Novel Field Data on Phytoextraction: Pre-Cultivation With Salix Reduces Cadmium in Wheat Grains

Cadmium (Cd) is a health hazard, and up to 43% of human Cd intake comes from wheat products, since Cd accumulates in wheat grains. Salix spp. are high-accumulators of Cd and is suggested for Cd phytoextraction from agricultural soils. We demonstrate, in field, that Salix viminalis can remove Cd from agricultural soils and thereby reduce Cd accumulation in grains of wheat subsequently grown in a Salix-treated field. Four years of Salix cultivation reduce Cd concentration in the soil by up to 27% and in grains of the post-cultivated wheat by up to 33%. The higher the plant density of the Salix, the greater the Cd removal from the soil and the lower the Cd concentration in the grains of post-cultivated wheat, the Cd reduction remaining stable several years after Salix cultivation. The effect occurred in both sandy and clayey soil and in winter and spring bread wheat cultivars. Already one year of Salix cultivation significantly decrease Cd in post grown wheat grains. With this field experiment we have demonstrated that phytoextraction can reduce accumulation of a pollutant in post-cultivated wheat and that phytoextraction has no other observed effect on post-cultivated crops than reduced uptake of the removed pollutant.     

外源脱落酸对小麦幼苗抗镉胁迫能力的影响

以小麦(Triticum aestivum L.)为试材,采用水培法研究了100mg/L镉(Cd2+)胁迫条件下施用外源脱落酸(ABA)对小麦幼苗生长及某些生理生化指标的影响。结果表明:(1)100mg/L Cd2+胁迫下,小麦叶片膜脂过氧化产物丙二醛(MDA)含量显著提高,植株生长受到抑制;(2)外源ABA能够明显提高Cd2+胁迫小麦幼苗的根系活力,增加其叶片SOD、CAT和POD活性,促进其脯氨酸积累,降低MDA的含量,并以5.0μmol/L ABA的效果最明显;(3)1.0～5.0μmol/L外源ABA不同程度地缓解Cd2+胁迫对小麦幼苗生长的抑制作用,且5.0μmol/L时效果最明显,其株高、根长、总干重分别比单一Cd2+胁迫处理显著提高6.73%、149%和10.52%,而10.0μmol/LABA反而加重了Cd2+对小麦幼苗生长的伤害。因此,适宜浓度的外源ABA能够通过增加体内保护酶活性和脯氨酸含量来缓解Cd2+胁迫对小麦幼苗生长的抑制作用,增强小麦幼苗的抗Cd2+胁迫能力,并以5.0μmol/L ABA处理效果最好。     

Spatial Variability in Species Composition in Birds and Insects

If spatial patterns of change within a habitat were similar for both vertebrates and insects, then vertebrates would provide useful surrogates for designing reserves for the conservation of invertebrates. Data from two eucalypt habitats were analysed to determine levels of habitat richness, site richness and species turnover in birds and insects. For birds the relatively low species richness and turnover indicated that sites within the habitat were similar in composition. In wet eucalypt forests Diptera were very speciose with over 1,000 morphospecies sorted. Species turnover was slightly higher than for birds, indicating a large number of species change from site to site. In dry eucalypt woodland, insects trapped through the winter months were not speciose but turnover between sites was very large. This suggests reserves designed to conserve insects may need to be larger than for birds in order to include the high site variability and richness of insect communities.Spatial patterns of birds and insects were investigated further, to determine if sites that were closer together were more similar for both birds and insects. No patterns were found for birds in either habitat suggesting birds are not responding to changes in the environment at this scale. Diptera in wet eucalypt forest showed higher similarity between close sites than distant sites, while for winter insects in dry eucalypt woodland the relationship was significant when two outlier points were removed. Overall, birds are not good surrogates for insects in either habitat as no relationship between birds and insects in site-to-site similarity was found.     

He-Ne激光预处理对镉胁迫下小麦幼苗生理特性的影响

用He-Ne激光（波长632.8 nm,辐射剂量5.43 mW/mm²）对萌动小麦种子辐照5 min,待幼苗长至一叶一心时,用150 μmol/L CdCl₂溶液进行胁迫处理,研究He-Ne激光预处理对镉（Cd²⁺）胁迫下小麦幼苗生长发育和生理特性的影响。结果显示:He-Ne激光预处理能显著降低Cd²⁺胁迫下小麦幼苗中丙二醛（MDA）、过氧化氢（H₂O₂）含量及超氧自由基（O^-·₂）产生速率,显著提高幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸氧化酶（APX）活性,并使叶片抗氧化物质谷胱甘肽(GSH)和抗坏血酸(AsA)含量以及幼苗株高、根长和干重增加。研究表明,He-Ne激光预处理可有效缓解镉胁迫对小麦幼苗生长的抑制作用,并通过促进其幼苗中酶类和非酶类抗氧化剂的产生,有效减少镉胁迫产生的脂质过氧化物含量,从而提高其耐镉性。     

城市污泥堆肥温度的空间变异性研究

利用半变异函数对城市污泥堆肥温度的空间变异特性进行了研究 ,对堆体温度进行了克里格法 ( KRIGING)插值。采用通风静态垛堆肥工艺 ,试验了 0 .79、2 .0 3m3 / ( min·m3 )两种通风量。沿着堆肥池长度方向设定 2个纵剖面 ,每个纵剖面的面积为 6 .0 m× 1 .0 m,按 0 .5 m× 0 .1 m布设网格。结果表明 ,在水平方向上堆肥温度的半变异函数用球状模型进行拟合效果较好 ,而在垂直方向上的半变异函数用线性模型进行拟合效果较好 ;在水平方向上两个剖面的温度变程 ( range)分别为 0 .90 m、1 .2 5 m,在垂直方向上的变程分别为 0 .75 m、1 .0 0 m;利用克里格法进行最优内插估值得到的温度等值线图表明 ,高温区域一般位于堆体中层 0 .4～ 0 .6 m,低温区域一般位于堆体下层 0～ 0 .4 m;从温度剖面等值线图判断 ,中试规模的城市污泥堆肥 ,其合理通风量小于 0 .79m3 / min· m3 。     

大豆籽粒镉积累QTL的整合及其分子标记的验证

该研究在收集大豆籽粒镉积累定位信息的基础上,通过参考图谱分子标记比较整合已有的定位信息,进一步在‘中黄24’(籽粒高积累镉)与‘华夏3号’(籽粒低积累镉)衍生的(F6:7)重组自交系群体中,对大豆籽粒镉积累的QTL位点及其分子标记进行验证。结果表明,在不同群体中定位的籽粒镉积累2个主效QTL(Cda1和Cd1)位于第9染色体同一区域;该区段内候选基因GmHMA1的点突变,在籽粒镉积累不同的‘中黄24’和‘华夏3号’之间是一致的;该位点与‘中黄24’和‘华夏3号’各器官的镉浓度并无连锁关系。研究认为,‘中黄24’与‘华夏3号’间籽粒镉积累差异由其它位点控制,需要利用该重组自交系群体进行全基因组定位。     

麦蚜自然种群的空间动态

一、引言在生态学中研究种群动态有两个分支,一是追踪数量随时间变化,既所谓数量动态的问题,另一是考查种群个体在空间散布状态的变化,即所谓空间动态的问题。关于空间动态中分布型的研究过去多采用传统的块面调查,用     

黄淮海冲积平原区土壤有机质时空变异特征

通过分析124个样点1980年和2000年耕层土壤的有机质含量,研究了黄淮海冲积平原区河北省曲周县土壤有机质的时空变异特征,研究结果表明,该县目前土训有机质含量平均为12.89g/kg。与1980年相比较增加了4.11g/kg,年均增加0.21g/kg。但因各农户施用有机肥量的不同和管理水平的差异。占全县耕地面积6%的土壤有机质含量不升反降,县内各区域有机质的增长趋势为西南部和东南部高于中部和北部,潮上,盐土和褐土2000年有机质含量分别比1980年增加45.51%,82.48%和68.57%。     

小麦腺苷二磷酸葡萄糖焦磷酸化酶同工酶类型及时空表达分析

以9个小麦品种为材料,采用非变性聚丙烯酰胺凝胶电泳(Native-PAGE)和SDS聚丙烯酰胺凝胶电泳(SDS-PAGE)鉴定ADP-葡萄糖焦磷酸化酶(AGP)同工酶类型、表达数量及亚基组成,分析AGP同工酶空间分布特点和器官表达特异性。结果表明:(1)小麦植株中共表达6种AGP同工酶,即AGPp、AGPs、AGPe1、AGPe2、AGPe3和AGPe4。(2)AGPp分布在种皮中,AGPs分布在种皮与叶片中,而AGPe1、AGPe2、AGPe3和AGPe4专一在胚乳中表达;在小麦籽粒灌浆过程中,AGPe1首先表达,AGPe2和AGPe3紧随其后,AGPe4最后表达。(3)AGP各同工酶均由大、小2个亚基组成,小亚基分子量为50kD左右,大亚基分子量在51~54kD之间。(4)AGP同工酶空间分布具有器官特异性,并在籽粒发育进程中顺序表达;AGPe3、AGPe1和AGPe2是占主导地位的AGP同工酶,且可能是决定AGP总酶活性的主效应酶,在灌浆后期籽粒淀粉合成中起关键作用。     

Spatial Variability of Soil Properties in the Shortgrass Steppe: The Relative Importance of Topography, Grazing, Microsite, and Plant Species in Controlling Spatial Patterns

We conducted a study to evaluate the relative importance of topography, grazing, the location of individual plants (microsite), and plant species in controlling the spatial variability of soil organic matter in shortgrass steppe ecosystems. We found that the largest spatial variation occurs in concert with topography and with microsite-scale heterogeneity, with relatively little spatial variability due to grazing or to plant species. Total soil C and N, coarse and fine particulate organic matter C and N, and potentially mineralizable C were significantly affected by topography, with higher levels in toeslope positions than in midslopes or summits. Soils beneath individual plants (Bouteloua gracilis and Opuntia polyacantha) were elevated by 2–3 cm relative to surrounding soils. All pools of soil organic matter were significantly higher in the raised hummocks directly beneath plants than in the soil surface of interspaces or this layer under plants. High levels of mineral material in the hummocks suggest that erosion is an important process in their formation, perhaps in addition to biotic accumulation of litter beneath individual plants. Over 50 y of heavy grazing by cattle did not have a significant effect on most of the soil organic matter pools we studied. This result was consistent with our hypothesis that this system, with its strong dominance of belowground organic matter, is minimally influenced by aboveground herbivory. In addition, soils beneath two of the important plant species of the shortgrass steppe, B. gracilis and O. polyacantha, differed little from one another. The processes that create spatial variability in shortgrass steppe ecosystems do not affect all soil organic matter pools equally. Topographic variability, developing over pedogenic time scales (centuries to thousands of years), has the largest effect on the most stable pools of soil organic matter. The influence of microsite is most evident in the pools of organic matter that turn over at time scales that approximate the life span of individual plants (years to decades and centuries).     

铜、镉胁迫下施硫肥和有机肥对冬小麦碳氮运转的影响

采用盆栽试验,研究了铜、镉胁迫条件下施硫和有机肥对冬小麦碳氮运转的影响。结果表明,与各自对照相比,铜、镉胁迫下低施硫和有机肥的处理增加了小麦叶片、茎鞘、颖壳穗轴等营养器官花前贮藏物质、氮素的再运转量和运转率以及营养器官花前贮藏物质、氮素的总再运转量和总运转率,高施硫和有机肥的铜、镉处理则规律性不明显。在铜、镉胁迫条件下,施用硫肥和有机肥处理增加了小麦成熟期籽粒重和花后光合同化物输入籽粒量以及籽粒氮素含量和花后氮素积累量。与各自对照相比,铜胁迫下施硫和有机肥的处理与镉胁迫下低施硫和有机肥的处理增加了成熟期小麦的穗数、穗粒数和千粒重,提高了籽粒产量,其中以T\-5处理增产幅度最大;镉胁迫下高施硫和有机肥的处理则变化不大。铜、镉胁迫下低施硫和有机肥的处理均增加了籽粒淀粉含量,而高施硫和有机肥的铜、镉处理则未表现出此规律。此外,铜、镉胁迫下施硫和有机肥的各处理增加了籽粒蛋白质的含量。     

水肥空间组合对成熟期冬小麦各器官氮磷养分分配的影响

以肥熟土垫旱耕人为土为供试土壤,冬小麦(Triticum aestivum L.)小偃22为供试植物,在全生育期人工控制土壤水分条件下,采用分层隔水土柱法研究了与田间土层分布相同土柱不同土层水分、氮、磷组合对冬小麦不同器官氮、磷养分累积及分配的影响.结果表明:(1)冬小麦不同器官氮、磷累积量表现为籽粒茎秆、叶>穗余部>根系.(2)与整体湿润处理相比,上干下湿水分处理可降低小麦各器官氮、磷累积量,但仅籽粒氮、磷累积量所占比例减少,而营养器官氮累积量所占比例均增加.(3)从肥料处理看,单施氮、单施磷和氮磷配施处理的小麦植株各器官氮、磷累积量均比对照增加,但籽粒氮、磷累积量所占比例均减小.(4)施肥层根系氮、磷累积量比对照相对增加,并以0～30cm土层根系氮、磷累积量为最高.(5)单施氮条件下,以0～90cm土层施肥各器官氮、磷累积量最高,0～30cm土层施肥最低;单施磷和氮磷配施时,以0～90cm土层施肥处理籽粒氮、磷累积量最高,其次是0～30cm土层施肥.由于石灰性土壤中肥料氮终产物以硝态氮为主且容易移动,而磷肥不易在土壤中迁移,在生产实践中仍以氮磷配施入0～30cm土层为佳.     

Isolate Virulence and Cultivar Response in the Winter Wheat: Pyrenophora tritici-repentis (Tan Spot) Pathosystem in Oklahoma

Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in split-plot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.     

Factors Controlling the Spatial Variability of Mercury Distribution in Spanish Topsoil

This study characterized the sources and scales of mercury variability in agricultural soils of the river Ebro (9.5 million ha) using geostatistical methods and data from 624 samples. The Ebro basin (20% of Spanish land mass) is an important agricultural area that is industrialized. Spatial analysis was done on a local scale (20 km) and indicated that high Hg concentrations were related to mining and specific agronomic practices, such as sewage effluents from irrigation. The intermediate scale (100 km) was associated with mercury from atmospheric deposition (mining, smelting, and industrial activities). The regional scale (220 km) corresponded to mineralogical structure and bedrock influence. The analysis demostrates that while geographical and geochemical processes and anthropogenic influences, such as industrialization and agricultural practices, can influence the content and distribution of mercury in the valley, the calcareous nature of the soils (alkaline pH and low organic matter) minimize the effect of the mercury load.     

Effects of Interaction Between Cadmium and Plumbum on Phytochelatins and Glutathione Production in Wheat (Triticum aestivum L.)

Phytochelatins (PCs) may function as a potential biomarker for metal toxicity. However, less attention has been paid to the effects of metal interactions on the production of PCs and glutathione (GSH),the most prominent cellular thiol. In the present study, the effects of interactions between cadmium (Cd) and plumbum (Pb) on the production of PCs and GSH were monitored over a period of 14 d in wheat (Triticum aestivum L.) tissues. The results showed that combination of Cd and Pb led to synergistic growth inhibition in wheat. Exposure to Cd or Pb increased levels of PCs in a concentration-, tissue-, and time-dependent manner. Cadmium was more effective that Pb in increasing PCs production. Compared with the effects of Cd or Pb alone on the production of PCs, the combination of Cd and Pb acted synergistically, resulting in an enhanced production of PCs. Cadmium also stimulated GSH production in a concentration-, tissue-, and time-dependent manner. However, Pb had no obvious effects on GSH levels. The combination of Pb and Cd antagonized GSH production over the course of the growth period. The results of the present study suggest that metal interactions should be considered in the application of PCs and GSH as potential biomarkers for the evaluation of metal toxicity.     

刈割对冬小麦再生积温需求及其籽粒产量和品质的影响

对黄土高原塬区冬小麦‘陇育216’于分蘖期、拔节期及孕穗期进行刈割处理,以不刈割为对照,测定冬小麦再生生长发育的积温需求及籽粒产量及其品质,探究刈割利用时间对冬小麦再生生长积温需求及产量构成的影响。结果表明:(1)分蘖中期(6个分蘖)前刈割利用,小麦再生各阶段的有效积温需求较对照无显著差异,在收获小麦青干草0.9～1.5t/hm2的同时,能保证籽粒、秸秆产量及其品质较对照均无显著下降;分蘖期后期(9个分蘖)及其后刈割利用,拔节至开花及成熟期的有效积温需求显著减少,尽管较分蘖期可多收获60%的青干草,但籽粒、秸秆产量较对照均显著降低。(2)通径分析发现,刈割主要通过降低再生植株高度及减少单位面积穗数而导致冬小麦籽粒减产。研究表明,为维持冬小麦再生生长节律、籽粒产量及品质形成的稳定,冬小麦刈割利用的时期应不迟于分蘖中期(6个分蘖)。     

不同穗型冬小麦品种根系时空分布特征及其碳氮代谢的研究

在大田柱栽试验条件下,对2种穗型冬小麦品种根系的时空变化及其碳氮代谢进行了研究。结果表明,2种穗型冬小麦品种的单株根系干重、根重密度随生育时期逐渐增加,均在抽穗期达到最大值;不同土壤深度的根系活力随生育时期的变化不一致,2品种0～20 cm根系活力的变化趋势从越冬期逐渐下降,在抽穗期达到较低值后缓慢上升,并于灌浆期出现一个小的峰值;根系中可溶性糖含量、含氮量均从越冬期开始下降,在抽穗期达到最低值, 随后在开花期又出现一个峰值后缓慢下降。2种穗型冬小麦品种相比,重穗型小麦品种的根系各项指标略高于多穗型品种;在不同土层深度之间,各项指标总体趋势为随着土层深度加深逐渐下降,但是在不同生育时期,各土层之间出现有个别波动现象。     

小麦旗叶Rubisco周转与籽粒含氮量的关系

随着旗叶的衰老,Rubisco含量逐渐减少.延缓小麦旗叶的衰老进程(抽穗期施氮肥),可增加旗叶Rubisco的含量,提高籽粒的全氮含量.在小麦旗叶全展后28d内,Rubisco的15N丰度处于较高水平,表明仍有Rubisco的重新合成;而在28d以后,Rubisco的15N丰度处于低水平,表明无Rubisco的重新合成.但这时籽粒的15N丰度却上升.旗叶全展后14d内Rubisco的15N丰度高于旗叶中全氮的丰度,说明此时期Rubisco重新合成的速率高于其它蛋白质;旗叶衰老过程中Rubisco的15N丰度的净转移高于全氮,Rubi-sco净N转移也高于全氮,表明Rubisco向籽粒中转移的氮素多于其它蛋白质,对籽粒含氮量的影响最大.     

小麦开花后旗叶中蔗糖合成与籽粒中蔗糖降解

在小麦开花后,旗叶中蔗糖磷酸合成酶（SPS）活性在开花后14d内一直维持较高水平,蔗糖合成酶（SS）的活性在开花后14-28d较高,蔗糖的含量与SPS活性呈显著正相关,籽粒中蔗糖合成酶（SS）在开花后28d内一直维持较高的活性;与此相对应,籽粒蔗糖的含量在开花后28d内呈明显的下降趋势。而旗叶和籽粒中SS活性均与籽粒淀粉的积累速率呈极显著正相关。