Journal of Tea Science

Screening of the Beauveria bassiana Strain with High Virulence to Basilepta melanopus (Coleoptera: Chrysomeloidea)

WANG Dingfeng, LI Liangde, LI Jianlong, LI Huiling, ZHANG Hui, WANG Qingsen, WU Guangyuan

Journal of Tea Science. 2017, 37(3): 229-236.

Abstract ( 429 )

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The beetle (Basilepta melanopus) is one of the most serious leaf-feeding insects in tea garden, which seriously affects both tea yield and quality. In recent years, the beetle often caused serious damage in some tea gardens, especially organic tea gardens. How to effectively control this pest has become a serious problem. In order to screen high virulence strains of Beauveria bassiana to B. melanopus, 9 strains of B. bassiana isolated from the coleoptera pests in tea gardens were selected as candidates. In the preliminary screening, the biological characteristics of these 9 strains, including colony morphology, growth rate, sporulation, spore germination rate, thermotolerance and UV radiation resistance were detected. According to the above biological characteristics, three strains Bb338, Bb346 and Bb2-1 were selected for further bioassay against the adult of B. melanopus. Bioassay results showed that the strain Bb2-1 was the most virulent strain to the adults of B. melanopus, which had the highest corrected mortality rates of 100%, highest cadaver rates of 86.11% and shortest LT₅₀ of 3.32 d at a concentration of 1.0×10⁷ conidia per milliliter. The strain Bb2-1 has the best biological characteristics and the highest virulent against the adults of B. melanopus, which would play a very important role in biocontrol of B. melanopus.

Microscopic Observations of the Infection of Mycete in Raw Dark Tea

XU Wei, ZHAO Renliang, JIANG Yihe, WU Dan, ZHU Qi

Journal of Tea Science. 2017, 37(3): 237-242.

Abstract ( 301 )

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In this study, the process of mycete infection in raw dark tea under the condition of artificial mildew was observed by a combination of hematoxylin, eosin, aniline blue staining and scanning electron microscopy analysis. It was found that there was serious structural damages in mesophyll cells of raw dark tea. Under controlled temperature and humidity conditions, mycete spores were grown into mycelium on the surface of tea, crossed the damaged parts and the cavity structures and finally reached the whole leaves. These results provided a basis for understanding relative mechanism involved in mycete infection in raw dark tea.

Ultrasound-assisted Dispersive Liquid-liquid Microextraction Based on the Solidification of a Floating Organic Droplet Followed by Gas Chromatography for the Determination of Five Pyrethroid Pesticides in Tea Samples

GAO Yuling, GUO Xiujuan, QIAO Shi, SUN Peng

Journal of Tea Science. 2017, 37(3): 243-250.

Abstract ( 283 )

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A novel ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (UA-DLLME-SFO) which combined with gas chromatography coupled with ECD detector was developed for the determination of five pyrethroid pesticides (fenpropathrin, cyfluthrin, cyhalothrin, fenvalerate, deltamethrin) in tea. The optimal liquid-liquid microextraction experiment conditions were as follows: 20βμL hexadecane was used as extraction solvent. After ultrasound for 30 min under 35℃, 800βμL of acetone (disersive solvent) were rapidly transferred. The NaCl Mass Fraction was 4% and pH was adjusted to 4. The sample solution was then centrigugated at 10 000 r·min^-1 for 5 min under －3℃ and then injected for gas chromatography analysis. It was shown that a good linearity for these pyrethroids was obtained at concentrations of 1.0 to 150.0 μg·kg^-1 with correlation coefficients higher than 0.9994. The average recoveries of the 5 pesticides in liquid milk were in the range of 92.3% to 99.6% at spiked levels between 1 to 5 μg·kg^-1, with intra-day relative standard deviations lower than 3.5%（n=6）and inter-day relative standard deviations lower than 5.9% (n=3). The limits of detection and quantification were 0.11-0.24 μg·kg^-1 and 0.36-0.81 μg·kg^-1 , respectively. The proposed method is simple, fast, safe, reliable and applicable for analyzing pyrethroid pesticides in tea samples.

SNP Detection and Mapping of Theanine Synthetase Gene in Tea Plant

LI Xiaojie, MA Jianqiang, YAO Mingzhe, CHEN Liang

Journal of Tea Science. 2017, 37(3): 251-257.

Abstract ( 456 )

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The theanine synthetase (TS) gene is considered as the key functional gene for the synthesis of theanine in tea plant. In this study, an F₁ segregating population and its parents were used to detect single nucleotide polymorphism (SNP) in the TS gene for genetic mapping. According to the sequence alignment between the parents, three SNPs were found, and SNP735 was identified to be heterozygous in YS. SNP735 was subsequently transformed into dCAPS marker and used for genotyping in the F₁ population. The results showed that the segregation ratio of alleles at this SNP locus was close to 1:1. The dCAPS marker was mapped to LG03 at a position between TM299 and TM517 in the tea genetic map. Meanwhile, significant correlations between the dCAPS marker and the content of theanine and total amino acid were identified in this study.

Monitoring Black Tea Fermentation Using a Colorimetric Sensor Array-based Artificial Olfaction System

CHEN Lin, YE Yang, DONG Chunwang, HE Huafeng

Journal of Tea Science. 2017, 37(3): 258-265.

Abstract ( 511 )

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As the crucial procedure for production of black tea, fermentation plays an important role in quality control of black tea. This paper proposed a colorimetric sensor array-based artificial olfaction system to monitor black tea fermentation. Herein, a colorimetric sensor array by printing 16 chemical dyes including porphyrins/metalloporphyrins on a Silica gel thin-layer chromatography plate was utilized to detect volatile gases during black tea fermentation. Discrimination model was established by fisher discriminatory analysis and adaptive boosting algorithm based on BP-ANN (BP-Adaboost). Results showed that the discrimination rate and discrimination rate of cross-validation reached 100% and 90.74% respectively. BP-Adaboost model showed that the correlation coefficient of calibration set (Rc) and prediction set (Rp) were 0.9578 and 0.9132 respectively. This work demonstrates that it is feasible to distinguish the degree of black tea fermentation using a colorimetric sensor array-based artificial olfaction system.

Effects of Changeable Baking Techniques on Aroma Quality of Dangui Oolong Tea

SUN Jun, ZHU Liugang, LIN Zhikun, ZHANG Wenjing

Journal of Tea Science. 2017, 37(3): 266-272.

Abstract ( 384 )

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Orthogonal test of L₁₆(4⁵) was designed to study the effect of changeable baking temperature on aroma quality and components of Dangui Oolong tea in southern Fujian. Results showed that treatment of A₄B₁C₄D₂E₃got teas with high aroma quality. Results also showed that baking process of Dangui Oolong tea could be divided in three steps, with the optimal process of 120℃-20βmin, 90℃-130βmin, 120℃-30βmin. Totally 64 kinds of aroma components were identified, including alcohols, aldehydes, nitrogenous compounds, hydrocarbons. The main components were trans-nerolidol, alpha-farnesene, benzeneacetaldehyde, indole, phenylethyl alcohol, phenylethyl-2-methylbutanoate, benzyl nitrile, dihydrolinalool, benzyl alcohol, linalool and styrene, which totally accounted for nearly 90%. The main factors influencing aroma quality of Dangui Oolong tea were baking temperature and time in the third step, followed by the first and the second steps. High temperature could improve tea aroma. These findings laid the foundation for further researches on baking technology of Dangui Oolong tea.

A Sensing PVC Membrane Based on Fluorescence Enhancement of Erythromycin A for Lead (Ⅱ) Detection in FU Tea

LONG Liping, MENG Wei, WANG Jiaoliang, XIE Dan, HE Guowen, XIAO Guqing

Journal of Tea Science. 2017, 37(3): 273-279.

Abstract ( 378 )

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An optical chemical sensing membrane based on reversible fluorescence enhancement of Erythromycin A immobilized in a plasticized poly (vinyl chloride) (PVC) membrane for Lead (Ⅱ) detection was developed. The membrane of the sensor consists of 50 mg of PVC, 100 mg of Di (2-ethylhexyl) phthalate and 2.94 mg of Erythromycin A. The maximum response of the sensing membrane to Lead (Ⅱ) was obtained in Tris/HCl buffer solution ( pH 8.0). Under optimal conditions, the proposed sensor responded linearly to Lead (Ⅱ) in the range of 4.00-6.00 mmol/L and had a detection limit of 0.10 μmol·L^-1. The response time of the sensor was less than 50 s. In addition to the high reproducibility and reversibility of the fluorescence signal, the sensor also exhibited good selectivity. Except for Cr₂O₇^2-and MnO₄^-, it was not interfered by other common metal ions and anions. It was applied for the determination of Lead(Ⅱ) in a sample of FU Tea, which offered a satisfactory result.

Study on Parameter Optimization of Centrifugal and Continuous Dewatering of Tea Leaves Based on Numerical Simulation of Multiphase Flow

ZHU Zhinan, ZHAO Zhangfeng, ZHONG Jiang, ZHOU Rengui, ZHANG Xian

Journal of Tea Science. 2017, 37(3): 280-289.

Abstract ( 377 )

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In order to improve the dewatering rate and achieve continuous dewatering, a concept of increasing the dispersion of tea leaves through venting, and using the multiphase flow coupling technology of discrete field - flow field was introduced based on the centrifugal dewatering principle. The centrifugal dewatering process of fresh tea leaves was numerically simulated and verified by experiments to determine the factors affecting the dewatering rate. It was found that the difference of rotational speeds between centrifugal barrel and spiral body had the greatest influence on the dewatering effect in the case that the direction of blowing air was outward from the centrifugal barrel. The centrifugal speed ranked the second on the dewatering effect. The speed of wind had the least effect on the dewatering effect.

Research on the Protective Effects of TFDG on IL-1β-induced Inflammatory Injury in Rat Chondrocytes in Vitro

ZHOU Ying, HUANG Qian, ZHANG Tian, CHEN Ping

Journal of Tea Science. 2017, 37(3): 290-298.

Abstract ( 411 )

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The chondrocytes were isolated and harvested from knee articular surface of male Sprague-Dawley rats, which were identified by toluidine blue and type II collagen immunofluorescence staining. To investigate potential protective effects of theaflavin-3,3′-digallate (TFDG) on IL-1β-induced inflammatory injury in rat chondrocytes in vitro, a model of osteoarthritis was established through stimulating rat chondrocytes with IL-1β. Inverted phase contrast microscopy showed TFDG treatment significantly improved osteoarthritis chondrocytes morphology. Real-time PCR results showed that TFDG treatment not only up-regulated chondrocyte marker Col II mRNA expression, but also down-regulated pro-inflammatory cytokines IL-1β and IL-6 mRNA expression. ELISA analysis further confirmed TFDG treatment significantly decreased the secretion of inflammatory factors. Western blot results showed that TFDG treatment significantly inhibited the inflammation-related enzyme COX-2 expression. Taken together, these results indicate that TFDG has a preventive effect on IL-1β-induced inflammatory injury in rat chondrocytes in vitro by reducing inflammatory reaction.

Effects of Three Amendments on Selenium Availability of Highly Acidic and Se-rich Soil in Tea Garden and their Relative Mechanisms

XIE Shanni, ZONG Lianggang, ZHANG Qihui, DAI Rongbo, PAN Hanyue, YUAN Qiang

Journal of Tea Science. 2017, 37(3): 299-307.

Abstract ( 416 )

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A series of incubation experiment and field trail were carried out to study the effects and mechanisms of three amendments (straw charcoal, calcium-magnesium phosphate and earthworm liquid fertilizer) and their different applying modes on selenium (Se) availability of highly acidic and Se-rich soil in tea gardens. The results of incubation experiment showed that all treatments increased soil pH and the contents of available Se, but decreased the contents of exchangeable aluminum (Al) significantly. Se was transformed from organic bound form to soluble form, and Al was transformed from exchangeable form to organic complexed form by morphological analysis. The results of field trail showed that different applying modes effectively inhibited further soil acidification, enhanced the availability of Se and increased the Se content in tea leaves simultaneously. A combined application of straw charcoal, calcium-magnesium phosphate and earthworm liquid fertilizer showed the highest effects. The results of this research provide reference to develop Se-enriched tea in acidic and selenium-rich area.

An Empirical Study on the Impact Factors of Adoption of Green Prevention and Control Technology by Tea-growers

HU Linying, DU Pei, CHEN Fuqiao, JIANG Aiqin, JIANG Renhua, LU Chengyin

Journal of Tea Science. 2017, 37(3): 308-314.

Abstract ( 421 )

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Survey data were collected from 2β210 tea-growers from sixteen major tea producing provinces and then the Logit model was established to analyze the imfact factors of Green Prevention and Control Technology (GPCT) adoption by tea-growers. The results showed that GPCT adoption by tea-growers was affected by personality variables, family characteristics, operating characteristics of tea plantation, organizational and technical service characteristics. The most effective factor was organizational and technical service characteristics. Concretely, the farmer’s age, household size, cultivated area had significantly negative effects on technology adoption. The knowledge of the pesticide residues’ limitation standard (PRLS), household income, the connection with cooperation, pest control training frequency and communication with others had positive effects on technology adoption. The technology adoption rate of tea-growers who knew the PRLS was about 2 times higher than the rest. An increase of household income by ten thousand yuan could increase the technology adoption rate by 2%. Cooperative members’ technology adoption rate was 1.73 times higher than non-members. Every training of farmers could promote technology adoption rate by 1.50 times. However, the farmers’ educational status, non-agricultural income didn’t significantly affect their choices. Therefore, the related government department should improve farmers’ organization, increase training times and cut down the cost of technology adoption to promote GPCT adoption to achieve green agriculture.

Study on the Tea Farmers′ Cognition and Participation Model to Tea Manor——Based on the Survey Data of Fujian Province

SU Baocai, LI Yuxuan, GONG Peng

Journal of Tea Science. 2017, 37(3): 315-323.

Abstract ( 382 )

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Tea Manor is the new mode of production and operation during tea industrial upgrading, and its popularization and improvement are largely dependent on the participation of farmers. In this paper, the willingness and behavior of farmers to participate in the production of tea manor from three dimensions: individual characteristics, social and economic characteristics and the functional cognition of tea manor were discussed by surveying 438 farmers in Fujian province. At the same time, the farmers′ cognition of the management model of tea manor and the theoretical framework for participation were constructed. The results showed that the age of tea farmers, income, tea revenue compared with expectations, tea manor brand, tea tourism cognition had significantly positive effects on their participation in tea manor. However, the production of tea manor to attract young people to return and start business, and the adoption of new technologies had no significant effect. Therefore, improving the service functions of local government and farmers′ cognition on tea manor are important for the development of tea manor. The government should increase the financial subsidies for farmers′ participation and breed model household of tea manors.

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