Table of Content

15 August 2018, Volume 20 Issue 8

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Genome-wide Identification and Bio-informatics Analysis of Superoxide Dismutase Gene Family in Setaria italica

ZHAO Yan1, SHENG Yunlong1, SONG Yafei1, ZHANG Jiakuo1, WENG Qiaoyun1, YUAN Jincheng1, ZHAO Zhihai2*, LIU Yinghui1*

2018, 20(8):  1-6.  DOI: 10.13304/j.nykjdb.2017.0493

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Superoxide dismutase (SOD) is a critical antioxidant enzyme existing widely in vivo. Taking millet genome database as search platform, this paper carried out genome-wide scanning on superoxide dismutase (SOD) gene family by bioinformatics method and analyzed its bioinformatics. The results indicated that millet SOD gene family included 8 SOD genes unevenly distributed on 6 chromosomes. The exon numbers of these 8 SOD genes were from 1~9, with protein length of amino acid sequence between 56~334 aa. Among 8 SOD proteins, 5 protiens contained Cu-SOD motif, and 3 proteins contained Mn-SOD motif. Cladogram analysis indicated that millet SOD protein sequence had higher homology with that of rice and Sorghum. The results of this study provided certain reference for further understanding SOD gene family and millet antioxidation mechanism.

Effect of  Irrigating Steady-state Iron Salts on Potato Physiology  and Yield During Tuber Formation Stage

TANG Xinhua, QU Zicheng, ZHANG Xia, ZHANG Hao, WEI Qiaorong, SHI Ying*

2018, 20(8):  7-15.  DOI: 10.13304/j.nykjdb.2018.0124

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In order to study the effect of iron salts on potato physiology and yield and its mechanism of action, this study irrigated different concentrations of steady-state iron salts (10 μmol/L, 100 μmol/L, 1 000 μmol/L) on potted potatoes at tuber formation stage, and then measured SOD activity, MDA content, relative content of chlorophyll, chlorophyll fluorescence kinetics parameters（maximal photochemical efficiency of PSⅡ Fv/Fm）, single plant yield, dry matter weight of per tuber and iron content of tuber dry matter, etc.. The results showed that applying steady-state iron salts could promote plant height growth in potato late growth stage, and increase SOD activity in leaf and relative chlorophyll content. At the initial stage of applying iron salt，the MDA content in leaf was significantly increased and significantly decreased at the later development stage. Fv/Fm was significantly decreased in early applying stage, while it was opposite at the later stage. Applying middle and low concentrations (100 μmol/L, 10 μmol/L) of iron salts were favorable for improving single plant yield. The 100 μmol/L iron salt could significantly increase the single plant yield of Dongnong 310 and Dongnong 311 by 39.6% and 37.3%, respectively. The 10 μmol/L iron salt could significantly increase the single plant yield of Dongnong 312 by 37.8%. 100 μmol/L iron salt could increase the tubers dry matter of single plant by 12.4%~31.9%, While, high concentration of iron salt (1 000 μmol/L) could decrease the tubers dry matter of single plant. Applying different concentrations of iron salts could increase iron content in dry matter of tubers, and the effects of applying medium and high concentrations (100 μmol/L, 1 000 μmol/L) were significant.

Influence of Different Water Supply Negative Pressure on Growth and Main Physiological Indexes of Chinese Cabbage

XIANG Yanyan1, HUANG Yunxiang1*, HUANG Chuyu2, LIU Lishan1, LONG Quan1, LONG Huaiyu3

2018, 20(8):  16-22.  DOI: 10.13304/j.nykjdb.2017.0779

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In order to find out the suitable negative pressure and soil water content for the growth and development of Chinese cabbage under negative pressure irrigation, this paper conducted a pot experiment combining with negative pressure irrigation technology to study the effects of 3 negative pressure levels (-5.0 kPa, -10.0 kPa, -15.0 kPa) on the growth and physiological index of Chinese cabbage in 2 types of vegetable soils (alluvial garden soil and red-garden soil). The results showed that the biomass and root system activity (TTC reduction) of Chinese cabbage was the highest at -5.0 kPa treatment in 2 types of vegetable soils. Along with the decrease of water supply pressure, biomass and root system activity decreased significantly. Proline content was the highest at -10.0 kPa treatment, significantly higher than that of -5.0 kPa and -10.0 kPa treatments. Water use efficiency was the lowest under -5.0 kPa treatment, significantly lower than that of -10.0 kPa and -15.0 kPa treatments. By analyzing the biomass, water use efficiency and physiological responses to soil moisture of Chinese cabbage, the suitable negative pressure was -5.0 kPa in 2 kinds of tested soils, and the moisture content was 25% for the soil derived from alluvial garden soil and 19% for soil derived from red-garden soil.

Effects of Aluminum Stress on Growth and Physiological Characteristics of White Balsam Pear Seedlings#br#

MENG Changjun

2018, 20(8):  23-28.  DOI: 10.13304/j.nykjdb.2018.0191

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In order to explore the physiological mechanism of white balsam pear under aluminum stress, this paper studied the effects of aluminum stress at different concentrations (50 mg/L, 100 mg/L, 250 mg/L, 500 mg/L, 800 mg/L) on the growth and physiological indexes of white balsam pear seedlings. The results showed that 50 mg/L AlCl3 had no significant inhibitory effect on the seedlings of white balsam pear after 20 d stress. With the increase of aluminum stress concentration, the inhibition effect on seedlings of white balsam pear gradually became stronger. Under the stress of 800 mg/L AlCl3, the growth of white balsam pear seedlings were significantly inhibited, and plant height was only 20.16% of the control. Comparing with the physiological indexes, the growth indexes of white balsam pear seedlings (plant height and fresh weight) were more sensitive to aluminum stress. Under aluminum stress, white balsam pear would resist the damage caused by aluminum stress through increasing POD activity. Under aluminum stress, the decrease of chlorophyll content and root activity was important reason for the inhibition of white balsam pear growth.

Establishment of Leaf Occurrence and Growth Simulation Model of Main Tobacco Varieties in Southwest Tobacco Growing Area

SUN Yanguo1, DONG Jianxin1, WU Yuanhua1, WANG Chengdong1, FENG Changchun2, LING Aifen2, MA Xinghua1*

2018, 20(8):  29-38.  DOI: 10.13304/j.nykjdb.2017.0602

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In order to clarify the dynamic process of tobacco leaf development in southwest tobacco growing areas and realize accurate and controlled production of tobacco leaves, this paper carried out field comparative experiments to study the leaf occurrence and growth rhythm of 4 major cultivated varieties including K326, NC89, Yunyan 85 and Honghuadajinyuan, and established Richards growth dynamic models, respectively. The results showed that the R2 values of all growth models were above 0.980, indicating that the models had high degree of accuracy. The leaf occurrence models of these 4 varieties were all of atypical “S” type growth curve, while the leaf growth models were of typical “S” type growth curve. The leaf numbers of different varieties were basically the same, 38~40 pieces. But the leaf occurrence process was obviously different. The leaf number of Honghuadajinyuan  reached the maximum at 35 d after transplanting, and the other 3 cultivars reached the maximum leaf number at 42 d after transplanting. The order of maximum middle leaf areas of different cultivars was Honghuadajinyuan >K326 >Yunyan 85 >NC89, but their growth process was basically the same. The slow growth period was 12~14 d, rapid growth period was 16~17 d, and stable growth period was 30~31 d.

Effect of the Nitrogen Fixation Positive Regulator NifA on the Transcription of the Electron Transport Complex rnf1 Cluster in Pseudomonas stutzeri

HUANG Yi1, LIU Wei2, LU Chao1, LU Wei1, ZHAN Yuhua1, ZHANG Wei1, YAN Yongliang1*

2018, 20(8):  39-45.  DOI: 10.13304/j.nykjdb.2018.0217

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The electron transport complex gene cluster rnf1 was located within the nitrogen fixation island on the Pseudomonas stutzeri A1501 chromosome, and mutation of this cluster led to a sharply decrease of the nitrogenase activity. In this paper, a conserved binding site was identified in the promotor region of the rnf1 cluster. qRT-PCR results further indicated that the expression of rnf1 gene was dramatically down-regulated in the nifA mutant compared to the wild type, suggesting there was a regulatory role of NifA to the expression of rnf1 cluster. The interaction between NifA and the promoter region of rnf1 cluster was verified using bacteria one-hybrid system in vivo. Furthermore, the prokaryotic expression vector of nifA gene was constructed and the NifA protein was purified, and electrophoresis mobility shift assay showed that NifA and rnf1 promoter region could directly interact in vitro as well. Above results proved that NifA might recognize and bind to the promoter of rnf1 cluster specifically thereby regulating its transcription, and provided basis for further studying the regulation net of nitrogen-fixing genes.

Grain Size and Filling Degree Extraction for Rice Panicle Based on X-ray Imaging

HUANG Chenglong1, YANG Wanneng1,2, WU Di1, DUAN Lingfeng1*

2018, 20(8):  46-53.  DOI: 10.13304/j.nykjdb.2017.0614

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Rice panicles can indicate the final rice yield and dry matter accumulation. Rice grain shape and seed plumpness are of great significance for rice genetic breeding and functional genes analysis. However, the traditional measuring method for grain shape needed threshing and peeling steps, which was inaccurate and time-consuming. And seed plumpness was measured mainly by water-deposition or wind-separation method, which could not achieve the quantitative measurement. Therefore, this paper proposed a new measuring method  to obtain the rice grain traits accurately and fast without threshing and peeling. The imaging modalities was based on X-ray to transmis image of rice panicle. Then the X-ray image was also processed to obtain the single grain image by OTSU, watershed, and labelling algorithms. After that, ellipse detection and edge extraction were applied to extract grain length, width and area. Finally 100 rice panicles were tested, and the results showed that the MAPE was 2.14% and 3.45% for grain length and width, respectively. In addition, the K-means and GMM algorithms were adopted in this study to identify the grain area and husk area. The visual distribution of rice grain filling was obtained based on the ratio of the above areas, which was able to distinguish the filled grain from unfilled grain quantitatively. In conclusion, this study provided a new effective method for measuring the complex traits of rice panicle.

Design and Process Parameters Optimization of Water Hyacinth Compressing-Packing Machine

DENG Yuxuan1, REN Yilin1*, YANG Ruibin2, PENG Chunhui1, YUAN Xiaochen1

2018, 20(8):  54-62.  DOI: 10.13304/j.nykjdb.2017.0596

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Water hyacinth has small bulk density and high water content, which is not conducive to resource utilization. This study developed a water hyacinth compression-packing machine based on the principle of hydraulic packing, determined the main structural parameters of compressing device, discharging device, etc. other parts, and completed the hardware construction and software programming of the control system. In order to explore the impact of machine operating parameters on compressive packing process performance, this paper took feeding rate, mincing degree, dwell time as experimental factors and bale density, yield and water content as targets, and determined the optimal combination of technological parameters through single-factor and orthogonal experiments by comprehensive scoring method. The results showed that the excellent water hyacinth compressing-packing process performance was obtained when feeding weight was 7±0.1 kg, mincing degree was 6.75±2.25, dwell time was 10 s, and packing density was 446.6 kg/m3, yield was 238.8 kg/h, water content was 91.27%, and comprehensive score reached 0.941. The above results provided references for designing water hyacinth compressing-packing machine with optimized technological parameters.

Effects of Covering Paddy Field by Crop Straw in Winter on Nutrition Accumulation and Translocation of Rice Plant

TANG Haiming, XIAO Xiaoping, TANG Wenguang, LI Chao, WANG Ke, CHENG Kaikai, GUO Lijun, SUN Geng

2018, 20(8):  63-73.  DOI: 10.13304/j.nykjdb.2017.0566

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In order to clarify the effects of covering paddy fields by different crop straw in winter on the dry matter accumulation and translocation of rice plant nutrients in double-cropping rice region, this paper took different covering crop straw in winter and double-cropping rice pattern as research objectives and studied the effects of different crop straw covering the paddy field in winter on the dry matter accumulation and translocation of nitrogen (N), phosphorous (P) and potassium (K) of early and late rice plants by small plot experimental in paddy field and taking slack winter season and double-cropping rice pattern as the contrast(CK). The other 4 treatments were ryegrass-double cropping rice(Ry-R-R), Chinese milk vetch-double cropping rice(Mv-R-R), rape-double cropping rice(Ra-R-R), potato-double cropping rice(Po-R-R). The results showed that the material contribution rate of stem and leaf with Po-R-R treatment were higher than that of the other treatments at the maturing stage of early rice. Meanwhile, the material translocation rate and the material contribution rate of stem and leaf with Ra-R-R treatment were higher than that of the other treatments at maturing stage of late rice. The N and P accumulation amount in panicle and above-ground part of rice plant with Mv-R-R treatment were higher than that of the CK at maturing stage of early rice (P<0.05). And the K accumulation amount in stem and above-ground part of rice plant with Ry-R-R, Mv-R-R, Ra-R-R, Po-R-R treatments were higher than that of the CK at maturing stage of early rice (P<0.05). Meanwhile, the N and P accumulation amount in leaf, panicle and above-ground part of rice plant with Po-R-R treatment were higher than that of the CK at maturing stage of late rice (P<0.05). And the K accumulation amounts in panicle and above-ground part of rice plant with Mv-R-R treatment were higher than that of the Ry-R-R, Ra-R-R, CK treatments at maturing stage of late rice (P<0.05). Compared with the CK, the amounts of accumulation and translocation of dry matter in different parts of early and late rice plants were increased by covering the paddy field with crop straw in winter. In general, the measure of covering paddy fields by crop straw in winter could promote the accumulation and translocation of nutrients in every part of rice plant. Among the 4 treatments, Mv-R-R treatment was the most favorable.

Influence of Phosphorus Application Dosage on the Yield and Phosphorus Recovery Efficiency of Different Rice Varieties

YAN Jinyao1, LU Junming2, HOU Wenfeng1, LI Xiaokun1*

2018, 20(8):  74-81.  DOI: 10.13304/j.nykjdb.2017.0722

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Field experiments were conducted to study the effects of P (phosphorus) fertilizer application dosage on grain yield, P use efficiency and economic benefits of different rice varieties, so as to provide theoretical basis for rational application of P fertilizer in rice. The results showed that application of P fertilizer could significantly increase the yield of different rice varieties. The yield was increased by 360~1 326 kg/hm2, and increasing rate was 5.9%~20.7%, compared with the treatment without applying P fertilizer. There were differences in response to P fertilizer by different rice varieties. The yield of Huanghuazhan in different P (P0, P37.5, P75, P112.5) application dosages  was the lowest, and compared with Huanghuazhan, yield increasing rates of the varieties with the highest yield were 42.1%, 48.3%, 48.5% and 56.2%, respectively. There was remarkable quadratic correlation and linear plus platform relationship between P application dosage and grain yields of 6 rice varieties. The theoretical maximum yield was 5 858~9 028 kg/hm2, and recommended phosphorus applying dosage was 30~99 kg/hm2. The yield and economic benefits of Luoyou 8 were higher than that of the other varieties, which were 9 023 kg/hm2 and 16 095 yuan/hm2, respectively. When P fertilizer application dosage was 75 kg/hm2, the P use efficiency of Luoyou 8 was the highest, increased by 20.0% comparing Neixiang 2128 with the lowest P fertilizer use efficiency. It could be seen that there were differences in response to P fertilizer among different rice varieties. Under same conditions, the varieties with high yield and high P utilization efficiency should be used preferentially, and rational P fertilizer application should be applied according to the responses of different varieties.

Effect of Exogenous Growth Regulator on Seed Germination of Maize under Salt Stress

SHAN Hao, ZHANG Hu, CUI Aimin, WANG Yunfeng, ZHANG Jiugang*

2018, 20(8):  82-90.  DOI: 10.13304/j.nykjdb.2018.0288

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Salt stress inhibited crop seed germination, and became the major restriction factor for crops production. In order to explore the mitigative effect of exogenous growth regulators on salt stress and relative mechanism, this paper studied the effect of salt stress on germination of maize seed, and discussed mitigative effect and physiology mechanism of exogenous growth regulator \[γ-aminobutyric acid (GABA), gibberellin (GA3), kinetin (KT), salicylic acid (SA)\] on salt stress taking Xianyu 335 as experimental material. The results showed that: ① the maize seed germination rate decreased, but water uptake rate, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased first and then decreased. All the parameters reached the highest value under 70 mmol/L treatment of salt stress. On the contrary, the contents of malondialdehyde (MDA), soluble protein, soluble sugar and Na+ were gradually increased. ② The exogenous growth regulators could effectively mitigate salt stress and significantly improved seed germination rate, defence enzyme activity, increase contents of K+, Ca2+, Mg2+, and decreased the contents of Na+ and MDA. The exogenous growth regulators could improve salt-tolerant ability of maize, especially GA3 and GABA had performed the optimum effect in mitigating salt stress.

Influence of Phosphorus Fertilization on Nutrient Uptake and Phosphorus Use Efficiency of Cotton under Mechanical Harvest Cropping Model

HAN Wei, YE Zupeng, FENG Lin, GU Huimin, HUANG Guoping, WEI Guangdong, QI Xiaochen, CHEN Bolang*

2018, 20(8):  91-99.  DOI: 10.13304/j.nykjdb.2017.0823

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This paper studied the effects of different phosphates fertilizer application rates on nutrient uptake and phosphorus use efficiency of cotton under machine harvest mode (10 cm + 66 cm + 10 cm + 66 cm + 10 cm) in Xinjiang, so as to provide theoretical basis for rational operation of phosphate fertilizer in cotton harvested by machine. Taking ‘Xinluzao 57’ as research object, the paper studied the 5 different P fertilizer (P2O5) treatments (0, 75 kg/hm2, 150 kg/hm2, 300 kg/hm2, 450 kg/hm2) on dry matter accumulation and N, P, K absorption of each growing period, P use efficiency and yield. The results indicated that  moderately increasing P fertilizer was favorable for dry matter accumulation, yield and N, P, K accumulation increase. All these items reached the highest level especially under 75~150 kg/hm2 treatment. The dry matter accumulation, yield and N, P, K accumulation of various organ were 9.85%, 24.2%, 6.24%, 27.1% and 51.6% higher than those of the control, respectively. Under 75 kg/hm2 treatment, the phosphorus use efficiency, agronomic efficiency, and partial productivity were reduced along with the increase of P application rate. All these items were the highest under 75 kg/hm2 treatment as 2.4%, 13.50 kg/hm2 and 67.39 kg/hm2, respectively. Rational P application promoted the yield increase of mechanical harvest cotton, and under 75 kg/hm2 and 150 kg/hm2 treatments, the yield increased 25.05% and 38.53%, respectively, significantly higher than that of the control. Thus, the application of P2O5 for 75~150 kg/hm2 was the optimal under the conditions of this experiment.

Allelopathy of Different Parts of Momordica charantia

YAN Shilong1§, CAI Bo2,3§, TANG Hualing4, YUAN Yang5, AO Su2,3*

2018, 20(8):  100-107.  DOI: 10.13304/j.nykjdb.2017.0384

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In order to clarify the differences existing in allelopathy of root, stem and leaf of bitter gourd (Momordica charantia L.), this paper studied the effects of  bitter gourd extracts of these 3 parts on seed germination and seedling growth of mung beans \[Vigna radiata (L.) Wilczek\] and rice (Oryza sativa L.). The results showed the extracts of 3 parts had no effect on germination rate of mung beans, but inhibited the germination rate of rice. They delayed the average germination time of mung bean and inhibited its germination index; shortened the mean germination time of rice and had “double effects” on its germination index. The extracts of leaf could inhibit the seed vigor of both mung bean and rice. The 2.5 mg/mL (T1) extracts from various parts of bitter gourd had inhibitory effect on the root length of mung bean, 40 mg/mL (T5) extracts from various parts had significant inhibitory effect on root length and stem length of rice seedlings. Leaf extracts had effects on the mung bean fresh weight, 10 mg/mL (T3), 20 mg/mL (T4) and 40 mg/mL (T5) extracts from each part had inhibitory effect on fresh weight of rice seedlings. The root extracts could promote the dry weight of mung bean, and had inhibitory effect on dry weight of rice seedlings. The comprehensive allelopathic effect of each part on mung bean seed germination was all negative; while that bellow 2.5 mg/mL (T1) on the growth of mung bean seedlings was positive. The comprehensive allelopathic effect of each bitter  part with 10 mg/mL (T3), 20 mg/mL (T4) and 40 mg/mL (T5) concentrations were negative on rice seed germination and seedling growth. The allelopathic inhibitions of bitter gourd parts on 2 receptors were stronger than on the root.

Effects of Maifanitum Mineral Fertilizer on Cigar-wrapper Tobacco Leaves Physiological Characteristics and Industrial Availability

WAN Dejian, WU Chuang, LI Xiuni, LI Meng, SHI Xiangdong*

2018, 20(8):  108-118.  DOI: 10.13304/j.nykjdb.2017.0864

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Taking Hainan 2 as material, this paper conducted a field experiment to investigate the effects of maifanitum mineral fertilizer with different dosages on cigar-wrapper tobacco leaf growth, antioxidant enzymatic activities, osmotic adjustment substances content, photosynthetic fluorescence characteristics and quality of cured tobacco leaf. The results showed that compared with conventional fertilizing, increasing application of maifanitum mineral fertilizer could increase root length, root volume and root system activity, and promote flue tobacco growth (P<0.05); could effectively reduce MDA content in leaves, and activities of antioxidase of SOD, POD and CAT, etc.. Under the condition of increasing application of maifanitum mineral fertilizer, the leaf photosynthesis indexes Pn, Gs, Ci, WUE and chlorophyll fluorescence parameters Fv/Fm, ΦPSⅡ, qp  could be significantly higher than that of conventional fertilization treatment, while the Tr, NPQ were significantly lower (P<0.05). At the same time, increasing application of maifanitum mineral fertilizer could effectively improve the pulling force, balance moisture content, reduce the indices of physical properties including thickness of tobacco leaf, leaf weight and stem ratio, etc.; significantly reduce tobacco leaf nitrogen alkali ratio and increase potassium chloride ratio, ash content and sensory evaluation scores. Above results indicated that increasing application of maifanitum mineral fertilizer could also stimulate tobacco plant growth and development, and improve their physiological characteristics and leaf quality after baking. The application dosage of 450 kg/hm2 had the best effect.

Nutrient Characteristics and Correlation Analysis  of Soil Under Prunus divaricata in Xinjiang

SHANG Tiancui, LIU Ling, ZHAO Yu

2018, 20(8):  119-127.  DOI: 10.13304/j.nykjdb.2017.0656

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In order to verify the changing characteristics of soil nutrients at different altitudinal gradients in Xinjiang Prunus divaricata natural reserve, this paper took the soil in Daxigou  valley at Huocheng county as research object, and determined soil nutrient contents at 0~100 cm soil profile from 6 different altitudes, and analyzed the changing law of soil nutrient contents and their correlations. The results showed that the soil nutrient contents presented obvious vertical distribution characteristics in Prunus divaricata and the contents of soil OM, TN, AN, TP, AP, TK and AK at different altitudes decreased gradually with the increase of soil depth. Variation range of  soil nutrient in Prunus divaricata were as the following: soil OM content was 2.73～128.95 g/kg; soil TN, TP, and TK contents were 0.55～5.28 g/kg, 0.46~3.66 g/kg, 1.399~8.786 g/kg, respectively; soil AN, AP, AK contents were 17.45～146.69 g/kg, 6.31～81.13 g/kg, 6.43～69.94 mg/kg, respectively. The contents of different soil nutrients in soil surface were higher, indicating that the soil nutrients were mainly distributed in soil surface. There were obvious correlation between each soil nutrient, and OM was significantly and positively correlated with TN, TP and TK（P<0.01）. AN was also significantly and positively correlated  with AP, AK, OM, TN and TK（P<0.05）. AP was significantly and positively correlated with AK, OM, TN, TP and TK（P<0.05）. AK was significantly and positively correlated with OM, TN, TP and TK（P<0.01）.

Insecticidal and Antibacterial Activity  of Euphorbia esula Linn. Extract

WANG Dongfang, WANG Qingzhong, GAO Minggang

2018, 20(8):  128-133.  DOI: 10.13304/j.nykjdb.2017.0623

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Biological pesticide has broad prospects for development. Euphorbia esula Linn., as a Chinese herbal medicine, has wide distribution and rich resources, and its own toxicity can be used to develope biological pesticides. By heating 75% ethanol to extract the active ingredients in Euphorbia esula Linn., this paper carried out insecticidal antibacterial biological activity test to provide scientific basis for the development of new biological pesticide. The results showed that the extracts had good toxicity to Drosophila melanogaster and Myzus persicae. The LC50 of the extract was 75.51 mg/mL, and the Drosophila mortality was positively correlated with the concentration of the extract. The toxicity of LC50 was 9.35 mg/mL, and the corrected mortality was 85.59% when the concentration of extract was 50 mg/mL. The extracts had certain inhibitory effect on Escherichia coli, Staphylococcus aureus and Bacillus subtilis, which had a stronger inhibitory effect on Bacillus subtilis and the maximum diameter of inhibition zone was 1.53 cm. The extract of 25 mg/mL had obvious inhibitory effect on the colonies of corn leaf spot in potato dextrose agar(PDA）flat plate. The inhibitory rate was 45.28%, and the control effect of potted maize seedlings was 36.63%.

Soil Erosion and Soil Nutrients Response to Erosion Based on 137Cs in Southern Hilly Area

ZHU Xi1, LIN Jie2*

2018, 20(8):  134-141.  DOI: 10.13304/j.nykjdb.2017.0869

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Soil erosion is one of the most serious environmental problems in China, which has brought  huge impact on ecology and human development. Owing to the close correlation between 137Cs redistribution in soil and soil erosion migration, this paper took it as a tracer and studied the soil erosion and accumulation to calculate the soil erosion rate, space distribution, and also the spatial distribution of soil erosion and spatial distribution of soil migration. This paper adopted 137Cs tracer technology to study soil erosion in Tong Mountain area, and further explored the effects of soil erosion on soil nutrients. The background value of 137Cs in the study area was 1 732.48 Bq/m2. With the increase of soil depth, the mass concentration of 137Cs decreased logarithmically. The 137Cs content in the study area ranged from 787.62 Bq/m2 to 2 380.96 Bq/m2. Soil deposit and soil erosion occurred in the study area at the same time. The 137Cs content in forest land was the highest, followed by bamboo grove and tea plantation. The distribution of TN, TP and SOC in different types of land was also different. There was a very significant linear positive correlation between SOC and 137Cs, but there was no significant correlation between 137Cs and TN and TP. Erosion had the most significant effect on soil surface. Compared with the background area, the 137Cs and SOC at soil surface layer (0~5 cm) both in the erosion and deposition areas had obvious losses, reaching 31%, 17% and 45%, 29%, respectively. The results showed that the soil erosion resistance of woodland was stronger than that of tea garden and bamboo forest. In the process of soil erosion, distribution of SOC, TN and TP would be influenced by soil redistribution with different degrees. Influence on SOC was the strongest. The effect of soil erosion at soil surface layer was the most obvious, the upper soil layer was usually the most concentrated place for nutrient. Therefore, soil erosion would cause soil nutrients loss and pollute down stream and rivers. Many agricultural and environmental problems were worthy of attention.

Prediction of Calorific Value of Straw Biochar Based on Industrial Analysis Index

LIU Jing, YANG Fang, NIU Wenjuan, LIU Zhaoxia, NIU Zhiyou*

2018, 20(8):  142-148.  DOI: 10.13304/j.nykjdb.2018.0275

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In order to effectively predict the caloric value of straw biochar, this paper selected 5 kinds of crop stalks including cotton, wheat, corn, rape and rice. After crushing, drying and carbonization treatment, 175 straw biochar samples were obtained. And the ash content, volatile matter, fixed carbon and gross calorific value were measured by standard methods. On the basis of correlation analysis between carbonization technology, industrial components and calorific value, a prediction model of straw biochar calorific value was constructed by regression approach. The results showed that the carbonization temperature had the most obvious influence on the gross calorific value, and holding time and heating rate had little influence on the gross calorific value. Through variance test analysis, the fitting equations of calorific value proposed on the basis of industrial analysis were significant. And the fitting equations of calorific value based on ash content, ash content and volatile matter, volatile matter and fixed carbon, ash content and fixed carbon had achieved good prediction accuracy.

Study on Compound Substrate Cultivation of Freesia hybrida

YAN Zi1,2, WU Yueqin3, SUN Yi1, TANG Dongqin1*

2018, 20(8):  149-154.  DOI: 10.13304/j.nykjdb.2017.0760

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Preparing 11 compound substrates with 6 basic substrates,  this paper studied effect of compound substrates on vegetative and reproduction growth of Freesia hybrida ‘Shangnong Purple Rose’, so as to screen the suitable compound substrate for its cultivation. The results showed that 3 compound substrates “peat + coco peat + inorganic materials” (C7, C8, C9) combinations were good for the vegetative growth of freesia. They could also improve the growth of scapes height and blossoming of floret, and C7 treatment had the highest abloom rate. The compound substrates “peat + coco peat + inorganic materials” were not only suitable for matter accumulation during the process of bulb growth, but also could improve reproduction coefficient, especially C8 treatment had the best effect. Comparing group “garden soil + peat + river sand” with group “garden soil + coco peat + river sand”, the growth and flowering status were quite similar, in which coco peat and peat were in the same proportion. The too large proportion of common soil would inhibit the growth and development of freesia, and could not meet the needs of freesia growth. Taken together, the compound substrate with “peat + coco peat + inorganic materials” was the best for freesia growth and development. It could improve its vegetative growth, blossoming and bulb development. It was also feasible to replace peat with reproductive coco peat for freesia cultivation. This study had a positive significance for guiding production practice in the future.