• Volume 33,Issue 2,2014 Table of Contents
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    • >Crop genetic improvement and cultivation
    • Comparative mapping of quantitative trait loci for heading date in rice under long-day and short-day conditions using a recombinant inbred line population

      2014, 33(2):1-7. DOI: 1000-2421(2014)02-0001-07

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      Abstract:A population of recombinant inbred lines derived from the cross between rice varieties Zhenshan 97 and Minghui 63 was examined for heading date in two plantings (winter in Hainan and summer in Wuhan) to analyze QTLs for heading date using an ultra-high density SNP linkage map.Comparison of the results from the short-day Hainan winter and long-day Wuhan summer revealed large differences of QTLs between the two conditions.The main QTL for heading date in long-day environment of Wuhan was detected near the centromere of chromosome 7,but its effect was not significant in Hainan short-day environment.In contrast a major QTL for heading date was detected in the region of 9.12-9.65 Mb on chromosome 6 in Hainan but its effect was not significant in Wuhan conditions.The results will be useful for understanding the genetic basis of rice flowering.

    • Transforming rice (Oryza sativa L.) with a Vitis stilbene synthase gene

      2014, 33(2):8-14. DOI: 1000-2421(2014)02-0008-07

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      Abstract:Two resveratrol synthase genes from different Vitis spp.were isolated and replaced under the control of Ubiquitin promoter,respectively.The vectors were then introduced into japonica rice cultivar ZhongHua 11 through Agrobacterium-mediated gene transformation.Analyses of Southern blot and RT-PCR confirmed that the introduced genes were expressed stably in most of different single-copy gene transformants.Based on the HPLC-MS analysis,a major resveratrol derivative,piceid (resveratrol-glucoside) was detected in the leaves of the single-copy gene transformants with the highest content of 10.26 μg/g fresh weight,1 000-fold more than that of the wild type control.Resuls indicated that resveratrol produced by the exogenously integrated gene might be metabolized into piceid by the endogenous glycosyltransferase.Although these transformants did not show significant resistance towards Magnaporthe grisea,they may have some beneficial effects on human health with the high content of piceid.

    • De novo assembly of teosinte seedling transcriptome defined by RNA-Seq

      2014, 33(2):15-21. DOI: 1000-2421(2014)02-0015-07

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      Abstract:Teosinte is the ancestor of maize,and plays an important role in maize domestication process and gene cloning.Solexa RNA-Seq was used to de novo assembly and analyze the transcriptome of teosintes.40.6 GB raw data were produced,including 175 101 250 reads of 76 bp length.After quality control and de novo assembly,58 147 teosinte transcripts with an average length of 1 335 bp were obtained.After bioinformatically comparing,it was found that 94.3% of teosinte transcripts had good matching with B73 cDNAs,and that 84.1% of the transcript had good matching with rice,84.6% with sorghum and 83.9% with brachypodium at protein level.This research will provide a reference for subsequent studies on maize evolution and gene discovery.

    • Histological analysis of somatic embryogenesis and plant regeneration in Gossypium hirsutum Lumian 6

      2014, 33(2):22-27. DOI: 1000-2421(2014)02-0022-06

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      Abstract:An efficient somatic embryogenesis system was developed to regenerate plantlets from hypocotyls of upland cotton cultivars Lumian 6(Gossypium hirsutum L.).The cultivar Lumian 6 was cultivated in North China,the same cotton planting region as YZ1,an easy-going genotype somatic embryogenesis.Calli were produced on the medium with twelve different hormone regimes,the hormone regimes 1.0 mg/L IBA only or 0.1 mg/L 2,4-D together with 0.2 mg/L KT were the best for inducing calli from Lumian 6.After about 4 weeks,the peripheral cultures were separated from explants and transferred to fresh MS medium with half auxin and doubled KNO3.After two to three subcultures (30 days intervals),friable,yellow-green or grey-green embryogenic cultures and somatic embryos was effectively observed in ECM media with low concentration of auxin (0.01 mg/L 2,4-D and 0.1 mg/L KT or 0.1 mg/L IBA only).After being transferred to the media for differentiation and embryo-germination,somatic embryos were produced and further developed.The two varieties can regenerate plantlets in 6-8 months using the protocols mentioned above.Histological observation demonstrated that the majority of embryogenic calli originated in a familiar way in the two genotypes and proved that the cells from primary cambium cells were the original cells for forming cotton embryogenic calli.

    • >Microbiology
    • Screening proteins interacting with the outer membrane protein Opa22 in Mesorhizobium huakuii 7653R with bacterial two-hybrid library

      2014, 33(2):28-33. DOI: 1000-2421(2014)02-0028-06

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      Abstract:Opa22 is an outer membrane protein identified in Mesorhizobium huakuii 7653R in our previous work.To investigate its functions during symbiotic nitrogen fixation,a random genomic DNA library of M.huakuii 7653R based on the bacterial two-hybrid system was constructed.The candidate proteins interacting with Opa22 were screened from the library and twelve positive clones were obtained and analyzed.This study will provide both new insights on understanding Opa22 functions during symbiosis and technique platforms for the further researches on the protein-protein interaction network as well.

    • >园艺.林学
    • Distributions of both male cones and female cones in crown and ratio of pollen to ovule in seed orchard of Pinus Massoniana located in Taizishan

      2014, 33(2):34-39. DOI: 1000-2421(2014)02-0034-06

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      Abstract:Distributions of both male cones and female cones in a tree crown and the ratio of female-male gamete were studied in Pinus massoniana clone seed orchard located in Taizishan,Hubei Province.The results showed that there were significant differences among the quantity of both male cones and female cones in the tree crown.The average number of male cones was 1 009.09,ranging from 291.61 to 1 549.69 per tree whereas the average number of female cones was 343.91,ranging from 135.43 to 636.39 per tree.The ratio of male cones to female cones was ranged from 0.14 to 1.07 for different clone mother trees.The average pollen number per sac,the average pollen per tree and all pollen in seed orchard was 16 513.33,3.75×1011 and 2.03×1015,respectively.There was a significant difference for pollen yield among different clone trees.The average ovule number per female cone,average ovule number per tree and all ovule in seed orchard was 177,60 872.07 and 3.29 billion,respectively.The ratio of pollen to ovule for the seed orchard of P.massoniana studied was about 1 to 6.16×106.The seed yield in this seed orchard could theoretically reach to 4 115.53 kg.

    • >Plant protection
    • Analysis of the genetic diversity of Xanthomonas axonopodis pv.dieffenbachiae in Guangdong Province

      2014, 33(2):40-45. DOI: 1000-2421(2014)02-0040-06

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      Abstract:The evaluation of genetic diversity of 66 Xanthomonas axonopodis pv.dieffenbachiae (Xad) strains from 27 anthurium varieties in 9 cities from Guangdong Province was conducted by Rep-PCR technology. The DNA of Xad was amplified by the primer ERIC and the genetic diversity was evaluated by UPGMA clustering analysis. The results showed that 66 Xad strains could be divided into 14 genetic groups at the similarity level of 0.85, and the genetic group Ⅰ,Ⅱ and Ⅹ were the major groups. It shows that there were obvious differentiation and rich diversity in X.axonopodis pv.dieffenbachiae strains in Guangdong Province.

    • Influence of ultraviolet light irradiation on HMG-CoA reductase,vitellogenin mRNA expression and oviposition of Helicoverpa armigera

      2014, 33(2):46-50. DOI: 1000-2421(2014)02-0046-05

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      Abstract:The objective of this study is to investigate the relative expression of HMG-CoA reductase (hmgr) and vitellogenin (vg) mRNA of Helicoverpa armigera adults under UV light irradiation, together with the fecundity variation of UV light irradiation group. Quantitative real-time PCR (qPCR) technique was applied to detect the expression of hmgr and vg of H.armigera of the UV light irradiation group. Total RNA was extracted from the whole body of H.armigera,and synthesized to cDNA via reverse transcription. Specific primers on hmgr,vg and β-actin in GenBank were used to carry out qPCR. In addition,this study also recorded the number of the eggs for female adults after UV light irradiation. The expression of hmgr of H.armigera significantly increased after the exposure to UV light irradiation from 0.5 h to 5.0 h, which was higher than that of control after UV light irradiation, while the vg expression increased 24 h later after UV light irradiation. The results also suggest that the fecundity of female adults significantly increased after UV treatment of 1.0 h to 4.0 h. This study is the first analysis of differentially expressed mRNAs in phototactic insects under UV light irradiation conditions and gives new insights into the adaptation mechanisms responsive to UV light irradiation stress. 

    • New resistance identification method and resistance evaluation of sugarcane varieties to smut disease

      2014, 33(2):51-56. DOI: 1000-2421(2014)02-0051-06

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      Abstract:In order to develop a new resistance identification method of sugarcanes to smut disease,caused by the fungus Ustiliago scitaminea Sydow, and provide technical support to breeding of smut resistant sugarcanes,single teliospore of Ustiliago scitaminea Sydow was isolated and cultured, mating type of sporidia was also identified,by using a 1∶1 mixture (plus and minus) mating types as inoculum.Injection inoculation was carried out at the growing point or young stem below it in younger sugarcane seedlings,and the concentration of mating type (plus and minus) and injection volume were optimized in this study. The results showed that comparatively the most suitable mating type concentration was 5×105 sporidia/mL,the relatively appropriate injection volume was 90 μL per plant in injection inoculation method. In comparison with common dipping inoculation,injection inoculation has a shorter latent period,high incidence,and it is possible to sufficiently evaluate resistance level of host and the type of physiological race. On this basis,twenty-two sugarcane varieties (materials) were inoculated by using the newly established injection inoculation and common dipping inoculation,the results showed that there were one susceptible variety,twenty-one high susceptible varieties by using injection inoculation method;however,one resistant variety,two moderately resistant varieties,eight susceptible varieties and eleven high susceptible varieties by using common dipping inoculation method.

    • Measurement of cell wall degrading enzymes from asparagus stem blight pathogen and its optimization of activity determination conditions

      2014, 33(2):57-60. DOI: 1000-2421(2014)02-0057-04

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      Abstract:To define the activity and optimize the determination conditions of the cell wall degrading enzymes from asparagus stem blight pathogen, the activities of 7 cell wall degrading enzymes were determined by the 3,5-dinitrosalicylic acid (DNS) method,the induced effects of different substrates were compared,and the determination conditions for 3 main enzymes were optimized in 3 aspects, i.e. temperature, time and pH value. The results revealed that in the 7 cell wall degrading enzymes the activity of polygalacturonase (PG) was the most vigorous,followed by polymethylgalacturonase (PMG) and endo-β-1,4-glucanase (Cx), whereas the other 4 enzymes were of lower activity. In the 3 main enzymes, 1% CMC was the better induced substrate for Cx and 1% pectin was the better for PG and PMG. In regarding to reaction temperature,it was found that the best reaction temperature for Cx was 50℃ and the best for PG and PMG was 50-60℃ and 60℃, respectively. In regarding to reaction time,it was found that 50 min was more suitable for Cx, whereas 60 min was more suitable for PG and PMG. In regarding to pH value,it was found that pH 4.0 was more suitable for Cx and PG, whereas pH 8.0 was more suitable for PMG.

    • Changes of defensive enzyme activities during the interactions of banana plantlets with Fusarium oxysporum f.sp.cubense race 4

      2014, 33(2):61-64. DOI: 1000-2421(2014)02-0061-04

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      Abstract:In order to investigate the changes of defensive enzyme activities in banana infected by Fusarium oxysporum f.sp.cubense race 4 (Foc 4), the activities of phenylalanine ammonialyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD) and catalase (CAT) were determined during the interactions of Fenjiao (ABB) and Brazilian (AAA) banana plantlets with Foc 4 by using artificial inoculation method of dipping injured-roots in conidial suspension. The results showed that the activities of PAL, POD, PPO and SOD were higher in the infected bananas than those in the corresponding non-infected controls, and the changes in activities of PAL, POD, PPO and SOD in infected bananas were more complicated than those in the corresponding non-infected controls, which suggested that these four enzymes actively participated in the resistant response in bananas during the infection of Foc 4. However, the variation trends of CAT activities in both infected and non-infected controls were general similar, indicating that the activity variation of CAT is not related to the infection of Foc 4.

    • Inhibitory effect of ammonium carbonate and ammonium hydrogen carbonate on blue mold of citrus fruits

      2014, 33(2):65-69. DOI: 1000-2421(2014)02-0065-05

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      Abstract:In this research use Penicilium italicum which causes the major loss of citrus fruits during storage and distribution as the research object,and in vitro and in vivo evaluation to determine the antibacterial activity of ammonium carbonate and ammonium bicarbonate. The effect of ammonium carbonate and bicarbonate on conidial germination and mycelium growth of P.italicum was evaluated. Inhibition of both compounds on disease incidence of citrus fruits either naturally or inoculated with the pathogen was also investigated. The results demonstrated that ammonium carbonate and bicarbonate demonstrated powerful inhibitory effect on spore germination and mycelium growth of the pathogen with the minimum inhibition mass fraction for spore germinations of 0.32% and 0.36% respectively. The inhibitory effect of both compounds on the pathogen was quite stable after the solutions were treated under different temperatures (4-100℃) for 30 minutes.Both compounds demonstrated strong inhibition with the media at neutral and alkaline pH. Both compounds at the mass fraction of 0.80% could significantly reduce the decay rates of citrus fruits either naturally or inoculated with the pathogen. 

    • First description of male Alulatettix bamianshanensis Fu et Zheng (Orthoptera:Tetrigoidea)

      2014, 33(2):70-71. DOI: 1000-2421(2014)02-0070-02

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      Abstract:The male of Alulatettix bamianshanensis Fu et Zheng,1998 is described in this paper.The specimens are deposited in Department of Chemistry and Life Science,Hechi University,China (8♂7♀).

    • >Resources and environment
    • Purification of combined pollution of heavy metals in micro contaminated water by Potamogeton crispus L.

      2014, 33(2):72-77. DOI: 1000-2421(2014)02-0072-06

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      Abstract:The accumulation and removal on combined pollution of Cd2+,Cr3+,Cu2+,Zn2+,Ni2+ and Mn2+ in micro contaminated water by submerged plant Potamogeton crispus were studied in small enclosures.Results showed that the removal of heavy metals in overlying water with the growth of P.crispus was significantly higher than that without P.crispus.P.crispus had different abilities to absorb heavy metals tested and super accumulation ability for Cd2+,Mn2+ and Ni2+.Mn2+ enrichment was the most significant indicating that P.crispus is an aquatic plant preferred manganese.The accumulation abilities of heavy metals were diverse among different parts of the plant.The enrichment of Cd2+ was stronger in leaves and the accumulation of Cr3+,Cu2+,Zn2+,Ni2+ and Mn2+ in new leaves were higher than those of the old leaves,roots and stems.

    • >Animal and veterinary
    • Effects of Bacillus subtilis and bursin on growth performance,serum biochemical indices and antioxidant indices of broilers

      2014, 33(2):78-82. DOI: 1000-2421(2014)02-0078-05

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      Abstract:This study was aimed to study the effects of Bacillus subtilis and bursin on growth performance,serum biochemical indices,and antioxidant indices of broilers.A total of one hundred and forty four 1-day-old Cobb-500 broilers were randomly allotted to four groups with three replications (twelve broilers in each replicate).The control group (group Ⅰ) was only fed basal diet.The bursin group (group Ⅱ) was fed basal diet and injected with bursin (0.01 mg/kg) at day 4 and day 7.Group Ⅲ was fed basal diet with Bacillus subtilis(1.0×106 cfu/g feed).Group Ⅳwas fed basal diet with B.subtilis (1.0×106 cfu/g feed) and injected with bursin (0.01 mg/kg) at day 4 and day 7.The trial lasted for 42 days.The results showed that the average daily gain in groupsⅡ,Ⅲ and Ⅳ were significantly higher than that in groupⅠ(P<0.05) at day 21 and day 42,while the F/G value in group Ⅳ was the lowest and decreased 4.37% compared with group Ⅰ(P>0.05).At day 21,contents of serum total protein in group Ⅲ and Ⅳrespectively increased 19.60% and 27.68%,comparing to group Ⅰ.At the same time,albumin contents in group Ⅲ and Ⅳrespectively increased 16.72% and 18.03%.The activities of CAT and GSH-Px in groupⅢ (on the 21th day) and Ⅳ (on the 42th day) were significantly higher than those in group Ⅰ(P<0.05).Contents of serum MDA in groupⅡ,Ⅲ and Ⅳ were significantly lower than that in group Ⅰ(P<0.05) at day 42.It was concluded that B.subtilis and when it combined with bursin could improve growth performance and increase contents of total protein and albumin in serum and the activities of CAT,GSH-Px.

    • Location and characteristics of melanocytes of black-boned goat skin

      2014, 33(2):83-88. DOI: 1000-2421(2014)02-0083-06

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      Abstract:This paper focused on location and characteristics of melanocyte in skin of black-boned goat,providing clues for melanin deposition research.By immunohistochemistry staining,the localization of melanocytes in the black-boned goat skin with different coat colors (black and white) was examined.The mature melanocytes were determined by DOPA staining.The morphology of melanocytes was analyzed using hematoxylin-eosin(HE) staining.The immunohistochemistry results showed that melanocytes were mainly located in basal layer of epidermis and hair follicles;The DOPA staining revealed that melanocytes were not identifiable in basal layer of the two coat colors epidermis and white hair follicles but existed in the bulb of black hair follicles and outer root sheath.It turned out that there were mature melanocytes existing in the bulb of black hair follicles and outer root sheath,which could synthesize melanin.The hematoxylin-eosin (HE) staining results suggested that melanocytes in the outer root sheath of black hair follicles had intense pigmentation and a tendency for vacuolization while melanocytes in white hair follicles were elliptical shape and produced no melanin.What’s more we can’t distinguish the melanocytes from the other surrounding cells.Therefore,the activation of the melanocytes in the outer root sheath of black hair follicles might be the main reason for the melanin trait of black-boned goat.

    • >Aquatic farming
    • Estimations of heritabilities and breeding values for growth traits in Megalobrama amblycephala

      2014, 33(2):89-95. DOI: 1000-2421(2014)02-0089-07

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      Abstract:The heritabilities and breeding values of growth traits (including body weight,body length and condition factor) for Megalobrama amblycephala were estimated using mixed family model in this study.The variance analysis of growth traits revealed that variance caused by parents was much greater than that caused by environment at six-month stage.The heritability of body length,body weight and condition factor were 0.72±0.21 (high heritability),0.49±0.14 (moderate heritability) and 0.48±0.14 (moderate heritability) (P<0.01),meaning that most of the variance for all the three traits was genetic.The phenotypic and genetic correlation coefficient between body weight and body length were 0.89 and 0.98 (P<0.01),which indicated the correlation between body and body length was caused by genetic.The rank of estimated breeding values varied but not too much among body length,body weight and comprehensive,and most of the top 20 individuals were Poyang population’s offspring.

    • Effects of dietary lipid levels on growth performance,activity and gene expression of lipoprotein lipase in GIFT tilapia (Oreochromis niloticus) juvenile

      2014, 33(2):96-102. DOI: 1000-2421(2014)02-0096-07

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      Abstract:A 90-day study was conducted to investigate effects of dietary lipid levels on performance,fat deposition,activity and expression of lipoprotein lipase (LPL) in GIFT tilapia (Oreochromis niloticus) juvenile,and to explore the correlation between LPL gene expression and fat deposition.315 GIFT tilapia juveniles(average weight 2.63±0.16 g) were randomly divided into three groups with three replications,and fed with isonitrogenous diets with different lipid levels of 3.7% (low-lipid group),7.7%(middle-lipid group)and 16.6% (high-lipid group) by supplementing with 2%,6% and 15% fish oil as lipid source,respectively.The results showed:(1) the hepatosomatic index (HSI),viscerosomatic index (VSI) and lipid contents in liver and muscle increased with increasing dietary lipid level(P<0.05),but there was a trends for condition factor (CF) with first increased then decreased (P>0.05); (2)with increasing dietary lipid levels, the weight gain (WG) first increased, then decreased, and feed conversion ratio (FCR) decreased(P<0.05); (3)LPL gene was expressed in liver and muscle of GIFT tilapia,while the expression level in liver was significantly higher than that in muscle (P<0.05); (4) during the 48 h post-refeeding period,liver LPL activity in high-lipid group was significantly higher than that in low-lipid and middle-lipid group at 6 h,but significantly lower than that in low-lipid group at the 12 h,24 h and 48 h.There was a trend in low-lipid and middle-lipid group that liver LPL activity increased first and then decreased; (5) the expression of LPL was significantly higher in high-lipid group than that in low-lipid group (P<0.05); (6) there were a significant linear positive correlation between HSI,lipid contents in liver and muscle,and liver LPL expression in GIFT tilapia juvenile.The results indicated that LPL expression in GIFT tilapia was in a tissue specific pattern and liver was the main organ for secretion and expression of LPL; high dietary lipid level could inhibit growth of GIFT tilapia juvenile,decrease feed conversion ratio,induce the expression of LPL in liver,and promote fat deposition in liver and muscle; liver LPL expression was involved in fat deposition of GIFT tilapia juvenile.

    • Inhibition effect of Astragalus polysacharin on chemical hepatocyte damage of common carp (Cyprinus carpio)

      2014, 33(2):103-110. DOI: 1000-2421(2014)02-0103-08

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      Abstract:To evaluate the inhibition effect of Astragalus polysacharin (APS) on chemical hepatocyte injury of common carp,APS (0.2,0.4 and 0.8 mg/mL) was added to the primary hepatocytes pre-treatment,post-treatment and both pre- and post-treatment with the incubation of hepatocytes in the culture medium with 8 mmol/L CCl4.The morphology of liver cells was then observed by microscope,lactate dehydrogenase (LDH),glutamate pyruvate transaminase (GPT),glutamate oxalate transaminase (GOT),superoxide dismutase (SOD) and malondial-dehyde (MDA) in the supernatants were measured,hepatocyte viability was investigated and the mRNA expression of cytochrome P450 1A and 3A (CYP1A and CYP3A) in the hepatocytes were studied.The results showed that APS significantly improved cell viability,inhibited the elevation of GPT,GOT,LDH and MDA,and increased the SOD level in the supernatants (P<0.05 or P<0.01).The expression of CYP1A mRNA was improved in 0.4 and 0.8 mg/mL APS treatments (P<0.05) and the expression of CYP3A mRNA was upgraded in 0.4 mg/mL APS treatment (P<0.05).The observation of morphology also showed that APS effectively inhibited mortality of the hepatocytes.It can be concluded from the data obtained that APS exhibited protective effect against CCl4-induced hepatotoxicity in fish,and positively induced the expression of CYP1A and CYP3A.

    • >Food science and agricultural engineering
    • 20140220

      2014, 33(2):111-115. DOI: 1000-2421(2014)02-0111-05

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      Abstract:Based on the optimization for the test conditions,the influence of variety of tea plant,position of leaf,freshness and moisture content of fresh leaves on the dielectric properties were analyzed by LCR-bridge(HPS2816A).The results showed that the variety of tea plant had a significant impact on the capacitance and permittivity (P<0.05).With the decline in tenderness,the capacitance and permittivity increased significantly.The capacitance and permittivity showed a decreasing trend with the decline in the moisture content of fresh leaf,but with little change in the range of 0.7%-6.7%.Meanwhile,freshness had the similar influence on the capacitance and permittivity to the moisture content.In addition,the comparison on dielectric characteristic parameters among fresh leaves,pathological leaves,stalk and sundries (grass and leaf of camphor ) was also conducted.The result revealed that the capacitance and permittivity of pathological leaf,stalk and sundries in tea garden were significantly higher than those of fresh leaves (P<0.01).

    • Development of shape-fixing machine and optimization for shape fixation of needle-shaped famous green tea

      2014, 33(2):116-122. DOI: 1000-2421(2014)02-0116-07

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      Abstract:Shape-fixing machine was designed according to the theory of shape-fixing.Taking the 6CZG-60 shape-fixing machine as the experimental subject,orthogonal design experiment was conducted on three factors such as the water content (20%,25%,30%),temperature (40,50,60℃) and quantity (1.0,1.5,2.0 kg) of shape-fixing leaf.The results of single factor experiments showed that the water content and temperature of leaf had significant effect on the polyphenol and chlorophyll of tea.The leaf quantity had significant effect on the polyphenol,chlorophyll,amino acid and soluble sugar of tea.The time of shape-fixing significantly affects the polyphenol and soluble sugar of tea.Organoleptic analysis showed that the shape of tea was more tight and straight and the aroma was better,but the green degree of tea decreased with the decrease of water content of shape-fixing leaf.The procumbent and green degree of tea decreased with the increase of temperature.The color became darker especially when the temperature was more than 70℃.The result also revealed that the green degree,aroma and taste of tea decreased with the increase of leaf quantity.The straight and procumbent degree was better with the increase of time of shape-fixing.The orthogonal test showed that the best technology process parameters of 6CZG-60 shape-fixing machine were as follows:the water content of leaf is 20%,the quantity of leaf is 1.5 kg or so,the temperature of leaf is about 50℃ and the time is 15-20 minutes.

    • Studies on the osmotic characteristics of duck’s eggshell

      2014, 33(2):123-127. DOI: 1000-2421(2014)02-0123-05

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      Abstract:The duck eggshell is an important factor affecting the salting time and quality of the salted duck egg. For further mass transfer mechanism of Na+,Cl- in the process of pickled eggs, changes of duck’s eggshell mass transfer rate with curing liquid mass fraction of NaCl, temperature and time was researched. The experiment from single factor showed that effect of the mass fraction of NaCl in the pickling liquid on duck’s eggshell mass transfer rate is significant,the most appropriate value of NaCl mass fraction is critical saturation. In a certain range, effect of temperature on the mass transfer rate of duck’s eggshell is not significant. The structure characteristics of duck’s eggshell are important factors to influence the mass transfer rate in the summer and winter, the eggshell mass transfer rate with time was first increased and then decreased.

    • Design of hydraulic system of small multi-function chassis in hilly area

      2014, 33(2):128-132. DOI: 1000-2421(2014)02-0128-05

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      Abstract:A hydraulic system for small multi-function chassis was designed to be used in the hilly and mountainous regions of southwestern China after a full consideration of the characteristics of the terrain and the relay intercropping in this area. The selection of hydraulic components was determined by a theoretical calculation. A complete hydraulic drive system was adopted in the design to effectively reduce the size and weight,and to realize the stepless speed change and the pivot turn,which effectively solves the problem caused by the small space in the intercropping fields.Climbing experiments show that the machine can smoothly run through slopes less than 25°. All these prove that this machine can meet the basic requirement of walking operation in the southwest hilly areas.

    • >Literature summaries
    • Low molecular weight organic acids in soils and its environmental effects

      2014, 33(2):133-138. DOI: 1000-2421(2014)02-0133-06

      Abstract (1278) HTML (0) PDF 973.65 K (3123) Comment (0) Favorites

      Abstract:Low molecular weight organic acids(LMWOAs) are a kind of important active matters in soils.The sources and types of LMWOAs,and its environmental effects in soils are reviewed in this paper.The LMWOAs mainly originate from root exudates,decomposition of animal and plant,microbial synthesis and secretion,and the transformation of organic matters.The compositions of organic acids are extremely complicated but can be mainly classified into fatty and aroma families’ organic acids with less than 10 mmol/kg concentrations in soils.The LMWOAs play an important role in soil environmental processes.They could affect the movement,toxicity and bioavailability of heavy metals in soils,and influence the mobilization,transformation and degradation of organic pollutants.The mechanisms of LMWOAs on heavy metals and organic pollutants in soils are different.Some suggestions for further research in this field are proposed.

    • Application of algae as a resource in agricultural activities

      2014, 33(2):139-144. DOI: 1000-2421(2014)02-0139-06

      Abstract (1363) HTML (0) PDF 968.56 K (4415) Comment (0) Favorites

      Abstract:Algae are lower photosynthetic autotrophs which have close relationship with agricultural activities.With the deep understanding of physiological and ecological characteristics,algae have used more and more widelyin the practice of agricultural activities.This paper reviews the application of algaeas a resourcein agricultural activities including improvement of agricultural environment,utilized as food or food additives and health care products,as well as feed or bait.

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