Salt Contents in Soils Under Plastic Greenhouse Gardening in China

Field experiments were conducted on three main soils, brown soil, meadow soil and cinnamon soil, of Shandong Province to study the effect of plastic greenhouse gardening on soil salt contents. As compared to the open fields, the soil nutrient contents in the fields under plastic greenhouse gardening all increased significantly. The organic matter, quickly available N and P increases were extremely significant and the quickly available K increase was also significant. Along with the nutrient increases the soil salt contents increased clearly in all the soils investigated not only in the top layer but also in the deeper layers, being extremely significant in the 0～10 cm layer and significant in the 10～40 cm layers. The salt contents in the plastic greenhouses had significant correlations with the soil available nitrogen and phosphorous. Soils with longer plastic greenhouse gardening time tended to have more salt. The plastic greenhouse soils contained less CO-3～(2-) and much more NO-3 than the open soils, which indicated a higher influence of human intervention in plastic greenhouses. Among the constituent ions, Cl～(-), NO-3～(-) , Ca～(2+) and Mg～(2+) had positive while HCO-3～(-) had negative significant or extremely significant correlations with total salt, with correlation coefficients being 0.66*, 0.80**, 0.92**, 0.80** and -0.64* , respectively. Nitrate decreased from the top to deeper layers both in the plastic greenhouses and in the open fields. The plastic greenhouse soils contained much more nitrate than the open fields in every layer and even the nitrate contents of the 80～l00 cm layer were still several times those of the top layer in the open fields. The main reason for the salt increases was considered to be the inappropriate fertilization and selective absorption of nutrients by plants in the plastic greenhouses. The methods recommended to avoid soil salt increase in the plastic greenhouses were to apply fertilizers rationally according to the soils, vegetables and fertilizer properties and to adopt a good intercropping or rotation system.

Cultivated Land Changes and Their Driving Forces——A Satellite Remote Sensing Analysis in the Yellow River Delta,China

Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.

Utilizing Landsat TM Imagery to Map Greenhouses in Qingzhou, Shandong Province, China

To build a rapid and accurate method for greenhouse vegetable landinformation extraction using an index model derived from TM digital data of Qingzhou City, ShandongProvince, based on a systematic analysis of the spectral characteristics of different land use typesin the study area, a subset of the image was first made to eliminate the mountainous region notassociated with vegetable distribution, and then water body pixels were masked. With this the V_Iindex model for greenhouse vegetable land extraction was developed. The index model indicatedgreenhouse vegetable land for Qingzhou in April 2002 was concentrated in the southeast and aroundrural residential areas. Field data used for an accuracy evaluation showed that greenhouse hectaresdetermined with remote sensing were 95.9% accurate, and accuracy for the spatial distribution ofgreenhouse vegetable land cross checked with a random sample was 96.3%. Therefore, this approachprovided an effective method for greenhouse vegetable land information extraction and has potentialsignificance for management of greenhouse vegetable production in the study area, as well as NorthChina.

The Study on the Effects of Chinese Herbal Mixtures on Growth,Activity of Post-Ruminal Digestive Enzymes and Serum Antioxidant Status of Beef Cattle

Sixteen Limousin×Luxi crossbred beef cattle [（199.4±8.67） kg] were used to evaluate the effects of Chinese herbal mixtures （CHM） on growth, activities of post-ruminal digestive enzymes and serum antioxidant status of beef cattle. Treatments were control （no CHM supplementation） and three formulations of CHM （CHM-A, CHM-B and CHM-C） that were arranged as completely randomized design. The calves were fed in indoor individual feeding barn with total mixed ration for 90 d. The CHM-A, CHM-B, and CHM-C was incorporated into the diet at the level of 20 g kg-1 DM （dry matter） of concentrate. The cattle were weighted at the beginning, at the end and every 15 d between to determine growth rate. Blood sample was taken every 30 d to analyze activities of total superoxide dismutase （T-SOD） and glutathione peroxidase （GSH-PX） and concentration of malondialdehyde （MDA）. The cattle were slaughtered at the end of experiment and chymus samples from various section of the post-ruminal digestive tract were collected to analyze enzymes activities. All cattle had similar average daily gain, but cattle supplemented with CHM-A tended faster growth （P=0.08） compared to the control and other CHM treatments. Supplementation of CHM did not affect pH of chymus in any section of the post-ruminal digestive tract. Activities of pepsin, trypsin, chymotrypsin, and lipase in chymus samples were enhanced （P0.05） to various extents by supplementation of CHM-A, CHM-B, and CHM-C depending on the enzymes and the site of the digestive tract. Amylase activity was increased only by CHM-A and CHM-C from chymus sample collected at the ileum. Supplementation of CHM-A and CHM-B reduced （P0.05） concentration of MDA, but did not affect GSH-PX activity in the serum of cattle throughout the entire experimental period. Cattle supplemented with CHM-B also had higher （P0.05） T-SOD activity in the serum at day 30 and 60 as compared with the control and the other two CHM treatments. Chinese herbal mixtures supplemented at the levels of 20 g kg-1 DM of concentrate increased post-ruminal digestive enzymes activity and enhanced serum antioxidant status. Inclusion of CHM-A and CHM-B in the diet may be favourable for ruminant production.

Studies on Manganese Peroxidase Immobilized in Gelatin-containing Microemulsion-based Gels

The immobilized technique of manganese peroxidase(MnP) in gelatin-containing microemulsion-based gels and the effects of storage time and reuse times on its catalytic activity were studied. The results show that the MnP immobilized together with Mn 2+ and H_2O_2 could effectively oxidize syringaldazine in n-heptane. The immobilized MnP still had a high catalytic activity after one-month storage under a freezing condition. The reuse times have a relation to the amount of the immobilized H_2O_2. When the amount of the immobilized H_2O_2 is sufficient, the microemulsion-based gels containing MnP could be used many times.

Photosynthetic Characteristics and Ultrastructure of Chloroplast of Cucumber Under Low Light Density in Solar-Greenhouse

The photosynthetic characteristics and ultrastructure of chloroplast of cucumber in solar-greenhouse were studied. The result showed that the photosynthetic rate (Pn), photosyntheticability (A350), carboxylation efficiency, light saturation point and light compensation pointall declined remarkably under low light density, indicating that the photosynthetic characteristicsof cucumber were closely related to light environment. Under low light density, the minimalfluorescence (Fo), alterable fluorescence (Fv), photochemical efficiency of PSⅡ(Fv/Fm), steadyfluorescence in light (Fs), maximal fluorescence (Fm) and actual efficiency of PSⅡ(φPSⅡ)etcincreased, indicating that the photochemical activity and efficiency for solar energy transformationenhanced, thus the light proportion used to electron transport also increased. The chlorophylla, b, a/b and carotenoid of shading leaves decreased. However, the depressed extent of Chl a andChl a/b were obviously larger than that of Chl b. The number of chloroplast and starch grainin cucumber leaves descended, but that of grana and lamella increased as a shaded result. Thesize of chloroplast and starch grain of shading leaves minished.

Identification of Co-Segregating RAPD Marker Linked to Powdery Mildew Resistance Gene Pm18 in Wheat

The Pm18 gene of wheat confers resistance to the powdery mildew which is one of the mostserious diseases in many regions of the world. In this study, bulked segregant analysis(BSA) was used to develop randomly amplified polymorphic DNA (RAPD) markers linked toPm18 gene. Three hundred and twenty decamer primers were screened and one of them wasidentified as RAPD marker (S411600) linked to Pm18. Using the F2 mapping population fromthe cross Pm18Chancellor, the marker S411600 was shown to co-segregate with the genePm18. This marker can be conveniently used for marker-assisted selection in wheatbreeding programs for the identification or pyramiding of Pm18 with other resistancegenes.

STUDY ON THE FRAMEWORK SYSTEM OF DIGITAL AGRICULTURE

China is a great agricultural country with large population, limited soilresources and traditional farming mode, so the central government has been attaching greatimportance to the development of agriculture and put forward a new agricultural technologyrevolution ― the transformation from traditional agriculture to modern agriculture and fromextensive farming to intensive farming. Digital agriculture is the core of agriculturalinformatization. The enforcement of digital agriculture will greatly promote agricultural technologyrevolution, two agricultural transformations and its rapid development, and enhance China'scompetitive power after the entrance of WTO. To carry out digital agriculture, the frame system ofdigital agriculture is required to be studied in the first place. In accordance with the theory andtechnology of digital earth and in combination with the agricultural reality of China, this articleoutlines the frame system of digital agriculture and its main content arid technology support.

Inhibitory Effects of Kojic Acid on Phenoloxidase of Diamondback Moth Plutella xylostella

The effects of kojic acid on phenoloxidase (PO) of Plutella xylostella were investigated, when it had been partially purified by 40% saturated [(NH4)2SO4] and Sephadex G-100 gel filtration. Kojic acid showed inhibitory effects on both monophenolase and o-diphenolase activity of the PO. The inhibitor concentrations leading to 50% (IC50) activity lost were estimated to be 0.07 mmol L-1 for monophenolase and 1 mmol L-1 for diphenolase, respectively. Kojic acid can also prolong the lag time of PO for oxidation of L-tyrosine. The inhibition kinetics were analyzed by Lineweaver-Burk plots and kojic acid was found to be a reversible competitive inhibitor with the Ki of 0.47 mmol L-1. The ability of kojic acid to inhibit the enzyme activity may be associated with its ability to chelate copper at the active site. In addition, the iron ion was found to shorten the lag time obviously, but have no important effect on the monophenolase activity.

Creating New Germplasm by Distant Hybridization in Stone Fruits:Ⅱ-Embryo Rescue and Hybrid Identification Between Plum and Apricot

Embryo abortion stage and rescue system of hybrids were studied in the distant hybridizationbetween plum and apricot. Identification of the hybrids was also made. The resultsshowed: (1) Embryo abortion started from three weeks after pollination. (2) The germinationand growth of embryos were different at different growth stages, which could germinateand grow with PF value>0.5, but failed with PF value<0.5. In embryo rescue system ofhybrids, the best germination and differentiation medium was MS+6-BA 2mgL-1+IAA 0.3mgL-1,the rate of germination and differentiation reached up to 80%, bud induction andmultiplication medium was MS+6-BA 1.5mgL-1+IAA 0.3mgL-1, rooting medium was 1/2 MS+IAA0.8mgL-1. Some hybrids were transplanted into the field successfully. (3) Leaf shapeinvestigation and identification by S allele-specific PCR and RAPDs showed that thehybrids were true ones.

Creating New Germplasm by Distant Hybridization in Stone Fruits:Ⅰ.Effects of Different Treatments on Cross Compatibility of Distant Hybridization inStone Fruits

The effects of different treatments on cross compatibility in distant hybridization werestudied in 69 cross combinations among 9 cultivars of stone fruits. The results showedthat the setting percentage in balloon stage was obviously higher than that in earlyblooming stage. The differences of fruit set between positive and reverse crosses weresignificant. Female parent affected cross compatibility more remarkably than male parentin distant hybridization. The appropriate electrostatic field, He-Ne laser combinedtreatment with 60Co γ-ray and He-Ne laser could improve the pollen germination rate invitro effectively, the fruit set percentage was higher than control, while 60Co γ-raytreatment reduced the pollen germination rate in vitro, and the fruit set percentageobtained by distant hybridization was lower than control.

Effects of Plant Density on Forage Nutritive Value of Whole Plant Corn

In the field experiment, the effects of plant densities (75 000, 112 500 and 150 000 plants ha-1) on forage nutritive value of whole plant corn (WPC) were studied from 1999 to 2001. The results demonstrated that with the increasing of plant density, the forage matter yield per plant corn decreased significantly, while the fresh matter and dry matter per hectare corn increased significantly, and a higher grains yield was gotten at higher plant densities. Forage nutritive quality of whole plant corn was changed as plant density increased, the crude protein (CP), ether extract (EE), crude fiber (CF), nitrogen free extract (NFE) and general energy (GE) yields increased obviously. Increas- ing plant density reasonably with the application of plant growth regulators could improve plant properties, harvest more forage matter, and enhance forage nutritive value of WPC.

SA Induction of aGrapevine ClassⅢChitinase Gene VCH3 Promoter in Transgenic Tobacco Vascular Tissue

The 1216bp5’upstream region of the gene encoding the class Ⅲ chitinase VCH3 was isolated from grapevine(Vitis amurensis Rubr．)(Genbank accession number AF441123)and two inverse salicylic acid(SA)responsive cis-acting motifs(TGACG)were found at-1181bp and-293 bp upstream of the transcriptional start site．respectively．To characterize the vcH3promoter，four chimeric constructs varied in the length of promoter fragments from-1187bp，-892bp，-589bp and-276bpto+7bp relative to the transcriptional start site were placed to the upstream of the β-glucuronidase(GUS)coding region and transferred to Nicotlana tobacum L．CV．NC89 by Agrobacterium tumefaciens-mediated leaf discs transformation．The functional properties of each promoter fragment were examined by fluorometric and histochemical analysis of GUS activity in the transgenic tobacco root treated withSA．The VCH3(-276)GUS construct．containing only the TATA and CAAT boxes was shown to have little inducibility upontreatment with SA．However，the similarly higher level of GUS expression was observed in the VCH3(-589) GUS or VCH3(-892) GUS transgenic plants with only one cis-acting motif,while the most abundance of GUS expression was found in the full-1ength promoter(-1187bpto+7bp)with two cis-acting motifs．The seresults indicated that the twocis-acting motifs werere quired for the maximal expression of the GUS reporter gene by SA induction．In addition，the histochemical analysis of GUS activity showed that the four VCH3 promoter fragments were more active in vascular tissue than that in outer and inner cortexes of the transgenic tobacco roots treated by SA，suggesting that the region involved in vascular tissue-specific expression of VCH3 promoter upon SA inducibility appears to belocated between positions-276 bp and+7bp relative to the transcriptional start site．In general，these results indicate a potential use for the SA induction of VCH3 promoter in genetic engineering．

Activities of the Enzymes Involved in Starch Synthesis and Starch Accumulation in the Grains of Wheat Cultivars, GC8901 and SN1391

Two wheat cultivars, GC8901 (hard winter wheat) and SN1391 (soft winter wheat), were used for investigating the changes of enzyme activities for sucrose metabolism and starch biosynthesis and the accumulation character of starch composition. The result showed that activities of sucrose (SS), sucrose-phosphate synthase (SPS), adenosine diphosphorate glucose pyrophrylase (AGPase) and soluble starch syntheses (SSS) of 1391, which have more starch, were significant higher than those of 8901, that with low starch content. But the changing of granule-bound starch synthase (GBSS) activity was consistent with the amylose content, which indicated that amylose contents in grain were determined by GBSS activity, especially the activity at later grain filling stages. Simulating with Richards equation showed that it was initiating time and accumulation rate, but not accumulation duration that determined the content of starch composition. Furthermore, changing of sucrose transport capacity was consistent with SSS and GBSS activities, starch accumulation rate was accordant to AGPase and SS/SPS ration, not SS, SPS, SSS or GBSS activities. The results suggested that there was no inevitable relation of starch accumulating rate and starch composition contents with the activity of single enzyme such as SS, SPS, SSS or GBSS, but closely related to AGPase activity and SS/SPS ratio, and it was SPS and AGPase that play a vital role in the biosynthetic pathway. Later polymerization reactions catalyzed by SSS and GBSS don’t seem to control the rate of starch accumulation, but do affect starch structure.

Comparison of Different Dough Rheological Measurement and Path Coefficient Analysis of Bread Quality

Farinograph, extensograph and mixograph are the special instruments used to determinedough rheological characteristics. In this study, twenty-seven wheat cultivars ofdifferent gluten strength were used to study the correlations among each rheologicalparameter determined by above instruments. Multiple linear regression analysis and pathcoefficient analysis were used to study the direct and indirect effects of 11 doughrheological characteristics on bread quality. The results showed significant correlationsamong the principal parameters. There were significantly or extremely significantlypositive correlations among development time (DT), stability time (ST), farinographquality number (FQN) of farinograph, area, maximum resistance (Rmax), viscoelastic ratio(Rmax/E)of extensograph and mixing time (MT), 8-minute-curve-tail (8MCT) of mixograph.These indexes affected bread-making quality either directly or indirectly. Of all theindexes, ST, maximum Rmax, MT and FQN were the most important ones.

Effects of Different Nitrogen Application Strategies on Yield and Forage Nutritive Quality of Zea mexicana

A pool experiment was carried out to study the effects of different nitrogen applicationstrategies (rates and stages of nitrogen application) on yield and forage nutritivequality of Zea mexicana cultivated in summer, 2002. In the whole growing stage, its stemwas clipped three times at the height of 25cm when it was 110cm high (H1, H2 and H3 standfor the first, second and third harvest stage, respectively). Six indexes includingcrude protein (CP), ether extract (EE), nitrogen free extract (NFE), acid detergentfiber (ADF), crude ash (CA), and general energy (GE) were employed to evaluate the foragenutritive value. The results showed that the content of CP and EE increased but thecontent of CA and ADF decreased under the two nitrogen rates (High-rate N, 600kgha-1;Mid-rate N, 300kgha-1). The fresh and dry harvest biomass of the whole plants on H1 andthose of the leaves on H2 were also improved. But the stalks on H2 and the whole plantson H3 were affected mainly by dressing nitrogen fertilizer. The yield of CP and EE, CA,NFE, and GE was mainly affected by nitrogen rates. The ADF yield increased was due to theincrement of the fresh and dry harvest biomass. Nitrogen applied as base fertilizer forsummer Zea mexicana can be harvested a higher biomass and improve the forage nutritivequality.

Effects of Tillage Management Systems on Residue Cover and Decomposition

The effects of tillage methods on percent surface residue cover remaining and decomposition rates of crop residues were evaluated in this study. The line transect method was used to measure residue cover percentage on continuous corn ( Zea mays L.) plots under no tillage (NT), conventional tillage (CT), chisel plow (CH), and disk tillage (DT). Samples of rye ( Secale cereale L.) and hairy vetch ( Vicia villosa Roth) were used for residue decomposition study. Results showed that the percentage of residue cover remaining was significantly higher for NT than for CH and DT and that for CT was the lowest (<10%). For the same tillage system, the percent residue cover remaining was significantly higher in the higher fertilizer N rate treatments relative to the lower fertilizer N treatments. Weight losses of rye and vetch residues followed a similar pattern under CT and DT, and they were significantly faster in CT and DT than in NT system. Also, the amounts of residue N remaining during the first 16 weeks were always higher under NT than under CT and DT.

Analysis of Seed-expressed Sequence Tags in Triticum aestivum

To isolate seed-expressed sequences, a cDNA library was constructed using wheat ( Triticumaest/vum L) seed tissues at 12 d after pollination. Plasmid DNAs of 10 000 clones randomly picked out fromthe library were prepared. The preparation of high density filters were made with the Biomek 2000 HDRTsystem, and then hybridized separately with three probes prepared by reverse transcription of RNA ofunpollinated ovary, embryo and endosperm. Based on the hybridization results, 800 clones expressed inembryo and/or endosperm were chosen for further analysis of expressed sequence tags (ESTs). Finally,216 different genes were identified preliminarily. Of them, 24 (11.5%) were considered identical to knownwheat genes, 122 (56%) were identified as putative new plant genes which may be involved in seed storageproteins, biochemical metabolisms, development, and other biological processes of seeds, while 70 (32.5%)sequence identities could not be determined.

PERIODICITY IN A DELAYED SEMI-RATIO-DEPENDENT PREDATOR-PREY SYSTEM

A delayed semi-ratio-dependent predator-prey system in a periodic environment is investigated in this paper.By using a continuation theorem based on Gaines and Mawhin's coincidence degree,the global existence of positive periodic solution is studied.A set of easily verifiable sufficient conditions are obtained.

Changes in Cell Ultrastructure in Maize Leaves Infected by Maize Dwarf Mosaic Virus

Ultrastructural alterations in foliar cells were studied in leaves of resistant maize variety Luyu16 and susceptible maize inbred line Luyuan92 infected by maize dwarf mosaic virus Shandong isolate (MDMV-SD), respectively. The results showed that marked cytopathological alterations were observed both in resistant plants and in susceptible plants, compared with that in healthy plants. However, some ultrastructural alterations, which observed in resistant plants, were different from those in susceptible plants. In resistant plants, which infected with the virus, the main organelles, including chloroplasts and mitochondria, were slightly destroyed, the amount of mitochondria and peroxisome were increased. A few or no plasmodesmata were observed. There were three kinds of inclusions including pinwheel, bundle and laminated aggregate, and the virus particles in the cytoplasm. In susceptible plants, which infected with the virus, the chloroplasts were heavily disrupted, including thylakoid swelling and envelope broking. The virus particles were more than those in the resistant variety. Four kinds of inclusions including pinwheel, bundle, laminated aggregate and high electon-dense body appeared in cytoplasm. Plasmodesmata and plasma membrane were abundant, and there were frequent invaginations of the plasma membrane that led to the formation of vesicles and myelin-like structures.