Table of Content

25 January 1997, Volume 8 Issue 1

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Articles

Internal and external nutrient transfers in foliage of some north deciduous trees Ⅰ Changes of nutrient concentrations and contents

Xu Fuyu, Wang Lihua, Li Peizi, Xu Siming, Zhang Songyun

1997, 8(1):  1-6. 

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Twelve north deciduous tree species are studied to characterize their changes of dry leaf weight, and concentrations and contents of ash, organic matter and 7 elements in leaves per area before and after leaf fallen.Different change patterns are detected among tree species and among elements.The decrease of dry weight and organic matter in fallen leaves is measured in all analyzed tree species, while the increase is found in ash concentrations of all speies and in its contents of most species (except Robinia pseudoacacia,Elaeagnus angustifolia and Juglans madshurica). The contents of N, Pand Kare decreased by about 1/3 to 2/3 during leaf fallen.Mg contents are decreased in species Elaeagnus angustifolia, Juglans mandshurica, Ulmus propingua, Quercus mongolica and Larix kaempferi, but increased in others. Fe content is higher in fallen leaves than in living leaves for all trees except Elaeagnus angustifolia. Ca and Si concentrations and their contents are markedly increased in all species.

Photosynthesis light response characteristics of subtropical tree species seedlings under different irradiances

Liang Chun, Lin Zhifang, Kong Guohui

1997, 8(1):  7-11. 

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Potted seedlings of Pinus massoniana, Schima superba, Castanopsis fissa and Cryptocarya concinna, the dominant tree species in Dinghushan subtropical forests, are grown under 100%,40% and 16% of natural illumination for one year, and their photosynthesis light response curves are determined with O₂ electrode under a series of light intensity from 0 to 2500 μmol quanta m^-2·s^-1. The comparison of dark respiration rate (DRR), maximum net photosynthetic rate (Amax), quantum use efficiency (QUE), light compensation point (LCP), light saturation point (LSP) and photo inhibition point (PP) for the seedlings of these tree species under different irradiances shows that Cryptocarya concinna is shade tolerant and has a limited photosynthetic potential of acclimating high PFD. The Amax of its seedlings growing under 100% sunlight is about 58% of those growing under heavy shade (16% sunliht). Pinus massoniana, Schima superba and Castanopsis fissa are sun loving species with higher DRR, Amax, LCP, LSPand PP. For Pinus massoniana, its photosynthetic potential of acclimating low PFDis limited, while Schima superba and Castanopsis fissa show a relatively high photosynthetic potential of acclimating high and low PFD. The relationship between photosynthetic physiological characters of tree species and their succession status is also discussed.

Effect of elevated CO₂ concentration on leaf water regime of subtropical tree seedlings

Wei Caimiao, Kong Guohui, Lin Zhifang

1997, 8(1):  12-16. 

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Potted seedlings of Castanopsis fissa and Schima superba, two dominant species in monsoon evergreen broad leaf forest of Dinghushan, Guangdong Province, are grown in semi opened chambers with ambient(340 μl·L^-1) and elevatcd (500±50 μl·L^-1) CO₂ concentration under natural light for three months.The stomatal conductance of leaves grown in high CO₂ is decreased by 13% for C.fissa and by 18% for S.superba,and their transpiration rate is decreased by 20% and 18%, respectively. For these two species, their water use efficiency is increased by more than 100%. The diurnal courses of stomatal conductance and transpiration rate are quite different between plants grown in elevated and ambient CO₂. When all plants are put back to ambient CO₂ without chamber, no obvious difference of stomatal conductance and transpiration rate is observed on the seventh day.

Influence of photoperiodic condition on temperature effect level of Photoperiodic Sensitive Genie Male sterile (PGMS) rice

Xue Guangxing, Shen Yuezheng

1997, 8(1):  17-20. 

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Controlled temperature and photoperiod experiments with two day/night temperature (31/22℃,27/22℃) and 6 photoperiods (10.0,12.0,13.0,13.6,14.0 and 15.0 hours)were conducted in a phytotron to observe the influence of photoperiodic treatments on temperature effect level of 3 varieties of PGMS rice. The results indicate that under the temperature regime the male fertility of controlled variety is completely normal, but the conversion between SD-fertility and LD-complete sterility can occur in PGMS rice, a drop of 4℃ in temperature can lead to their temperature effect, and result in a significant decrease of their male sterile degree under different photoperiods. The temperature effect level varies significantly with different photoperiods, which increases abruptly with the shortening of day length, and tends to negatively correlated with day length. It is implied that by means of breeding PGMS rice with shorter sterile critical day length and artificially regulating the relationship between practical day length and sterile critical day length,it is possible to reduce the influence of temperature and to stabilize the male sterile level of PGMS rice.

Radiation interception by erectophile maize colony

Zhou Yunhua, Xiang Yueqin, Lin Zhonghui

1997, 8(1):  21-25. 

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Measurement on the reflectance, transmissivity and interception of total solar radiation(TSR) and photosynthetic active radiation (PAR) of erectophile maize colony (variety Yedan 13) show that the maize has the characteristics of transmission and interception in erectophile leaves. The extinction coefficient of TSR and PAR before tasseling are 0.284 and 0.401 respectively. The nature of higher transmission of erectophile maize colony implies that the planting density of this type can be higher than that of planophile type. The transmissivity of tassel of the colony is about 75%. The illumination condition of the foliage can be improved in a certain degree by cutting some tassel of plants. The relationships between mean daily interception, ā_Q and ā_U,of TSR and PAR and the green leaf area index (L)are discussed respectively.

Soil improvement effect of different management models on low hills in the lower and middle reaches of Yangtze River

Yu Fengan, Peng Zhenhua, Jiang Zehui

1997, 8(1):  26-30. 

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The investigation on different integrated management models in four experimental sites in the lower and middle reaches of Yangtze River shows that after integrated management, the plant coverage percentage is increased, soil erosion and soil bulk density are decreased, soil water content is increased, and the contents of organic matter and N, P and K are substantially improved.

Optimized model of agro-animal husbandry for black soil region of Songnen Plain and its implementation effect

Wang Zhanzhe, Han Bingjin, Xia Enjun, Gao Bing

1997, 8(1):  31-36. 

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A 5 years study on the optimized model of agro animal husbandry for black soil region of Songnen Plain show that after implementing this model on the same area of farmland and with relatively stable cost, the total biological production (protein) of agriculture and animal husbandry, productivity of energy input, utilization rate of solar energy, and net income are 7.911× 10⁵ kg, 1.43, 0.40% and 3.2568×10⁶ RMB,increased by 68.4, 16.3, 48.2 and 75.5%, respectively.

Farmecosystem diversity in typical agricultural regions of China

Xu Jianming, Wen Dazhong, Luo Liangguo, Luo Qishi

1997, 8(1):  37-42. 

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Through detailed investigation of farmecosystem diversity in five typical agricultural regions of China, the database of farmecosystem diversity is established. After analysing the characteristics of land use, crop sequence, crop arrangement and distribution of system's units in these regions, the index of each region's farmecosystem diversity is calculated. The results show that the maximum richness of these farmecosystems is quite low and their difference is not significant; the difference among the average richness (Ta) of each region is obvious, and in general, the Ta is higher in hilly areas than in plain areas, but that in plain areas has a trend to decline from south to north.Little difference of enenness (E) and dominance (D) can be found among these farmecosystems, but Eis higher in hilly areas than in plain areas, and D is adverse to E. In accordance with the current situation, some suggestions for constructing diversified farmecosystem structure and for improving farmecosystem diversity are given.

Mathematical model of water-yield potential of dryland crops on South Loess Plateau and its parameters revision

Li Kaiyuan, Li Yushan

1997, 8(1):  43-48. 

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Amathematical model for calculating the water-yield potential of dryland crops is established, and its main parameters are revised.The methods for calculating crop water consumption and water revision coefficient are also put forward. Based on the calculation, the water yield potential of winter wheat is 5300～6300 kg·hm^-2 and that of spring maize is 7700～9000 kg·hm^-2.In addition, the water condition of dryland is evaluated, which indicates that the east region of south loess plateau has a worse water condition and a greater yield increase potential through irrigation.

Soil NO₃^--N transport under field unsaturated flow condition——a simulation study

Cui Jianbo, Zhuang Jiping

1997, 8(1):  49-54. 

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Based on the theory of Markov Process, a stochastic model is established to simulate the interlayer transport of NO₃^--N in a cinnamon soil with unsaturated water flow. This model converts the temporally variable system into a system closely resembles the time homogeneous case, and makes Markov Process model applicable. The probability distribution of NO₃^--N is given for each soil layer under a given soil water flow and a given transport intensity of source and sink. In calculating the transport probability from one soil layer to another one, the main processes of NO₃^--N uptake and its leaching, nitrification and denitrification are considered, and the relationship between N transformations is calibrated with correlation function. Amicro plot experiment on NO₃^--N transport is installed to verify the results obtained from simulation study, which shows a satisfactory agreement between measured and simulated results, indicading that the model can be used in similar areas to predict and evaluate the behavior of NO₃^--N transport in soil crop system.

Effect of long term foliage dressing rare earth elements (REEs) on their distribution, accumulation and translocation in soil spring wheat system

Liu Shujuan, Wang Lijun, Zhang Shen

1997, 8(1):  55-58. 

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In this paper, the distribution,accumulation and translocation of rare earth elements(REEs) in soil and spring wheat are studied after foliage dressing with REEs for 12 years. The long term foliage dressing with REEs did not result in the accumulation of REEs in upper and lower soil layers. At maturing stage of spring wheat,the REEs content is in the order of root>leaf>stem and crust. Comparing with control, foliage dressing leads a higher accumulation of REEs in root, but no significant difference is found in stem and crust between these two treatments. The distribution patterns of REEs in root,stem,leaf and crust are similar to that in soil. Long term foliage dressing with REEs did not have an obvious effect on the REEs content of spring wheat grain.

Dynamics of organic material decomposition and soil respiration in intensive and high yield agroecosystem

Cui Yuting, Han Chunru, Lu Jindeng

1997, 8(1):  59-64. 

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In this paper, mesh-bag method is used to study the decomposition of straws and roots of maize and wheat, and isolated pot alkaline liquid assimilation method is used to determine soil respiration. Based on these, the yearly mineralization rate and balance coefficient of soil organic carbon are calculated. The decomposition dynamics of organic materials doesn't show any difference between middle and high yield fields, but the soil respiration rate of these two fields are 1725.7 and 1878.5 g CO₂·m^-2·yr^-1,respectively. The yearly mineralization rates of soil organic carbon are 5.48 and 5.64%, and the balance coefficients are 1.86 and 1.84 respectively. The results suggest that intensive management of crop field doesn't decrease the content of soil organic carbon.

Numeral, temporal and spatial patterns of animal and entomogenous fungus communities in Masson pine stands with reasonable chemical control

Han Baoyu, Li Zengzhi, Wang Chengshu, Cui Lin

1997, 8(1):  65-69. 

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Investigations on animal and entomogenous fungus in pure Masson pine stands show that the species numbers of phytophagous, predatory, parasitic and spider groups are 51, 12, 7 and 26%, respectively. The ratio of beneficial to harmful organism individuals is about 1∶10. Within 2 similar stands or layers, the family and species numbers are equal to or close to each other. Their dominant orders are similar. The fluctuations of species or individual numbers of phytophagcus, predatory, parasitic and spider groups are almost the same within the stands and layers. Principal component analysis indicates that in1 anniversary year, the community is in a state of circulating succession of "preparing overwintering inlate autumn→hibernation→resuscitation in early spring→flourishing during spring, summer and early autumn". The stability and the self adjusting potential of the community are quite strong.

Ecology of soil animal community in vegetable plots of suburbs along the Yangtze River in Anhui Province

Lu Youcheng, Wang Zongying, Luo Aiwu, Chen Fayang

1997, 8(1):  70-76. 

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In this paper, the soil animal community in vegetable plots along the Yangtze River is studied. 18222 specimens belonged to 6 phyla, 14 classes, 29 orders and 72 families are collected, among which, collembola, acarina and nematoda are dominant. In same plots, soil animal community has the maximum compositional richness, diversity and evenness index in July and the minimum ones in December, and its individual number, density and superiority index are the maximum in January. In August, the Svalue of Brassica chinensis and Allium tuberosum plots is the maximum, the second is Vigna sequipedalis and Clycine max plots, the minimum is Raphanus sativus plot. The structure of soil animal community is varied with the growth period of different varities of vegetables. Black sandy soil with high fertility level has a higher value of each index of soil animal community than sandbar.

Density dependence of Phalaris aruandinacea clonal population on middle mountain region of subtropical zone of China

Yang Yunfei, Fu Linqian

1997, 8(1):  77-82. 

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The quantitative analysis on the density dependence of Phalaris arundinacea clonal population on middle mountain regions of subtropical zone of China shows that mean tiller weight, mean weight of leaves per tiller and mean stem weight per tiller are decreased in power function with the increase of population density at different growing stages. At flowering stage, the reproductive development is restricted by the population density, and the vegetative growth not only by the tiller density, but also strongly by the population density. The death rate of population is negatively correlated with its density at different growing stages.

Influence of light intensity on differentiation and growth of Leymus chinensis clone

Yang Chi, Yang Li

1997, 8(1):  83-87. 

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Under conditions of 60,45 and 30% shading, the characters of growth and differentiation of Leymus chinensis clone are studied in greehouse. The results show that low light intensity reduces the biomass accumulation of plant, restrains the growth and differentiation of clone, and decreases the total number of rhizomes and ramets. There exists a significant difference of the length and node number of rhizome and the dry biomass of clone under different light intensities, which is more obvious in spring.

Domestic wastewater treatment with means of soilless cultivated plants

Li Fangbai, Wu Qitang

1997, 8(1):  88-92. 

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The study on the domestic wastewater treatnent with soilless cultivated Canna generalis, Iponoea aauatica, Oruza sativa and O.meyeriana subsp.granulata shows that in static experiment, the average removal rate of COD and total N and P is respectively 8.7 ～19.8, 20.3～66.6 and 23.5～67.1% higher than control. The removal capacity of these plants is in the order of Canna generalis and Iponoea aquatica > Oryza sativa > O.meyeriana subsp granulata. In third grade plant lagoon system, the removal rate of BOD₅,COD and total N and P is respectively 79.7, 71.1, 66.5 and 60.7%; but in artificial rapid infiltration soil and plant lagoon system, it is 83.9, 79.3, 64.8 and 40.9% respectively.

Accumulation and dynamic change of polycyclic aromatic hydrocarbons(PAHs)in wastewater irrigated soils

Song Yufang, Chang Shijun, Li Li, Ma Xuejun, Sun Tieheng

1997, 8(1):  93-98. 

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The analysis of 14 polycyclic aromatic hydrocarbons(PAHs)in wastewater irrigated soils shows that in general,soils at up stream of irrigation channel have highest accumulation of PAHs,the second is the soils at the mid stream,and those at the down stream are similar with control.But in Shenfu area irrigated with petroleum wastewater,the accumulation of PAHs is found in all soils at up ,mid and down streams of irrigation channel.Application of wastewater during rice growing season can increase the total amount of PAHs in soil,the trend of increase or decrease of each pollutant is different.

Water ecological criteria of NaSCN

Zhang Tong, Jin Hongjun

1997, 8(1):  99-103. 

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Based on the features of aquatic biota in China and toxicity test with aquatic organisms, the water ecological criteria of NaSCN, one important pollutant in acrylonitrile acrylic wastewater, are formulated. It is suggested that the criteria continuous concentration (CCC) and criteria maximum concentration (CMC) are 0.2530 and 1.350 mg·L^-1, respectively.

New approaches in researches of water use efficiency in semi arid area of Loess Plateau

Li Fengmin, Zhao Songling

1997, 8(1):  104-109. 

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Based on the background of agricultural conditions, especially the soil water characters in semi arid area of Loess Plateau, and on combining with the progress in field of root to shoot communication, the research and developmental potential of root chemical signals were discussed in this paper. The core of water saving agriculture in this area is to increase crop's water use efficiency (WUE). The ways for increasing WUE should be included: 1)decreasing inefficient evaporation from soil surface, and 2)increasing roots in deep soil, decreasing those in top soil, optimizing resource allocation pattern, and increasing reproductive allocation proportion. Root chemical signals affect strongly all the two aspects. According to the present accumulation of knowledge, the study on effects of root chemical signal on crop productivity can reveal some important theoretical problems.

Effect of seed soaking with Hg on enzyme activities of maize seed during its germination

Ma Chengcang, Hong Fashui, Li Qingfang

1997, 8(1):  110-112. 

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The study shows that seed soaking with HgCl₂ can decrease the germination rate of maize, inhibit the growth and respiration intensity of its seedling, and the activities of aminotransferase, diastase and lipase in endosperm and those of diastase and lipase in seedling during the process of germination. Low concentration of HgCl₂ can promote maize growth.