Loading...

Table of Content

    16 December 2022, Volume 55 Issue 24
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Phenotypic Analysis and Gene Cloning of Rice Panicle Apical Abortion Mutant paa21
    HE Lei,LU Kai,ZHAO ChunFang,YAO Shu,ZHOU LiHui,ZHAO Ling,CHEN Tao,ZHU Zhen,ZHAO QingYong,LIANG WenHua,WANG CaiLin,ZHU Li,ZHANG YaDong
    Scientia Agricultura Sinica. 2022, 55(24):  4781-4792.  doi:10.3864/j.issn.0578-1752.2022.24.001
    Abstract ( 317 )   HTML ( 71 )   PDF (3347KB) ( 223 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】Rice panicle apical abortion affects yield. Identification and cloning of genes related to rice panicle apical abortion can enrich the molecular mechanism of rice panicle development regulation, and provide theoretical basis and genetic resources for rice high-yield molecular design breeding. 【Method】Here, a stably inherited panicle apical abortion 21 (paa21) mutant was screened from EMS mutant library of the japonica rice variety "Wuyunjing 30". Agronomic traits, such as ratio of degraded primary branches, degraded apical spikelets, grains per panicle, plant height, panicle length, and grain yield per plant, were statistically analyzed. Trypan blue and Evans blue staining were used to detect whether programmed cell death occurred in the apical spikelets. H2O2 content in young panicles at different development stages and different panicle parts of WT and paa21 was determined. Genetic analysis was carried out by reciprocal cross of paa21 with indica rice II-32B and 9311 respectively. The F2 population constructed by crossing paa21 with indica rice II-32B was used for gene mapping and cloning. The three-dimensional structure of wild-type and paa21 proteins were predicted using SWISS-MODEL website. The expression levels of ROS response marker genes, programmed cell death related genes and catalase related genes were analyzed by RT-qPCR. 【Result】paa21 produced panicle apical abortion phenotype and the degenerated spikelets were mainly located on the primary branches at the apical panicle. The plant height, grain number per panicle, panicle length and grain yield per plant of paa21 were lower than those of WT. After observing the young panicles at different development stages, we found that the paa21 mutant had a panicle apical abortion phenotype when panicle developed to 12 cm. Trypan blue and Evans blue staining results showed that the apical spikelets of the paa21 mutant had programmed cell death. Stronger DAB staining was observed in the degenerated apical spikelets of paa21 than WT. The results of H2O2 content determination showed that higher level of ROS was accumulated in panicle of paa21 compared with WT. Genetic analysis suggested that paa21 mutant phenotype is controlled by a pair of recessive nuclear genes. The results of map-based cloning showed that a C to T mutation occurred in the second exon of Os02g0673100 in paa21, resulting in the mutation of alanine to valine. This gene encodes an aluminum activated malate transporter, ALMT7. The mutation site was located at the fourth transmembrane helix. SWISS-MODEL prediction results showed that the mutation site did not significantly affect the three-dimensional structure of the mutant protein. The expression level of ROS response marker genes Os01g0826400, Os05g0474800 and Os02g0181300 in paa21 was significantly higher than that in WT when the young spike developed to 10 cm. Compared with WT, the expression level of programmed cell death related genes VPE2 and VPE3 increased significantly in paa21. The expression level of CATA, CATB and CATC which encode catalase in 10 cm young panicle of paa21 was significantly higher than that of WT. The activity of CAT in paa21 10 cm young spikelet was significantly lower than that of WT. 【Conclusion】paa21 accumulate excess ROS in the apical spikelet at late stage of panicle development, resulting in programmed cell death, which eventually leads to the degeneration of the apical spikelet. These results lay a good foundation for further enriching the genetic regulatory network of panicle development.

    Dynamic Changes of Gibberellin Content During the Development and Its Relationship with Yield of Brassica napus L.
    XIE LingLi,WEI DingYi,ZHANG ZiShuang,XU JinSong,ZHANG XueKun,XU BenBo
    Scientia Agricultura Sinica. 2022, 55(24):  4793-4807.  doi:10.3864/j.issn.0578-1752.2022.24.002
    Abstract ( 243 )   HTML ( 31 )   PDF (765KB) ( 121 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】It was found that there were significant genetic differences between Chinese and European Brassica napus lines, and the yield advantage of hybrid F1 was obvious. To explore the effect of gibberellin (GA) on the growth and development of B. napus, the dynamic changes of GA during the developmental process of B. napus from different lines were measured. For explaining the role of GA in the formation of yield, the transcriptional levels of key enzyme genes involved in GA synthesis were analyzed, and the relationship between GA content and yield in parents and F1 was clarified. 【Method】The dynamic changes of GA content in B. napus lines (15 Chinese lines and 15 European lines) with different sources from November 2020 to May 2021were determined using high performance liquid chromatography. Two F1hybrid lines (YG2009×YC4, ZS11×YC4) with strong heterosis and their parents were used as materials to investigate the changes of GA content in different periods (D1, 15 January 2022; D2, 15 February 2022; D3, 15 March 2022)and measure growth indicators (plant height, root length, fresh weight, etc.), yield and component factors (silique number per plant, seed number per silique and thousand-seed weight), as well as photosynthetic indicators (photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration).The change trend of GA content with temperature and the relationship between GA content and agronomic characters, photosynthetic characteristics and yield of parents and F1hybrid from November 2021 to May 2022 were analyzed. Besides, the transcriptional levels of key enzyme genes involved in GA synthesis of the parents and F1 at different stages (D1, D2, D3) also examined by quantitative real-time PCR. 【Result】The content of GA was closely related to the ambient temperature, and the GA content in the tested B. napus lines decreased first and then increased with the change of temperature. However, it was found that the average content of GA in B. napus lines from Europe was higher than that of Chinese lines. F1 showed significant yield heterosis. Compared with the male and female parents, the yield of YG2009×YC4 and ZS11×YC4 increased by 18.06% and 10.35%, and 29.92% and 28.6%, respectively. There were significant differences in agronomic traits between parents and F1, and the yield was correlated with GA content. The results also showed that the transcriptional levels of GA20ox4, GA3ox2 and SLR1 in parents and hybrid F1 varied greatly. 【Conclusion】The GA content of B. napus lines from Europe was more sensitive to temperature changes, but its average content of GA was higher than that from China. The yield of F1 between European rape and Chinese rape lines showed strong heterosis, which was correlated with GA content. The transcriptional levels of GA20ox4 and GA3ox2 regulated the GA content.

    TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY
    Effects of Ethylene-Chlormequat-Potassium on Root Morphological Construction and Yield of Summer Maize with Different Nitrogen Application Rates
    FANG MengYing, LU Lin, WANG QingYan, DONG XueRui, YAN Peng, DONG ZhiQiang
    Scientia Agricultura Sinica. 2022, 55(24):  4808-4822.  doi:10.3864/j.issn.0578-1752.2022.24.003
    Abstract ( 279 )   HTML ( 40 )   PDF (1735KB) ( 154 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】 Root is an important organ for maize to obtain water and nutrients, and a developed root structure is the key to maximum maize yield potential, which is currently an important issue to be solved in maize cultivation research. Ethylene- chlormequat-potassium and nitrogen application can affect the development of the maize root system. The aim of this study was clarify the effects of ethylene-chlormequat-potassium on the construction of summer maize root morphology and yield under different nitrogen application rates, so as to provide the theoretical and technical basis for the improvement of high yield and efficient cultivation management and rational fertilization of maize. 【Method】In 2019 and 2020, the field experiments were carried out in Daliudian village, Yanjiao town, Langfang city, Hebei province, and Shunyi Experimental Base, Chinese Academy of Agricultural Sciences, Shunyi district, Beijing, respectively, using maize single cross Yudan 9953 as experimental material. A split-zone experimental design was used, with the ethylene-chlormequat-potassium treatment (ECK) and the clear water control (CK) as the main zones, and the six nitrogen levels of 0 (N0), 96 (N96), 132 (N132), 168 (N168), 204 (N204) and 240 kg·hm-2 (N240) as the secondary zones, aiming to analyze the effects of ECK on root morphology and yield of summer maize at different nitrogen application rates. 【Result】The nitrogen application significantly increased root dry weight, number of aerial roots, root length, root surface area and root volume. Compared with no nitrogen application, root dry weight, the number of aerial roots, root length, root surface area and root volume increased by 15.0%-25.2%, 31.7%-71.7%, 15.5%-30.8%, 19.0%-40.9% and 28.8%-54.0% on average with different nitrogen application rates, respectively. Compared with CK, ECK treatment increased root dry weight, number of root layers, number of roots in 1 to 2 layers and the number of aerial roots in summer maize with different nitrogen application rates by 10.4%-17.0%, 5.8%-12.6%, 10.8%-33.9% and 12.5%-79.6%, respectively; On the construction of root morphology, compared with CK, ECK treatment significantly increased the total root length, root surface area and root volume of summer maize with different nitrogen application rates by 7.5%-21.0%, 8.4%-29.3% and 14.3%-38.8%, respectively, and the root length with root diameter > 1.0 mm was significantly increased at medium and high nitrogen levels (N≥N204). Compared with CK, ECK treatment had no significant effect on summer maize yield per unit area in 2019 and 2020 under N0-N168, but significantly increased summer maize yield in 2019 and 2020 under N204 and N240, which increased by an average of 6.3% with N204 and 3.2% with N240. Correlation analysis showed that kernel number, 1000-kernel weight, root length, root surface area and root volume were positively correlated with summer maize yield, and the correlation coefficient between yield and root length was the highest. 【Conclusion】ECK and nitrogen could synergistically promote maize root development and increase summer maize yield under high nitrogen conditions. In the current study, spraying ECK at the V6 growth stage combined with 204 kg·hm-2 N fertilizer was a suitable cultivation technique and N fertilizer management practice for high-yielding summer maize in the Beijing-Tianjin area.

    SPAD Value Inversion of Cotton Leaves Based on Satellite-UAV Spectral Fusion
    WANG ShuTing, KONG YuGuang, ZHANG Zan, CHEN HongYan, LIU Peng
    Scientia Agricultura Sinica. 2022, 55(24):  4823-4839.  doi:10.3864/j.issn.0578-1752.2022.24.004
    Abstract ( 224 )   HTML ( 25 )   PDF (3452KB) ( 107 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】The aim of this study was to improve the inversion accuracy of chlorophyll content in cotton leaves, and to grasp its spatial distribution characteristics in Xiajin county, Shandong province. 【Method】Taking Xiajin county, Dezhou city, Shandong province as the study area and Dalizhuang cotton field in Xiajin county as the test area, the relative value of chlorophyll content (SPAD value) in cotton leaves in the experimental area was measured by SPAD (soil and plant analyzer development), and obtained the near earth multispectral image of unmanned aerial vehicle (UAV) and Sentinel-2A MSI (MSI) satellite image in the study area in the same period; Then, based on the spectral reflectance of UAV and MSI satellite images, the optimal spectral parameters were constructed and selected, and the inversion model of SPAD value was established by multiple linear regression (MLR); Finally, the quadratic polynomial fitting method was used to fuse the optimal spectral parameters corresponding to UAV and Sentinel-2A MSI. By comparing and analyzing the model effects before and after fusion, the inversion model was optimized, and the SPAD value inversion of the study area was realized. 【Result】(REG-R)/(REG+R), R/G, Cl(red edge) and NDVI could be the optimal spectral parameters of SPAD value. The precision of cotton leaf SPAD inversion model based on UAV near ground image was better than that based on satellite image; After quadratic polynomial fitting, the calibration R2 was increased by 0.015-0.057, and RMSE was decreased by 0.457-0.638, while the validation R2 was increased by 0.040-0.085, RMSE was decreased by 0.387-0.397, and RPD was increased by 0.020-0.139. The fused spectral parameters based on Sentinel-2A MSI image were input to the inversion model based on UAV data (Fused MSI-ModUAV), the high inversion accuracy of SPAD value in cotton leaves could be obtained, with the model calibration R2 up to 0.672, RMSE of 3.982, validation R2 up to 0.713, RMSE of 3.859, and RPD of 1.685. Based on the above model, two inversion prediction maps of different scales were obtained. The SPAD value of cotton leaves in the test area showed the distribution trend of high in the south and low in the north, and the study area showed the distribution trend of low in the middle and high around, which were consistent with the field situation and showed the model had a good prediction effect. 【Conclusion】Therefore, the fusion of UAV and satellite image data by using quadratic polynomial fitting method could better realize the quantitative inversion of regional high-precision crop growth indicators. The research results could enrich the theory and technology of multi-source remote sensing fusion, and provide the technical reference and data support for cotton growth monitoring and precision production.

    PLANT PROTECTION
    Construction and Application of Infectious Clone of Citrus Yellow Mosaic Virus
    JIANG QiQi,XU JianJian,SU Yue,ZHANG Qi,CAO Peng,SONG ChenHu,LI ZhongAn,SONG Zhen
    Scientia Agricultura Sinica. 2022, 55(24):  4840-4850.  doi:10.3864/j.issn.0578-1752.2022.24.005
    Abstract ( 269 )   HTML ( 36 )   PDF (3944KB) ( 120 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】An infectious clone of citrus yellow mosaic virus (CYMV) was constructed to lay a foundation for further study of its molecular characteristics and pathogenic mechanism. 【Method】The amplified CYMV genomic sequence segments were recombined with the ternary expression vector pCY using In-Fusion homologous recombination technology, and a 1.4-fold full-length genomic DNA clone of the virus was constructed and sequenced. The obtained clones were inoculated onto seedlings of Eureka lemon by Agrobacterium-mediated vacuum infiltration (AVI), and their infectivity was identified by molecular detection, presentation of symptoms and virus particles, and re-grafting determination. The obtained infectious clones were used to inoculate different citrus varieties and herbs, and the infection rate was determined by RT-PCR and the various symptoms of different citrus varieties after infection were observed. Mutants of the infectious clones with ORFⅠand ORFⅡ replaced by green fluorescent protein gene (gfp), respectively were constructed, and subjected to infectivity analysis. 【Result】Seven clones of 1.4-fold CYMV genome-length DNA were obtained by In-Fusion homologous recombination technology. Among them, CYMV-3 was 90%-100% identical to the corresponding genomic nucleotide sequences of nine CYMV isolates registered in GenBank, and had the highest homology with CYMV-SO isolate (AF347695) and was clustered on the same branch of the genetic evolutionary tree. The results of infectivity identification showed that four out of the 14 Eureka lemon plants inoculated with CYMV-3 were positive by RT-PCR detection, and punctate chlorotic symptoms were observed. DNA was extracted from the new systemic leaves of the infected plant and the expected specific fragments covering the full length of the CYMV genome were obtained by PCR amplification. CYMV-3 infected plants with symptoms were used as the virus source to graft and inoculate rough lemon seedlings, and CYMV specific bands could be detected by RT-PCR at 90 dpi. New leaves of CYMV-3 infected plants with symptoms were taken for fixation and sectioning for electron microscopy and baculovirus particles of about 130 nm × 30 nm were observed, indicating that CYMV-3 was a CYMV infectious clone. Ten and five citrus varieties were inoculated by CYMV-3 via Agrobacterium-mediated vacuum infiltration and injection, respectively, and were tested by RT-PCR. The results showed that the infection rate of the former was 11.11%-100.00% and the latter was 63.16%-90.00%. Some citrus varieties appeared CYMV symptoms such as yellowing, mosaic and yellowing patches. Nicotiana benthamiana, Zea mays, Vigna unguiculata and Sorghum bicolor were inoculated by CYMV-3 via Agrobacterium -mediated injection, and only S. bicolor plants were detected to be positive in RT-PCR detection, and chlorotic strips appeared along the veins of the systemic leaves, indicating that CYMV can infect S. bicolor. The mutants of CYMV-3 with ORFⅠand ORFⅡ replaced by gfp, respectively, were constructed and inoculated onto rough lemons by Agrobacterium-mediated injection. All the inoculated plants were negative by RT-PCR detection and showed no obvious symptoms. 【Conclusion】The infectious clone of CYMV was successfully constructed and could infected citrus plants efficiently via Agrobacterium-mediated injection, resulting different symptoms in different varieties.

    Development and Application of ELISA Kit for Detection of EPSPS in Eleusine indica
    LI ZhiLing,LI XiangJu,CUI HaiLan,YU HaiYan,CHEN JingChao
    Scientia Agricultura Sinica. 2022, 55(24):  4851-4862.  doi:10.3864/j.issn.0578-1752.2022.24.006
    Abstract ( 177 )   HTML ( 24 )   PDF (870KB) ( 63 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】The objective of this study is to clone the target gene EPSPS of glyphosate in Eleusine indica, obtain the recombinant protein and antibody against EPSPS protein, then assemble the EPSPS ELSIA kit, finally, to detect the EPSPS expression and protein content of different plants and tissues of E. indica, and to provide a powerful tool for rapid identification of glyphosate resistant individuals. 【Method】The full-length of EPSPS was cloned by PCR method. The constructed pET30a-EPSPS positive plasmid was transformed into host bacteria BL21, which was induced by IPTG to express and purify the protein. Monoclonal and polyclonal antibodies were prepared by immunizing mice and New Zealand white rabbits with EPSPS recombinant protein as immunogen, and the specificity of the antibodies was detected by Western blot. Best matching antibody was screened by indirect ELISA. The working concentration of each reagent was optimized and the kit was assembled. The content of EPSPS in different E. indica populations was detected by the assembled kit and compared with the results of qPCR. 【Result】The open reading frame of EPSPS contains 1 620 bp nucleotide and encodes 540 amino acids, with a theoretical isoelectric point of 8.80. The protein has no transmembrane region. The evolutionary tree analysis showed that the evolutionary relationship between EPSPS of E. indica and EPSPS of rice was the closet. The protein could be expressed under a condition of 1 mmol·L-1 IPTG, 25℃. After purification, the purity of prokaryotic expression protein was more than 90%, the concentration was 3 mg·mL-1, and the protein content was 12 mg. Polyclonal antibodies produced from rabbits numbered R1711 and R1712 showed higher potency. Monoclonal antibodies produced from mice numbered M171070, M171071 and M171072 showed higher potency. A group of optimal matching antibodies (FL-374-08 monoclonal antibody and polyclonal antibody) were screened. The optimal concentration of coated antibody was 2 μg·mL-1. The optimal concentration of enzyme-labeled antibody was 10 μg·mL-1. The linear detection range of ELISA kit was 5-80 μg·kg-1, and the detection limit was 5 μg·kg-1. The expression of EPSPS in leaf of resistant individuals was 52.9 times higher than that in the susceptible individuals. Similarly, it was 63.0 times higher in stem. In the resistance individuals, the relative copy number of EPSPS in leaf was 53.5 times higher than that in the susceptible individuals, and it was 78.6 times higher in stem. Western blot results showed that monoclonal antibodies had specific immunity to EPSPS and could accurately distinguish the difference of protein content in different plants and tissues. The concentration of EPSPS in stem of resistant individuals was 6.0 μg·L-1, while, it was only 0.22-0.43 μg·L-1 in susceptible individuals, which detected by ELISA kit. 【Conclusion】The monoclonal antibody of EPSPS obtained in this study showed higher specificity, and sensitivity. The ELISA kit can be used to quickly and accurately identify glyphosate resistance in E. indica which caused by EPSPS overexpression.

    SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT
    Effects of Reducing Nitrogen Application Rate on the Yields of Three Major Cereals in China
    DU WenTing,LEI XiaoXiao,LU HuiYu,WANG YunFeng,XU JiaXing,LUO CaiXia,ZHANG ShuLan
    Scientia Agricultura Sinica. 2022, 55(24):  4863-4878.  doi:10.3864/j.issn.0578-1752.2022.24.007
    Abstract ( 410 )   HTML ( 48 )   PDF (624KB) ( 269 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】 The present study investigated the effects of reducing nitrogen application rate on the yields of three major cereals in China and its relationship with soil and other factors, so as to clarify the feasibility of reducing nitrogen application. 【Method】 90 published papers from 2010 to 2021 were collected and analyzed the effects of different nitrogen fertilizer reduction ratios on yield, and its relationship with planting systems and different conditions (fertilizer type, soil organic matter content, total nitrogen, soil pH, and water management). 【Result】 Compared with conventional fertilization rate, 0-40% nitrogen reduction did not significantly reduce the yield of rice, 0-30% nitrogen reduction did not significantly affect the yields of wheat and maize, when the nitrogen reduction was 30%-40%, the yield of wheat and maize significantly reduced by 6.1% and 5.4%, respectively. The yield level without nitrogen input area did not significantly affect crop yield of the three cereals following reduction of nitrogen rate. When soil total nitrogen was more than 2 g·kg-1, rice yield with reduced nitrogen application (6.5 t·hm-2) was significantly higher than that with conventional nitrogen application (6.3 t·hm-2); when total nitrogen was more than 1 g·kg-1, wheat yield with reduced nitrogen application (6.9 t·hm-2) was significantly lower than that with conventional nitrogen application (7.4 t·hm-2); when total nitrogen was more than 1.5 g·kg-1, maize yield with reduced nitrogen application (8.8 t·hm-2) was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). When soil organic matter content was more than 30 g·kg-1, rice yield with reduced nitrogen application (6.9 t·hm-2) was significantly higher than that with conventional nitrogen application (6.7 t·hm-2), but soil organic matter content were 10-20 g·kg-1 and more than 20 g·kg-1, the reducing nitrogen application significantly reduced wheat yield. When soil pH was lower than 6.5, rice yield with reduced nitrogen application (6.6 t·hm-2) was significantly higher than that with conventional nitrogen application (6.4 t·hm-2). Wheat yield (6.6 t·hm-2) with reducing nitrogen application under single cropping was significantly higher than that with conventional nitrogen application (5.9 t·hm-2); maize yield (8.9 t·hm-2) with reducing nitrogen application under double cropping was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). Based on common fertilizer, wheat yield with reducing nitrogen application (6.8 t·hm-2) was significantly lower than that with conventional nitrogen application (7.1 t·hm-2). Under rainfed, wheat yield with reducing nitrogen application (5.9 t·hm-2) was significantly lower than that with conventional nitrogen application (6.6 t·hm-2). 【Conclusion】 The yield of three major cereals in China can be maintained by reducing conventional nitrogen application rate by 30% although crop yield varied to certain extent with soil properties and management measures. Therefore, the reduced application of nitrogen fertilizer needed to be adjusted according to soil properties and management practices to achieve high yield and high nitrogen efficiency.

    Provincial Agricultural Ecological Efficiency and Its Influencing Factors in China from the Perspective of Grey Water Footprint
    DENG YuanJian,CHAO Bo
    Scientia Agricultura Sinica. 2022, 55(24):  4879-4894.  doi:10.3864/j.issn.0578-1752.2022.24.008
    Abstract ( 424 )   HTML ( 40 )   PDF (617KB) ( 85 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】This paper evaluated Chinese provincial agricultural ecological efficiency from the perspective of gray water footprint, revealed the spatial distribution characteristics of agricultural ecological efficiency, analyzed the main factors affecting agricultural ecological efficiency, and put forward policy suggestions to improve Chinese provincial agricultural ecological efficiency. 【Method】Based on the provincial panel data of China from 2000 to 2019, this paper comprehensively evaluated the agricultural ecological efficiency of Chinese provinces with the super efficiency SBM model considering the unexpected output, and used the spatial Dobbin model to analyze the spatial differences and influencing factors of agricultural ecological efficiency. 【Result】(1) In general, the agricultural grey water footprint showed a downward trend, but in some provinces (cities and districts), it showed an upward trend. From the ranking of grey water footprint from low to high, it could be seen that the provinces (cities and districts) in the forefront (i.e. with less grey water footprint) had a high level of economic development or a relatively low proportion of agricultural output value; the provinces (cities and districts) in the rear row (i.e. with more grey water footprint) had low economic development level or high agricultural output value. (2) During the observation period, the agricultural ecological efficiency fluctuated greatly in some years in the stable trend, and the average difference among provinces (cities and districts) was obvious and the distribution was extremely unbalanced. (3) Economic development level, fiscal expenditure for supporting agriculture, technological progress, agricultural disaster rate, planting structure and other factors had different impacts on Chinese agricultural ecological efficiency. With the improvement of both economic development level and people's living quality, both agricultural operators and consumers paid more attention to the protection of agricultural ecological environment and the quality of agricultural products, which have improved the level of regional agricultural ecological efficiency to a certain extent. But the pollution caused by regional economic and social development might also have a negative impact on agricultural ecological efficiency. Most of the financial support for agriculture was used to subsidize production links, such as pesticides, chemical fertilizers, and agricultural machinery. Although the agricultural production conditions have been improved and the agricultural economic productivity and efficiency have been improved, the improvement of agricultural ecological efficiency was not significant. The development of technology was very important in the agricultural production process, and the proper use of it would improve the agricultural ecological efficiency. The estimated results of agricultural disaster rate failed to pass the significance test, which might be because the expansion of agricultural disaster area would lead to the decline of agricultural ecological efficiency, but the annual disaster situation was not regular. The coefficient of planting structure was negative, which had a negative impact on agricultural production efficiency. This might be due to the high proportion of grain crop planting area in the total planting area of crops, and the high consumption of nitrogen fertilizer. 【Conclusion】As the evolution trend and difference of agricultural gray water footprint in various provinces (cities and districts) in China were obvious, the overall level of agricultural ecological efficiency was not high, and various factors have different impacts on agricultural ecological efficiency, it was necessary to improve the governance mechanism of agricultural gray water footprint; optimize the agricultural industrial structure and establish a compensation mechanism for agricultural water resources protection based on gray water footprint; improve the ways and policies of financial support for agriculture, and guide business entities to actively improve agricultural ecological efficiency.

    HORTICULTURE
    Genome-Wide Identification of NAC Family and Screening of Its Members Related to Prickle Development in Rosa chinensis Old Blush
    YOU YuWan,ZHANG Yu,SUN JiaYi,ZHANG Wei
    Scientia Agricultura Sinica. 2022, 55(24):  4895-4911.  doi:10.3864/j.issn.0578-1752.2022.24.009
    Abstract ( 281 )   HTML ( 38 )   PDF (5135KB) ( 123 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】This study was designed to identify the NAC gene family in Rosa chinensis Old Blush and to analyze the sequences characteristics and expression pattern of RcNACs to reveal the biological functions of RcNACs, which also provided an important foundation to explore the role of RcNACs in prickles. 【Method】The BLATP and HMMER search were conducted to identify NAC proteins in Rosa chinensis Old Blush using the sequences of NAC proteins of Arabidopsis. Physical and chemical properties, subcellular location, structure and phylogenetic relationship of each gene were further analyzed. Based on the released transcriptome data, the expression characteristics of RcNACs in different tissues and organs under different stress conditions were analyzed. What’s more, the technology of RNA-seq was used to screen RcNAC genes that might be related to the prickle development. 【Result】In this study, 116 NAC genes from Rosa chinensis Old Blush genome were identified and characterized. These RcNACs genes encoded proteins containing 69 to 713 amino acids, with the theoretical isoelectric points ranging from 4.43 to 9.54 and the molecular weight ranging from 7.87 to 79.99 kD. The prediction of subcellular localization showed that 81 RcNACs were located in the nucleus. Moreover, RcNACs were unevenly distributed on 7 chromosomes. According to phylogenetic relationships, AtNACs, OsNACs and RcNACs were clustered into 21 groups. These 116 RcNACs were differentially expressed in various tissues and organs, and the expression levels of 31 members changed in response to abiotic and biotic stresses. Furthermore, in the RNA-seq data of prickles, 53 RcNACs were detected, among which 26 members were differentially expressed genes. 【Conclusion】This study demonstrated that RcNACs were involved in the regulation of plant development and stress responses. Some members might be involved in the processes of prickle cell proliferation, secondary cell wall biosynthesis, and programmed cell death, which could be selected as candidate genes related with prickle development for further study.

    Cloning and Interaction Protein Screening of RHF2A Gene from Xiangshui Lemon
    LI YuZe,ZHU JiaWei,LIN Wei,LAN MoYing,XIA LiMing,ZHANG YiLi,LUO Cong,HUANG Gui Xiang,HE XinHua
    Scientia Agricultura Sinica. 2022, 55(24):  4912-4926.  doi:10.3864/j.issn.0578-1752.2022.24.010
    Abstract ( 222 )   HTML ( 33 )   PDF (3123KB) ( 105 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】Xiangshui lemon (Citrus limon (L.) Burm. F.) was used to study the expression of two RHF2A genes, and to screen and verify their interaction proteins by yeast two-hybrid technology and BiFC, so as to lay a foundation for further studying the molecular mechanism of RHF2A in the process of lemon self-incompatibility. 【Method】Two E3 ubiquitin ligase RHF2A (RING-H2 Zinc Finger2A) genes including RHF2A-1 and RHF2A-2 of Xiangshui lemon were screened from the transcriptome and ubiquitin modification group, and their full-length sequences were cloned. The sequence and protein structure of two RHF2A genes were analyzed by bioinformatics to predict the cis acting elements of their promoters. 35S-RHF2A-GFP fusion protein expression vector was constructed for subcellular localization analysis. The temporal and spatial expression patterns of two RHF2A were analyzed by real-time fluorescence quantitative PCR. The yeast two-hybrid bait vector was constructed to screen the interaction proteins from the lemon yeast library. The BiFC vector was constructed to verify the interaction of the target protein in onion living cells. 【Result】The RHF2A-1 and RHF2A-2 genes were obtained from ‘Xiangshui’ lemon, and the total length of ORF was 1 161 and 1 134 bp, respectively. NCBI domain prediction found that it had a Ring/U-box domain. Promoter analysis showed that there were POLLEN1LELAT52 and GTGANTG10 related to pollen specific expression elements. Tissue expression analysis showed that RHF2A-1 gene was specifically expressed in pollen and RHF2A-2 was specifically expressed in leaves; the results of temporal and spatial expression analysis showed that the expressed of RHF2A-1 in self-stigma tended to increase from the first day and reached the peak on the third day, which was more than 5 times that of hybrid stigma. Subcellular localization showed that RHF2A-1and RHF2A-2 were localized in the nucleus. The interaction protein predicted by Uniprot website showed that RHF2A could interact with KRP6, AT3G57370, UBA1, FBL17 and SK11proteins, and RHF2A gene was involved in biological processes such as self-incompatibility ubiquitination reaction pathway, gametophyte development regulation and pollen growth and development. 72 clones were screened by yeast two-hybrid technology. After sequencing and blast comparison, the repetitive clones were excluded. Finally, 20 candidate interaction proteins such as ABCF3 were obtained. Through one-to-one interaction verification and BiFC, it was determined that there was an interaction relationship between RHF2A-1 and ABCF3-2. 【Conclusion】The temporal and spatial expression of RHF2A-1 gene was consistent with the germination of pollen on pistil in the process of self-incompatibility; the interaction candidate proteins directly affecting pollen growth and development during the pollination were screened, which preliminarily proved that RHF2A-1 gene played an important role in the process of self-incompatibility.

    FOOD SCIENCE AND ENGINEERING
    Optimization of Drying Process in Oat Noodle Production
    LIU ZhenRong,ZHAO WuQi,HU XinZhong,HE LiuCheng,CHEN YueYuan
    Scientia Agricultura Sinica. 2022, 55(24):  4927-4942.  doi:10.3864/j.issn.0578-1752.2022.24.011
    Abstract ( 208 )   HTML ( 42 )   PDF (2014KB) ( 66 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】 The effects of different drying modes, temperature, and relative humidity on drying quality and drying energy of oat noodles were studied. The modes were established and the multi-objective optimization was carried out to obtain the drying mode and process parameters of oat noodles with good quality and low energy consumption. 【Method】The effects of nine different drying modes of temperature and humidity on the drying quality and drying energy of oat noodles were studied. The factors of optimal cooking time, cooking loss, water absorption, ductility, hardness, chewiness, adhesiveness, bending strength, breaking distance, acidity and fatty acid value were analyzed to obtain the comprehensive evaluation value of quality and determine the optimal drying mode of oat noodle. Plackett-Burman test was used to screen the first temperature, the first relative humidity, the second temperature, the second relative humidity, the third temperature and the third relative humidity of the three-stage drying of oat noodles with variable temperature and humidity. Box-Behnken response surface test was used to optimize the drying process, and the optimal parameters were obtained and verified. 【Result】The best drying mode of oat noodles was first heating and then cooling combined with dehumidification. Plackett-Burman experiment showed that the key factors of drying oat noodles were the first stage relative humidity, the second stage temperature and the second stage relative humidity. The established regression model of oat noodle drying process parameters with unit energy consumption and the comprehensive score was significant (P<0.05). Each factor had extremely significant influence on unit energy consumption. The interaction between the first relative humidity, the second temperature, and the second relative humidity was extremely significant. All factors had a significant influence on the quality comprehensive score, and the order of influence was second-stage temperature>second-stage relative humidity>first relative humidity. The interaction between first relative humidity, first relative humidity and second relative humidity was significant. The optimal process parameters for three-stage variable temperature and humidity drying of oat noodles were first stage temperature of 25℃, first stage relative humidity of 88%, second stage temperature of 43℃, second stage relative humidity of 71%, third stage temperature of 35℃, and third stage relative humidity of 50%; under this condition, the drying energy of oat noodles was 93.42 kJ·g-1, and the comprehensive score was 1.02. 【Conclusion】The established quadratic polynomial regression model could be applied to analyze and predict the effects of drying process parameters on drying energy and the comprehensive score of oat noodles. Three-stage variable temperature and humidity drying could improve the drying quality of oat noodles and reduce energy consumption. The method of using experiment design and data processing technology to solve the drying process of oat noodles was comprehensive and efficient. The results were intuitive and accurate, and the experiment efficiency and accuracy were improved. This study provided a theoretical basis for industrial standard production, energy-saving, and consumption reduction of oat noodles.

    ANIMAL SCIENCE·VETERINARY SCIENCE
    Effect of Litter Bed on Growth Performance and Odor Emission in Fattening Lamb
    CHE DaLu,ZHAO LiChen,CHENG SuCai,LIU AiYu,LI XiaoYu,ZHAO ShouPei,WANG JianCheng,WANG Yuan,GAO YuHong,SUN XinSheng
    Scientia Agricultura Sinica. 2022, 55(24):  4943-4956.  doi:10.3864/j.issn.0578-1752.2022.24.012
    Abstract ( 180 )   HTML ( 23 )   PDF (802KB) ( 57 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】 In view of the problem of odor non-point source pollution in fattening area of mutton sheep in recent years, the effects of bedding bed on growth performance of fattening lambs and odor components in the house were discussed, so as to provide technical path for odor emission reduction in fattening sheep house. 【Method】Two-hundred fifty healthy fattening lambs with similar weight and age were used and randomly divided into 5 groups according to different bedding materials, which were control group (plain soil), group A (full-sawdust), group B (furfural + sawdust), group C (rice husk + sawdust), and group D (corn cob + sawdust). The trial period was 90 days (d 1-45 in early period; d 46-90 in late period). The odor components in environment above and inside the litter bed were detected by using GC-MS method during different periods, and the effect of litter bed on production performance in fattening lambs was also analyzed. 【Result】(1) Compared with the control group, the four groups with litter bed demonstrated an increase in daily feed intake (P<0.05), which was increased by 7.7 % in group A and 8.7 % in Group B, 12.1 % in Group C, and 7.8 % in Group D. However, the daily gain and ratio of feed to gain exhibited no difference (P>0.05). (2) Nine kinds and eight kinds of odor components were detected throughout test period above litter bed and inside litter bed, respectively, and the components consisted of 31 kinds of volatile organic compounds (VOCs), including 4 alcohols, 10 alkanes, 3 amines, 1 phenol, 7 esters, 4 ketones, 2 aldehydes, 3 acids, and 1 thiol. The odor kinds detected in 4 litter groups were basically same as the control group. (3) From content analysis of odor components, the alkane content was the highest with 52.0 %-77.5 % among all odor components, no matter experimental period or detected space; however, no difference was observed among all groups (P>0.05). Also, the content of phenol or amine in litter groups demonstrated a decrease (P<0.05) in two detected spaces in early and late periods, compared with the control, exhibiting the decrease in group C was obvious. Besides, the content of alcohol, amine, or phenol was higher (P<0.05) in early period than that in late period both upper and inner spaces of litter bed; however, the ester content in late period was higher (P<0.05) than that in early period. (4) During entire experimental period, four kinds of key odor-causing substances were detected both in upper and inner of litter bed, including 2-ethylhexanol, N,N-dimethylacetamide, phenol, and 1 H-indole-3-thiol. For the contents of the four odor-causing components, each litter group showed a decreasing trend, compared with the control group, and the decrease in group C was the most obvious (P<0.05). 【Conclusion】In summary, four combined litter beds in this study could improve growth performance in fattening lambs, and decrease odor content in environment. The results would provide a technical pathway for reduction of odor emission in sheep barn.

    Comparison of Shell Mechanical Property, Ultrastructure and Component Between Chicken and Duck Eggs
    ZHANG YaNan,JIN YongYan,ZHUANG ZhiWei,WANG Shuang,XIA WeiGuang,RUAN Dong,CHEN Wei,ZHENG ChunTian
    Scientia Agricultura Sinica. 2022, 55(24):  4957-4968.  doi:10.3864/j.issn.0578-1752.2022.24.013
    Abstract ( 349 )   HTML ( 40 )   PDF (3716KB) ( 143 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】The research was conducted to study the comparison of shell mechanical property, ultrastructure and component between chicken and duck eggs. 【Method】160 eggs at the average weight from laying hens (Hy-Line grey) or ducks (Longyan Shanma) in aged 45 weeks were randomly divided into 2 groups, respectively. Each group had 20 eggs with 8 replicates. The laying hens and ducks were fed with maize-soybean meal basal diet, and the nutritional levels were formulated according to the national standard. The eggshell strength was measured by eggshell strength analyzer, the thickness of eggshell membrane and calcified eggshell was measured by digital micrometer, and then the eggshell ratio and toughness were calculated. Scanning electron microscope (SEM) was used to observe the ultrastructure of eggshell and to measure the effective thickness, mammillary thickness and width, and then to calculate the total thickness, the ratio of effective or mammillary thickness relative to total thickness. The mammillary structure was also observed by SEM and the degree of variation was scored. After crushing and extracting the eggshell, the content of matrix protein was determined by Coomassie brilliant blue method. After microwave digestion, the content of calcium, phosphorus, magnesium, manganese, copper and zinc in eggshell were determined according to the national standard method. 【Result】In comparison with chicken eggshell, the weight of duck egg and eggshell were increased (P<0.01), but the shell ratio was not changed (P>0.05); the eggshell breaking strength, toughness and eggshell membrane thickness were increased (P<0.01), but the thickness of the calcified eggshell (without shell membrane) was not changed (P>0.05). In respect to the ultrastructure, the thickness of mammillary layer and the number of mammillary knobs in per unit were decreased, but the mammillary knob width and mammillary layer ratio in duck eggshell were increased in relative to those of chicken eggs (P<0.001). No differences were observed in total and effective thickness (P>0.05), but the ratio of effective layer relative to total thickness was increased in duck eggshell (P<0.001). About the ultrastructure of mammillary knobs, there were no significant differences in the mammillae density, type B, type A, aragonite, cuff and pitted structure scores of the duck eggshell (P>0.05), the scores of the variations such as caps, early fusion and late fusion, and the total score of knobs were decreased in duck eggshell compared with chicken eggshell (P<0.05). There was higher frequency of mammillary structure variation in the chicken eggshell than the duck eggshell. The groove-like traces on the cap structure of the duck eggshell were deeper and clearer, the early fusion was more extensive, and the bonding between the knobs and the shell membrane fibers were denser than that in chicken eggshell. The contents of phosphorus, copper and manganese in duck eggshell were increased (P < 0.05), but the magnesium and matrix protein contents were decreased in duck eggshells relative to those in chicken eggshell (P<0.001), and there were no significant differences in calcium and zinc content (P>0.05). 【Conclusion】Above all, the eggshell quality of chicken and duck eggs were similar, and there were no differences in eggshell ratio, thickness of calcified layer, calcium and zinc content in eggshells. Compared with the chicken eggshell, the mechanical properties of duck eggshell were better, for shell breaking strength and toughness of duck eggshell were increased, which mainly due to the improvement of shell ultrastructure by increasing effective thickness and the ameliorate of mammillary knobs in duck eggshell. In addition, the phosphorus, copper and manganese content in duck eggshell were increased, but the content of magnesium and matrix proteins were decreased. In some content, the quality of duck eggshell could be improved by regulating the mineral elements and matrix protein content in eggshell, and modulated the process of eggshell formation, especially the deposition of calcium carbonate in the mammillary and palisade layers, and increased effective thickness and improved structure of the mammillary layer.

    RESEARCH NOTES
    Effects of Chilling on Chlorophyll Fluorescence Imaging Characteristics of Leaves with Different Leaf Ages in Tomato Seedlings
    HU XueHua,LIU NingNing,TAO HuiMin,PENG KeJia,XIA Xiaojian,HU WenHai
    Scientia Agricultura Sinica. 2022, 55(24):  4969-4980.  doi:10.3864/j.issn.0578-1752.2022.24.014
    Abstract ( 345 )   HTML ( 40 )   PDF (1347KB) ( 154 )   Save
    Figures and Tables | References | Related Articles | Metrics

    【Objective】This study analyzed the characteristics of chlorophyll fluorescence imaging of the 2nd (mature) and 4th (newly born) leaves of tomato seedlings in response to chilling stress, aiming to probe the mechanism of leaves with different ages adapted to chilling stress in tomato seedlings. 【Method】In this study, Solanum lycopersicum L. cv Zhongshu No. 4 was used as the research material. The tomato seedlings in the 4-leaf stage were treated at chilling (8℃, 200 μmol·m-2·s-1) for 15 d and then recovered at normal temperature (26℃ day/20℃ night, 500 μmol·m-2·s-1) for 1 d. The Chlorophyll fluorescence imagings of the whole seedlings were measured at different stages under different treatments, and the characteristics of chlorophyll fluorescence imaging of the 2nd and 4th leaves were compared. 【Result】The results showed that the relative area of photosynthetically active regions (RAP) on the 4th leaves decreased slowly during the first 5 d of the chilling stress, while the RAP on the 2nd leaves and the whole plants decreased steadily during the whole chilling treatment. The RAP recovered completely after 1 d of recovery. Under chilling treatment, the relative area of fluorescence active regions (RAF) for quantum yield of regulatory energy dissipation (Y(NPQ)), quantum yield of nonregulatory energy dissipation (Y(NO)), and nonphotochemical quenching (NPQ) showed similar changes as that of RAP. However, the RAF of effective PSII quantum yield (Y(II)) and coefficient of photochemical quenching (qP) were significantly lower than that of RAP. The maximum PSII quantum yield (Fv/Fm), Y(NPQ), and NPQ decreased while Y(NO) increased sharply in the photosynthetically active region in tomato seedlings during the first 5 d of the chilling treatment. In the following days, the Fv/Fm remained unchanged, whereas Y(NPQ) and NPQ increased and Y(NO) decreased. However, Y(II) declined sharply 1 d after chilling stress and then remained unchanged. Interestingly, qP in the photosynthetic active region of the 4th leaves decreased only slightly after 1 d of chilling treatment, and then maintained higher than that before treatment. However, qP of the 2nd leaves increased significantly on the 5th day and then decreased rapidly. Overall, the Fv/Fm, Y(II), Y(NPQ) and qP in the 4th leaves were higher than those in the 2nd leaves, whereas the Y(NO) were relatively lower in the 4th leaves. 【Conclusion】The study found that tomato seedlings responded to chilling stress by decreasing the area of photosynthetically active regions. The regulatory nonphotochemical quenching, which played a central role in photoprotection, was inhibited in the early stage, but gradually increased during the later stage under chilling treatment. The mature leaves adapted to chilling stress likely by decreasing the size of photosynthetically active regions, while higher capacities of PSII photochemistry and thermal dissipation were maintained in the newly born leaves in response to chilling stress. The protection of shoot apex and newly born leaves might be the priority of tomato seedlings in response to chilling stress. For newly born leaves, the chilling induced the closure of some active PSII reaction centers, but improved the operating efficiency of the remaining active PSII reaction centers, which was potentially beneficial for the recovery of photosynthetic activity.