Transport of Nitrogen Assimilation in Xylem Vessels of Green Tea Plants Fed with NH_4-N and NO_3-N

An experiment was carried out to study the transport process of nitrogen （N） assimilation from tea roots by monitoring the dynamic composition of N compounds in xylem sap after 15^N-NO3 and 15^N-NH4 were fed to the root of tea plants （Camellia sinensis L.）. Results showed that the main amino acids were glutamine, theanine, axginine, asparic acid and glutamic acid, which accounted for 49%, 17%, 8%, 7%, and 4%, respectively, of the total amino acids in the xylem sap. After the tea plants were fed with 15^N-NO3 and 15^N-NH4 for 48 h, the amount of total amino acids in xylem sap significantly increased and those fed with 15^N-NH4 had higher increment than those with 15^N-NOa. Two hours after 15^N- NO3 and 15^N-NH4 were fed, 15N abundance in glutamine, asparagine, glutamic acid, alanine, and arginine were detected and increased quickly over time. This indicated that it took less than 2 h for NO3-N and NH4-N to be absorbed by tea roots, incorporated into the above amino acids and transported to the xylem sap. Rapid increase in 15^N-NO3 in the xylem sap of tea plants fed with 15^N-NO3 indicated that nitrate could be directly transported to the xylem sap. Glutamine, theanine, and alanine were the main amino acids transported in xylem sap of tea plants fed with both 15^N-NO3 and 15^N-NH4.

Increased dependence on nitrogen-fixation of a native legume in competition with an invasive plant

Suppression of roots and/or their symbiotic microorganisms,such as mycorrhizal fungi and rhizobia,is an effective way for alien plants to outcompete native plants.However,little is known about how invasive and native plants interact with the quantity and activity of nutrient-acquisition agents.Here a pot experiment was conducted with monoculture and mixed plantings of an invasive plant,Xanthium strumarium,and a common native legume,Glycine max.We measured traits related to root and nodule quantity and activity and mycorrhizal colonization.Compared to the monoculture,fine root quantity(biomass,surface area)and activity(root nitrogen(N)concentration,acid phosphatase activity)of G.max decreased in mixed plantings;nodule quantity(biomass)decreased by 45%,while nodule activity in Nfixing via rhizobium increased by 106%;mycorrhizal colonization was unaffected.Contribution of N fixation to leaf N content in G.max increased in the mixed plantings,and this increase was attributed to a decrease in the rhizosphere soil N of G.max in the mixed plantings.Increased root quantity and activity,along with a higher mycorrhizal association was observed in X.strumarium in the mixed compared to monoculture.Together,the invasive plant did not directly scavenge N from nodule-fixed N,but rather depleted the rhizosphere soil N of the legume,thereby stimulating the activity of N-fixation and increasing the dependence of the native legume on this N source.The quantity-activity framework holds promise for future studies on how native legumes respond to alien plant invasions.

Root characteristics and yield of rice as affected by the cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application

To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems,we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application(SDN)on the morphological and physiological characteristics of double cropping rice.Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant,but the morphological characteristics of the population roots were largely different.Specifically,SDN significantly increased the morphological indexes of the root population such as root fresh weight,root volume,root number,root length and root dry weight.The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant,but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering,heading and mature stages.In addition,SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap.Compared to the traditional cultivation pattern(CK),SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice,respectively.Meanwhile,SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice,respectively.In addition,SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK.Furthermore,SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seedsetting rate.The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017,and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017,respectively.Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.

Effect of Plant Growth-Promoting Rhizobacteria at Various Nitrogen Rates on Corn Growth

Plant growth-promoting rhizobacteria (PGPR) colonize plant roots and promote plant growth by producing and secreting various chemical regulators in the rhizosphere. With the recent interest in sustainable agriculture, an increasing number of researchers are investigating ways to improve the efficiency of PGPR use to reduce chemical fertilizer inputs needed for crop production. Accordingly, greenhouse studies were conducted to evaluate the impact of PGPR inoculants on biomass production and nitrogen (N) content of corn (Zea mays L.) under different N levels. Treatments included three PGPR inoculants (two mixtures of PGPR strains and one control without PGPR) and five N application levels (0%, 25%, 50%, 75%, and 100% of the recommended N rate of 135 kg N ha−1). Results showed that inoculation of PGPR significantly increased plant height, stem diameter, leaf area, and root morphology of corn compared to no PGPR application under the same N levels at the V6 growth stage, but few differences were observed at the V4 stage. PGPR with 50% of the full N rate produced corn biomass and N concentrations equivalent to or greater than that of the full N rate without inoculants at the VT stage. In conclusion, mixtures of PGPR can potentially reduce inorganic N fertilization without affecting corn plant growth parameters. Future research is needed under field conditions to determine if these PGPR inoculants can be integrated as a bio-fertilizer in crop production nutrient management strategies.

The plant-enhanced bio-cathode:Root exudates and microbial community for nitrogen removal

A plant bio-electrochemical system(PBES) was constructed for organic pollutant removal and power generation. The bio-cathode, composed of granular activated carbon(GAC), stainless wire mesh and a plant species(Triticum aestivum L.), was able to catalyze cathodic reactions without any requirement for aeration or power input. During the 60-day-long operation, an average voltage of 516 m V(1000 Ω) and maximum power density(Pmax) of 0.83 W/m^3 were obtained in the PBES. The total nitrogen removal and total organic carbon removal in the PBES were 85% and 97%, respectively. Microbial community analyses indicated that bacteria associated with power generation and organic removal were the predominant species in the bio-cathode, and plant-growth-promoting rhizobacteria were also found in the PBES. The results suggested that the coupling of plants with the GAC cathode may enhance the organicmatter degradation and energy generation from wastewater and therefore provide a new method for bio-cathode design and promote energy efficiency.

Why are Nitrogen Concentrations in Plant Tissues Lower under Elevated CO_2? A Critical Examination of the Hypotheses

Plants grown under elevated atmospheric [CO2] typically have decreased tissue concentrations of N compared with plants grown under current ambient [CO2]. The physiological mechanisms responsible for this phenomenon have not been definitely established, although a considerable number of hypotheses have been advanced to account for it. In this review we discuss and critically evaluate these hypotheses. One contributing factor to the decreases in tissue N concentrations clearly is dilution of N by increased photosynthetic assimilation of C. In addition, studies on intact plants show strong evidence for a general decrease in the specific uptake rates （uptake per unit mass or length of root） of N by roots under elevated CO2. This decreased root uptake appears likely to be the result both of decreased N demand by shoots and of decreased ability of the soil-root system to supply N. The best-supported mechanism for decreased N supply is a decrease in transpiration-driven mass flow of N in soils due to decreased stomatal conductance at elevated CO2, although some evidence suggests that altered root system architecture may also play a role. There is also limited evidence suggesting that under elevated CO2, plants may exhibit increased rates of N loss through volatilization and/or root exudation, further contributing to lowering tissue N concentrations.

4种氮肥用量对‘紫嫣’茶树生长发育的影响

【目的】研究氮肥用量对‘紫嫣’茶树生长和生化成分含量的影响,为‘紫嫣’茶树高产高效栽培体系的建立提供理论依据。【方法】试验设置4个尿素水平(0、375、525、675 kg/hm^(2)),比较不同氮肥用量下‘紫嫣’茶树产量、品质成分和氮磷钾含量的差异。【结果】不同施氮量处理均能不同程度地促进‘紫嫣’茶树新梢生长、芽叶品质成分含量及氮磷钾的积累,提高土壤酶活性,以560 kg/hm^(2)尿素处理效果显著。此处理下,‘紫嫣’茶树春茶产量显著增加27.44%,春梢的水浸出物、氨基酸和茶多酚含量显著提高10.41%、27.38%、10.09%,叶绿素、类胡萝卜素和花青素显著提高37.35%、25.00%、19.57%。而夏梢的水浸出物、茶多酚含量和叶绿素总量较不追肥处理仍显著提高。【结论】适量氮肥利于‘紫嫣’茶树生长,使产量和品质提高,但随着氮肥用量增加,氮肥的促进效应降低。因此,对‘紫嫣’茶园(黄壤土pH=4.66,有机质27.43 g/kg,全氮1.24 g/kg,速效磷32.05 mg/kg,速效钾81 mg/kg)宜追施525 kg/hm^(2)尿素。

茶树根腐病拮抗真菌的筛选、鉴定及防病促生特性研究

为获得对茶树根腐病原菌Fusarium cugenangense具有良好拮抗效果的拮抗真菌,采用稀释涂布平板法从茶树根腐病根际土壤分离出真菌菌株,利用平板对峙法筛选出拮抗活性较高的菌株,基于形态学观察和ITS测序分析对其进行鉴定,测定其防病促生指标、抑菌谱、挥发性代谢物及难挥发性代谢物的抑菌活性,并评估拮抗菌株发酵液对茶树根腐病的抑菌能力。结果表明,筛选获得一株对茶树根腐病原菌F.cugenangense具有良好抑制效果的菌株CA5,平板对峙抑菌率为77.39%,鉴定为嗜松篮状菌Talaromyces pinophilus;菌株CA5具有产生纤维素酶、β-1,3葡聚糖酶和几丁质酶的能力,还具有解无机磷、解有机磷、解钾、固氮、产铁载体、产IAA以及产氨能力;菌株CA5对其他8种植物病原菌的抑制率均大于60%,抗菌作用具有广谱性;其挥发性代谢物和难挥发性代谢物对茶树根腐病原菌菌丝生长的抑制率分别为14.90%和44.33%,发酵液、菌悬液、无菌发酵滤液对茶树根腐病原菌菌丝生长的抑制率分别为73.42%、67.32%、25.75%;盆栽试验结果表明,菌株CA5对茶树根腐病防效达56.11%,且对茶树幼苗生长具有促进作用。综上,菌株CA5在防控茶树根腐病方面具有巨大应用潜力。

煤矿复垦区博落回生物量及其分配特征对氮的响应

为探究博落回(Macleaya cordata)在不同施氮梯度下各生育期生物量及总生物量分配的动态变化规律,设置5个施氮水平:CK(0 kg·hm^(−2))、N_(1)(75 kg·hm^(−2))、N_(2)(150 kg·hm^(−2))、N_(3)(225 kg·hm^(−2))、N_(4)(300 kg·hm^(−2)),从2020年起开展为期两年的连续施氮试验,揭示博落回在贫瘠土壤中的生长适应特征。结果表明:1)N_(3)、N_(4)各时期博落回的冠生物量、根系生物量和总生物量均显著高于CK、N_(1)和N_(2)(P<0.05)。2)博落回的根冠比在不同年份有差异,第1年所有处理的根冠比在6月最低,分别为0.04、0.12、0.09、0.15和0.16,第2年在8月最低,分别为0.20、0.18、0.08、0.06和0.10;2021年6月和8月,CK的根冠比都高于其他处理。3)2020年10月N_(3)的茎叶比显著高于其他处理(P<0.05),其他处理的茎叶比各月份间差异不大;2021年各处理间茎叶比随恢复时间逐渐增加,在11月达到最大,分别为2.82、1.19、1.23、1.89和2.05。综上所述,建议对煤矿复垦区博落回施加225~300 kg·hm^(−2)的氮,以此来促进博落回在贫瘠土壤中的快速定植,本研究可以为缺氮土壤中博落回的生长适应性研究提供理论依据。

氮添加对茶树与入侵杂草空心莲子草种间竞争的影响

【目的】探讨氮添加对茶树和茶园入侵杂草空心莲子草种间竞争的影响,以期为全球环境变化下的茶园杂草防控提质增效及茶叶绿色生产提供理论依据。【方法】通过设置氮素处理(对照、施氮)、播种方式(单种、混种)和物种属性(茶树、空心莲子草)3因子盆栽试验,分析信阳10号茶树品种与其伴生杂草空心莲子草在生物量、形态、营养、色素及光合荧光等方面的异质性响应。【结果】茶树的根长、根面积、叶面积、生物量、总碳含量、碳氮比(C∶N)、叶绿素指数和类黄酮指数均极显著高于空心莲子草(P<0.01,下同),而空心莲子草的总氮含量、氮平衡指数、花青素指数和稳态光适应光化学猝灭系数(qP-Lss)均显著(P<0.05,下同)或极显著高于茶树。施氮导致空心莲子草的最大茎长显著增加1.14倍,根冠比极显著下降67.28%;施氮导致茶树和空心莲子草的总氮含量分别显著下降29.79%和6.03%,茶树C∶N显著提高39.47%。施氮导致空心莲子草的最大光量子效率(F_(v)/F_(m))显著下降19.62%,单种中空心莲子草的最大荧光(Fm)和光稳态实际光量子效率(QY-Lss)分别显著下降22.56%和48.36%,混种中茶树和空心莲子草的QY-Lss分别显著下降68.99%和56.19%。【结论】信阳10号茶树品种在应对杂草竞争时具有较高的单株竞争优势、光合效率及次生防御能力,而空心莲子草具有较高的氮吸收能力、抗逆性及光合活性;施氮相对提升了茶树在光合生理方面的竞争优势,但加剧空心莲子草对地上资源的抢占。

控释氮肥对茶叶产量、品质和氮素利用效率及经济效益的影响

通过田间试验,研究了控释氮肥对茶园土壤无机氮含量、茶叶产量、品质成分、氮素利用效率和茶叶中氮磷等主要矿质元素吸收的影响,比较了不同施肥方式对经济效益的影响。结果表明,不同氮肥处理间土壤无机氮含量无显著差异,但控释肥处理土壤中无机氮变化幅度较小,而且比较稳定。与普通氮肥相比,控释氮肥单施或与普通氮肥配施,茶叶产量分别提高7.5%和15.2%。施控释氮肥对茶叶游离氨基酸总量、茶多酚含量、酚氨比值不会产生明显的影响。控释氮肥能促进茶树对氮、磷等主要矿质元素的吸收,提高茶树新梢氮素利用率,其中新梢氮素利用效率(NUE),控释氮肥和普通氮肥配施比普通氮肥高5.38个百分点,比单施控释氮肥高2.39个百分点,新梢氮素偏生产率(PNE),控释氮肥和普通氮肥配施比普通氮肥处理高1.16 kg·kg-1,比单施控释氮肥高0.57 kg·kg-1。与普通氮肥相比,单施控释氮肥每年每公顷增加纯收入0.93万元,控释氮肥和普通氮肥配施增加纯收入2.01万元。本研究结果表明,控释氮肥与普通氮肥配施增产、增效明显。

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。

生物质炭配施氮肥对茶树生长及氮素利用率的影响

通过水泥池小区试验,采用^(15)N同位素示踪技术,研究了生物质炭配施氮肥对茶树生长及氮素利用率(茶树吸收、土壤氨挥发、N_2O和土壤残留量)的影响。结果表明,与不施生物质炭且不施氮肥(B_0N_0)处理相比,施氮能促进茶树的生长发育,茶树株高、树幅和基部径粗均显著增加,茶叶增产68.06%～112.63%。生物质炭对茶叶产量的影响因施氮量而异,在不施氮(N_0)和减量化施氮(N_1)条件下,配施生物质炭处理茶叶产量增加8.82%和8.75%,而常规施氮(N_2)条件下配施生物质炭处理茶叶产量略有降低,但差异均不显著。与B_0N_0处理相比,施氮处理土壤氨挥发和N_2O排放量显著增加;在N_1条件下,配施生物质炭(B_1N_1)处理氨挥发和N_2O累积排放量分别降低了5.87%和4.99%;在N_2条件下,配施生物质炭(B_1N_2)处理氨挥发和N_2O累积排放量分别降低了9.97%和11.41%,B_1N_2处理氮素减排效果更好。与单施氮肥处理相比,配施生物质炭均能增加茶树各器官氮含量、^(15)N丰度和Ndff值,有利于茶树对氮素的吸收利用。与单施氮肥处理相比,配施生物质炭处理茶树^(15)N利用率和^(15)N残留率分别增加了0.46～3.93百分点和4.09～14.37百分点,^(15)N损失率下降4.54～18.30百分点,其中B_1N_1处理效果优于B_1N_2处理。总体而言,生物质炭配施氮肥促进了茶树对氮的吸收,增加土壤氮素持留,并降低氮素气态损失,从而提高了氮素利用率,以减量化施氮配施生物质炭(B_1N_1)处理茶树能起到"减氮增产"效果,具有良好的应用前景。

沟灌方式和水氮对玉米产量与水分传导的影响

采用正交试验设计,用美国Dynamax公司生产的高压流速仪(High Pressure Flow Meter,简称HPFM)的瞬时法原位测定大田玉米拔节期、抽雄期和蜡熟期的根系及冠层水分传导(简称根及冠层水导),研究了不同沟灌方式、灌水量和施氮量对玉米水分传导、产量和植株氮的影响。结果表明,玉米根系或冠层水导最大值均在拔节期取得,均随生育期的推移逐渐变小。通过对玉米产量和水分传导综合比较得出最优组合处理是隔沟交替灌(简称交替沟灌)中水高肥:即沟灌方式为交替沟灌、灌溉量为282mm、施氮量为240Kg·hm-2的处理。可见,交替沟灌在根区两侧反复的对干燥侧根系进行灌水,促进根系和冠层水导增大,提高了根系对水肥的吸收利用和传输效率,使得植株氮含量较高,产量较大。

苕溪流域茶园不同种植模式下地表径流氮磷流失特征

为探讨苕溪流域不同种植模式下茶园地表径流氮磷养分流失特征,于2010年5-10月对等高种植和顺坡种植2种种植模式下茶园地表径流水样进行取样测定,分析径流水样中的氮磷元素各指标的含量、形态特征及其随时间的变化规律。结果表明:无论是顺坡种植还是等高种植,茶园径流中氮素各指标含量的峰值均出现在6月底或7月初,茶园径流中磷素各指标含量的峰值出现在6月底、7月初或9月初。在整个监测时期内,等高种植茶园径流中总氮、硝氮、铵氮含量分别比顺坡种植茶园低8.54%～43.01%,4.05%～46.70%,5.92%～33.19%,但2种种植模式间不存在显著差异;等高种植茶园径流水中总磷、可溶态总磷、颗粒态磷的含量分别比顺坡种植低8.51%～31.07%,0.39%～17.91%,8.45%～36.86%,2种种植模式之间径流水中总磷、颗粒态磷含量存在极显著差异,可溶态磷含量不存在显著差异。无论是顺坡种植还是等高种植,硝态氮均为茶园氮素地表径流流失的主要形态,颗粒态磷则是茶园磷素地表径流流失的主要形态。总的来说,等高种植模式能有效地截留茶园氮磷营养元素,防止其随地表径流流失。

茶树根际土壤性质及氮肥的影响

本文报导了对盆栽茶树根际土壤性质的研究结果。经外力抖落后仍粘在根系上的土壤作为根际土壤,其余土壤为非根际土壤。施氮显著降低土壤pH、交换性K、Ca、Mg含量和盐基饱和度,增加水溶性铝、有机交换态铝和吸附羟基态铝的含量。与非根际土壤相比,根际土壤pH、交换性Ca、Mg和盐基饱和度明显降低,而交换性K高于非根际土壤。根际土壤的水溶性铝、交换性铝、交换性铝饱和度和吸附羟基态铝的含量显著高于非根际土。上述结果说明茶树根际土壤明显酸化,增强了土壤铝有效度。铝在茶树根际微域环境中的这种变化,可能在茶树吸收铝的过程中起着重要作用。

茶树根愈伤组织及发状根诱导的研究

为了获得茶树发状根,生产茶叶中的有用物质,以大田茶树的根为材料,在离体培养下对其诱导发状根.结果表明,从茶树根愈伤组织中诱导出的发状根具有生长快、无向地性、密生白色根毛和较强的分枝能力.发状根分枝,存在直接分枝和在发状根上出现瘤状突起后在其附近发生侧根2种类型.发状根及其愈伤组织轮换在不同组分的培养基上继代培养,对发状根的分化与增殖有明显的促进作用.根外植体在本研究的所有培养基上都诱导出了愈伤组织,不同品种的根外植体愈伤组织诱导率存在明显差异.

茶树插穗生根过程中可溶性糖等生化成分的动态变化

分析了茶树插穗生根过程中可溶性糖、总氮、茶多酚等生化成分含量及相互比值动态变化。结果表明,可溶性糖是主要的生根促进物质,茶多酚是主要的生根抑制物质,总氮含量与生根关系不大。不同生根率品种间糖/氮比值、糖/酚比值与其插穗生根率成正相关。插穗糖/酚比值与内源激素IAA/ABA比值一起,可以作为判断茶树插穗生根能力的主要指标[1]。

田间条件下不同园龄茶树氮、磷、钾养分需求规律的研究

本文通过分析大田条件下1、2、3、5和10龄龙井43茶园头年秋天整株茶树、第二年采摘新稍、修剪物和落叶的生物量以及氮、磷、钾养分量,研究不同园龄茶树氮、磷、钾养分需求规律。1龄茶园到5龄茶园,茶树地上部生物量、氮、磷、钾养分量分别增加约32倍、21倍、25倍、29倍,到10龄茶园,与5龄茶园相比,仅分别增加约71%、17%、13%、14%。从1龄到2龄茶园,茶树氮、磷、钾的年养分需求量分别为90.01、5.71、31.11kg/hm2,从2龄到3龄茶园,茶树氮、磷、钾的年养分需求量分别为122.74、9.63、45.14kg/hm2,从3龄到4龄茶园,茶树氮、磷、钾的年养分需求量分别为144.03、10.33、47.99kg/hm2。幼龄茶树经过定型修剪后,吸收的养分有一部分通过修剪物和落叶回归土壤,因茶树生长(不包括修剪物和落叶等)并留存在茶树上的养分量占总量的43.9%、48.7%、61.3%左右。进入青年期,如5龄茶园,茶树氮、磷、钾的年养分需求量分别约为164.4、12.68、71.29kg/hm2。进入采摘后,茶树所需的养分主要用于新稍生长,一部分分配到修剪物和落叶之中,因茶树生长(不包括修剪物和落叶等)并留存在茶树上的氮、磷、钾养分量比较稳定且只占较少份额(氮、磷、钾养分量分别仅约为7.54、0.53、5.44kg/hm2)。本试验对田间条件下不同生育期的茶树氮、磷、钾养分需求量的研究建立了试验分析方法,为进一步研究茶树养分需求规律提供了一条新的思路。

氮肥减施对茶园土壤细菌群落结构的影响研究

为了研究不同减氮模式对茶树地下部分细菌菌落结构的影响。设置16 kg/667 m^(2)纯氮(减氮55.6%处理A),26 kg/667 m^(2)纯氮(减氮27.8%处理B),36 kg/667 m^(2)纯氮(常规施肥C),不施氮(CK)共4个施氮水平,对根际及非根际0-20 cm土壤、非根际20-40 cm土壤36个样品进行16S rRNA序列测定,利用IonS5^(TM)XL高通量测序平台对不同减氮处理的土壤细菌群落结构进行分析。试验结果表明:A、B、C三种施肥水平下,根际、非根际0-20 cm土壤及非根际20-40 cm土壤的细菌OTUs分别为505、854及835个,其中特异OTUs随着施氮量逐渐增加而降低。土壤细菌丰度和多样性分析显示施氮量为26 kg/667 m^(2)(减氮处理B)在根际与非根际0-20 cm土壤中细菌丰度较高,细菌多样性最高,土壤碳通量的结果亦证明了减氮处理B土壤中微生物较多。施肥茶园地下部分在门水平上的优势菌基本为氮代谢相关菌类,其中共有3个优势类群,分别为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi)。在属的水平上,根际土壤与非根际土壤细菌优势菌完全不同。适当减氮处理B茶园土壤中细菌菌落多样性较多,丰度较高,并主要集中在养分吸收利用的根际及周边土壤中,有利于茶园养分的高效利用。