氮（N）是植物和土壤微生物必需的营养元素，但陆地生态系统常受到N限制。目前，有关不同植被斑块类型如何影响草原生态系统中植物与土壤微生物之间N分配的研究仍存在不足。选取青藏高原退化高寒草原5种常见的植被斑块进行¹⁵N标记实验（¹⁵N-NO₃⁻和¹⁵N-NH₄⁺），对不同植被斑块类型下植物和微生物的N获取策略进行研究。结果表明，5种植被斑块中植物和土壤微生物均偏好吸收NO₃⁻。适口性较好植物斑块中的植物N吸收量显著高于植被适口性较差斑块中的植物，而植被适口性较差斑块中的土壤微生物N吸收量则显著高于植被适口性较好的斑块。5种植被斑块类型中亚早熟禾（Poa litwinowiana）斑块中植物的N吸收量最高（NO₃⁻：13.32–51.28 mg m^-2；NH₄⁺：0.35–1.36 mg m^-2），而冰川棘豆（Oxytropis glacialis）斑块中土壤微生物的N吸收量最高（NO₃⁻：846.97–1659.87 mg m^-2；NH₄⁺：108.75–185.14 mg m^-2）。所有植被斑块中土壤微生物N吸收量高于植物N吸收量（即微生物氮吸收与植物氮吸收之比大于1）。随着高寒草原植被退化程度的加剧，植物的N吸收能力下降，而土壤微生物的N吸收能力增强。土壤微生物较强的N竞争能力可能会降低植物的营养吸收，对N素限制的高寒草原植被恢复产生不利影响。

糖是植物生长发育中不可或缺的生长能源，在通过疏水屏障时需要糖转运蛋白（STP）的帮助。当玉米受到病原体侵染时，糖的含量会产生波动，但是糖转运蛋白如何在玉米抗病过程中发挥作用还没有清晰地研究。为了鉴定玉米(Zea mays)糖转运蛋白家族成员并分析其在不同组织和生理条件下的表达规律，本研究利用生物信息学方法对玉米基因组中糖转运蛋白编码基因进行了系统性鉴定和分析，利用同源性分析鉴定玉米糖转运蛋白编码基因，利用保守结构域分析对糖转运蛋白进行结构域鉴定，利用转录组数据对糖转运蛋白编码基因进行表达规律分析，利用激素处理试验，验证了该家族成员在激素处理下的表达规律，并利用病斑侵染突变体，验证了该家族成员ZmSTP2和ZmSTP20具有抗病性。结果表明，玉米糖转运蛋白家族包含24个成员，均预测分布在细胞膜上，具有高度保守的跨膜转运结构域，玉米糖转运蛋白编码基因在不同组织中和胁迫下表达水平有明显差异，其中ZmSTP2和ZmSTP20在禾谷镰孢（Fusarium graminearum）侵染后表达水平持续上升，通过对zmstp2和zmstp20突变体进行抗病分析，发现接种玉米圆斑菌（Cochliobolus carbonum）、玉米大斑菌（Setosphaeria turcica）、玉米小斑菌（Cochliobolus heterostrophus）和禾谷镰孢（F. graminearum）后，zmstp2和zmstp20突变体的病斑面积显著高于野生型B73。本研究在全基因组层面对玉米糖转运蛋白编码基因进行了系统性鉴定和分析，明确了玉米糖转运蛋白的编码基因，揭示了糖转运蛋白编码基因在玉米不同组织及生物和非生物胁迫中的表达规律，为进一步阐明其功能奠定了重要的理论基础。

肌纤维是骨骼肌的主要组成部分，由肌管成熟形成。在早期发育过程中，骨骼肌卫星细胞（SSCs）增殖为成肌细胞，随后成肌细胞经历分化和融合形成肌管。然而，从SSCs到肌管转化过渡机制仍不清晰。因此，本研究采用了RNA-seq和DIA技术对山羊肌卫星细胞、成肌细胞（分化2天）和肌管（分化10天）进行了转录组和蛋白组测序。首先，对两个组学分别进行了差异分析，转录组中共鉴定到5785个差异基因，蛋白组中共鉴定到2946个差异蛋白。蛋白质组分析发现SLMAP和STOM可能与肌管的形成有关。沉默SLMAP后，成肌标记基因MyoD的明显上调（P<0.01）和肌管标记基因MyoG和Myosin7明显下调（P<0.01），但Desmin的表达水平没有变化；沉默STOM后，成肌标记基因MyoD的明显上调（P<0.01）和肌管标记基因MyoG、Myosin7和Desmin均明显下调（P<0.01）。在更严格的差异分析条件下（差异蛋白|log2(FC)|>1.2；差异基因|log2(FC)|>2)）整合两个组学数据发现，在肌卫星细胞和成肌细胞比较组中，18个因子呈正相关，37个因子呈负相关；在成肌细胞和肌管比较组中，31个因子呈正相关，10个因子呈负相关。这些因子的GO分析表明，从肌卫星细胞到成肌细胞转变时，分化和迁移相关的因子SVIL、ENSCHIG00000026624（AQP1）、SERPINE1上调，同时伴随着细胞凋亡。在成肌细胞到肌管转变时，与细胞粘附和信号转导有关的候选因子在肌管中高度表达，CCN2、TGFB1、MYL2和MYL4被确定为成肌细胞和肌管比较组的关键候选因子。综上，本研究从转录组和蛋白组中筛选到了可能影响肌卫星细胞到成肌细胞，再到肌管转变的关键因子，对肌肉早期发育或损伤后再生过程中肌管形成提供新的解析。

前期研究表明，灰葡萄孢BcSDR1基因参与调控病菌的生长发育和致病过程。然而，BcSDR1的调控机制以及BcSDR1与cAMP和MAPK信号通路的关系还不是很清楚。本研究中，转录组数据显示，BcSDR1参与了葡萄糖跨膜运输、信号转导、次级代谢等生物过程。BcSDR1突变体（BCt41）对cAMP和MAPK信号通路特异性抑制剂SQ22536和U0126的敏感性非常弱，cAMP含量明显下降。进一步通过qRT-PCR 来检测cAMP和MAPK信号通路的关键基因的表达量，发现BcSDR1突变体中BcGB1、BcBTP1、BcBOS1、BcRAS1和BcBMP3明显上调，而BcPLC1、BcBCG1、BcCDC4、BcSAK1、BcATF1和BcBAP1明显下调。BcSDR1在BcBCG2、BcBCG3、BcPKA1和BcPKAR的RNAi突变体中明显上调，但在BcPKA2、BcBMP1和BcBMP3的RNAi突变体中显著下调。因此，BcBCG2、BcBCG3、BcPKA1和BcPKAR负向调节BcSDR1的表达，而BcPKA2、BcBMP1和BcBMP3正向调节BcSDR1表达。本研究可为制定持久控制灰霉病的策略提供理论依据和实践基础，同时为研究其他真菌的遗传、发育和致病性提供重要参考价值依据。

本研究通过抗原性分析发现，2020年至2021年在野鸟或家禽中分离的一些H5N6、H5N8和H5N1病毒与我国大规模应用的H5疫苗种毒株(H5-Re11株和H5-Re12株)的抗原性存在较大差异，部分2021年分离的H7N9病毒也与我国使用的H7-Re3株疫苗毒株存在抗原性差异。为保持疫苗株与监测毒株之间良好的抗原匹配性，本研究利用反向遗传学操作技术，构建出针对抗原变异毒株的3株重组疫苗种毒（H5-Re13、H5-Re14和H7-Re4），用于疫苗的更新。其中，H5-Re13疫苗株的HA和NA基因来自于2.3.4.4h分支的H5N6病毒（DK/FJ/S1424/20），H5-Re14疫苗株的HA和NA基因来自于2.3.4.4b分支的H5N8病毒（WS/SX/4-1/20），H7-Re4疫苗株的HA和NA基因来自于2021年分离的H7N9病毒（CK/YN/SD024/21）。进一步使用上述3株重组病毒制备新型H5+H7三价灭活疫苗，进行鸡、鸭和鹅的免疫效力研究。结果显示，H5+H7三价灭活疫苗接种鸡、鸭和鹅后均可诱导出良好的HI抗体反应；SPF鸡接种疫苗后3周时，用2020年和2021年分离到的5株不同H5和H7病毒攻击，包括3株2.3.4.4b分支病毒（H5N1、H5N6和H5N8病毒各1株）、1株2.3.4.4h分支的H5N6病毒和1株H7N9病毒，攻毒后所有对照组鸡均出现高滴度的排毒，并在攻毒后4天内全部死亡，而疫苗接种组鸡则完全抵御病毒的感染；接种疫苗的鸭和鹅在攻击2.3.4.4h或2.3.4.4b分支H5病毒后也获得完全免疫保护。本研究结果表明，新型H5+H7三价疫苗具有良好的免疫原性,对于近期监测到的H5N1、H5N6、H5N8和H7N9病毒的攻击可提供完全的免疫保护作用。鉴于不同H5病毒和H7N9病毒对家禽的威胁，本研究建议我国广泛使用该H5+H7三价灭活疫苗，并推荐该疫苗在其他受到H5和H7病毒威胁的国家应用。

Soil productivity (SP) without external fertilization influence is an important indicator for the capacity of a soil to support crop yield. However, there have been difficulties in estimating values of SPs for soils after various long-term field treatments because the treatment without external fertilization is used but is depleted in soil nutrients, leading to erroneous estimation. The objectives of this study were to estimate the change of SP across different cropping seasons using pot experiments, and to evaluate the steady SP value (which is defined by the basal contribution of soil itself to crop yield) after various longterm fertilization treatments in soils at different geographical locations. The pot experiments were conducted in Jinxian of Jiangxi Province with paddy soil, Zhengzhou of Henan Province with fluvo-aquic soil, and Gongzhuling of Jilin Province with black soils, China. Soils were collected after long-term field fertilization treatments of no fertilizer (control; CK-F), chemical fertilizer (NPK-F), and combined chemical fertilizer with manure (NPKM-F). The soils received either no fertilizer (F0) or chemical fertilizer (F1) for 3–6 cropping seasons in pots, which include CK-P (control; no fertilizer from long-term field experiments for pot experiments), NPK-P (chemical fertilizer from long-term field experiments for pot experiments), and NPKM-P (combined chemical and organic fertilizers from long-term field experiments for pot experiments). The yield data were used to calculate SP values. The initial SP values were high, but decreased rapidly until a relatively steady SP was achieved at or after about three cropping seasons for paddy and fluvo-aquic soils. The steady SP values in the third cropping season from CK-P, NPK-P, and NPKM-P treatments were 37.7, 44.1, and 50.0% in the paddy soil, 34.2, 38.1, and 50.0% in the fluvo-aquic soil, with the highest value observed in the NPKM-P treatment for all soils. However, further research is required in the black soils to incorporate more than three cropping seasons. The partial least squares path mode (PLS-PM) showed that total N (nitrogen) and C/N ratio (the ratio of soil organic carbon and total N) had positive effects on the steady SP for all three soils. These findings confirm the significance of the incorporation of manure for attaining high soil productivity. Regulation of the soil C/N ratio was the other main factor for steady SP through fertilization management.

North China Plain (NCP) is the primary winter wheat production region in China, characterized by smallholder farming systems.  Whereas the winter wheat average yield of smallholder farmers is currently low, the yield potential and limiting factors driving the current yield gap remain unclear.  Therefore, increasing the wheat yield in NCP is essential for the national food security.  This study monitored wheat yield, management practices and soil nutrient data in 132 farmers’ fields of Xushui County, Baoding City, Hebei Province during 2014–2016.  These data were analyzed using variance and path analysis to determine the yield gap and the contribution of yield components (i.e., spikes per hectare, grain number per spike and 1 000-grain weight) to wheat yield.  Then, the limiting factors of yield components and the optimizing strategies were identified by a boundary line approach.  The results showed that the attainable potential yield for winter wheat was 10 514 kg ha^–1.  The yield gaps varied strongly between three yield groups (i.e., high, middle and low), which were divided by yield level and contained 44 farmers in each group, and amounted to 2 493, 1 636 and 814 kg ha^–1, respectively.  For the three yield components, only spikes per hectare was significantly different (P<0.01) among the three yield groups.  For all 132 farmers’ fields, correlation between yield and spikes per hectare (r=0.51, P<0.01), was significantly positive, while correlations with grain number per spike (r=–0.16) and 1 000-grain weight (r=–0.10) were not significant.  The path analysis also showed that the spikes per hectare of winter wheat were the most important component to the wheat yield.  Boundary line analysis showed that seeding date was the most limiting factor of spikes per hectare with the highest contribution rate (26.7%), followed by basal N input (22.1%) and seeding rate (14.5%), which indicated that management factors in the seeding step were the most important for affecting spikes per hectare.  For desired spikes per hectare (>6.598×106 ha^–1), the seeding rate should range from 210–300 kg ha^–1, seeding date should range from 3th to 8th October, and basal N input should range from 90–180 kg ha^–1.  Compared to these reasonable ranges of management measures, most of the farmers’ practices were not suitable, and both lower and higher levels of management existed.  It is concluded that the strategies for optimizing yield components could be achieved by improving wheat seeding quality and optimizing farmers’ nutrient management practices in the NCP.

Nitrogen is an important nutrient for plant development.  Nitrogen and carbon metabolisms are tightly linked to physiological functions in plants.  In this study, we found that the IbSnRK1 gene was induced by Ca(NO₃)₂.  Its overexpression enhanced nitrogen uptake and carbon assimilation in transgenic sweetpotato.  After Ca(¹⁵NO₃)₂ treatment, the 15N atom excess, 15N and total N content and nitrogen uptake efficiency (NUE) were significantly increased in the roots, stems, and leaves of transgenic plants compared with wild type (WT) and empty vector control (VC).  After Ca(NO₃)₂ treatment, the increased nitrate N content, nitrate reductase (NR) activity, free amino acid content, and soluble protein content were found in the roots or leaves of transgenic plants.  The photosynthesis and carbon assimilation were enhanced.  These results suggest that the IbSnRK1 gene play a important role in nitrogen uptake and carbon assimilation of sweetpotato.  This gene has the potential to be used for improving the yield and quality of sweetpotato.

Received  3 March, 2018    Accepted  2 April, 2018

Blumeria graminis f. sp. tritici, the pathogen that causes wheat powdery mildew, is one of the most important diseases affecting wheat production in China, and the oversummering is the key stage of wheat powdery mildew epidemic.  The more oversummering regionalization of wheat powdery mildew has played an important role in disease prediction, prevention and control.  In this study, we analyzed the correlation between oversummering data of wheat powdery mildew and the meteorological factors over the past years, and determined that temperature was the key meteorological factor influencing oversummering of wheat powdery mildew.  The average temperature at which wheat powdery mildew growth was terminated (26.2°C) was used as the threshold temperature to regionalize the oversummering range of wheat powdery mildew.  This regionalization was done using the GIS ordinary kriging method combined with the Digital Elevation model (DEM) of China.  The results showed that annual probability of oversummering region based on Model 26.2 were consistent with the actual survey of the more summer wheat powdery mildew.  Wheat powdery mildew oversummering regions in China mainly cover mountainous or high-altitude areas, and these regions form a narrow north-south oversummering zone.  Oversummering regions of wheat powdery mildew is mainly concentrated in the high-altitude wheat growing areas, including northern and southern Yunnan, northwestern Guizhou, northern and southern Sichuan, northern and southern Chongqing, eastern and southern Gansu, southeastern Ningxia, northern and southern Shaanxi, central Shanxi, western Hubei, western Henan, northern and western Hebei, western Liaoning, eastern Tibet, eastern Qinghai, western Xinjiang and other regions of China.

Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper.  Meanwhile, the optimal negative pressure water supply conditions for growth of C. annuum L. were screened out to achieve the goals of water conservation, high yield and high quality, thus providing theoretical foundation for its field production.  The pot experiment within the greenhouse was utilized; the continuous negative pressure water supply was adopted; the four treatments, artificial watering (CK), –5 kPa (T1), –10 kPa (T2), and –15 kPa (T3) were set; and the daily water consumption, yield, as well as the biomass, nitrate reductase, root activity, vitamin C, capsaicin, and nutrient uptakes of nitrogen (N), phosphorus (P) and potassium (K) during various stages of its growth were determined.  Compared with CK, when the water supply pressure was controlled at –5 to –15 kPa in the experiment, the total water consumption of C. annuum L. reduced by 53.42 to 67.75%, the total water consumption intensity reduced by 54.29 to 67.14%, and the water use efficiency increased by 12.66 to 124.67%.  The N accumulation in a single strain of C. annuum L. from the color turning stage to the red ripe stage increased by 15.99 to 100.55%, respectively, compared with that of CK; the P accumulation increased by 20.47 to 154.00% relative to that of CK, and the K accumulation increased by 64.92 to 144.9% compared with that of CK.  Compared with CK, C. annuum L. yield was remarkably improved by 13.79% at T1, and contents of vitamin C, capsaicin as well as carotenoids at all growth stages were enhanced by 13.42–147.01%, 11.54–71.01%, and 41.1–568.06%, respectively.  Nitrate reductase activity, root activity and chlorophyll (a+b) were markedly increased by 335.78–500%, 79.6–140.68% and 114.95–676.19%, respectively, from immature stage to full ripe stage.  Adopting the continuous negative pressure water supply for C. annuum L. has a significant water-saving effect, and the water supply pressure being stable at –5 kPa contributes to its growth and development, improves yield, enhances root activity, promotes nutrient uptake, and improves its quality, thus achieving the effects of water conservation, high yield, high quality and high efficiency.

   The erect panicle (Ep) type is an important characteristic for japonica super rice in Northeast China and plays a significant role in enhancing yield. The Ep type is considered to be a genetic ideotype resource to the japonica super rice group by virtue of its agronomic advantages such as grain number per panicle and biomass. This study addresses the effects of nitrogen and planting density conditions on yielding performance regarding panicle type (PT) using the recombinant inbred line (RIL) population derived from the cross between an Ep variety Liaogeng 5 and non-Ep variety Wanlun 422. The genetics underlying the Ep type proved to be robust not only for panicle-type optimization but also plant height, panicle length, flag leaf length and seed density. We also found that regardless of nitrogen and density, correlation between harvest index (HI) and plant height was not significant in Ep type whatever the nitrogen and density. The application of Ep type provides a potential strategy for yield improvement by increasing biomass through HI maintainable in rice.

The objective of this study was to investigate the effects of applying different amounts of water and nitrogen on yield, fruit quality, water use efficiency (WUE), irrigation water use efficiency (IWUE) and nitrogen use efficiency (NUE) of drip-irrigated greenhouse tomatoes in northwestern China.  The plants were irrigated every seven days at various proportions of 20-cm pan evaporation (E_p).  The experiment consisted of three irrigation levels (I1, 50% E_p; I2, 75% E_p; and I3, 100% E_p) and three N application levels (N1, 150 kg N ha^–1; N2, 250 kg N ha^–1; and N3, 350 kg N ha^–1).  Tomato yield increased with the amount of applied irrigation water in I2 and then decreased in I3.  WUE and IWUE were the highest in I1.  WUE was 16.5% lower in I2 than that in I1, but yield was 26.6% higher in I2 than that in I1.  Tomato yield, WUE, and IWUE were significantly higher in N2 than that in N1 and N3.  NUE decreased with increasing N levels but NUE increased with increase the amount of water applied.  Increasing both water and N levels increased the foliar net photosynthetic rate.  I1 and I2 treatments significantly increased the contents of total soluble solids (TSS), vitamin C (VC), lycopene, soluble sugars (SS), and organic acids (OA) and the sugar:acid ratio in the fruit and decreased the nitrate content.  TSS, VC, lycopene, and SS contents were the highest in N2.  The harvest index (HI) was the highest in I2N2.  I2N2 provided the optimal combination of tomato yield, fruit quality, and WUE.  The irrigation and fertilisation regime of 75% E_p and 250 kg N ha^–1 was the best strategy of water and N management for the production of drip-irrigated greenhouse tomato.

The combined use of chemical and organic fertilizers is considered a good method to sustain high crop yield and enhance soil organic carbon (SOC), but it is still unclear when and to what extent chemical fertilizers could be replaced by organic fertilizers.  We selected a long-term soil fertility experiment in Gongzhuling, Northeast China Plain to examine the temporal dynamics of crop yield and SOC in response to chemical nitrogen, phosphorus, and potassium (NPK) fertilizers and manure, applied both individually and in combination, over the course of three decades (1980–2010).  We aimed to test 1) which fertilizer application is the best for increasing both maize yield and SOC in this region, and 2) whether chemical fertilizers can be replaced by manure to maintain high maize yield and enhance SOC, and if so, when this replacement should be implemented.  We observed that NPK fertilizers induced a considerable increase in maize yield in the first 12 years after the initiation of the experiment, but manure addition did not.  In the following years, the addition of both NPK fertilizers and manure led to an increase in maize yield.  SOC increased considerably in treatments with manure but remained the same or even declined with NPK treatments.  The increase in maize yield induced by NPK fertilizers alone declined greatly with increasing SOC, whereas the combination of NPK and manure resulted in high maize yield and a remarkable improvement in SOC stock.  Based on these results we suggested that NPK fertilizers could be at least partially replaced by manure to sustain high maize yield after SOC stock has reached 41.96 Mg C ha^–1 in the Northeast China Plain and highly recommend the combined application of chemical fertilizers and manure (i.e., 60 Mg ha^–1).

The application of nitrogen (N) fertilizer to increase crop yields has a significant influence on soil methane (CH4) and nitrous oxide (N2O) emission/uptake. A meta-analysis was carried out on the effect of N application on (i) CH4 emissions in rice paddies, (ii) CH4 uptake in upland fields and (iii) N2O emissions. The responses of CH4 emissions to N application in rice paddies were highly variable and overall no effects were found. CH4 emissions were stimulated at low N application rates (<100 kg N ha–1) but inhibited at high N rates (>200 kg N ha–1) as compared to no N fertilizer (control). The response of CH4 uptake to N application in upland fields was 15% lower than control, with a mean CH4 uptake factor of –0.001 kg CH4-C kg–1 N. The mean N2O emission factors were 1.00 and 0.94% for maize (Zea mays) and wheat (Triticum aestivum), respectively, but significantly lower for the rice (Oryza sativa) (0.51%). Compared with controls, N addition overall increased global warming potential of CH4 and N2O emissions by 78%. Our result revealed that response of CH4 emission to N input might depend on the CH4 concentration in rice paddy. The critical factors that affected CH4 uptake and N2O emission were N fertilizer application rate and the controls of CH4 uptake and N2O emission. The influences of application times, cropping systems and measurement frequency should all be considered when assessing CH4 and N2O emissions/uptake induced by N fertilizer.

    Plant height (PH) is one of the most important agronomic traits of rice, as it directly affects the lodging resistance and the high yield potential. Meanwhile, PH is often constrained by water supply over the entire growth period. In this study, a recombinant inbred line (RIL) derived from Xiaobaijingzi and Kongyu 131 strains grown under drought stress and with normal irrigation over 2 yr (2013 and 2014), respectively (regarded as four environments), was used to dissect the genetic basis of PH by developmental dynamics QTL analysis combined with QTL×environment interactions. QTLs with net effects excluding the accumulated effects were detected to explore the relationship between gene×gene interactions and gene×environment interactions in specific growth period. A total of 26 additive QTLs (A-QTLs) and 37 epistatic QTLs (E-QTLs) associated with PH were detected by unconditional and conditional mapping over seven growth periods. qPH-2-3, qPH-4-3, qPH-6-1, qPH-7-1, and qPH-12-5 could be detected by both unconditional and conditional analyses. qPH-4-3 and qPH-7-5 were detected in four stages (periods) to be sequentially expressed QTLs controlling PH continuous variation. QTLs with additive effects (A-QTLs) were mostly expressed in the period S3|S2 (the time interval from stages 2 to 3), and QTL×environment interactions performed actively in the first three stages (periods) which could be an important developmental period for rice to undergo external morphogenesis during drought stress. Several QTLs showed high adaptability for drought stress and many QTLs were closely related to the environments such as qPH-3-5, qPH-2-2 and qPH-6-1. 72.5% of the QTLs with a and aa effects detected by conditional analysis were under drought stress, and the PVE of QTLs detected by conditional analysis under drought stress were also much higher than that under normal irrigation. We infer that environments would influence the detection results and sequential expression of genes was highly influenced by environments as well. Many QTLs (qPH-1-2, qPH-3-5, qPH-4-1, qPH-2-3) coincident with previously identified drought resistance genes. The result of this study is helpful to elucidating the genetic mechanism and regulatory network underlying the development of PH in rice and providing references to marker assisted selection.

    Flixweed (Descurainia sophia L.) is a problematic and widespread weed in winter wheat fields and has been controlled by tribenuron-methyl for more than twenty years in China. In this study, a flixweed accession (Hebei 25, HB25) with an Asp-376-Glu mutation in acetohydroxy acid synthase (AHAS) was identified and purified. The purified HB25 accession (pHB25) developed 758.1-fold resistance to tribenuron-methyl and exhibited obvious cross-resistance to four AHAS-inhibiting herbicides. The resistant/susceptible (R/S) ratios of 50% plant growth reduction (GR₅₀) to herbicides of halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 346.1, 15.7, 8.1 and 7.1, respectively. The reduced AHAS sensitivities to four different AHAS-inhibiting herbicides, which were caused by the Asp-376-Glu mutation, were responsible for the resistance and cross-resistance to AHAS-inhibiting herbicides. The R/S ratios of 50% inhibition of AHAS activity (I₅₀) to tribenuron-methyl, halosulfuron-methyl, flumetsulam, imazethapyr and pyribenzoxim were 844.5, 532.9, 74.5, 13.3 and 5.5, respectively. The results of AHAS activity in vitro were highly correlated with that of whole-plant response experiments.

    Applying mathematic models to evaluate absorbed-N effects on dry matter production at different developmental stages would help determine proper nitrogen management according to crop demands and yield target. Two field trials were carried out for establishing absorbed-N effects on dry matter production (ANEDr) model, using uniform design in 2010–2011 and 2012–2013 winter wheat growing seasons in Hebei Province, China. Another field trial was carried out in 2010–2011 for model validation. Dry matter and N concentration in leaf and non-leaf organs were measured at setting, jointing, anthesis, and maturity. Theory of best linear unbiased prediction (BLUP) was applied to analyse the N effects of leaf and non-leaf organs on dry matter production. Within ANEDr model, four N-affected phases at each stage were concerned, leaf absorbed-N effect before this stage, non-leaf organ absorbed-N effect before this stage, leaf absorbed-N effect at this stage, and non-leaf organ absorbed-N effect at this stage. In addition, developmental processes, genotype characters and temperature were three factors that determine each N effect. It was demonstrated that ANEDr model can precisely quantify absorbed-N effects on dry matter production with high correlation coefficient (r=0.95). Comparing with other models, ANEDr model considered both leaf and non-leaf organs according to developmental processes of winter wheat, showed higher flexibility and simplicity, thus could be applied to different environments, cultivars and crops after parameter adjustment.

The solar radiation intensity and duration are continuously decreasing in the major wheat planting area of China. As a consequence, leaf senescence, photosynthesis, grain filling and thus wheat yield shall be affected by light deficiency. Therefore, two winter wheat (Triticum aestivum L.) cultivars, Tainong 18 (a large-spike cultivar) and Ji’nan 17 (a multiple-spike cultivar), were subjected to shading during anthesis and maturity under field condition in 2010–2011 and 2011–2012. Under the slight shading treatment (S1, 88% of full sunshine), leaf senescence was delayed, net photosynthesis rate (Pn) and canopy apparent photosynthesis rate (CAP) were improved, and thus thousand-kernel weight (TKW) and grain yield were higher as compared with the control. However, mid and severe shading (S2 and S3, 67 and 35% of full sunshine, respectively) led to negative effects on these traits substantially. Moreover, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in flag leaf were significantly greater under slight shading than those in other treatments, while the malondialdehyde (MDA) content was less than that under other treatments. In addition, the multiple-spike cultivar is more tolerant to shading than large-spike cultivar. In conclusion, slight shading after anthesis delayed leaf senescence, enhanced photosynthesis and grain filling, and thus resulted in higher grain yield.

From 1985, an increasing gap has emerged between the official statistical measures of meat production and meat consumption in China, which has raised concerns from many researchers using such data. In this paper we report the results of 428 observations (survey of 107 urban and rural households×4 quarters) from 7 provinces conducted in 2010, and compare them with the official statistical data from the National Bureau of Statistics of China (NBSC). We conclude that the main reason for the discrepancy is due to the underreporting of consumption, which is due mainly to the omission of consumption away from home.

The calculation method of potential evapotranspiration (PET) was improved by adopting a more reliable PET estimate based on the Penman-Monteith equation into the standardized precipitation evapotranspiration index (SPEI) in this study (SPEIPM). This improvement increased the applicability of SPEI in North China Plain (NCP). The historic meteorological data during 1962–2011 were used to calculate SPEIPM. The detrended yields of maize from Hebei, Henan, Shandong, Beijing, and Tianjin provinces/cities of NCP were obtained by linear sliding average method. Then regression analysis was made to study the relationships between detrended yields and SPEI values. Different time scales were applied, and thus SPEIPM was mentioned as SPEIPMk-j (k=time scale, 1, 2, 3, 4,…, 24 mon; j=month, 1, 2, 3,..., 12), among which SPEIPM3-8 reflected the water condition from June to August, a period of heavy precipitation and vigorous growth of maize in NCP. SPEIPM3-8 was highly correlated with detrended yield in this region, which can effectively evaluate the effect of drought on maize yield. Additionally, this relationship becomes more significant in recent 20 yr. The regression model based on the SPEI series explained 64.8% of the variability of the annual detrended yield in Beijing, 45.2% in Henan, 58.6% in Shandong, and 54.6% in Hebei. Moreover, when SPEIPM3-8 is in the range of –0.6 to 1.1, –0.9 to 0.8 and –0.8 to 2.3, the detrended yield increases in Shandong, Henan and Beijing. The yield increasing range was during normal water condition in Shandong and Henan, where precipitation was abundant. It indicated that the field management matched well with local water condition and thus allowed stable and high yield. Maize yield increase in these two provinces in the future can be realized by further improving water use efficiency and enhancing the stress resistance as well as yield stability. In Hebei and Beijing, the precipitation is less and thus the normal water condition cannot meet the high yield target. Increasing of water input and improving water use efficiency are both strategies for future yield increase. As global climate change became stronger and yield demands increased, the relationship between drought and maize yield became much closer in NCP too. The research of drought monitoring method and strategies for yield increase should be enhanced in the future, so as to provide strong supports for food security and agricultural sustainable development in China. Received 12

To improve the nutritional value and the palatability of air-dried rice straw, culture broth of the lactic acid bacteria community SFC-2 was used to examine the effects of two different treatments, fermentation and adsorption. Air-dried and chopped rice straw was treated with either fermentation for 30 d after adding 1.5 L nutrient solution (50 mL inocula L–1, 1.2×1012 CFU mL–1 inocula) kg–1 straw dry matter, or spraying a large amount of culture broth (1.5 L kg–1 straw dry matter, 1.5×1011 CFU mL–1 culture broth) on the straw and allowing it to adsorb for 30 min. The feed quality and aerobic stability of the resulting forage were examined. Both treatments improved the feed quality of rice straw, and adsorption was better than fermentation for preserving nutrients and improving digestibility, as evidenced by higher dry matter (DM) and crude protein (CP) concentrations, lower neutral detergent fiber (NDF), acid detergent fiber (ADF) and NH3-N concentrations, as well as higher lactic acid production and in vitro digestibility of DM (IVDMD). The aerobic stability of the adsorbed straw and the fermented straw was 392 and 480 h, respectively. After being exposed to air, chemical components and microbial community of the fermented straw were more stable than the adsorbed straw.

Infectious bursal disease virus (IBDV) is responsible for the highly contagious infectious bursal disease of chickens. Further understanding the gene-function is necessary to design the tailored vaccine. The amino acid residue 279, located on strand PF of VP2, is one of the three residues that have been reported to be involved in cell-tropism but with some inconsistency. In this study, to further clarify the amino acids involved in the cell tropism of IBDV, a series of mutations about residue 279 were introduced into the VP2 of vvIBDV Gx strain. With the reverse genetic system, we found single mutation of D279N, double mutations of D279N/A284T or Q253H/D279N were not enough to adapt IBDV to chicken embryo fibroblast (CEF) cell. To evaluate whether residue 279 could influence the replication and virulence of IBDV, the virus rGxHT-279 with three mutations (Q253H/D279N/A284T) was rescued and evaluated. Results showed that the mutation of residue 279 in VP2 had no efficient effects on both the replication efficiency in vitro and the virulence to SPF chickens of IBDV. In summary, the results demonstrated that residue 279 of VP2 did not contribute efficiently to cell tropism, replication efficiency, and virulence of IBDV at least in some strains. These findings provided further information for understanding the gene function of IBDV.

Ensuring an acceptable level of edible agro-products quality and safety is necessary to provide adequate protection for consumers. It is the first time that we analyzed the edible agro-products quality and safety issues in the supply chain, including production, processing, circulation, and consumption. The results indicate that the agro-products quality and safety levels improves steadily, and the supervision system and standardization system are both enhanced significantly, however, certain challenges still remain in each stage of the supply chain and the entire supervision process. Finally, five recommendations regarding four aspects (production, processing, circulation, and consumption) are concluded.

CB-4, a bacterial strain with highly effective herbicidal activity, was isolated from infected corn leaves. Through morphology, physiological and biochemical tests, and 16S ribosomal DNA gene sequencing methods, CB-4 was identified as Pseudomonas aeruginosa. We conducted activity-evaluation experiments in the laboratory to assess the herbicidal potential of metabolites produced by strain CB-4. Crude extracts of strain CB-4 have high inhibition activity on Digitaria sanguinalis. In general, the root and shoot growth parameters of D. sanguinalis were significantly reduced by metabolites of strain CB-4. The IC50 of the culture filtrate extracts for the radicula and coleoptile of D. sanguinalis were 0.299 and 0.210 mg mL-1, respectively. Component 2 of the herbicidal activity of the crude toxin from strain CB-4 was successfully purified for the first time by using high-speed counter current chromatography with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (4:5:4:5, v/v) and high-performance liquid chromatography. We concluded that the metabolites of strain CB-4 have the potential to be developed as a microbe-based herbicide.

MicroRNAs (miRNAs), evolutionarily conserved non-coding RNAs in length 21-24 bp, play a critical role in skeletal muscle development. In this study, to explore the function of mircoRNA-127 in porcine skeletal muscle development, eight tissue samples from adult pigs and longissimus muscle samples at 26 developmental stages were collected from Tongcheng and Landrace pigs. The spatial-temporal expression profiles of miRNA-127 were carried out using step-loop quantitative real-time PCR (stem- loop RT-PCR). To explore the molecular functions of miRNA-127, we predicted its target genes and performed functional annotation using bioinformatics methods. Results suggested that miRNA-127 was abundantly expressed in heart, ovary, uterus and spleen tissues and was weakly expressed in liver, lung, kidney and small intestine in both Tongcheng and Landrace pigs. And miRNA-127 showed significant expression differences in heart, ovary, spleen and uterus tissues between these two breeds. miRNA-127 basically kept at a relatively stable high level in middle and later embryonic stages and a low expression level in early embryonic stages and postnatal stages, but the expression levels of miRNA-127 were higher in Tongcheng pigs than in Landrace at most developmental stages. miRNA-127 potentially regulated 240 candidate genes. Results of Gene Ontology and KEGG pathway analysis indicated that these genes could be involved in many molecular functions and mechanisms, such as regulation of the force of heart contraction, regulation of transcription, regulation of T cell differentiation, MAPK signaling pathway and GnRH signaling pathway. Many significantly enriched GO terms and KEGG pathways were related to skeletal muscle development. This study will be helpful to understand the biological function for miRNA-127 and identify candidate gene associated with meat production traits in pigs.