通过2年定位试验研究不同玉米-豆科间套作模式下（玉米-大豆带状套作、玉米-花生带状间作、玉米净作、大豆净作和花生净作）作物氮素吸收与根系分布、豆科结瘤和土壤氮素有效性之间的关系。结果表明：与净作相比，间套作显著降低了单季作物的单位面积吸氮量，但玉米-大豆套作和玉米-花生间作的系统总吸氮量分别增加31.7-45.4%和7.4-12.2%。间套作显著增加了玉米和大豆的单株氮素吸收量，与净作相比分别增加61.6%和31.8%，间作花生的单株吸氮量较净作降低46.6%。间套作系统中玉米和大豆的根系呈现不对称性分布，其根长密度和根表面密度显著高于相应单作。间作花生受竞争抑制，其根表面密度显著低于相应单作。与净作相比，套作大豆的根瘤数量和根瘤鲜重显著增加，间作花生根瘤数和根瘤鲜重则显著降低。间套作显著提高了玉米和大豆的土壤酶活性（蛋白酶、脲酶、硝酸还原酶）和土壤有效氮含量，但降低了花生的土壤酶和土壤有效氮含量。玉米-大豆带状套作系统比玉米-花生带状间作系统更有利于氮素吸收，玉米与豆科间套作可以促进玉米对氮素的吸收，从而降低氮肥用量，提高农业可持续性。

连阴雨天气导致田间湿度增大，诱发田间霉菌的生长繁殖，并侵染农作物导致田间霉变的发生。在大豆生长后期，因连阴雨天气导致的田间霉变严重影响大豆的产量和品质。为探究田间霉变诱导大豆品质劣变的机制，本研究利用人工降雨室模拟连阴雨天气，诱发大豆籽粒田间霉变，结合转录组学和多种代谢检测平台，解析田间霉变胁迫下大豆品质劣变的生化机理。研究结果表明，田间霉变影响大豆的外观品质，霉变大豆籽粒皱缩、变形，并出现霉斑。田间霉变使大豆籽粒中蛋白质、多糖等储藏性物质的含量降低，导致籽粒百粒重显著下降。转录组分析发现，田间霉变使大豆籽粒中氨基酸代谢、糖酵解、三羧酸循环、脂肪酸β氧化等初生代谢过程加强。代谢组分析结果也表明，霉变大豆籽粒中多种氨基酸、糖类物质、有机酸的含量显著增加，而脂肪酸的含量则显著下降。与此同时，大豆异黄酮作为一类重要的抗逆活性物质，其生物合成在转录水平和代谢水平均受到田间霉变的诱导。田间霉变诱发大豆籽粒的防御机制，通过分解和消耗储藏性物质为防御体系的构建提供能量和底物，但储藏性物质的消耗导致了大豆品质劣变。本研究为深入了解大豆籽粒田间霉变的机制提供了重要的理论基础，同时也为抗田间霉变大豆品种的筛选指明方向。

CO₂是植物光合作用的重要原料，而气孔阻力与叶肉阻力是CO₂扩散进入叶绿体的最大限制因素。植物的气孔导度和叶肉导度对非生物胁迫因子非常敏感，这些因子通过调控羧化位点CO₂浓度来影响光合速率。气孔导度对环境的响应，叶肉导度的内部结构、生化因素限制早已有了相关综述，然而围绕环境因子对植物CO₂扩散的系统调控还未进行归纳和探讨。因此，本文综述了气孔导度和叶肉导度对非生物胁迫因子(如光强、干旱、CO₂浓度和温度)的快速响应和长期应答及其调控的生理机制，并对今后的研究趋势做了进一步展望。

在自然条件下，植物经常遭受各种生物和非生物因素胁迫而影响其生长和发育，特别是限制作物的生产能力。在影响植物光合作用的各种非生物因素中，光是驱动植物碳代谢和维持地球生命的重要因素，而光环境中光强和光质的变化极大地影响植物的光合作用以及其形态，生理和生化参数，且不同植物对光强和光质的响应不同，与其生长的环境条件有关。目前，大量研究报道了光照强度是如何影响作物的生长和发育，而本综述归纳总结了光环境中不同光质成分和光强对作物的叶片形态和解剖结构，气孔发育，光合作用，色素组成，活性氧，抗氧化酶和激素动态等相关参数的影响，旨在为作物光合作用对光强和光质的响应机制研究提供理论支撑。

Intercropping is one of the most vital practice to improve land utilization rate in China that has limited arable land resource. However, the traditional intercropping systems have many disadvantages including illogical field lay-out of crops, low economic value, and labor deficiency, which cannot balance the crop production and agricultural sustainability. In view of this, we developed a novel soybean strip intercropping model using maize as the partner, the regular maize-soybean strip intercropping mainly popularized in northern China and maize-soybean relay-strip intercropping principally extended in southwestern China. Compared to the traditional maize-soybean intercropping systems, the main innovation of field lay-out style in our present intercropping systems is that the distance of two adjacent maize rows are shrunk as a narrow strip, and a strip called wide strip between two adjacent narrow strips is expanded reserving for the growth of two or three rows of soybean plants.  The distance between outer rows of maize and soybean strips are expanded enough for light use efficiency improvement and tractors working in the soybean strips.  Importantly, optimal cultivar screening and increase of plant density achieved a high yield of both the two crops in the intercropping systems and increased land equivalent ratio as high as 2.2.  Annually alternative rotation of the adjacent maize- and soybean-strips increased the grain yield of next seasonal maize, improved the absorption of nitrogen, phosphorus, and potasium of maize, while prevented the continuous cropping obstacles.  Extra soybean production was obtained without affecting maize yield in our strip intercropping systems, which balanced the high crop production and agricultural sustainability.

In China, the abuse of chemical nitrogen (N) fertilizer results in decreasing N use efficiency (NUE), wasting resources and causing serious environmental problems.  Cereal-legume intercropping is widely used to enhance crop yield and improve resource use efficiency, especially in Southwest China.  To optimize N utilization and increase grain yield, we conducted a two-year field experiment with single-factor randomized block designs of a maize-soybean intercropping system (IMS).  Three N rates, NN (no nitrogen application), LN (lower N application: 270 kg N ha^–1), and CN (conventional N application: 330 kg N ha^–1), and three topdressing distances of LN (LND), e.g., 15 cm (LND1), 30 cm (LND2) and 45 cm (LND3) from maize rows were evaluated.  At the beginning seed stage (R5), the leghemoglobin content and nitrogenase activity of LND3 were 1.86 mg plant^–1 and 0.14 mL h^–1 plant^–1, and those of LND1 and LND2 were increased by 31.4 and 24.5%, 6.4 and 32.9% compared with LND3, respectively.  The ureide content and N accumulation of soybean organs in LND1 and LND2 were higher than those of LND3.  The N uptake, NUE and N agronomy efficiency (NAE) of IMS under CN were 308.3 kg ha^–1, 28.5%, and 5.7 kg grain kg^–1 N, respectively; however, those of LN were significantly increased by 12.4, 72.5, and 51.6% compared with CN, respectively.  The total yield in LND1 and LND2 was increased by 12.3 and 8.3% compared with CN, respectively.  Those results suggested that LN with distances of 15–30 cm from the topdressing strip to the maize row was optimal in maize-soybean intercropping.  Lower N input with an optimized fertilization location for IMS increased N fixation and N use efficiency without decreasing grain yield.

    Bovine mastitis caused by Staphylococcus aureus is difficult to treat because of increasing resistance against antibiotics, especially penicillin. β-Lactamase and biofilm are responsible for penicillin resistance of S. aureus. The aim of this study was to investigate the β-lactamase activity and biofilm formation capacity of 37 penicillin-resistant S. aureus strains (35 were blaZ positive and 2 were blaZ negative) from bovine mastitis in Gansu Province, China, as well as to measure the intercellular adhesion genes icaA and icaD of these strains. β-Lactamase Test Kit was used to determine the β-lactamase activity, biofilm formation was tested by semi-quantitative adherence assay method. Moreover, the presence of icaA and icaD were measured by PCR. A total of 32 penicillin-resistant S. aureus strains, including the two blaZ-negative strains, were identified as β-lactamase producers. All tested S. aureus isolates produced biofilm in the microtiter plate assay. Meanwhile, all these strains were PCR-positive for the ica locus, icaA and icaD. The study indicated high prevalence of β-lactamase activity, biofilm-forming capacity, and the ica genes among the penicillin-resistant S. aureus isolates, and implied that S. aureus resistant to penicillin was attributed to multiple mechanisms.

Soybean is one of the major oil seed crops, which is usually intercropped with other crops to increase soybean production area and yield.  However, soybean is highly sensitive to shading.  It is unclear if soybean morphology responds to shading (i.e., shade tolerance or avoidance) and which features may be suitable as screening materials in relay strip intercropping.  Therefore, in this study, various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.  The soybean materials used in this study exhibited genetic diversity, and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08% during the shade period and from 6.44 to 52.49% during the maturity period.  The ratios of shading to full irradiance in stem mass fraction (SMF) were almost greater than 1, whereas opposite results were found in the leaves.  Compared with full irradiance, the average stem length (SL), leaf area ratio (LAR) and specific leaf area (SLA) for the two years (2013 and 2014) increased by 0.78, 0.47 and 0.65 under shady conditions, respectively.  However, the stem diameter (SD), total biomass (TB), leaf area (LA), number of nodes (NN) on the main stem, and number of branches (BN) all decreased.  During the shady period, the SL and SMF exhibited a significant negative correlation with yield, and the SD exhibited a significant positive correlation with yield.  The correlation between the soybean yield and agronomic parameters during the mature period, except for SL, the first pod height (FPH), 100-seed weight (100-SW), and reproductive growth period (RGP), were significant (P<0.01), especially for seed weight per branch (SWB), pods per plant (PP), BN, and vegetative growth period (VGP).  These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.  

  Herbicidal residues of imazamox are hazardous to some sensitive rotational aftercrops. The aim of the study was to isolate and identify a microbial strain capable of degrading imazamox. The strain IB5, capable of efficiently degrading imazamox, was isolated from an imazamox-contaminated soybean field in Heilongjiang Province, China. It was found to degrade 98.61% of 400 mg L^–1 imazamox within 48 h by high-performance liquid chromatograph. Through morphological, physiological and biochemical characterization, and the 16S rDNA sequencing, the strain was identified as Acinetobacter baumannii. An optimal degradation condition was obtained and verified: 400 mg L^–1 imazamox, 0.1% (volume ratio) initial inoculum, 37°C and pH 7.0. Four main products were captured in the liquid chromatograms and mass spectra, and a pathway for imazamox degradation by IB5 was proposed. This work provides a new suitable candidate for imazamox biodegradation and theoretical evidence for imazamox residue bioremediation. A. baumannii is a common clinical bacteria, but its imazamox-degrading feature has not been reported previously.

    Staphylococcus aureus is the most common etiological pathogen of bovine mastitis. The resistant strains make the disease difficult to cure. The aim of this study was to characterize the genetic nature of the antimicrobial resistance in S. aureus cultured from bovine mastitis in Northwest China in 2014. A total of 44 S. aureus were isolated for antimicrobial resistance and resistance-related genes. Antimicrobial resistance was determined by disc diffusion and the corresponding resistance genes were detected by PCR. Phenotype indicated that S. aureus isolates were resistant to penicillin (84.09%), erythromycin (20.45%), tetracycline (15.91%), gentamicin (9.09%), tobramycin (6.82%), kanamycin (6.82%) and methicillin (2.27%). 9.09% of the S. aureus isolates were classified as multidrug resistant. In addition, genotypes showed that the isolates were resistant to rifampicin (100%, rpoB), penicillin (95.45%, blaZ), tetracycline (22.73%, tetK, tetM, alone or in combination), erythromycin (22.73%, ermB or ermC), gentamicin/tobramycin/kanamycin (2.27%, aacA-aphD), methicillin (2.27%, mecA) and vancomycin (2.27%, vanA). Resistance to tetracycline was attributed to the genes tetK and tetM (r=0.558, P<0.001). This study noted high-level geno- and phenotypic antimicrobial resistance in S. aureus isolates from bovine mastitis cases in Northwest China.

The bsd-pg (bundle sheath defective pale green) mutant is a novel maize mutation, controlled by a single recessive gene, which was isolated from offspring of maize plantlets regenerated from tissue callus of the maize inbred line 501. The characterization was that the biogenesis and development of the chloroplasts was mainly interfered in bundle sheath cells rather than in mesophyll cells. For mapping the bsd-pg, an F2 population was derived from a cross between the mutant bsd-pg and an inbred line Xianzao 17. Using specific locus amplified fragment sequencing (SLAF-Seq) technology, a total of 5 783 polymorphic SLAFs were analysed with 1 771 homozygous alleles between maternal and paternal parents. There were 49 SLAFs, which had a ratio of paternal to maternal alleles of 2:1 in bulked normal lines, and three trait-related candidate regions were obtained on chromosome 1 with a size of 3.945 Mb. For the fine mapping, new simple sequence repeats (SSRs) markers were designed by utilizing information of the B73 genome and the candidate regions were localized a size of 850 934 bp on chromosome 1 between umc1603 and umc1395, including 35 candidate genes. These results provide a foundation for the cloning of bsd-pg by map-based strategy, which is essential for revealing the functional differentiation and coordination of the two cell types, and helps to elucidate a comprehensive understanding of the C4 photosynthesis pathway and related processes in maize leaves.

In the present experiment, effects of sodium hydrosulfide (NaHS), a H2S donor, on the oxidative damage, antioxidant capacity and the growth of cucumber hypocotyls and radicles were studied under 100 mmol L-1 NaCl stress. NaCl treatment significantly induced accumulation of H2O2 and thiobarbituric acid-reactive substances (TBARS) in cucumber hypocotyls and radicles, and application of NaHS dramatically reduced the accumulation of H2O2 and lipid peroxidation. However, the alleviating effects greatly depended on the concentrations of NaHS, and 400 μmol L-1 NaHS treatment showed the most significant effects. Corresponding to the change of lipid peroxidation, higher activities of antioxidant enzymes as well as the antioxidant capacity indicated as DPPH scavenging activity, chelating activity of ferrous ions and hydroxyl radical (·OH) scavenging activity were induced by NaHS treatment under NaCl stress, especially by 400 μmol L-1 NaHS treatment. With the alleviating lipid peroxidation, the amylase activities in cotyledons were increased, and the length of cucumber hypocotyls and radicles were significantly promoted by NaHS treatment under NaCl stress. Unlike the effects of NaHS, pretreatment with other sodium salts including Na2S, Na2SO4, NaHSO4, Na2SO3, NaHSO3 and NaAc did not show significant effects on the growth of cucumber hypocotyls and radicles. These salts do not release H2S. Based on above results, it can be concluded that the effects of NaHS in the experiment depended on the H2S rather than other compounds derived from NaHS, and the alleviating effects might related with its function in modulating antioxidant capacity and amylase activities.

Phytophthora sojae Kanfman and Gerdemann (P. sojae) is one of the most prevalent pathogens and causes Phytophthora root rot, which limits soybean production worldwide. Development of resistant cultivars is a cost-effective approach to controlling this disease. In this study, 127 soybean germplasm were evaluated for their responses to Phytophthora sojae strain Pm28 using the hypocotyl inoculation technique, and 49 were found resistant to the strain. The hypocotyl of P1, P2, F1, and F2:3 of two crosses of Ludou 4 (resistant)×Youchu 4 (susceptible) and Cangdou 5 (resistant)×Williams (susceptible) were inoculated with Pm28, and were used to analyze the inheritance of resistance. The population derived from the cross of Ludou 4×Youchu 4 was used to map the resistance gene (designated as Rps9) to a linkage group. 932 pairs of SSR primers were used to detect polymorphism, and seven SSR markers were mapped near the resistance gene. The results showed that the resistance to Pm28 in Ludou 4 and Cangdou 5 was controlled by a single dominant gene Rps9, which was located on the molecular linkage group N between the SSR markers Satt631 (7.5 cM) and Sat_186 (4.3 cM).