Table of Content

18 August 2010, Volume 21 Issue 08

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Articles

Species composition, structure, and spatial distribution of shrubs in broad-leaed Korean pine (Pinus koraiensis) mixed forest in Changbai Mountains.

2010, 21(08):  1899-1906. 

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Based on the shrub census of 600 quadrats  （5 m×5 m） in a 25 hm² plot of broad-leaved Korean pine mixed forest in Changbai Mountains, this paper analyzed the species composition, structure, and spatial distribution of shrubs in the forest. A total of 18 shrub species, including 6435 shrub individuals and 11369 stems, were found in the census, with Philadelphus schrenkii, Corylus mandshurica, and Acer barbinervebeing the dominant species. P. schrenkii had the highest amounts of individuals and stems, occupying 40.6% and 33.4% of the total, respectively. There existed great differences in the clumpy ratio, stem number per clump, crown size, and basal diameter among the shrub species, and the height of different shrub species also varied significantly, with obvious vertical stratification observed in the community. The dominant species P. schrenkii had a wide distribution, while Sorbaria sorbifolia, Spiraea chamaedryfolia, S. salicifoli, and Euonymus pauciflorus had obvious heterogeneous distributions. 

Dynamics of nutrients in an age sequence of Pinus massoniana plantation.

2010, 21(08):  1907-1914. 

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By using a chronosequence approach, this paper studied the nutrients accumulation, allocation, and cycling in 7-, 17-, 31-, and 51-year-old Masson pine plantations, aimed to analyze the dynamics of nutrients in Masson pine plantation at its different developmental stages. The results showed that 1) nutrient accumulation was not synchronized with biomass accumulation, with the accumulation rate of biomass being 3.3, 5.4, 3.3, 3.7, and 9.8 times of that of N, P, K, Ca, and Mg from age 17 to 51, respectively, 2) nutrient allocation to a specific component was related to the growth rate of the nutrient pool in the component, and the nutrient allocation to stem as well as the ratio of nutrient allocation to root/shoot increased with plantation age, and 3) the biomass production per unit nutrient, i.e., nutrient use efficiency, and the nutrient cycling coefficient also increased with plantation age, being higher for 51-year-old plantation than for younger plantations, suggesting that shortening the rotation length could reduce the possibility to raise the nutrient use efficiency. It was suggested that both extending the current rotation length to as long as 50 years and reducing the harvest intensity could be helpful to conserve the nutrients and to maintain long-term productivity.

Climatic suitability of citrus in subtropical China.

2010, 21(08):  1915-1925. 

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By applying the theories of ecological suitability and the methods of fuzzy mathematics, this paper established a climatic suitability model for citrus, calculated and evaluated the climatic suitability and its spatiotemporal differences for citrus production in subtropical China, and analyzed the climatic suitability of citrus at its different growth stages and the mean climatic suitability of citrus in different regions of subtropical China. The results showed that the citrus in subtropical China had a lower climatic suitability and a higher risk at its flower bud differentiation stage, budding stage, and fruit maturity stage, but a higher climatic suitability and a lower risk at other growth stages. Cold damage and summer drought were the key issues affecting the citrus production in subtropical China. The citrus temperature suitability represented a latitudinal zonal pattern, i.e., decreased with increasing latitude; its precipitation suitability was high in the line of “Sheyang-Napo”, medium in the southeast of the line, low in the northwest of the line, and non in high mountainous area; while the sunlight suitability was in line with the actual duration of sunshine, namely, higher in high-latitude areas than in low-latitude areas, and higher in high-altitude areas than in plain areas. Limited by temperature factor, the climatic suitability was in accordance with temperature suitability, i.e., south parts had a higher suitability than north parts, basically representing latitudinal zonal pattern. From the analysis of the interannual changes of citrus climatic suitability, it could be seen that the citrus climatic suitability in subtropical China was decreasing, and had obvious regional differences, suggesting that climate change could bring about the changes in the regions suitable for citrus production and in the key stages of citrus growth. 

Fine root biomass and its nutrient storage in karst ecosystems under different vegetations in Central Guizhou, China.

2010, 21(08):  1926-1932. 

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The degeneration of karst ecosystem is closely associated with the reduction of soil nutrients and fine root biomass, and the retention of soil nutrients is of significance in sustaining ecosystem functioning. To understand the changes in the fine root biomass and soil nutrient retention in degenerated karst ecosystems, a comparative study was conducted with three typical vegetation stands (forest, shrub, and shrub-grass) in Central Guizhou of Southwest China. Soil samples with fine roots were collected from the depths 0-5 cm, 5-10 cm, and 10-15 cm, with the related indices of fine roots and nutrients measured. In the three stands, fine roots dominantly distributed in 0-10 cm soil layer, and decreased sharply with soil depth. The living fine root biomass in 0-10 cm soil layer under forest, shrub, and shrub-grass occupied 83.36%, 86.91%, and 93.79% of the total fine root biomass, and 42.78%, 56.75%, and 53.38% of the total living fine root biomass within the 0-15 cm soil layer, respectively. The fine root biomass of predominant plant species varied with vegetation types. The N and P storage of the living fine roots in 0-5 cm soil layer under forest stand was significantly higher than those under shrub stand and shrub-grass stand, and no significant differences were observed between the latter two stands. However, the N and P storage of the living fine roots in 5-10 cm soil layer under different stands decreased in the order of forest > shrub > shrub-grass (P<0.05). There was a significant positive correlation between the plant aboveground biomass and the living fine root biomass in 0-10 cm soil layer, and a significant negative correlation between the N and P contents of plant leaves and the specific length of living fine roots, illustrating that the nutrient uptake and retention by the living fine roots could have particular importance in the aboveground biomass establishment and ecosystem functioning.

Nutrient concentration and storage in different organs of Eucalyptus under effects of nitrogen topdressing.

2010, 21(08):  1933-1939. 

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A field experiment was conducted to study the effects of nitrogen (N) topdressing on the biomass accumulation and nutrient concentration and storage in different organs of two-year-old eucalyptus. Comparing with the control, N topdressing increased the eucalyptus biomass by 24.2 %. Branch had the highest increment (38.2%), while leaf had the lowest one. The nutrient uptake under N topdressing was improved significantly, with the order of P>K>N>Mg>Ca>Si. Leaf had the highest contents of N, P, Mg, and Si; trunk had the highest storage of K; while branch had the most significant increase of nutrient concentration and storage. The N, P, and K were recycled mainly through internal flux, with 73.8% of N, 79.1% of P, and 72.9% of K in leaf transferred back to the plant before leaf fallen, and the external flux of these three nutrients only occupied 14.8%, 7.7%, and 8.6% of their total storage in the tree, respectively. The Ca, Mg and Si were the external flux elements, especially for Ca. 89.2% of Ca in leaf was cycled in external flux, accounting for 25.9% of its total storage in the tree.

Spatial distribution of Tamarix ramosissima aboveground biomass and water consumption in the lower reaches of Heihe River, Northwest China.

2010, 21(08):  1940-1946. 

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Based on the field observation on the Tamarix ramosissima populations in the lower reaches of Heihe River, the relationship models between the aboveground biomass of T. ramosissima and its morphological features (basal diameter, height, and canopy perimeter) were built. In the mean time, the land use/cover of the study area was classified by the decision tree classification with high resolution image (QuickBird), the distribution of T. ramosissima was extracted from classification map, and the morphological feature (canopy perimeter) of T. ramosissima was calculated with ArcGIS 9.2. On the bases of these, the spatial distribution of T. ramosissima aboveground biomass in the study area was estimated. Finally, the spatial distribution of the water consumption of T. ramosissima in the study area was calculated by the transpiration coefficient (300) and the aboveground biomass. The results showed that the aboveground biomass of T. ramosissima was 69644.7 t, and the biomass per unit area was 0.78 kg·m^-2. Spatially, the habitats along the banks of Heihe River were suitable for T. ramosissima, and thus, this tree species had a high biomass. The total amount of water consumption of T. ramosissima in the study area was 2.1×10⁷ m³, and the annual mean water consumption of T. ramosissima ranged from 30 mm to 386 mm.

Effects of debagging time and picking off leaf on fruit quality of “Red Fuji"|apple.

2010, 21(08):  1947-1952. 

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This paper studied the effects of debagging time and picking off leaves around fruits on the fruit quality and 1-year old shoots stored nutrition of “Red Fuji” apple. Properly advancing debagging time  significantly increased the mean mass, anthocyanin content, and coloration area of the fruits (P＜0.05). Comparing with those of the fruits debagged on September 30, the mean mass, anthocyanin content, and coloration area of the fruits debagged on September 24 increased by 10.98%, 28.15%, and 13.44%, respectively, and the fruit firmness, soluble solid content, and titratable acidity had less differences. When the leaves within 15, 30, and 45 cm away from the fruits were wholly picked off, the light environment around the fruits improved significantly (P＜0.01), with the light intensity increased by 70%, 95%, and 115%, respectively, compared with no leaf picked off treatment. Picking off the leaves within 30-45 cm away from the fruits benefited the fruit coloration and anthocyanin accumulation. No significant effects were observed on the 1-year old shoots stored nutrition and their budding in next year among the treatments of picking off leaves. Advancing debagging time and picking off the leaves within 30-45 cm away from the fruits could improve fruit appearance and quality.

Regeneration of Phyllostachys heteroclada and its relations with rhizome carbon- and nitrogen metabolism.

2010, 21(08):  1953-1958. 

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In order to search for the ways to restrain the flowering process and promote the regeneration of bamboo (Phyllostachys heteroclada), five types of regeneration experiments were conducted, including 1) harvesting all the bamboos in the first year and the flowered bamboos in the next year all at the beginning stage of florescence, 2) harvesting the flowered bamboos at the beginning stage of florescence in two consecutive years, 3) harvesting the fully flowered bamboos in the first year and the bamboos at the beginning stage of florescence in the next year, 4) fertilizing the bamboo floor before growing season in consecutive two years, and 5) no any manipulation. In each of the cases, the carbon- and nitrogen metabolism and related enzyme activities in bamboo rhizome were studied. The results showed that treatment 1 had the best effect, which resulted in the greatest number (207) of new shoots produced and with the highest survival rate (69.33%), and had the most obvious effect on restraining bamboo flowering and promoting regeneration. Also, it produced the highest contents of soluble sugar (10.89%) and total sugar (20.39%), the highest total sugar to total nitrogen ratio (34.56), and the highest glutamine synthetase activity (104.52 mg·g^-1·h^-1) in bamboo rhizome. These findings demonstrated that the carbon- and nitrogen metabolism in the rhizome had definite relationships with the flowering process and regeneration of bamboo, and the rhizome growth played a critical role in bamboo propagation.

Effects of fertilization on Casuarina equisetifolia seedlings total phenolics and extractable condensed tannin contents.

2010, 21(08):  1959-1966. 

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This paper studied the effects of nitrogen-and phosphorus fertilization on the total phenolics (TP) and extractable condensed tannin (ECT) contents in the branchlets of Casuarina equisetifolia seedlings, aimed to approach the nutrient effect on tannin production. Under nitrogen fertilization, the TP and ECT contents decreased significantly, which supported the hypotheses of carbon-nitrogen balance (CNB) and growth-differentiation balance (GDB), but the plant nitrogen content had less change, resulting in the decrease of TP/N and ECT/N ratios. Phosphorus fertilization had no significant effects on the TP and ECT production. With prolonged treatment time, the TP content in the branchlets of C. equisetifolia seedlings increased by 9.91%-14.32%, but the ECT content decreased by 14.32%-298.88%. The TP and ECT had opposite relationships with organic matters content, showing that different types of tannin had different biosynthetic pathways. However, both TP and ECT had no significant correlation with nitrogen content, and thus, the protein competition model (PCM) was not supported. Under nutrient-poor condition, the TP/N and ECT/N ratios were relatively high, which would be beneficial for the improvement of defense ability, the decrease of litter decomposition ratio and nutrient loss, and the maintenance of high productivity of C. equisetifolia plantations.

Spatial patterns of seed dispersal in Hemiptelea davidii woodland in Keerqin sandy land, China.

2010, 21(08):  1967-1973. 

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In order to reveal the space expansion potential of Hemiptelea davidiiwoodland in Keerqin sandy land in China, the quantitative spatial characteristics of the seed rain in the understory and at the woodsides, as well as the seed dispersal patterns at the woodsides and of the isolating trees, were analyzed through survey on sequential sampling away from seed source in different directions at the woodsides and isolating trees and random sampling in the understory. The results showed that among three sampling plots, the average density of the seed rain in the understory was the highest (13732.5±3106.2 seeds· m^-2). For isolating trees, the seed rain had the highest density (5449.4±1429.3 seeds·m^-2) in southeast transect, being significantly higher than that in other directions, and the lowest one (650.2±631.6 seeds·m^-2) in the northwest transect, being significantly lower than that in other directions. At the woodsides, the seed rain density was significantly higher in the east and south transects than in the west and north transects. The variation of the seed density was greater, with the variation coefficient being 25.7%-106.3% in different directions in the two plots of isolating trees and woodsides. Same as other anemochorous plants, H. davidiihad the characteristics of seed dispersal away from the seed source. In the eight sampling transects, there existed diversity in the patterns of the seed dispersal away from the seed source in per unit area and in accumulated area, including linear, power, exponential, quadratic parabola, and logarithmic functions. It was suggested that the space expansion potential of H. davidii woodland in Keerqin sandy land would be greater in more freq uency down wind directions such as the south, southeast, and east than in more frequency upwind directions such as the north, northwest, and west.

Effects of zinc-and iron deficiency on physiological indices, mineral contents, and leaf ultrastructure of Poncirus trifoliata.


2010, 21(08):  1974-1980. 

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By using hydroponics, this paper studied the physiological responses of trifoliate orange (Poncirus trifoliata)seedlings to the deficiency of zinc (0 μmol·L^-1Zn²⁺) and/or iron (0 μmol·L^-1Fe-EDTA). The deficiency of both Zn and Fe decreased the plant biomass and root viability, and increased the leaf-and root SOD activity significantly. Zinc deficiency increased the leaf-and root POD significantly, while Fe deficiency had an adverse effect. The root CAT activity increased significantly under Zn deficiency, but had less difference with the control under Fe deficiency. Fe and Zn deficiency induced a significant decrease of root potassium (K), magnesium (Mg), and phosphorus (P) contents and of shoot K content, respectively, but resulted in a significant increase in the root-and shoot Zn and Cu contents and in the root Fe and Mn contents and shoot Mn content, respectively. Ultrastructural observation of leaf structure and chloroplast showed that under Fe deficiency, the organelle was damaged seriously, which was revealed by the vacuolization of chloroplast and mitochondria, vague chloroplast membrane and thylakoid lamella, drastic increase of platoglobuli number, and absence of starch grain in the chloroplast. Under Zn deficiency, the thylakoid lamella of chloroplast was loosely distributed with less lamella, but the platoglobuli number was increased.

Soil organic carbon density of Eucalyptus plantations in Guangdong Province of China and related affecting factors.

2010, 21(08):  1981-1985. 

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Soil samples were collected from the Eucalyptus  plantations in the north, east, and west Guangdong and Pearl River Delta region to study their organic carbon content and density, and the main factors affecting the organic carbon density. In the plantations, the soil organic carbon content and density in A and B horizons were significantly different, with the values of (23.94±2.97) g·kg^-1and (9.68±1.05) g·kg^-1, and (27.64±7.72) t·hm^-2 and (108.36±9.37) t·hm^-2, respectively. In 0-50 cm soil layer, the organic carbon density was 66.72±6.53 t·hm^-2, being slightly higher than that in Masson pine and Chinese fir plantations in Guangdong. In both A and B horizons of Eucalyptu plantations, soil organic carbon density was significantly positively correlated with altitude, soil total porosity, capillary porosity, capillary moisture capacity, and total nitrogen content. Soil capillary porosity, capillary moisture capacity, and pH value were the main factors affecting the soil organic carbon density.

Evolvement of soil quality in salt marshes and reclaimed farmlands in Yancheng coastal wetland.

2010, 21(08):  1986-1992. 

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Through vegetation investigation and soil analysis, this paper studied the evolvement of soil quality during natural vegetation succession and after farmland reclamation in the Yancheng coastal wetland of Jiangsu Province. Along with the process of vegetation succession, the soil physical, chemical, and biological properties in the wetland improved, which was manifested in the improvement of soil physical properties and the increase of soil nutrient contents, microbial biomass, and enzyme activities. Different vegetation type induced the differences in soil properties. Comparing with those in salt marshes, the soil salt content in reclaimed farmlands decreased to 0.01-0.04%, the soil microbial biomass and enzyme activities increased, and the soil quality improved obviously. The soil quality index (SQI) in the wetland was in the order of mudflat (0.194) < Suaeda salsa  flat (0.233) < Imperata cylindrica flat (0.278) < Spartina alterniflora flat (0.446) < maize field (0.532) < cotton field (0.674) < soybean field (0.826),suggesting that positive vegetation succession would be an effective approach in improving soil quality.

Effects of different peony cultivars on community structure of arbuscular mycorrhizal fungi in rhizosphere soil.

2010, 21(08):  1993-1997. 

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This paper studied the community structure of arbuscular mycorrhizal (AM) fungi in the rhizosphere soil of different peony (Paeonia suffruticosa) cultivars grown in Zhaolou Peony Garden of Heze in Shandong Province. A number of parameters describing this community structure, e.g., spore density, species- and genera composition, species richness, distribution frequency, species diversity indices, and Sorenson’s similarity coefficient, were examined. The species- and genera composition, species richness, and distribution frequency of AM fungi in rhizosphere soil varied with planted peony cultivars. A total of 10 AM fungal species were isolated from the rhizosphere soil of cultivars ‘Fengdan’ and ‘Zhaofen’, 9 species from the rhizosphere soil of ‘Wulong pengsheng’ and ‘Luoyang red’, and 8 species from the rhizosphere soil of ‘Hu red’. The spore density was the highest (59 per 50 g soil) in the rhizosphere soil of ‘Fengdan’, but the lowest (47 per 50 g soil) in the rhizosphere soil of ‘Hu red’; the species diversity index was the highest (1.89) in the rhizosphere soil of‘Zhaofen’, but the lowest (1.71) in the rhizosphere soil of ‘Hu red’; and the mycorrhizal colonization rate was the highest (63.6%) in rhizosphere soil of ‘Fengdan’ and ‘Hu red’, but the lowest (52.7%) in the rhizosphere soil of ‘Wulong pengsheng’. The Sorenson’s similarity coefficient of AM fungal species composition in the rhizosphere soil among the test cultivars ranged from 0.71 to 0.95, being the highest between ‘Wulong pengsheng’and ‘Fengdan’, and the lowest between ‘Luoyang red’ and ‘Hu red’. It was concluded that the gene type of peony could change the community structure of AM fungi in rhizosphere soil.

Aluminum-tolerant characteristics of different Chamaecrista genotypes.

2010, 21(08):  1998-2003. 

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A hydroponic culture experiment was conducted to study the responses of 40 Chamaecrista varieties (lines) to 120 mg·L^-1 of A1³⁺, with the correlations between the relative tolerance values of various characters of different genotypes and the comprehensive evaluation coefficient compared. Among the characters of the genotypes, the relative plant height, relative root dry mass, relative shoot dry mass, and relative root activity could be selected as the important indices for screening the Al-tolerant genotype of Chamaecrista. In the test 40 Chamaecrista varieties (lines), the 86134R2, 2208, 3170, 316, 2211,and 2232 had stronger Al-tolerant capability, belonging to Al-tolerant genotype, whereas the 34721R1, 92985, and 3184 had weaker Al-tolerant capacity, belonging to Al-sensitive genotype.

Effects of drought stress on photosynthesis capability of Spiraea fritschiana and Spiraea bunmalba‘Goldmound’.

2010, 21(08):  2004-2009. 

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In this paper, Spiraea fritschiana and Spiraea bunmalba‘Goldmound’ were treated with mild, moderate, and severe drought to study the dynamic changes of their photosynthesis capability, and two-dimensional electrophoresis and mass spectrometry were adopted to analyze and identify the differences in the protein expression of the two species before and after the treatments, and the physiological mechanisms inducing the changes of the photosynthesis capability. Drought treatments had significant effects on the photosynthesis capability of the two species. Under drought stress, the maximum photosynthetic rate, light compensation point, and light saturation point decreased gradually, suggesting that the responses of the two species to drought stress were progressive. The two species presented stronger recovery capability after the mild and moderate stresses, but weaker recovery capability after severe stress. After the inducement of drought stress, the weaker drought resistant S. bunmalba‘Goldmound’ had six protein spots lost, eleven new protein spots appeared, thirteen protein spots up-regulation expression, and four protein spots down-regulation expression. All of the proteins were low molecular weight acidic proteins, of which, there were three kinds of different proteins that had been induced expression by drought and were the oxygen-enhanced protein factor 1 and 2 and the degradation fragments of large subunit 1,5-ribulose bisphosphate carboxylase/oxygenase. The drought- resistant difference of the two Spiraea  species was related to the changes of their photosynthesis capability during drought stress.

Dynamics of active organic carbon in a paddy soil under different rice farming modes.

2010, 21(08):  2010-2016. 

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A field experiment was conducted to study the dynamics of dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) in a paddy soil under integrated rice-duck farming (RD), intermittent irrigation (RW), and conventional flooded irrigation (CK), the three rice farming modes typical in southern China. Under these three farming modes, the soil DOC and MBC contents reached the highest during the period from rice booting to heading, while the soil ROC content had less change during the whole rice growth period. Two-factor variance analysis showed that soil MBC was  greatly affected by rice growth stage, soil DOC was greatly affected by rice growth stage and farming mode, and soil ROC was mainly affected by farming mode. Comparing with CK, RD  significantly increased the soil DOC and ROC contents and their availability, while RW  significantly decreased the soil DOC content and its availability but increased the soil ROC content and its availability. No significant differences were observed in the soil MBC and microbial quotient among RD, RW, and CK.

Effects of nitrogen form and its supply position on maize seedling growth under partial root-zone water stress.

2010, 21(08):  2017-2024. 

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A split root system consisting of two compartments was installed to study the effects of nitrogen form and its supply position on the growth of maize seedlings under partial root-zone water stress. Polyethylene glycol (PEG 6000) was added to the nutrient solution in one compartment to simulate partial root-zone water stress, while nitrogen was set as three forms (nitrate nitrogen, ammonium nitrogen, and their 1∶1 mixture) and supplied to just one compartment (water-stressed or non-water-stressed compartment). Photosynthetic and other physiological indices were examined.  Comparing with the nitrogen supplied to waterstressed compartment, the nitrogen supplied to non-water-stressed compartment improved the photosynthetic rate (P_n), maximum net photosynthetic rate (P_max), light saturation point (LSP), CO₂ saturation point (CSP), chlorophyll content, root activity, nitrogen uptake, and biomass accumulation, but reduced the photorespiration rate (R_p), CO₂ compensation point (CCP), abscisic acid (ABA) concentration in xylem sap, and nitrogen-and water use efficiency of the plants. Supplying nitrate nitrogen or its mixture with ammonium nitrogen improved the P_n, P_max, LSP, CSP, nitrogen uptake, and biomass accumulation, but reduced the CCP, R_p, ABA concentration in xylem sap, and nitrogen- and water use efficiency of the plants, compared with supplying ammonium nitrogen. All the results showed that supplying same nitrogen forms to non-water-stressed compartment was more beneficial to the plant growth but disadvantageous to the plant nitrogen-and water use, compared with supplying the nitrogen forms to water-stressed compartment, and supplying nitrate nitrogen or its mixture with ammonium nitrogen -promoted- the plant growth but reduced the plant nitrogen- and water use, compared with supplying ammonium nitrogen.

Effects of nitrogen fertilization on soil respiration during maize growth season.

2010, 21(08):  2025-2030. 

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In order to understand how nitrogen (N) fertilization affects soil respiration, a pot experiment with splitting-root compartment and by root-cutting was conducted in a greenhouse. The experiment had four treatments, i.e., unplanted and N-unfertilized (CKO), unplanted but fertilized with 150 mg N·kg^-1 (CKN), planted maize (Zea mays L.) but N-unfertilized (MO), and planted maize and fertilized with 150 mg N·kg^-1(MN). Soil respiration, soil basal respiration, root respiration, and rhizospheric microbial respiration were measured simultaneously. In unplanted soils (treatments CKO and CKN), soil respiration rate (soil basal respiration) ranged from 13.41 to 77.27 mg C·m^-2·h^-1, and N fertilization had less effect; while in planted soils, the averaged soil respiration rate in treatment MN amounted to 138.54 mg C·m^-2·h^-1, and was 17.7% higher (P<0.05) than that in treatment MO. This increment mainly occurred at tasselling and flowering stages. During maize growth season, the contribution of soil basal respiration, root respiration, and rhizospheric microbial respiration to soil respiration in treatments MN and MO was 36.2%, 45.9%, and 17.9%, and 35.5%, 36.9%, and 37.6%, respectively.

Effects of sprinkler irrigation amount on winter wheat growth, water consumption, and water use efficiency.

2010, 21(08):  2031-2037. 

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In 2006-2008, a field experiment was conducted at the Tongzhou Experimental Base for Water-Saving Irrigation Research, Chinese Academy of Sciences, Beijing, aimed to study the effects of sprinkler irrigation amount on the growth, grain yield, water consumption, and water use efficiency of winter wheat. Different treatments were installed, with the irrigation amounts expressed by the multiples of the evaporation (E) from a standard 20cm diameter pan placed above winter wheat canopy. The grain yield was the highest in treatment 0.75 E in 2006-2007 and in treatment 0.625 E in 2007-2008. In treatments with irrigation amount less than 0.25 E, winter wheat growth was subjected to water stress, and the yield loss was larger than 25%. The water consumption of winter wheat in the two growth seasons was in the range of 219-486 mm, and increased with increasing irrigation amount. The relationships between the grain yield and the water consumption and water use efficiency could be described by quadratic function. Sprinkler irrigation with an amount of 0.50-0.75 E was recommended for the winter wheat growth after its turning green stage in Beijing area.

Effects of root-knot nematodes on cucumber leaf N and P contents, soil pH, and soil enzyme activities.

2010, 21(08):  2038-2044. 

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A pot experiment was conducted to study the effects of inoculation with root-knot nematodes on the cucumber leaf N and P contents, and the rhizospheric and non-rhizospheric soil pH and enzyme activities. The rhizospheric soil pH didn’t have a significant decrease until the inoculation rate reached 6000 eggs per plant. With the increase of inoculation rate, the leaf N and P contents, rhizospheric soil peroxidase activity, and rhizospheric and non-rhizospheric soil polyphenol oxidase activity all decreased gradually, rhizospheric soil catalase activity was in adverse, non-rhizospheric soil pH decreased after an initial increase, and non-rhizospheric soil catalase activity had no regular change. After inoculation, rhizospheric soil urease activity decreased significantly, but rhizospheric and non-rhizospheric soil phosphatase activity and non-rhizospheric soil peroxidase activity only had a significant decrease under high inoculation rate. In most cases, there existed significant correlations between rhizospheric soil pH, enzyme activities, and leaf N and P contents; and in some cases, there existed significant correlations between non-rhizospheric soil pH, enzyme activities, and leaf N and P contents.

Responses of Rubisco and Rubisco activase in cucumber seedlings to low temperature and weak light.

2010, 21(08):  2045-2050. 

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Using ‘Jinyou 3’ cucumber seedlings as test materials, this paper studied their photosynthetic rate (P_n), Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase (RCA) activities, and gene expression of Rubisco and RCA under optimal temperature and weak light (WL: 25 ℃/18 ℃, 100 μmol·m^-2·s^-1), suboptimal temperature and weak light (ST+WL: 18 ℃/12 ℃, 100 μmol·m^-2·s^-1), and low temperature and weak light (LT+WL: 10 ℃/5 ℃, 100 μmol·m^-2·s^-1). Comparing with the control (25 ℃/18 ℃, 400 μmol·m^-2·s^-1), treatments WL, ST+WL, and LT+WL all led to a remarkable decrease in leaf area and dry matter mass. At initial stage, the P_n, Rubisco activity, rbcL and  rbcS expression, RCA activity, and CsRCA expression in the three treatments declined by a big margin; 5-7 days later, these parameters tended to be less changed in treatment WL, ascended slowly in treatment ST+WL, and decreased continuously in treatment LT+WL. These results suggested that the photosynthetic apparatus of test cucumber seedlings could gradually adapt to weak light or suboptimal temperature and weak light. The Rubisco and RCA activities and the gene expression of Rubisco and RCA showed the similar responses to low temperature and weak light as the P_n, suggesting that the decline in Rubisco and RCA activities and gene expression in cucumber seedlings under low temperature and weak light  could be the important reason leading to the decrease of P_n.

Effects of grafting on root polyamine metabolism of cucumber seedlings under copper stress.

2010, 21(08):  2051-2056. 

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By the method of hydroponic culture, and taking Cucurbita ficifolia B. as rootstock, this paper studied the effects of grafting on the root polyamine metabolism of cucumber seedlings under copper stress. The results showed that under copper stress, the root activities of cucumber seedlings were inhibited, and electrolyte leakage increased, with these changes being significantly lower for grafted than for ungrafted cucumber seedlings. In addition, the contents of free spermidine and spermine, and of conjugated and bound polyamines were significantly higher in grafted than in ungrafted seedling roots, while the free putrescine content and the ratio of free putrescine to polyamines were on the contrary. Comparing with those in ungrafted cucumber seedlings, the root arginine decarboxylase (ADC), ornithine decarboxylase (ODC), and S-adenosylmethionine decarboxylase (SAMDC) activities in grafted cucumber seedlings were higher, while the diamine oxidase and polyamine oxidase activities were significantly lower. All of these indicated that under copper stress, the synthesis of polyamine in grafted seedling roots was increased, while the degradation of polyamine was decreased, resulting in a higher accumulation of polyamine in the roots, and the increase of the tolerance of cucumber seedlings to copper stress.

Effects of simulated acid rain on oilseed rape (Brassica napus) physiological characteristics at flowering stage and yield.

2010, 21(08):  2057-2062. 

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A pot experiment was conducted to study the effects of different acidity simulated acid rain on the physiological characteristics at flowering stage and yield of oilseed rape (B. napus cv. Qinyou 9). Comparing with the control (pH 6.0), weak acidity (pH=4.0-5.0) simulated acid rain stimulated the rape growth to some extent, but had less effects on the plant biomass, leaf chlorophyll content, photosynthetic characteristics, and yield. With the further increase of acid rain acidity, the plant biomass, leaf chlorophyll content, photosynthetic rate, antioxidative enzyme activities, and non-enzyme antioxidant contents all decreased gradually, while the leaf malonyldialdehyde (MDA) content and relative conductivity increased significantly. As the results, the pod number per plant, seed number per pod, seed weight, and actual yield decreased. However, different yield components showed different sensitivity to simulated acid rain. With the increasing acidity of simulated acid rain, the pod number per plant and the seed number per pod decreased significantly, while the seed weight was less affected.

Effects of soil, climate, and their interaction on some neutral volatile aroma components in flue-cured tobacco leaves from high quality tobacco planting regions of Hunan Province.

2010, 21(08):  2063-2071. 

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A pot experiment with the soils from Yongzhou, Liuyang, and Sangzhi, the high-quality tobacco planting regions of Hunan Province, was conducted to study the effects of climate, soil, and their interaction on some neutral volatile aroma components in flue-cured tobacco leaves. The contents of test neutral volatile aroma components in the flue-cured tobacco leaves were of medium variation, and the variation intensity was decreased in the order of dihydroactinolide, damascenone, furfural, total megastigmatrienone, and β-ionone. Climate, soil, and their interaction affected the neutral volatile aroma components in different degrees. The furfural content was most affected by climate, the damascenone content was most affected by climate and by soil, the total megastigmatrienone and β-ionone contents were most affected by the interaction of soil and climate, while the dihydroactinolide content was less affected by soil, climate, and their interaction. The contribution of climate, soil, and their interaction to the contents of the five aroma components was 40.82%, 20.67%, and 38.51%, respectively. During different growth periods of tobacco, different climate factors had different effects on the neutral volatile aroma components. The rainfall, cloudiness, and mean air temperature at rooting stage, the diurnal temperature amplitude, sunshine time, and evaporation at vigorous growth stage, and the rainfall, evaporation, and mean air temperature at maturing stage were the top three climate factors affecting the contents of the neutral volatile aroma components in flue-tobacco leaves. For the soil factors, the available potassium, available phosphorus, and pH were the top three factors affecting the contents of the five components.

Effects of light intensity on photosynthesis and dry matter production of flue-cured tobacco at its seedling stage.

2010, 21(08):  2072-2077. 

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Taking flue-cured tobacco Yunyan 87 as test material, this paper studied its photosynthesis and dry matter production at seedling stage under 100%, 88%, 72%, and 62% natural light intensities. At noon of sunny days, 100% natural light intensity inhibited the photosynthesis, while proper shading (88% natural light intensity) could eliminate the inhibition, and the daily photosynthesis was significantly higher than other treatments. Shading reduced the light saturation point and compensation point, enhanced the apparent quantum yield of photosynthesis and the net photosynthetic rate under weak light, increased the chlorophyll a and chlorophyll b contents, but decreased the chlorophyll a/b and cartenoids contents. Under 88% natural light intensity, tobacco seedlings had higher light saturation point, lower compensation point, higher suitability to the change of light intensity, and higher photosynthetic potentiality. 100% natural light intensity was more advantageous to the transfer of dry matter and soluble sugar to stem, while 88% natural light intensity was more beneficial to the transfer of dry matter and soluble sugar to root. Under the conditions of this experiment, proper shading (88% natural light intensity treatment) could improve the seedling quality of flue-cured tobacco.

Effects of long-term fertilizations on microbial biomass C and N and bacterial community structure in an aquic brown soil.

2010, 21(08):  2078-2085. 

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Taking a long-term field experiment on an aquic brown soil in the Shenyang Ecological Station of Chinese Academy of Sciences as a platform, the methods of traditional chloroform fumigation and modern PCR-DGGE were adopted to study the effects of different fertilizations on the changes of soil microbial biomass and bacterial community structure. During the whole period of the experiment, there was a similar trend in the dynamic changes of soil microbial biomass C and N. Long-term application of organic manure increased the soil organic C and the soil microbial biomass C and N significantly, while long-term application of chemical fertilizers had significant negative effects on the soil pH and soil microbial biomass C and N. The DGGE patterns showed that under different fertilizations, the majority of soil bacterial 16S rDNA bands were the same, 18 of the 28 bands being common, suggesting that the bacterial populations in test soil were more stable, but their numbers were affected by different fertilizations. Long-term application of organic fertilizer could promote the diversity of the bacterial community structure in aquic brown soil, while the application of chemical fertilizers was in adverse.

Effects of organic fish protein liquid fertilizer on enzyme activities and microbial biomass C and N in a silt soil.

2010, 21(08):  2086-2091. 

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By the method of thermostatic culture, this paper studied the effects of different application rates (0.5, 1.5, and 2.5 ml·kg^-1) of organic fish protein liquid fertilizer on the enzyme activities and microbial biomass C and N in a silt soil, and the relationships between these parameters and soil nutrient contents. Under the application of the liquid fertilizer, soil pH varied in the range of 7.07-7.31, but had no significant difference from the control. With the increasing application rate of the liquid fertilizer, the activities of soil phosphatase, urease, and protease, as well as the soil biomass C and N, all increased significantly, and the increment was 127, 190 and 196%, 39.81, 78.06 and 173.24%, 56.37, 108.29 and 199.98%, 167, 395 and 474%, and 121, 243 and 406%, respectively, compared with the control. The peak time of the soil urease and protease activities and microbial biomass C and N differed with the fertilization treatments. Soil phosphase, urease, and protease activities and microbial biomass C and N were significantly positively correlated with soil nutrient contents, suggesting that applying organic fish protein liquid fertilizer to silt soil could improve soil microbial growth and enzyme activities, and accordingly, promote the decomposition and transformation of soil organic matter and the release of soil available nutrient elements.

Potential of organic manures nutrient resources and their environmental risk in China.

2010, 21(08):  2092-2098. 

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Based on the data from China Agriculture Yearbook2006 and other documents, the amountsof crop straws and of the excreta from human, livestock, and poultry in China in 2005 were estimated, with the potential and the environmental risk of their nutrient resources analyzed. In 2005, the total amount of crop straws in this country was 643 million tons, and that of the excreta from human, livestock, and poultry was 4625 million tons. The amounts of N, P₂O₅, and K₂O from the straws and the excreta were 28.24, 12.82, and 29.48 million tons, being 1.08, 0.86, and 4.56 times of the inputs from chemical fertilizers in the same year, respectively. There was a great regional difference in the distribution of the organic manures nutrient resources. The total amount of N, P₂O₅, and K₂O in the excreta was more than 4 million tons in Henan, Shandong, and Sichuan provinces, but less in Beijing, Tianjin, Shanghai, and northwest China, while the total amount of these nutrients in crop straws was more than 1.5 million tons in Henan and Shandong provinces, the main grain production areas, but less in northwest China. The per unit farmland load of N, P₂O₅, and K₂O from the excreta was the highest (787.26 kg·hm^-2) in Beijing, followed by in Tianjin (515.31 kg·hm^-2) and Shanghai (505.35 kg·hm^-2), where the environmental risk could be more serious.

Spatiotemporal evolution characteristics of late spring cold in Guizhou Province under global climate change.

2010, 21(08):  2099-2108. 

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Based on the 1959-2007 observation data of daily mean temperature from 19 meteorological stations in Guizhou Province, and combining with the late spring cold (LSC) intensity index and disaster grade division standard, this paper analyzed the spatiotemporal evolution characteristics of LSC, including LSC occurrence frequency, ratio of LSC-occurring stations to all stations, decadal variation, abrupt climate change, and periodic variation, in the province. In 1959-2007, the occurrence frequency of no LSC in the province was the highest, followed by serious LSC, and that of medium and slight LSC was approximately the same. Under the background of global warming, the ratio of medium LSC-occurring stations to all stations had the most obvious variation, with the climatic trend reached 1.4%·（10 a）^-1, while the ratios of no LSC-, slight LSC-, and serious LSC-occurring stations all showed an appreciably decreasing trend. The LSC intensity in the province was the highest in the 1990s, followed by in the 1980s, 1960s, 1970s, and 2000-2007. In the province, the LSC intensity showed an increasing trend in west and northwest high altitude areas, central area, and north area, but an appreciably decreasing trend in east and south areas. In the west, northwest, north, and central areas of the province, LSC intensity had a mutation from low to high in 1975. The LSC in the province had an obvious periodical variation, with the inter-annual period being mainly 2-4 years, and the decadal periods being mainly 13-15 years and 27-29 years.

Spatio-temporal variations of vegetation cover in northern Shaanxi Province under the background of ecological restoration.

2010, 21(08):  2109-2116. 

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Based on the 2000-2008 MODIS-NDVI images and using dimidiate pixel model, a dynamic evaluation was made on the vegetation coverage in northern Shaanxi Province, one of the ecologically fragile area in China, under the backgrounds of returning farmland to forestland and grassland and of the integrated management of soil and water loss. In 2000-2008, the vegetation coverage in the study area fluctuated within a year, being the highest in August and the lowest in March, and showed an increasing trend from the northwest to the southeast. The annual maximum vegetation coverage had a pronounced increase, but the area of medium and high coverage increased while that of low coverage decreased. The increased area of vegetation coverage occupied more than half of the study area, especially in the northeast. Climate features and human activities were the main causes inducing the pronounced increase of vegetation coverage, reflecting to a certain extent the effectiveness of ecological restoration efforts. The dimidiate pixel model based on the MODISNDVI images could well and truly simulate the spatiotemporal variation trend of the vegetation cover in northern Shaanxi, and be applicable to quantitatively estimate and evaluate the effectiveness of vegetation restoration at regional scale.

Forest canopy leaf area index in Maoershan Mountain: Ground measurement and remote sensing retrieval.

2010, 21(08):  2117-2124. 

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Leaf area index (LAI) is one of the most important structural parameters of terrestrial ecosystem, while the remote sensing retrieval  and the ground optical instrument measurement  and based on canopy gap modelare the effective approaches to rapidly obtain LAI. However, these two approaches can only acquire effective LAI(LAI_e), due to the clumping of vegetation canopy. Taking the experimental forest farm of Northeast Forestry University at Maoershan Mountain in Heilongjiang Province of Northeast China as study site, this paper measured the forest canopy LAI_e by LAI2000, and estimated the LAI by the combination of TRAC (tracing radiation and architecture of canopies) measurement of foliage clumping index. A LAI remote sensing retrieval model was constructed through the analysis of the relationships between different vegetation indices calculated from Landsat5-TM and measured LAI_e. The results showed that at the study site, the LAIof broad leaved forests was close to the LAI_e, but the LAIof needle leaved forests was 27% larger than the LAI_e. Reduced simple ratio index (RSR) had the highest relationship with measured LAI_e (R²=0.763, n=23), which could be used as the best predictor of LAI. The LAI at study site increased rapidly with increasing elevation when the elevation was below 400 m, but had a slow increase when the elevation was from 400 m to 750 m. When the elevation was above 750 m, the LAI decreased. There was a significant correlation between the forest canopy LAI and aboveground biomass.

Characteristics of soil nematode community along an age sequence of sandy desert soil cultivation in a marginal oasis of middle reaches of Heihe River.

2010, 21(08):  2125-2131. 

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This paper studied the characteristics of soil nematode community following the conversion of native sandy desert soil to irrigated farmland in a marginal oasis of the middle reaches of Heihe River basin, aimed to approach the bioindicating function of soil nematodes in soil evolution process. A total of 27921 soil nematode individuals were captured, belonging to 25 families and 34 genera. The total number of nematodes increased gradually with increasing age of cultivation. At all sampling sites, bacterivores and plant parasites were the dominant trophic groups, and made up the main parts of nematode community in oasis farmland. Through the analysis of the evenness index (J) and dominance index (λ) of nematode community, the ecosystems were found  to be fragile for the farmlands having cultivated for 0, 10, and ＞50 years. The maturity index MI_2-5and MMI decreased with increasing cultivation age, suggesting that the practice of agricultural use enhanced the disturbance on farmland. The soil properties changed significantly after 10 years of cultivation, which was at a significant change stage for the structure stability of soil ecosystems. The characteristics of soil nematode community could be used as the bioindicator of soil evolution following the conversion of native desert soil to irrigated farmland.

Ecological characteristics of macrobenthos communities in Chaohu basin in spring and their relationships with environmental factors.

2010, 21(08):  2132-2139. 

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By the method of field investigation in combining with cluster analysis, multi-dimensional scaling analysis and canonical correspondence analysis, and using the indices of Shannon, Pielou, and Margalef, this paper studied the community structure and biodiversity of macrobenthos in the Chaohu basin in spring, and their relationships with environmental factors. A total of 23 macrobenthos species were collected, among which, six species (26.1% of total) were annelids, eight species (34.8%) were arthropods, and nine species (39.1%) were mollusks. The dominant species were Limnodrilus hoffmeisteri, Branchiura sowerbyi，and Bellamya aeruginosa, and their distribution had obvious spatial heterogeneity. The upper reaches of the rivers inside and out of Chaohu Lake had the highest macrobenthos biodiversity, followed by the Chaohu Lake and its estuary, and the lower reaches of the rivers inside and out of Chaohu Lake. The spatial distribution of the macrobenthos was also affected by various environmental factors, among which, Chl a and NO₃^- were the main ones.  

Standing crop and spatial distribution of meiofauna in Yellow Sea at late stage of Enteromorpha prolifera bloom in 2008.

2010, 21(08):  2140-2147. 

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An investigation was made on the standing crop, spatial distribution, sediment environment of meiofauna at 33 stations (including 22 stations in cold water mass area and 9 stations in Enteromorpha prolifera bloom area) in the Yellow Sea at the late stage of E. prolifera bloom in summer 2008. In this southern Yellow Sea area which was seriously impacted by the green algal bloom, the silt and clay contents in the sediments in 2008 had an obvious increase, compared with those in 2007, and the sediment chlorophyll a and phaeophytin a contents in 2008 did not show obvious changes in cold water mass area but distinctly decreased in southern Jiangsu inshore area and Yangtze River estuary. Within the total 16 meiofaunal groups sorted, no marked variation was observed in their vertical distribution and in the contribution of each group to the total meiofauna. In 2008, the average abundance of meiofauna was (1375 ± 793) ind·10 cm^-2, and the biomass was (1203 ± 707) μg·10 cm^-2, both of which were decreased by about 1/3, compared with those in 2007. The meiofaunal standing crop was decreased more obviously in the stations heavily affected by the E. prolifera bloom, while that in the Yellow Sea cold water mass area was slightly increased, resulting in an unusual trend of meiofaunal standing crop decreasing from the central area of cold water mass to the inshore area in the southern Yellow Sea. By contrast, and as usual, the meiofaunal standing crop was increased from the cold water mass area to the inshore area in the northern Yellow Sea. Statistical analyses suggested that only the meiofaunal abundance had positive correlation with the salinity in the stations heavily affected by the green algal bloom. Our study indicated that macroalgal bloom obviously inhibited the standing crop of meiofauna in the inshore area. The decrease was not due to the deficiency of food concentration, but likely caused by the deposition and degradation of the E. prolifera bloom.

Increasing pattern of phytoplankton biomass with species richness and tests of sampling and complementary effects.

2010, 21(08):  2148-2153. 

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A total of eighteen common phytoplankton species in China coastal waters were divided into different assemblages to investigate the increasing pattern of the assemblage biomass with species richness. The sampling effect was studied by multiple analysis of variance (MANOVA) method, and the complementary effect was explored by over-yielding analysis, relative yield total (RYT) index, and subset approach. It was shown that the increasing pattern of assemblage biomass with species richness was not unitary. When the species number was lower than 5, the assemblage biomass increased with increasing species richness; when the species number was higher than 5, there were no obvious relationships between assemblage biomass and species richness. A stronger complementary effect was observed inside the assemblage, presenting a hump-shaped variation with increasing species richness. The sampling effect of the assemblages occurred at stable growth phase.

Ammonia-oxidizing archaea and their important roles in nitrogen biogeochemical cycling: A review.

2010, 21(08):  2154-2160. 

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As the first step of nitrification, ammonia oxidation is the key process in global nitrogen biogeochemical cycling. So far, the autotrophic ammonia-oxidizing bacteria (AOB) in the β- and γ -subgroups of proteobacteria have been considered as the most important contributors to ammonia oxidation, but the recent researches indicated that ammonia-oxidizing archaea (AOA) are widely distributed in various kinds of ecosystems and quantitatively predominant, playing important roles in the global nitrogen biogeochemical cycling. This paper reviewed the morphological, physiological, and ecological characteristics and the molecular phylogenies of AOA, and compared and analyzed the differences and similarities of the ammonia monooxygenase (AMO) and its encoding genes between AOA and AOB. In addition, the potential significant roles of AOA in nitrogen biogeochemical cycling in aquatic and terrestrial ecosystems were summarized, and the future research directions of AOA in applied ecology and environmental protection were put forward.

Effects of elevated atmospheric CO₂ on paddy soil nitrogen content during rice season.

2010, 21(08):  2161-2165. 

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Taking the China rice/wheat FACE (Free-Air Carbon Dioxide Enrichment) as a platform, this paper studied the effects of elevated CO₂ on the NH₄⁺-N and NO₃^--N contents at different depths of paddy soil in rice season. Under elevated CO₂, the NH₄⁺-N content in plough layer increased at early growth stage but decreased at late growth stage, and the soil NO₃^--N content at the depths 5, 15, 30, 60, and 90 cm increased by 46.5%, 36.8%, 23.3%, 103.7%, and 42.7%, respectively, with a significant increase occurred at the depths 60 cm (P<0.01) and 90 cm (P<0.05), compared with the control.

Control effect of parasitic Metaphycus parasaissetiae on host Parasaissetia nigra.

2010, 21(08):  2166-2170. 

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A laboratory test was conducted to study the control effect of parasiticMetaphycus parasaissetiae on its hostParasaissetia nigra. The functional reactions of the parasitism conformed to the Holling Type Ⅱ Equation, but the parameters of the functional reactions varied with temperature. Taking the ratio of instant attack rate to preying time (a/T_h) as an evaluation index, the preying efficiency at 30 ℃ was the highest, with a/T_h being 23.4211. There was a stronger interference effect in the functional reactions of the parasitism within M. parasaissetiae populations. With the increase of the population density, the amounts of parasitism decreased gradually. Hassell Equation (E=QP^-m) could describe the relationships between the searching efficiency of M. parasaissetiae and its population density much precisely within the range of 21 ℃-33 ℃. The interference increased with temperature within the range of 21 ℃-27 ℃, and the interference coefficient reached the highest (0.6626) at 27 ℃. When the temperature was raised to 30 and 33 ℃, the interference coefficient decreased to 0.6161 and 0.5916, respectively. In the prophase of egg-laying, the parasitized P. nigra could be entirely controlled by M. parasaissetiae. However, when a few larvae were crawling out, the control effect was declined to 81.4%.