Table of Content

25 November 1997, Volume 8 Issue 6

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Articles

Cold-resistance ability of two mangrove species Kandelia candel and Aegiceras corniculatum during their overwintering period

Yang Shengchang, Lin Peng

1997, 8(6):  561-565. 

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In this paper, the leaf cold resistance ability of two mangrove species Kandelia candel and Aegiceras corniculatum growing on Jiulongjiang Estuary of Fujian Province was measured by conductivity method, and the relationship of this ability with the contents of leaf water, chlorophyll and soluble protein and the activity of peroxidase during overwintering period was studied. The results show that the cold resistance ability of these two mangrove species from September 1988 to April 1989 is increased with decreasing of air temperature, and reached their maximums in January and December, respectively.Their half lethal temperature is respectively -9.3 and -9.0℃.After winter, the cold resistance ability is decreased dramatically with the rise of air temperature. The increase of the cold resistance ability is related with the increase of bound water or the decrease of free water content in leaf. Both the soluble protein content and the peroxidase activity have a similar variation trend to the cold resistance ability. The ratio of leaf bound water to free water and the ratio of leaf chlorophyll a to chlorophyll b may reflect the cold resistance ability of these two mangrove species: the higher the both are, the stronger the cold resistance ability is.

Physioecological study on highyielding cultivation of rice by dryraising seedling and thinspacing transplanting techniques Ⅰ. Quality and ecophysiological characteristics of rice seedlings grown on dryfertile nursery

Lin Wenxiong, Wan Songliang, Lian Yiyuan, Guo Yuchun, He Shuilin

1997, 8(6):  566-570. 

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The study shows that in comparison with wetraising nursery,dryraising nursery had a greater size of soil aerobic azotobacter,cellulose decomposer,ammonifier,organic phosphorus decomposer and nitrite bacteria and a higher activity of soil protease,cellulase,phosphatase,urease and invertase,which is favorable to the conversion of soil matter and energy and the promotion of soil nutrient availability. It also shows that on dryraising nursery,rice seedlings had a more develped root system with a stronger ability of oxidation,and the roots exhibited a higher activity of amylase,nitrate reductase,ATPase and cell protective enzymes such as peroxidase,catalase and superoxide dismutase.

Vegetative propagation characters of clonal populations of Hierochloe glabra in Songnen Plain

Yang Yunfei, Li Jiandong, Zheng Huiying

1997, 8(6):  571-574. 

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Hierochloe glabra is a typical clonal grass.Its tiller nodes can propagate two generations.The tiller nodes can survive at most for three years,and the rhizomes for two years.There are two age classes in both tiller and rhizome populations,and the first age class constitutes the majority.The potential clonal populations consist of winterness seedlings of tiller and rhizome buds. It is estimated by the numbers of the potential clonal population that the grass would keep its existing positions and roles in the mixed communities of hay making plots,and would enhance itself as a dominant species in the communities of grazing plots.

Effect of water supply from deep soil on dry matter production of winter wheat

Li Fengmin, Guo Anhong, Luo Mei, Zhao Songling

1997, 8(6):  575-579. 

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Aroot growth device was used to study the effect of water supply from deep soil on dry matter production of winter wheat. The results show that soil with high moisture in deeper layer and low moisture in upper layer (treatment LH) still maintains a higher water content both in soil and in plant leaf during the milking stage of wheat growth. This treatment gives the highest dry weight of roots, flag leaves and spikes, and hence, a maximum yield potential. It seems that such a soil moisture status is beneficial to promoting root development in deeper soil, balancing water utilization, and improving crop yield.

Horizontal transfer of plasmid pLV1016 among Rhizobium fredii strains in soil

Cui Mingxue, Zhang Chenggang, Li Mingqi, Jin Suying

1997, 8(6):  580-584. 

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Broadhost range conjugative plasmid transfer between R.fredii QB1131 (pLV1016) and lux3 or between QB1131(pLV1016) and indigenous bacteria on filter,in broth,and in microcosms containing sterile or nonsterile soil,planted with or without soybean were studied. The donors,recipients and transconjugants were enumerated on selective media 1 day after inoculation,and the growth rates of donor and recipient as well as the transfer rate constants (γ) of plasmid were calculated for three initial parental densities in each system.At the same initial density, γ value was the highest in filter mating and the lowest in soil microcosm mating,which was not influenced by soybean spermosphere or by soil sterilization or nonsterilization.But in microcosm experiments,it was inversely related to initial parental density and directly related to donor growth rates.In nonsterile soil,plasmid pLV1016 could transfer from R.fredii to indigenous bacteria Rhizobium sp.or Pseudomonas sp.

Effect of Ce accumulation on soil microflora in yellow cinnamon soil

Tang Xinyun, Zhang Zili, Cheng Yong, Wan Haifeng, Zhu Weimin

1997, 8(6):  585-588. 

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Different accumulations of Ce due to a longterm application of rare earth elements were simulated in yellow cinnamon soil to study the ecological effect of rare earth on soil microflora. The sensitivity of different groups of soil microbes to Ce is decreased in the order of bacteria>actinomycetes>fungi. The amount of bacteria is inhibited when the concentration of Ce is larger than 10% of adsorption capacity (AD), and the growth of actinomycetes was stimulated at its concentration of <10% AD. Ce concentration ranged in 5～50% AD had a strong stimulation on the amount of soil fungi, and that of >5% AD inhibited aerobic cellulolytic bacteria and ammonifying bacteria. Ce accumulations of 5～10% AD and 5～50% AD stimulated the amounts of cellulolytic and proteolytic fungi, respectively. Under the stress of high accumulation of Ce, the population structures of actinomycetes, fungi, cellulolytic fungi and ammonifying microbes were changed in different degrees.

Methane oxidation in paddy soil

Yan Xiaoyuan, Cai Zucong

1997, 8(6):  589-594. 

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The laboratory study on methane oxidation in paddy soil shows that soil sample collected before earlyrice transplanting can not oxidize atmospheric methane, but can oxidize the supplied methane quickly when its concetration is higher than 10μl·L^-1. The oxidation rate of methane is increased with its initial concentration. After preincubated under high concentration of methane(>1000 μl·L^-1) for 10 days, the soil which can not oxidize atmospheric methane begins to oxidize it. The study also shows that paddy soil with a high methane emission flux has a high potential of methane oxidation.

Studies on nodulation and efficiency of S.fredii using GUS gene

Meng Songdong, Zhang Zhongze

1997, 8(6):  595-598. 

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In this study, GUS gene was transfered into the donor strain S.fredii 8855 using GUS (β-glucuronidase) gene marking technique . Nodules occupied by the marked strain turned blue in the GUSstaining buff, while others occupied by the indigenous rhizobia didn't. The effects of indigenous rhizobia on inoculation could be valuated by the technique easily. Greenhouse experiments showed that the ability of acid and alkaline resistance of S.fredii 8855 was higher than that of the indigenous rhizobia, and it could migrate in large scale in the soil. Inoculation significantly increased the yield of soybean when the nodule occupancy was no less than 43%. The yield was positively related to the nodule occupancy (r=0.98), but unrelated to the total nodule number (r=0.13). Nodulation was inhibited by soil Nand promoted by Papplication.

Spatial dynamics of vegetable aphid population in suburbs of Hangzhou

Wang Xingeng, Liu Shusheng, Wu Xiaojing, Zhang Guangmei, Gong Hongfei

1997, 8(6):  599-604. 

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Systematic investigations on vegetable aphid population were carried out on 10 crops of Brassica oleracea var.capitata and 23 crops of B.campestris ssp.chinensis during 1990～1992 in the suburbs of Hangzhou.The K value of negative binomial distribution less affected by density was chosen to describe the spatial and temporal patterns of mixed aphid population. The results indicated that the mixed population of Myzus persicae and ipaphis erysimi was aggregated on the two vegetables throughout the year, but the aggregation intensity changed seasonally. The population was highly aggregated from July to September, and two peaks of dispersal was shown on May and November. The intensity of aggregation on Brassica oleracea var. capitata differed between seasons. From spring to summer, the population changed from highly to loosely aggregated, and then, to highly aggregated again, but from summer to autumn, the aggregation intensity was always very high. The temporal pattern of aggregation from autumn to winter differed between years, and the intensity of aggregation increased gradually, and then, fluctuated from winter to spring.The aggregation intensity of L.erysimi was higher than that of M.persicae. With reference to the trade-off of population and the change of environmental factors, the mechanism of the observed spatial patterns was discussed.

Trophic niche and interspecific food competitive model of grasshoppers in desert grassland

He Dahan, Zheng Zhemin

1997, 8(6):  605-611. 

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The trophic niche and interspecific food competitive model of 12 grasshopper species in Ningxia desert grassland were studied.Microscopic examination of crop contents was used to analyze the food preference and food utilization menu to determine the overlap and breadths of trophic niches among these grasshopper species.On the basis of the differentiation characteristics of ecological niches,the 12 grasshopper species were divided into 4 trophic demanded groups:forbivorous,mixed forbivorous,mixed graminivorous,and mixotrophicus species.Anew model to evaluate the interspecific food competition was proposed by combining feeding frequency,biomass and population density of grasshopper,and the interspecific food competitive interactions among 12 grasshopper species were discussed.

Geostatistic analysis of spatial pattern of Dendrolimus punctatus

Shi Gensheng, Li Dianmo

1997, 8(6):  612-616. 

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Geostatistic analysis of the spatial patterns of the overwintering generation pupae, first generation egg masses and early stage larvae of Dendrolimus punctatus (massonpine caterpillar) in Pinus elliottii-P.massoniana-P.taeda forest indicated that the semivariograms of pupae was fitted to the spherical curves at 0°,45°,90°and 135°directions, and the spatial continuity was the strongest at 90°direction. No difference was found on the semivariograms of eggs masses and larvae, which were shown as exponential curves. The semivariograms of pupae, egg masses and larvae at omnidirection were described by spherical model, indicating an aggregated spatial distribution. The strongest clumped spatial pattern was at pupae stage, and then, at larvae and egg masses stages. The semivariogram models of pupae,egg masses and larvae were simulated respectively. The isovalue maps of interpolated estimates of pupae, egg masses and larvae densities were generated by using Kriging techniques.

Effect of endogenous materials in cotton plant and JH analogs on alate rate of adult aphid and population dynamics

Zou Yunding, Li Jialin, Chen Gaochao, Hu Lijuan, Huang Shixiang, Wang Gongming, Zhou Xiazi, Wang Ziying, Meng Qinglei, Gen Jiguang

1997, 8(6):  617-622. 

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The study shows that the oleic acid, valine and proline in cotton plant has a significant effect on population dynamics, and the oleic acid, aspartic acid and serine in it had the some effect on alate of adult aphid. JHanalogs could produce a remarkable effect on the population dynamics and the alate rate of adult aphid.

Domestication of Tenualosa reevesii and its biology Ⅲ. Domestication of yearling reeves shad and its growth performance

Wang Hanping, Zhong Mingyuan, Mai Jiabo

1997, 8(6):  623-627. 

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Experiments on domestication of yearling reeves shad show that after using different domestication methods, its mean monthly body length and body weight are increased 18.9 mm and 24.09 g, growth index varies with season and water temperature, being rather high during early summer and late autumn when mean water temperature is 29～30℃, and growth rate is positively correlated with the biomass of zooplankton in the pond. After 8 months extensive rearing in a large pond, its mean body weight reaches to 496.3 g, and the output of it intensively reared in two ponds reaches to 1170 and 1087.5 kg·hm^-2, with a mean body weight of 203.3 and 201.3 g, respectively. The experiments show that artificial culture of reeves shad in pond is feasible.

Experimental studies on polyculture of Chinese shrimp with Taiwan red tilapia in fertilized seawater pond

Tian Xiangli, Wang Jiqiao, Li Deshang, Dong Shuanglin

1997, 8(6):  628-632. 

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Chinese shrimp (Penaeus chinensis) was polycultured with Taiwan red tilapia (Oreochromis mossambicus×O.niloticus) in 8 fertilized land based enclosed seawater ponds. When the density of shrimps was 0.92～2.36·m^-2 ,their survival rate was 75.72～89.98%, the yield ranged from 11.4 to 24.2 g·m^-2 after cultured for 91 days, and the productivity was 0.239 g·m^-2·d^-1. When the density of fish was 0.24·m^-2 , the stocking ratio of fish to shrimp was 1:10 , and the optimal stocking density of shrimps was 2.40·m^-2.

Ecoevolutionary analysis of Guangzhou suburban landscape

Li Zhen, Liu Jingyan, Zhang Baochun, Li Haiyan

1997, 8(6):  633-638. 

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The characteristics of the structure,function and existing ecoevolutionary stage of near,middle and distant suburban landscapes of Guangzhou city were quantitatively described. According to the changing patterns of the landscapes,their sefl organized ecoevolutionary series was defined,i.e.,natural landscape→rural landscape→urban rural dualized landscape→urban rural integrated landscape→urban landscape.

Ecological effect of exotic Cd-Zn compound pollution on purple soil

Zhu Bo, Qing Changle, Mu Shusen

1997, 8(6):  639-644. 

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Pot experiment and field investigation were conducted to study the effect of Cd-Zn compound pollution on purple soil cropped with wheat, lettuce, tomato and cabbage. The results show that Cd-Zn compound pollution has a synergistic effect on Zn. Low content of Cd can promote Zn uptake, exasperate its inhibition on nutrient absorption and aggravate Zn toxicity. Conversely, Cd-Zn compound pollution has an antagonistic effect on Cd. High content of Zn can restraine Cd uptake, reduce its inhibition on nutrient absorption, and thereby, alleviate Cd toxicity. Application of 500 mg Zn·kg^-1 soil is the threshold of antagonistic effect under pot experimental condition.

A preliminary study on the effect of municipal sludge on crop seed germination and seedling growth

Mo Cehui, Wu Qitang, Zhou Youping, O.C.Gaston

1997, 8(6):  645-649. 

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Studies on the effect of different municipal sludges on seed germination and seedling growth of Ipomoea aquatica and Brassica parachinensis show that the original sludges from Shenzhen and Foshan and the original sludge and its compost from Guangzhou were observed to be inhibitory to the germination of , but ameliorative to that of B.parachinensis seed. The same sludges and compost were found to be inhibitory or even harmful to the seedling growth of both I.aquatica and B.parachinensis. Organic acids and aldehydes in the sludges and compost were the major compounds inhibitory to the seed germination and seedling growth. Digestion and composting could degrade these organic matters, and hence, attenuate or eliminate the inhibitory effect of original sludges, which can be used as a practical way of the safer agricultural application of sludges. Immediate dissemination of crop seeds to newly-sludge-fertilized land is not recommendable.

Heavy metals content in sea water and marine organisms at Jiaozhou Bay

Cui Yi, Chen Bijuan, Song Yunli

1997, 8(6):  650-654. 

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The results show that heavy metal pollution in sea water along the estuary of Jiaozhou Bay is mainly from the discharge of industrial wastewater nearby the estuary. The heavy metals content in marine organisms is affected not only by the content of heavy metals in sea water, but also by temperature. Benthons have a higher heavy metals content than fish, and marine organisms enriche more copper than other heavy metals.

Effect of monocrotophos on ultrastructure Penaeus chinensis cells Ⅲ. Toxicity to gill

Ru Shaoguo, Li Yongqi, Liu Xiaoyun, Jiang Ming

1997, 8(6):  655-658. 

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Electron microscopic examination shows that after treated with 0.10 mg·L^-1monocrotophos for 96 hours, the gill cell of Penaeus chinensis has an obvious ultrastructural variation:the parallel, ordered structure of muscle fibres is destroyed,endoplasmic reticulum is swollen up, dilated and vesiculated,and ribosomes on the surface of RED is chipped away in large numbers. In golgi body, the dictyosomes is swollen up,and vesicles is dilated and even broken up. Cristaes in mitochondria is slightly swollen up, and disintegrated partially. Cuticle of gill fibre is denatured and dropped off, and nuclear membrane is swollen up and partially dissolved.

Effect of low pH, Al and Ca on toxicity and superoxide dismutase(SOD) activity of Cortinarius russus

Yin Daqiang, Jin Hongjun, Sun Ailong, Kong Fanxiang, Zhuang Suxing, Li Yujing

1997, 8(6):  659-662. 

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In this paper, acute bioassay method was used to study the toxic effect of low pHand aluminum on mycorrhizal fungi (Cortinarius russus). At pH 4.3, the aluminum toxicity was the strongest, with a 96 h EC₅₀ of 5.05 mg·L^-1, and the growth of Cortinarius russus was obviously inhibited. The SOD activity of Cortinarius russus was induced by low pH and aluminum, and increased obviously, but decreased when calcium was added, and decreased with increasing calcium concentration. At low pH, there exists an antagonism between calcium and aluminum.

Principles of ecosystem and sustainable agriculture

Duan Shunshan, Luo Shiming, Cai Kunzheng

1997, 8(6):  663-668. 

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Several agricultural ecosystem principles such as the law of energy flow and matter cycle,correlation of ecosystems,symbiosis and allelopathy,tolerance limit,structure and function,ecosystem opening,limiting factors,integrated function of ecosystem,biological competition and competitive exclusion,etc.,are discussed in this paper.It is suggested that Chinese ecological agriculture is a kind of typical sustainable agricultural system,and should be powerfully carried out in the course of national sustainable agricultural development.