Table of Content

18 June 2006, Volume 17 Issue 06

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Articles

Interrelations between plant communities and environmental factors of wetlands and surrounding lands in mid- and lower reaches of Tarim River

ZHAO Ruifeng^1,2; ZHOU Huarong¹; QIAN Yibing¹; ZHANG Jianjun³

2006, 17(06):  955-960 . 

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A total of 16 quadrants of wetlands and surrounding lands in the mid- and lower reaches of Tarim River were surveyed, and the data about the characteristics of plant communities and environmental factors were collected and counted. By using PCA (principal component analysis) ordination and regression procedure, the distribution patterns of plant communities and the relationships between the characteristics of plant community structure and environmental factors were analyzed. The results showed that the distribution of the plant communities was closely related to soil moisture, salt, and nutrient contents. The accumulative contribution rate of soil moisture and salt contents in the first principal component accounted for 3570%, and that of soil nutrient content in the second principal component reached 25.97%. There were 4 types of habitats for the plant community distribution, i.e., fenny-light salt-medium nutrient, moist-medium salt-medium nutrient, mesophytic-medium salt-low nutrient, and medium xerophyticheavy salt-low nutrient. Along these habitats, swamp vegetation, meadow vegetation, riparian sparse forest, halophytic desert, and salinized shrub were distributed. In the wetlands and surrounding lands of mid- and lower reaches of Tarim River, the ecological dominance of the plant communities was markedly and unitary-linearly correlated with the compound gradient of soil moisture and salt contents. The relationships between species diversity, ecological dominance, and compound gradient of soil moisture and salt contents were significantly accorded to binary-linear regression model.

Physiology and ecology of Pometia tomentosa photosynthesis in tropical seasonal rain forest

SONG Qinghai^1,3; ZHANG Yiping¹; ZHENG Zheng¹; YU Guirui²; SUN Xiaomin²

2006, 17(06):  961-966 . 

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Pometia tomentosa is a dominant uppermost canopy tree in Xishuangbanna tropical seasonal rain forest. In this paper, the photosynthetic characteristics of the three layers of P. tomentosa canopy were measured with Li-6400 portable photosynthesis system, and the results showed that P. tomentosa had the characteristics of high light saturation point (1 000~1 500 μmol·m^-2·s^-1) and low compensation point (7.7~15.3 μmol·m^-2·s^-1). Its leaf photosynthesis had the adaptive responses when the high irradiance changed. PAR was the main factor affecting the diurnal changes of net photosynthesis. In December, the leaf grew well, and had a high ability of photosynthesis, with the diurnal change of P_n for upper layer exhibiting single-peaked pattern and the maximum value being 8.9 μmol CO₂·m^-2·s^-1. April was the alternative period of old and young leaves, and the ability of photosynthesis was dropped, with the diurnal change of P_n for upper layer following double-peaked curve and the maximum value being 4.3 μmol CO₂·m^-2·s^-1. The highest net photosynthesis rate was observed in July, with the diurnal change of P_n for upper and middle layers exhibiting single-peaked pattern and that for lower layers being double-peaked. Short-term enriched CO₂ concentration could evidently increase the photosynthesis of P.tomentosa, while the stomatic conductance and transpiration would be inhibited. When the CO₂ concentration increased from 400 μmol·mol^-1 to 800 μmol·mol^-1, water use efficiency (WUE) was increased by 50%～100% in dry season, but rather low in wet season.

Soil moisture characteristics at the boundary of forestland-grassland in hilly area of Loess Plateau

YOU Wenzhong^1,2,3; ZENG Dehui¹; LIU Mingguo²; SONG Xide⁴

2006, 17(06):  967-971 . 

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In this paper, the spatial distribution pattern of soil moisture at the boundary of forestland-grassland in hilly area of Loess Plateau was studied in dry season of June and rainy season of August 2004. The results showed that the variance coefficient of soil moisture content was smaller, and the difference of moisture content between soil layers was less significant in forestland than in grassland in June while reversed in August. There was a weak or medium differentiation of moisture content in different soil layers at the boundary of forestland-grassland. The edge effect area at the boundary was from 2 m (0.4 of tree height) outside forestland to 2 m inside forestland in June, and from 2 m outside forestland to 4 m (0.8 of tree height) inside forestland in August. The forestland-grassland landscape could be divided into 3 parts, i.e., grassland area, forest edge area, and forestland area, and the vertical distribution of soil moisture in these three parts showed different traits. In June, soil moisture content increased with increasing soil depth, with a smaller increment in grassland than in forestland, but in August, it was reversed. The vertical distribution of soil moisture at forest edge area showed an in-between feature.

Physiological-ecological effects of Populus davidiana-Quercus liaotungensis mixed forest in Ziwuling forest area

QIN Juan^1,2; SHANGGUAN Zhouping^1，2

2006, 17(06):  972-976 . 

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This paper studied the soil physical-properties under Populus davidiana, Quercus liaotungensis, and Populus davidiana-Quercus liaotungensis mixed forest in the Ziwuling forest area of Loess Plateau, and the leaf photosysthetic characteristics of these three types of forests. The results showed that soil moisture content in 0~300 cm layer was the highest under P. davidiana forest, and obviously increased below 200 cm in depth under P.davidiana-Q. liaotungensis mixed forest, which was 10.5%~19.76% higher than that under Q. liaotungensis forest. In 0~60 cm layer, P. davidiana forest showed the highest soil bulk density and the lowest soil porosity, while P.davidiana-Q. liaotungensis mixed forest presented the lowest soil bulk density and the highest soil porosity, and both of these indices surpassed their corresponding values under pure forests, which indicated that the mixed forest could make effective use of water in deep soil, and obviously improved soil physical and chemical properties. P. davidiana and Q.liaotungensis had a higher content of leaf chlorophyll than P. davidiana-Q.liaotungensis mixed forest, and Q. liaotungensis presented the highest leaf chlorophyll content. Q. liaotungensis had the highest photosynthetic rate and stomatal conductance, followed by P. davidiana, and by P. davidiana-Q.liaotungensis mixed forest. The water use efficiency of the forests ranked in the decreasing order of Q. liaotungensis in pure forest, Q. liaotungensis in mixed forest, P. davidiana in mixed forest, and P. davidiana in pure forest. Q. liaotungensis in mixed forest presented the highest F_v/F_m and F_v/F_o, and did not remarkably differ from those in pure forest, but in the mixed forest, the F_v/F_m and F_v/F_o P. davidiana were markedly lower than those of P. davidiana in pure forest. Both the q_p and NPQ of P. davidiana and Q. liaotungensis in pure forests were higher than those in mixed forest, respectively. In Ziwuling forest area, Q. liaotungensis in Q. liaotungensis-dominant climax community tended to be more stable, and grew better than Q. liaotungensis in P.davidiana-Q. liaotungensis mixed forest, and P. davidiana would be gradually replaced. Compared with P. davidiana in pure forest, P. davidiana in its mixed forest was at a disadvantage in its growth.

Fog water absorption by the leaves of epiphytes and non-epiphytes in Xishuangbanna

ZHENG Yulong¹; FENG Yulong^1,2

2006, 17(06):  977-981 . 

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Xishuangbanna is located at the northern margin of tropics. Its climate is different from that of typical tropics, but the rainforest there is not very different from that of the typical tropics in Southeast Asia. The main problems in Xishuangbanna are seasonal drought and low temperature. Fog may contribute to the development of rainforest here, but related studies are few. This study is aimed to know whether the leaves of epiphytes and non-epiphytes in Xishuangbanna can directly absorb fog water and contribute to their water status recovery, and whether epiphytes are more competent than non-epiphytes in their leaf fog water absorption. The study was conducted in dry season, and four species of epiphytes and six species of non-epiphytes were investigated. The effect of fog was imitated by spraying leaves with distilled water. For epiphytes and non-epiphytes, their leaf water potential (Φ), relative water content (RWC), and amount of absorbed water increased gradually with the time of spraying, but the Φ of epiphytes increased more quickly than that of non-epiphytes. The leaves of epiphytes Bolbitis scandens and Rhaphidophora decursiva could absorb fog water more quickly, and increase their RWC more greatly than those of non-epiphytes, indicating that these epiphytes were more competent than non-epiphytes in their leaf fog water absorption. The fog water absorption capacity of the leaves in epiphytic orchid Coelogyne occultata and Staurochilus dawsonianus was lower than that in Amischotolype hispida and Mananthus patentiflora, but higher than that in other four non-epiphytes. The Φ of epiphytes at early evening when no fog was formed was significantly lower than that at early morning, suggesting that fog water was absorbed by epiphytes at night to improve their leaf water status. Non-epiphytes did not need to absorb fog water directly through leaves, and they could recover their leaf water status through absorbing soil water by root system. Epiphytes except C. occultata had a much more leaf biomass than non-epiphytes, which was also beneficial to their leaf fog water absorption. Because there was abundant fog in dry season in Xishuangbanna, the Φ of test ten species was higher than -0.8 MPa, indicating that water stress was not serious in dry season.

Seed population dynamics and germination characteristics of Eupatorium adenophorum

WANG Wenqi; WANG Jinjun; ZHAO Zhimo

2006, 17(06):  982-986 . 

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With bare land, farmland, and masson pine forestland in the Eupatorium adenophorum invaded area of Dechang County, Sichuan Province as test habitats, this paper studied the seed population dynamics of E. adenophorum at the levels of seed rain and seed bank, and its seed germination characteristics under effects of light and soil medium. The results showed that in the three habitats, the seed population of E. adenophorum only existed from March to June, and reached its peak by the end of April. The annual seed rainfall in bare land habitat amounted to 2.4×10⁵ individuals per square meter, and all the seeds were distributed in the soil layer above 2 cm. The thousand seed weight and seed activity of E. adenophorum in bare land habitat were significantly higher than those in another two habitats. No active seed was found in the three habitats by the first ten days of July. Under artificial light condition, full light had some inhibitory effects on seed germination, while 28% of full light gave the highest germination rate. Sandy loam soil was more favorable for the seed germination, while in unreclaimed red soil, both the germination velocity and germination rate were the lowest.

Competitive mechanism of non-predator-prey metapopulation system based on competition and dispersal ability

LIANG Renjun^1,2; LIN Zhenshan¹

2006, 17(06):  987-991 . 

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Species competition is one of the important ecological courses that influence the evolvement of ecosystem. To an ecosystem of predator-prey, competition is always bidirectional, that is there is competitive infection on superior species and inferior species. Without regarding to the destruction of habitat, the bidirectional competitive mechanism was introduced, Tilman’ unilateral competitive model was extended to bidirectional competitive model of metapopulation. At the same time, the competitive dynamics of the 6-metapopulation species are simulated on computer. The results showed that at the equilibrium, the coexistence condition of population competition is migratory ability and competition ability take on exponential negative correlation, the outcome of competition makes the superior and inferior sequence changed, the exclusion and coexistence of species competition was affected by migratory ability and competition ability, the metapopulations which are excluded in local patches can exist in regional scale, that is escaping coexistence.

Effects of forest and swamp on hydrochemical characteristics of streams

MAN Xiuling; FAN Jinfeng; TAN Xiaojing; CAI Tijiu

2006, 17(06):  992-996 . 

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With the upper reaches of Gongbiela River in the northeast part of Xiaoxing’an Mountains as test area, this paper studied the hydrochemical characteristics of the streams in forest and swamp during the period of June～September 2004. The results indicated that the hydrochemistry of forest and swamp streams belonged to calcium-bicarbonate type Ⅰ (C^Ca₁). The pH value, mineralization rate, total hardness, and HCO₃^-, SO₄^2-, Ca²⁺, Mg²⁺ and Fe concentrations of forest streams were lower than those of swamp streams, while the concentrations of total N, total P, Cl^-, K⁺, and Na⁺ were in adverse. In both of the streams, the contents of heavy metal elements such as Fe, Mn, Cu, Zn, Cd, Hg and Pb were lower than the classⅠin Environmental Quality Standards for Surface Water (EQSSW) of China. The concentrations of total N and P in forest streams were （0.27±0.04） mg·L^-1 and （0.040±0.005） mg·L^-1, respectively, being significantly higher than those (（0.21±0.02） mg·L^-1 and （0.025±0.004） mg·L^-1) in swamp streams. Swamp wetland had a stronger ability in depositing and adsorbing N and P, with more NH₄⁺-N adsorbed than NO₃^--N, and also had a stronger ability on the reduction and release of Fe, with the Fe content (（0.26±0.05） mg·L^-1) in its streams obviously higher than that in forest streams.

Hyperspectral remote sensing estimation models on vegetation coverage of natural grassland

LIU Zhanyu¹; HUANG Jingfeng¹; WU Xinhong²; DONG Yongping²; WANG Fumin¹; LIU Pengtao³

2006, 17(06):  997-1002 . 

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By using ASD FieldSpec Pro FR^TM spectroradiometer, the spectral measurement of natural grassland in Xilingole Leaguer of Inner Mongolia was performed, with the vegetation coverage of natural grassland calculated, and the correlation of 25 hyperspectral feature variables with the vegetation coverage of natural grassland was analyzed. The results showed that there were 17 variables correlated significantly with the vegetation coverage of natural grassland, among which, the correlation coefficient between vegetation coverage and the area of red edge peak calculated as the sum of the amplitudes between 680 nm and 780 nm (∑dr 680～780 nm) was the highest, with the value of 0.781. The basic experimental data including the vegetation coverage and canopy reflectance of natural grassland were classified into two groups. One group was used as the training sample to build the regression models with onesample linear method, nonlinear method, and stepwise analysis method, while the other was used as the testing sample to test the precision of regression models. It was suggested that the variable of the area of red edge peak calculated as the sum of amplitudes between 680 nm and 780 nm (∑dr 680～780 nm) was the best one to univariate general linear model, with a standard deviation of 10.4% and an estimation precision of 83.99%, while the stepwise regression technique was not effective to estimate the grassland coverage with raw hyperspectral canopy reflectance.

Distribution of organic carbon pools in different sizes of soil aggregates in Loess Plateau

LIU Yi^1，2;LI Shiqing^1，2;SHAO Ming’an¹;ZHANG Yuexia²

2006, 17(06):  1003-1008 . 

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According to the types of vegetation and soil, 22 soil profile samples (0～20 cm, 20～40 cm and 40～60 cm) were collected from different regions of Loess Plateau to approach the distribution of organic carbon pools in different sizes of soil aggregates. The results showed that the organic carbon content and storage in all sizes of soil aggregates were decreased with increasing soil depth. For each soil layer, the organic carbon content had an increasing trend in the aggregates with the sizes from ＞5 mm, 2～5 mm, 1～2 mm to 0.25～1 mm, and a descreasing trend from 0.25～1 mm to ＜0.25 mm. Because of the different proportions of each size of soil aggregates, the organic carbon storage and content in different sizes of soil aggregates were not the same, i.e., the storage was decreased with the sizes from ＞5 mm, 2～5 mm to 1～2 mm, while increased from 1～2 mm, 0.25～1 mm to ＜0.25 mm. Except Eum-Orthic Anthrosols had the highest organic carbon content in its aggregate of ＜0.25, Ust-Sandiic Entisols, Los-Orthic Entisols and Hap-Ustic Isohumisols had a peak value in their aggregate of 0.25～1 mm. The organic carbon storage was the highest in the aggregate of ＜0.25 mm in UstSandiic Entisols and Los-Orthic Entisols, and in the aggregate of ＞5 mm in Hap-Ustic Isohumisols and Eum-Orthic Anthrosols. The soil organic carbon content and storage under different types of vegetation had the trend of natural forestland ＞bare land＞ artificial forest land＞farming land.

Spatial analysis on land use in Xishuangbanna

SONG Guobao^1,2; LI Zhenghai^1,3; GAO Jixi³; WANG Haimei⁴

2006, 17(06):  1009-1013 . 

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Based on remote image and GIS technology, this paper analyzed the relationships between land use system and natural topographic factors such as elevation, slope, and river system in Xishuangbanna. The results showed that the land use system in the study region was dominated by forestland, cropland and grassland. The area of forestland was 13 420 km², accounting for 74% of the total, and that of cropland and grassland was 3 251 km² and 2 332 km², accounting for 13% and 18% of the total, respectively. The areas of these three land use types varied with elevation in singlepeaked curve. Forestland mainly distributed around the elevation of 1 000~1 200 m, while cropland and grassland centralized at the elevation of 900 m. Urban land and cropland, which were greatly influenced by human activity, had lower slope index than forestland and grassland. Besides elevation and slope, river system in valley had effects on land use condition. With increasing buffer distance in valley, a strong spatial pattern of land use type was presented, i.e., cropland, urban land and unused land concentrated greatly adjacent to water, while forestland and grassland were far away from valley. A landscape with relatively primary status, which was comprised of forestland as matrix, river as corridor, and cropland as patch, would come into being.

Soil organic carbon storage and its spatial distribution characteristics in Hainan Island: a study based on HNSOTER

LU Chengwen^{1, 2}; CUI Shuqing¹; ZHAO Lai¹

2006, 17(06):  1014-1018 . 

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The study based on HNSOTER and supported by GIS showed that in Hainan Island, the total amount of soil organic carbon in the standard profile depth of 0~100 cm was about 2.78×10⁸ t, and the soil organic carbon density in 0~20 cm and 0~100 cm profile depth was 0.3~18.8 kg·m^-2 and 1.0~32.1 kg·m^-2, with an area-weighted means of 3.3 kg·m^-2 and 8.4 kg·m^-2, respectively. Soil organic carbon density varied significantly with different landform, lithology and soil, which tended to decrease from the mountains in the middle part of Hainan Island to its coastal plain, and had some differences between 0~20 cm and 0~100 cm profile depth. The areas of high soil organic carbon density in 0~20 cm profile depth were mainly distributed in the mountains and northern basalt tableland, while those in 0~100 cm profile depth were in the middleeastern mountains and tableland. The distribution center of soil organic carbon density in 0~100 cm profile depth had a significant shift to the eastern part, compared with that in 0~20 cm profile depth.

Calculation of soil water erosion modulus based on RUSLE and its assessment under support of artificial neural network

LI Yuhuan^1,2,3,4; WANG Jing¹;ZHANG Jixian²

2006, 17(06):  1019-1026 . 

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With Hengshan County of Shanxi Province in the North Loess Plateau as an example, and by using ETM+ and remote sensing data and RUSLE module, this paper quantitatively derived the soil and water loss in loess hilly region based on “3S" technology, and assessed the derivation results under the support of artificial neural network. The results showed that the annual average erosion modulus of Hengshan County was 103.23 t·hm^-2, and the gross erosion loss per year was 4.38×10⁷t. The erosion was increased from northwest to southeast, and varied significantly with topographic position. A slight erosion or no erosion happened in walled basin, flatheaded mountain ridges and sandy area, which always suffered from dropping erosion, while strip erosion often happened on the upslope of mountain ridge and mountaintop flat. Moderate rill erosion always occurred on the middle and down slope of mountain ridge and mountaintop flat, and weighty rushing erosion occurred on the steep ravine and brink. The RUSLE model and artificial neural network technique were feasible and could be propagandized for drainage areas' control and preserved practice.

Nitrogen flow in Huizhou region

MA Xiaobo¹; WANG Zhaoyin^1,2; Albert KOENIG³; DENG Jiaquan⁴

2006, 17(06):  1027-1033 . 

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Eutrophication is a serious problem of water body pollution. By the method of material flow accounting, this paper studied the human activities-related nitrogen flow in the system of environment and anthroposphere in Huizhou region. The non-point source pollution was quantified by export coefficient method, and the domestic discharge was estimated by demand-supply method. The statistic and dynamic analyses based on the investigation data of 1998 showed that the major nitrogen flows in this region were river loads, fertilizer and feedstuff imports, atmospheric deposition, animal excretes’ degradation and volatilization, and the processes relating to burning and other emissions. In 1998, about 40% of nitrogen was detained in the system, which could be accumulated and yield potential environmental problems. The nitrogen export in this region was mainly by rivers, accounted for about 57%. A comparison of Huizhou region with the Danube and Changjiang basins showed that the unit area nitrogen exports in these three regions were of the same magnitude, and the per capita nitrogen exports were comparable.

Ecological environmental quality assessment of Hangzhou urban area based on RS and GIS

XU Pengwei; ZHAO Duo

2006, 17(06):  1034-1038 . 

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In allusion to the shortage of traditional ecological environmental quality assessment, this paper studied the spatial distribution of assessing factors at a mid-small scale, and the conversion of integer character to girding assessing cells．The main assessing factors including natural environmental condition, environmental quality, natural landscape and urbanization pressure, which were classified into four types with about eleven assessing factors, were selected from RS images and GIS-spatial analyzing environmental quality vector graph. Based on GIS, a comprehensive assessment model for the ecological environmental quality in Hangzhou urban area was established. In comparison with observed urban heat island effects, the assessment results were in good agreement with the ecological environmental quality in the urban area of Hangzhou.

Effects of soil surface mulching on the growth and physiological characteristics of grafted and non-grafted cucumbers in solar greenhouse

ZHAI Sheng^{1, 2}; LIANG Yinli¹; WANG Juyuan³; DAI Quanhou⁵; DU Sheni^{1, 4}; YOU Haixia⁴; CHEN Jiarui⁴

2006, 17(06):  1039-1044 . 

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This paper studied the effects of wheat straw mulching, plastic film mulching, and wheat straw plus plastic film mulching on the growth and physiological characteristics of grafted and non-grafted Cucumis sativus in solar greenhouse. The results showed that compared with the control, the plant height, stem diameter, photosynthetic rate, and root vitality of grafted C.sativus under wheat straw plus plastic film mulching, plastic film mulching, and wheat straw mulching were increased by 91, 71 and 57 cm, 0.127, 0.086 and 0.111 cm, 2.63, 2.08 and 1.36 μmol·m^-2·s^-1, and 0.98, 0.48 and 0.8 mg TTC·g^-1 FW, respectively, while non-grafted C. sativus had a less increment. The chlorophyll content of grafted C. sativus under wheat straw plus plastic film mulching and wheat straw mulching was 1.8% and 3.15% higher than the control, respectively, but that under plastic film mulching was 3.8% less than the control. Soil surface mulching increased the dry weight per plant, early yield, and total yield. Under wheat straw plus plastic film mulching, plastic film mulching, and wheat straw mulching, the individual yield of grafted C. sativus was 16%, 5.3% and 3.4% higher than that of non-grafted C. sativus, respectively.

Antioxidant enzyme activities and proline content in maize seedling and their relationships to cold endurance

GAO Canhong; HU Jin; ZHENG Yunye; ZHANG Sheng

2006, 17(06):  1045-1050 . 

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This paper studied the catalase (CAT) and peroxidase (POD) activities and proline (Pro) content in the seedling’s root, mesocotyl (including coleoptile node), and coleoptile (including infancy leaf) of two maize inbred lines Huang C (cold-endurance) and Mo17 (cold-sensitive), and their relationships to cold endurance under low temperature stress (5 ℃, 3 d). The results showed that under the low temperature stress, Huang C had a significantly higher relative growth rate of mesocotyl and coleoptile than Mo17, and the change rates of CAT and POD activities and Pro content in the root, mesocotyl and coleoptile of Huang C were higher than those of Mo17. The plasma membrane permeability of the three segments of both inbred lines was significantly increased, but Huang C had significantly lower plasma membrane permeability than Mo17. Compared with those under normal temperature, the seedlings under low temperature stress had higher CAT activity and Pro content, and the increment was higher in Huang C than in Mo17. The POD activity in the three segments of the seedlings under low temperature stress was reduced, and the decrement was lower in Huang C than in Mo17. Stepwise regression analysis showed that under low temperature stress, the dry matter accumulation in cold-endurance line Huang C was mainly related to Pro content, while that in cold-sensitive line Mo17 was mainly related to POD activity. Mesocotyl was the most responsive tissue to low temperature. The change rate of Pro content in mesocotyl was more closely correlated with the cold endurance of maize inbred lines than the other physiological parameters.

Physiological and biochemical indexes of drought resistance of sugarcane (Saccharum spp.)

GAO Sanji; LUO Jun; ZHANG Hua; CHEN Rukai; LIN Yanquan

2006, 17(06):  1051-1054 . 

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Through factor analysis and grey correlative degree analysis, this paper studied the relationships of sugarcane leaf relative water content (RWC), membrane lipid peroxidation metabolism, active oxygen metabolism, photosynthesis, and stalk yield with drought resistance of sugarcane. The results suggested that under drought stress, the plasma membrane permeability (PMP) and malondialdehyde (MDA) content were markedly increased, while RWC, superoxide dismutase (SOD) activity, chlorophyll (Chl) content, PSⅡ photochemical efficiency (F_v/F_m), PSⅡ potential activity (F_v/F_o), variable fluorescence quenching rate (ΔF_v/F_o), efficiency of potential quantum conversion (ΔF_v/F_t), and single stalk weight (SSW) were remarkably decreased. The correlation of SSW with test indexes was decreased in the order of PMP, SOD activity, MDA content, RWC, F_v/F_o, F_v/F_m, Chl content, ΔF_v/F_o and ΔF_v/F_t. Through factor analysis, the test indexes were divided into four common factors, among which, the indexes of photosynthesis played important roles in the first factor, RWC and the indexes of active oxygen metabolism dominated in the second factor, while SSW and Chl content played primary roles in the third and fourth factor, respectively. The grey correlative degree of SSW with other indexes was in the rank of F_v/F_m, PMP, F_v/F_o, RWC, MDA content, SOD activity, ΔF_v/F_t, Chl content, and ΔF_v/F_o.

Soil biological activities at maize seedling stage under application of slow/controlled release nitrogen fertilizers

WU Zhijie¹;CHEN Lijun¹;LIANG Chenghua²;ZHANG Lili¹;WANG Weicheng²;YANG Defu³

2006, 17(06):  1055-1059 . 

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With pot experiment and simulating field ecological environment, this paper studied the effects of different slow/controlled release N fertilizers on the soil nitrate-reductase and urease activities and microbial biomass C and N at maize seedling stage. The results showed that granular urea amended with dicyandiamide (DCD) and N-(n-bultyl) thiophosphoric triamide (NBPT) induced the highest soil nitratereductase activity, granular urea brought about the highest soil urease activity and microbial biomass C and N, while starch acetate (SA)-coated granular urea, SAcoated granular urea amended with DCD, methyl methacrylate (MMA)-coated granular urea amended with DCD, and no N fertilization gave a higher soil urease activity. Soil microbial C and N had a similar variation trend after applying various kinds of test slow/controlled release N fertilizers, and were the lowest after applying SAcoated granular urea amended with DCD and NBPT. Coated granular urea amended with inhibitors had a stronger effect on soil biological activities than coated granular urea, and MMA-coating had a better effect than SA-coating.

Effects of allelopathic rice on rhizosphere microbial flora and enzyme activity

HU Kaihui; LUO Qingguo; WANG Shihua; LIN Xuan; LIN Wenxiong

2006, 17(06):  1060-1064 . 

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This paper studied the dynamics of microbial flora and enzyme activity in the rhizosphere of allelopathic rice PI312777 (PI) and nonallelopathic rice Lemont (LE) at the growth stage of 3～7 leaves. The results showed that in the rhizosphere of PI, the amounts of bacteria, actinomycetes and azotobacter were 11.2%～28.3%，40%～78.6% and 111.5%～173.9%, respectively, while that of fungi was lower, with the maximum being 25.5% of that in the rhizosphere of LE, suggesting that allelopathic rice PI promoted the growth of bacteria, actinomycetes and azotobacter, but inhibited that of fungi. Further analysis on the physiological groups of microbial flora showed that PI favored the growth of ammonifier, aerobic azotobacter, aerobic cellulose- decomposer, sulphate- reducer, nitrite- bacteria and nitrate- bacteria, among which, ammonifier and aerobic azotobacter increased by 53.7% and 57.6%, respectively, while inhibited the growth of desulphate bacteria and denitrifyier. Moreover, PI increased the activities of urease, phosphatase and sucrase, but decreased the catalase activity in its rhizosphere.

Feeding preference of Plutella xylostella (Lepidoptera: Plutellidae) larva to its hosts

LI Hongshan^{1, 2};WANG Juan¹;Wei Hui³;DAI Huaguo¹;Wang Junhua¹

2006, 17(06):  1065-1069 . 

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The feeding experiment with different sorts of Brassica vegetable crops showed that Plutella xylostella larva preferred the seedlings of Chinese cabbage (Brassica campestris L.), radish (Raphanus sativus L.) and caixin (Brassica campestris L.) to those of rape (Brassica napus L.) and cabbage (Brassica olereacea L.), with a selection proportion of 93.33% and 6.67% between Chinese cabbage and rape, and of 16.67% and 83.33% between cabbage and caixin. On the whole, the feeding preference of P. xylostella larva was less related to the contents of soluble glucide and starch in the vegetables, but had a definite negative correlation to the content ratio of these compounds. The P. xylostella larva fed with Chinese cabbage and caixin grew better than that fed with rape and cabbage, and the feeding amount and body weight of per larva were 0.583～0.637 cm² and 2.07～2.18 mg, respectively. The larva preferred damaged vegetable seedlings, too.

Electroantennogram and behavioral responses of Monochamus alternatus to the volatiles from Pinus thunbergii with different physiological status

HAO Dejun¹;MA Fenglin²;WANG Yan²;ZHANG Yonghui¹;DAI Huaguo¹

2006, 17(06):  1070-1074 . 

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The volatiles from healthy and pinewood nematode-infested branches of Pinus thunbergii were collected by distillation, and analyzed by using HPLC and GC-MS. Electroantennogram (EAG) and behavioral responses of Monochamus alternatus with different physiological status to the volatiles were investigated respectively.The results showed that unmated beetle had a greater EAG response potential to the volatiles from healthy branch than to those from infested branch, while it was reverse for mated beetle. The EAG response of unmated beetle under 15 days-old to the volatiles from healthy branch increased with its age. “Y” tube olfactory test showed unmated beetle had positive response to the volatiles from healthy branch and negative response to those from infested branch, while mated beetle showed positive response to the volatiles from infested branch and negative response to those from healthy branch. Female beetle with its age from 1 day to 15 days-old and male beetle from 1 day to 9 days-old had an increasing positive response to the volatiles from healthy branch, but the male after 9 days-old showed a negative response. It could be concluded that M. alternatus with different physiological status all had special sensitivity and selectivity to host tree.

Structural characteristics of arthropod community in grapery

ZOU Yunding¹;LI Changgen^1,2;BI Shoudong¹;WU Houzhang¹;CHEN Xiangyang¹;LI Fen¹;ZHOU Xiazhi¹;LIN Xuefei¹

2006, 17(06):  1075-1080 . 

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By the method of principal component analysis, this paper analyzed the characteristic parameters of arthropod community and its phytophagous and predacious sub-communities in grapery. The results showed that in the first principal component, the contribution of arthropod community, phytophagous sub-community and predacious sub-community was 66.70%, 73.39% and 54.17%, respectively. For arthropod community, the absolute values of normalized regressive coefficients of individuals’ number N, Hill diversity index N₁, Hill diversity index N₂ and McIntosh index D_mc were larger, indicating their greater contribution on the community. For phytophagous sub-community, N, N₁, N₂, N and S (total species) had greater contribution; while for predacious sub-community, the greater contribution was made by N₁, N₂, Shannon-Wiener diversity index H'and abundance R. Synthetically, N₂ and N₁ had greater contribution on the arthropod community and its phytophagous and predacious sub-communities in grapery, comparing with other characteristic parameters.

Pb-tolerance of ectomycorrhizal fungi from polluted and unpolluted sites under different P levels

LIANG Zhenchun; HUANG Yi; AO Xiaolan

2006, 17(06):  1081-1085 . 

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By the method of liquid culture, this paper studied the effects of different P and Pb doses on the biomass production of three strains of ectomycorrhizal fungi, and the P and Pb concentrations in their mycelium. The results showed that under the application of P and Pb, the biomass production of strains ZC₁ and ZC₂ collected from mining area was significantly higher than that of strain GV collected from non-polluted site. At low P level (0.16 mmol·L^-1), the growth of these three ectomycorrhizal fungi was inhibited by the increasing dose of Pb; while at higher P levels (0.81and 2.42 mmol·L^-1), increasing dose of Pb inhibited the growth of GV significantly, but had little effects on ZC₁ and ZC₂. In all treatments, the Pb concentration in GV mycelia was significantly higher than that in the mycelia of ZC₁ and ZC₂. Under the same dose of Pb, the P concentration in GV mycelia was higher at low P level, but lower at higher P levels than that in ZC₁ and ZC₂ mycelia. The increase of Pb dose decreased the P concentration in ZC₁ and ZC₂ mycelia, but had little effect on that in GV mycelia. In comparing with GV, ZC₁ and ZC₂ had the characteristics of fast growth and low Pb and high P accumulation in their mycelia, indicating that the strains of ecomycorrhizal fungi collected from polluted area had a higher tolerance to environmental stress.

Hydrolysis characteristics of enrofloxacin

WU Yinbao¹; LIAO Xindi¹; WANG Zhisan¹; CHEN Zhangliu²; ZHOU Yang¹

2006, 17(06):  1086-1090 . 

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By the method of high-performance liquid chromatography (HPLC), this paper studied the hydrolysis characteristics of enrofloxacin under conditions of different pH, light, and microorganism to assess its ecological risk. The results showed that no ciprofloxacin was found in the hydrolyzed products of enrofloxacin. Under the conditions of 50 ℃ and pH 1～10, the hydrolyzation rate of enrofloxacin was less than 10% within 5 days. The halflife of enrofloxacin was longer than one year at normal temperature and in dark, and buffer’s pH had no significant effects on the hydrolysis of enrofloxacin. The degradation of enrofloxacin in natural water was strongly affected by light. Under outdoor natural light condition, enrofloxacin degraded quickly and was not examined after 3 days; while under indoor natural light condition, it degraded slowly, with the degradation rate being 48%, 72% and 65% after 31 days when its initial concentration in water was 0.05, 0.2 and 1.0 mg·L^-1, respectively. Enrofloxacin was very steady in dark, and microorganisms had no significant effects on its degradation. Owing its rapid degradation under outdoor natural light condition, enrofloxacin might have no direct harmfulness to aquatic ecosystem, but its potential ecological risk should not be neglected once entering into aquatic ecosystem, especially in bottom mud.

Photochemical degradation of chlorothalonil in aqueous solution

LI Xuede¹;HUA Rimao¹;YUE Yongde²;LI Ying³;TANG Feng¹;TANG Jun¹

2006, 17(06):  1091-1094 . 

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The study on the effects of light source, solution pH and temperature, and surfactant on the photochemical degradation of chlorothalonil showed that the halflife of chlorothalonil photodegradation under high pressure mercury lamp (HPML), UV lamp and sunlight was 22.4, 82.5 and 123.8 min, respectively. Under HPML and sunlight, chlorothalonil had a higher photolysis rate in alkaline solution than in neutral and acid solution. The photolysis rate increased with increasing solution temperature in the range of 10 ℃~40 ℃, which was doubled when the temperature increased every 10 ℃. Sodium laurylsulfonate (SDS), sodium dodecylbenzene sulfonate (SDBS), Tween 60 and Span 20 showed significant photosensitizing effects, while cetyltrimethylammonium bromide (CTAB) had significant photoquench effect on the photolysis of chlorothalonil.

Responses of different Vicia faba varieties’ photosynthetic characteristics to Pb pollution

LEI Dongmei; DUAN Changqun; HE Feng; SONG Chunjing

2006, 17(06):  1095-1098 . 

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In a field experiment of simulated Pb pollution (40 and 250 mg·kg^-1), this paper investigated the net photosynthetic rate, stomal conductance, transpiration rate, intercellular CO₂ concentration, water use efficiency, and chlorophyll content of three Vicia faba varieties K0883，K0502 and K0697. The results showed that under Pb pollution, there was no significant variation in the transpiration rate and stomal conductance of the three varieties, but their chlorophyll content increased in different extents. When the Pb concentration was 250 mg·kg^-1, the net photosynthetic rate and water use efficiency of K0883 were increased by 121.80% and 193.70%, respectively, while its intercellular CO₂ concentration was decreased by 42.76%. According to the Perturbation test based on the responses of test photosynthetic characteristics, the Pbresistance of the three varieties was in the sequence of K0883＞K0697＞K0502. It was concluded that the responses of different photosynthetic indexes and different Vicia faba varieties to small dosage Pb pollution were differed, and the intraspecific difference could only be detected by the integration of all photosynthetic indices.

Atmospheric nitrogen wet deposition and its effects on wetland water environment of Shanghai area

ZHANG Xiufeng

2006, 17(06):  1099-1102 . 

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Based on the observation data of the rainfall and its NO₃^--N and NH₄⁺-N concentrations in Shanghai area from 1998 to 2003, and by the method of single factor evaluation, this paper studied the flux of atmospheric nitrogen wet deposition and its effects on wetland water environment of this area. The results showed that in the six years, the nitrogen content in the rainwater was rather high, with an average concentration of NO₃^--N and NH₄⁺-N being 2.59 mg·L^-1 and 2.16 mg·L^-1, respectively, and a total inorganic nitrogen of 4.74 mg·L^-1, which exceeded the water eutrophication level (0.2 mg·L^-1). According to the nitrogen concentration, the rainwater belonged to V and inferior V types of surface water quality. The nitrogen flux by wet deposition in the six years was 58.1 kg·hm^-2·yr^-1, among which, NO₃^--N accounted for 54%. The effects of atmospheric nitrogen wet deposition on the eutrophication of the wetland water environment should be paid more attention.

Tolerance of Craspedacusta sowerbyi xinyangensis to the stresses of some ecological factors

WANG Danli¹;XU Shanliang¹;JIANG Honglei²;YANG Hua¹

2006, 17(06):  1103-1106 . 

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This paper studied the tolerance of Craspedacusta sowerbyi xinyangensis to the stresses of temperature, salinity, and pH from the aspects of its living status, morphology and survival, and measured its oxygen consumption rate and oxygen tolerance at different temperatures. The results indicated that the suitable temperature and pH of C. sowerbyi xinyangensis were 15 ℃～25 ℃ and 6.0～8.2, respectively. C. sowerbyi xinyangensi had a low tolerance to salinity, and it could only survive for 96 h when the salinity was 2. C. sowerbyi xinyangensi could bear low DO, and its lethal DO was 0.26 mg·L^-1 at 20 ℃. The average oxygen consumption amount and rate of C. sowerbyi xinyangensi increased with increasing temperature.

Mass-balance ecopath model of Beibu Gulf ecosystem

CHEN Zuozhi^1,2,3; QIU Yongsong²; JIA Xiaoping²

2006, 17(06):  1107-1111 . 

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Based on the investigation of fishery resources and eco-environment in the Beibu Gulf of northern South China Sea from October 1997 to May 1999, and with EwE software, a mass-balance ecopath model of Beibu Gulf ecosystem was constructed, which consisted of 16 functional groups (boxes) including marine mammals and seabirds, each representing the organisms with similar roles in the food web, and covered the main trophic flow in Beibu Gulf ecosystem. The food web in Beibu Gulf ecosystem was dominated by detrital path, and benthic invertebrate played a significant role in transferring energy from detritus to higher trophic levels. Phytoplankton was the primary producer, and the fractional trophic levels ranged from 1.00 to 4.04, with marine mammals occupying the highest trophic level. By using network analysis, the system network was mapped into a linear food chain, and six discrete trophic levels were found, with a mean transfer efficiency of 12.3% from detritus, and 12.2% from primary producer within the ecosystem. The biomass density of commercially utilized species estimated by the model was 8.7 t·km^-2, and the bioproduction only accounted for 1.81% of the net primary production, which indicated that the system was still in developing status and instable.

Molecular mechanisms of plant resistance to cadmium toxicity

XU Zhenghao^1,2;SHEN Guojun²;ZHU Changqing³;XU Linjuan¹;HE Yong¹; YU Gusong²

2006, 17(06):  1112-1116 . 

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Cadmium (Cd) is a non-essential trace element for plants, and has strong toxicity at low concentrations. It can suppress the elongation growth of plant cell, inhibit oxidative mitochondrial phosphorylation, induce oxidative stress, inhibit the activities of several antioxidative enzymes, affect photosynthesis by inhibiting ferrous reductase or damaging photosynthesis apparatus, and cause the alteration of chromatin and the change of plasma membrane ATPase activity. In response to Cd stress, the cells of cadmium-resistant plant species can produce a number of proteins such as phytochelatins, metallothioneins and stress proteins to detoxify Cd ions, and efficiently repair Cd damage. The plant cells can also resort to other defense systems to detoxify Cd ions, e.g., the immobilization of Cd by cell wall, exclusion of Cd through the action of plasma membrane, compartmentalization of Cd by vacuolar, and release of plant glands. The phytochelatin synthase (PCS) genes of Arabidopsin, wheat and Schizosaccharomyces pombe had been identified by using different approaches, and the metallothioneins (MT) in plants was also identified recently. By introducing animal MT genes, transgenic plants could increase the resistant ability to Cd toxicity. Subjected to Cd, plant cells often start to synthesize stress proteins such as heat shock proteins, and the plants having been transformed the stress protein genes could enhance their resistant capacity to Cd ions. It was reported that zinc (Zn) ion-transporting proteins could also transport Cd ion. Some minor genes not conferring tolerance on their own could modify the major gene(s), and enhance Cd tolerance. Cd detoxification in wild type plants could be a complex phenomenon, probably under polygenic control to Cd, while acute Cd stress seemed to be a simpler mechanism, apparently involving only one or a few specific major genes.

Research advances in thermotolerance regulation of cool-season turfgrass

XU Sheng^1,2; LI Jianlong²;HE Xingyuan¹;CHEN Wei¹

2006, 17(06):  1117-1122 . 

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Among abiotic stresses, high temperature is one of the important ecological factors limiting the growth and development of cool-season turfgrass in the transitional and warm climatic regions, especially during hot summer, which leads to the decline of turf quality, loss of chlorophyll, metamorphism of protein, decrease of photosynthetic activities, and even, cell death. Therefore, how to overcome the difficulty for cool-season turfgrass in spending hot summer successfully, especially in the transitional and warm climatic regions, is a serious problem. Based on the statement of regulation principle in thermotolerance, the research advances in thermotolerance regulation of cool-season turfgrass were reported, including the advances in morphological, ecological, physiological, and biochemical characters in thermotolerance, and the advances in thermotolerance regulation by proper management and regulation measurements such as lowing the soil temperature, application of growth regulators and fertilization, proper clipping, and irrigation.

Application of organic agents in remediation of heavy metals-contaminated soil

SUN Xiaofeng^1,2;WU Longhua¹;LUO Yongming¹

2006, 17(06):  1123-1128 . 

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Organic agents play an important role in the remediation of heavy metals  contaminated soil, and their introduction into practice is a promising strategy to develop an efficient solution for this remediation. This paper summarized the research advances in the application of organic agents to the remediation of heavy metals-polluted soil, including their action mechanisms, advantages and disadvantages, and factors affecting their efficiency. The commonly used organic agents, such as aminopolycarboxylic acid, organic acid, humic acid, biosurfactants, etc., were introduced, and the prospects of organic agents’ application were discussed.

Soil microbial ecological process and microbial functional gene diversity

ZHANG Jing^1,2;ZHANG Huiwen¹;LI Xinyu¹;SU Zhencheng¹;ZHANG Chenggang¹

2006, 17(06):  1129-1132 . 

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Soil microbes in terrestrial ecosystem carry out a series of important ecological functions, such as geo-chemical cycling of elements, degradation of pollutants, and buffering to the acute changes of environment, etc. Soil microbial ecological function has a close relation with soil function, and the changes in the structure and composition of soil microbial populations can directly affect the realization of soil function. Through their produced enzymes, soil microbes take part in a series of metabolic activities, and the functional genes of coded enzymes are the functional markers of microbes. In recent ten years, molecular ecology focusing on the functional gene diversity has been developed rapidly, which gives us a new cut-in point to understand soil microbial ecological function from the point of functional gene. This paper reviewed the research advances in the functional gene diversity correlated to soil microbial ecological function, with the perspectives in this field discussed.

Cold tolerance and its seasonal variation of Catantops pinguis Stal

WANG Shigui¹; ABLIKIM Gulmire^{1, 2}

2006, 17(06):  1133-1136 . 

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By the method of supercooling point (SCP) determination, this paper studied the cold tolerance of Catantops pinguis Stal in different seasons, and the effects of insect body water content, crude fat, total protein and total sugar on it. The results showed that there was a significant seasonal variation in the SCP of C. pinguis. The mean SCP value of fall C. pinguis population was （-23.1 ± 0.2） ℃, while that of post-winter and summer C. pinguis populations was （-19.3 ± 0.1） ℃ and （-4.0 ± 0.1） ℃, respectively. The water content in summer population was significantly higher than that in winter population, but little difference was observed in fall and post-winter populations, indicating that C. pinguis had eliminated the redundantdissociate water during the preparation period for its over-wintering. After winter, the contents of fat and sugar in C. pinguis decreased significantly because the storage of these compounds was expended to maintain the body temperature at winter time, and consequently, resulted in a marked increase of SCP in post-winter population. There was no significant difference in the contents of water and crude fat between female and male C. pinguis, but the total protein content of female C. pinguis was higher than that of male C. pinguis in summer while significantly lower in winter, because large amount of nutrients was expended by the female C. pinguis to form eggs.

Inhibitory effects of natural plant extracts on Verticillium albo-atrum

ZHANG Shuhong;ZHOU Baoli;ZHANG Lei;FU Yawen

2006, 17(06):  1137-1140 . 

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This paper studied the inhibitory effects of 54 kinds of ethanolextracted plant solutions on Verticillium albo-atrum. The results showed that 15 kinds of these extracts could inhibit the growth of Verticillium albo-atrum mycelium, with an inhibitory rate more than 50%, among which, the inhibitory rate of Asarum sieboldii, Coptis chinensis, Magnolia officinalis, Acacia catechu, Sophora flavescens, Glycyrrhiza uralensis, Cnidium monnieri, Platycodon grandiflorum and Allium cepa. extracts was higher than 65%, and that of Cnidium monnieri extract reached 86.84%. A total of 16 kinds of plant extracts decreased the spore germination of V. albo-atrum, with the inhibitory rate higher than 70%, and there were 7 kinds of plant extracts whose inhibitory rate reached 95%. Almost no spore bourgeon was found after treated with Asarum sieboldii, Coptis chinensis, and Magnolia officinalis extracts. The extract of Acacia catechu did not inhibit the growth of mycelium, but restrained the spore germination by 100%. Cnidium monnieri extract could strongly inhibit the growth of mycelium, but had a less effect on spore germination rate (only by 11.3%). The active substances found in natural plant extracts which had the inhibitory effects on pathogen brought us a new and promising method to deal with V. albo-atrum and other vegetable diseases.

Effects of Apatococcus lobatus parasitization on leaf photosynthesis characteristics of orange (Citrus cv. Olinda)

WANG Daping^{1, 2}; ZENG Ming¹; ZHU Jun¹; LI Daogao¹

2006, 17(06):  1141-1144 . 

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With 2-year pot-grown grafted Citrus cv. Olinda as test material, this paper studied the effects of Apatococcus lobatus parasitization on its leaf photosynthesis characteristics. No significant differences were observed between slightly affected and control leaves in their total chlorophyll (Chl a+b) and carotenoid (Car) contents, net photosynthetic rate (P_n), intercellular CO₂ concentration (C_i), primary maximum photochemical efficiency of PS Ⅱ (F_v/F_m), quantum efficiency of noncyclic electron transport of PS Ⅱ (ΦPS Ⅱ), and photochemical quenching (qP), but for medium and severely affected leaves, their Chla+b, Car, P_n,F_v/F_m, ΦPS Ⅱ and qP decreased by 23.85%, 26.49%, 43.3%, 4.5%, 35.1% and 22.5%, and 37.61%, 44.04%, 64.5%, 8.6%, 63.6% and 40.1%, respectively, while C_i increased, with significant differences to the control. It could be concluded that the massive parasitization of A. lobatus caused a stress to orange plant, and non-stomatal limitation was the dominating factor of P_n reduction.

Effects of Larix gmelini aqueous extracts on seed germination and seedling growth of Juglans mandshurica

YANG Lixue

2006, 17(06):  1145-1147 . 

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In this study, Juglans mandshurica seeds were drenched in different concentrations (12.5, 25, 50 and 100 g·kg^-1) aqueous extracts from adult Larix gmelini root, bark, branch and leaf for one week, and cultured in greenhouse in midApril, 2004. The germination rate and germination index were calculated 18 days later, and the seedling’s height and collar diameter were measured on August 1st. The results suggested that 25 g·kg^-1 root and 12.5 g·kg^-1 bark and branch aqueous extracts of L. gmelini could significantly increase the seed germination rate and germination index of J.mandshurica (P＜0.05), and 12.5 g·kg^-1 root and bark aqueous extracts could significantly increase the seedling height and collar diameter (P＜0.05). High concentrations of L. gmelini leaf aqueous extract could significantly promote the seed germination and seedling growth of J. mandshurica, but the promotion effect decreased gradually with decreasing concentration of leaf aqueous extract. The promotion of L. gmelini aqueous extracts to J.mandshurica seed germination and seedling growth might be related to the allelopathy between these two tree species.