2种高分子保水材料对土壤持水能力的影响

采用离心机法,研究聚丙烯酸钠与聚丙烯酰胺2种高分子化合物在5种使用浓度(占干土质量0、0.01%、0.08%、0.2%与1%)的条件下对3种土壤(砂土、壤土、黏土)持水能力的影响。结果表明:3种土壤在0.01~1.5MPa水吸力时,持水能力随着2种高分子材料用量的增加而增加,砂土的作用效果较壤土、黏土更显著;2种高分子材料与土壤质量比控制在8/10000~2/1000范围内其作用效果较好,该用量条件下高分子吸持水分平均可释放83.7%供植物吸收利用。2种高分子材料对土壤持水能力的作用效果基本相同。

不同水分状况下秸秆覆盖量对玉米根、冠生长的影响

在遮雨棚控水条件下,采用盆栽的方式研究了不同秸秆覆盖量对玉米根、冠生长的影响。试验按对照(CK)和秸秆覆盖量0.3 kg/m2(SM0.3)、0.6 kg/m2(SM0.6)、0.9 kg/m2(SM0.9)、1.2 kg/m2(SM1.2)共设5个处理,水分按高水(占田间持水量的90%)和低水(占田间持水量的60%)设两个水平。分别测定了玉米根、茎、叶、穗干重,根系垂直空间分布及叶片叶绿素相对含量等指标。结果表明:秸秆覆盖明显改变了玉米根系和地上部分的生长;高水条件下SM0.6处理玉米根系、茎秆、叶和穗干重均高于其它处理;低水条件下,地上部分干重SM1.2最大,SM0.6次之;根系的垂直空间分布与水分和覆盖条件都有密切的关系,覆盖措施主要影响下层根系的生长和发育。

四种园林植物的热值与养分特征

测定了蔷薇科植物美人梅、樱花和木兰科植物白玉兰、广玉兰不同组分的热值、养分和灰分含量,探讨4种植物不同发育阶段根系、枝干和叶等器官的热值分配特征及其影响因子.结果表明:4种植物不同组分干质量热值和去灰分热值在17.02~21.93 kJ.g-1和18.42~22.57 kJ.g-1之间;叶片和细根具有较高的干质量热值和去灰分热值,去灰分热值随着根系和茎干(枝)的发育呈减小趋势.美人梅和樱花的干质量热值和去灰分热值总体上高于白玉兰和广玉兰.细根干质量热值和去灰分热值与其养分和灰分含量呈极显著相关(P<0.01).随着根系的发育,干质量热值和去灰分热值与有机碳含量的相关性逐渐降低,不同器官干质量热值与全氮含量相关性最强.

容器苗质量评定指标的研究

In this paper,the assessing indices of container seedlings quality were synthesized in accordance with growth and physiological factors. The results showed that the seedling quality might be determined by the dormancy state of terminal bud,nutrient condition of plant,and the state of root system. The critical quality indices should include stem diameter at soil surface,dry weight of terminal bud,and soluble sugar content. Moreover,some indices such as root system vitality and dry weight of plant were also important.

Antioxidative principals of Jussiaea repens: an edible medicinal plant

Jussiaea repens L. (JRL) is an edible medicinal plant and is also used as a vegetable by the local people in southwestern China. The crude extract and its four fractions derived from JRL were evaluated for the 1,1-diphenyl-2-picrylhydrazyl radical-scavenging ability, hydroxyl radical-scavenging capacity and the potassium ferricyanide reduction property. The ethyl acetate-soluble fraction (EAF) and EAF6 (a subfraction derived from EAF) were the most valuable fraction and subfraction, respectively. Furthermore, bioactivity-guided chromatographic fractionation revealed that three pure compounds greatly contributed to the antioxidant activities. Qualitative and quantitative analyses of the major antioxidant constituents in the extract were systematically conducted by NMR, mass spectral analyses and RP-HPLC. The result demonstrated that rosmarinic acid (2.00 mg g(-1) JRL dry weight) quercetin 3-O-beta-D-glucopyranoside (9.88 mg g(-1) JRL dry weight), and kaempferol 3-O-beta-D-glucopyranoside (1.85 mg g(-1) JRL dry weight) were the major antioxidative constituents in JRL. These compounds are reported for the first time from this plant.

ISOLATION AND CHARACTERIZATION OF CHLORELLA SOROKINIANA GXNN01 (CHLOROPHYTA) WITH THE PROPERTIES OF HETEROTROPHIC AND MICROAEROBIC GROWTH

Heterotrophic and anaerobic microalgae are of significance in both basic research and industrial application. A microalga strain was isolated from a wastewater treatment pond and identified as Chlorella sorokiniana Shihira et W. R. Krauss GXNN01 in terms of morphology, physiology, and phylogeny. The strain grows rapidly in heterotrophic or mixotrophic conditions with addition of various carbon sources, and even in anaerobic conditions. The maximum growth rate reached 0.28 d(-1) when using D,L-malate as the carbon source, and the protein content of the microalgae was 75.32% in cell dry weight. The strain was shown to be capable of (1) utilizing D, L-malate only with light, (2) inhibiting photosynthesis in mixotrophic growth, and (3) growing in anaerobic conditions with regular photosynthesis and producing oxygen internally. This study demonstrates the influence of oxygen (aerobic vs. anaerobic) and metabolic regime (autotrophy, mixotrophy, heterotrophy) on the physiological state of the cell.

Effect of carbon source on growth and lipid accumulation in Chlorella sorokiniana GXNN01

Heterotrophic culture of microalgae to develop methods of increasing biomass productivity and storage lipids has brought new insight to commercial biodiesel production. To understand the relationship between heterotrophy and lipid production, the effects of carbon sources on the growth and lipid accumulation of Chlorella sorokiniana GXNN01 was studied. The alga exhibited an increased growth rate in response to the addition of carbon sources, which reached the stationary phase after 48 h at 30A degrees C. In addition, glucose and NaAc had a significant effect on the lipid accumulation during the early-stationary phase. Specifically, the lipid content was 0.237 +/- 0.026 g g(-1) cell dry weight and 0.272 +/- 0.041 g L-1 when glucose was used as the carbon source, whereas the lipid content reached 0.287 +/- 0.018 g g(-1) cell dry weight and 0.288 +/- 0.008 g L-1 when NaAc was used as the carbon source. The neutral lipid content was found to first decrease and then increase over time during the growth phase. A glucose concentration of 20 mmol L-1 gave the maximal lipid yield and the optimum harvest time was the early-stationary phase.

Translocation of assimilates in Undaria and its cultivation in China

Undaria cultivation on a commercial scale began in China only in the last decade. Today, Undaria pinnatifida is the main species under cultivation concentrated in two provinces, Liaoning and Shandong. The annual production in the early nineties was 8000-13 000 tons dry weight, which is two or three times the pre-1980 figures. The raft cultivation method maintaining the alga at the desired depths generally ensures the light saturated rate of photosynthesis on clear days, and enhances production. Under the cultivated condition, the calculated annual primary productivity of this alga is 160 g C m(-2) y(-1). Translocation of C-14-labelled photoassimilates in rapidly growing sporophyte of Undaria pinnatifida was studied in the open sea. Samples from different parts of the blade with counterparts exposed to tracer ((NaHCO3)-C-14) showed that the translocation that occurred mainly from the tip of the blade to the growing region had obvious source-sink relationship. It took 20 minutes to translocate the labelled photoassimilates from the epidermis, via cortex, to the medulla of the midrib, where rates of translocation averaging 42-48 cm h(-1) were observed in the open sea. Production experiments of tip-cutting of the blades showed an increased production of 9%.

Effect of iron on growth and lipid accumulation in Chlorella vulgaris

The economic feasibility of algal mass culture for biodiesel production is enhanced by the increase in biomass productivity and storage lipids. Effect of iron on growth and lipid accumulation in marine microalgae Chlorella vulgaris were investigated. In experiment I, supplementing the growth media with chelated FeCl3 in the late growth phase increased the final cell density but did not induce lipid accumulation in cells. In experiment II, cells in the late-exponential growth phase were collected by centrifugation and re-inoculated into new media supplemented with five levels of Fe3+ concentration. Total lipid content in cultures supplemented with 1.2 x 10(-5) mol L-1 FeCl3 was up to 56.6% biomass by dry weight and was 3-7-fold that in other media supplemented with lower iron concentration. Moreover, a simple and rapid method determining the lipid accumulation in C. vulgaris with spectrofluorimetry was developed. (c) 2007 Elsevier Ltd. All rights reserved.

Evaluation of 28 marine algae from the Qingdao coast for antioxidative capacity and determination of antioxidant efficiency and total phenolic content of fractions and subfractions derived from Symphyocladia latiuscula (Rhodomelaceae)

The extracts obtained from 28 species of marine algae were evaluated for their antioxidant activity (AA) versus the positive controls butylated hydroxytoluene (BHT), gallic acid (GA), and ascorbic acid (AscA). Most of the tested samples displayed antioxidant activity to various degrees. Among them, the extract of Symphyocladia latiuscula exhibited the strongest AA, which was comparable to BHT, GA, and AscA in radical scavenging activity, as shown in the DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) assay, and higher than those of the positive controls in beta-carotene-linoleate assay system. In addition, the ethyl acetate-soluble fraction isolated from the crude extract of S. latiuscula exhibited the highest antioxidant activity in both assay systems. This fraction was further fractionated into seven subfractions (F1-F7) by vacuum liquid chromatography (VLC). F1 and F4 were found to be the most effective subfractions in scavenging DPPH radical assay and in the beta-carotene-linoleate assay, respectively. The total phenolic content (TPC) and reducing power (RP) for all of the extracts, fractions, and subfractions (F1-F7) were also determined. The TPC of the 28 extracts ranged from 0.10 to 8.00 gallic acid equivalents (mg/g seaweed dry weight) while the RP ranged from 0.07 to 11.60 ascorbic acid equivalents (mg center dot g(-1) seaweed dry weight). Highly positive relationships between AA and TPC as well as between AA and RP were found for the extracts and fractions, while for the subfractions F1-F7 only weak or no such relations were found. The results obtained from this study indicate that further analysis is needed of those marine algal species that contain the most antioxidant activity in order to identify the active principles.

There are two 5 '-flanking regions of bkt encoding beta-carotene ketolase in Haematococcus pluvialis

The unicellular green alga Haematococcus pluvialis accumulates a commercially valuable astaxanthin, with levels reaching up to 4% dry weight under environmental stress. In recent years, much effort has been devoted to understanding the molecular mechanisms regulating astaxanthin biosynthetic pathways. Beta-carotene ketolase (bkt), with control being exhibited at the transcription level, plays an important role in astaxanthin biosynthesis by H. pluvialis. Here we demonstrate the presence of two separate 5'-flanking regions [1.5 kilobase (kb) and 2 kb] of bkt (bkt1 and bkt2) that possess regulatory elements similar to those of known stress-responsive genes in plants. Results of 5'-deletion constructs and transient beta-galactosidase expression assays demonstrate that there may be positive regulatory elements governing expression in the shorter promoter at -1060/-900 from the 1.5 kb 5' region, and in the longer promoter at -1838/-1219 and at -1046/ -734 from the 2 kb 5' region relative to each homologous ATG start codon. Furthermore, our present studies reveal that the first intron (+371/+497) downstream from the 1.5 kb 5' untranslated region of bkt1 may function as a negative regulatory element to regulate its own promoter.

Optimization of conditions for cell cultivation of Porphyra haitanensis conchocelis in a bubble-column bioreactor

Process conditions for cell cultures derived from conchocelis of female red macroalga Porphyra haitanensis were optimized in an illuminated 0.3-l bubble-column photobioreactor, using CO2 in air as the sole carbon source during a 20-day cultivation period. It reached the highest growth rate when the initial cell density was 700 mg l(-1)(dry weight), the optional aeration rate was 1.2 v/v/min, inorganic nitrate concentration was 15 mM and inorganic phosphate concentration was 0.6 mM. This is the first reported bioreactor cultivation study of cell cultures derived from conchocelis of Porphyra haitanensis.

Black carbon and polycyclic aromatic hydrocarbons (PAHs) in surface sediments of China's marginal seas

This study investigates the distribution of black carbon (BC) and its correlation with total polycyclic aromatic hydrocarbons (I PAH) pound in the surface sediments of China's marginal seas. BC content ranges from < 0.10 to 2.45 mg/g dw (grams dry weight) in the sediments studied, and varied among the different coastal regions. The Bohai Bay sediments had the highest BC contents (average 2.18 mg/g dw), which comprises a significant fraction (27%-41%) of the total organic carbon (TOC) preserved in the sediments. In comparison, BC in the surface sediments of the North Yellow Sea, Jiaozhou Bay, East China Sea and the South China Sea is less abundant and accounted for an average of 6%, 8%, 14% and 5%, respectively, of the sedimentary organic carbon pool. The concentration of I PAH pound in the surface sediments ranges from 41 to 3 667 ng/g dw and showed large spatial variations among the sampling sites of different costal regions. The Bohai Bay has the highest I PAH pound values, ranging from 79 to 3 667 ng/g dw. This reflects the high anthropogenically contaminated nature of the sediments in the bay. BC is positively correlated to TOC but a strong correlation is not found between BC and I PAH pound in the surface sediments studied, suggesting that BC and PAHs preserved in the sediments are derived from different sources and controlled by different biogeochemical processes. Our study suggests that the abundance of BC preserved in the sediments could represent a significant sink pool of carbon cycling in China's marginal seas.

Preservation of black carbon in the shelf sediments of the East China Sea

Concentrations and carbon isotopic (C-14, C-13) compositions of black carbon (BC) were measured for three sediment cores collected from the Changjiang River estuary and the shelf of the East China Sea. BC concentrations ranged from 0.02 to 0.14 mg/g (dry weight), and accounted for 5% to 26% of the sedimentary total organic carbon (TOC) pool. Among the three sediment cores collected at each site, sediment from the Changjiang River estuary had relatively high BC contents compared with the sediments from the East China Sea shelf, suggesting that the Changjiang River discharge played an important role in the delivery of BC to the coastal region. Radiocarbon measurements indicate that the ages of BC are in the range of 6910 to 12250 years old B. P. (before present), that is in general, 3700 to 9000 years older than the C-14 ages of TOC in the sediments. These variable radiocarbon ages suggest that the BC preserved in the sediments was derived from the products of both biomass fire and fossil fuel combustion, as well as from ancient rock weathering. Based on an isotopic mass balance model, we calculated that fossil fuel combustion contributed most (60%. 80%) of the BC preserved in these sediments and varied with depth and locations. The deposition and burial of this "slow-cycling" BC in the sediments of the East China Sea shelf represent a significant pool of carbon sink and could greatly influence carbon cycling in the region.

Growth, survival and immune activity of scallops, Chlamys farreri Jones et Preston, compared between suspended and bottom culture in Haizhou Bay, China

We examined the growth, survival and immune response of the scallop, Chlamys farreri, during a 1-year period in deep water of Haizhou Bay. Scallops were cultured using two methods: (1) in lantern nets at a 5 m depth and (2) in a bottom culture system (sleeves) on the seabed at about a 25 m depth. Shell heights, meat dry weight and immune activities in the haemolymph (superoxide dismutase and myeloperoxidase) were measured bimonthly or quarterly from July 2007 to June 2008. Survival was measured at the end of the study and environmental parameters in the experimental layers were monitored during the experiment. The growth and immune activities of scallops were lower when the water temperature was high, which was consistent with the main mortality occurring in summer. The growth and immunity of scallops were higher in the suspended culture than in the bottom culture during the experiment, with the exception of shell growth during the last study period. Survival of scallops in the suspended culture (54.6 +/- 12.3%) was significantly lower than that in the bottom culture (86.8 +/- 3.5%) at the end of this study. We conclude from our results that the high mortality of C. farreri can be prevented by culturing them in a bottom culture system before November of the first year, and then transferring them to a suspended culture to improve scallop production.