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Table of Content

    12 June 2019, Volume 45 Issue 6
    • CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
      Fine mapping and candidate gene analysis of awn inhibiting gene B2 in common wheat
      Di JIN,Dong-Zhi WANG,Huan-Xue WANG,Run-Zhi LI,Shu-Lin CHEN,Wen-Long YANG,Ai-Min ZHANG,Dong-Cheng LIU,Ke-Hui ZHAN
      Acta Agronomica Sinica. 2019, 45(6):  807-817.  doi:10.3724/SP.J.1006.2019.81090
      Abstract ( 728 )   HTML ( 68 )   PDF (6260KB) ( 483 )   Save
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      Awn is one of the important photosynthetic organs in common wheat and plays a vital role in yield potential and environmental adaptation. At present, the inheritance and development of wheat awn have been not systematically studied, and cloning or fine mapping of related genes are seldom reported. In this study, the genetics and candidate genes conferring the short awn of a Chinese wheat landrace ‘Liuzhutou’ were investigated. Longitudinal section of awn showed cell size of short awn was much shorter than that of long awn. Using Wheat660K SNP chip based bulked segregant analysis (BSA) and SL-F2 population derived from ‘Liuzhutou’ (short awn) and modern cultivar ‘Shiai 1’ (long awn), the awn inhibiting gene in ‘Liuzhutou’ was mapped in a 4.84 Mb interval on chromosome 6BL and predicted as previously characterized B2. A good micro-collinearity of B2 region was observed among chromosomes 6B, 6A, 6D of Chinese Spring and chromosome 6B of AK58, there were 61 genes annotated in the 4.84 Mb B2 region, five of which were specifically expressed in the developing spike of Chinese Spring, and TraesCS6B02G264400 was differentially expressed between Chinese Spring and Azhurnaya. These data provide important clues for cloning the B2 gene, dissecting the developing mechanism of wheat awn and its application in molecular breeding.

      Detection of stem height QTL and integration of the loci for plant height- related traits in B. napus
      Li-Juan WEI,Rui-Ying LIU,Li ZHANG,Zhi-You CHEN,Hong YANG,Qiang HUO,Jia-Na LI
      Acta Agronomica Sinica. 2019, 45(6):  818-828.  doi:10.3724/SP.J.1006.2019.84133
      Abstract ( 499 )   HTML ( 13 )   PDF (1522KB) ( 228 )   Save
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      Stem height (SH) is important for the plant architecture and yield in Brassica napus. To date, the research about stem height in B. napus is very less. In the study, QTL mapping of stem height in B. napus was performed using the high density SNP genetic map constructed from the recombinant inbred lines (RIL) population with Illumina 60K SNP array. Totally 11 QTLs were detected in two years on A04, A06, C04, A08, and C01, which explained 7.25%-19.61% of the phenotypic variation. In addition, genome-wide association analysis (GWAS) of stem height in the 455 B. napus genotyped by resequencing was performed, and five significantly associated SNP loci on A08, A10, C02, and C06 were identified. And the candidate genes involved in photomorphogenesis, plant growth and development, and hormone pathway such as auxin, gibberellin and brassinosteroid were identified. We also integrated the loci for plant height-related traits including plant height (PH), main inflorescence length (MIL), branch segment (BS) and branch initiation height (BIH) in B. napus, in which four loci for PH on A01, A03, A07, C03, and C06 were identified in at least four populations, one locus for MIL on A10 and two loci for BIH on A02 and C03 were identified in two populations. The loci for stem height in our study were consistent with pervious QTL mapping results for plant height, branch initiation height and main inflorescence length. This study lays a foundation for the breeding of plant architecture in B. napus.

      Mapping of genes confessing same height of tiller and main stem in sorghum
      Rui WANG,Liang LING,Peng-Jie ZHAN,Ji-Zhen YU,Jian-Qiang CHU,Jun-Ai PING,Fu-Yao ZHANG
      Acta Agronomica Sinica. 2019, 45(6):  829-838.  doi:10.3724/SP.J.1006.2019.84111
      Abstract ( 625 )   HTML ( 5 )   PDF (6489KB) ( 359 )   Save
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      In this study, an F2 population derived from a cross between two sorghum lines with same height and different heights of tiller and main stem respectively was used to construct pools. In order to map genes related to same height of tiller and main stem, BSA and SLAF-seq technique were developed. Genetic analysis showed that the trait of same height of tiller and main stem was controlled by a single recessive nuclear gene. Reference genome of sorghum was used to design markers by simulating the number of markers produced by different enzymes. The SLAF library was conducted and sequenced by paired-end sequencing. The restriction enzyme was Rsa I + Hae III. The fragment length was 364-414 bp. The quality of Q30 was up to 91.70% and the GC content (45.79%) was low enough to perform sequencing. Compared with the sequencing data of rice, the construction of SLAF library fitted well to the standard, with its paired-end mapped reads reaching to 93.35% and normal digestion ratio reaching to 90.60% in sorghum. In total of 30.80 M reads and 133,246 SLAF labels were obtained and 319,428 SNPs were found. The associated region was located by SNP-index, Euclidean distance, and their combination. The candidate regions had a size of 1.95 Mb at nucleotides 54,788,026-56,740,873 on Chr.9. The SNPs locating at the associated region were analyzed between the two parents. Four non-synonymous-coding SNPs were found in this region. By verification, these SNPs were considered to be related to same height of tiller and main stem. Corresponding to three candidate genes (Sobic.009G197901.1, Sobic.009G213300.1, and Sobic.009G221200.1), these genes may be functional genes directly related to the traits.

      Creation of high oleic acid soybean mutation plants by CRISPR/Cas9
      Zhi-Hong HOU,Yan WU,Qun CHENG,Li-Dong DONG,Si-Jia LU,Hai-Yang NAN,Zhuo-Ran GAN,Bao-Hui LIU
      Acta Agronomica Sinica. 2019, 45(6):  839-847.  doi:10.3724/SP.J.1006.2019.84157
      Abstract ( 715 )   HTML ( 13 )   PDF (3352KB) ( 319 )   Save
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      Oleic acid content is one of the essential indicators to evaluate quality of oil in soybean. Three sites of 20 nt guide RNA (gRNA) targeted to the exon of GmFAD2-1A were designed and transcribed from the AtU3d, AtU3b, and AtU6-1 promoters, respectively. The three target sites of gRNA were ligated to the vector pYLCRISPR/Cas9-DB, and then the recombinant plasmid was transformed into a soybean cultivar Huaxia 3 by Agrobacterium-mediated transformation. The sequences near the editing site were analyzed by the PCR method and sequencing from T1 transgenic soybean plants, homozygous GmFAD2-1A mutants were obtained using CRISPR/Cas9 technology. The agronomic traits such as plant height, main stem number, branching number per plant, leaf shape, flower color, seed coat color, hilum color and growth period were no significant difference between the transgenic soybeans and non-transformed controls. However, the content of oleic acid in the transgenic soybean seed was significantly higher than that of the control cultivar Huaxia 3, indicating that GmFAD2-1A was a key gene during synthesis of oleic acid. We succeeded in editing the GmFAD2-1A by CRISPR/Cas9 technology in soybean and obtained homozygous mutant materials, which provides new germplasm resources and method for the breeding of high oleic acid.

      Establishment of a CRISPR/Cas9-VQR gene editing system
      Kai CHEN,Guo-Liang SUN,Gao-Yuan SONG,Ai-Li LI,Chuan-Xiao XIE,Long MAO,Shuai-Feng GENG
      Acta Agronomica Sinica. 2019, 45(6):  848-855.  doi:10.3724/SP.J.1006.2019.82052
      Abstract ( 584 )   HTML ( 10 )   PDF (949KB) ( 406 )   Save
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      Clustered Regularly Interspaced Short Palindromic Repeat and Cas9 (CRISPR/Cas9), a new generation of genome- editing technology, is widely applied among bacteria, yeast, animals and plants, however, the typical CRISRP/Cas9 cannot recognize the NGA proto-spacer-motif (PAM), which limits its application. In order to broaden the applications of CRIPSR/Cas9 system, we modified the Streptococcus pyogenes Cas9 (SpCas9) sequence by the PCR site-direct mutagenesis, which encodes V (1135), Q (1335), and R (1337), to make the CRIPSR/Cas9-VQR able to recognize the NGA PAM motif. We also constructed a binary expression vector of CRISRP/Cas9-VQR with maize ubiquitin as the promoter to drive the Cas9-VQR, optimizing SpCas9-codon, adding conserved nuclear localization signal sequence, and increasing the conserved 3' UTR sequence of monocots, and using OsU6 transcripts of sRNA. CRISPR/Cas9-VQR could recognize the NGA motif and cut targeted sequence in vivo. We assembled the Cas9-VQR protein with the sRNAs in vitro. The Cas9-VQR could cleave the targeted fragments with about 5%-70% of mutation efficiency. In the transformation of rice, we detected about 27.50%-70.50% of mutation ratio, with an average of 46.23%. This system broadens the CRISPR/Cas9 applications in crops, especially in these with higher PAM locus of NGA.

      Epistatic and QTL × environment interaction effects for ear related traits in two maize (Zea mays) populations under eight watering environments
      Xiao-Qiang ZHAO,Bin REN,Yun-Ling PENG,Ming-Xia XU,Peng FANG,Ze-Long ZHUANG,Jin-Wen ZHANG,Wen-Jing ZENG,Qiao-Hong GAO,Yong-Fu DING,Fen-Qi CHEN
      Acta Agronomica Sinica. 2019, 45(6):  856-871.  doi:10.3724/SP.J.1006.2019.83059
      Abstract ( 456 )   HTML ( 9 )   PDF (1590KB) ( 205 )   Save
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      Exploring genetic mechanisms of ear related traits in maize (Zea mays) under drought stress is important in maize molecular breeding for drought tolerance and high yield. Two F2:3 populations, namely 202 F2:3 families (LTPOP) and 218 F2:3 families (CTPOP) derived from the common male parent TS141 with drought-sensitive and larger ear and female parents Langhuang/Chang 7-2 with higher drought tolerance and small ear were used to investigate ear weight (EW), cob weight (CW), grain weight (GW), 100-kernel weight (KW), kernel ratio (KR), and ear length (EL) under eight watering environments, and then to analyze quantitative trait locus (QTL) in a single environment by composite interval mapping (CIM) and in the eight environments by mixed linear model based on composite interval mapping (MCIM). Sixty-two QTLs for ear related traits were detected in two F2:3 populations in a single environment by CIM, among than 38 QTLs were mapped under water-stressed environments, and further analysis showed that ten stable QTLs (sQTLs) were simultaneously identified in two F2:3 populations under multiple water-stressed environments, these sQTLs were located in Bin 1.01-1.03, Bin 1.03-1.04, Bin 1.05, Bin 1.07, Bin 1.07-1.08, Bin 2.04, Bin 4.08, Bin 5.06-5.07, Bin 6.05, and Bin 9.04-9.06. Fifty-four joint QTLs for ear related traits were identified in the eight environments by joint analysis with MCIM, among than 24 had significant QTL by environment interaction (QTL×E), and 17 significant epistatic interactions with additive by additive/dominance (AA/AD) effects, with less phenotypic variation. These results lay a foundation for systematically revealing molecular genetic mechanism of ear related traits, these sQTLs detected in two F2:3 populations under multiple environments are important genomic regions that could be used in positional cloning and molecular breeding for drought tolerance and high yield, however, more attention should be paid to the effects of environment or epistatic interaction.

      Development of efficient KASP molecular markers based on high throughput sequencing in maize
      Hai-Yan LU,Ling ZHOU,Feng LIN,Rui WANG,Feng-Ge WANG,Han ZHAO
      Acta Agronomica Sinica. 2019, 45(6):  872-878.  doi:10.3724/SP.J.1006.2019.83067
      Abstract ( 1282 )   HTML ( 51 )   PDF (2061KB) ( 570 )   Save
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      SNP (Single Nucleotide Polymorphism) which is abundant and dispersed widely in the genome is suitable for large-scale and automated genotyping. In this study, highly polymorphic bi-allelic SNP loci were screened and 700 KASP (Kompetitive Allele Specific PCR) molecular markers were developed based on resequencing data of 205 diverse maize inbred lines. Among them, 202 KASP markers validated by 46 representative lines were further used for phylogenetic tree construction and genetic structure analysis. The validated KASP markers distributed evenly on 10 chromosomes in maize with an average PIC of 0.463 and an average MAF of 0.451. The phylogenetic tree constructed by KASP markers is highly consistent with that by re-sequencing data. In addition, the genetic similarity coefficient evaluated between KASP loci and the total SNP loci achieved 89.5% which demonstrated the availability of KASP in heterotic group division. These findings suggest that 202 KASP markers play an important role in analysis of germplasm resource, construction of genetic map, and division of heterotic group in maize.

      Effects of supplemental irrigation with micro-sprinkling hoses on soil physical properties, water consumption and grain yield of winter wheat
      Xin-Nan HE,Xiang LIN,Shu-Bo GU,Dong WANG
      Acta Agronomica Sinica. 2019, 45(6):  879-892.  doi:10.3724/SP.J.1006.2019.81070
      Abstract ( 772 )   HTML ( 11 )   PDF (698KB) ( 344 )   Save
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      Water shortage is a major problem threatening agricultural sustainability, especially winter wheat production, in the Huang-Huai-Hai Plain of China and water-saving cultivation with limited irrigation is a promising technique in this area. It is important to explore the differences between border irrigation (BI) and micro-sprinkling supplemental irrigation (MSI) on soil physical properties, water consumption characteristics, yield and water use efficiency of winter wheat, which can provide theoretical and technical support for water-saving and high-yield cultivation of winter wheat in this region. In 2016 to 2018 winter wheat growing season, BI and MSI were set to study the effects of the two irrigation treatments on soil bulk density, total porosity, capillary porosity, field capacity in the 0-40 cm soil layer, as well as evaporation, evapotranspiration, grain yield and water use efficiency in each growth stage of winter wheat. Compared with BI treatment, MSI treatment decreased the bulk density, but increased the total porosity, capillary porosity and field capacity in 0-20 cm soil layer. In addition, the spring tiller after revival and the evaporation and evapotranspiration from revival to jointing and total water consumption were significantly reduced in MSI treatment. Grain yield was not significantly changed, but water use efficiency was significantly increased in MSI treatment. The above results suggest that MSI can improve the soil physical properties, optimize the population structure, and decrease total water consumption by reducing evaporation and ineffective evapotranspiration of plants, so as to enhance water use efficiency while maintaining high grain yield.

      TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY
      Effect of annual straw return model on soil carbon sequestration and crop yields in winter wheat-summer maize rotation farmland
      Hao-Yu LI,Zhao-Liang MENG,Dang-Wei PANG,Jin CHEN,Yong-Kun HOU,Hai-Xing CUI,Min JIN,Zhen-Lin WANG,Yong LI
      Acta Agronomica Sinica. 2019, 45(6):  893-903.  doi:10.3724/SP.J.1006.2019.81078
      Abstract ( 535 )   HTML ( 23 )   PDF (591KB) ( 425 )   Save
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      This study sought to determine the effects of different straw return patterns on the annual wheat-maize yield and soil organic carbon content (SOC) in the east area of Huang-Huai-Hai Plain. Four treatments were set up in the experiment: No straw return (NS), Summer maize-season straw return (SS), Winter wheat-season straw return (WS), and Double-season straw return (DS). SOC and aggregates classified by wet screening in 0-40 cm soil layers were measured. The straw return significantly decreased the soil bulk density and the mass proportion of micro-aggregate (< 0.25 mm), and increased the macro-aggregate of >5 mm, 5-2 mm, and 1-0.5 mm by 57.2%, 25.0%, and 13.7% on average suggesting straw return could accelerate soil aggregation and aggregate stability. MWD increased by 22.7%. Meanwhile, straw return not only increase SOC in 0-30 cm layers by 4.0% to 20.7%, and SCS by 0.2% to 14.7%, but also markedly increased the SOC of aggregates and carbon preservation capacity. The straw returning amount was correlated related with SOC, and SOC was positively correlated with MWD in 0-30 cm soil layers. In the 30-40 cm soil layer, both SOC of aggregates and carbon preservation capacity among treatments were not significantly different. The highest grain yield was observed in DS with the increased annual crop yield by 14.3%. Consequently, the double-season straw return model is a good option for improving soil quality in winter wheat-summer maize rotation systems; however, single-straw incorporation could maintain higher soil production, and provide abundant straw feed, energy and raw materials.

      Adjustment and compensation of cotton to physical damage at early squaring stage
      He-Quan LU,Jie QI,Jian-Long DAI,Yan-Jun ZHANG,Xiang-Qiang KONG,Zhen-Huai LI,Wei-Jiang LI,Shi-Zhen XU,Wei TANG,Dong-Mei ZHANG,Zhen LUO,Cheng-Song XIN,Xue-Zhen SUN,He-Zhong DONG
      Acta Agronomica Sinica. 2019, 45(6):  904-911.  doi:10.3724/SP.J.1006.2019.84131
      Abstract ( 553 )   HTML ( 4 )   PDF (8016KB) ( 189 )   Save
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      Hail-caused physical damage on cotton often occurs at squaring in Yellow River basin. Cotton is characterized as indeterminate growth habit as well as great compensatory ability. It is very important to determine the recovery potential after physical damage. A two-year (2014-2015) field experiment was carried out at Linqing of Shandong province with six treatments at five days after squaring, including removal of main-stem terminal and total leaves, RTL; removal of main-stem terminal but one leaf maintained, RT+1LM; removal of main-stem terminal but total leaves maintained, RT+ALM; main-stem terminal maintained but removal of total leaves, TM+RL; main-stem terminal and one leaf maintained, TM+1LM; and non-damaged, CK. A randomized blocks design was used for the study. Results showed that dry weight of single plant in RTL, RT+1LM, RT+ALM and TM+RL was significantly reduced at 15-60 days after treatment (DAT) as compared with that of CK. Dry weight of single plant in TM+1LM was reduced by 59.0% and 12.1% at 15 and 30 DAT, respectively, and slightly reduced at 45 and 60 DAT. LAI dynamics of six treatments were similar to those of biomass from 15 to 60 DAT. The leaf net photosynthetic rate of RTL, RT+1LM, RT+ALM and TM+RL was lower than that of control from 15 to 45 DAT, and the peak occurrence of Pn was delayed, while the Pn of TM+1LM and its peak period were similar to that of CK. Total biomass TM+RL was reduced by 18.2% in, but not changed in RTL, RT+1LM, RT+ALM, and TM+1LM compared with that of CK. Ratio of seedcotton to stalk of RTL, RT+1LM, RT+ALM, and TM+RL was decreased by 52.6%, 47.3%, 36.8%, and 23.7% compared with that of CK, but not significantly changes in TM+1LM. The number of bolls per unit land area in RTL, RT+1LM, RT+ALM, and TM+RL decreased by 19%, 7.2%, 9.9%, and 15.6%, boll weight decreased by 23.2%, 8.9%, 8.9%, and 19.6%, and thus seedcotton yield decreased by 36.3%, 17.5%, 15.5%, and 31.9%, respectively. However, TM+1LM did not significantly reduce the number of bolls and boll weight, and produced comparable yield to CK. The results of this study indicate that cotton plants have strong compensation effects on biological yield and economic yield owing to the indeterminate growth habit after physical damage at squaring stage, but the compensatory effects are varied by the extent of physical damage. Accordingly, the physical injury at squaring was divided into light injury (TM+1LM), moderate injury (RT+1LM, RT+ALM), and severe injury (RTL, TM+RL), in which the yield reduction was less than 5%, 15%, and more than 30%, respectively. For lightly and moderately damaged cotton fields, water and fertilizer management is strongly recommended to promote cotton compensatory growth and reduce yield losses, while for seriously damaged cotton fields, replanting other short-season crops could be considered.

      Effect of phosphorus (P) on nitrogen (N) uptake and utilization in peanut
      Tian-Yi YU,Xiao-Liang LI,Ya LU,Xue-Wu SUN,Yong-Mei ZHENG,Zheng-Feng WU,Pu SHEN,Cai-Bin WANG
      Acta Agronomica Sinica. 2019, 45(6):  912-921.  doi:10.3724/SP.J.1006.2019.84107
      Abstract ( 555 )   HTML ( 15 )   PDF (391KB) ( 301 )   Save
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      P is one of the essential nutrients to plant and influences N uptake and utilization of crops by various ways. Peanut belongs to leguminous plant, which N nutrition is obtained from soil, fertilizer and nodule N fixation. This study is significant for fully developing the potential of N fixation and reducing dependence on N fertilizer. Two popularized cultivars (big pod cultivar Huayu 22 and small pod cultivar Huayu 20) in Shandong province were chosen and five P (P2O5) application levels (0, 45, 90, 135, and 180 kg ha -1) were applied in a two-year barrel experiment, to investigate the influences of P on uptake and utilization of three N sources for peanut with 15N isotope tracing analysis. The N accumulation amounts from the three N sources in two varieties all increased with increasing P-level. The increment of N accumulation amount from nodule N fixation was larger than that from soil N and fertilizer N. And the change trends for different varieties and years were almost the same. Nodule numbers, fresh weights and percentages of N accumulation amounts form nodule N fixation increased with the increase of P application rate, while the percentages of N accumulation amounts form soil N and fertilizer N declined. In the P range of 45-90 kg ha -1, nitrogen use efficiency (NUE), nitrogen pod production efficiency (NPPE), and pod yield increased with increasing P-level. However, the three parameters decreased or did not increase any more with further more P application. In addition, the agronomic efficiency of P fertilizer decreased with the increase of P application rate. N accumulation amount from nodule N fixation had extremely significant and positive correlation with pod yield and total N accumulation amount of plant, and significantly negative correlation with percentages of N accumulation amounts from soil N and fertilizer N, NUE, and NPPE. And the percentage of N accumulation amount from nodule N fixation had extremely significant and negative correlation with N accumulation amounts and percentages of fertilizer N, soil N and NUE. In conclusion, applying P fertilizer could increase N supplying amount and percentage from nodule N fixation of peanut and reduce dependence on fertilizer N and soil N. However, excess P fertilizer is not benefit for N, P efficiency and pod yield. The suitable P rate for peanut is 45-90 kg ha -1.

      Characteristics of maize grain dehydration and prediction of suitable harvest period in Liao River Basin
      Zhao-Fu HUANG,Bo MING,Ke-Ru WANG,Rui-Zhi XIE,Fei YANG,Zhi-Gang WANG,Chun-Hua XIAO,Shao-Kun LI
      Acta Agronomica Sinica. 2019, 45(6):  922-931.  doi:10.3724/SP.J.1006.2019.83062
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      Liao River Basin (LRB) is located in the south of the northeast China, mainly planting spring maize. The technology of grain mechanical harvesting is promoted based on the better thermal resources in LRB, but it is impeded by the higher grain moisture at harvest, higher grain broken rate and higher yield loss rate. In order to solve problem, characteristics of grain dehydration of main cultivars need to be researched and the suitable harvesting time ought to be determined based on the thermal resources. The study was aimed at selecting suitable cultivars and evaluating the quality of grain mechanical harvesting. In 2017, the 29 maize cultivars with different maturity periods were weed to investigate grain dehydration dynamics in Kailu county and Tieling county. On the basis of the analysis results of sowing date of perennial spring maize in the basin, growth and development of different varieties, demand of grain dehydration accumulated temperature and historical meteorological data, the prediction method of suitable mechanical grain harvest period for different varieties was established in LRB. Logistic Power model was used to match the dynamic process of grain dehydration of spring maize. There was a significant linear relationship between the actual grain moisture at harvest and the simulated grain moisture (R 2= 0.916, RMSE = 1.217), showing an excellent regional adaptability of this model. Using four cultivars suitable for grain mechanical harvest in 2017 national trial and two main cultivars grown in LRB, distribution regulations of the suitable harvest period were clarified. Among the four cultivars, the actively accumulated temperature requirements of Deyu 919 and Jingnongke 728 were less than 3122°C d from sowing to the stage with grain moisture reducing to 25%, showing that the better period of grain mechanical harvest was in the middle and late September in most parts of LRB. While the other two cultivars of Zeyu 8911 and Jidan66 had accumulated temperature requirements 3400°C d, and suitable harvest period in early October which was roughly 10-20 days behind there of the two former cultivars. As less than for the two main cultivars—Liaodan 575 and Jingke 968, their requirements of accumulated temperature were 200°C d more than there of Zeyu 8911 and Jidan66, which is difficult to achieve a high-quality mechanical grain harvesting at normal time. The research verified the application accuracy of the predicting model of grain moisture established based on Logistic Power model. Comparing the changes of grain moisture content, the accumulated temperature requirements to maturity and dehydration, and spatial distribution regulations of suitable period of grain mechanical harvesting between national trial cultivars and local main cultivars, and updating the existing cultivars and helpful to achieve high-quality mechanical grain harvesting in the LRB.

      Assessment of the nitrogen footprint in oilseed rape production of China during 2004 to 2015 base on life cycle assessment method
      Zhong-Du CHEN,Chun-Chun XU,Long JI,Fu-Ping FANG
      Acta Agronomica Sinica. 2019, 45(6):  932-940.  doi:10.3724/SP.J.1006.2019.84112
      Abstract ( 400 )   HTML ( 7 )   PDF (2059KB) ( 226 )   Save
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      The loss of reactive nitrogen in agriculture has increasingly become serious, systematic analysis of reactive nitrogen emissions from agricultural production is conducive to promoting the green and healthy development of agriculture in China. Based on the statistical data of crop yield and farmland investment in the oilseed rape production of China, the spatiotemporal dynamic change of nitrogen footprint (NF) and its composition of oilseed rape during 2004-2015 in China was estimated using the theory of NF and life cycle assessment method in the agricultural sector. The NF of oilseed rape was 7572.0 g N-eq ha -1 during 2004-2015, and decreasing year by year, with an average annual decline of 1.0%. The main components of the NF were from fertilizer application (20%) and NH3 emission (54%) in the oilseed rape production. Obvious differences also were observed among mainly agricultural provinces in China, that is, the higher nitrogen footprint per area (NFa) and nitrogen footprint per yield (NFy) in Inner Mongolia, Shanghai, and Jiangsu region. The NFa and NFy in high yield region were significantly higher than those in low yield region. Among them, the NF of nitrogenous fertilizer, phosphate fertilizer and compound fertilizer increased by 80.6%, 76.9%, and 57.8%, respectively (P < 0.05). The NFa of rapeseed in China showed a trend of increase with the increase of rapeseed yield, but there was no significant correlation. The results suggest that improving crop management practices that limit fertilizer consumption is an important measure for the green and healthy development of rapeseed in China.

      RESEARCH NOTES
      Effects of combined application of nitrogen and potassium on seed yield and nitrogen utilization of winter oilseed rape (Brassica napus L.)
      Jing LI,Jin-Yao YAN,Wen-Shi HU,Xiao-Kun LI,Ri-Huan CONG,Tao REN,Jian-Wei LU
      Acta Agronomica Sinica. 2019, 45(6):  941-948.  doi:10.3724/SP.J.1006.2019.84146
      Abstract ( 478 )   HTML ( 12 )   PDF (812KB) ( 406 )   Save
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      The imbalance inputs of nitrogen (N) and potassium (K) fertilizer in current agricultural production severely restricts fertilizer use efficiency and crop yield potential. In order to estimate the influence of K fertilizer application on rapeseed yield and N fertilizer use efficiency under different nitrogen application rates, field experiments using two-factor experimental design were conducted at Wuxue county, Hubei province in 2016/2017 and 2017/2018 winter oilseed rape growing seasons. Four levels of N and K fertilizer application rates were set up, which were 0, 90, 180, 270 kg N ha -1 and 0, 60, 120, 180 kg K2O ha -1, respectively. Seed yield, shoot N and K accumulation and N fertilizer use efficiency were measured at the harvest of winter oilseed rape. When K supply was insufficient (K0 and K60), the average increase rate of seed yield was 113.7%, while under sufficient K supplies (K120 and K180), the average seed yield increase rate was 172.9%. In contrast to the K0 treatment, the K120 treatment increased N fertilizer use efficiency by 16.6% on average; nevertheless, further increase K fertilizer application rate played minor role in the improvement of N fertilizer use efficiency. Considering the regional average rapeseed yield, adequate K supply could reduce the N fertilizer application rate with the average of 33.9% compared with insufficient K fertilization (K60). Consequently, the combined application of N and K fertilizers could significantly enhance rapeseed yield and N fertilizer use efficiency. In practices, besides paying more attention to N fertilizer application, K fertilizer input also should be strengthened. Optimizing N and K fertilizer application could be beneficial to further achieving higher seed yield and higher fertilizer use efficiency.

      Responses of leaf gas exchange to high temperature and drought combination as well as re-watering of winter wheat under doubling atmospheric CO2 concentration
      Li-Li GUO,Xi-Xi ZHANG,Li-Hua HAO,Ya-Jun QIAO,Wen-Na CHEN,Yun-Ze LU,Fei LI,Xu CAO,Qing-Tao WANG,Yun-Pu ZHENG
      Acta Agronomica Sinica. 2019, 45(6):  949-956.  doi:10.3724/SP.J.1006.2019.81081
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      Understanding the responsible mechanisms of crops to combined environmental stresses such as elevated CO2 concentration, climate warming, and drought is critical to improve the accuracy of ecological process models, and thus accurately predict the impacts of global climate change on the Net Primary Production (NPP) and ecosystem service function of farmlands. Four environmental growth chambers accurately controlling CO2 concentration and temperature were employed to investigate the combined effects of high temperature and drought stresses on the stomatal traits and leaf gas exchange during re-watering under doubling CO2 concentration. We found that elevated CO2 concentration (E) increased the stomatal density, decreased the stomatal width and made the spatial distribution pattern of stomata irregular on the abaxial leaf surface, while enhanced the net photosynthetic rates (Pn), stomatal conductance (Gs), transpiration rates (Tr), and water use efficiency (WUE). The stomatal length, width, perimeter and area were substantially decreased under the combined high temperature and drought stress (HD), resulting in dramatic decline of leaf gas exchange parameters. Doubling CO2 concentration made the leaf gas exchange parameters enhanced under the HD treatment, suggesting that elevated CO2 concentration can compensate the negative impacts of heat and drought on the physiological processes of winter wheat. Additionally, the leaf gas exchange of winter wheat subjected to the high temperature and drought stresses was enhanced after re-watering, but these parameters were still lower than those of Control, suggesting that the photosynthetic apparatus may be damaged by the combined high temperature and drought stresses.

      Effect of lower water and nitrogen supply on grain yield and dry matter remobilization of organs in different layers of winter wheat plant in northern Henan province
      Li-Na JIANG,Jing-Li MA,Bao-Ting FANG,Jian-Hui MA,Chun-Xi LI,Zhi-Min WANG,Bao-Zhen HAO
      Acta Agronomica Sinica. 2019, 45(6):  957-966.  doi:10.3724/SP.J.1006.2019.81068
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      Reducing irrigation and N fertilizer application is an inevitable option to meet the target of enhancing grain yield, improving nutrient use efficiency and developing friendly environment in winter wheat production of northern Henan province. Clarifying effects of lower water and nitrogen supply on grain yield and dry matter remobilization of organs in different layers of wheat plant can provide scientific basis for rational N fertilizer inputs in wheat production with limited irrigation in Northern Henan province. A field experiment was carried out at the Xun County Experimental Station, Henan province by a split-plot design with water regime as the main plot and N rate as sub-plot factor in 2009-2010 and 2010-2011 growing seasons. There were two water regimes: W1 (irrigation of 75 mm water at stem elongation stage) and W2 (irrigation of 75 mm water at stem elongation stage plus 75 mm at anthesis), and five nitrogen (N) treatments: 120+210 kg ha -1 (N4, traditional N application rate with pre-sowing N and top-dressed N at elongation), 120+150 kg ha -1 (N3), 120+90 kg ha -1 (N2), 120+0 kg ha -1 (N1), and 0+0 kg ha -1 (N0). Grain yield and dry matter remobilization amount, dry matter remobilization efficiency, contribution rate of dry matter remobilization to grain of individual organs of wheat plant were analyzed. Compared with N4, the treatments of decreased N rate increased the amount, efficiency and contribution rate to grain of dry matter remobilization in vegetative organs, among them the dry matter remobilization amount of chaff increased by 323.2%, which was higher than that of stem (24.5%) and leaf (4.6%), as well as dry matter remobilization efficiency and contribution rate of dry matter remobilization to grain in chaff increased by 313.7% and 77.0%, respectively, which were higher than those in stem (30.9% and 36.8%) and leaf (17.8% and 13.4%). The increase of dry matter remobilization from leaf in treatments of decreased N rates was mainly attributed to the increased dry matter remobilization amount from the 3rd leaf and 4th leaf, which was 28.7% and 201.1%, respectively. Similarly, the increase of dry matter remobilization from stem in treatments of decreased N rates was mainly attributed to the increased dry matter accumulation amount from the 2nd internode, the 3rd internode, the 4th internode and residue internodes, which was 21.7%, 71.8%, 44.5%, and 31.1%, respectively. There were no signi?cant differences in dry matter accumulation amount between W1 and W2, with slight higher dry matter remobilization efficiency in W1 (24.6%) than in W2 (23.8%), and higher contribution rate of dry matter remobilization to grain in W1 (35.1%) than in W2 (30.0%). Compared with W2, W1 reduced grain yield by 11.2% with a water reduction of 750 m 3ha -1. The results indicate that lower nitrogen supply enhances the dry matter remobilization from wheat vegetative organs to grains, improving the contribution rate of dry matter remobilization to grain, which is mainly contributed by chaff and lower layer organs (the 3rd leaf, the 4th leaf, the 3rd internode, the 4th internode and residue internodes), but not by upper layer organs.

Co-sponsored:
the Crop Science Society of China
the Institute of Crop Science, CAAS
China Science Publishing & Media Ltd.
Published: Science Press
Editor-in-chief: Wan Jian-min
Associate Editors-in-Chief:
Chen Xiao-ya Yang Jian-chang Zhang Xian-long Wang Jian-kang Xu Ming-liang Liu Chun-ming Wang Dao-wen Sun Chuan-qing Ding Yan-feng Jin Wei-wei Chu Cheng-cai Cheng Wei-hong
Director of the editorial department:
Cheng Wei-hong
CN 11-1809/S
ISSN 0496-3490
Post subscription code: 82-336

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  • Started in 2013
  • Covered by SCIE
  • Open access in ScienceDirect

Editor in chief: Wan Jian-min
CN 10-1112/S
ISSN 2095-5421, 2214-5141(online)
Online published:
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E-mail: cropjournal@caas.cn
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