莫莫格扁秆藨草恢复湿地土壤种子库对长芒稗入侵的响应

湿地恢复过程中,时常有外来种或本地杂草入侵。土壤种子库作为未来植被的潜在种源,对湿地恢复效果具有重要的指示意义。在莫莫格国家级自然保护区,以恢复白鹤栖息地(扁秆藨草(Scirpus planiculmis)沼泽)为目的,进行了退化湿地的水文恢复;但退化湿地恢复2a后,一年生杂草长芒稗(Echinochloa caudata)在大部分区域成为建群种。以长芒稗入侵湿地和扁秆藨草自然湿地为研究对象,对比分析了长芒稗和扁秆藨草的土壤种子库及生长结实特征。结果表明,在自然湿地扁秆藨草种子库规模是长芒稗的18.42倍,而在恢复湿地长芒稗种子库大小是扁秆藨草的5.04倍。与自然湿地相比,扁秆藨草种子库密度在入侵湿地明显减少,但仍保留了一定量具有活力的种子(664.32±105.98)粒/m~2,这与研究区扁秆藨草较高的种子生产力(9210.4±1513.4)粒/m~2及种子较强的浮力(FP50=39.7d)有关,说明扁秆藨草具备通过种子库或水传播恢复的潜力。长芒稗土壤种子库密度在入侵湿地高达(3345.9±520.3)粒/m~2,明显高于自然湿地种子库规模(P0.01),说明恢复湿地受长芒稗入侵影响严重,这与长芒稗较高的种子生产力(7621.4±376.25)粒/m~2及较弱的种子浮力(FP0=5d)有关,同时也表明长芒稗通过水传播扩散的能力较弱。另外,研究区长芒稗平均高度超过1m,且盖度较大,不仅阻碍扁秆藨草种子的水播,也降低了到达地表的光照水平,从而抑制扁秆藨草更新。因此,在莫莫格受长芒稗入侵湿地,于开花结实前收获长芒稗地上植物体及凋落物应是限制长芒稗扩展、同时促进扁秆藨草恢复的有效措施。     

A NEW SPECIES OF ECHINOCHLOA FROM CHINA

Haec species nova spiculis ommino persistentibus numquam deciduis a congeneribus diversa.     

Antioxidative responses and their relation to salt tolerance in <Emphasis Type="Italic">Echinochloa oryzicola</Emphasis> Vasing and <Emphasis Type="Italic">Setaria virdis</Emphasis> (L.) Beauv.

Two gramineous species among wild plants, Echinochloa oryzicola Vasing and Setaria viridis (L.) Beauv., and Oryza sativa L. cv. Nipponbare were subjected to salt stress. The relative growth rate (RGR), Na content, photosynthetic rate, antioxidant enzymes activity (superoxide disumutase (SOD), catalase (CAT), ascorbate peroxidase (APx) and glutathione reductase (GR)), and malondialdehyde (MDA) content in leaves after NaCl treatment were studied. RGR significantly decreased in O. sativa more than in E. oryzicola and S. viridis. Comparatively salt-tolerant S. viridis showed higher growth rate, lower Na accumulation rate in leaves, higher photosynthetic rate, and induced more SOD, CAT, APx, and GR activity and lower increase of MDA content as compared to the salt-sensitive O. sativa. At the same time, the comparatively salt-tolerant E. oryzicola also showed higher growth rate, much lower Na accumulation and no observable increase of MDA content, even though the CAT and APx activities were not induced by salinity. These results suggested that the scavenging system induced by H₂O₂-mediated oxidative damage might, at least in part, play an important role in the mechanism of salt tolerance against cell toxicity of NaCl in some gramineous plants     

中国主要农区稻田稗草分类与多样性研究

将采自中国15个省和1个直辖市的206份稗属（Echinochloa）植物种子分别播种在相同栽培条件下,获得了206份子代样本及其21项形态性状数据,基于这些形态性状对206份稗属植物样本进行了聚类和主成分分析。结果表明：（1）从206份稗属植物样本中鉴别出了形态性状相对一致的8个分类群（G1-G8）,依次对应于湖南稗子（Echinochloa frumentaceae,2份样本）、水田稗（E.oryzoides,5份）、细叶旱稗（E.crus-galli var.praticola,6份）、硬稃稗（E.glabrescens,14份）、光头稗（E.colona,2份）、长芒稗（E.caudata,16份）、孔雀稗（E.cruspavonis,8份）、稗复合群（稗原变种E.crus-galli var.crus-galli、稗的变种无芒稗var.mitis、短芒稗var.breviseta和西来稗var.zelayensis,共150份）,还有3份样本没有聚合成组。它们依次占总样本量的0.97%、0.97%、2.42%、2.91%、3.88%、7.77%、6.80%、72.81%和1.46%,反映出中国主要农区稻田稗属植物主要以稗及其变种为主;（2）单因素方差分析表明,9个数量性状,包括叶长、叶宽、圆锥花序长度、总状花序长度、小穗芒长、小穗长度、第1颖长度/小穗长度、主茎直径和株高,在稗属植物的8个分类群（G1-G8）之间有显著差异;（3）根据8个分类群之间的形态性状特点及差异,给出了鉴别中国主要农区稻田稗属植物的分种检索表;（4）由于细叶旱稗具有总状花序简单、小穗无芒、叶较宽、植株高大、小穗紫黑色等独特形态性状,在206份稗属植物样本的聚类图上单独聚成一组,故建议将细叶旱稗作为独立种处理。     

The Effect of EDTA Addition on the Phytoremediation Efficiency of Pb and Cr by Echinochloa crus galii (L.) Beave and Associated Potential Leaching Risk

Metal-contaminated soils constitute a serious environmental problem with adverse consequences for human health. This study was conducted to determine phytoextraction efficiency of Echinochloa crus galii for Pb and Cr and the EDTA-assisted (0. 2.5, 5, 10 mmol kg^?1) phytoextraction and the potential for leaching of the metals during the phytoextraction process. The results revealed that the bioconcentration factors of roots of the plant were relatively higher than the bioconcentration factors of the shoot. Thus, the plant species of E. crus galii would be applicable for Pb and Cr phytostabilization. Addition of EDTA had virtually a significant effect on uptake of the metals by the plant and elevated Pb and Cr concentrations in plant organs as compared with the control. Optimum phytoextraction was observed when 5 mmol kg^?1 EDTA was added in a single dosage 60 days after the plant cultivation and consequently soil Pb and Cr concentration decreased with the passage of time.     

二氯喹啉酸对稗草生长发育及生长素含量的影响

通过外施二氯喹啉酸、生长素处理,研究二氯喹啉酸对稗草Echinochloa crusgalli生长特性、蛋白浓度、过氧化物酶及超氧化物歧化酶活性、生长素含量的影响。结果表明,800 g·hm-2二氯喹啉酸处理24 h未对S型稗草的生长产生明显抑制,而二氯喹啉酸单独处理及外施IAA的二氯喹啉酸处理均能显著增加R型稗草鲜重。在不施药、二氯喹啉酸单独处理、二氯喹啉酸与IAA共同处理的条件下,R型稗草比S型稗草的蛋白浓度分别提高23.5%、29.8%和64.0%,R型稗草表现出较高的抗逆境耐受能力。经二氯喹啉酸处理后,两种生物型稗草SOD活性上升,POD活性下降。施外源IAA能提高S型稗草POD活性,而对R型稗草SOD、POD活性影响不显著。提高生长素含量可显著促进R型稗草的生长。     

Vegetative salt tolerance of barnyard grass mutants selected for salt tolerant germination

Improving salt tolerance of economically important plants is imperative to cope with the increasing soil salinity in many parts of the world. Mutation breeding has been widely used to improve plant performance under salinity stress. In this study, we have mutagenized Echinochloa crusgalli L. with sodium azide and three selected mutants (designated fows A) with salt tolerant germination. Their vegetative growth was compared to that of the wild type after short-term and long-term salt stress. The germination of the three fows A mutants in the presence of inhibitory concentrations of NaCl, KCL, and mannitol was better than that of the wild type. Early growth of the mutants in the presence of 200 mM NaCl was also better than that of the wild type perhaps due to improved K⁺ uptake and enhanced accumulation of sugars particularly sucrose at least in two mutants. But the three mutants and the wild type responded similarly to long-term salt stress. The tolerance mechanisms during short-term and long-term salt stress are discussed.     

下辽河平原不同磷肥用量对作物产量及潜在养分的影响

通过6年的定位试验,对下辽河平原不同磷肥用量条件下,土壤养分库的建立及磷肥的肥料效应、土壤磷的自然释放速率等进行了研究。结果表明：磷肥可以提高作物的产量,且对大豆的增产幅度大于玉米,但磷肥年用量超过25 kg·hm^-2时,增产效果不明显;磷肥也可以提高作物的养分移出量,但养分移出量增加的比例大于作物产量增加的比例;磷肥利用率随着磷肥用量的增加而减小,当磷肥年用量为25 kg·hm^-2时,磷肥利用率约为30％,但残留磷肥转化为有效磷的比例随着磷肥用量的增加而增大;磷肥施入土壤后,残留磷肥转化为迟效磷的比例高达80%,且残留磷肥转化为迟效磷的量随着磷肥用量的增加而增加,这对于构建土壤磷库有重要意义。     

Differences in photosynthetic characteristics among northern and southern C4 plants

Both responses to short-term changes of temperature and to chilling under high light were analyzed in populations of Echinochloa crus-galli var. crus-galli (L.) Beauv. from Québec. North Carolina and Mississippi to improve the understanding of C₄ photosynthesis at low temperature. Comparison also included plants of Eleusine indica (L.) Gaertn. from Mississippi to provide for differences among species and populations. Plants were grown at two thermoperiods (28/22°C, 21/15°C). After transfer from cool (21/15°C) to warm (28/22°C) growth conditions, Echinochloa from Mississippi achieved the highest photosynthetic rates. Plants from Québec maintained the highest rates of CO₂ uptake upon transfer to cool conditions. Exposure to 7°C for 3 days at a photon fluence rate of 1000 μmol m−²s−¹ resulted in a reduction in the growth rates of all populations. This reduction was paralleled by a decrease in net photosynthesis and in stomatal conductance. Following chilling under hight light, the reduction in growth parameters was less important for plants from Québec than for the other populations. It suggests that, among other characteristics, northern plants had developed a certain tolerance to chilling under light.     

Distribution of alcohol dehydrogenase in roots and shoots of rice (Oryza sativa) and Echinochloa seedlings

Abstract Aerobically germinated seedlings of rice and Echinochloa were found to survive when placed in an anaerobic environment for 4 d, whereas pea and maize seedlings did not. Although root and shoot growth were inhibited in rice and Echinochloa under anaerobiosis, growth resumed when the seedlings were returned to aerobic conditions. Alcohol dehydrogenase (ADH) activity increased more, and protein synthesis was greater, in the shoots than in the roots under anaerobic conditions. These results suggest that, in anaerobiosis-tolerant species, ADH activity and protein synthesis in the shoots represents or results from metabolic adaptations to low oxygen. These results are discussed in terms of plant establishment and growth in a low-oxygen environment.