Table of Content

15 November 2020, Volume 22 Issue 11

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Comparison of Agricultural Science and Technology Innovation System in Europe and America and Enlightenments to China

CHEN Tianjin1, REN Yufeng2, KE Xiaohua1*

2020, 22(11):  1-10.  DOI: 10.13304/j.nykjdb.2020.0569

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The innovation and development of agricultural science and technology has become an important driving force to promote the development of modern agriculture. In recent years, China has stepped into the fast lane of agricultural science and technology innovation and development. This paper compared the agricultural science and technology innovation system in the United States, United Kingdom, Germany and China, in order to explore the path and method to improve Chinas agricultural science and technology innovation system. The results showed that: ① The particularity of agricultural industry determined the particularity of agricultural science and technology innovation system. The main body of agricultural science and technology innovation, agricultural science and technology innovation environment, agricultural science and technology innovation achievements and applications, and international cooperation of agricultural science and technology innovation interacted to form a complete agricultural science and technology innovation system. ② The close integration of "industry, education and research" was a prominent feature of the American agricultural science and technology innovation system. The United Kingdom payed attention to government guidance, information sharing and knowledge service. Germany was the representative of the information ecotype agricultural science and technology innovation system, and payed attention to information guidance and green and sustainable development. ③ Compared with the agricultural science and technology innovation system in Europe and America, there were still some deficiencies in the agricultural science and technology innovation system in China. In the future, the development and construction of the agricultural science and technology innovation system in China could be comprehensively promoted from the aspects of coordination, planning and construction, team and mechanism construction.

Research, Development, and Safety Administration of Genetically Modified Crops in China

WU Shan, PANG Junqin, ZHUANG Junhong, CHEN Limei*

2020, 22(11):  11-16.  DOI: 10.13304/j.nykjdb.2020.0064

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Genetically modified (GM) technology is the core of modern biotechnology, which can break the boundaries between species to achieve targeted transformation of crop traits. It plays an important role and great potential in easing resource constraints, reducing ecological environment pollution, ensuring food safety, saving water, increasing use efficiency, and expanding agricultural functions. This paper  comprehensively reviewed   the general development process of global GM crops industrialization and introduced the current status and safety management framework in China, including the regulatory system and safety assessment system to  provide theoretical guidance for promoting the development of agricultural biotechnology and the industrialization of GM crops in China.


Map-based Cloning of Rice Short Coleoptile Gene SCP1

WANG Fangfang1,2, LI Yuxiang2, LIANG Yuhang2, HUANG Rongfeng2, ZHANG Yuqiong1*, QIN Hua2*

2020, 22(11):  17-25.  DOI: 10.13304/j.nykjdb.2019.0294

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Rice coleoptile plays an important role in the emergence of rice seedlings from soil surface and is regulated by many hormones. To identify the factors involved in coleoptile growth, this paper  a screened  mutants with abnormal coleoptile growth from  mutagenesis. One  mutant, short coleoptile 1 (scp1), showed significant short coleoptile was isolated. Moreover, the expression level of ethylene biosynthesis genes and ethylene production decreased, and  salt and drought tolerance increased  in scp1 mutant  compared with wild type. The field-grown scp1 mutant exhibited dwarf and small-grain phenotypes. Map-based cloning indicated that SCP1 located in 32.01 kb range on chromosome 5, in which there contained 5 genes. Sequencing analysis demonstrated that OsRGA1 (LOC_Os05g26890) had large fragment deletion in coding region, leading to the loss-of-function of OsRGA1. In addition, a reported mutant of OsRGA1, dwarf-1 (d1), showed similar coleoptile and agronomic phenotype with scp1 mutant, indicating that scp1 was an allelic mutant of OsRGA1. These results would deepen the understanding of the function of OsRGA1, and provided materials for investigating the molecular mechanism of ethylene in rice growth and stress tolerance.

Comparative Transcriptome Analysis of Wheat Leaf in Response to Low Nitrogen Stress#br#

ZHANG Wenyun1, ZHANG Jiancheng2, YAO Jingzhen2*

2020, 22(11):  26-34.  DOI: 10.13304/j.nykjdb.2019.0266

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Nitrogen is the necessary element for wheat growth. It is important to identify genes involved in the control of regulatory network of low-nitrogen stress in wheat through transcription analysis, which has great significance for revealing the mechanism of low nitrogen tolerance and promoting wheat breeding. In this study, Illumina HiseqTM 2500 high-throughput sequencing technology was used to sequence the transcriptome of leaves from Jinmai 47 under normal and low nitrogen conditions. Differentially expressed genes (DEG) were screened and low nitrogen response related genes were analyzed by using the GO and KEGG database for annotation in wheat. The results showed that 52 383 726 and 52 192 061 sequences were obtained from the control and the treatment group, respectively. 1 267 DEG were identified, in which 179 were up-regulated and 1 088 were down-regulated. The GO analysis of DEG showed that 44 functional groups of three categories were identified. According to KEGG metabolic pathway, these genes were assigned to 178 signaling pathways, in which amino acid metabolism, carbohydrate metabolism, lipid metabolism, signal transduction and immune system were mostly enriched. Transcription factor analysis showed that the family of WRKY, MYB and NAC displayed the most significant changes in gene expression under low nitrogen conditions.


Effects of Harvest Date on Maize Grain Moisture Content and Grain Mechanical Harvesting Quality

WANG Ronghuan§, XU Tianjun§, ZHAO Jiuran*, WANG Yuandong, XING Jinfeng, LYU Tianfang, LIU Yuee, CAI Wantao, LIU Xiuzhi, LIU Chunge

2020, 22(11):  32-41.  DOI: 10.13304/j.nykjdb.2020.0316

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Grain mechanical harvesting is the developing direction of maize production in China, selecting maize varieties with suitable growth period, high lodging resistance and dehydrating rate, and adopting the corresponding agricultural machinery and cultivation technology is the effective approach for realizing maize grain mechanical harvesting. Field experiments were conducted in the north of Huang-huai summer maize region, Tongzhou District, Beijing, to study the effect of mechanical harvest date on maize grain moisture content and grain mechanical harvesting quality, under 5 grain mechanical harvest date treatments with physiological maturity (PM)(H1), 5 (H2), 10 (H3), 15 (H4), 20 (H5) d after PM. Maize varieties registered by National Crop Variety Approval Committee Jingnongke 728( JNK728), MC812 and MC121 selected by using maize core inbred Jing 2416 which characterized by high density and lodging resistance, early maturity and fast dehydrating rate as the male parent and the two dominant maize varieties Zhengdan 958(ZD958) and Xianyu 335(XY335) were used as the materials. The results showed that: ① Growth period (emergencing to physiological maturity) of JNK728, MC812, MC121, XY335 and ZD958 was 101, 106, 105, 111 and 113 d, respectively. ② Grain moisture content averaged 31.2%, 29.4%, 27.6%, 26.0%, 24.4% under H1, H2, H3, H4, H5 treatments; the grain dehydrating rate after PM differed significantly among varieties with JNK728 [0.039%·(℃·d) ^-1]＞MC812 [0.037%·(℃·d) ^-1]＞MC121 [0.032%·(℃·d) ^-1]＞XY335  [0.031%·(℃·d) ^-1]＞ZD958 [0.026%·(℃·d) ^-1]. ③ Grain broken rate averaged 7.4%, 6.8%, 6.2%, 5.4%, 5.0%, impurity rate averaged 1.2%, 1.0%, 0.8%, 0.6%, 0.6%, and loss rate averaged 3.7%, 3.4%, 3.3%, 3.3%, 3.1% under H1, H2, H3, H4, H5 treatments; mechanical harvesting quality indexes of grain broken rate, impurity rate and loss rated of JNK728, MC812 and MC121 at H4 treatment could reach GB standard, but ZD958 and XY335 were not suitable for grain mechanical harvesting because of higher grain broken rate. ④ Correlation analysis showed that, maize grain moisture content was significantly correlated with grain broken rate, impurity rate and loss rate, grain loss rate was significantly correlated with grain broken rate and impurity rate. Thus, mechanical harvesting date was the major factor influencing maize grain moisture content and mechanical harvesting quality. Selecting maize varieties with earlier maturity, higher dehydrating rate and lower grain moisture content at harvest, and harvesting at suitable period was the key for realizing maize grain mechanical harvesting in the north of Huang-huai summer maize region. JNK728, MC121 and MC812 which characterized by earlier maturity and higher dehydrating rate after PM were suitable for grain mechanical harvesting at 15 d after PM under the sowing condition of June 15th in the north of Huang-huai summer maize region, ZD958 and XY335 which characterized by relatively later maturity and lower dehydrating rate after PM could not realize grain mechanical harvesting in this region.

Drought Resistance Identification and Comprehensive Drought Resistance Index Screening of Rapeseed（Brassica juncea L.）in North Shanxi#br#

WANG Ruixia, LI Xiaoyu, TIAN Hongxian*

2020, 22(11):  42-51.  DOI: 10.13304/j.nykjdb.2020.0423

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To systematically evaluate drought resistance of rapeseed （Brassica juncea L.）and select reasonable drought resistance indexes, taking 12 mustard rapes as material and using field drought stress assay method, this paper analyzed the effects of drought stress on the photosynthetic physiological parameters and agronomic traits during flowering stage, and combined with subordinate function analysis and principal component analysis for comprehensive evaluation. The results showed that: Jinyou 14, Shenchi rape, Niuwei shao and Jinyou 13 were drought-resist varieties. Principal component analysis was used to synthesize 12 single indicators of drought stress into 4 independent comprehensive indicators. Photosynthetic parameters (37.33%), yield factors (21.31%), transpiration rate (17.42%) and 1 000-seed weight (11.10%) were closely related to drought resistance of rapeseed. The results could provide reference for the selection and cultivation of drought resistant spring rapeseed in northern Shanxi Province.


Codon Usage Profiling of Chloroplast Genome in Magnoliaceae

JI Kaikai1, SONG Xiqiang1, CHEN Chunguo2, LI Ge2, XIE Shangqian1*

2020, 22(11):  52-62.  DOI: 10.13304/j.nykjdb.2019.0937

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Magnoliaceae is primitive angiosperm with important economic, medicinal and ornamental values. Codon is the core element of translation in central dogma, and its characterics analysis of coding region is important to study the gene function and phylogeneitc evolution. At present, 29 chloroplast genomes of Magnoliaceae have been successfully assembled and annotated. Therefore, this paper collected the chloroplast genomes of Magnoliaceae and systematically analyzed the codon usage profiling of chloroplast genomesand decoded the phylogenetic relationship among the 29 Magnoliaceae plants. The results illustrated that synonymous codons and optimal codons in 29 chloroplast genomes from Magnoliaceae had the same codon usage preference and ending with A/U. The natural selection was the main factor in codon preference. Furthermore, the phylogenetic trees from 29 Magnoliaceae chloroplasts was constructed by using whole genome sequences, CDS sequences and codon preference RSCU values, respectively. It was found that the phylogenetic relationship from codon usage preference was significantly different with others, while the phylogenetic trees from chloroplast whole genomes and CDS sequences were closer to the true relationship among 29 Magnoliaceae plants. Those results further supported that the base mutation and non-coding sequences played an important role in the evolution process of organisms.

Research Progress of miRNA Regulating Residual Feed Intake of Livestock and Poultry

BAI Hao1, YANG Baolong2, DONG Zhaoqi2, LI Xiaofan2, JIANG Yong2, CHANG Guobin1,2, CHEN Guohong1,2*

2020, 22(11):  63-68.  DOI: 10.13304/j.nykjdb.2020.0643

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Residual feed intake (RFI) is an important evaluation index for feed efficiency of livestock and poultry. miRNAs are a class of endogenous non-coding single-strand RNA molecules with  length of around 22 nt, which are important regulators for gene expression. Previous studies revealed that miRNAs were closely related to feed intake and energy metabolism of animals, which participated in the regulation of RFI in cattle, pigs, chickens and other animals. This article summarized the research status of RFI, especially the research progress of miRNA regulating RFI of livestock and poultry in recent years, which would help to reveal the molecular regulation mechanism of RFI trait, provide new ideas for the improvement of feed efficiency and efficient production of livestock and poultry, and provide a theoretical basis for molecular breeding of the high-quality livestock and poultry.

Heterologous Expression and Characterization of Alkaline Protease From Cordyceps fumosorosea and Beauveria bassiana

REN Yaxin1,2, LUO huiyin1, YAO Bin1, WANG Guozeng2*, TU Tao1*

2020, 22(11):  69-78.  DOI: 10.13304/j.nykjdb.2019.0174

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Alkaline protease is a widely used protease preparation and plays a crucial role in many fields. Therefore, it is important to discover high-quality alkaline protease genes and overexpression successfully for the needs of industrial applications. In this study, the alkaline protease genes, pa1 and pa2 from Cordyceps fumosorosea and Beauveria bassiana, respectively, were ligated to the expression vector pPIC9, and successfully expressed in Pichia pastoris GS115 with high yield. The purified recombinant alkaline protease PA1 and PA2 both showed optimum activities at pH 8.5 and 60 ℃, which distinguished from other enzyme counterparts. The two enzymes showed good thermostability at 50 ℃, and both retained about 70% of activity after incubating for 10 min at 60 ℃. PA1 and PA2 had wide pH ranges and retained more than 80% of activity after incubation for 1 h from pH 4.0 to 11.0. In addition, PA1 and PA2 also exhibited some resistance to surfactants and reducing agents. All these favorable enzymatic properties made PA1 and PA2 attractive for potential applications in industrial.

Load Analysis of Rotary Cutter Shaft for Power Tiller Based on DEM and MBD Theory

LIU Yu, LIU Yuping, ZHANG Tuo

2020, 22(11):  79-86.  DOI: 10.13304/j.nykjdb.2019.0314

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Rotary tillage components are the core components of the power tiller, and their quality directly affects the tillage efficiency and work quality of the tiller. The typical rotary cutter shaft and purple soil in Chongqing were taken as the research objects. Based on the discrete element method (DEM) and multi-body dynamics (MBD) theory, the nonlinear visco-elastic plastic contact model (edinburgh elasto-plastic adhesion model, EEPA) was used to analyze the knife roller farming process on the EDEM and Recurdyn software platform under the condition of the forward speed 0.2 m·s^-1, the rotary speed 110 r·min^-1 and the tilling depth 150 or 200 mm. At the same time, the equivalent torque of the cutter shaft was tested on the soil-bin test bed in laboratory developed by our team. The results showed that the torque variation rules of different tool holders on the same cutter shaft were similar, but the values were not consistent. The equivalent torque of the cutter shaft was not simply equal to the torque of a single tool holder timed the number of tool holders. Furthermore, the variation law of the equivalent torque of the cutter shaft was same under different tillage conditions, and the maximum relative error between the simulation results and the experiment results with the tilling depth of 150 and 200 mm were 14.01% and 11.49%, respectively. The  results provided the reference for discussion between rotary blades and soil, as well as optimization of the tilling performance of the tiller.


Study on the Operation Ways and Parameters of Cold Aerosol Sprayer at Different Growth Stages of Tomato in Greenhouse

LI Chuanyou1, DOU Shuo2, XIONG Bo1, ZHANG Li1, LI Zhen1, TENG Fei1, LIU Jingrui1, YANG Ye1, CHEN Yumei1

2020, 22(11):  87-94. 

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In order to optimize the operation ways and parameters of cold aerosol sprayer in the greenhouse, this paper sprayed the tomato canopy at different growth stages by two operation ways of inter-row and corridor, and the indexes such as droplet deposition distribution, pesticide deposition, pesticide ground loss and pesticide utilization rate were measured. The results showed that: in terms of droplet deposition distribution, pesticide deposition, pesticide ground loss and pesticide utilization rate and other indexes, the inter-row operation was better than the corridor operation at different growth stages of tomato, and the leaf front was better than the leaf back. When the pest control in the greenhouse required a large amount of spray and a high droplet coverage rate, inter-row operations should be carried out; when the preventive operation of crops in the greenhouse or pesticide spraying had good internal absorption and did not require a high droplet coverage rate, the corridor operation can be carried out, and the nozzle angle could be adjusted within ±15° to ensure the uniform distribution of droplet deposition in front, middle and back of the canopy. This study could provide reference for the plant protection operation of the facility scaffolding type vegetable.

Extraction of Grape Greenhouses From GF-2 Remote Sensing Images#br#

TANG Zixia, LI Mengmeng*, WANG Xiaoqin, QIU Pengxun

2020, 22(11):  95-105.  DOI: 10.13304/j.nykjdb.2019.0759

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With the development of facility agriculture, it is important to extract updated and accurate information regarding agricultural greenhouses for fine-tuning the growth mode of agricultural economy and efficiently using agricultural resources. This paper applied an object-based image classification random forest to extract grape greenhouses from a GF-2 remote sensing image in southern hilly areas acquired in May 2017. For the classification, 15 optimal features of image objects were selected based on the scale evaluation tool (ESP) and the Ratio of Mean Diff. to Neighbors (ABS) combining with Standard Deviation (RMAS) methods. The results showed that: ① combining ESP and RMAS methods provided a promising means to select the optimal segmentation scale parameter for image segmentation. ② Feature selection based on random forest  reduced data redundancy and was crucial to improve extraction accuracy. Among the 15 selected optimal features, spectral features had the highest importance, followed by texture features and geometric features. ③ By using the selected optimal features, this method produced the grape greenhouses classification with an overall accuracy of 92.5%, F-value of 0.91, and global error index (GTC) of 0.12. The proposed method was of high potential for grape greenhouses extraction in the southern hilly region, and provided an effective means for extracting agricultural greenhouses in many other areas.


Correlation Between Larval Development and Gall Growth of Pontania dolichura

QI Jingyu1,2§, XUE Qiqi1,2§, LIU Chunyu1, ZHANG Qian1, YAN Xiaolu1, MEN Lina1,2*, ZHANG Zhiwei1,2*

2020, 22(11):  106-115.  DOI: 10.13304/j.nykjdb.2020.0240

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Pontania dolichura is a leaf-eating pest that harms and seriously affects the landscape greening effect of Salix babylonica. In order to study the correlation between the size of gall and the morphology of larva in different developmental stages, and to understand the occurrence and development law and the mechanism of gall formation, the gall length, gall width, gall thickness, gall wall thickness and larva body length, body width, head length and head width of P. dolichura of 55 groups in different investigation stages were systematically measured. Principal component analysis and detrended correspondence analysis (DCA) were carried out on the measured morphological characteristics data, and linear regression analysis was carried out among the morphological indexes of gall, larval morphological indexes and between gall and larval morphological indexes. The results showed that the larval development of P. dolichura showed obvious gradient changes, and there were significant linear relationships (P<0.000 1) between the morphological indexes of gall, as well as the morphological indexes of larva. However, the linear relationship between gall thickness and larval body length was a conditional function, that is, when the larval body length is less than or equal to 6.90 mm, there was a significant linear relationship, and the linear equation was y=1.771x + 0.653 (R2=0.920，P<0.000 1). Therefore, in practice, according to the linear relationship between the larval morphology and its gall, the growth and development status of the larva in the gall could be judged by easy-to-measure indexes such as the length, width, thickness and wall thickness of the gall, and the growth and development law of the larva could be determined, thus providing a scientific evaluation standard for the growth and development of the larva and a theoretical basis for its scientific control.

Inhibition of Volatile Organic Compounds Produced by Bacillus subtilis Czk1 on Red Root of Rubber Tree

LIANG Yanqiong, LI Rui, WU Weihuai, XI Jingen, TAN Shibei, ZHENG Jinlong, HUANG Xing, LU Ying, HE Chunping*, YI Kexian*

2020, 22(11):  116-123.  DOI: 10.13304/j.nykjdb.2020.0378

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Red root is one of the most devastating diseases of rubber tree caused by Ganoderma pseudoferreum. In order to provide new materials for the prevention and control of red root disease of rubber trees, the inhibitory effect of volatile organic compounds produced by Bacillus subtilis Czk1 on Ganoderma pseudoferreum was investigated. In this study, G. pseudoferreum was used as the target fungus, and the antifungal activity of 12 kinds of pure volatile organic compounds  produced by Czk1 was detected by pair culturing method. Virulence of the active volatile organic compounds was determined by the growth rate method. The effect of volatile organic compounds on morphology and cell membrane permeability of G. Pseudoferreum cells were detected. The results showed that the 12 volatile organic compounds had different degrees of antifungal activity against G. pseudoferreum, and their inhibition rate ranged from 15.2% to 100%. Among them, benzaldehyde had the strongest antifungal activity against pathogens, and the rate reached 100%. In the determination of the virulence of 9 pure compounds to pathogens, the EC₅₀ of benzaldehyde, 3,5-dimethoxyacetophenone, and butylated hydroxytoluene were  20.30, 30.62, 40.96 μg·mL^-1, respectively. The concentration of the three mixed components was 25 μg·mL^-1, the inhibitory rate against G. pseudoferreum was 670%. The mycelia of pathogen were greatly twined, the cell wall became thinner, part of the membrane structure was incomplete and the permeability of pathogen cell was affected after  treated with volatile organic compounds. The good fungistatic activity of volatile organic compounds produced by Czk1 was the result of the synergy of these volatile organic compounds. These volatile organic compounds had great application prospects and could be used as chemical pesticide substitutes to prevent and cure rubber tree root disease.

Influence of Sowing Date on Yield and Quality of Knojac (Amorphophallus virosus) Intercropping in Rubber Plantation#br#

YUAN Shuna, PAN Jian, HUANG Jianxiong, ZHENG Dinghua, GUI Qing, WANG Jun, ZHOU Lijun*

2020, 22(11):  124-132.  DOI: 10.13304/j.nykjdb.2020.0192

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In order to determine the suitable sowing date of konjac (Amorphophallus virosus) intercropping in rubber garden, two types of rubber-konjac intercropping systems, whole production cycle intercropping rubber plantation (WPCIRP) and conventional rubber plantation (CRP) were established in present study. Three sowing dates, February 25th (SD1), March 25th (SD2) and April 25th (SD3) in 2016 were set up, and the effects of sowing date on growth period, leaf characteristics, tuber yield, and contents of soluble sugar, protein and starch of konjac tuber were investigated. The results showed that there was no significant difference among sowing date treatments in growth period of konjac under WPCIRP, but the growth period under CRP was shortened with the delay of sowing date, and there was significant difference between SD1 and SD3 treatments. Leaf numbers and petiole base diameter of konjac intercropping in WPCIRP increased significantly with the delay of sowing date, but the petiole length was not significantly affected by sowing date. There was no significant difference in leaf number of konjac under WPCIRP among different sowing date treatments. The petiole length and base diameter of konjac decreased significantly with the delay of sowing date. The average yield of konjac intercropped under WPCIRP was the highest at SD1 sowing date, which was 22.76 t·hm^-2, but there was no significant difference among three sowing date treatments. The yield of intercropping konjac in CRP increased gradually with the delay of sowing date, the yield of SD3 was the highest and significantly higher than that of SD1. Sowing date had no significant effect on the contents of soluble sugar, soluble protein and starch of konjac tuber. To sum up, the intercropping of konjac under WPCIRP was suitable for sowing from February 25th to April 25th, and proper early sowing was beneficial to its yield formation. It was better to intercrop konjac from March 25th to April 25th under CRP, and proper late sowing was beneficial to its yield formation. The yield of konjac in WPCIRP was significantly higher than that in CRP. The present research provided theoretical basis for high-yield and high-efficiency cultivation of konjac intercropping in rubber plantation.

Effect of Forest and Grass Restoration and Traditional Farming on Soil Aggregates and Organic Carbon Content in Rocky Desertification Area

WANG Jin, LIU Ziqi*, ZHANG Guo, LI Yuan, BAO Enyu

2020, 22(11):  133-143.  DOI: 10.13304/j.nykjdb.2019.0593

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In order to find out the particle size distribution, structural stability and organic carbon distribution characteristics of soil aggregates after restoration of forest and grass vegetation in rocky desertification control area, this paper compared four species of forest and grass vegetation (honeysuckle, pitaya, pepper and grassland) in Guanling-Zhenfeng Huajiang rocky desertification control demonstration area with traditional planting corn field. The wet screening separate method was used and the agglomerate was measured to compare and analyze the stability of soil aggregates and the distribution of organic carbon in aggregates under the control of rocky desertification and traditional farming modes. The results showed that:① The water-stable aggregates of the five plots were mainly composed of large aggregates (>0.25 mm), and the content of large aggregates (>0.25 mm) showed grassland > honeysuckle ground > pitaya ground > corn field > pepper field, the aggregate content decreased with the decrease of the particle size. ② The mean weight diameter(MWD) and geometric mean diameter (GMD) of the aggregates were grassland > honeysuckle ground > pitaya ground > corn field> pepper field. ③ The organic carbon content of soil aggregates was: honeysuckle ground > grassland > pitaya ground > pepper field >corn field, indicating that the soil organic carbon content was improved after changing from traditional planting mode to forest grass vegetation. Except for the pepper field, the stability of soil aggregates and the soil organic carbon content in other plots were higher than that in the corn field. In conclusion, in the rocky desertification control area, returning farmland to forest and vegetation restoration was favor to improve soil structure and increase carbon storage capacity, and promote the improvement of karst rocky desertification ecological environment.

Influence of Defoliant on Defoliation Effect and Fiber Quality of Cotton under Two Kinds of Mechanical Harvesting Modes

ZHOU Xianlin1, QIN Qin1, WANG Long1,2, LI Lu1, HU Chengcheng1, HONG Xiuchun1, WANG Wei1, ZHU Haiyong1,2*

2020, 22(11):  144-152.  DOI: 10.13304/j.nykjdb.2019.0628

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In order to screen suitable cotton defoliants and mechanical harvesting modes in Changji cotton area, by taking Zhongmian M02 as the test material and using randomized block design, this paper carried out the experiment with two different mechanical harvesting modes: M1(10 cm + 66 cm + 10 cm + 66 cm + 10 cm + 66 cm), M2 (76 cm + 76 cm + 76 cm), and five defoliants: T1(detolone+ethephon), T2(ruijiao+ethephon), T3(ruituolong+ethephon), T4(kuoxiao+ethephon), T5(saideli+ethephon), and studied the influence of different defoliants on defoliation effect and fiber quality of cotton under two different mechanical harvesting modes. The result showed that: different defoliant treatments significantly increased the defoliation rate and boll opening rate, meanwhile different defoliants displayed the same defoliation effect on cotton under two different mechanical harvesting modes. Different defoliant did not show significant effect on cotton yield under the same mechanical harvesting mode, and small effect on yield components such as single boll weight, lint percentage and fiber quality. Compared with M1 machine mining mode, the defoliation rate, boll opening rate and average boll number increased significantly under M2 mechanical harvesting mode, but the yield significantly reduced. These results showed that although the single boll weight and boll number per plant of tested variety had a certain increase under M2 mechanical harvesting mode, it did not compensate for the effect of density reduction on the yield, which might be related to cotton varieties and the use technology of defoliants. Therefore, although it contributed to improve the quality of machine-harvested cotton, the application of M2 mechanical harvesting mode should fully consider the synergistic effect among varieties, density and yield. Overall considerations, T1, T2 and T3 were more suitable for popularization and application in Changji cotton area.

Effects of Temporal Variation of Soil Moisture on the Growth and Water Use Efficiency of Maize

WANG Zhuan, ZHU Guolong, LONG Huaiyu*, ZHANG Renlian, SHEN Zhe, QU Xiaolin, YU Kefan

2020, 22(11):  153-164.  DOI: 10.13304/j.nykjdb.2019.0648

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To explore the effects of temporal variation of soil moisture on the growth and water use efficiency(WUE) of maize, the pot experiment was performed by using negative pressure irrigation (-5, -10, -15 kPa) and artificial irrigation (AI) to generate relatively stable or fluctuating soil moisture respectively. The effects of different treatments on soil moisture content and total water consumption, agronomic characters, photosynthesis, dry matter quality and water use efficiency were analyzed. The results showed that: ①the average soil moisture content of -5, -10, -15 kPa and AI was 53% FC (field capacity), 47% FC, 38% FC and 78% FC, respectively, from maize jointing stage to maturity. NPI treatment was stable soil moisture content with weak temporal variation, and AI was the fluctuating soil moisture content with medium temporal variation. ②Compared to 78% FC with medium temporal variation, higher plant height, thicker stem and larger leaf area were observed under 53% FC and 47% FC with weak temporal variation, implying the soil moisture was more conducive to the growth and development of maize. The SPAD value and net photosynthetic rate of the 53% FC with weak temporal variation were higher, and the photosynthesis of the maize was more favorable. ③Compared to 78% FC with medium temporal variation, the dry matter quality, dry weight, biomass water use efficiency (WUEB) and yield water use efficiency (WUEY) of maize under 53% FC with weak temporal variation significantly increased by 39.0%, 106.6%, 28.8% and 87.3%, respectively. ④ The agronomic characters, photosynthesis, water use efficiency and other indexes of maize increased with the increase of water content in the range of 38% FC to 53% FC under stable weak temporal variation. In conclusion, when the average soil moisture content was 47% FC to 78% FC, the soil moisture condition with weak temporal variation was more favorable to the growth and development of maize and the improvement of the water use efficiency. Under the condition of the same temporal variation, the growth and water use efficiency of maize in the range of 38% FC to 53% FC increased with the increase of the water content.

Impact of Rice-fish-chicken Ridge Cultivation on Rice Population Growth and Yield

LIANG Yugang1, LI Jingyi1, WANG Dan2, YU Zhengjun1, HUANG Huang1*, CHEN Can1*

2020, 22(11):  165-175.  DOI: 10.13304/j.nykjdb.2020.0370

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In order to explore the influence of the combination of rice ridge cultivation and rice-fish-chicken cultivation model on the population growth characteristics and yield formation of rice, based on the previous studies on ridge cultivation, rice-fish cultivation and rice-chicken cultivation, the combination technology of raising chickens and raising fish in rice ridge cultivation was put forward. A field experiment with 4 treatments, including conventional rice ridge cultivation (CK), rice-fish ridge cultivation (RF), rice-chicken ridge cultivation (RC), and rice-fish-chicken ridge cultivation (RFC), were carried out to study the growth and yield of rice under different cultivation treatments. The results showed that, the average yields of rice treated in RFC and RC treatments were both similar with CK treatment in two tested years. Although there were differences in average effective panicle, total grains per panicle, seed setting rate and 1 000-grain weight, there were no significant differences between different treatments. The yield, effective spikes number, total grains per spike, seed setting rate and 1 000-grain weight of rice in RF treatment all decreased significantly by 29.98%, 19.70%, 4.84%, 3.99% and 5.74%, respectively. In two tested years, the average dry matter accumulation of stems, leaves and spikes in RFC and RC treatments had no significant difference with CK, but increased significantly compared with RF. Dry matter accumulation of rice stems and leaves in RFC, RC and CK treatments was significantly higher than that in RF treatment before full heading, with an average increase of 56.23%, 50.66% and 54.15%, respectively; the decrease of dry matter accumulation after full heading was slower than that in RF treatment, and the leaf area index was maintained at a high level, with an average increase of 41.38%, 38.35% and 38.23%. In two tested years, RFC, RC and CK treatments had higher population growth rate, net assimilation rate and photosynthetic potential than RF treatment, in which the population growth rate increased by 77.94%, 70.29% and 76.69%, net assimilation rate was 40.07%, 39.47% and 38.87%, and photosynthetic potential was 38.39%, 35.49% and 36.69%, respectively. To sum up, rice-fish-chicken ridge cultivation and rice-chicken ridge cultivation could help rice accumulate more dry matter and improve leaf area index, population growth rate, net assimilation rate and photosynthetic potential, thus ensuring the stable rice yield.

Effects of Nutrient Management Measures on Soil Fertility of Pitaya in Dry-hot Valley

WANG Zhongyun1, YU Yanghua2*, WANG Qianzi1

2020, 22(11):  176-186.  DOI: 10.13304/j.nykjdb.2019.0346

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To explore the characteristics of soil fertility quality in different nutrient management methods of pitaya land and reveal the change law of soil fertility quality,  4 treatments were conducted including farmyard manure (FM), alfalfa (AF), bio-organic fertilize(BOF), and litter coverage(LC), which were used to analyze the change of soil fertility indexes and identify the impact of soil fertility quality in different nutrient management methods. The results showed that with various nutrient management methods, the soil fertility was significantly different. The pH  was below 7 in LC, indicating weakly acidic, while it displayed weakly alkaline in other nutrient management. LC treatment showed better effects on increasing the contents of soil organic C, available P, available Mn and available Fe, while AF management did not showed benefit effects on soil organic C, total N and total K.The content of soil organic C and the majority of available elements displayed a lower level by  FM management as well as BOF management. The pH  had major impacts on soil available elements. In addition, there was a significantly positive correlation between soil macroelements and soil microelements. Using different nutrient management methods, the comprehensive soil fertility quality indexes were sorted as follows: LC（1.793）>AF（0.949）>FM（-0.995）>BOF（-1.747）. LC was a more suitable management method for soil nutrient accumulation, followed by AF and FM. BOF had the lowest effect on soil nutrient accumulation, but it had a good effect on improving crop yield.