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Table of Content

    16 October 2019, Volume 52 Issue 20
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Molecular Basis of Kernel Development and Kernel Number in Maize (Zea mays L.)
    Ran ZHAO,ManJun CAI,YanFang DU,ZuXin ZHANG
    Scientia Agricultura Sinica. 2019, 52(20):  3495-3506.  doi:10.3864/j.issn.0578-1752.2019.20.001
    Abstract ( 732 )   HTML ( 95 )   PDF (984KB) ( 672 )   Save
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    Grain yield per ear of maize (Zea mays L.) is composed of both kernel number and grain weight. The number of kernels on an ear is determined by not only the number of kernel rows which is closely related to the inflorescence development, but also the number of fertile florets generated by the flower meristem. Therefore, those genes for inflorescence architecture and flower development are potentially involved in the genetic control of kernel number. Maize kernel is a single-seeded fruit comprised of the maternally derived pericarp, and embryo and endosperm derived from double fertilization. Both embryo and endosperm account for the vast majority of the mature kernel mass, and directly determine the kernel size and weight. In this paper, we outlined the genetic controls of kernel number with the emphasis on the inflorescence and floret related genes that are involved in the CLAVATA- WUSCHEL (CLV-WUS) feedback loop, hormone biosynthesis and signaling, floral organ development and sex determination. In particular, we described the regulatory network models for interplays among phytohormones including auxin, gibberellin, cytokinin and strigolactone in the inflorescence architecture and floral organ development. We also summarized those embryo and endosperm developmental genes involving in processing and editing of mitochondrial transcripts, transcription and translation of some chloroplast DNAs as well as nuclear RNAs. Most of these genes encode PPR proteins targeted to mitochondria or plastids. Recently, several studies have identified a new pathway to control kernel development by regulating the transcription and processing of pre-mRNA within the nucleus. Here, we also discussed the association between these genes and kernel number or kernel weight, and the potential areas of research for deciphering molecular mechanisms of grain yield in maize.

    Functional Characterization of a UDP: Flavonoid Glycosyltransferase Gene UGT73C19 in Glycine max
    ShaoKang DI,QingGang YIN,YaYing XIA,YongZhen PANG
    Scientia Agricultura Sinica. 2019, 52(20):  3507-3519.  doi:10.3864/j.issn.0578-1752.2019.20.002
    Abstract ( 904 )   HTML ( 84 )   PDF (1274KB) ( 494 )   Save
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    【Background】 Flavonoids are a group of important plant secondary metabolites accumulate in soybean, which are involved in many physiological activities, including soybean growth, development and stress resistance. Glycosylation catalyzed by UDP-glycosyltransferase is a key step in flavonoid biosynthesis. 【Objective】 The objective of the present study is to investigate the in vitro enzymatic activity and in vivo function of a soybean glycosyltransferase protein encoded by the UGT73C19 gene, the achievement of which will deep our understanding on the mechanism of the flavonoid biosynthesis in soybean. This study will provide gene resource and theoretical basis for the genetic modification in soybean. 【Method】 Flavonoids in the leaves of soybean core germplasm resources were detected by HPLC, and the expression level of UGT genes were detected by qRT-PCR. The coding region of the UGT73C19 gene was cloned from cDNA of soybean leaf (Williams 82). The amino acid sequences of UGT73C19 were searched in the NCBI database, and the software MEGA5 and DNAMAN were used for multiple sequence alignment and the construction of a phylogenetic tree. The recombinant UGT73C19 protein was expressed in E. coli and its enzymatic activity was determined towards various flavonoid aglycones. All the enzymatic products were identified by HPLC-MS. The expression profile of the UGT73C19 gene in soybean was analyzed by qRT-PCR. UGT73C19 was over-expressed in Arabidopsis thaliana by floral dipping method. Flavonoid content and composition were determined in seedlings and seeds in homozygous lines that showed the relatively high UGT73C19 expression level. 【Result】 Flavonoids in the leaves of soybean core germplasm showed significant differences in flavonoid composition and content in different varieties. Soybean core germplasm can be divided into 12 different types according to flavonoid composition. There was a positive correlation between the content of flavonoids and the expression level of UGT73C19 gene in the leaves of soybean core germplasm resources. The coding sequence of UGT73C19 gene was cloned,and the coding region was found to be 1482 bp, encoding a protein of 493 amino acids. The deduced UGT73C19 protein was found to have a conserved PSPG domain at the C-terminal. In vitro enzymatic activity analysis revealed that the recombinant UGT73C19 protein exhibited glycosyltransferase activity toward six flavonoid aglycones (kaempferol, quercetin, myricetin, apigenin, daidzein and genistein), and it showed the highest catalytic efficiency toward quercetin. The glycosylation sites were at the 5 and 7 hydroxy groups of flavonoid substrates, and the glycosylation substrates and sites of the recombinant UGT73C19 protein showed high diversity. It was found that the total flavonoid contents in the seedlings and seeds of the transgenic A. thaliana increased significantly, by 49% to 70% in leaves and 34% to 37% in seeds, in particular quercetin 3-O rhamnose in the seeds. 【Conclusion】 The recombinant UGT73C19 protein can catalyze the glycosylation of a group of flavonoid compounds and over-expression of UGT73C19 gene can increase the content of flavonols in plants like A. thaliana.

    Study on the Method for Identification Sesame Capsule Dehiscence Resistance and Evaluation of Capsule Dehiscence Resistance of the Core Collection
    LiSong SHI,Yuan GAO,DongHua LI,WenJuan YANG,Rong ZHOU,XiuRong ZHANG,YanXin ZHANG
    Scientia Agricultura Sinica. 2019, 52(20):  3520-3532.  doi:10.3864/j.issn.0578-1752.2019.20.003
    Abstract ( 399 )   HTML ( 30 )   PDF (1159KB) ( 396 )   Save
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    【Objective】 The mature sesame capsules are prone to dehisce, which causes yield loss, and it is an important factor influencing mechanized harvesting. Establishment of an easy, accurate, reliable and reproducible method for identification sesame capsule dehiscence (CD) resistance, will be helpful to discover germplasm with CD resistance and breed varieties resistant to CD, consequently promote the mechanization process of sesame production. 【Method】 After 2 weeks of the sesame enters mature stage, the capsules in the middle capsules part of the main stem were used in the identification CD resistance. Five representative germplasms with different CD resistance were used, the sample treatment method was determined by comparing the capsule opening width (COW) and the dehiscence angle C1 before and after drying, the best sampling part was selected by comparing the COW and the dehiscence angle C1 at each node of main stem. Using 308 core collections, total of 10 indices were measured and calculated, such as the capsule length (CL), capsule width (CW), capsule thickness (CT), capsule opening width (COW), capsule dehiscence depth (CDD), peel weight (PW), CDD/CL, PW/CL, dehiscence angle C1 and C2. Through statistical analysis including correlation analysis, principal component analysis, membership functions, and linear regression, the optimal index to evaluating CD resistance was screened out. The classification standard of CD resistance was determined according to the COW variation distribution on sesame core collections with diverse CD resistance. 【Result】 The capsule drying treatment was helpful to eliminate the error, and improve the identification accuracy. There was no significant difference between different plants of each material in the COW and dehiscence angle C1 of capsule from the middle 5 nodes, which were the best sampling parts. Based on statistical analysis of the 308 core collections, the optimal regression equation was established on the D value and individual indexes, that was D=-0.12+0.33X2+ 3.21X10, which showed that COW and PL/CL had significant effects on CD resistance, as the COW was highly significantly positive correlated with the dehiscence angle C1 (the correlation coefficient reached 0.8049), therefore the COW could be used in the identification of the CD resistance. The following classification criteria of sesame CD resistance were determined: Highly Resistant (COW≤0.7 cm), Resistant (0.7 cm<COW≤0.9 cm), Intermediate (0.9 cm<COW≤1.1 cm), Dehiscent (1.1 cm<COW≤1.5 cm), Prone to dehiscence (COW>1.5 cm). 【Conclusion】 When the sesame entered mature stage for 2 weeks or later, the middle capsules from 5 nodes in the middle part of the main stem was sampled and dried, then the COW were measured to accurately evaluate the CD resistance of sesame. The method established in this study was simple, with strong controllability and good repeatability, it was unaffected by environment, the result was reliable and can accurately reflect the CD resistance, therefore, the method can be used for high throughput identification of CD resistance of sesame germplasm. The CD resistance of 308 core collections were evaluated by this method, 11 germplasms with high CD resistance were identified.

    SPECIAL FOCUS: HIGH-YIELDING AND HIGH NUTRIENT EFFICIENT SPRING MAIZE IN NORTHEAST CHINA
    Integrated Management of High-Yielding and High Nutrient Efficient Spring Maize in Northeast China
    YongJun WANG,YanJie LÜ,HuiTao LIU,ShaoFeng BIAN,LiChun WANG
    Scientia Agricultura Sinica. 2019, 52(20):  3533-3535.  doi:10.3864/j.issn.0578-1752.2019.20.004
    Abstract ( 360 )   HTML ( 16 )   PDF (251KB) ( 336 )   Save
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    Effects of Sources Reduction on Accumulation and Remobilization of Dry Matter and Nitrogen, Phosphors and Potassium of Spring Maize Under Different Densities After Flowering
    YuJun CAO,Yang WU,ZhiMing LIU,Hong CUI,YanJie LÜ,FanYun YAO,WenWen WEI,YongJun WANG
    Scientia Agricultura Sinica. 2019, 52(20):  3536-3545.  doi:10.3864/j.issn.0578-1752.2019.20.005
    Abstract ( 405 )   HTML ( 18 )   PDF (463KB) ( 404 )   Save
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    【Objective】 The effects of source reduction on yield, dry matter, and nutrient accumulation and transport of nitrogen, phosphorus, and potassium under different density populations were discussed in this study, in order to provide more effective ways for further improvement of maize yield and nutrient use efficiency and to provide a reference for the selection and breeding of density-resistant varieties.【Method】 The cultivar Xianyu335 was used for experimental material, which was planted most popularly in local production. A split plot design with three replicates was used in the experiment. The main plot was different densities with 60 000 plants/hm 2 (conventional density) and 90 000 plants/hm 2(high density), respectively; The subplot was different sources reduction intensity by cutting the leaves of each plant by 1/2 (T1), 1/3 (T2), 1/4 (T3) and control (without cutting leaves) at silking stage. Dry matter weight and the contents of nitrogen, phosphorus, and potassium were determined, and dry matter and nutrient accumulation and transport were calculated. 【Result】 Under conventional planting density, the number of kernels per ear, 100-kernel weight, and grain yield were all decreased compared to the control under different levels of source reduction. Among them, the average yield of T1, T2 and T3 were 32.1%, 20.3% and 11.9% lower than that of the control in two years, respectively; Under high planting density, T3 treatment significantly increased the number of kernels per ear, which resulted in a significant increase in yield. The average yield in two years in T3 treatment was 7.7% higher than that of control. Compare with the control, the dry matter and the nutrients of nitrogen, phosphorus and potassium transport rate of vegetative organs were increased at different source reduction, the greater the source reduction, the higher the dry matter and nutrient transport rate. Under conventional planting density, the vegetative organs nutrients of nitrogen, phosphorus and potassium transport rate of T1, T2 and T3 were 25.4%, 19.1%, 10.7%, 14.3%, 9.8%, 5.2% and 19.0%, 10.7%, 8.4% higher than the control, respectively. While, under high planting density, the vegetative organs nutrients of nitrogen, phosphorus and potassium transport rate of T1, T2 and T3 were 17.1%, 12.8%, 5.8%, 12.6%, 8.0%, 3.6% and 14.9%, 11.3%, 3.9% higher than the control, respectively. Under conventional planting density, the differences of source reduction reduced the accumulation of nitrogen, phosphorus and potassium nutrients in grains. While, under high planting density, the accumulation of nitrogen, phosphorus and potassium nutrients in grains were increased at an appropriate source reduction level. The accumulation of nitrogen, phosphorus, and potassium were 11.1%, 6.9%, and 6.1% higher, respectively, than the control on average of two years under T3 treatment. But the nutrients of nitrogen, phosphorus and potassium under T1 and T2 treatments were 20.4%, 23.4%, 20.0% and 10.3%, 15.6%, 16.0% lower than the control, respectively.【Conclusion】 Leaf redundancy existed in dense maize population, reduction the amount of leaf sources appropriately (cutting all the leaves by 1/4 of whole plant) promoted the dry matter, nitrogen, phosphorus and potassium nutrients transport rate from vegetative organs to the grain, and increased the accumulation of nitrogen, phosphorus, and potassium nutrients in grains at mature stage. Therefore, increasing the density reasonably should be adopted in maize production. Meanwhile, the appropriate reduction of leaf source volume under high density population should be an effective way to further increase high yield and efficient use of nutrients in spring maize.

    Characteristics of Grain Yield and Nutrient Accumulation for Spring Maize Under Different Agronomic Management Practices
    JingChao YUAN,JianZhao LIU,Yao LIANG,WenJie ZHAN,HongXi ZHANG,ZiHao ZENG,HongGuang CAI,Jun REN
    Scientia Agricultura Sinica. 2019, 52(20):  3546-3558.  doi:10.3864/j.issn.0578-1752.2019.20.006
    Abstract ( 307 )   HTML ( 19 )   PDF (473KB) ( 301 )   Save
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    【Objective】 This research aimed to investigate the characteristics of grain yield, nutrient accumulation and transport of spring maize before and after flowering under different agronomic management practices, so as to provide theoretical and technical support for high yield and efficient production of spring maize. 【Method】 The field experiment was conducted from 2009 to 2012 in Gongzhuling of Jilin province. The hybrid “Xianyu335” was used as research material. During three consecutive years, five different agronomic management practices (CK, FP, Opt-1, Opt-2, and Opt-3) were set under the field conditions. The characteristics of dry matter accumulation, nutrient absorbing and transport were monitored before and after flowering of spring maize. The influence of grain yield was studied under different agronomic management practices. 【Result】 Reasonable densification, nutrient management and deep scarification were the key measures for high yield of spring maize. The result indicated Opt-3 was optimal under five different agronomic management practices. Compared with FP, the grain yield and dry matter accumulation of Opt-3 increased 13.9% and 22.4%, respectively. The number of maize ears in harvest stage contributed yield mostly, and the yield under Opt-3 was 34.3% higher than that under FP. Under the condition of same amount of fertilizer input between Opt-3 and FP, N, P and K accumulation of Opt-3 increased by 9.5%, 28.1% and 23.9% than that of FP, respectively. N, P and K translocation rate of Opt-3 increased by 47.7%, 21.7% and 45.0%, respectively. Partial productivity of N, P fertilizer increased by 14.0% and 4.4%, respectively. Compared with Opt-1, the grain yield of Opt-3 was further augmented by increasing planting density. When planting density was increased by 10 000 plant/hm 2, the grain yield increased 56-346 kg·hm -2. Compared with Opt-2, the efficiency of Opt-3 was improved through further optimization of fertilizer, and ANUE of Opt-3 increased 29.5%. Through fertilizer cost accounting, compared with FP, Opt-3 increased income by 2 218 yuan/hm 2. Compared with Opt-1, Opt-3 increased income by 290 yuan/hm 2. Compared with Opt-2, Opt-3 saved 367 yuan/hm 2.【Conclusion】 By reasonable densification to 70 000 plant/hm 2, optimized fertilizer (N 225 kg·hm -2-P2O5 90 kg·hm -2-K2O 90 kg·hm -2) and application period, organic fertilizer (1 500 kg·hm -2), added microelement fertilizer (150 kg·hm -2), combined with soil deep tillage, it was a relatively optimized integrated agronomic management mode, which could realize the synergistic improvement of spring maize yield and efficiency in the middle of northeast China.

    The Accumulation and Distribution Characteristics on Dry Matter and Nutrients of High-Yielding Maize Under Drip Irrigation and Fertilization Conditions in Semi-Arid Region of Northeastern China
    YunPeng HOU,LiLi KONG,HongGuang CAI,HuiTao LIU,YuShan GAO,YongJun WANG,LiChun WANG
    Scientia Agricultura Sinica. 2019, 52(20):  3559-3572.  doi:10.3864/j.issn.0578-1752.2019.20.007
    Abstract ( 609 )   HTML ( 46 )   PDF (550KB) ( 459 )   Save
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    【Objective】 Aiming at the accumulation dynamics and translocation and distribution characteristics of dry matter and nutrient of maize population among different cultivation modes under drip irrigation and fertilization conditions in semi-arid region of Northeastern China, this research provided the theoretical basis on high-yielding cultivation technique of spring maize under drip irrigation and fertilization conditions in the area.【Method】 The location experiment was conducted in Qian'an county in the western semi-arid region of Jilin province from 2014 to 2016 with three cultivation modes, including farmers' practice cultivation (FP), high-yielding cultivation (HY) and super high-yielding cultivation (SHY) under drip irrigation and fertilization conditions. Nonghua101 was chosen as experimental material. The characteristics of accumulation, translocation and distribution of dry matter and nutrient of maize population and the yield construction were studied among different cultivation modes under drip irrigation and fertilization conditions. 【Result】 The maize yield under HY and SHY modes were significantly higher than that under FP mode, with the average increment by 16.0% and 37.4%, respectively. The spike kernels and 100-kernels weight of HY and SHY modes were decreased than that of FP mode, but the spike numbers per unit area were significantly increased. Compared with FP mode, dry matter and N, P and K accumulations of maize population were significantly increased under HY and SHY modes from flowering stage to maturing stage, and the accumulation proportion of dry matter and N, P and K accumulations were increased in total growth period after flowering stage (the accumulation proportion of dry matter and N, P and K accumulations in total growth period after flowering stage were increased by 8.0%, 23.3%, 10.0%, 33.9% and 13.8%, 42.6%, 21.6%, 44.6%, respectively). Logistic equation analysis showed that the maximum and average increase rates of HY and SHY modes were 6.9%, 4.2% and 23.8%, 10.9% higher than that under FP mode, respectively, and the occurrence time of maximum rate was later. Compare with FP mode, HY and SHY modes reduced significantly nutrient translocation rate and contribution rate of translocation nutrients to kernels before flowering stage, and improved significantly contribution rate of accumulation nutrients to kernels after flowering stage of spring maize. Correlation analysis showed that the grain yield was significant or extremely significant correlated positively (r=0.7513-0.9840) with the dry matter and N, P and K accumulations around flowering stage of maize population, and the correlation coefficients after flowering stage were higher than them before flowering stage. 【Conclusion】 Compared with FP mode, HY and SHY modes improved the maximum and average increase rates of the dry matter in maize population, and postponed the occurrence time of the maximum increase rate of the dry matter. HY and SHY modes increased the dry matter and nutrient accumulations from flowering stage to maturing stage of maize, and enhanced significantly the contribution rate of accumulation nutrients to kernels after flowering stage. Therefore, the managing measures of increasing the planting density, controlling the total amount of N, P and K fertilizers and regulating fertilizer application during different stages could ensure the demand of N, P and K in the whole growth period of maize. This article provided an advantageous way for further promoting maize yield under drip irrigation and fertilization conditions in the semi-arid region of Northeastern China.

    Research on Optimum Phosphorus Fertilizer Rate Based on Maize Yield and Phosphorus Balance in Soil Under Film Mulched Drip Irrigation Conditions
    YunPeng HOU,LiChun WANG,Qian LI,CaiXia YIN,YuBo QIN,Meng WANG,YongJun WANG,LiLi KONG
    Scientia Agricultura Sinica. 2019, 52(20):  3573-3584.  doi:10.3864/j.issn.0578-1752.2019.20.008
    Abstract ( 394 )   HTML ( 13 )   PDF (525KB) ( 331 )   Save
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    【Objective】 In order to improve phosphorus efficiency and reduce environmental risk due to a large number of phosphorus application under mulched drip irrigation in northeast semi-arid region for maize production, a 3-year field experiment was conducted to investigate the effects of different phosphorus application rates on maize yield, phosphorus utilization efficiency and soil phosphorus supply ability, so as to provide scientific references for rational phosphorus fertilizer application in this region. 【Method】 The field experiment was conducted in semi-arid maize production region of Jilin province (Qian'an county) from 2015 to 2017. Six treatments of phosphorus application rate (P2O) were designed in the field experiments, including 0 (P0), 40 kg·hm -2 (P40), 70 kg·hm -2 (P70), 100 kg·hm -2 (P100), 130 kg·hm -2 (P130) and 160 kg·hm -2 (P160), which were used for the calculation of phosphorus uptake, phosphorus utilization efficiencies and apparent phosphorus balance in the soil-crop system. The measurement indexes contained maize yield and its components, phosphorus content of plant at mature stage and soil available phosphorus concentration. 【Result】 The result showed that the maize yield with phosphorus application were significantly increased by 6.2%-21.2% (2015), 9.0%-20.6% (2016) and 12.9%-30.3% (2017) respectively, and increment by 9.2%-23.9% in average three years. The yield was enhanced by increasing grains per ear, 100-kernel weight and harvest index by applying phosphorus fertilizer. Maize yield increased at first and decreased later with increasing of phosphorus application rate, and the highest yield value was found under P100 treatment. Phosphorus recovery efficiency and partial productivity declined, however, phosphorus agronomic efficiency increased at first and decreased later with increasing of phosphorus application rate. Available phosphorus content in soil layer (0-40 cm) was improved with the increasing of phosphorus application rate and period compared with P0 treatment, and the content under P100 treatment was very close to its initialization value. The apparent phosphorus balance in soil was negative in the P0, P40 and P70 treatments after a three-year continuous maize-cropping, and the phosphorus deficient amount was decreased with the increment of phosphorus application rate. While the apparent phosphorus balance in soil was positive under the P100, P130 and P160 treatments, and phosphorus surplus amount was increasing with the increment of phosphorus application rate. When surplus rate was 0, phosphorus application rate, maize yield, available phosphorus content in 0-20 cm and 20-40 cm soil, phosphorus recovery efficiency, agronomic efficiency and partial productivity were 92.4 kg·hm -2, 12 497 kg·hm -2, 34.6 mg·kg -1, 28.4 mg·kg -1, 24.1%, 21.9 kg·kg -1 and 146.1 kg·kg -1, respectively, by simulating between phosphorus application rate (y1), soil available phosphorus content (y2), phosphorus utilization efficiency (y3) and surplus rate (x), respectively. These results were similar to maize yield, soil available phosphorus content and phosphorus utilization efficiency under the maximum yield under the P100 treatment. The optimum phosphorus application rate was at the range of 88-97 kg·hm -2 under 95% confidence levels, when theoretical surplus rate was 0. 【Conclusion】 The results suggested that the recommended phosphorus application rate was at the range of 88-97 kg·hm -2, which could not only ensure higher maize yield, but also keep soil phosphorus balance under this experimental conditions. The research provided phosphorus fertilizer management for both high-yielding maize production and friendly environment under mulched drip irrigation conditions in northeast semi-arid region of Jilin province.

    PLANT PROTECTION
    In vitro Evaluation of Strawberry Germplasm Resources for Resistance to Anthracnose
    YongChao HAN,XiangGuo ZENG,FaYun XIANG,Cong GUO,QingHua ZHANG,FengYing CHEN,Wei GUAN
    Scientia Agricultura Sinica. 2019, 52(20):  3585-3594.  doi:10.3864/j.issn.0578-1752.2019.20.009
    Abstract ( 391 )   HTML ( 19 )   PDF (948KB) ( 326 )   Save
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    【Objective】 The objective of this study is to evaluate the anthracnose resistance level of 71 strawberry accessions including 24 accessions from 12 Fragaria species, 41 cultivars from Fragaria × ananassa and 6 interspecific hybrids, and to provide a basis for the utilization of strawberry germplasm resources in resistance breeding.【Method】 Colletotrichum fructicola isolate Gwha-1, which was isolated from strawberry petiole, was used as inoculation pathogen. The suspension of C. fructicola (1×10 6 conidia/mL) was evenly inoculated on the leaf surface and petiole of strawberry leaves by in vitro inoculation method. Inoculated leaves were moisturized at 28℃ for 4 days, and then the incidence of each leaf was investigated. The lesion number on leaf surface, the largest lesion diameter on leaf surface, and the maximum lesion length on petiole were counted. Correlation analysis was performed on the lesion length on petiole, the lesion number and the lesion diameter on leaf surface of different materials using IBM SPSS 15.0 software. The disease severity of each leaf was ranked according to the lesion length on petiole. The disease index of each material was calculated, and the anthracnose resistance of the tested materials was evaluated based on the disease index of petiole after inoculation with C. fructicola isolate Gwha-1. The general linear model procedure (PROC GLM) in SAS was used to analyze the differential significance (P<0.05) among five strawberry species, including F. × ananassa (41 accessions), F. mandschurica (3 accessions), F. viridis (4 accessions), F. nilgerrensis (3 accessions), and interspecific hybrids (6 accessions). Species were used as fixed factors and tested materials as random factors.【Result】 There was no completely immune material to anthracnose caused by C. fructicola in the tested materials, and all materials had different degrees of disease incidence after 4 days of inoculation with C. fructicola isolate Gwha-1. The comparison of different materials showed that the lesion length on leaf petiole was positively correlated with the lesion number on leaf and the lesion diameter on leaf surface after inoculation. According to the lesion length on petiole after inoculation with C. fructicola, the anthracnose resistance of the tested materials could be distinguished. The numbers of materials with anthracnose resistance level of high resistance, resistance, medium resistance, medium susceptibility, susceptibility and high susceptibility were 17, 20, 21, 3, 6 and 4, respectively, 81.7% of the tested materials had medium resistance, resistance or higher resistance level to anthracnose caused by C. fructicola. ‘3 Gongzhu’ ‘Senga Sengana’ ‘Darselect’ ‘Allstars’ ‘Kaorino’ ‘Veestar’ and ‘Jingzangxiang’ in the F. × ananassa, and ‘Tokun’ in interspecific hybrids had high resistance to anthracnose. In the wild species of strawberry, the resistance level of all the F. mandschurica, F. viridis and F. orientalis tested materials was high resistance, and the disease index of F. mandschurica and F. viridis was significantly lower than that of F. × ananassa. 【Conclusion】 The anthracnose resistance of 71 strawberry resources was evaluated. Seven cultivars of high resistance to anthracnose were selected from the cultivated strawberries, including ‘3 Gongzhu’ ‘Senga Sengana’ ‘Darselect’ ‘Allstar’ ‘Kaorino’ ‘Veestar’ and ‘Jingzangxiang’. There are high anthracnose resistant resources in F. mandschurica and F. viridis. Their resistance level to anthracnose is significantly higher than that of F. × ananassa, which can be used as an antigen source of anthracnose in interspecific hybridization.

    Development of 30% Clothianidin·Pyraclostrobin·Difenoconazole Flowable Concentrate for Seed-Coating and Its Application Effect in Peanut Field
    HaiChao CAO,QingShun LIU,HaiXiu BAI,Jun HAN,ShiLing YANG,Ming XUE,Feng LIU
    Scientia Agricultura Sinica. 2019, 52(20):  3595-3604.  doi:10.3864/j.issn.0578-1752.2019.20.010
    Abstract ( 389 )   HTML ( 19 )   PDF (2727KB) ( 271 )   Save
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    【Objective】 The objective of this study is to evaluate the safety of 30% clothianidin·pyraclostrobin·difenoconazole flowable concentrate for seed-coating (FS) on the growth of peanut (Arachis hypogaea) and its application potential in peanut soil-borne diseases and underground pests control.【Method】 30% clothianidin·pyraclostrobin·difenoconazole flowable concentrate for seed-coating was prepared and its pH, viscosity, suspension rate, cold and heat storage stability and the change of particle size distribution of agent after cold and heat storage tests were measured. 30% clothianidin·pyraclostrobin·difenoconazole FS was used to treat peanut seeds in the greenhouse with three doses of 200, 400 and 800 g a.i./100 kg seeds. At 14 days after sowing, the seedling emergence time and plant height, root length, fresh weight of stalk, leaf and root, and plant dry weight were measured to evaluate the safety of seed-coating for peanut seedling emergence and growth. In the field, three doses of 100, 200 and 400 g a.i./100 kg seeds were set for peanut seed-coating, and three efficacy trials in different places were conducted in two years. The 25% thiamethoxam·fludioxonil·metalaxyl-M FS (Maishuping) was selected as control agent.【Result】 The quality of 30% clothianidin·pyraclostrobin·difenoconazole flowable concentrate for seed-coating conformed to the standard GB/T17768—1999 of flowable concentrate for seed-coating of pesticide product. In the greenhouse pot experiment, the agent was safe for peanut seedling emergence and growth with 200, 400 and 800 g a.i./100 kg seeds. Field trials were conducted in 2016 with three doses of 100, 200 and 400 g a.i./100 kg seeds, the control efficacy on peanut crown rot was 95.16%, 97.98% and 98.79%, on peanut root rot was 90.97%, 92.26% and 92.90%, and against Aphis medicaginis was 79.74%, 92.48% and 94.13%, respectively, and the control efficacy on pests increased with the increase of dose. Compared with the blank control treatment, the peanut emergence rate increased by 10.25%-13.21%, and the peanut yield increased by 683.75-1 234.12 kg·hm -2. Therefore, 200 g a.i./100 kg seeds was selected as the field recommended dose in 2017. In the two field trials in 2017, which conducted in Xintai and Taian of Shandong Province, the control efficacy on peanut crown rot was 81.12% and 95.83%, on peanut root rot was 71.74% and 92.93%, and against cutworm in Xintai and on peanut stem rot in Taian was 93.33% and 87.29%, respectively. Compared with the blank control treatment, the peanut emergence rate increased by 4.23% and 10.75%, and the yield increased by 1 146.45 and 1 715.70 kg·hm -2, in Xintai and Taian trials, respectively.【Conclusion】 30% clothianidin·pyraclostrobin·difenoconazole flowable concentrate for seed-coating has good control efficacy on peanut crown rot, root rot, stem rot, A. medicaginis and cutworms, it is safe for the peanut growth and emergence and can improve the peanut yield. Therefore, the seed-coating has a good promotion prospect.

    SPECIAL FOCUS: SOIL WATER AND FERTILIZER MANAGEMENT IN GREENHOUSE VEGETABLE FIELDS
    Mechanisms and Managements of Water and Fertilizer Synergy in Greenhouse Vegetable Fields
    XuePing WU, YinKun LI
    Scientia Agricultura Sinica. 2019, 52(20):  3605-3610.  doi:10.3864/j.issn.0578-1752.2019.20.011
    Abstract ( 265 )   HTML ( 15 )   PDF (311KB) ( 290 )   Save
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    Effects of Drip Irrigation Water and Fertilizer Integration Combined with Organic Fertilizers on Soil N2O Emission and Enzyme Activity
    YaJing XI,JunYu WANG,YinKun LI,XuePing WU,XiaoXiu LI,BiSheng WANG,ShengPing LI,XiaoJun SONG,CaiCai LIU
    Scientia Agricultura Sinica. 2019, 52(20):  3611-3624.  doi:10.3864/j.issn.0578-1752.2019.20.012
    Abstract ( 354 )   HTML ( 24 )   PDF (2001KB) ( 298 )   Save
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    【Objective】 This paper mainly studied the dynamic changes of soil N2O emission and the activities of urease (UR), nitrate reductase (NR), nitrite reductase (Ni R) and hydroxylamine reductase (Hy R) under the condition of drip irrigation water and fertilizer integration by applying different amounts of inorganic nitrogen to organic nitrogen, and analyzed the soil N2O emission characteristics of every treatment and the effects of soil UR, NR, Ni R and Hy R activities on soil N2O emissions, the purpose of this research was to reveal the influence mechanism of N2O emission process under the integration of drip irrigation water and fertilizer.【Method】 The treatments consisted of CK (no nitrogen application), N1 (200 kg·hm -2 organic nitrogen), N2 (200 kg·hm -2organic nitrogen + 250 kg·hm -2 inorganic nitrogen), and N3 (200 kg·hm -2 organic nitrogen + 475 kg·hm -2inorganic nitrogen). Using static-chamber method, the soil N2O emission, enzyme activity, soil temperature and humidity during the growth period of tomato were monitored.【Result】 The integration of water and fertilizer in drip irrigation showed that the N2O emission peak of every treatment appeared at the first day after fertilization + irrigation, and decreased continuously with the passage of time. The N2O emission flux range under different treatments was 0.98-1544.79 μg·m -2·h -1. The total N2O emissions during the growth period of tomato under different treatments had significant differences among each treatment, which were N3 ((7.13±0.11) kg·hm -2) >N2 ((4.87±0.21) kg·hm -2) >N1 ((2.54±0.17) kg·hm -2) >CK ((1.56±0.23) kg·hm -2). Compared with N3, the total soil N2O emissions from N1 and N2 decreased by 64.38% and 31.70%, respectively. During the growth period of tomato, the characteristics of seasonal emission of N2O changed obviously, which revealed high in autumn and low in winter. The activity of soil nitrogen-related enzymes increased with the increase of nitrogen application rate. The soil N2O flux was positively correlated with 5 cm soil temperature, 0-10 cm soil nitrate nitrogen content, soil NR activity and soil Hy R activity (P<0.01).【Conclusion】 Under the integration of drip irrigation and water and fertilizer, soil N2O mainly came from the nitrification process, which reduced the N2O emissions generated by the denitrification process. Considering the factors such as tomato yield, quality and N2O emission, it was recommended to apply 200 kg·hm -2organic nitrogen +250 kg·hm -2 inorganic nitrogen, 75 kg·hm -2 P2O5 and 450 kg·hm -2 K2O in northern greenhouse autumn-winter tomato.

    Effect of Organic Partial Replacement of Inorganic Fertilizers on N2O Emission in Greenhouse Soil
    YaJing XI,DongYang LIU,JunYu WANG,XuePing WU,XiaoXiu LI,YinKun LI,BiSheng WANG,MengNi ZHANG,XiaoJun SONG,ShaoWen HUANG
    Scientia Agricultura Sinica. 2019, 52(20):  3625-3636.  doi:10.3864/j.issn.0578-1752.2019.20.013
    Abstract ( 362 )   HTML ( 14 )   PDF (532KB) ( 299 )   Save
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    【Objective】 Under the condition of replacing the inorganic fertilizer part with the same amount of nitrogen, the purpose of this study was to study the emission characteristics of greenhouse tomato soil N2O and to explore the environmental factors affecting N2O emissions, which could provide data support and theoretical basis for the N2O emission inventory of the greenhouse vegetable system and its emission reduction potential.【Method】 Taking greenhouse autumn-winter tomato as the research object, the static-chamber method was used to monitor the soil N2O emission, soil temperature and soil water content during the growth period of tomato. The experiment was set 4 treatments, including non-fertilization (CK), single application of organic fertilizer (MN), single application of inorganic fertilizer (CN), and organic partial replacement of inorganic fertilizers (CMN).【Result】 Under the same nitrogen application rate, the total N2O emission under CMN was 4.05 kg·hm -2. Compared with CN and MN, the total N2O emission under CMN decreased by 45.1% and 33.2% , respectively; the emission factor of soil N2O was reduced by 50.0% and 37.5%, respectively; the emission intensity was reduced by 50.0% and 42.1%, respectively. The peak soil N2O of all treated appeared on the first day after fertilization and irrigation, and the discharge was mainly concentrated within 5 days after fertilization and irrigation. The N2O emission flux in greenhouse tomato soil showed significant or extremely significant correlation with the ground temperature of 0-5 cm soil, and showed a significant or extremely significant logarithm function relationship with soil water-filled porosity (WFPS). The peak of soil N2O emission under different fertilization treatments appeared in 60%~80% soil-filled porosity.【Conclusion】 The relationship between the growth and decline of N2O emissions in greenhouse tomato soil was reflected in the changes of temperature and humidity and the type of nitrogen fertilizer input. Reasonable emission reduction measures should be considered based on the above factors. Partial replacement of inorganic fertilizers with organic fertilizers was an important means to increase greenhouse tomato production, to reduce N2O emissions intensity, factor and total N2O emissions increase fertilizer utilization, and to achieve zero growth of fertilizers.

    Effect of Applying Chicken Manure and Phosphate Fertilizer on Soil Phosphorus Under Drip Irrigation in Greenhouse
    ZhiPing LIU,XuePing WU,RuoNan LI,FengJun ZHENG,MengNi ZHANG,ShengPing LI,XiaoJun SONG
    Scientia Agricultura Sinica. 2019, 52(20):  3637-3647.  doi:10.3864/j.issn.0578-1752.2019.20.014
    Abstract ( 356 )   HTML ( 7 )   PDF (469KB) ( 280 )   Save
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    【Objective】 Aiming at the problem of phosphorous accumulation in greenhouse soil, the effects of applying chicken manure and phosphorus fertilizer on phosphorus accumulation in soil under drip irrigation were studied.【Method】 The solar greenhouse in North China Plain using drip irrigation was taken as research object. Five treatments were designed, including no fertilizer (CK), single phosphate (P1), single chicken manure (OM), chicken manure and reduced phosphate fertilization (OM+P1), chicken manure and habitual phosphate fertilization (OM+P2), to reveal the enrichment and transformation, migration and distribution in vertical section of soil at different growth stages and availability of inorganic phosphate form in soil.【Result】 The results showed that the combination of chicken manure and phosphate fertilizer significantly increased the accumulation and residue of total phosphorus, available phosphorus (Olsen-P) and inorganic phosphorus in soil. In the soil layer of 0-20 cm, total phosphorus content decreased with the development of cucumber growth period, highest in seeding stage and lowest in late fruiting stage period. Under different fertilization treatments, total phosphorus contents were significantly different, and the sequence of each growth period was OM+P2 treatment>OM+P1 treatment>P1 treatment>OM treatment>CK treatment. The Olsen-P contents at different levels in the soil profile varied greatly. In seedling stage, the range was 44.43-86.08 mg·kg -1 at soil of 0-20 cm, 6.51-10.05 mg·kg -1 at soil of 20-40 cm, and there was very little variability in soil layer lower than 40 cm. The effect of water on the movement of phosphorus was slight under the condition of drip irrigation in greenhouse. So Olsen-P mainly concentrated in the soil layer of 0-20 cm, which accounted for 68.76-87.78% of the available phosphorus in soil profile of 0-100 cm in each growth period. Compared with CK, the other treatments increased the proportion of Olsen-P in total phosphorus by 1.23%-2.47%. The sequence of inorganic phosphorus content of different forms in soil layer of 0-20 cm was Ca10-P>Ca8-P>O-P>Ca2-P>Al-P>Fe-P, among which, the proportion of Ca-P was the highest (79.55%-83.35%). As the amount of phosphorus fertilizer increased, so did the accumulation of phosphorus. The contents of Ca8-P, Ca2-P, Al-P, Fe-P and Ca10-P under fertilization treatments were all significantly higher than that under CK, with Ca8-P increased the most, followed sequentially by Ca2-P, Al-P and Fe-P. Phosphate fertilizer would be converted into Ca8-P through Ca2-P soon after it was applied into the soil, which accumulated in the soil in a slow manner. Among all forms of inorganic phosphorus, Ca8-P accumulated the most, Al-P and Fe-P also accumulated to a certain extent.【Conclusion】 Traditional excessive fertilization caused phosphorus remaining in the soil in the forms of Ca8-P, Al-P and Fe-P, resulting in the accumulation of soil phosphorus and waste of phosphorus fertilizer. On the basis of 30,000 kg·hm -2 chicken manure, adding phosphate fertilizer had no significant effect on increasing yield but obviously increased the residual accumulation of phosphorus. If only chicken manure was applied, the dosage should not exceed 30 000 kg·hm -2. If inorganic phosphate fertilizer was combined, the amount of chicken manure should be reduced, while the inorganic phosphate fertilizer rate should be less than 300 kg·hm -2. The specific amount and proportion of fertilizer application need further study and discussion.

    Optimization Management of Water and Fertilization for Winter-Spring Cucumber Under Greenhouse Drip Irrigation Condition
    RuoNan LI,ShaoWen HUANG,JianShuo SHI,LiYing WANG,JiWei TANG,HuaiZhi ZHANG,Shuo YUAN,FengZhi ZHAI,YanLi REN,Li GUO
    Scientia Agricultura Sinica. 2019, 52(20):  3648-3660.  doi:10.3864/j.issn.0578-1752.2019.20.015
    Abstract ( 344 )   HTML ( 14 )   PDF (488KB) ( 264 )   Save
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    【Objective】 This study focused on determining the appropriate soil water parameters and the potential of soil nitrogen supply at different growth stages of drip irrigated cucumber to optimize the water and fertilizer management and to guarantee the sustainable green and high yield production.【Method】 A plot experiment was conducted inside a greenhouse using cucumber as tested material during the winter-spring growing season. Drip irrigation with 3 water amounts (W1, W2 and W3) and 3 fertilizer amounts (F1, F2 and F3) were designed to form 9 combination treatments. The impacts of the irrigation and fertilization amounts on the fruit yield, qualities, nutrient uptakes, water and fertilizer use efficiencies, soil water contents and nutrient availabilities were analyzed in the study. The response relationships between the marketable yields , the root zone soil water and available nitrogen contents at different growth stages were built.【Result】 (1) Compared with W1, the total marketable yields were increased by 11.1%-12.8% under W2 and W3. The marketable yields were deceased by 10.4%-17.7% under W3 during the 1st-2nd fertigation managements, but which increased by 10.8%-26.2%, 21.2%-40.3% and 33.5%-46.4% under W2 and W3 during the 6th-8th, 10th-12th and 14th-16th fertigation managements, respectively. The rootzone (0-40 cm soil layer) soil water contents were increased by 4.2-6.4 percentage point by maintaining at the soil relative water content of 79%-87% uder W2 and W3 and the N, P2O5 and K2O uptakes by 17.9%-20.2%, 28.3%-36.3% and 25.9%-33.7%, respectively. However, the rootzone nitrate nitrogen contents were decreased by 9.1%-68.0% under W2 and W3, the water use efficiency by 31.1%-49.3%, and the fruit soluble solids, nitrate, soluble sugar and Vc contents by 7.4%-10.1%, 0.9%-5.4%, 5.9%-6.2% and 5.5%-12.8%, respectively. (2) Compared with F1, the total marketable yields were increased by 4.0%-7.9% under F2 and F3. The rootzone (0-40 cm soil layer) nitrate nitrogen contents were increased by 38.0%-162.0% under F2 and F3, and the N, P2O5 and K2O uptakes by 9.7%-13.1%, 7.9%-11.8% and 12.6%-17.3%, respectively. However, the fruit nitrate contents increased by 5.5%-14.6% under F2 and F3 and the partial factor productivities were deceased by 32.1%-47.8%. (3) From the view of whole growth period, W2F2 was recommended to drip irrigated cucumber because of the relatively higher yield, water and fertilizer use efficiencies and qualities, and lower residual soil nitrogen.【Conclusion】 For greenhouse cucumber with a target yield of 170-180 t·hm -2, the appropriate soil relative water contents were recommended as 63%, 78%, 82% and 85% during the March 21th- April 20th (the initial harvesting stage), April 21th-May 20th (the early vigorous harvesting stage), May 21th-June 20th (the vigorous harvesting stage) and June 21th-July 10th (the late harvesting stage), respectively. The corresponding low limits of soil relative water contents were recommended as 61%, 73%, 78% and 81%, respectively. The suitable rootzone nitrate nitrogen should be maintained at 25-40 mg·kg -1 during the yield formation.

    FOOD SCIENCE AND ENGINEERING
    Quality Change and Bacteria Succession of Dried Carrot Stored at Different Water Activities
    WenJian YANG,HaoLiang PU,LiuQing WANG,QiuHui HU,Fei PEI
    Scientia Agricultura Sinica. 2019, 52(20):  3661-3671.  doi:10.3864/j.issn.0578-1752.2019.20.016
    Abstract ( 321 )   HTML ( 13 )   PDF (4224KB) ( 578 )   Save
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    【Objective】 The aim of this study was to explore quality change and exogenous bacteria succession in dried carrots at different water activities (aw), so as to provide a theoretical basis for controlling quality deterioration and prolonging shelf life of dried carrots during storage. 【Method】 Dried carrots with uniform size at different aw levels of 0.43, 0.67, 0.78 and 0.84, respectively were stored for 50 d in sealed desiccators. Hardness, microstructure, content of β-carotene and flavor components were then determined, and the changes of exogenous bacteria abundance and succession were also analyzed. 【Result】 Results suggested that lactic acid bacteria were the dominant bacteria in dried carrots. After 50 d storage, the relative abundance of Bacillus spp. in dried carrots stored at aw = 0.43 was significantly higher than that of other groups. However, higher aw levels promoted the growth of Pediococcus spp., Staphylococcus spp. and Lactobacillus spp. Moreover, the higher aw levels reduced the hardness and adhesion of dried carrots microstructure and aggravated the loss of β-carotene, a typical nutrient in dried carrots. E-nose analysis showed that higher aw caused a decrease in olefins and ketones contents, indicating loss of characteristic flavors in dried carrots. On the other hand, the increase of amines content was attributed to growth of lactic acid bacteria. 【Conclusion】 Higher aw promoted the growth of Pediococcus spp., Staphylococcus spp. and Lactobacillus spp., caused a decline in hardness and microstructure adhesion of dried carrots, and accelerated the loss of β-carotene, as well as the deterioration of characteristic flavors.

    The Extracellular Enzymes Activity of F1 Generations and Single-spore Isolations in Agrocybe salicacola Strain YAAS711
    HuiMing ZHOU,YongChang ZHAO,HongMei CHAI,YanZhen ZHANG
    Scientia Agricultura Sinica. 2019, 52(20):  3672-3684.  doi:10.3864/j.issn.0578-1752.2019.20.017
    Abstract ( 214 )   HTML ( 13 )   PDF (478KB) ( 187 )   Save
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    【Objective】 The objective of this study was to explore the changes in activities of extracellular enzymes (EEA) of single-spore isolations and its self-crossing individuals from Agrocybe salicacola YAAS711 and to provide evidence for its genetic breeding. 【Method】 Eighteen single-spore monokaryons and 22 dikaryons from self-crossing progeny of A. salicacola YAAS711 were used as the test materials. The activities of CMCase, filter paper cellulase, β-glucanase, hemicellulase, amylase, protease, laccase, polyphenolase and peroxidase of all test strains were determined by 3,5-dinitrosalicylic acid (DNS), Folin methods and guaiacol method, and correlation analysis were carried out between the 9 EEs with mycelial growth rate, polarities and mating factors.【Results】 The results of 9 EEs showed that most of the both monokaryons and dikaryons had higher activities of amylase, filter paper cellulase, hemicellulose, β-glucanase, CMCase and protease, but their activities of peroxidase, polyphenolase and laccase were low. The mycelial growth rate of monokaryons and dikaryons had a certain degree of correlation with the average activity of 9 EEAs. Compared with the dikaryons derived from the combination of “fast-fast” growth rate of monokaryons, the dikaryons derived from the combination of “fast-slow” growth rates of monokaryons had higher EEAs, except hemicellulase, protease and polyphenol oxidase activities. However, there were no rules to follow, when it came to the combination of dikaryons from the cross of type II monokaryons. The indirect effect of polyphenolase on the mycelial growth rate of monokaryons was greater than that of laccase, but the combined effect of laccase on the mycelial growth rate of monokaryons was the largest. The synergistic effect among EEs had little effect on the mycelial growth rate of dikaryons, among them, laccase had the greatest direct effect on its mycelial growth rate. Multiple comparisons showed that the effect of polarity on EEs was greater than that of mating factors at a significant level of 0.05.【Conclusion】 In short, there was a significant correlation between the anomalies of the mycelial growth rate of the monokaryons from same polarity single spore isolations and the EEAs of F1 generations deriverd from these monokaryons in A. salicacola strain YAAS711. The EEAs of type I strains had same rule, but the differences were existed in some type II monokaryons and the dikaryons. There were certain correlation between the growth rate of monokaryons, EEAs and polarity, there were no direct correlation between mating factors and EEAs.

    ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT
    Evaluation of Apparent Metabolic Energy, Nitrogen Corrected Metabolic Energy, Biological Value of Protein and Ileal Digestibility of Amino Acid of Yeast Hydrolysate for Broilers
    Wei ZHANG,JinJun DAI,XueHai YANG,JinTao WEI,MingXin CHEN,JunPeng HU,ShaoWen HUANG
    Scientia Agricultura Sinica. 2019, 52(20):  3685-3694.  doi:10.3864/j.issn.0578-1752.2019.20.018
    Abstract ( 236 )   HTML ( 18 )   PDF (511KB) ( 150 )   Save
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    【Objective】 The purpose of this study was to evaluate the apparent metabolic energy, nitrogen-corrected apparent metabolic energy, ileal apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate in broilers, so as to provide the reference for the wide application of yeast hydrolysate in broiler diets. 【Method】 A total of 160 Cobb white-feathered broilers at 18 days old with no difference in body weight were randomly divided into the control group and experimental group. There were 8 replicates in each group, and 10 chickens with half male and half female were in each replicate. The control group was fed a nitrogen-free diet consisting of corn starch, glucose, fiber and soybean oil, and the experimental group was fed a semi-homozygous diet using yeast hydrolysate as the sole crude protein source. Furthermore, the control group and the experimental group were fed with 0.5% titanium dioxide, respectively, as an exogenous indicator. During the whole experiment, free feeding was available for broilers, feces were collected on 22-24 days using total fecal collection method, and the feed intake of broilers was counted. Further, the apparent metabolic energy of yeast hydrolysate and nitrogen-corrected apparent metabolic energy were calculated by measuring the total energy and nitrogen content in both diets and feces of broilers. After26 days of experiment, the latter half of ileum was dissected under anesthesia, the chime was taken out, and the contents of amino acids and titanium dioxide in both diet and ileal chyme were measured to calculate the apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate. 【Result】 (1) The total energy value of yeast hydrolysate was 18.19 MJ·kg -1, the apparent metabolic energy value was 11.22 MJ·kg -1, and the nitrogen-corrected apparent metabolic energy was 10.17 MJ·kg -1. Effective energy was equivalent to that of common soybean meal. (2) Crude protein content of yeast hydrolysate was 41.7%, and total amino acid was 36.97%. The ratio of essential amino acid to dispensable amino acid was 44:56, which was close to that of common soybean meal. The limiting amino acids of yeast hydrolysate were Met, Met+Cys, Arg, Leu, Ile, Phe+Tyr, Val, His, lys, Thr and Trp, which were different from soybean meal. (3) The ileal apparent amino acid digestibility, standard ileal amino acid digestibility and total intestinal apparent amino acid digestibility of yeast hydrolysate were all higher than 70%. The available limiting amino acids were Met, Met+Cys, Arg, Leu, Ile, Thr, Phe+Tyr, His, Lys, Val, and Trp. Methionine and arginine were the first and the second limiting amino acids, and leucine and isoleucine were the third and the fourth limiting amino acids, respectively. Threonine was poorly available, and was regarded as the fifth restrictive available amino acid. In addition, the limiting amino acids of yeast hydrolysate were quite different to soybean meal. 【Conclusion】 Yeast hydrolysate was a kind of protein feed material. Its protein content and effective energy value were similar to soybean meal, but its amino acid composition and availability were quite different to soybean meal. Therefore, in the application of yeast hydrolysate in broiler diet, it was necessary to consider the need of supplementing different amino acids or mixing different protein feeds to balance amino acids.

    Determination of 146S Antigen in Inactivated Foot-and-Mouth Disease Vaccine by Size-Exclusion High-performance Liquid Chromatography and Quality Evaluation of Vaccine
    YuanYuan ZHU,Yuan XU,XingQi ZOU,YanLi YANG,LiLi LIU,JianQing WAN,Cui LI,Lu XU,QianYi ZHANG,YingJu XIA,Zhao WANG,HongWu LANG,Qin WANG,SongPing ZHANG,QiZu ZHAO
    Scientia Agricultura Sinica. 2019, 52(20):  3695-3704.  doi:10.3864/j.issn.0578-1752.2019.20.019
    Abstract ( 531 )   HTML ( 30 )   PDF (866KB) ( 249 )   Save
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    【Background】 As vaccine manufacturers and regulatory departments, the quality evaluation method of foot-and-mouth disease (FMD) vaccine is particularly important in quality control, where the 146S antigen is the key index. For the quantification of 146S antigen in FMD vaccine, sucrose gradient density centrifugation (SGDC) is recognized as a classical method but the process is complex, time-consuming and poorly repeatable, which affect the quality monitor of vaccines. Size-exclusion high-performance liquid chromatography (SE-HPLC) is previously reported as a simple, rapid, highly automated and efficient technology for analysis of 146S content. 【Objective】 A method of 146S antigen determination in inactivated FMD vaccine by SE-HPLC has been preliminarily established. However, the applicability, repeatability and effectiveness of this method are unknown in the FMD vaccines produced by different manufacturers with different concentration and purification processes. Hence, it is imperative to confirm the universality of the SE-HPLC method.【Method】 Here, the standard curve and regression equation of SE-HPLC method were established with FMD 146S antigen standard, which were used for 146S antigen detection of samples. Moreover, using five samples with 1, 2, 4, 8 and 16 times dilution of 146S antigen standard and 22 batches of vaccine randomly selected in the market, the 146S antigen was detected by SE-HPLC and SDGC respectively, and the correlation between the two methods was analyzed. Further, 134 batches of inactivated FMD vaccines products from different manufacturers in the market were detected three times each for 146S content by SE-HPLC. By analysis of chromatogram specificity of SE-HPLC method and relative standard deviation of 146S content, we confirmed its repeatability and reliability in evaluating all types of vaccine. Finally, 146s content was operated for the quality of FMD vaccines in the market. 【Result】 The standard curve of SE-HPLC method showed good linearity between peak area and concentration of FMD 146S antigen standard (R 2=0.9981, n=8).The detection results of 146S content in 5 diluted 146S antigen standards and 22 batches of FMD vaccine demonstrated that there was a highly positive correlation between SDGC and SE-HPLC methods (RS 2=0.9994, nS=5;Rv 2= 0.9602, nv=22). Among 134 batches of vaccines, the vaccine batches with 146S content relative standard deviation RSD<5% accounted for 81.34%, 72.22%, 85.53% and 80.00% of the total vaccine batches (134 batches), total monovalent vaccine batches (18 batches), total bicomponent and bivalent vaccine batches (76 batches) and total trivalent vaccine batches (40 batches), respectively. The vaccine batches with 146S content RSD≤10% accounted for 97.76% of the total vaccine batches (134 batches). The SE-HPLC method for detection 146S content in FMD vaccines performed good repeatability, and best repeatability appeared in 2-4μg·mL -1146S content of the vaccines. Target peaks could be detected in all batches of vaccine, the average peak starting time, peak and peak falling time of objective chromatographic peaks were 11.58 min, 12.90 min and 14.93 min after HPLC sampling. The average retention of peak was 3.36min. The average 146S content was 1.11-80.36μg·mL -1 in all vaccines, 2.07 μg·mL -1 in monovalent vaccines, 2.40 μg·mL -1 in bivalent vaccines, 2.85 μg·mL -1in bicomponent vaccines and 13.14 μg·mL -1 in trivalent vaccines respectively.【Conclusion】 These results provided proof that SE-HPLC assay was universal, highly repeatable, reliable, rapid and simple for detection 146S content in various types of current inactivated FMD vaccines in the market, which could be used to monitor and evaluate the quality of the vaccine. FMD vaccines in the market had high 146S content and good vaccine quality.

    RESEARCH NOTES
    Molecular Cloning, Prokaryotic Expression and Binding Characterization of Odorant Binding Protein GdauOBP20 in Galeruca daurica
    Ling LI,Yao TAN,XiaoRong ZHOU,BaoPing PANG
    Scientia Agricultura Sinica. 2019, 52(20):  3705-3712.  doi:10.3864/j.issn.0578-1752.2019.20.020
    Abstract ( 347 )   HTML ( 9 )   PDF (1588KB) ( 416 )   Save
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    【Objective】 Galeruca daurica is a new pest with outbreak status in the Inner Mongolia grasslands in recent years. The objective of this study is to clone the full-length cDNA sequence of GdauOBP20, and clarify the binding property of the recombinant protein to main host plant volatiles, which will lay a necessary foundation for revealing the molecular mechanism of olfaction in G. daurica.【Method】 RACE technique was used to clone the full-length cDNA of GdauOBP20 based on the transcriptome database of G. daurica. The physicochemical properties and structural characteristics of the encoded protein were predicted and analyzed by bioinformatics software. The recombinant protein GdauOBP20 was induced to express by constructing prokaryotic expression system, and purified by using the Ni-NTA Agarose affinity column. Finally, the fluorescence competitive assay was applied, and N-phenyl-1-naphthylamine (1-NPN) was selected as the fluorescence probe to measure the binding profiles of GdauOBP20 recombinant protein with 13 main host plant volatiles.【Result】 The full-length cDNA of GdauOBP20 is 567 bp (GenBank accession number: MK250532), with the non-coding regions of 5′ and 3′ ends of 24 bp and 123 bp, respectively, and a ployA tail structure. The open reading frame (ORF) is 420 bp, encoding 139 amino acids. The amino acid sequence of GdauOBP20 contains 4 conserved cysteine residues, indicating that it belongs to Minus-C OBP subfamily. The three-dimensional structure prediction of GdauOBP20 contains six alpha helix and two pairs of disulfide bonds formed by cysteine. The recombinant expression vector was successfully constructed, and the recombinant protein with high purity was obtained. The binding capacity of the recombinant protein GdauOBP20 to the fluorescence probe 1-NPN was strong with a binding constant of 12.8 μmol·L -1, indicating that it could be used as the fluorescence reporter in this experiment. Affinities of recombinant protein GdauOBP20 with 13 main host plant volatiles were tested. Among them, except diallyl trisulfide, other 12 volatiles showed certain binding capacities with the recombinant protein, and p-xylene and 1,3,5-cycloheptatriene displayed the strongest affinity with the dissociation constants of 22.91 and 26.55 μmol·L -1, respectively, whereas myrcene exhibited the weakest binding affinity with the dissociation constant of 116.29 μmol·L -1.【Conclusion】 GdauOBP20 has a certain binding capacity with main host plant volatiles, suggesting that it may play an important role in the localization of host plants.