UV-B辐射增强对元阳哈尼梯田稻田CH4排放规律的影响

在大田条件下,原位种植传统水稻品种白脚老粳,采用静态箱-气相色谱法研究了UV-B(ultraviolet-B)辐射增强(7.5 kJ m-2d-1)对元阳哈尼梯田海拔1600 m处稻田CH4排放量的影响,同时观测UV-B辐射增强对水稻生长的影响。结果表明:(1)UV-B辐射增强显著降低了水稻植株分蘖末期、拔节孕穗期、抽穗扬花期、成熟期地上部和地下部生物量(P0.05)。(2)UV-B辐射改变了稻田CH4的季节和日排放(成熟期)规律:对照组在拔节孕穗期出现1个排放峰,处理组在拔节孕穗期和成熟期出现2个排放峰;与对照相比,UV-B辐射增强改变了水稻成熟期CH4日排放第2个峰值出现的时间。(3)处理组CH4的季节排放通量与箱内温度的季节变化有显著的正相关性(R=0.789,P0.05)。(4)UV-B辐射增强在分蘖末期、拔节孕穗期、成熟期都极显著提高了CH4的累计排放量(P0.01),分别提高了47.2%,293.8%和74.4%。总之,UV-B辐射增强促进了元阳哈尼梯田传统水稻田CH4的排放。     

UV-B辐射增强对抗除草剂转基因水稻 CH4排放的影响

在大田条件下,研究了UV-B(ultraviolet-B)辐射增强对抗除草剂转基因水稻及亲本常规水稻甲烷(CH4)排放的影响。UV-B辐射设2水平,即对照(CK,自然光),增强(Elevated,14.4 kJ·m-·2d-1),相当于南京地区大气臭氧耗损25%的辐射剂量。结果表明,UV-B辐射增强并没有改变稻田CH4排放通量的季节性变化规律。与对照相比,UV-B辐射增强显著提高CH4排放通量和累积排放量。水稻分蘖期CH4累积排放量最高,占全生育累积排放量的51.55%—61.01%;其次是拔节至孕穗期,占20.00%—26.64%。抗除草剂转基因水稻的CH4排放通量和累积排放量显著低于亲本常规水稻。研究说明,UV-B辐射增强下种植抗除草剂转基因水稻对于减缓稻田甲烷排放有积极意义。     

Methane emissions from rice microcosms: The balance of production, accumulation and oxidation

In rice microcosms (Oryza sativa, var. Roma, type japonica),CH₄ emission, CH₄ production, CH₄oxidation and CH₄ accumulation were measured over an entirevegetation period. Diffusive CH₄ emission was measured inclosed chambers, CH₄ production was measured in soil samples,CH₄ oxidation was determined from the difference between oxicand anoxic emissions, and CH₄ accumulation was measured byanalysis of porewater and gas bubbles. The sum of diffusiveCH₄ emission, CH₄ oxidation, andCH₄ accumulation was only 60% of the cumulativeCH₄ production. The two values diverged during the first 50days (vegetative phase) and then again during the last 50 days (latereproductive phase and senescence) of the 150 day vegetation period. Duringthe period of day 50–100 (early reproductive phase/flowering), theprocesses were balanced. Most likely, gas bubbles and diffusion limitationare responsible for the divergence in the early and late phases. The effectof rice on CH₄ production rates and CH₄concentrations was studied by measuring these processes also in unplantedmicrocosms. Presence of rice plants lowered the CH₄concentrations, but had no net effect on the CH₄ productionrates.     

控释氮肥对抗除草剂转基因水稻田土壤甲烷排放的影响

采用温室盆栽和静态箱-气相色谱法,研究了控释氮肥对抗除草剂转基因水稻和亲本常规水稻稻田土壤甲烷(CH4)排放的影响。供试土壤为潴育型水稻土,氮肥种类为尿素和控释氮肥。结果表明,与对照(尿素)相比,控释氮肥提高了水稻分蘖数、株高、生物量及产量。水稻品种对CH4季节性排放规律没有明显影响,CH4排放通量基本表现为,自水稻移栽后逐渐升高,移栽后62—92 d出现峰值,而后逐渐降低至水稻收获。与对照相比,控释氮肥可显著降低CH4排放通量和全生育期累积排放量。抗除草剂转基因水稻稻田土壤CH4排放通量和累积排放量均显著低于亲本常规水稻。研究认为,一次性基施控释氮肥和种植抗除草剂转基因水稻对有效减缓稻田甲烷排放具有重要意义。     

Estimation of the increase in CH4 emission from paddy soils by rice straw application

The relationship between the amount of CH₄ emission to the atmosphere from submerged paddy soils with rice plants and the application level (0–8 g kg^-1) of rice straw (RS) in soil was investigated in a pot experiment. Amounts of CH₄ emitted from pots with respective RS levels differed between a clayey yellow soil and a silty gray lowland soil. However, the increase in cumulative amounts of CH₄ emission with the increase in the application level of RS was similar in pattern between the two soils, and the increase (Y) was formulated with a logistic curve: x, application level of RS; k, a coefficient for relative CH₄ emission.Since the seasonal variations in coefficients a, b, and c in the logistic equation were also formulated as the function of the sum of effective temperature (E, (T–15); T, daily average temperature), the increase in cumulative amounts of CH₄ emission from any paddy soil by any level of RS application was known to be estimated by the following equation:     

二氧化碳和臭氧浓度升高对春小麦生长及次生代谢的影响

通过开顶式气室(OTCs)研究了OTC对照（自然CO₂浓度约342 μmol·mol^-1,O₃浓度约30 nmol·mol^-1）、高浓度CO₂（550 μmol·mol^-1）、高浓度O₃（浓度为80 nmol·mol^-1）及其交互作用（CO₂ 550 μmol ·mol^-1,O₃ 80 nmol·mol^-1）对春小麦不同发育时期生物量、总酚量、黄酮含量及成熟期产量性状的影响.结果表明：CO₂浓度增加条件下,春小麦生物量和产量性状都显著高于OTC对照（P<0.05）;而O₃浓度升高条件下,小麦生物量降低,株高、穗长、穗粒质量及千粒重也显著低于对照;CO₂和O₃交互作用下各项指标处于二者之间.说明CO₂可以缓解O₃对小麦的负效应,而O₃对CO₂的正效应具有削弱作用,但二者的作用并非简单的叠加.CO₂、O₃浓度增加及其交互作用显著增加了春小麦叶片中的总酚含量,其中两者交互作用的效应更大,但在小麦生长后期,总酚含量增加量比对照有所降低.在小麦生长前期,各处理总黄酮含量均低于对照;而在成熟期,各处理都显著高于对照.     

福建茫荡山黄枝润楠群落多样性比较研究

通过对黄枝润楠群落物种多样性测定,并与邻近区域的其它群落比较,结果表明,该群落显示较高的物种多样性指数,但物种多样性纬度梯度变化不明显,与中国中亚热带东部常绿阔叶林表现出的灌木层＞乔木层＞草本层的格局有所不同。     

苏南丘陵区稻田氧化亚氮的排放特点

氧化亚氮（Ｎ２Ｏ）是一种重要的温室气体,又能破坏臭氧层［１,２］。土壤是大气Ｎ２Ｏ的主要来源［３］,研究结果表明,我国１９９０年排放的Ｎ２Ｏ有９２３６％来自于农田土壤。各种类型稻田Ｎ２Ｏ－Ｎ排放量占化肥施氮量的００３１％～０４８％［４,５］,稻...     

南方双季稻田稻草还田的碳汇效应

利用长期稻草还田定位试验和短期不同稻草还田模式试验,研究稻草还田对南方双季稻田土壤固碳、甲烷排放和综合碳汇的影响.结果表明： 稻草还田能增加土壤有机碳,长期还田的耕层土壤碳汇年增长率为0.07 t C·hm^-2·a^-1,土壤有机碳的表观转化率随着稻草还田量的增加而减少.稻草还田导致稻田甲烷排放量显著增加,其中,NPK添加稻草（NPK+RS）处理早、晚稻期间甲烷排放通量比仅施NPK分别增加了75.0%和251.5%（P<0.01）.稻田甲烷排放随着稻草还田量的增加而增加,在水稻产量和耕作方式相近的条件下,稻草（茬）的甲烷表观转化率接近.综合土壤固碳和甲烷排放的稻田净碳汇,NPK+RS处理负碳汇效应显著,基本与其水稻生物固碳接近,比稻草不还田处理（NPK）增加158.3%;不同还田模式中,稻草覆盖免耕处理能显著减少甲烷排放,其净碳汇（负值）比高桩翻耕处理减少50.9%,有利于水稻高产稳产.     

Soil environmental variables affecting the flux of methane from a range of forest, moorland and agricultural soils

Measurements of the net methane exchange over a range of forest, moorland, and agricultural soils in Scotland were made during the period April to June 1994 and 1995. Fluxes of CH₄ ranged from oxidation –12.3 to an emission of 6.8 ng m^–2 s^–1. The balance between CH₄ oxidation and emission depended on the physical conditions of the soil, primarily soil moisture. The largest oxidation rates were found in the mineral forest soils, and CH₄ emission was observed in several peat soils. The smallest oxidation rate was observed in an agricultural soil. The relationship between CH₄ flux and soil moisture observed in peats (Flux_{CH 4} = 0.023 × %H₂O (dry weight) – 7.44, p > 0.05) was such that CH₄ oxidation was observed at soil moistures less than 325%( ± 80%). CH₄ emission was found at soil moistures exceeding this value. A large range of CH₄ oxidation rates were observed over a small soil moisture range in the mineral soils. CH₄ oxidation in mineral soils was negatively correlated with soil bulk density (Flux_{CH 4} = –37.35 × bulk density (g cm^–3) + 48.83, p > 0.05). Increased nitrogen loading of the soil due to N fixation, atmospheric deposition of N, and fertilisation, were consistently associated with decreases in the soil sink for CH₄, typically in the range 50 to 80%, on a range of soil types and land uses.     

江苏省稻田土壤肥力评价与生产潜力

稻田土壤主要分布于淮河以南地区。随着农田水利条件的改善,土壤生态环境发生变化,其耕作制度也随之不断改革。如在北部的徐淮地区大面积的旱改水,稻田面积增加,粮食产量大幅度上升。据调查统计,全省稻田土壤约占总耕地面积的60%左右,而生产的粮食约占粮食总产量的75%左右。稻田土壤因水分特点与土体构型的不同,可分为爽水、滞水、囊水、漏水与测渗五个类型。爽水水稻土主要分布于太湖平原与里下河     

UV-B增强下施硅对稻田CH4和N2O排放及其增温潜势的影响

大气平流层臭氧损耗导致的地表紫外辐射增强作为全球变化重要问题之一,受到广泛关注。硅是水稻生长有益元素,但施硅是否影响稻田CH_4和 N_2O排放,迄今相关报道尚不多见。通过大田试验,研究UV-B增强下施硅对水稻生长、稻田甲烷(CH_4)和氧化亚氮( N_2O)排放及其增温潜势的影响。UV-B辐照设2水平,即对照(A,自然光)和增强20%(E);施硅量设2水平,即对照(Si0,0 kg SiO_2/hm2)和施硅(Si1,200 kg SiO_2/hm2)。结果表明,UV-B增强降低了成熟期水稻地上部和地下部生物量,而施硅能缓解UV-B增强对水稻生长的抑制作用,使水稻地上部和地下部生物量增加。UV-B增强可显著提高稻田CH_4和 N_2O排放通量和累积排放量,增加稻田CH_4和 N_2O排放的综合增温潜势。施硅能明显降低稻田CH_4排放,促进 N_2O排放,降低稻田CH_4和 N_2O排放的综合增温潜势。研究表明,施硅显著降低稻田CH_4和 N_2O的全球增温潜势,缓解UV-B增强对稻田CH_4和 N_2O的全球增温潜势的促进作用。     

Seasonal variation in methane flux from rice paddies associated with methane concentration in soil water,rice biomass and temperature,and its modelling

To attempt to develop physicochemical and physiological modelling for methane transport from the rhizosphere to the atmosphere through rice plants, methane flux, methane concentration in the soil water, and the biomass of rice were measured in lysimeter rice paddies (2.5 × 4 m, depth 2.0 m) once per week throughout the entire growing season in 1992 at Tsukuba, Japan. The addition of exogenous organic matter (rice straw) or soil amendments with the presence or absence of vegetation were also examined for their influence on methane emissions. The total methane emission over the growing season varied from 3.2 g CH₄ m^-2 y^-1 without the addition of rice straw to 49.7 g CH₄ m^-2 y^-1 with rice straw and microbiological amendment. In the unvegetated plot with the addition of rice straw, there was much ebullition of gas bubbles, particularly in the summer. The annual methane emission due to the ebullition of gas bubbles,from the unvegetated plot with the addition of rice straw was estimated to be almost the same as that from the vegetated site with the addition of rice straw. In the early growth stage, the methane flux can be analyzed by the diffusion model (Flux=Methane concentration × Conductance of rice body) using parameters for methane concentration in the soil water as a difference in concentration between the atmosphere and the rhizosphere, and for the biomass of rice as a conductance of rice body. On the other hand, although the diffusion model was inapplicable to a large extent from the middle to late growth stage, methane flux could be estimated by air temperature and concentration in the soil water. Thus, methane transport from the rhizosphere to the atmosphere through rice plants consisted of two phases: one was an explainable small part by diffusion in rice body; the other was a large part strongly, governed by air temperature. The existence of gas bubbles in the soil may be related to the transition between the two phases     

古田山常绿阔叶林不同演替群落中石栎种子的形态变异

采用空间代替时间的方法研究了浙江古田山植物群落演替过程中石栎种子的形态变异模式,并通过冗余分析法(redundancy analysis,RDA)分析了种子形态特征与生态因子间的关系。结果表明:群落演替阶段是影响种子形态变异最重要的生态因子(P<0.001),海拔的影响次之(P<0.001),坡度的影响微弱(P>0.05)。随着群落演替发展,石栎种子的长度、直径和体积的变异幅度均显著增加(P<0.001);Ⅱ级种子的比例随演替发展逐步下降,Ⅰ、Ⅲ级种子相应逐步增加,种子大小分配由前期的相对均匀转向后期的两极分化。种子空壳率随演替发展逐步上升,演替中期显著高于前期(P<0.001),演替后期又显著高于中期(P<0.001)。推测群落演替引发的群落结构和光环境的复杂化可能是种子形态变异的重要诱因。进一步分析发现,群落演替后期的种子形态特征足以降低石栎种群的更新能力,这可能是石栎在演替后期群落中出现更新受限现象的重要原因。     

江苏省西瓜施肥现状及高产潜力

为了分析高效施肥特征并提高西瓜的产量和品质,调查了江苏省西瓜主产区东台、大丰、泗洪、邳州、东海5个县市的施肥情况.结果表明: 江苏省西瓜平均产量为48325 kg·hm^-2,最高产量为97500 kg·hm^-2;秸秆还田14～15 t·hm^-2可提高西瓜产量;有机肥施用量在30 t·hm^-2以下时,西瓜产量随着有机肥施用量的提高而提高,有机肥施用量大于30 t·hm^-2时西瓜产量有降低趋势.有机肥高产高效和高产低效的农户分别占总调查农户的16.5%和29.1%;氮肥总施用量高产高效和高产低效农户分别占总调查数的14.9% 和26.3%;化学氮肥施用高产高效和高产低效的农户分别占总调查数的19.6%和22.4%;磷肥总施用量高产高效和高产低效的农户分别占总调查数的20.9%和21.8%;化学磷肥施用量高产高效和高产低效农户分别占总调查数的13.7% 和29.5%;钾肥总施用量高产高效和高产低效农户分别占总调查数的14.9% 和26.3%;化学钾肥施用量高产高效农户和高产低效农户分别占总调查数的29.6%和12.2%.与单施基肥相比,基肥和追肥分施可提高西瓜产量.此外,施用叶面肥也可提高西瓜产量.建议高产低效和低产低效农户减量施肥,提高肥料施用效率;低产高效农户调整肥料施用结构和施用时期,提高肥料利用效率.     

磷胁迫对不同种源枫香生长及氮、磷吸收利用率的影响

基于枫香(Liquidambar formosana)作为先锋树种的生态价值及南方红壤缺磷的现状,采用裂区设计,以不同磷水平模拟磷胁迫砂培处理枫香三叶期幼苗,研究7个种源枫香对磷水平的响应差异.结果表明：不同种源枫香间耐磷胁迫差异显著.随磷胁迫的加剧,各种源的生物量和氮、磷吸收量减少,而利用率增加.高磷处理条件下,南昌和宜兴种源枫香生物量和氮、磷吸收量较高,利用率较低,南丹种源枫香的氮、磷利用率较高,吸收量较低;低磷处理时,南昌和南丹种源枫香的磷吸收量、利用率和生物量均较高.说明高磷时,枫香高生物量种源呈高效吸收;而低磷时,则呈高效吸收和高效利用的特点.南昌种源是优良的耐磷胁迫种源,南丹种源次之;磷不是枫香的限制性养分因子.叶片Δ（N/P）、磷效率和生物量可作为确定枫香耐磷胁迫的指标.     

不同施肥措施对我国南方稻田表土有机碳含量及固碳持续时间的影响

基于我国南方38个稻田试验点222个样本的表土有机碳数据,设5种施肥措施类型［无机氮肥(N)、无机氮磷肥配施(NP)、无机氮磷钾肥配施(NPK)、单施有机肥(O)和有机无机肥配施(OF)］,研究了不同施肥措施下我国南方稻田表土有机碳含量的相对年变化量和固碳持续时间.结果表明：5种施肥措施下,稻田表土有机碳含量相对年变化量集中在0～0.4 g·kg^-1·a^-1,两熟制和三熟制的表土有机碳含量相对年均增量分别为0.20和0.26 g·kg^-1·a^-1;有机肥处理(O和OF)比无机肥处理(N、NP和NPK)的表土有机碳含量相对年增量更高,其中,OF处理最高,为0.32 g·kg^-1·a^-1;随着时间的延长,土壤有机碳的累积速率逐渐降低,N、NP、NPK、O和OF处理下表土固碳持续时间分别为22、28、38、57和54年.从土壤固碳角度考虑,有机无机肥配施为我国南方稻田最佳施肥措施.     

水稻土模拟土柱中肥料氮素的迁移转化特征

为了明确肥料氮素在模拟土柱中的迁移转化特征,通过布置室内模拟土柱试验,研究了3倍常规施肥水平下（360 mg·kg^-1）水稻土中矿质氮的变化.结果表明： 不同处理、不同土层间NH₄⁺-N和NO₃^--N含量差异显著.不施肥对照在整个培养期间养分含量变化不大,不同土层间亦没有显著性差异.施用尿素和硫铵后,土壤NH₄⁺-N和NO₃^--N含量显著提高,尤其是0～50 mm土层内,分别达到186.0～2882.1 mg·kg^-1和268.7～351.5 mg·kg^-1,分别相当于对照的4.8～242倍和5.7～316倍,50 mm以下各土层与对照处理相似,表明肥料氮素的迁移转化主要发生在0～50 mm土层内,并且在培养的前14 d变化最大.整个培养期间不同土层内,硫铵处理不同矿质态氮含量是尿素处理的0.7～2.0倍,硝化率是尿素处理的0.9～1.4倍,表明硫铵在水稻土中的转化效率略高于尿素.     

北京东灵山木腐菌主要种类的区系组成及分布特征

于2013年9月中旬和2014年9月下旬,对北京东灵山自然保护区的木材腐朽真菌进行调查和分析。结果表明:在15种树属上共采集1007份标本,经鉴定为128种,隶属于11目24科;其中优势科为多孔菌科、锈革孔菌科和皱皮菌科,分别占该地总种数的27.34%、17.96%和12.5%;优势种为14种,个体数量占全部数量的48.76%,而且绝大部分为白腐菌;通过绘制稀疏曲线,发现在倒木腐烂阶段的中后期,寄主直径为0~5 cm和10 cm,寄主树种为栎属和杨属,基质树皮存在状态下木腐菌数量和物种多样性较高;生长个体数量少的基质含有较多的木腐菌物种;发挥主要降解作用的功能类群中,后续降解者的数量最多,先锋物种和终极分解者数量较少;该地褐腐菌比例较低与缺少针叶树种有关;为了提高该地木腐菌的多样性,可以从保护基质多元化着手。