我国茶园施肥现状与减施潜力分析

【目的】茶树是我国重要的经济作物之一,合理施肥是保证茶叶高产优质的重要措施,受茶树品种、采摘模式、栽培水平的影响,我国不同地区茶园间施肥量存在较大的差异。厘清我国茶园施肥现状,分析不同茶区施肥水平的差异,寻求差异化的减肥途径,对实现我国茶园化肥减施增效,促进茶产业可持续发展具有重要意义。【方法】依托国家茶产业技术体系试验站,本研究于2010—2014年期间在我国主要茶区调查了5000多个茶树种植单元,约占我国茶园总面积的5%。调查内容包括氮磷钾肥料品种、用量、施用时间、施用方式以及茶园面积、茶树品种、施肥成本等信息。根据肥料养分含量计算不同种植单元的氮磷钾养分投入量,有机养分替代比例,并以现行的茶园推荐施肥标准作为施肥评价依据,对不同区域茶园的施肥水平进行了评价。【结果】我国茶园的养分投入总量 (N + P₂O₅ + K₂O) 为796 kg/hm2,施用有机肥的茶园样本比例为46%,按纯养分计,茶园有机养分投入量平均占总养分投入量的15%。各省茶区年均养分投入量为N 281～745 kg/hm2、P₂O₅ 72～485 kg/hm2、K₂O 76～961 kg/hm2。参照目前的推荐肥料用量,我国有30%左右茶园存在化肥过量施用问题,其中山东、湖北、湖南、江西、四川、福建等地过量施肥问题较为突出。复合肥已成为茶园的重要肥料品种,80%的茶园施用的是等养分比例的复合肥,茶园中磷肥或者钾肥过量施用现象开始凸显,福建、江西、湖南等地过半茶园磷、钾养分投入过量。根据过量施肥茶园的现有施肥水平,通过总量控制和增加有机肥比例等途径,大约可削减30%～40%的化肥用量。【结论】我国30%的茶园化肥过量施用,80%的茶园施用的化肥氮磷钾比例不完全符合茶叶养分需求,有机肥养分所占比例偏低,只有15%。依据不同茶区养分具体管理方式、茶叶栽培特点以及土壤条件,因地制宜采取差异化的茶园化肥减施策略,大约可削减30%～40%的化肥用量。     

Analysis of agricultural residues on tea using d-SPE sample preparation with GC-NCI-MS and UHPLC-MS/MS

This study presents new sample preparation and analytical procedures for the quantification of pesticides on processed tea leaves. The new method includes tea extraction and dispersive solid phase extraction (d-SPE) to prepare gas chromatography (GC) and ultrahigh-performance liquid chromatography (UHPLC)-ready samples, providing a fast and cost-effective solution for time-sensitive industrial analysis to fulfill regulatory requirements. Both GC-negative chemical ionization mass spectrometry (GC-NCI-MS) and UHPLC-tandem mass spectrometry (UHPLC-MS/MS) were employed to produce highly sensitive and reproducible data. Excellent limits of detection (typically below 1 μg/kg for GC and 10 μg/kg for UHPLC), wide linearity ranges, and good recoveries (mostly >70%) were achieved on the selected pesticides. Twenty-seven tea samples purchased from local grocery stores were analyzed using the newly developed methods. Among the pesticides analyzed, endosulfan sulfate and kelthane were the most frequently detected by GC-NCI-MS and imidacloprid and acetamiprid by UHPLC-MS/MS in these teas. The samples were found to be relatively clean, with <1 mg/kg of total pesticide residues. The organic-labeled teas were significantly cleaner than nonorganic ones. The cost per gram of tea did not correlate with pesticide residue levels detected.     

北京郊区有机蔬菜土壤养分平衡及δ^15N特征分析

本研究针对北京郊区汇源与正谷有机蔬菜基地,通过对不同蔬菜生产基地取样分析,研究有机和常规蔬菜生产条件下土壤养分平衡特征,分析有机生产蔬菜和土壤的15N特征。结果表明,（1）有机蔬菜生产与常规生产对比,由于施肥数量不同,汇源有机蔬菜基地土壤N、P及K盈余量（分别为356～472kg·hm-2、298kg·hm-2和200～226kg·hm-2）高于当地常规生产,而正谷有机蔬菜生产土壤N、P及K养分盈余量（分别为-164～190kg·hm-2、107.9～435.5kg·hm-2和-164.5～-136.8kg·hm-2）低于当地常规生产;（2）汇源有机蔬菜生产模式中,土壤N素养分有逐季累积的趋势,有机肥的N、P和K养分存在着不平衡性,这可能是造成0～20cm土层磷素大量累积的重要原因;（3）蔬菜类别不同,δ15N值不同,一般为叶菜类最高（10.49‰）,果菜类次之（10.07‰）,根菜类δ15N值最低（5.62‰）;（4）植物不同部位δ15N值也有差异。针对圆椒的分析表明,圆椒叶δ15N（12.44‰）〉圆椒果实δ15N（9.35‰）;（5）土壤δ15N与土壤全N之间有一定的相关性,回归方程为δ15N土壤=13.098N土壤＋3.7624,R2=0.938,而植物δ15N与土壤δ15N之间、植物δ15N与土壤全氮相关性较差。长期施用有机肥,使得土壤中15N更多来自有机肥,进而表现为蔬菜δ15N升高,高量有机肥可以短期内增加叶菜类植物δ15N值。     

Radical scavenging conserves from unused fresh green tea leaves

Green teas were made by inactivating the enzymes present in fresh leaves of coarse/pruned (unused) and normal (used for tea) grades using different sources of thermal energies. Green teas were extracted in a Soxhlet using different solvents. The obtained miscella was subjected to concentration to give the extract. The extract was subjected to solvent-solvent extraction. Solvent extract was concentrated to obtain conserve. The yields of conserves are 17 +/- 0.8 and 15 +/- 0.8% from green teas of normal and coarse tea leaves, respectively. The radical scavenging activity of these extracts was evaluated using a DPPH in vitro model system. The total polyphenol content was also determined and found to be higher in conserves from normal tea leaves. However, radical scavenging activity of conserves from coarse and normal green tea leaves was found to be >90% at 15 ppm concentration. The HPLC profiles of these conserves were used to quantify the total catechin content with the help of calibration curves prepared using authentic samples at known concentrations. The total catechin content is found to be in the range of 55-85%. Results indicated that the extracts from coarse leaves also possess potential biological activity and could be used as nutraceuticals as well as for preservation purposes in food formulations.     

Structure-activity relationships of tea compounds against human cancer cells

The content of the biologically active amino acid theanine in 15 commercial black, green, specialty, and herbal tea leaves was determined as the 2,4-dinitrophenyltheanine derivative (DNP-theanine) by a validated HPLC method. To define relative anticarcinogenic potencies of tea compounds and teas, nine green tea catechins, three black tea theaflavins, and theanine as well as aqueous and 80% ethanol/water extracts of the same tea leaves were evaluated for their ability to induce cell death in human cancer and normal cells using a tetrazolium microculture (MTT) assay. Compared to untreated controls, most catechins, theaflavins, theanine, and all tea extracts reduced the numbers of the following human cancer cell lines: breast (MCF-7), colon (HT-29), hepatoma (liver) (HepG2), and prostate (PC-3) as well as normal human liver cells (Chang). The growth of normal human lung (HEL299) cells was not inhibited. The destruction of cancer cells was also observed visually by reverse phase microscopy. Statistical analysis of the data showed that (a) the anticarcinogenic effects of tea compounds and of tea leaf extracts varied widely and were concentration dependent over the ranges from 50 to 400 microg/mL of tea compound and from 50 to 400 microg/g of tea solids; (b) the different cancer cells varied in their susceptibilities to destruction; (c) 80% ethanol/water extracts with higher levels of flavonoids determined by HPLC were in most cases more active than the corresponding water extracts; and (d) flavonoid levels of the teas did not directly correlate with anticarcinogenic activities. The findings extend related observations on the anticarcinogenic potential of tea ingredients and suggest that consumers may benefit more by drinking both green and black teas.     

茶树对可溶性有机和无机态氮的吸收与运转特性

【目的】 揭示亚热带茶树能否直接吸收利用分子态可溶性有机氮,探讨茶树吸收可溶性有机和无机氮后的运转特性差异。【方法】 采用13C、15N双标记甘氨酸、15N标记硫酸铵和15N标记硝酸钾为同位素示踪剂,采用茶树（黄金桂）幼苗为试验材料进行同位素示踪盆栽试验,用同位素质谱仪测定茶树植株地上和地下部的13C、15N丰度。【结果】 供试土壤施用13C、15N双标记甘氨酸态有机氮后,2 h和6 h茶苗地下部和整株中的13C增量/15N增量比值均接近于1:1的理论值;2 h和6 h茶苗地上部未检出13C增量,而72 h地上部13C增量达0.284 μmol/（g,DW）;施用铵态氮2 h、6 h和72 h茶苗地下部、地上部和整株中的15N增量均极显著高于施用硝态氮和甘氨酸态有机氮;施用铵态氮6 h茶苗地上部15N增量/地下部15N增量比率分别比硝态氮和甘氨酸态有机氮的比率高34.7%和65.0%,72 h茶苗地上部15N增量/地下15N增量比率分别比硝态氮和甘氨酸态有机氮的比率高88.6%和133.0%,差异均达极显著水平。【结论】 黄金桂茶苗具有从土壤中直接吸收利用甘氨酸分子态有机氮的能力,但吸收量不及铵态氮和硝态氮;吸收的可溶性分子态有机氮可以从茶树根系运转至地上部;不同形态氮素在茶树植株体内的迁移能力高低表现为:铵态氮>硝态氮>甘氨酸态氮,该研究结果进一步证明陆地生态系统植物直接吸收利用可溶性有机氮是普遍存在的现象。     

Factors affecting the levels of tea polyphenols and caffeine in tea leaves

An isocratic HPLC procedure was developed for the simultaneous determination of caffeine and six catechins in tea samples. When 31 commercial teas extracted by boiling water or 75% ethanol were analyzed by HPLC, the levels of (-)-epigallocatechin 3-gallate (EGCG), and total catechins in teas were in the order green tea (old leaves) > green tea (young leaves) and oolong tea > black tea and pu-erh tea. Tea samples extracted by 75% ethanol could yield higher levels of EGCG and total catechins. The contents of caffeine and catechins also have been measured in fresh tea leaves from the Tea Experiment Station in Wen-Shan or Taitung; the old tea leaves contain less caffeine but more EGCG and total catechins than young ones. To compare caffeine and catechins in the same tea but manufactured by different fermentation processes, the level of caffeine in different manufactured teas was in the order black tea > oolong tea > green tea > fresh tea leaf, but the levels of EGCG and total catechins were in the order green tea > oolong tea > fresh tea leaf > black tea. In addition, six commercial tea extracts were used to test the biological functions including hydroxyl radical scavenging, nitric oxide suppressing, and apoptotic effects. The pu-erh tea extracts protected the plasmid DNA from damage by the Fenton reaction as well as the control at a concentration of 100 microg/mL. The nitric oxide suppressing effect of tea extracts was in the order pu-erh tea >/= black tea > green tea > oolong tea. The induction of apoptosis by tea extract has been demonstrated by DNA fragmentation ladder and flow cytometry. It appeared that the ability of tea extracts to induce HL-60 cells apoptosis was in the order green tea > oolong > black tea > pu-erh tea. All tea extracts extracted by 75% ethanol have stronger biological functions than those extracted by boiling water.     

The feasibility of using delta15N and delta13C values for discriminating between conventionally and organically fertilized pepper (Capsicum annuum L.)

A greenhouse experiment was conducted to determine the feasibility of using leaf and fruit delta15N and delta13C values to discriminate between conventionally and organically fertilized peppers, when conventional management involves the application of organic amendment for soil preparation. All of the treatments involved adding horse manure to the soil before applying different rates of synthetic N fertilizers: 0 (T1 and T2), 150 (T3), and 300 kg ha(-1) (T4). The difference between T1 and T2 was that no synthetic fertilizer had been applied to plot T1 during the 5 years prior to the experiment. Significant differences were found in the delta15N values of leaves and fruit from the plants grown under organic or mixed fertilization. The results indicate the possibility of using 15N natural abundance as an indicator of fertilization management. On the other hand, delta13C values did not contribute any additional information for discriminating between the organically and the synthetically and organically fertilized peppers.     

Patterns of natural N in soils and plants from chemically and organically fertilized uplands

Diagnostic tests for organic production of crops would be useful. In this study, the difference in natural ¹⁵N abundances (δ¹⁵N) of soils and plants between fertilizer-applied upland (FU) and compost-applied upland (CU) fields was investigated to study using δ¹⁵N as a marker of organic produce. Twenty samples each of soils and plants were collected from each field in early summer after applying fertilizer or compost. The δ¹⁵N of fertilizers and composts was −1.6±1.5‰ (n=8) and 17.4±1.2‰ (n=10), respectively. The δ¹⁵N of total soil-N was significantly (P<0.05) higher in CU fields (8.8±2.0‰) than in FU fields (5.9±0.7‰) due to long-term continuous application of ¹⁵N-enriched compost, as indicated by a positive correlation (r=0.62) between N content and δ¹⁵N of total soil-N. The NO₃⁻ pool of CU soils (11.6±4.5‰) was also significantly (P<0.05) enriched in ¹⁵N compared to FU soils (4.7±1.1‰), while the ¹⁵N contents of NH₄⁺ pool were not different between both soils. Compost application resulted in ¹⁵N enrichment of plants; the δ¹⁵N values were 14.6±3.3‰ for CU and 4.1±1.7‰ for FU fields. These results showed that long-term application of compost resulted in a significant ¹⁵N-enrichment of soils and plants relative to fertilizer. Therefore, this study suggested that δ¹⁵N could serve as promising indicators of organic fertilizers application when used with other independent evidence. However, further studies under many conditions should be conducted to prepare reliable δ¹⁵N guidelines for organic produce, since the δ¹⁵N of inorganic soil-N and plant-N are influenced by various factors such as soil type, plant species, the rate of N application, and processes such as mineralization, nitrification, and denitrifcation.     

Profiles of purine and pyrimidine nucleotides in fresh and manufactured tea leaves

Profiles of nucleotide levels in two varieties of Japanese green teas (cv. Yabukita and Saemidori), a Chinese green tea (Longjing), and two Japanese black teas (cv. Benifuuki and Benihikari) were determined and compared with that of fresh tea leaves. The concentration of 5'-nucleotides in green tea was much higher than in black tea. Nucleoside diphosphates were present in larger amounts than nucleoside triphosphates in manufactured green and black teas, whereas the triphosphates predominated in fresh tea leaves. Low levels of 3'-nucleotides were found in green and black teas. Inosine 5'-monophosphate, which is utilized as a seasoning component, was found in all manufactured teas in concentrations ranging from 50 to 200 nmol/g of dry weight. The levels of both inosine 5'-monophosphate and guanosine 5'-monophosphate were high in Chinese Longjing green tea. The unique profiles of nucleotides in manufactured teas may be a consequence of the action of degradation enzymes, such as ribonuclease, apyrase, phosphatase, nucleotidase, and adenosine 5'-monophsphate deaminase during the commercial processing of the young leaves.     

Capillary electrophoretic determination of theanine, caffeine, and catechins in fresh tea leaves and oolong tea and their effects on rat neurosphere adhesion and migration

Theanine, caffeine, and catechins in fresh tea leaves and oolong tea were determined by using capillary electrophoresis (CE). CE separated these tea polyphenols from three other tea ingredients, namely, caffeine, theophylline, and theanine, within 8 min. The young leaves (apical bud and the two youngest leaves) were found to be richer in caffeine, (-)-epigallocatechin gallate (EGCg), and (-)-epicatechin gallate (ECg) than old leaves (from 5th to 7th leaves). On the other hand, the old leaves (from 8th to 10th leaves) contained higher levels of theanine, (-)-epigallocatechin (EGC), and (-)-epicatechin (EC). Results from a comparison of fresh young tea and oolong tea compositions indicated oolong tea contained more theanine and catechins than fresh young tea. Furthermore, it was found that the levels of theanine, EGC, and EGCg in young leaves rose markedly with the withering process. Caffeine did not markedly change. However, fully or partially fermented teas (oolong tea or pauchong tea) have a common initial step in the withering process. Fresh tea leaves or oolong tea extract (0.1%, w/v) markedly inhibited neurosphere adhesion, cell migration, and neurite outgrowth in rat neurospheres. Theanine (348 micrograms/mL) and caffeine at high concentration (50 micrograms/mL) did not inhibit neurosphere adhesion or migration activities, but EGCg at 20 micrograms/mL effectively inhibited neurosphere adhesion for 24 h. These results indicated that EGCg might affect neural stem cell survival or differentiation.     

Effect of microbial fermentation on caffeine content of tea leaves

Caffeine is widely used in the food and pharmaceutical industries. For safety concerns, natural caffeine is preferred over synthetic products despite of its high cost. To explore more economical methods of acquiring natural caffeine, we adopted a microbial fermentation technique to increase the caffeine content of tea leaves. Our studies showed that the caffeine content in tea leaves increased reasonably after treating leaves with microorganisms for a period of time (i.e. orthodox pile-fermentation), and the amount of caffeine content increase varied significantly between black and green teas (27.57% and 86.41%). These results suggested that the change of caffeine content in tea leaves during the pile-fermentation depended not only on the growth and reproduction of microorganisms, but also on the tea composition.     

我国有机茶稳定同位素特征与δ15N标识相关性研究

为探明我国有机茶稳定同位素分布情况及δ¹⁵N标识的相关因素,本研究收集了全国不同地区申请有机茶认证企业的145个样品,采用元素分析-稳定同位素比率质谱仪测定稳定同位素比率(δ¹³C、δ¹⁵N、δ²H、δ¹⁸O),结合单因素方差分析和正态分布模型探究稳定同位素特征分布规律。结果表明,有机茶样品δ¹³C分布于-31.0‰ ~ -23.7‰之间,不同产地间差异不显著。δ²H和δ¹⁸O范围分别为-107.1‰ ~ -24.8‰和17.2‰ ~ 32.0‰,均存在显著地域差异。我国有机茶δ¹⁵N正态分布范围为-4.6‰ ~ 7.0‰,平均值为1.2‰。其中有机茶生产面积大的地区样品δ¹⁵N范围为1.6‰ ~ 5.8‰,显著高于生产面积小的地区(-2.5‰ ~ 0.4‰,P<0.01),表明δ¹⁵N指标作为有机茶标识特征与产区生产面积之间存在一定的相关性。本研究为基于稳定同位素技术的有机茶真伪鉴别提供了研究基础,为有机茶的认证与监管提供了一定的理论依据。     

施肥对土壤及黄瓜中稳定性氮同位素丰度的影响

研究不同肥料配施对土壤、黄瓜及其叶片中稳定性氮同位素丰度(1δ5N‰)及硝酸盐和硝酸还原酶活性的影响。结果表明,随着配施有机肥比例的降低,黄瓜中1δ5N呈现先低后高再低的趋势;各处理单施化肥初期时黄瓜中1δ5N与有机肥60%和40%配施处理间差异显著(P0.05),中期时与有机肥60%、40%配施处理及对照间的差异显著(P0.05),末期时与有机肥60%配施处理间有差异(P0.05),与其他不同配施时差异不显著(P0.05);相同处理的不同采摘时期黄瓜中1δ5N差异不显著(P0.05)。不同处理时叶片与黄瓜间的1δ5N呈正相关(r=0.9836),其1δ5N主要受不同肥料配施处理的影响。随着有机肥比例的降低,黄瓜中硝酸盐含量逐渐降低,与黄瓜中1δ5N间的线性相关性差(r=0.6568);而叶片中硝酸还原酶活性逐渐提高,其中对照处理、100%、80%和60%有机肥处理时与叶片中δ15N丰度呈正相关(r=0.9187);60%、40%、20%有机肥和100%化肥处理时与叶片中1δ5N呈负相关(r=-0.9773)。总体来看,可以初步利用1δ5N作为标记来区分有机肥和化肥种植的黄瓜,但需要进一步研究1δ5N在作物中的分馏和分布规律。     

Characterization and phenanthrene sorption of tea leaf powders

The sorption of hydrophobic organic compounds by natural organic matter is mainly regulated by its aromatic and aliphatic fractions, but it is not clear which fraction is more dominant. In this study, six types of Chinese tea leaves (three varieties of tender and three corresponding mature leaves) and their respective brewed ones were analyzed by elemental analysis, 13C NMR, and Fourier transform infrared attenuated total reflectance. Their sorption of phenanthrene was examined using a batch equilibration technique. The aromatic carbon content of tea leaves reduced while the aliphatic carbon content increased with increasing maturity and brewing. Sorption isotherms by all of the 12 tea sorbents were practically linear, showing a partition type sorption. The phenanthrene KOC (organic carbon-normalized sorption capacity) of the 12 sorbents ranged from 6960 to 32,900 mL/g, which increased with increasing aliphatic carbons and decreasing aromatic carbons in the tea leaves. The dissolved organic matter was released into solution from the sorbents during the sorption process, which could bind phenanthrene in the solution, and thereafter leading to underestimation of sorption capacity of the sorbents, but this did not change the correlation trends between KOC and functional carbon group content. Aliphatic fractions rather than aromatic moieties regulated the phenanthrene sorption of the tea leaf powders used in this study.     

不同氮肥处理对土壤和番茄中稳定性氮同位素丰度的影响

采用盆栽番茄的方式,根据氮肥类型和施用量,设置8种肥料处理（以纯氮计）：C1（有机肥,9.5g）、CU1（有机肥、化肥均为4.75g）、U1（化肥,9.5g）、C2（有机肥,19g）、CU2（有机肥、化肥均为9.5g）、U2（化肥,19g）、C3（有机肥,29g）、CK（不施肥料）,分析各处理的土壤、番茄叶片和果实δ15N的变化,比较不同部位δ15N的差异.结果表明,（1）施用有机肥能显著提高土壤、叶片和果实的δ15N（P ＜0.05）,而施用化肥则显著降低其δ15N（P＜0.05）.纯有机肥（C1、C2、C3）处理番茄叶片和果实δ15N分别为6.02‰ ～ 12.75‰和4.69‰～8.24‰,纯化肥（U1、U2）处理为2.83‰～5.53‰和2.66‰ ～4.50‰,纯有机肥处理δ15N显著高于纯化肥处理.（2）番茄植株不同部位δ15N的比较结果为老叶＞新叶＞新茎＞果实＞老茎＞侧根＞主根,表明氮素由根部吸收经过茎的运输到达叶片和果实的过程中,15N逐步富集.（3）建议将利用氮稳定同位素技术鉴别番茄果实纯有机肥和纯化肥处理的δ15N的阈值设定为5‰,有机种植检测可以借鉴此法设定相应的临界值,以鉴别有机种植和非有机种植.研究结果表明通过氮稳定同位素技术可以区分植物中氮素的来源,从而得知作物生长过程中的施肥情况,为有机食品检测提供有效方法.     

Determination of tea polyphenols and caffeine in tea flowers (Camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects

The native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin 3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed by an isocratic HPLC procedure. The levels of total catechins and caffeine were determined in tea flowers collected from 10 different species of Camellia sinensis. The results showed the levels of total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g. Levels of catechins and caffeine in tea leaves and various teas were also determined and ranged from 2 to 126 mg/g and from 23 to 49 mg/g, respectively. Both tea flower and tea leaf extracts exert their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells. Most tea flowers contain less caffeine, but comparable amounts of total catechins, compared to tea leaves and teas. The present study demonstrates that both tea flowers and tea leaves contain appreciable amounts of catechins and caffeine. It is likely that tea flowers might be useful for making alternative tea beverages.     

Natural 15N and 13C abundance in Andisols influenced by long-term fertilization management in Japan

Two field experiments were conducted on Andisols in Japan to evaluate the changes in the natural ¹⁵N and ¹³C abundance in the soil profile and to determine whether the values of δ¹⁵N could be used as an indicator of fertilizer sources or fertilizer fate. The 6-year experiment conducted at the National Agricultural Research Center (NARC) consisted of the following treatments: application of swine compost (COMPOST), slow-release nitrogen fertilizer (SRNF), readily available nitrogen fertilizer (RANF), and absence of fertilization (CONTROL). Experimental plots located at the Nippon Agricultural Research Institute (NARI) received cattle compost at different rates for 12 years; a forest soil at this site was sampled for comparison. Swine compost application led to a considerable change in the δ¹⁵N distribution pattern in the soil profile, with the highest δ¹⁵N values recorded in the top 20 cm layers of the COMPOST plot, decreasing in the sequence of CONTROL >- RANF > SRNF, mainly due to the relatively high δ¹⁵N value of swine compost and its subsequent decomposition. In contrast, SRNF application resulted in the lowest δ¹⁵N values in soil, indicating the presence of negligible nitrogen losses relative to input and low nitrogen cycling rates. Values of δ¹⁵N increased with compost application rates at NARI. In the leachate collected at 1-m depth, the δ¹⁵N values decreased in the sequence of COMPOST > RANF ≥ CONTROL > SRNF. The δ¹³C values in soil peaked in the 40–60 cm layers for all the fertilizers. The δ¹³C value was lowest in forest soil due to the presence of plant residues in soil organic matter. These results indicated that the δ¹⁵N values in the upper soil layers or leachate may enable to detect pollution sources of organic or inorganic nitrogen qualitatively in Andisols.     

施氮对茶园土壤氟和茶树新梢氟含量的影响

通过田间试验研究了不施肥(CK)、施氮360 kg?hm?2(T1)、施氮720 kg?hm?2(T2)处理下茶园土壤无机氮、p H、各形态氟含量的动态变化和春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,探讨茶园施氮对土壤和茶树新梢氟含量的影响。结果表明:1)茶园施氮后短期内(20~30 d)土壤水溶态氟含量显著降低,土壤交换态氟和铁锰结合态氟含量降低;长期(45~50 d)土壤水溶态氟含量的降低作用减弱,土壤交换态氟和铁锰结合态的含量增加;在试验结束时(164 d),与CK处理相比,T1处理0~20 cm土壤各形态氟含量降低,T2处理0~20 cm土壤各形态氟含量增加。2)0~20 cm茶园土壤水溶态氟、铁锰结合态氟与NH4+-N分别呈极显著负、正相关(P0.01),20~40 cm土壤水溶态氟、交换态氟与NO3?-N分别呈极显著正、负相关(P0.01)。土壤p H与土壤水溶态氟含量极显著负相关(P0.01),与其他3种形态氟含量相关性不显著。土壤铁锰结合态氟与交换态氟、有机结合态氟呈显著、极显著正相关,但与土壤水溶态氟均无显著相关性。3)春茶前后施氮可以降低春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,但未达显著水平。T1处理新梢氟含量的降低值为夏茶(25.15~27.95 mg?kg?1)秋茶(21.06~24.31 mg?kg?1)春茶(18.58~21.03 mg?kg?1),T2处理的降低值为秋茶(18.64~22.34 mg?kg?1)夏茶(7.79~14.14 mg?kg?1)春茶(3.52~7.30 mg?kg?1)。春、夏、秋茶树新梢氟含量主要受0~20 cm土壤无机氮和20~40 cm土壤p H的影响。因此推测施氮通过影响茶树根系氟的吸收和氟在叶片中的累积过程调控茶树新梢氟含量,该研究成果为合理利用施氮技术降低茶园土壤和茶树新梢氟含量提供了理论依据。     

氮磷钾对春茶光合生理及氨基酸组分的影响

【目的】当前为追求茶园高产盲目施肥、滥用化肥造成生态环境破坏的现象较为严重,因此如何合理施肥显得尤为重要,本文通过研究氮、磷、钾不同水平及其配比对春茶净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)和水分利用效率(WUE)等光合生理指标和春茶新梢氮、磷、钾含量,氨基酸总量及其组分的影响,为茶园平衡施肥和精准施肥提供理论指导。【方法】采取单因素试验设计,设氮、磷、钾各3个水平及其配比和对照,共14个处理(N1、N2、N3、P1、P2、P3、K1、K2、K3、NP、NK、PK、NPK、CK),在茶树新梢长至1芽3叶时采样,用Li-6400便携式光合测定仪测定茶树的光合生理指标,用氨基酸自动分析仪测定春茶氨基酸总量及组分含量,分别采用凯氏定氮法、钒钼黄比色法和原子吸收分光光度法测定茶树新梢的全氮、全磷和全钾含量。分析不同施肥处理对茶树光合生理指标和春茶氨基酸总量及其组分的影响,并通过逐步回归分析建立Pn与茶树新梢氮、磷、钾含量,Tr、Gs和Ci的回归方程。【结果】NPK处理茶树Pn比CK提高9.70%;P2、P3和NPK处理的Tr显著增加,比CK分别提高10.60%、14.92%、14.25%;NPK处理的Gs显著增加,比CK高23.15%,同时Gs随不同施肥水平表现出与蒸腾速率较一致的趋势,二者的相关性极显著;Ci随氮、磷、钾施用量的增加而上升;WUE随氮、磷、钾施用量的增加而下降。NPK处理的茶树新梢的氮、磷含量较高,相同施肥处理的茶树新梢的磷含量低于氮、钾。逐步回归分析显示,茶树新梢磷含量,Ci和Gs对Pn的直接作用较大,直接通径系数分别为0.3688、-0.8139和0.4677,Pn=12.955+26.624P-0.087Ci+38.233Gs;NPK处理下春茶氨基酸总量及茶氨酸、天冬氨酸、苏氨酸、丝氨酸和胱氨酸等主要氨基酸组分的含量分别比对照提高了27.88%、26.60%、35.78%、35.06%、24.41%和24.41%,与对照差异显著。【结论】新梢磷含量和气孔导度对春茶净光合速率的提高有直接的促进作用,而胞间CO2浓度对净光合速率有一定的消减作用。氮磷钾配施可显著提升茶树新梢叶片的气孔导度并保证茶树新梢中较高的磷含量,从而提高了茶树的净光合速率。氮磷钾肥配施能显著提高春茶氨基酸总量及其组分含量,提高了春茶的品质,表明茶叶中氨基酸总量和茶氨酸等重要组分含量的提高是氮、磷、钾营养共同作用的结果。因此,氮磷钾配合施用可以提高春茶的产量和品质。