有机物料输入对干润砂质新成土可溶性有机碳、氮的影响

对采集于干润砂质新成土不同土层土壤分别添加高C/N（黑麦草）和低C/N（苜蓿）有机物料后进行了室内培养试验。结果表明,各土层土壤添加有机物料后,均存在不同程度的矿质氮微生物净固定现象,且氮固定时间及程度与有机物料的C/N和土壤层次密切相关,添加高C/N黑麦草的深层低肥力土壤氮固定现象最明显。添加有机物料后,培养期间可溶性有机碳（DOC）累积量前期较高,中期先减后增,后期趋于稳定,不同土层土壤DOC的变化有所不同。0～20、20～40cm可溶性有机氮（DON）累积同时受矿质氮固定影响,低C/N苜蓿残体加入土壤后,在短暂氮素固定后,后期DON累积量明显提高;而加入高C/N黑麦草残体后,在较长时间内DON累积量无明显增加。添加有机物料导致培养前期土壤DOC/DON上升,随后降低。以上研究结果表明,如果从增加干润砂质新成土土壤有机质角度考虑,应该种植高C/N比的植物。因此,研究有利于进一步深入理解土壤溶液速效C、N养分的来源及其转化,对该地区土壤质量的调控具有一定参考价值。     

Dissolved organic carbon and nitrogen in precipitation, throughfall and stemflow fromSchima superba andCunninghamia lanceolata plantations in subtropical China

Despite growing attention to the role of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in forest nutrient cycling, their monthly concentration dynamics in forest ecosystems, especially in subtropical forests only were little known. The goal of this study is to measure the concentrations and monthly dynamics of DOC and DON in precipitation, throughfall and stemflow for two plantations ofSchima superba (SS) and Chinese fir (Cunninghamia lanceolata, CF) in Jianou, Fujian, China. Samples of precipitation, throughfall and stemflow were collected on a rain event base from January 2002 to December 2002. Upon collection, all water samples were analyzed for DOC, NO₃ ⁻−N, NH₄ ⁺−N and total dissolved N (TDN). DON was calculated by subtracting NO₃ ⁻−N and NH₄ ⁺−N from TDN. The results showed that the precipitation had a mean DOC concentration of 1.7 mg·L⁻¹ and DON concentration of 0.13 mg·L⁻¹. The mean DOC and DON concentrations in throughfall were 11.2 and 0.24 mg·L⁻¹ in the SS and 10.3 and 0.19 mg·L⁻¹ in the CF respectively. Stemflow DOC and DON concentrations in the CF (19.1 and 0.66 mg·L⁻¹ respectively) were significantly higher than those in the SS (17.6 and 0.48 mg·L⁻¹ respectively). No clear monthly variation in precipitation DOC concentration was found in our study, while DON concentration in precipitation tended to be higher in summer or autumn. The monthly variations of DON concentrations were very similar in throughfall and stemflow at both forests, showing an increase at the beginning of the rainy season in March. In contrast, monthly changes of the DOC concentrations in throughfall of the SS and CF were different to those in stemflow. Throughfall DOC concentrations were higher from February to April, while relatively higher DOC concentrations in stemflow were found during September–November period. Foundation item: This study was supported by the Teaching and Research Award program for MOE P.R.C. (TRAPOYT). Biography: Guo Jian-fen (1977-), female, Ph. Doctor in College of Life Science, Xiamen University, Xiamen 361005, P.R. China. Responsible editor: Zhu Hong     

In situ carbon and nitrogen dynamics in ryegrass-clover mixtures: Transfers, deposition and leaching

Carbon (C) and nitrogen (N) dynamics in a third production year ryegrass-clover mixture were investigated in the field. Cylinders (diameter 29.7 cm) were installed to depths of 20, 40 and 60 cm and equipped with suction cups to collect percolating pore water. Ryegrass and clover leaves were cross-labelled with ¹⁴C- and ¹⁵N-enriched urea and the fate of the two tracers was studied for 3 months during summer. Transfer of ¹⁴C occurred mainly from ryegrass to clover, whereas the largest transfer of ¹⁵N was in the opposite direction. The average transfer of N from clover was 40% (SE±3.1, n=9) of N in ryegrass, whereas the fraction of N in clover donated by ryegrass was 5% (±1.2, n=9). The amount of ¹⁴C transferred from ryegrass to clover was 1.7% (±0.1, n=9) of the ¹⁴C-activity in the total above-ground plant biomass found in the unlabelled clover and with a transfer from clover to ryegrass being 0.4% (±0.1, n=9). ¹⁵N-enriched compounds were not detected in percolating pore water, which may be caused by either dilution from irrigation or low availability of leachable N compounds. ¹⁴C was found solely as ¹⁴CO₂ in the pore water indicating that dissolved organic carbon (DOC) did not originate from fresh root deposits. Transfer of ¹⁴C between the two species in the mixed crop alongside with high transfer of ¹⁵N despite a large percolation of pore water indicates that part of the N transfer occurred in non-leachable N-forms. The amount of N transferred between the two species was found to depend on the ratio between dry matter accumulated in the donating and receiving species, the ¹⁴C-allocation within the receiving species and the root turnover rate in the soil.     

Dissolved soil organic matter from surface organic horizons under birch and conifers: Degradation in relation to chemical characteristics

The degradability and chemical characteristics of dissolved organic carbon (DOC) and nitrogen (DON) from the litter, F and H layers of silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.) stands were studied in an incubation experiment. Soil dissolved organic matter (DOM) was collected by centrifugation. Degradability was assessed in an incubation experiment by measuring the loss of DOC and DON, the mineralization rate of DOC and the availability of DOM to both bacteria and fungi, and by estimating the proportion of labile DOC of the total DOC. The degradability of DOC was highest in the litter layer and in that layer under birch. In the F and H layers, however, the degradability was highest under spruce. The most degradable fractions were the hydrophilic neutral fraction of DOC, the hydrophilic base fraction of DON, and the phenol fraction, as well as the smallest (<1 kDa) and largest (>100 kDa) molecular size classes of both DOC and DON. The degradability of these fractions seemed to be related to their relatively low C-to-N ratios. The hydrophilic acid fraction and the molecular size class of 1-10 kDa were more abundant in the H layer than in the litter layer, and thus apparently indicating a more decomposed DOM. In general, the effect of tree species on DOM was more obvious in the litter layer than in the lower organic layers.     

六棱大麦抗赤霉病QTL的定位(英文)

赤霉病是最严重的大麦病害之一。由于赤霉病抗性是受多基因控制的数量性状(QTL),并且一些表型性状也影响大麦赤霉病的抗病,如棱数、株高和抽穗期等,所以抗赤霉病大麦品种的选育十分困难。为了明确加拿大六棱大麦中赤霉病抗性以及相关性状的QTLs,本研究在4年中对93个家系的DH作图群体中赤霉病抗性、呕吐毒素(DON)含量、株高、抽穗期和成熟期等相关性状进行调查,并利用分子标记(444个DArT和26个SSR标记)构建的连锁图谱对QTL开展复合区间作图。结果表明,本研究共检测到4个影响赤霉病的QTLs,其中,2个主要的QTLs定位在3H和7H染色体上,它们的加性效应为-3.44和-3.69,分别解释14.1%和17.5%的表型差异,总共解释31.6%的赤霉病抗性差异;另外2个QTLs定位于7H染色体上,但二者同时也与DON含量显著相关。此外,在3H、5H和7H染色体上确定了5个影响株高的QTLs,在2H、4H、5H和7H上确定了4个影响抽穗期的QTLs。同时发现2个赤霉病抗性QTLs和1个DON累积QTL与控制株高的QTLs聚集重叠,1个赤霉病抗性QTL和抽穗期QTLs重叠。这些与赤霉病抗性、株高及抽穗期等农艺性状紧密连锁的分子标记可进一步用于有效提高抗赤霉病大麦品种的选育效率。     

小麦中镰刀菌毒素脱氧雪腐镰刀菌烯醇污染现状与防控研究进展

脱氧雪腐镰刀菌烯醇（DON）,又称呕吐毒素,是由小麦赤霉病菌禾谷镰刀菌复合群（Fusarium graminearum species complex）产生的单端孢霉烯族毒素,毒素在小麦籽粒中累积。作为B型单端孢霉烯族毒素,DON可以引起呕吐、拒食、腹泻、出血甚至死亡, 对猪的危害尤其严重。近年来,小麦赤霉病在世界各地高频率流行,尤其在中国长江中下游小麦生产区以及黄淮部分小麦产区、美国中西部小麦主产区,导致小麦中DON毒素严重超标,并引发了严重的食品安全问题。本文对国内外小麦中DON毒素的污染现状、产毒镰刀菌种类及其化学型的分布及其趋势、毒素产生的调控机制以及小麦中DON毒素的防控途径进行了论述,希望有助于镰刀菌毒素污染小麦质量安全的风险评估、监管以及科学处置。     

多菌灵及其复配制剂防治小麦赤霉病的应用效果

为测定在小麦赤霉病菌Fusarium graminearum抗性频率上升的条件下多菌灵及其复配制剂对小麦赤霉病的防效,于2014—2016年监测了江苏省南通市同块试验田中小麦赤霉病菌对多菌灵的抗药性,并进行了田间药效试验。结果表明,2014、2015和2016年小麦赤霉病菌对多菌灵的抗性频率分别为22.97%、38.55%和43.38%,呈逐年上升趋势。2016年戊唑醇及复配剂多菌灵·戊唑醇、多菌灵·三唑酮处理对小麦赤霉病的田间防效分别达97.82%、92.16%、85.98%,增产效果分别达23.90%、23.54%、22.57%;小麦样品(混粒)中DON毒素含量分别比空白对照降低57.39%、59.99%、43.34%,均优于多菌灵单剂处理,其中以戊唑醇及复配剂多菌灵·戊唑醇处理最好,多菌灵·三唑酮处理次之。因此,在抗性程度中等或偏轻的地区,采用戊唑醇、复配剂多菌灵·戊唑醇防治小麦赤霉病可取得较好的防病、增产及降低DON毒素的效果。     

链霉菌抗生物素蛋白—过氧化物酶连结法定位肝脏中脱氧雪腐镰刀菌烯醇的研究

脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON),又名呕吐毒素,是目前全球谷物污染最严重的真菌毒素之一。在所有的易感动物中,以猪最为敏感。本研究选用10头健康阉公猪,随机分为2组,染毒组和对照组,染毒组经乳静脉注射DON,注射剂量为75μg/kg体重,对照组经乳静脉注射生理盐水。注射完成后开始计时30 min后放血宰杀,迅速取肝脏,采用链霉菌抗生物素蛋白—过氧化物酶连接结(streptavidin-perosidase,SP)法定位肝组织中的DON。SP法定位结果显示,在染毒组肝门管区小叶间静脉的血管壁有DON的分布。本研究采用SP法定位DON在猪体内消化器官组织的分布情况,为毒素的残留研究提供依据。     

春季解冻过程对2种温带森林土壤微生物量碳氮和可溶性有机碳氮的影响

为了研究春季土壤冻融过程对碳氮周转的影响,以长白山地区2种森林土壤为研究对象,利用原位培养连续取样法,测定和分析了土壤微生物量碳(MC)、氮(MN)和可溶性有机碳(DOC)、氮(DON)在春季解冻期间的含量动态变化。结果表明:土壤解冻过程中,2种林型土壤微生物量碳、氮的时间变化动态不同,且土壤微生物量碳、氮表现出明显的垂直空间异质性,0—10cm土层土壤微生物量氮显著高于10—20cm土层。除个别时期外,0—10cm土层土壤微生物量碳亦显著高于10—20cm土层土壤。解冻过程中,2种林型0—10cm土层土壤DOC含量时间变化动态基本一致,而红松阔叶林10—20cm土层土壤最大DOC释放量早于次生白桦林。2种林型DOC释放过程集中于解冻中后期。解冻期2种林型土壤DON时间变化动态表现一致,最大土壤DON释放量出现在解冻中后期。解冻期2种林型土壤DON存在明显的垂直空间分布特征,0—10cm土层土壤DON含量显著高于10—20cm土层。     

DON、ZEA联合染毒对体外培养鸡脾脏淋巴细胞分泌IL-2、IL-4、IL-10和IFN-γ的影响

旨在研究DON、ZEA联合染毒对体外培养鸡脾脏淋巴细胞分泌IL-2、IL-4、IL-10和IFN-γ的影响。DON、ZEA联合染毒剂量为0.012 5 μg·mL^-1和0.006 25 μg·mL^-1、0.050 μg·mL^-1和0.025 μg·mL^-1、0.2 μg·mL^-1和0.1 μg·mL^-1、0.8 μg·mL^-1和0.4 μg·mL^-1,进行DON、ZEA联合染毒48 h对鸡脾脏淋巴细胞上清液IL-2、IL-4、IL-10和IFN-γ含量及其mRNA表达的影响。结果表明,各染毒组细胞上清液IL-10和IFN-γ蛋白含量,细胞内IL-2、IL-4和 IL-10 mRNA水平随毒素剂量的升高而增加 (P<0.01);各染毒组细胞上清液IL-2和IL-4蛋白含量均随毒素浓度的升高而降低(P<0.01);细胞内IFN-γ mRNA表达量均随毒素浓度的升高而先升高后降低(P<0.01)。DON、ZEA联合染毒导致细胞因子IL-2、IL-4、IL-10和IFN-γ分泌失衡,且呈剂量依赖性;DON、ZEA联合染毒鸡脾淋巴细胞上调或下降促炎性细胞因子的水平; Th1和Th2细胞因子平衡失调,因此造成细胞免疫损伤,从而对细胞产生毒性。