Effect of Flower Removal on Senescence and Metabolism of Faba Bean(Vicia Faba L.)

In pot experiments at Xichang,China,during 1989～1994,visual senescencesymptoms and associated changes in constituent contents and activities of leaves of fababean(Vicia faba L.)were compared in respones to flower removal.The leaves from upper,middle and lower positions were sampled six times during reproductive developmentphase.At 70 DAP flower removal had caused 37%～189% and 82%～197% increase ofgreen leaf area and green leaf dry weight per plant respectively.Flower removal led to asignificant increase in the chlorophyll,soluble sugar and protein contents and the catalaseactivity.The leaf cell relative electroconductivity of those plants was maintained at a lowerlevel,relative to the control,during the late growing stage.These results certainly impliedthat the leaves of flower removal plants were still fully functional at a very late growingstage,consequently the plants increased many new branches per plant.     

Growth,physiological characteristics and ion distribution of NaCl stressed Alhagi sparsifolia seedlings

Alhagi sparsifolia is a leguminous perennial desert species that is plays an important role in dune stabilization and revegetation of degraded desert ecosystems. We investigated the effects of three different levels of salinity (50, 150, 250 mmol/L NaCl) on the growth, shoot photosynthetic parameters and salt distribution amongst different plant organs in one-year-old A. sparsifolia seedlings in a pot experiment over a 50 d period. The minimum (predawn) and maximum (midday) water potentials of A. sparsifolia seedlings decreased with the increase of external NaCl concentrations as a consequence of the osmotic or water deficit effect of saline solutions outside the roots. Salinity also reduced gas exchange parameters in A. sparsifolia, with seedlings subjected to salinity having lower photosynthesis rates and reduced stomatal conductances compared to the control. The reductions in photosynthetic rates in high salinity treatments of the A. sparsifolia seedlings were mainly caused by stomatal limitation. Consequently plants growing at greater external NaCl concentrations had significantly lower biomass accumulation compared to the control grown at 50 mmol/L. However, plants exposed to higher salinity were able to maintain growth throughout the experiment but allocated a greater proportion of biomass belowground. Plants exposed to higher external salinity levels had increased concentrations of Na+ and Cl- ions in shoots and roots, suggesting that A. sparsifolia seedlings were utilizing Na+ and Cl- as osmolytes to increase the cellular osmolality and decrease their water potential. We observed the greatest NaCl concentrations in the plants treated with 150 mmol/L NaCl indicating that there may be a threshold level of NaCl that can be tolerated by the plants. In conclusion our results indicate that A. sparsifolia seedlings are moderately salt tolerant. Photosynthetic gas exchange parameters were reduced by greater external salinity but the seedlings maintained substantial photosynthetic rates even under high salinity s     

Earliest record of megaphylls and leafy structures, and their initial diversification

Evolutionary changes in the structure of leaves have had far-reaching effects on the anatomy and physiology of vascular plants, resulting in morphological diversity and species expansion. People have long been interested in the question of the nature of the morphology of early leaves and how they were attained. At least five lineages of euphyllophytes can be recognized among the Early Devonian fossil plants (Pragian age, ca. 410 Ma ago) of South China. Their different leaf precursors or "branch-leaf complexes" are believed to foreshadow true megaphylls with different venation patterns and configurations, indicating that multiple origins of megaphylls had occurred by the Early Devonian, much earlier than has previously been recognized. In addition to megaphylls in euphyllophytes, the laminate leaf-like appendages (sporophylls or bracts) occurred independently in several distantly related Early Devonian plant lineages, probably as a response to ecological factors such as high atmospheric CO 2 concentrations. This is a typical example of convergent evolution in early plants.     

The mechanism and products for co-thermal extraction of biomass and low-rank coal with NMP

The high-value utilization of low-rank coal would allow for expanding energy sources, improving energy efficiencies, and alleviating environmental issues. In order to use low-rank coal effectively, the hypercoals(HPCs) were co-extracted from two types of low-rank coal and biomass via N-methyl-2-purrolidinone(NMP) under mild conditions. The structures of the HPCs and residues were characterized by proximate and ultimate analysis, Raman spectra, and Fourier transform infrared(FT-IR) spectra. The carbon structure changes within the raw coals and HPCs were discussed. The individual thermal dissolution of Xibu(XB) coal, Guandi(GD) coal, and the biomass demonstrated that the biomass provided the lowest thermal dissolution yield Y_1 and the highest thermal soluble yield Y_2 at 280℃, and the ash content of three HPCs decreased as the extraction temperature rose. Co-thermal extractions in NMP at various coal/biomass mass ratios were performed, demonstrating a positive synergic effect for Y_2 in the whole coal/biomass mass ratios. The maximum value of Y_2 was 52.25 wt% for XB coal obtained with a XB coal/biomass of 50 wt% biomass. The maximum value of Y_2 was 50.77 wt% for GD coal obtained with a GD coal/biomass of 1:4. The difference for the optimal coal/biomass mass ratios between XB and GD coals could be attributed to the different co-extraction mechanisms for this two type coals.     

Functional characterization and mapping of two MADS box genes from peach （Prunus persica）

Previously an AGAMOUS gene homologue PpMADS4 and a FRUITFULL gene homologue PpMADS6 were isolated from peach （Prunus persica）, and both genes were shown to express in the developing floral and fruits. To gain insight into their function, the two genes were constitutively expressed in Arabidopsis thaliana and their effects on plant growth and floral organ development were studied in this work. The transgenic plants all displayed early flowering and conversion of inflorescence to floral meristem. However, the two genes had different effects on the floral organ structures in A. thaliana. The transgenic plants overexpressing PpMADS4 displayed homeotic conversion of floral organs, and particularly the perianth abscission was inhibited. The plants overexpressing PpMADS6 showed early flowering, produced higher number of carpels, petals, and stamens than nontransgenic plants, and pod shatter was prevented; significantly, the transgenic plants yielded more than one siliques from a single flower. A SSR molecular marker was developed for PpMADS4, and it was then assigned into the G5 linkage group of Prunus sp. Both PpMADS4 and PpMADS6 genes were located at the same region in the G5 linkage group. Our results showed the potential application of these two MADS box genes for crop and fruit tree improvement.     

Functional characterization and mapping of two MADS box genes from peach (Prunus persica)

Previously an AGAMOUS gene homologue PpMADS4 and a FRUITFULL gene homologue PpMADS6 were isolated from peach (Prunus persica), and both genes were shown to express in the developing floral and fruits. To gain insight into their function, the two genes were constitutively expressed in Arabidopsis thaliana and their effects on plant growth and floral organ development were studied in this work. The transgenic plants all displayed early flowering and conversion of inflorescence to floral meristem. However, the two genes had different effects on the floral organ structures in A. thaliana. The transgenic plants overexpressing PpMADS4 displayed homeotic conversion of floral organs, and par- ticularly the perianth abscission was inhibited. The plants overexpressing PpMADS6 showed early flowering, produced higher number of carpels, petals, and stamens than nontransgenic plants, and pod shatter was prevented; significantly, the transgenic plants yielded more than one siliques from a single flower. A SSR molecular marker was developed for PpMADS4, and it was then assigned into the G5 linkage group of Prunus sp. Both PpMADS4 and PpMADS6 genes were located at the same region in the G5 linkage group. Our results showed the potential application of these two MADS box genes for crop and fruit tree improvement.     

Climate as the dominant control on C3 and C4 plant abundance in the Loess Plateau： Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

Abundance of C3 and C4 photosynthesis plants can be inferred relatively from stable carbon isotopic composition of organic matter in soils. The samples from five sequences of the last glacial-interglacial loess-soil in the Chinese Loess Plateau have been measured for organic carbon isotopic ratios (613Corg). The organic carbon isotope data show that relative abundance (or biomass) of C4 plants was increased ca. 40% for each sampling site from the last glacial maximum (LGM) to Holocene optimum, and increased southeastward on the Loess Plateau during both periods of LGM and Holocene. Statistic analyses on the steady maximum δ^13Corg values of Holocene soils and modern climatic data from the Loess Plateau and Inner Mongolia indicate that the C4 plant abundance increases with increasing temperature and decreasing precipitation. The C4 plant abundance is related much closer with mean April temperature and precipitation than annual. These results lead us to deduce following conclusions. First, temperature is the major factor for control on variations in C4 plant abundance in the Loess Plateau from the last glacial to interglacial. In the absence of favorable temperature condition, both of low moisture and low atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants in the plateau. Second,δ^13Corg in the loess-paleosol sequences, as a proxy of the relative abundance of C4 plants in the Loess Plateau, could not be used as an indicator of changes in the summer monsoon intensity unless the temperature had changed without great amplitude. Since all C4 plants are grasses, finally, the increase of the C4 plants supports that forest has not been dominant in the ecosystem on the Loess Plateau during Holocene although precipitation and atmospheric CO2 were largely increased relative to those during LGM.     

Fluid mineralization of the Dajing Sn-polymetal deposit： Evidence from LA-ICP-MS analysis of individual fluid inclusions

LA-ICP-MS analyses on single fluid inclusions trapped in fluorite and quartz from the Sn-Cu orebody of the Dajing deposit and from the Sn ore-body of the Huanggangliang deposit were conducted to trace the source and evolution of Cu-rich and Sn-rich fluids in the Dajing deposit using the Rb/Sr and Sn/Cu ratios of the fluids. The results show that the Cu-rich fluids in the Dajing deposit, relatively rich in Na and probably derived from deep-seated basic magma, contain Cu several to several tens of times more than Sn, and Sr several to several tens of times more than Rb, while the Sn-rich fluids, relatively rich in K and probably derived from high level granitic magma, contain Sn several to several tens of times more than Cu, and Rb several to several tens of times more than Sr. It is suggested that the Sn-rich and the Cu-rich fluids were mixed at the stage of moderate to low temperature and low salinity, resulting in the formation of Cu-Sn orebodies at the central part of the Dajing deposit.     

Ramet population ecology of Panicum virgatum in the field —Competitively random growth of ramets and foraging behavior of ramet populations

The authors investigated the heterogeneous size patterns and dynamic growth of the ramet population of Panicum virgatum, a clonal caespitose plant, limited to the space occupied by a ramet bunch and the time of the ramet yearly life cycle, to understand the ecology of clonal caespitose plants in the field, where the ramet bunch generally consisted of more than one genet. Dynamic life tables for ramet populations were established by the replacement of living ramets at the present time with ＂dead＂ ones in past time. These tables revealed stable coexisting patterns of isometric and allometric growing processes of ramets in mass and height respectively, which approximately followed the historic trajectory of a density-independent population. The ecology of clonal caespitose plants is further discussed based on the competitively random growth of ramet individuals, including the scale of foraging behavior. In the field, the ramet population ecology of switchgrass may be a statistical result of competitively random growth of ramet individuals. The foraging behavior of a ramet population could then be presented as a process in which ramet individuals competed with each other for light and grew randomly, while at the same time a relatively stable dynamic growth pattern was apparent at the level of the ramet population, and the functional leaves were placed properly in time and space.     

A new mechanism of invader success： Exotic plant inhibits natural vegetation restoration by changing soil microbe community

Since the 1950s of the last century, the exotic plant, Eupatorium adenophorum, has spread rapidly across southwest China, damaging native ecosystems and causing great economic losses. We examined the pH, N, P, K, and organic matter concentrations, and the bacterial community character (by Biolog EcoPlateTM) in soils from sites heavily and lightly invaded by this exotic species. Also, soil from the lightly invaded site was treated with a water extract of E.adenophorum roots to examine the effect of the plant on soil properties. We grew three plant species, one native and two exotic, in pot experiment using soil from heavily invaded site to examine the effects of the soil on these plants growth. The soil analysis demonstrated that the pH, organic matter, total N, total P and total K in soils from the heavily invaded site were only slightly different from those of the lightly invaded site, but concentrations of NH4^ , NO3^- and available P and K in the heavily invaded site were greater than those in the lightly invaded site. The catabolic activity of soil bacterial community in the heavily invaded site was different from that in the lightly invaded site. The catabolic activity of bacterial community in soils treated by the water extract of E.adenophorum roots changed and became similar to that in soils from the heavily invaded site. The pot experiment showed that the exotic plants growth in heavily invaded soil were not different from in lightly invaded soil; however, the native plant biomass decreased dramatically when grown in soil from the heavily invaded site as compared to soil from the lightly invaded site; and the same phenomenon was found when any potential allelopathic effects by E. adenophorum were eliminated by added activated carbon to those soils. Difference in soil nutrient availability and allelopathy could not explain this phenomenon of the native plant in the soils from the heavily and lightly invaded sites. Changes observed in the soil bacterial community were obviously related to native plant growth in those tow soils. Those results suggest that changing soil microbial community may be an important part of E. adenophorum invasion process. Since the soil microbial community serves as bridge in connection of exotic and natural plants, the exotic plant could inhibit the natural plant growth and reproduction by changing the soil microbial community in invaded site.     

Studies on the changes of West Lake＇s zoobenthic communites after Qiantang River water was pumped into it

During Jan. 1995 to Dec. 1996, monthly investigations on the zoobenthic conummities of West Lake, samples were collected from six sampling stations. A total of 26 species of macmzoobenthes were identified. The seasonal changes in density and biomass of zoobenthos in this lake were analyzed. The annual mean densities were 980- 2751 ind/m^2 and mean biomass was 19.69 - 122.80 g/m^2. The densities in winter and early spring were higher than those in sumr~r and autunm. Comimrafive study of theprevious data ( 1982 to 1983) collected by the authors, showed that the succession of zoobenthic conammities, dominated by Procludius choreus in density and Bellamya purificata in biomass, had been occurred in Xiaonan sub-lake after Qiantang River water was drawn into it; and that the species and biomass of zoobenthes were then increased and the density was decreased. In other sub-lakes, the dominant species were Limnodrilus hoffmeisteri and Tokunag-ayusurika akamusi in density and Branchiura sowerbyi and Tokunagayusurika akamusi in biomass. The water quality was bad in these sub-lakes because these dominant species are indicators of eutrophication. According to the Margalef index and Goodnight index, West Lake is still an eutrophic lake. Only the water quality of Xiaonan sub-lake was improved after water drawn from the Qiantang River was introduced into it.     

Pb uptake, accumulation, subcellular distribution in a Pb－accumulating ecotype of Sedum alfredii （Hance）

Lead concentrations in roots, stems and leaves of accumulating and non-accumulating ecotypes of Sedum alfredii (Hance) were studied through a hydroponic experiment with different Pb concentrations sup-plied as Pb( NO3 )2 .Lead concentrations in leaves and stems of the accumulating ecotype were 4-9 times and 3-5 times those of the non-accumulating ecotype, and Pb-accumulated amounts in stems and leaves of theaccumulating ecotype were 4-9 times and 8-1l times higher than those of the non-accumulating ecotype,respectively. The results indicated that the accumulating ecotype had better ability to transport Pb from roots toshoots. The subeellular distributions of Pb in the root, stem and leaf tissues were studied using sucrose differ-ential centrifugation. Approximately 50% of Pb contents was found to be associated with the cell wall fractionin stems of the accumulating ecotype and the percentage increased to 80％ both in roots and leaves, no matter when plants were grown with different levels of Pb. The results indicated that the distribution of Pb on cell walls of the accumulating ecotype could mainly account for the high tolerance to Pb.     

Population dynamics and spatial distribution of microbial species in multispecies biofilms under the action of direct electric current

The metabolism, population dynamics and spatial distribution of nitrifying bacteria and heterotrophs in biofilms under the action of direct electric current were investigated by using the micro-slicing technique. The nitrification rate of nitrifying bacteria was severely inhibited by a current over 10 Am^-2 at lower C/N ratios. Compared to heterotrophs, the nitrifying bacteria in the surface biofilms were severely inhibited, resulting in a significant decrease in bacterial density. An increase in current density narrowed the less current-sensitive inner biofilm region, and in addition the density of NO2-oxidizers decreased more significantly than that of NH4-oxidizers in the surface biofilms probably due to electrochemical reactions at the anode. However, the effect of current on both the population dynamics and the spatial distribution of the microbial species was less significant at larger C/N ratios.     

Supergravity separation of Pb and Sn from waste printed circuit boards at different temperatures

Printed circuit boards (PCBs) contain many toxic substances as well as valuable metals, e.g., lead (Pb) and tin (Sn). In this study, a novel technology, named supergravity, was used to separate different mass ratios of Pb and Sn from Pb-Sn alloys in PCBs. In a supergravity field, the liquid metal phase can permeate from solid particles. Hence, temperatures of 200, 280, and 400℃ were chosen to separate Pb and Sn from PCBs. The results depicted that gravity coefficient only affected the recovery rates of Pb and Sn, whereas it had little effect on the mass ratios of Pb and Sn in the obtained alloys. With an increase in gravity coefficient, the recovery values of Pb and Sn in each step of the separation process increased. In the single-step separation process, the mass ratios of Pb and Sn in Pb-Sn alloys were 0.55, 0.40, and 0.64 at 200, 280, and 400℃, respectively. In the two-step separation process, the mass ratios were 0.12 and 0.55 at 280 and 400℃, respectively. Further, the mass ratio was observed to be 0.76 at 400℃ in the three-step separation process. This process provides an innovative approach to the recycling mechanism of Pb and Sn from PCBs.     

Analysis of the formation conditions and characteristics of interphase and random vanadium precipitation in a low-carbon steel during isothermal heat treatment

The characteristics of nanosized precipitates in steels depend on the heat-treatment parameters. The effects of characteristics of vanadium precipitates formed during isothermal heat treatment on the hardness of the ferrite matrix in low-carbon vanadium-alloyed steel were investigated through analysis of transmission electron microscopy images and microhardness measurements. The results show that, during isothermal holding in the temperature range from 675 to 750℃, only interphase precipitation occurs, whereas only random precipitation occurs in the ferrite matrix during holding at 600℃. Furthermore, during isothermal heat treatment between 600 and 675℃, both random and interphase precipitates occurred in the ferrite. Nanoscale vanadium carbides with different atomic ratios of vanadium (V) and carbon (C) were the dominant precipitates in the random and interphase precipitates. The sizes of random precipitation carbides were smaller than those of interphase ones. Also, the sample isothermally heat treated at 650℃ for 900 s exhibited a higher hardness with a narrower hardness distribution.     

Seasonal variation of global stratosphere-troposphere mass exchange

By Wei formula in pressure coordinate, the stratosphere-troposphere mass exchange (STME) is diagnosed globally for 44 years from 1958 to 2001 using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis datasets. Regions of mass flux into the stratosphere are found over Indonesia, bay of Bangladesh and the mid-west coast of South Africa. Compensating mass outflow from the stratosphere appears mainly over mid-latitudes near large-scale troughs. Upward and downward transport of mass at the middle and high latitudes accompany with each other. Mass flux into troposphere is stronger in autumn and winter than in spring and summer. Strong downward mass flux into the troposphere occurs in eastern Asia the whole year with nearly stable sites. Although the area of eastern Asia accounts for only 5.6% of that of the northern hemisphere (NH), its net mass exchange reaches 15.83% of that of the NH, which means that research on STME of eastern Asia is greatly important to that of the NH and even the global areas. Air across the tropopause enters more from stratosphere to troposphere than that from troposphere to stratosphere, which is possibly related with systematic bias of the assimilated datasets and with persistent rise of the tropopause height. Contributions of the mass exchange and the mass flux exchange in the NH and southern hemisphere (SH) on their latitudes increase from equator to pole, with larger contributions in the NH. Mass exchange and mass flux exchange per areas at high latitudes are larger than that at low latitudes, which means greater mass exchange efficiency at high latitudes.     

Dynamic mass variation and multiphase interaction among steel,slag, lining refractory and nonmetallic inclusions: Laboratory experiments and mathematical prediction

The mass transfer among the multiphase interactions among the steel, slag, lining refractory, and nonmetallic inclusions during the refining process of a bearing steel was studied using laboratory experiments and numerical kinetic prediction. Experiments on the system with and without the slag phase were carried out to evaluate the influence of the refractory and the slag on the mass transfer. A mathematical model coupled the ion and molecule coexistence theory, coupled-reaction model, and the surface renewal theory was established to predict the dynamic mass transfer and composition transformation of the steel, the slag, and nonmetallic inclusions in the steel. During the refining process,Al_2 O_3 inclusions transformed into Mg O inclusions owing to the mass transfer of [Mg] at the steel/refractory interface and(Mg O) at the slag/refractory interface. Most of the aluminum involved in the transport entered the slag and a small part of the aluminum transferred to lining refractory, forming the Al_2 O_3 or Mg O·Al_2 O_3. The slag had a significant acceleration effect on the mass transfer. The mass transfer rate(or the reaction rate) of the system with the slag was approximately 5 times larger than that of the system without the slag. In the first 20 min of the refining, rates of magnesium mass transfer at the steel/inclusion interface, steel/refractory interface, and steel/slag interface were x, 1.1 x, and 2.2 x,respectively. The composition transformation of inclusions and the mass transfer of magnesium and aluminum in the steel were predicted with an acceptable accuracy using the established kinetic model.     

Subsurface macro-inclusions and solidified hook character in aluminum-killed deep-drawing steel slabs

Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ultralow carbon (ULC) steel slabs and two low carbon (LC) aluminum-killed steel slabs were sampled to study the relationship between hooks and subsurface macro-inclusions, which were detected on the cross-sections of steel samples with an area of 56058 mm2 using an automated scanning electron microscopy/energy-dispersive X-ray spectroscopy system. Results show that subsurface inclusions larger than 200 μm were almost entrapped by hook structures, whereas the location of other inclusions smaller than 200 μm had no obvious dependence on the location of solidified hooks. Furthermore, the number density (ND) of subsurface inclusions larger than 200 μm decreased from 0.02 to 0 cm-2 in ULC steel as the mean hook depth decreased from 1.57 to 1.01 mm. Similar trends were also observed in LC steel. In addition, the detected inclusions larger than 200 μm were concentrated in the region near the slab center (3/8 width-5/8 width), where hook depths were also larger than those at any other locations. Therefore, minimizing the hook depth is an effective way to reduce inclusion-induced sliver defects in deep-drawing steels.     

Behavioral and olfactory responses of grasshopper hatchlings,<Emphasis Type="Italic">Melanoplus sanguinipes</Emphasis>, to plant odours and volatile compounds

Behavior and olfactory responses of grasshopper hatchlings, Melanoplus sanguinipes (F.), to odours from plant foliage and volatile compounds were tested using a glass Y-tube olfactometer and electroantennogram (EAG)techniques respectively. In single choice trials, newly hatched hoppers were much more sensitive to the odour from intact leaves and chopped foliage of ryegrass and wheat than other plants. Chopped sorghum leaves, but not stem-cut sorghum,were also significantly attractive. The orientation responses of grasshopper hatchlings to these plants were highly consistent with those of last instar hoppers and adults. When ryegrass was employed as the control, the odour from stem-cut alfalfa was more attractive. There was no significant difference in hopper orientation responses to the odours from chopped seedlings of sorghum, alfalfa, wheat or ryegrass.However, significantly more hoppers preferred the chopped ryegrass control to chopped Louisanna sage. Measurement of the EAG response of first instar hoppers to these plant odours showed that the odour of Louisanna sage elicited the greatest response amplitudes. In olfactory tests using different volatile components, Z-3-hexenol, E-3-hexenol,Z-hex-3-enyl acetate, E-2-hexenal and hexenal gave greater EAG responses than geraniol and 1-octen-3-ol. These results are also consistent with comparable data from adults. Newly hatched grasshoppers had similar EAG response profiles to plant materials and chemicals to those of adults, although the absolute EAG values of young hoppers were much lower than those of adults. Therefore, newly hatched hoppers were able to distinguish plants from an air control, and even host plants from non-host plants, and the feeding experience of hoppers probably has little influence on their subsequent ability as adults to identify and locate food plants.