喜树幼苗的硝酸还原酶活性及其日变化规律

本文利用体内法测定了喜树幼苗不同器官以及不同叶位叶片的硝酸还原酶活性(NRA),同时观察了喜树幼苗不同叶位叶片的NRA的日变化规律,并考查了NRA与叶面积及比叶重的相关性。结果表明,与根、茎及茎尖中的NRA相比,叶片中的NRA最高。不同叶位叶片的NRA有明显的差异,在所测定的10个不同叶位的叶片中,上数第4~6片叶片的NRA较高。叶片NRA有明显的日变化,呈单峰曲线,峰值出现在中午1230前后。同时,结果表明NRA与叶面积以及比叶重无明显的相关关系。研究结果为进一步研究喜树的氮代谢提供基础资料。图5参18。     

Effect of planting density on plant growth and camptothecin content of Camptotheca acuminata seedlings

C. acuminata seedlings cultivated in greenhouse were transplanted into the fields with 5 designed planting densities (11, 16, 25, 44 and 100 plants·m⁻²) in May of 2004 and were harvested in the middle of September of 2004. The seedling growth indexes including plant height and crown width, biomass allocation, camptothecin (CPT) content and CPT yield of different organs (young leaf, old leaf, stem, and root) were studied. For the 5 selected planting densities, the plant biomass, height, crown width, and total leaf area ofC. acuminata seedlings all showed highest values at the planting density of 25 plants·m⁻². CPT content in young leaves was higher than that in other organs of seedlings and presented an obvious change with the variation of planting densities and with the highest value at density of 100 plants·m⁻², while for other organs no significant variation in CPT content was found with change of planting density. The accumulation of CPT was enhanced significantly at the planting density of 25 plants·m⁻². It is concluded that for the purpose to get raw materials with more CPT fromC. acuminata, the optimal planting density ofC. acuminata seedlings should be designed as 25 plants·m⁻². Foundation item: This paper was supported by the National Natural Science Foundation of China (No. 3970086) and Heilongjiang Province Foundation for Distinguished Youth Scholars (JC-02-11) Biography: Wei Huan-yong (1978-), male, Graduate in College of Life Sciences, Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

Nutrient element contents of cutting seedlings of hybrid species （ Liriodendron chinense x tulipifera）

The cutting seedlings ofLiriodendron chinense xtulipifera were treated with the different concentrations of auxin (treatment₁: IBA of 50 g·kg⁻¹+NAA of 300 g·kg⁻¹; treatment₂; IBA of 100 g·kg⁻¹+NAA of 300 g·kg⁻¹). The biomass nutrient element contents for different organs (root, stem, leaf) of cutting seedling ofLiriodendron chinense xtulipifera were measured by the dry method, Kjeldahl method and Atomic Absorption Spectroscopy method. The result showed that the biomass of root, stem, and leaf of the cutting seedling treated with auxin was all remarkably increased. The contents of element C in root, stem and leaf had no significant difference between the control and auxin treatments, while the contents of N, P, K and Ca in stem were much lower than that in leaf and root. Variance analysis showed that for the same organ with different concentration treatment of auxin, the four nutrient elements (N, P, K, and Ca) had no significant difference in contents, while there existed significant or very significant difference in contents of the four nutrient elements in different organs with the same concentration auxin treatment. The N, P, K and Ca contents were very low in cutting seedlings; as a result, additional fertilizer should be applied to the seedlings when they were planted in the field. Foundation item: This paper was supported by Jiangsu Province Science Foundation (BE96350). Biography: ZHANG Xiao-ping, (1972-), female, Ph. Doctor in Nanjing Forestry University. Nanjing 210037, P. R. China. Responsible editor: Zhu Hong     

Responses of fractal dimensions ofPicea koraiensis seedlings to different light environments

The changes of fractal dimension ofPicea koraiensis seedlings under different light intensities in natural secondary forests was studied. The results showed that with the change of light environment, crown characters ofPicea koraiensis seedlings exhibited a greater plastic in lateral number, lateral increment, lateral dry weight, and specific leaf area. The range of calculated fractal dimensions of seedling crowns was confined between 2.5728 and 2.1036, but maximum of fractal dimension achieved in term moderate shading and in extreme low light conditions fractal dimension was least. Foundation item: This paper was supported by the National Natural Science Foundation of China (No.39670152) and Chinese Academy of Sciences. Biography: ZHOU Yong-bin (1970-), female, Ph. Doctor, lecture in Shenyang Agricultural University, Shenyang 110161, P.R. China Responsible editor: Song Funan     

Leaf conductance of primary and mature leaves ofPinus roxburghii: A comparison

We used a null-balance porometer to measure leaf conductance of mature and primary leaves of natural seedlings, saplings, and trees ofPinus roxburghii (chir) during autumn at four sites at 1,320–1,930 m elevation in the central Himalaya of India. Our hypothesis that primary leaves had higher leaf conductance than mature leaves (needles in fascicles), based on measurements in other pines, was rejected. Comparisons on the same saplings and seedlings showed lower leaf conductance for primary leaves than for mature leaves. Primary leaves on seedlings and saplings also did not consistently have higher leaf conductance than mature leaves on near-by trees. Mature leaves on seedlings, however, did often have higher conductance than mature leaves on nearby trees. Mean values for leaf conductance (mmol m⁻² s⁻¹, based on total leaf surface area) ranged from 42–82 for mature leaves on trees, 60–121 for mature leaves on seedlings, and 28–67 for primary leaves on seedlings. Compared to published values for other pine species, conductance of mature leaves ofP. roxburghii is relatively low. Funding for this study was provided by grants from the United States National Science Foundation, INT-9312052 and INT-9404043. We appreciate the review of an early draft by Barbara Bond.     

Assessment of factors affectingin vitro shoot regeneration from axillary bud explant ofCamptotheca acuminata

Axillary buds from 3-yr.-old seedlings ofCamptotheca acuminata in the greenhouse were cultured on the different basal media with different concentrations of growth regulators for shoot regeneration for studying the effects of different basal media, different concentrations of growth regulators (BA or TDZ), sucrose, agar and pH value on shoot regeneration from axillary bud. The results showed that B5 and WPM media were the optimal basal media and the optimal phyotohormone was BA of 1.0 mg/L or TDZ of 0.1 mg/L; The concentrations of sucrose of 30g/L and agar of 6g/L were most suitable for the shoot regeneration; pH value from 5.8 to 6.6 were broadly effective, but the best at pH 5.8. Foundation item: The research was supported by the Key Project of Chinese Ministry of Education (03061) and Supported by Application Fund of Agricultural Research Production (03EFN216700297). Biography: Wang Hui-mei (1973-), female, Ph.D., Lecturer in Northeast Forestry University, Harbin 150040, P.R. China. Responsible editor: Zhu Hong     

Adaptive responses of<Emphasis Type="Italic">Acer ginnala,Pyrus ussuriensis and Prunus davidiana</Emphasis> seedlings to soil moisture stress

One-year-old seedlings of Amur maple (Acer ginnala Maxim), Ussurian pear (Pyrus ussuriensis Maxim) and David peach (Prunus davidiana Carr) were planted in pots in greenhouse and treated with four different soil moisture contents (75.0%,61.1%, 46.4% and 35.4%). The results showed that net photosynthesis rate (NPR), transpiration rate (TR) and stomatal conductance (Sc) of seedlings of the three species decreased with the decease of soil moisture content, and Amur maple seedlings had the greatest change in those physiological indices, followed by Ussurian pear, David peach. Amur maple and Ussurian pear seedlings also presented a decrease tendency in water use efficiency (WUE) under lower soil moisture content, whereas this was reversed for David peach. Under water stress the biomass allocation to seedling root had a significant increase for all the experimental species. As to root/shoot ratio, Amur maple seedlings had the biggest increase, while David peach had the smaliest increase. The leaf plasticity of Amur maple seedlings was greater, the leaf size and total leaf area decreased significantly as the stress was intensified. No significant change of leaf size and total leaf area was found in seedlings of Ussurian pear and David peach. It was concluded that Amur maple was more tolerant to soil moisture stress in comparison with David peach and Ussurian pear.     

Callus induction from leaves of differentpaulownia species and its plantlet regeneration

The experiment was carried out on five different species ofPaulownia for callus induction from leaves. MS medium was adopted as basic medium, and from different combinations of NAA and BA the suitable media were determined for callus induction, bud differentiation, and root differentiation of five different species. MS+0.5NAA+4BA, MS+0.3NAA+2BA, MS+0.5NAA+4BA, MS+0.3NAA+6BA, and MS+0.3NAA+8BA were suitable media of callus inductions of leaves, respectively, forPaulownia tomentosa, Paulownia australis, Paulownia fortunei, Paulownia elongata andP. tmentosa x P. fortunei, and MS+0.3NAA+12BA, MS+0.3NAA+12BA, MS+0.5NAA+12BA, MS+0.5NAA+12BA, and MS+0.7NAA+12BA were suitable media for bud differentiation from leaf callus respectively for above five species. The rooting media was determined as 2MS+0.1NAA, 1/2MS+0.1NAA, 1/2MS, 1/2MS+0.3NAA, and 1/2MS+0.5NAA. These results provide reference data for breeding new fine varieties with different kinds ofPaulownia protoplasts fusions. Foundation Item: This paper was supported by National Nature Science Foundation of China (No. 39870631) and Nature Science Foundation of Henan Province (No. 994011100). Biography: Fan Guo-qiang (1964), male Ph. Doctor, Professor in Forestry Department of Henan Agriculture University. Zhengzhou 450002, P. R. China. E-mail: guoqiangf@263.net. Responsible editor: Song Funan     

Dynamic feature of flavonoids content in different organs of larch （Larix gmelinii）

Flavonoids in plants is very important in its ecological role and economic value. The dynamic features of flavonoids content in different organs of larch (Larix gmelinii) at different light and temperature conditions were investigated in this study. Results showed that the order of flavonoids content in different organs from high to low was 7.78% (stem bark)>2.79% (leaves) >1.72% (branches) >1.19% (stem xylem)and different organs had a great seasonal variation in flavonoids content, but the change of flavonoids content at different temperature was not obvious in different organs., The content of flavonoids in barck had, a positive correlation with temperature (R ²=0.75), but that in other organs had slight variation with the change of temperature. For all the tested organs, the flavonoids content in summer and autumn was approximately 3–4 times higher than in spring and winter. This is attributed to the great stress from environmental physical variables such as UV radiation, high temperature that induce the accumulation of flavonoids. The flavonoid content of sun leaves was evidently higher than that of shade leaves, and leaves at upper part of canopy had a higher flavonoids content compared with that at other parts. This result indicates that sun radiation could improve flavonoids production in leaves (R ²=0.76). The flavonoids may actively evolve in plant defenses to environmental stress, protecting larch from the damage of high temperature and radiation, and its main function is different in different organs. Foundation item: This paper is supported by the National Natural Science Foundation of China (30300271) and the Key Project of Chinese Ministry of Education (104191). Biography: WANG Wen-jie (1974-), male, Lecturer in Key Laboratory of Forest Plant Ecology, Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

Critical tidal level for forestation with hypocotyl of Rhizophora stylosa Griff along the Guangxi coast of China

From August 2004 to August 2005, three replicate experimental platforms were constructed in a section of the tidal flats in Yingluo Bay, Guangxi Province to study the growth and physiological responses of Rhizophora stylosa Griff seedlings to tidal waterlogging stress in a diurnal tidal zone. A total of eight tidal flat elevation (TFE) treatments, i.e., 320, 330, 340, 350, 360, 370, 380 and 390 cm above Yellow Sea Datum (YSD), were created on each platform. The results showed that lower TFEs (320–330 cm YSD) slightly increased the seedling stem height of 1-year old seedlings, while higher TFEs (>340 cm YSD) increased the seedling growth significantly. Moderate TFEs (350–370 cm YSD) favored the development of knots. Number of leaves, leaf conservation rate and leaf area per seedling all decreased dramatically with decreasing TFE. Lower TFEs caused large damage to Chl a, but Chl b was less affected. The Chl a/b ratio decreased with decreasing TFE. Prolonged waterlogging induced higher SOD activity in roots, while moderate TFE inhibited the SOD activity in leaves. The POD activity in roots and leaves increased with decreasing TFE. Waterlogging stress decreased the biomass of individual organs and entire seedlings. With increasing waterlogging, the biomass partitioning in 1-year old seedlings increased from leaf to stem. The survival rate decreased sharply from 88.9% to 40.0% as TFE decreased, while more than 80% of the seedlings were able to survive at the TFE level of 370 cm YSD and above. We propose that the local mean sea level should be adopted as the critical tidal level for forestation with hypocotyls of R. stylosa along the Guangxi coast.     

高效液相色谱法测定羟基喜树碱含量方法的研究

The determination method of 10-hydroxycamptothecin inCamptotheca acuminatu fruits by high-performance liquid chromatogram (HPLC) was studied. The HPLC analysis was performed on a HIQ sil C₁₈(4.6×250 mm) column with mobile phase of acetonitrile-water (3:7, V:V), flow rate 1 mL·min⁻¹ and UV detective wavelength 266 nm. Extracting 10-hydroxycamptothecin by ultrasonic method from fruits ofC. acuminata to prepare samples for analysis was systematically discussed. The optimal extraction condition was carried out by 60% alcohol solution at 60°C for 50 minutes. Foundation Item: This paper was supported by National Natural Science Foundation of China (No. 30070086). Biography: MA Mei-fang (1976-), female, Graduate Student of Northeast Forest University. Responsible editor: Song Funan     

3种木兰科植物叶片SPAD值的分布特征及其与叶绿素含量的关系

为探讨3种木兰科植物灰木莲Manglietia glauca、醉香含笑Michelia macclurei和乐昌含笑Michelia chapensis叶片SPAD值的分布特征及其与叶绿素含量之间的关系,采用SPAD叶绿素计和分光光度法分别测定了三者叶片SPAD值和叶绿素含量.结果表明:3种植物叶片SPAD值的差异主要...     

Evaluation of phytotoxic effects ofGliricidia sepium (Jacq.) Walp prunings on maize and cowpea seedlings

Phytotoxic effects ofGliricidia prunings were tested on maize seedlings in the laboratory and on maize and cowpea seedlings in the field. In the laboratory test, growth of maize seedlings was significantly depressed by addition of leachate ofGliricidia prunings. In the field, leaf, chlorosis of maize and cowpea seedlings occurred when mulched withGliricidia prunings; number of affected leaves increased with increasing mulch rate. Maize was more susceptible than cowpea. This phytotoxic effect, however, did not reduce growth of maize and cowpea seedlings in the field. ApplyingGliricidia mulch one week before planting eliminated the phytotoxic effects on maize.     

Diurnal change of gas exchange ofRhodiola sachalinensis transplanted from different habitats in Changbai Mountain

Rhodiola sachalinensis growing in the different habitats, such as Xiaotianchi plot (altitude 1800 m), Tree line plot (altitude 2000 m) and Tianwenfeng plot (altitude 2325 m) of Changbai Mountain (northern slop) were transplanted to Harbin Experimental Farm for determining its gas exchange. The study results indicated that the diurnal changes of gas exchange ofRh. sachalinensis transplanted from different habitats were still different though the morphological appearance of the newly sprouted above-ground part had become more similar. For net photosynthesis rate (Pn), stomatal conductance (Gs) and apparent quantum yield (AQY), the diumal change curves ofRh. sachalinensis transplanted from the three plots were similar, but the data value were different. For the dark respiration rate (Rd), transpiration rate (Tr) and water use efficiency (WUE), diurnal change curves of the three plots were obviously different. This study is supported by Natural Science Foundation of Heilongjiang Province. Yan Xiufeng, male, born in March 1965, associate professor, Open Research Laboratory of Forest Plant Ecology, Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

Homogenate extraction technology of camptothecine and hydroxycamptothecin from Camptotheca acuminata leaves

Camptothecine (CPT) and hydroxycamptothecin (HCPT), two kinds of anti-cancer alkaloids, were extracted from Camptotheca acuminata leaves using homogenate extraction technology under different conditions such as the ratio of material to liquid, ethanol concentration, and homogenate time. The optimum technology parameters for homogenate extraction of CPT and HCPT from C. acuminata leaves were determined as homogenate time at 8 min, ethanol concentration at 55% and the ratio of material to liquid at 1:15 (g:mL). By using the optimized parameters, we obtained 0.639‰ extraction rate for CPT and 0.437‰ for HCPT. The extraction yields of CPT and HCPT extracted by homogenating technology were higher than those by other extractive methods, such as ultrasonic, reflux, shaking in water bath. It is concluded that the homogenate extraction technology was an efficient method for extracting CPT and HCPT from C. acuminata leaves, with characteristics of less extraction time and high yield. Foundation project: This research was supported by National Key Technology R & D Program (grant no. 2006BAD18B04). Biography: SHI Wei-guo (1970–), male, Ph. D. candidate in Northeast Forestry University, Harbin 150040, P. R. China.)     

Effects of water stress on Haloxylon ammodendron seedlings in the desert region of Heihe inland river watershed, Gansu Province, China

The water relation and leaf gas exchange of saxoul (Haloxylon Ammodendron Bge, a C4 shrub) seedlings were studied under water stress in 2001. Saxoul seedlings maintained high transpiration when the soil moisture was above 11%. The seedlings were able to take up water from soil with above 6 % soil water content, which was the threshold level of soil moisture for seedlings. The relationship between transpiration and potential evaporation was linear for well-watered seedlings. The decrease of soil water availability led to different degrees of down-regulation of stomatal conductance, leaf transpiration and net CO2 assimilation rate. The stomata played a relatively small part in determining the net CO2 assimilation rate for the same seedling. The relationship between net CO2 assimilation rate and transpiration was linear diurnally, and reduction scale of leaf transpiration was much bigger than that of net CO2 assimilation rate by waters tress treatments, therefore intrinsic water-use-efficiency increased. High evaporative demand increased the leaf transpiration but inhibited net CO2 assimilation rate.Because of the effect of VPD on transpiration in this region, the transpiration of well-watered and mild water stress seedlings becomes responsive to change in stomatal conductance over a wider range.     

The contribution of root respiration of<Emphasis Type="Italic">Pinus koraiensis</Emphasis> seedlings to total soil respiration under elevated CO<Subscript>2</Subscript> concentrations

The impacts of elevated atmospheric CO₂ concentrations (500 μmol·mol⁻¹ and 700 μmol·mol⁻¹) on total soil respiration and the contribution of root respiration ofPinus koraiensis seedlings were investigated from May to October in 2003 at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Jilin Province, China. After four growing seasons in top-open chambers exposed to elevated CO₂, the total soil respiration and roots respiration ofPinus koraiensis seedlings were measured by a Li-6400-09 soil CO₂ flux chamber. Three PVC cylinders in each chamber were inserted about 30 cm into the soil instantaneously to terminate the supply of current photosynthates from the tree canopy to roots for separating the root respiration from total soil respiration. Soil respirations both inside and outside of the cylinders were measured on June 16, August 20 and October 8, respectively. The results indicated that: there was a marked diurnal change in air temperature and soil temperature at depth of 5 cm on June 16, the maximum of soil temperature at depth of 5 cm lagged behind that of air temperature, no differences in temperature between treatments were found (P>0.05). The total soil respiration and soil respiration with roots severed showed strong diurnal and seasonal patterns. There was marked difference in total soil respiration and soil respiration with roots severed between treatments (P<0.01); Mean total soil respiration and contribution of root under different treatments were 3.26, 4.78 and 1.47 μmol·m⁻²·s⁻¹, 11.5%, 43.1% and 27.9% on June 16, August 20 and October 8, respectively. Foundation item: This study was supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (KZCX1-SW-01) and the National Natural Science Foundation of China (30070158). Biography: LIU Ying (1976-), female, Ph. D. Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China. Responsible editor: Song Funan     

Photosynthesis and chlorophylla fluorescence of two poplars under water stress

In order to estimate drought tolerance in two species ofPopulus, Populus alba var. pyramidalis Bunge andPopulus nigra L. var. thevestina (Dode), widely planted at the southern margin of the Taklimakan Desert, responses of net photosynthesis and chlorophylla fluorescence to irradiance and water stress were examined under laboratory conditions. Results showed thatP. alba exhibited stronger drought tolerance thanP. nigra. A linear relationship between net photosynthetic rates (A _n) and electron transport rates (ETR) was found in both poplars under different irradiance and leaf water potentials. Net photosynthetic rates (A _n) in the two poplars significantly correlated linearly with the photochemical efficiency of the saturation light-adapted leaves throughout the range of leaf water potentials, suggesting that the leaf photochemical efficiency in saturation light-adapted leaves can be used to estimate leaf photosynthetic capacity and leaf water conditions in the two poplars within a magnitude of air temperature between 20 and 30°C. This research was supported by the Japan Society for the Promotion of Science (CAS-9601), the Chinese Academy of Sciences and partly supported by the National Natural Foundation of China (39870154).     

A study on the shade tolerance ofMuehlewbeckia complera

Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m⁻²·s⁻¹). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m⁻²·s⁻¹ to 569.00 μmol·m⁻²·s⁻¹ (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m⁻²·s⁻¹ or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m⁻²·s⁻¹ (8–961 lx), or 10 μmol·m⁻²·s⁻¹ for above 6 h. Foundation item: This study was supported by the Research Foundation of Northeast Forestry University. Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China. Responsible editor: Zhu Hong     

Research on the extension ofTamarix shrubs resulted from development projects in arid area

Tamarix plant is widely distributed in the arid areas of China for its great tolerance of draught, salt and alkali and attracts more attention by its strong capacity in windbreak and sand-fixations. “Tamarix dunes” constitute special desert bio-landscape in arid area. During last several decades,Tamarix shrubs declined and “Tamarix dunes” were also severely destroyed due to the land exploitation and serious deforestation, etc. From the 1980s until now, the extending phenomenon ofTamarix shrubs caused by developmental projects such as building highway, railway was studied in the western dry area of China, including western section of Hexi Corridor of Gansu, railroads and highways around the two greatest basin in Xinjiang and interior regions in Gurbantonggut desert, through on-the-spot survey along the transportation lines and setting up sampling plots along the roads. It was found that large quantities ofTamarix plants grow in the catchment area of low-lying lands that were formed by bulldozer operation during road building period. The extension ofTamarix shrubs caused by engineering was similar to that of the other section of the area to some extent, but went beyond the original distribution. This extension is beneficial to the ecological restoration and re-vegetation of western region of China and plays an important role in control of the sandstorms and improvement of ecological environments. As a result, it is necessary to make a further study on the extending phenomenon ofTamarix shrubs and to seek approach to promote wider extension ofTamarix shrubs in suitable habitats. Foundation Item: This study is supported by key projects of National Natural Science Foundation (39730100), National Foundation (30070640) and part of Project 973(G19990435). Biography: Huang Pei-You (1936-), Male, Professor in College of Life Science and Technology, Xinjiang University, Urumqi, 830046 Responsible editor: Chai Ruihai