Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experiments were performed to explore the impact of sulfur nanoparticles (SNPs) on growth, Cu accumulation, and physiological and biochemical responses of oilseed rape (Brassica napus L.) inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure. Cu exerted severe phytotoxicity and inhibited plant growth. SNPs application enhanced the shoot height, root length, and dry weight of shoot and root by 34.6%, 282%, 41.7% and 37.1%, respectively, over Cu treatment alone, while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde (MDA) levels in shoots and roots were decreased by 37.6%, 35%, 28.4% and 26.8%. Further, the increases in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities caused by Cu stress were mitigated in shoots (10.9%–37.1%) and roots (14.6%–35.3%) with SNPs addition. SNPs also positively counteracted the negative effects on shoot K, Ca, P, Mg, Mn, Zn and Fe contents and root K, Ca, Mg and Mn contents from Cu exposure alone, and significantly promoted the nutrients accumulation in plant. Additionally, in comparison with common bulk sulfur particles (BSPs) and sulfate, SNPs showed more positive effects on promoting growth in shoots (6.7% and 19.5%) and roots (10.9% and 15.1%), as well as lowering the shoot Cu content (40.1% and 43.3%) under Cu stress. Thus, SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.     

有机肥与植物种类对铁肥形态转化及其有效性的影响

通过盆栽试验的方法,研究了牛粪和植物种类对石灰性土壤中铁肥形态转化及其有效性的影响。结果表明,牛粪施用改变了土壤中铁(含外源铁)的有效性及其在各形态铁间的分配。从长期的观点来看,牛粪施用能提高土壤铁的有效性,有利于土壤铁有效供给的维持。与花生相比,油莱对土壤铁具有更高的利用和活化能力,种植油菜后,土壤交换态铁被耗竭,而有效铁、氧化锰结合态铁和无定形氧化铁结合态铁的含量明显提高。有机肥的合理施用和铁效率差异性植物间的轮作或间作是增加、维系土壤铁有效性的重要农艺措施。     

铅胁迫下La(NO3)3对油菜抗氧化酶的影响

用盆栽实验研究了 1g·kg- 1和 2g·kg- 1铅胁迫下 ,分别以 0 1 ,0 3和 0 5g·l- 1La(NO3 ) 3 溶液浸种 ,然后测定油菜幼苗中超氧化物歧化酶 (SOD)、过氧化氢酶(CAT)的活性和脂质过氧化产物丙二醛 (MDA)的含量 ,以及油菜幼苗生长的情况 .结果表明 ,稀土元素镧可以提高油菜幼苗地上和地下部分超氧化物歧化酶和过氧化氢酶的活性 ,并降低丙二醛的含量 ,但是对于油菜幼苗生长的影响并不显著 ,显示镧能够在一定时间内抑制超氧阴离子自由基的产生以抵御铅的胁迫 .     

Hazard mitigation or mitigation hazard?

BACKGROUND, AIM AND SCOPE: Transgenic oilseed rape (Brassica napus L.; OSR) is estimated to be environmentally and economically problematic because volunteers and ferals occur frequently and because of its hybridisation potential with several wild and weedy species. A proposed mitigation strategy aims to reduce survival, in particular in conventional OSR crops, by coupling the transgenic target modification with a dwarfing gene to reduce competitive fitness. Our study allowed us to access potential ecological implications of this strategy. MATERIALS AND METHODS: On a large scale (>500 km(2)), we recorded phenological and population parameters of oilseed rape plants for several years in rural and urban areas of Northern Germany (Bremen and surroundings). The characterising parameter were analysed for differences between wild and cultivated plants. RESULTS: In rural areas, occurrences of feral and volunteer OSR together had an average density of 1.19 populations per square kilometre, in contrast to urban areas where we found 1.68 feral populations per square kilometre on average. Throughout the survey, the vegetation cover at the locations with feral OSR ranged from less than 10% to 100%. Our investigations gave clear empirical evidence that feral OSR was, on average, at least 41% smaller than cultivated OSR, independent of phenological state after onset of flowering. DISCUSSION: The findings can be interpreted as phenotypic adaptation of feral OSR plants. Therefore, it must be asked whether dwarfing could be interpreted as an improvement of pre-adaptation to feral environments. In most of the sites where feral plants occurred, germination and establishment were in locations with disturbed vegetation cover, allowing initial growth without competition. Unless feral establishment of genetically modified dwarfed traits are specifically studied, it would not be safe to assume that the mitigation strategy of dwarfing also reduces dispersal in feral environments. CONCLUSIONS AND RECOMMENDATIONS: With respect to OSR, we argue that the proposed mitigation approach could increase escape and persistence of transgene varieties rather than reducing them. We conclude that the development of effective hazard mitigation measures in the risk evaluation of genetically modified organisms requires thorough theoretical and empirical ecological analyses rather than assumptions about abstract fitness categories that apply only in parts of the environment where the plant can occur.     

A simulation study of the medium-term effects of field patterns on cross-pollination rates in oilseed rape (Brassica napus L.)

Gene flow between cultivars within a landscape may lead to impurities that reduce harvest value. In OSR, as for most crops, impurity rates are expected to depend on the spatial distribution of crops over the landscape. However, in contrast to other well-studied crops such as maize, OSR crops generate seed banks in European agro-ecosystems. Gene flow is thus a spatio-temporal process which depends on cropping systems. We therefore aimed at identifying spatial variables that have an effect on regional or local harvest impurities, taking account of the time since the introduction of OSR crops in the regions and of cropping system. Gene flow was simulated over 36 field patterns cultivated with either 15% or 30% of OSR fields, among which 10% or 50% were GM, for three contrasted cropping systems, with the GeneSys software already used for EU co-existence studies. Through regression analyses, we determined spatial and agronomic factors that most affected harvest impurity rates of non-GM OSR after one or seven years of OSR cultivation. The cropping system was the main factor explaining regional harvest impurity rates. Its importance increased after six years of OSR cultivation. For a given cropping system, the regional impurity rate after one year increased linearly with the current proportion of GM crop. In contrast, impurity rates after six years largely depended on the proportions of OSR crop (GM or not) in the two preceding years. During the first year of OSR cultivation, local impurity rates were mostly explained by the distance to the closest GM field. After six years, these rates were mostly explained by the density of GM volunteers in the analysed field and, to a lesser degree, to that of volunteers in neighbour non-OSR fields. Cropping systems were most important in determining impurity rates and the way impurity rates related to regional or local factors. Determination of isolation distances to ensure harvest purity should thus consider past history of OSR cultivation in the area and, in particular, how current or future cropping systems will manage volunteers. Regression quantiles were fitted to the simulated data to determine regional rules (i.e. the maximum regional area of GM OSR and isolation distances between GM and non-GM crops) as a function of the risk accepted by the decision-maker (i.e. the % of situations exceeding harvest impurity thresholds), the cropping system and the volunteer infestation.     

土壤中残留毒死蜱的作物效应

应用盆栽实验和室内分析方法,研究了红壤中残留毒死蜱农药对小麦、油菜苗生长及其对农药吸收的影响.结果表明,红壤中残留毒死蜱初始浓度为1～10μg/g,20d后,小麦苗地上部吸收的浓度可达0.257～4.50μg/g,油菜苗地上部吸收浓度可达到0.249～2.02μg/g;红壤中残留毒死蜱浓度低于10μg/g,对小麦苗地上部鲜重没有显著影响,低于5μg/g,对油菜苗地上部鲜重没有显著影响;残留毒死蜱在油菜苗根际的降解比非根际快1.4～4.2倍;油菜苗根际土细菌、真菌数量分别是非根际土的3.18倍、1.84倍,而放线菌数量差异不大;根际土比非根际土pH值低约0.19～0.23.     

不同种植制度对稻田旱作季节CH4和N2O排放的影响

通过大田试验研究了稻田旱作季节几种典型种植制度对CH4和N2O排放的影响,包括休闲（fallow）、油菜对照（OR-ck）、小麦对照（W-ck）、油菜施N（OR-N）和小麦施N（W-N）5个处理。试验结果表明,稻田旱作季节N2O排放明显,CH4排放量较低,甚至表现为弱的CH4汇。稻田旱作季节N2O排放除受到N肥和种植制度影响外,还受土壤含水量影响,施N处理显著促进了N2O排放,降雨后N2O排放明显。小麦和油菜施N处理N2O平均排放通量分别为18.51和13.47μg·m^-2·h^-1,季节累积排放量分别为87.31和59.48 mg·m^-2,均显著高于对照和休闲处理。不同作物种类间N2O平均排放通量无显著差异,N2O季节累积排放量则表现为小麦显著高于油菜。各处理综合温室效应（100 a）依次为：OR-N〉W-N〉W-ck〉fallow〉OR-ck。各施N处理综合温室效应以N2O为主,但各无N处理则以CH4为主,也不容忽视。     

Secondary metabolites of the leaf surface affected by sulphur fertilisation and perceived by the diamondback moth

Summary. Summary. Oilseed rape, Brassica napus L. (cv Express), plants were grown under three different sulphur regimes: sulphur-free (S₀), normal sulphur (S_n, normal field concentration) and a sulphur-rich (S₊, 2 × concentration of S_n). We performed dual choice oviposition assays with the diamondback moth, Plutella xylostella, using real plants and, for the first time with this insect, artificial leaves sprayed with methanolic leaf-surface extracts. The results mirrored those of a separate study of preferences for whole plants. Females laid more eggs on surrogate leaves that were treated with S_n extracts than on S₀ plants, while only a slight, not significant, difference was observed between extracts of normal and sulphur-rich plants. This shows that chemical compounds on the leaf surface mediate the oviposition preference and that the female insect can perceive the quality of the host-plants in terms of their fertilisation status.Since leaf volatiles are known to be oviposition stimulants, we investigated the effects of leaf-surface extracts on insect olfactory responses using electroantennograms (EAGs). In agreement with the behavioural data, we found that extracts of sulphur-treated plants yielded higher EAG amplitudes than the S₀ extracts. Since the leaf content of the volatiles isothiocyanates is influenced by sulphur nutrition, we analysed the extracts for these compounds. Above the detection threshold of our GC-MS system, no isothiocyanates were found. Thus, other compounds present in the surface extracts must be perceived by the antenna.However, the HPLC analysis revealed 11 different glucosinolates. Progoitrin (2-Hydroxy-3-butenyl) and gluconapoleiferin (2-Hydroxy-4-pentenyl), which belong to the hydroxy-alkene class of glucosinolates, were the most abundant compounds. The total glucosinolate content sharply increased from S₀ to S_n plants, whereas it was slightly lower in _n versus S₊ plants. Since it is known that glucosinolates can stimulate oviposition, it seems likely that the increased content we observed was influencing the insect preference in this study too.     

Cadmium uptake and speciation changes in the rhizosphere of cadmium accumulator and non-accumulator oilseed rape varieties

Characteristics of cadmium (Cd) uptake kinetics and distribution of Cd speciation in the rhizosphere for Cd accumulator and non-accumulator oilseed rape varieties were investigated under nutrient solution and rhizobox soil culture conditions. The results showed that the maximal influx (V_max) for Cd²⁺ andK_m were significantly different for the two oilseed rape varieties. The value of V_max for Cd accumulator oilseed rape Zhucang Huazi was two-fold greater than that for oilseed rape Chuan you II-93. The exchangeable Cd concentration in the rhizosphere was significantly lower than in non-rhizospheric soils supplemented with CdSO₄ for both the varieties. Carbonate-bound Cd in the rhizosphere of Cd accumulator oilseed rape was significantly higher than that in the rhizosphere of non-accumulator oilseed rape and non-rhizospheric soil. Cd accumulator oilseed rape had a higher Cd²⁺ affinity and more ability to uptake insoluble Cd in the soil than the non-accumulator oilseed rape.     

3类抗性种子萌发过程中糖代谢对酸雨胁迫的响应

为揭示酸雨影响种子萌发机理,以pH 2.0、2.5、3.0、3.5、4.0、4.5、5.0的模拟酸雨处理水稻(O.sativa)、小麦(T.aestivum)、油菜(B.chinensis var.oleifera)3种不同抗性种子,研究种子萌发糖代谢对酸雨胁迫的响应.结果表明,水稻、小麦和油菜α-淀粉酶活性、可溶性糖和还原糖含量随胁迫强度增加(pH 5.0～2.0)而降低,均低于对照.3个指标响应酸雨胁迫强度的规律(伤害阈值/变幅)是:水稻(pH 3.5～4.0/53.88%～77.7%)＜小麦(pH 3.5～4.5/58.60%～89.41%)＜油菜(pH 4.0～5.0/60.14%～100%).胁迫强度一定时,水稻α-淀粉酶活性、可溶性糖和还原糖含量随时间延长而上升,小麦和油菜3个指标先升后降.胁迫时间一定时(3～7 d),3种种子处理组的旺α-淀粉酶活性、可溶性糖和还原糖含量均低于对照,且随胁迫强度增加而降低.3个指标达到最大伤害的胁迫时间为水稻(7 d;7 d,7 d)＞小麦(7 d,6 d,5 d)＞油菜(3 d,7 d,5 d).3个指标对酸雨胁迫强度与胁迫时间的响应规律显示,水稻糖代谢抗酸雨能力＞小麦＞油菜,这是酸雨胁迫下3类种子萌发指标趋异的又一内在原因.