOB1 didnt enhance disease resistance of N. benthamiana, while NbKOB1-silenced plants increased susceptibility to P. infestans. The results suggested that the StKOB1 was involved in potato defense to P. infestans.
    Study on the Seed Germination and Seedling Growth Characteristics of Different Genotype Rapeseed Varieties
    WANG Rui, ZHENG Weidong, LIU Duanmei, LIANG Li
    2019, 21(4):  25-34.  DOI: 10.13304/j.nykjdb.2018.0265
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    In order to discuss the seed germination characteristics of different genotype rapeseed varieties in the Yangtze River basin, this paper selected 23 rapeseed varieties with different genotypes from the planting areas in the middle and upper reaches of the Yangtze River and carried out seed germination and seedling emergence test in a light incubator to analyze the correlation and membership functions of 14 parameters describing seed germination and seedling characteristics. The results showed that: Among all these 23 different genotypes, the seedling vigor index, root length, seedling stem dry and fresh weights of Zhongshuang 11 and Youyan 10 were the highest, which ranked at the front through membership function analysis. The stem dry weight and 1 000-grains weight were the lightest of Jinhuanghou and Ronghuayou 6, which ranked at the bottom. The 7 varieties with an average degree of membership over 0.52 were Zhongshuang 11, Zhongyou 589, Liangyou 9, Youyan 10, Youyan 50, Zhiyuanyou 8 and Qinyou 6. These cultivars had relatively high parameters, such as seedling vigor index, root length, dry and weight of seedling stem, 1 000-grains weight, etc.. These research results provided theoretical basis and practical references for selecting varieties for simplified & direct seed planting of rapeseed in the Yangtze River basin.
    Transgenic Tobacco Expressing GNA and ACA gene Confers the Resistance to Myzus persicae
    YANG Caifeng, LI Gangqiang, WANG Nan, LIU Dehu*
    2019, 21(4):  35-41.  DOI: 10.13304/j.nykjdb.2019.0020
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    Aphid is a common crop pest. As a kind of agricultural pest and the carrier of plant viruses, aphid results in serious damage in the development of agriculture and its control has always been a difficult problem faced by many scientists. A bivalent plant expression vector PB1121-GA containing the agglutinin genes of Glanthus nivalis and Amaranthus caudatus was constructed and transformed into tobacco by using Agrobacterium-mediated disc method. 65 KanR transgenic tobacco plants were regenerated. Then 5 transgenic tobacco plants expressing different levels of agglutinin were selected from these KanR plants through genomic PCR, ELISA, RT-PCR and Western-blot. A preliminary aphid bioassay experiment was carried out for investigation of the transgenic tobacco resistance to Myzus persicae, which showed that the aphid inhibition rate was significant, with the maximum reaching to 85.8%. Above results provided a theoretical basis for the research on breeding of crops resistant to aphid and the application of bivalent aphid resistance genes.
    Research Progress on Aflatoxin Detoxification
    WANG Jingying1, WANG Zhuo2, YAN Peisheng1*
    2019, 21(4):  42-51.  DOI: 10.13304/j.nykjdb.2018.0335
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    Aflatoxin is natural toxin produced by fungi. It can be mainly classified as aflatoxin B, aflatoxin G, and aflatoxin M. To mankind and livestock, aflatoxins have high toxicity, teratogenicity, mutagenicity, and carcinogenicity. Compared to other aflatoxins, aflatoxin B1 is the most toxic. Aflatoxin B1 and aflatoxin M1 have been classified as Group 1 (established carcinogens to human) by International Agency for Research on Cancer. Therefore, how to detoxify aflatoxins has won increasing attention at home and abroad. This paper mainly expounded the physical methods, chemical methods, and biological methods for aflatoxin detoxification at home and abroad, laying emphasis on reviewing the varieties of biological methods for aflatoxin detoxification, detoxification mechanisms, and toxicity of degradation products. Before ending, the paper also prospected the future for research activities in this field.
    Rice Canopy Image Segmentation Using Support Vector Machine and Otsus Method
    HUANG Qiaoyi1,2, ZHANG Mu1, LI Ping1, FU Hongting1, HUANG Xu1,TANG Shuanhu1*
    2019, 21(4):  52-60.  DOI: 10.13304/j.nykjdb.2018.0160
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    In order to resolve the difficult problem of rice canopy image segmentation caused by variable light intensities in the fields, this paper discussed a rice canopy image segmentation algorithm based on support vector machine (SVM) and maximum variance between classes (OTSU). Firstly, 2 class training images (rice S1 and background S2) were captured from the rice canopy images under different illumination conditions, and the density of R, G, B, r, g, b, L*, a*, b*, H, S, and V color indices from RGB, rgb(standard RGB), CIE L*a*b* and HSV color spaces for rice (S1) and background (S2) training images were analyzed. The g, a*, b*, and S color indices, whose histogram distributions of S1 and S2 were significant bimodal, were selected as key color indices. Afterwards, an optimal hyperplane Z(Z=0.421g+0.753a*+0.152b*+0.051S+0.085) in multi\|dimensional color spaces including g, a*, b*, and S color indices were obtained by support vector machine. Finally, the Z(x, y) of any rice canopy image was calculated, and threshold Zt value was calculated by OTSU method. The accuracy and robustness of the proposed method was examined over 90 test images under different illumination conditions (overcast days, cloudy days and sunny days), and compared with the performances of ExG & OTSU. The accuracy of segmentation and light intensity robustness of this method were analyzed. The results showed that the accuracy of ExG & OTSU method was influenced significantly by light intensity, and decreased along with the light intensity increasing. The robustness of light intensity was poor. The segmented error of the proposed method for the images, taken on overcast days, cloudy days, and sunny days were 7.30%, 8.72%, and 8.98%, respectively. The accuracy of segmentation was higher and with better robustness of light intensity. Therefore, the proposed method had higher segmentation accuracy and robustness of light intensity, and could provide technical reference for accurate segmentation of rice canopy image in fields under changeable illumination.
    Design and Experiment of Clamping Mechanism About End-effector for Citrus Harvesting Robot
    WANG Yi, ZHANG Mao, LIU Bo, LIU Sa, HE Yu, XU Hongbin*
    2019, 21(4):  61-69.  DOI: 10.13304/j.nykjdb.2018.0266
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    It is an important means to improve the harvesting ability of the harvesting robot by improving harvesting success rate of end-effector. The simply supported beam shear method can cut the carpopodium more easily than the cantilever beam shear mode with same cutting speed and diameter, and the simply supported beam shear mode can be achieved by clamping the citrus. Therefore, the harvesting success rate of the harvesting robot could be increased by adding a clamping mechanism to the end-effector. Through ultimate squeeze test of citrus, the ultimate load that citrus could stand was 14.0 N under the condition of pressure surface diameter of 14.12 mm. Based on the results and citrus parameters, the fingers of clamping mechanism were designed, and the maximum ultimate clamping force for citrus was determined under 102.41 N. According to the previous research results and force analysis of the carpopodium, the minimum clamping force of clamping mechanism was determined more than 3.79 N. The control system design was completed by the movement characteristics of clamping mechanism, the 3-dimensional model of clamping mechanism was established and finite element analysis and verification were performed. The prototype of the clamping mechanism was made and gripping experiments for different citrus varieties were carried out. The clamping mechanism was installed on the end-effector, the picking comparative experiment between the non-clamping mechanism and with clamping mechanism were performed under natural conditions. The experimental results showed that the clamping mechanism could achieve the non-destructive clamping of various citrus varieties. The harvesting success rate of end-effector was increased from 70% to 85% after adding the clamping mechanism. The harvesting success rate of end-effector was significantly improved, thereby improving the harvesting operation ability of harvesting robot.
    Design and Experimental Verification of A Woodland Cleaning Device for Eucalyptus Plantations
    XU Mingxian, WANG Lihai*, SHI Xiaolong, LIU Tienan, ZHANG Guanghui, MENG Qingkai
    2019, 21(4):  70-78.  DOI: 10.13304/j.nykjdb.2018.0655
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    In order to protect the commercial forest resources and forest ecological environment in the north, people expanded the cutting of southern Eucalyptus plantation. For better harvesting the plantation, it is necessary to clean up the forestland before harvesting. So this paper designed and studied a new type of clearing device for forestland. The woodland cleaning device was mainly composed of cutter shaft, cutter head, cutter, etc.. The working head structure of forest clearing device was determined through analyzing the measurement data of tree spacing, weed and shrub species, shrub diameter and shrub density in the study area. Using the measured data, this paper analyzed and determined the key parameters: dimension parameters of the tool shaft, cutter head and cutter, speed of tool shaft and power consumption; and built SolidWorks model of forest land cleaning device. By transient analysis function of ANSYS, this paper simulated and analyzed the cutting tool, and made clear that the instantaneous stress and strain of cutting tool in cutting shrubs were well. ANSYS and Adams were used to analyze the model and dynamic balance of tool shaft, proving that the design of speed and size of tool shaft was reasonable. The results of analyzing cutter deformation indicated that cutter design was reasonable and within the prescribed range. Finally, the dynamic balance test of the cutter shaft and shrub cutting experiment on the prototype were all carried out. The results showed that the maximum effective vibration speed of cutter shaft was 0.13 mm/s and the maximum noise was 87.7 dB. The prototype could successfully cut within 16 shrubs, meeting all relevant standards and design requirements. The simulation and experimental results proved that the key parameters were correct and designed clearing device could complete the scheduled clearing work.
    Research Progress on System Structure and Key Technology of Agricultural Internet of Things
    YUE Yujun1, YUE Xuefeng2, ZHONG Yunyun1
    2019, 21(4):  79-87.  DOI: 10.13304/j.nykjdb.2018.0313
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    At present, the application of Internet of things (IOT) in the field of agriculture is on the rise. As a new driving force for transformation and upgrading of traditional agriculture to modern agriculture, IOT is a necessary condition for agricultural information and intelligence. Taking the system structure of agricultural IOT as thread, this paper systematically reviewed the research status of agricultural IOT. Firstly, starting from the development of agricultural IOT, this paper summarized and extracted its system structure, and discussed 4 key technologies in detail, respectively. Then, the paper introduced the application status of agricultural IOT in 4 representative fields. Finally, by analyzing the existing problems of agricultural IOT, the future research focus and development trend were forecasted.
    Effects of Different Control Measures on Tomato Quality, Yield and Disease Incidence in Greenhouse
    SHI Jianhua1§, QI Lianfen1§, WANG Dandan1, LI Yan1, ZHANG Qingyin1, GE Xizhen2, TIAN Dongliang1*
    2019, 21(4):  88-95.  DOI: 10.13304/j.nykjdb.2018.0432
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    Taking tomato "Ruifen 1" as experimental material, this paper studied the effect of different control measures on tomato fruit quantity, quality and disease incidence in greenhouse, so as to identify the best prevention and control measure for high quality and high yield of tomato in greenhouse. The paper set up 4 treatments, including the control (W1), chemical pest prevention and P-chlorophenoxyacetic acid pollination (W2), biological pest prevention and P-chlorophenoxyacetic acid pollination (W3), biological pest prevention and bumblebee pollination (W4). The main components analysis method was used to evaluate the twelve indexes, including single fruit weight, vitamin C content, titrate acid content, soluble sugar content, soluble solid content, sugar acid ratio, solid acid rate, taste acceptance, physiological disease fruit incidence rate, late blight incidence rate, gray mold incidence rate, and leaf mold incidence rate. The results showed that the 12 indicators of the tested tomato were converted into 2 principal components, representing 88.57% genetic information of the main quality traits. Comprehensive score ranking was W4>W3>W2>W1. Treatment W4 (bumblebee pollination under biological prevention measure) had the highest comprehensive score. The plants under W4 treatment had good field conditions and low disease incidence rate. Therefore, through biological control measures combined with bumblebee pollination can improve tomato yield and quality, reduce disease occurrence. These results provided technological guidance for tomato cultivation.
    Pathogenicity Study of Chryseobacterium oncorhynchi B8 Isolated from Sturgeon (Acipenser baerii) in North China
    HE Suxu1§, MA Guoqing2§, NIU Wenjing1, LI Youshen1, ZHOU Zhigang1*
    2019, 21(4):  96-103.  DOI: 10.13304/j.nykjdb.2018.0282
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    This paper screened the pathogen from the focus of Acipenser baerii, and combined with drug susceptibility test, infection path and analysis of host related indicators to understand the pathogenicity of the pathogen. In this study, by artificial regression infection test, a virulent strain B8 was isolated from the sick sturgeon, which had stronger pathogenicity to sturgeon, tilapia and zebrafish. This virulent strain B8 was identified as Chryseobacterium oncorhynchi by 16S rDNA gene sequence analysis. In addition, strain B8 had resistance to 10 routine antibiotics, and was highly sensitive to erythromycin and neomycin. The infection path showed B8 was firstly colonized in mucosal tissues (intestine and gills) then lymphoid tissues (liver, spleen and kidney). In all detected tissues, the highest numbers were obtained at 48 hpi, then gradually decreased. Moreover, significant up-regulation of IL-1β was found in intestine of sturgeon (peak value at 24 hpi), then gradually dropped down. Significant differences were appeared between 12~48 hpi compared to the unchallenged group (P<0.05). Furthermore, the antimicrobial response (lysozyme and ROS) showed notable up-regulation in the kindey of challenged sturgeon (peak value at 48 hpi). There were significant differences at 24~48 hpi compared to the unchallenged group (P<0.05). The results reported for the first time bath challenge virulent strain C. oncorhynchi B8 studies on its pathogenicity provided reference for prevention and treatment of diseases caused by Chryseobacterium of Acipenser baerii.
    Effects of Packaging Materials on Storage Quality of Citrus unshiu
    SUN Guoliao, CHEN Hong*, LI Shanjun, ZHANG Yanlin, XIONG Junqiang, SHAO Xian, XIA Binyun
    2019, 21(4):  104-113.  DOI: 10.13304/j.nykjdb.2018.0438
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    In order to determine the suitable film materials for the storage of Citrus unshiu, and prevent the cross infection of citrus fruit during storage period, reduce the decay rate and maintain the good sensory quality of citrus unshiu, this article used the commercial maturity of Citrus unshiu as experimental material to study the effects of three commonly used packaging materials, including polyethylene (PE), polyvinyl chloride (PVC), and oriented polypropylene (OPP), on the quality during their storage period. The changes of comprehensive sensory evaluation, weight loss rate, sugar-acid ratio, vitamin C content, CO2 content, total bacteria colonies, texture profile analysis (TPA) and the other indicators of Citrus unshiu were measured regularly during storage period. The original indicators were integrited into 6 principal component factors by using principal component analysis. The cumulative contribution rate was 91.186%. A comprehensive evaluation model was used to calculate the comprehensive evaluation index F value. The results showed that different film packaging materials had different preservation levels for Citrus unshiu during storage. The F value was sorted as PE>OPP>PVC. PE was better than OPP and PVC in keeping the sensory qualities of Citrus unshiu and suppressing water loss and keeping a high ratio of sugar to acid and lower concentration of carbon dioxide. Above results provided the application basis and theoretical reference for the study of storage and preservation of Citrus unshiu and Citrus packaging machinery in the future.
    Influences of Various Voltage by Different Obtaining Methods on Sample Temperature in Radio Frequency Thawing During Computer Simulation
    LI Yulin1,2, LI Feng1,2, WANG Yifen1,2,3, JIAO Yang1,2,4,5*
    2019, 21(4):  114-122.  DOI: 10.13304/j.nykjdb.2018.0142
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    Because experiment could not obtain voltage between 2 electrode plates needed for radio RF thawing finite element in simulation, this paper used COMSOL Multiphysics software to study 3 different voltages (fixed voltage, experimental anode voltage, and theoretically derived voltage) for simulating RF defrosting frozen beef samples in 3 sizes (Little: 160 mm×102 mm×60 mm;Middle:220 mm×140 mm×60 mm;Large:285 mm×190 mm×60 mm), and then compared the effectiveness of the voltage selection for heating rate and temperature distribution between the simulated and actual results. The results showed that the experimental anode voltage and fixed voltage were close to each other in the range of 7.2~8 kV. But the theoretically derived voltage was the highest among all, about 9.2~10.7 kV. The simulated result was mostly close to the experimental results, when selecting 70%~80% of the theoretically deducted value as the input voltage for computer simulation. This research conclusion could provide reference for obtaining input parameter of accurate simulate RF thawing process.
    Review on Research and Application of Food Safety Traceability System
    HE Dehua, SHI Zhongxin
    2019, 21(4):  123-132.  DOI: 10.13304/j.nykjdb.2018.0326
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    Food quality and safety is a hot issue attracting much attention at present. Traceability system can help consumers, governments and food suppliers obtain enough commodity information in market transactions, so as to improve the low efficiency of information transmission in the market and situation of “adverse selection” of consumers; and alleviate consumers concerns and distrust on enterprises and governments when problems occurred in food safety. This paper summarized the definitions and record forms of traceability system, and behavior of consumers, suppliers and governments, and also the design methods of traceability system, etc.. Through comparative analysis of existing deficiencies at home and abroad, this paper pointed out the research direction of food quality safety traceability system in China in the future, hoping to provide some new perspectives for the follow-up research.
    Effects of Different Land Use Types on Soil Aggregate Composition in Rocky Mountain Area of Northern Huai River
    LIN Jie1, ZHANG Yang1, ZHU Yanfang1, DONG Bo1, PAN Ying1, DING Mingming2
    2019, 21(4):  133-142.  DOI: 10.13304/j.nykjdb.2018.0207
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    In order to explore the effect of developing economic forest on soil properties, this paper took the small watershed in northwestern Ganyu district as the research area, selected 3 typical economic forest types(chestnut forest, apple forest and hawthorn forest, which were all converted from conifer-broad leaf forest), took conifer-broad leaf forest with no human interference as the contrast, and studied the status and change law of soil aggregates under different land use types by the wet sieving method and explored the impact mechanism based on non-multidimensional scaling(NMDS). The results showed that:①With the increase of grain size in 0~10 cm and 10~20 cm soil layers, the percentage content of aggregates in different land use types increased first and then decreased. On the whole, the difference of aggregate composition in different land use types was mainly manifested as the difference between conifer-broad leaf forest and economic forest. The grain sizes with different percentage content of aggregates were mainly < 0.25 mm and > 1 mm. ② The mean weight diameter (MWD) was significantly different under different land use types, 0~10 cm, the soil MWD value of conifer-broad leaf forest was significantly greater than that of chestnut forest; 10~20 cm, the soil MWD value of chestnut forest and hawthorn forest was significantly greater than that of apple forest; 20~30 cm, the soil MWD value of hawthorn forest was significantly greater than that of apple forest, and the geometric mean diameter (GMD) did not change significantly. ③NMDS axis analysis showed that soil bulk density was significantly related to NMDS1, soil total organic carbon, total nitrogen and carbon-nitrogen ratio were slightly related to NMDS1 and soil total organic carbon was slightly related to NMDS2. The study indicated that the construction of economic forest affected the status of soil aggregates, which was mainly manifested by the decrease of large aggregate ratio and increase of micro-aggregate ratio in the soil. In general, the stability of economic forest aggregates was lower than that of conifer-broad leaf forest. The stability of apple forest soil aggregates was the worst. Soil bulk density and soil carbon and nitrogen were the important factors affecting the composition of soil aggregates.
    Influences of Humic Acid on Physiological Characteristics and Yield of Quinoa Under Different Phosphorus Levels
    PANG Chunhua1,2, HUA Yanhong1, ZHANG Yongqing1, HE Xiao1, XUE Rong2
    2019, 21(4):  143-150.  DOI: 10.13304/j.nykjdb.2018.0486
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    The optimum amount of fertilizer applied to improve the growth and yield of quinoa was explored by applying humic acid at different levels of phosphorus application, which provided the theoretical basis for high-quality cultivation of quinoa. This paper took “Quinoa 1” as experiment material in pot and studied the effects of humic acid on roots physiological indexes and yields of quinoa under different phosphorus levels including control (0 g/kg), low phosphorus (0.1 g/kg), medium phosphorus (0.2 g/kg) and high phosphorus (0.3 g/kg). The results showed that the chlorophyll content, the antioxidant enzyme activity and the yield of quinoa under different phosphorus levels increased first and then decreased with the increasing of phosphorus application, all of which were the best at medium phosphorus level. Applying of humic acid at different phosphorus levels could increase chlorophyll content, root activity, SOD enzyme activity, POD enzyme activity and yield of quinoa. Grain yield and growth rate were higher when applying humic acid under low phosphorus and applying humic acid under medium phosphorus than those under control group, among which grain yield was increased by 88.42% and 100.76% respectively. However, the best agronomic utilization rate and partial productivity of phosphorus fertilizer was attributed after apply humic acid under low phosphorus level. In sum, applying humic acid under low phosphorus level was the most suitable for quinoa growth and could increase its yield and utilization ratio of phosphate fertilizer.
    Adaptability Evaluation of Different Kidney Bean Varieties (Lines) in Northern Shanxi
    YIN Lili1, XING Baolong2*
    2019, 21(4):  151-157.  DOI: 10.13304/j.nykjdb.2018.0606
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    To investigate the adaptability of different kidney bean varieties (lines) in Northern Shanxi, this paper investigated the growth period, agronomic characters, economic characters and yield of 12 collected kidney bean varieties (lines) in Northern Shanxi, and evaluated their adaptability by principal component analysis. The results showed that kidney bean BY2015-1 could not mature in Northern Shanxi; however the other 11 varieties (lines) had better adaptability in Northern Shanxi. 9 characters of 11 kidney bean varieties (lines) were analyzed using principal component analysis. 3 principal component factors including production and plant type factor, growth period and pod length factor, and branch number factor were obtained. The total cumulative contribution rate reached to 86.054%. According to the principal component scores and composite score, 4 kidney bean varieties (lines) including Zhongyun 5, Long 12-2614, Zhongyun 4 and Zhongyun 6 were suitable for cultivation in Northern Shanxi. Variety Zhongyun 5 was the highest comprehensive scoring, and its yield was the highest. Cluster analysis showed that 11 varieties (lines) of kidney beans could be divided into two categories. Zhongyun 5, Long 12-2614, Zhongyun 4 and Zhongyun 6 were grouped together.This study provided new ideas and references for the evaluation and screening of kidney bean varieties (lines).
    C, N, P Stoichiometric Characteristics Analysis of Litter and Soil in Evergreen Broad-leaf Forest in Longxi-Hongkou Reserve of Sichuan Province
    XU Anni1, WANG Chen1, CHEN Runshao1, LIU Yang1, ZENG Jian1,2*
    2019, 21(4):  158-167.  DOI: 10.13304/j.nykjdb.2018.0205
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    Taking the evergreen broad-leaf forest in Longxi-Hongkou reserve of Sichuan province as object, this paper explored the effect of evergreen broad-leaf forest soil and characteristics of ecological stoichiometry of total organic carbon, nitrogen and phosphorus in soil and litter in response to altitude, soil layer and forest type. The results indicated that: ① The contents of C, N and P in soil and litter showed rising trend along with elevation increasing. All these contents were significantly and positively correlated with elevation. ② The soil depth was significantly and negatively correlated with N/P and C/P in soil. The elevation and forest type were significantly and negatively correlated with C/P of litter, while only forest type was significantly and negatively correlated with N/P of litter. ③ The C/N ratios of soil and litter were higher than that of forest ecosystem in China, indicating the litter decomposition rate was slow, degree of mineralization and humification was lower, risk of soil nitrate leaching was lower, and nutrient storage capacity was better. Soil N & P contents were significantly and negtively correlated with C/N and C/P of litter indicated that litter decomposition in this area was restricted both by nitrogen and phosphorus elements in soil. These research findings may provide scientific basis for studying soil nutrient supply and its limiting factors in Longxi-Hongkou forest and evaluating soil quality and forest managing ability there.