Table of Content

10 February 1994, Volume 13 Issue 01

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Effects of Plastic Sheet Mulcbing on the Ecological Environment in Late Wheat Fields

SunBenpu, Li Xiuyun, Zhang Baomin

1994, (1):  1-8. 

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lastic sheet mulching could coordinate water,nutrient,air and heat in soil,which creats a good ecological environment for winter wheat growth and development.The mulch has significantly raised the temperature under the film.The decreased accumulated temperature by late sowing was compensated by increased accumulated temperature,and winter wheat was proceeded through their vernalization stage to photostage;at the some time,the spikelet differentiation periods were prolonged.This is the basic reason for the higher yield of wheat under plastic sheet mulching than cultivated without film covering.

Population Dynamics of Citrus Rcd Mite(Panonychus citri McG.)and Its Natural Enemies in Xianning Area

Gan Zhongyi, Wang Shengtao

1994, (1):  9-12,20. 

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Because of the stable ecological environment in the orange garden,the population develop- ments of Citrus red mite and its enemies coincide with Leslie Pattern:H(t+1)=5.019224H(t)/[1+49. 525954P(t)],p(t+1)=2.681411P(t)/[1+3.651781P(t)/H(t)]. Analysis of the populational dynamics shows that:(1)controlling effect of natural enemies(Stethorus punctillum,etc.)on Citrus red mites is usually enlarged with the mite's population rising in the orchard.If the density of the mite's enemies amounts to 0.05-0.08 head per leaf,development of the injurious mite can be controlled.(2)The ratio between beneficial and injurious insects,which is changing with their populatlonal densities,restricts the populational trends of the mite's enemies,so the ratio cannot be simply used as an index to control the injurious mites.(3) Extraordinarily low population of the mite is not beneficial to the development of its enemies.Spraying pesticide too early or too much may lead to great damage from the mite,and unsuitable pesticide using will bring about the same result.

Estimation of Ecological Effect and Economic Benefit of Artificial Tea-Fruit Community

Wei Guoxiong

1994, (1):  13-16. 

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According to the experiment on artificial community of tea-fruit plants,the community is advantageous for the improvement of soil fertility and micro-environment of tea plantation;for the increased resistance to adverse circumstances and the yield and quality of tea.The intercropping of tea and fruit plant is advantageous both ecologically and economically.

Ways of Utilizing Tropical Secondary Forest and Soil Microbial Activity

Xu Lianfeng, Zhu Wukun

1994, (1):  17-20. 

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Researches on the influence of different felling intensity and different ways to exploit and utilize tropical secondary forest in Hainan Island on soil microbial activity showed that the total quantity of soil microorganism and activity of soil enzyrnes gradually drop down as the felling intensity rise.All activity indexes are lowest in the treatment of clear felling and are significantly higher in rubber plantation than in slash-and-burn cultivation.It ls suggested that 50% exploitation and strip cropping of rubber would be the reasonable utilization ways if only soil microbial activity are considered.

Studies on the Litterfall of Two Forest Typcs in Mid-Altitude of Laoshan Mountain in Tianlin County

Liang Hongwen

1994, (1):  21-26. 

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The production,nutrient element content and decomposition rates of litterfall of two forests were studied in mid-altitude of Laoshan mountain,Tianlin county,Guangxi.The results indicate:1.The mean annual litterfall in evergreen-deciduous broad-leaved mixed forest and pure Chinese fir plantation are 5.153 and 5.176t.ha^-1 respectively,and total amount of eight nutrient elements for the former is 159.82kg(ha穣r )^-1,in which N 80.54,P 3.89,K 14.77,Ca 40.47,Mg 15.86 ,Mn 3.96,Cu 0.06 and Zn 0.27kg(ha.yr)^-1;for the latter they are 118.84,39.44,2.02.7.65,54.80.11.68,3.08,0.06 and 0. 11 kg(ha穣r )^-1,indicating the litterfalls belong to N-rich type and Ca-rich type respectively for the two forests.2.The rate of weight loss after 376 days on the forest floor is 44.50% for broad leaves,and 33.03% for needles.The exponential decay model is used and the annual decay rate of leaf litter is estimated to be 0.5978g(g穣r)^-1 for broadleaves,and 0.4025g(g穣r)^-1 for needles.showing that the decomposition of broadleaves is farster than that of needles.

Research on Microclimatic Characteristic in Plantation of Rubber Intercropped witb Amomum longiligulare

Zhou Zaizhi, Zheng Haishui, Yang Chengjiang, Yin Guangtian

1994, (1):  27-31. 

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Microclimatic factors including light intensity,temperature and relative humidity and so on were measured in spring in plantation of rubber intercropped with Amomum longiligulare,pure rubber plantation and bare land in Nanhua State Farm of Guangdong province, The results showed that light intensity at 0.2m and 1.5m above the floor was 56% and 41% lower in the intercropped plantation than in pure rubber plantation;the average,the highest and the lowest temperatures of the floor were 2.3,4.9,1.4℃ lower;and soil temperature at 5,10,15,20cm depthes of the floor were 2.1,1.2,1.1,0.9℃lower respectively;air relative humidity was 6.3% higher.The ecological environrnent in intercropped rubber plantation was improved.

Advancement of Tbeoretical Research in Ecotone

Gao Hongwen

1994, (1):  32-38. 

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The historical development of Ecotone theory and the latest development of expanded ecotone theory since the mid-1980s were reviewed and discussed detailly in this paper.

Spatial Distribution Patterns of Rodents

Fang Jiming

1994, (1):  39-44,68. 

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Spatial pattern is one of the most important ecological properties of species,Unlike studies of birds and insects,the studies on spatial patterns of rodents have not been well documented in the past.This paper showed that the studies on spatial pattern of rodents was developed from qualitative to quantitative.They were in close relationship with home range,behaviour and reproduction.There were differences between males and females,and between juveniles and adults.Some species revealed seasonal changes of spatial patterns,some not.The analytical and statistical methods for spatial patterns were also listed in accordance with specific conditions.

Factors Influeucing the Digestive Enzyme Activity of Copepods

Tang Hong, Li Shaoching

1994, (1):  45-50. 

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Factors influencing the digestive enzyme activity of copepods are as follows:(1) Food conditions:Both seasonal changes in food supply in natural sea area and changes of prey species and diet concentrations during experimental feeding affect the digestive enzyme activity of copepods. Their relationship fits the"Assimilation Law",( 2 )There exists a positive relationship between digestive enzyme activity of copepods and their energy requirements at various growth stages.(3) Diurnal vertical migration of animals may influence their diurnal periodicity of digestive enzyme activity.(4)Copepod's"internal clock",which resembles the neuroendocrine system of higher crustaceans,may control its digestive enzyme activity,(5)Other factors such as physical and chemical factors(e.g.temperature,pH,lisht,etc.),time factors etc.

Allelopathic Effects and Preliminary Isolation of Root Exudates of Wedelia chinensis(Osb.)Merr

Zeng Rensen, Ling Xianglian, Tan Huifen, Zeng Qiang

1994, (1):  51-56. 

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Chinese Wedelia(Wedelia chinensis(Osb.)Merr.),a common garden herb species in South china,tends to form a pure community. Its root exudates collected by sand culture shows allelopathic effects on seedling growth of turnip(Raphanus sativus),rice(Oryza sativa).cucumber(Cucumis sativus)and mungbean(Phaseolus aureus).Theinhibitory concentrations of exudates vvere determined.The hydrophobic root exudates of W.chinensis,obsorbed by XAD-4 resin in hydroponic culture system,shows allelopathic effects on the seedling growth of barnyardgrass(Echinoloa crusgalli),lettuce(Laotuca sativa)nd trunip.By means of extraction using petroleum ether, chloroform and methanol,the exudates are separated into three portions:Ra(5.9%),Rb(74.5%)and Rc(19.6%).Rb,most inhibitory porticn,was isolated into 8 fractions by means of preparatory thin layer chromatography Fraction 1 and 32 were most inhibitory.

Influence of Ecoenvironment on the Yield and Quality of Ligusticum chuanxiong Hort

Ding Derong, Chen Xingfu, Lu Jin, Huang Wenxiu, Liu Suirong

1994, (1):  57-59. 

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From the results of this study,ecological environment exerts strong influence on the yield and quality of Ligusticum chuanxiong Hort.With the variation of ecoenvironment, its yield,shape and quality alter,Ligusticum chuanxiong Hort.is suitable to alluvial soils of about 700m above sea level,with 15.2℃ annual mean air temperature,16.8℃ soil temperature,1257mm annual mean precipitation and 1035h annual mean solar radiation.

Computer Processing of PV Curve Analysis and Its Application in the Research of Woody Plant-Water Relations

Liu Jiangwei, Liu Yarong, Wang Shiji

1994, (1):  60-63. 

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Based on the mathematic formularization of PVcurve,it's shown that PV curve is linear whenpressure p=0.and nonlinear when p>0.At the same time,the new analysis by computer(Schulter,1988)was introduced and applied to Populus simonii data processing.The results show that at the saturated state leaf osmotic potential is 1.0512MPa,elastic modulus 1.7MPa;and at the turgor loss point,the relative water content(RWC),osmotic potential and elastic modulus are 83.5%, 1.3478MPa and 0.17MPa ,respectively,In the analysis modification,the statistic probability is 0.01 and R²reaches to 0.991. In addition,six kinds of figures of PV curves explain in detail the water relation of this woody plant.

Analysis of Agro-Ecolomic System From the Viewpoints of Holograpby

Cao Zhiping

1994, (1):  64-68. 

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Agro-ecolomic system was analyzed from the viewpoints of holographic relationship between ecosystem and organism,and the following common characters in eight aspects between agricultural production process and material metabolism were found:1.Substantial,2.Key node,3.Substitution or conversion,4.Targets,5.Two kinds of forms,6.Management or catalysis,7.Non-balanced process,8.Energy storage.The realistic significance of the analogical analysis was also discussed and some new concepts were put forward about the criteria system and calculating methods for assessing the ecolomic benefits

Studies on Crop Growth Modelling and Its Application

Yu Zhenrong

1994, (1):  69-73. 

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Research advances in crop growth modelling and its application are reviewed in this paper.A list of published materials on crop growth simulation models is presented. The crop growth modelling is applied in two major fields:(1)to better understanding of the processes involved in crop production;and(2)to solve problems,such as evaluation of crop productivity,computer aided decision making for crop production.