小叶章种群高度的季节动态

探讨了三江平原以小叶章为优势种的典型草旬、沼泽化草甸、沼泽３个植被类型中小叶章种群高度的变化规律。结果表明,在３个类型中,种群高度的季节动态均呈单峰型,极大值均出现在７月末,分别为１１２．６７ｃｍ、１０１．６１ｃｍ、８３．８８ｃｍ。ＨＡＧＲ的季节动态在７月末之前〉０,之后〈０;典型草甸和沼泽化草甸的极大值出现在６月末至７月中旬,沼泽则出现在６月中旬至６月末;极小值典型草甸出现在８月末至９月中旬,而     

Comparison of EDTA- and Citric Acid-Enhanced Phytoextraction of Heavy Metals in Artificially Metal Contaminated Soil by Typha Angustifolia

A pot experiment was conducted to study the performance of EDTA and citric acid (CA) addition in improving phytoextraction of Cd, Cu, Pb, and Cr from artificially contaminated soil by T. angustifolia. T. angustifolia showed the remarkable resistance to heavy metal toxicity with no visual toxic symptom including chlorosis and necrosis when exposed to metal stress. EDTA-addition significantly reduced plant height and biomass, compared with the control, and stunted plant growth, while 2.5 and 5 mM CA addition induced significant increases in root dry weight. EDTA, and 5 and 10 mM CA significantly increased shoot Cd, Pb, and Cr concentrations compared with the control, with EDTA being more effective. At final harvest, the highest shoot Cd, Cr, and Pb concentrations were recorded in the treatment of 5 mM EDTA addition, while maximal root Pb concentration was found at the 2.5 mM CA treatment. However, shoot Cd accumulation in the 10 mM CA treatment was 36.9% higher than that in 2.5 mM EDTA, and similar with that in 10 mM EDTA. Shoot Pb accumulation was lower in 10 mM CA than that in EDTA treatments. Further, root Cd, Cu, and Pb accumulation of CA treatments and shoot Cr accumulation in 5 or 10 mM CA treatments were markedly higher than that of control and EDTA treatments. The results also showed that EDTA dramatically increased the dissolution of Cu, Cr, Pb, and Cd in soil, while CA addition had less effect on water-soluble Cu, Cr, and Cd, and no effect on Pb levels. It is suggested that CA can be a good chelator candidate for T. angustifolia used for environmentally safe phytoextraction of Cd and Cr in soils.     

沙枣花蜜腺的发育解剖学研究

沙枣的花蜜腺位于花柱基部的筒状花盘上,属花盘蜜腺,其蜜腺位于花盘外方,由分履表皮和产蜜组织组成。分泌表皮具有角质层和变态的气孔器。产蜜组织在发育过程中,其液泡和淀粉粒都随着蜜腺的发育呈现一定的消长规律,最后形成的蜜汁由盘状蜜腺表面的气孔泌出。     

Distribution and N2-fixing activity of Frankia strains in relation to soil depth

The qualitative and quantitative distribution of Frankia strains infective on Elaeagnus angustifolia L. from different depths in the same soil (10–20 cm; 30–40 cm; 50–60 cm) were compared. The soil samples collected from a natural stand devoid of Elaeagnaceae were planted with Elaeagnus angustifolia L. seedlings. All plants became nodulated, demonstrating that Frankia strains were present at least down to 60 cm in the soil. The decreased density of Frankia strains was correlated to the decline of soil organic matter content with soil depth. DNA extracted from nodules produced on Elaeagnus angustifolia L. seedlings were polymerase chain reaction (PCR) characterized by amplifying the nif D-K intergenic spacer (IGS), using the polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis. This showed the presence of seven nif-Hae III profiles within this Frankia community. Diversity of Frankia strains was maintained throughout the soil column, but the relative distribution of strains varied. Some nif-Hae III profiles were only found in the deeper soil, suggesting different selective advantages to withstand the constraints of soil depth. ¹⁵N₂ experiments indicated that all the strains tested had N₂-fixing activity. However, efficiency was not significantly different among nodules of different nif-Hae III profiles. Therefore, N₂-fixing activity does not seem to be the main factor responsible for the different distribution of Frankia strains at different soil depths.     

The effects of non-host plant essential oil volatiles on the behaviour of the pollen beetle Meligethes aeneus

The use of semiochemicals for manipulation of the pollen beetle Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae) is being investigated for potential incorporation into a push‐pull control strategy for this pest, which damages oilseed rape, Brassica napus L. (Brassicaceae), throughout Europe. The response of M. aeneus to non‐host plant volatiles was investigated in laboratory assays to establish whether they have any effect on host plant location behaviour. Two approaches were used. First a novel, moving‐air bioassay using air funnels was developed to compare the response of M. aeneus to several non‐host plant essential oils. The beetles avoided the host plant flowers in the presence of non‐host volatiles, suggesting that M. aeneus uses olfactory cues in host location and/or acceptance. The results were expressed as ‘repellency values’ in order to compare the effects of the different oils tested. Lavender (Lavendula angustifolia Miller) (Lamiaceae) essential oil gave the highest repellency value. In addition, a four‐arm olfactometer was used to investigate olfactory responses, as this technique eliminated the influence of host plant visual and contact cues. The attraction to host plant volatiles was reduced by the addition of non‐host plant volatiles, but in addition to masking the host plant volatiles, the non‐host volatiles were avoided when these were presented alone. This is encouraging for the potential use of non‐host plants within a push‐pull strategy to reduce the pest colonisation of crops. Further testing in more realistic semi‐field and field trials is underway.     

Biogeochemical cycle of Sulfer in the Calamagrostis angustifolia wetland ecosystem in the Sanjiang Plain, China

To better understand the Sulfur (S) cycle in the wetland ecosystem, the S cycle and its compartmental distribution within an atmosphere-plant-soil system were studied using a compartment model in the Calamagrostis angustifolia wetland in the Sanjiang Plain, Northeast China. The results showed that the soil was the main S storage and flux hinge in which 97.78% S was accumulated. In the plant subsystem, the root was the main S storage, and it remained at 79.60% of the total S contents, which in the Calamagrostis angustifolia wetland ecosystem showed that the parts above the ground took up 0.75 g S/m², the S re-transferring biomass to the root was 0.24 g S/m², and to the litter was 0.51 g S/m²; the root took up 3.76 g S/m² and the S transferring biomass to the soil took up 3.07 g S/m²; the litter S biomass was 0.75 g S/(m²·a) and the S transferring biomass to the soil was more than 0.52 g S/(m²·a). The emission amount of H2S from the Calamagrostis angustifolia wetland ecosystem to the atmosphere was 1.42 mg S/m², whereas carbonyl sulfide (COS) was absorbed by the Calamagrostis angustifolia wetland from the atmosphere and the absorption amount was 1.83 mg S/m². The S input biomass from the rain to the ecosystem was 4.85mg S/m² during the growing season. The difference between input and output amounts was 5.26 mg S/m², which indicated that S was accumulated in the ecosystem and would lead to wetland acidification in the future.     

An examination of hybridization between the cattail species typha latifolia and typha angustifolia using random amplified polymorphic DNA and chloroplast DNA markers

Typha glauca represents a significant portion of the biomass of the wetlands surrounding the Great Lakes, USA. It is generally accepted to be a form of hybrid between T. latifolia and T. angustifolia, which itself appears to be an exotic introduction from Europe. Based on morphological and isozyme data, conflicting theories have been proposed for the hybrid nature of T. glauca: it has been described as a hybrid swarm, a distinct hybrid species and an F1 hybrid. Therefore, we developed random amplified polymorphic DNA (RAPD) and chloroplast DNA markers, specific to the parental species, to assess hybrids. Ten RAPD primers gave 17 fragments specific to T. angustifolia and 13 fragments specific to T. latifolia. All of the interspecific hybrids contained each of the species-specific markers, indicating an F1 hybrid status. Furthermore, all hybrids tested contained the T. angustifolia chloroplast haplotype, which is consistent with differential interspecific crossing success found previously. Additional confirmation of an F1 hybrid status was gained by examining seedlings from T. glauca. These progeny were expected to be advanced-generation hybrids, as opposed to the F1 hybrid parent. Analysis of the seedlings revealed segregating marker patterns consistent with patterns observed in experimental advanced-generation hybrids, although these advanced hybrids do not appear to be a significant part of mature stands. Our data do not provide support for extensive gene flow between T. latifolia and T. angustifolia. However, our results suggest that hybridization between the native and introduced Typha species has impacted the native population through the spread of the F1 hybrid, T. glauca.     

三江平原典型草甸小叶章种群地上器官生物量及其分层结构

混合盐胁迫对星星草幼苗光合特性的影响,在短期盐胁迫(6d)和长期盐胁迫(45d)下是不同的。在短期盐胁迫下,小于1.0%的盐胁迫对星星草幼苗光合速率影响不大,甚至还会有一定的促进作用,而超过1.0%以后则迅速降低。气孔导度在盐胁迫下的变化与光合速率的变化基本一致,均随着盐胁迫的增加而降低,而对内的CO₂浓度在整个盐胁迫范围内均增加。     

Responses of apical ion fluxes to NaCl stress in Elaeagnus angustifolia seedlings

Aims Elaeagnus angustifolia is one of the most salt-tolerant species. The objective of this study was to understand the mechanisms of ion transporation in E. angustifolia exposed to different salt concentrations through manipulations of K⁺/Na⁺ homeostasis.
Methods Seedlings of two variants of the species, Yinchuan provenance (YC, salt-sensitive type) and the Alaer provenance (ALE, salt-tolerant type), were treated with three different NaCl application modes, and the ion fluxes in the apical regions were measured using non-invasive micro-test technology (NMT). In mode 1, Na⁺ and K⁺ fluxes were measured after 150 mmol·L^-1 NaCl stress lasted for 24 h. In mode 2, K⁺ and H⁺ fluxes were quantified with a transient stimulation of NaCl solution. In mode 3, Amiloride (Na⁺/H⁺ antiporters inhibitor) and tetraethylammonium (TEA, K⁺ channel inhibitor) was used to treat apical regions of E. angustifolia seedlings after NaCl stress for 24 h, respectively.
Important findings Under NaCl stress for 24 h, net effluxes of Na⁺ and K⁺ were increased significantly. The net Na⁺ effluxes of YC provenance seedlings (720 pmol·cm^-2•s^-1) were lower than that of ALE provenance (912 pmol·cm^-2·s^-1), but the net K⁺ efflux was higher in YC provenance. Under the instantaneous NaCl stimulation, net K⁺ efflux was remarkably increased, with the net K⁺ efflux of YC provenance always higher than that of ALE provenance. Interestingly, H⁺ at the apical regions was found from influx to efflux, with the net H⁺ efflux of ALE provenance greater than that of the YC provenance. Under the NaCl and NaCl + Amiloride treatment, the net Na⁺ efflux of ALE provenance seedlings was higher than that of YC provenance, while the net K⁺ efflux was less in ALE provenance seedlings. On the other hand, the differences in net Na⁺ and K⁺ effluxes were insignificant between the two provenances under the control group and NaCl + TEA treatment. In conclusion, NaCl stress caused Na⁺ accumulation and K⁺ outflows of E. angustifolia seedlings; The E. angustifolia seedlings utilize Na⁺/H⁺ antiporters to reduce Na⁺ accumulation by excretion; and the maintenance of K⁺/Na⁺ homeostasis in salt-tolerant E. angustifolia provenance seedlings roots accounted for a greater Na⁺ extrusion and a lower K⁺ efflux under NaCl stress. Results from this study provide a theoretical basis for further exploring salt-tolerant E. angustifolia germplasm resource.     

Typha×glauca Godr.,香蒲属(香蒲科)中国新记录杂种及其形态特征

香蒲属(Typha L.)为多年生水生或沼生草本植物, 种间存在十分普遍的杂交现象, 其中一些杂种在湿地生态系统中有重要的作用。在查阅大量腊叶标本基础上, 结合野外居群生物学工作, 作者发现中国一新记录杂种, 即T.×glauca Godr. (T. angustifolia L.×T. latifolia L.), 并新拟“粉绿香蒲”作该杂种的中文名。对粉绿香蒲的形态特征进行了研究, 讨论了其与亲本水烛和宽叶香蒲的区别, 并给出检索表。