Characteristics of bacteria in the forest soils under natural vegetation

Characteristics of the predominant bacteria isolated in November and May from the forest soils of both dry and wet types under natural vegetation were studied.

Although Gram-negative rods were the most abundant bacteria in both soil types and in both seasons, their contents were less and other bacteria especially spore-forming ones increased in May.

Among Gram-negative rods in the soil of the dry type in November, the most predominant was those with nonchromogenic rods motile with polar flagella which grew in a simple synthetic media containing glucose or p-hydroxybenzoate and ammonium as the sole carbon and nitrogen sources. In May, the ratio of the bacteria which require amino nitrogen or those with more chomplex nutritional requirement increased. In the soil of moderately wet type, the difference in kinds of bacteria between the two seasons was not so clear as that in the dry type.

Most of Bacillus species obtained in these soils were those requiring amino acids or other growth factors among which B. cereus was most abundant.     

Cloudwater chemistry in the subcooled droplet regime at Mount Sonnblick (3106 M A.S.L., Salzburg,Austria)

Cloudwater and wet precipitation (snow) samples were collected at Mount Sonnblick during two field campaigns in May and November 1991. A newly designed active cloud water samples was used. Concentrations of major anions, cations and carboxylic acids were determined. Cloudwater and wet precipitation samples were generally more acidic in the warm season than in the cold season. Average cloudwater pH was 4.2 in May and 4.5 in November, average pH in snow was 4.4 in May and 5.1 in November. Average levels for sulfate (May: 96 μeq L^?1, November: 64 μeq L^?1) and nitrate (May: 27 μeq L^?1, November: 32 μeq L^?1) in cloudwater at SBO (3 km altitude) were considerably lower than at high mountain sites (0.9–2 km altitude) in the Eastern U.S.A. Cold season levels of sulfate in cloud water at SBO were as low as cloud water levels observed in Alaska. Equivalent concentrations of sulfate, nitrate and ammonium in snow precipitation were basically lower or equal compared to cloudwater but showed higher concentrations and stronger acidity in both phases in May than in November. Cloud to snow ratios for major ions were higher in November showing a wider spread than in May. Average cloud to snow ratios for sulfate were 2.4 in May and 3.5 in November. For nitrate the ratio was 1.7 in May and 2.1 in November. The lower cloud to snow ratios for nitrate are explained by the ability of the ice phase to scavenge nitric acid. Cloud to snow ratios were similar to measurements from the Swiss Alps and generally equal or lower than high elevation cloud to rain ratios from the U.S.A. Cloud to snow ratios for sulfate were used to reconstruct the mixing ratio of sublimation grown ice phase and cloud water droplets during the riming process of the ice particles in the seeder-feeder mechanism. The mixing ratio of ice phase and cloud droplets was estimated to be 1.4 in May and 2.5 in November. Sulfate to nitrate ratios were higher in cloud water than in snow and within the range of values found in North America. Generally, sulfate was more concentrated than nitrate at an equivalent basis for both cloudwater and rainwater. Total equivalent concentrations of acetate were generally higher than those of formate which is in contrast to measurements at remote high elevation sites in the U.S.A.     

基于R2V和AutoCAD的树木年代学方法及其在冀北山地的初步应用

 综合应用AbleSoftwareR2V的矢量化功能和AutoCAD的测量功能,提出一种新的树木年轮测量方法,并用此方法测定了冀北山地广为分布的白榆地径年轮宽度,进而用来尝试过去气候序列的重建。结果表明:5—9月平均气温和总降雨量与年轮指数成正相关,相关系数分别为0.597(α<0.05)、0.695(α<0.05)。以此为基础,建立了5—9月平均气温、总降雨量的转换方程,重建了冀北山地1940—1955年共16年5—9月平均气温和总降雨量。     

移栽时期与烤烟氮肥效应的相关性研究

采用田间试验的方法,研究了不同移栽期（5月5日、 15日和25日）对烤烟氮素的响应及其相关性的影响。结果表明,推迟移栽期至5月15~25日,烤烟产量和地上部各器官（烟叶与茎秆）中含氮量分别平均显著增加5.1%~6.1%和19.8%~55.2%,而且其对氮肥的农学利用率、 生理利用率、 土壤氮素依存率和氮素收获指数分别平均增加37.4%~49.8%、 30.4%~54.8%、 26.9%~29.1%和2.9%~5.7%。移栽期与氮肥农学利用率、 氮肥偏生产力和土壤氮素依存率呈现显著或者极显著正相关关系;氮肥农学利用率与氮肥生理利用率和土壤氮素依存率以及氮肥生理利用率与土壤氮素依存率均呈极显著正相关关系。因此,推迟移栽期至5月15~25日有利于提高氮素养分的增产能力。     

A Multivariate Data Analysis of the Clam Ruditapes Decussatus as Sentinel Organism of the Bizerta Lagoon (Tunisia)

From May 1998 to May 1999, the clams Ruditapes decussatus were collected each month at three stations of the Bizerta lagoon. This paper represents a synthesis between the results already published of catalase (CAT) activity, of glutathione S-transferase (GST) activity and acetylcholinesterase (AChE) activity measured in the clams. Hydrological parameters (temperature, salinity, dissolved oxygen, pH) were determined. Microbial loads (total aerobic bacteria, faecal bacteria and Vibrionaceae) were analyzed in the clams and the sediments. A global Principal Component Analysis was performed including all parameters. On the first principal axis, the temperature, salinity and bacterial loads as well as CAT activities were important factors always opposed to dissolved oxygen, whereas, on the second axis, AChE activity was opposed to pH. Principal Component Analyses were also carried out for results at each station with all parameters. CAT activities were generally high in summer from July to October. AChE activities were low during the months of January, February and March at one station whereas these low activities were shifted to the months of May, June and July at the two other stations. Among the biochemical biomarkers studied, the variations in CAT activities appeared to be the most significant factor of the multivariate analysis. The variations in AChE activity were also significant whereas those in GST activity appeared to be less significant.     

Evidence for the recovery of the waters off the east coast of Nova Scotia from the effects of a major oil spill

The background levels of residual oils in the Western North Atlantic off the east coast of Nova Scotia decreased from approximately 6 to about 2 μgl^?1 during May 1970 to January 1971 following a major spill of Bunker C fuel oil from the tanker ARROW which was wrecked in Chedabucto Bay, Nova Scotia on February 4, 1970.     

三江平原稻田能量通量研究

基于三江平原稻田2005~2007年5~10月涡度相关通量观测数据, 分析了该区稻田能量通量的日变化、季节变化和能量分配特征以及能量平衡状况。结果表明: 三江平原稻田净辐射和潜热通量日变化均表现为明显的单峰特征, 感热通量日变化在水稻发育进入成熟期后才较明显, 而土壤热通量在水稻整个发育期内日变化特征都不明显。稻田净辐射季节变化特征显著, 6月下旬至7月上旬达到最大值18~20 MJ·m^-2·d^-1。潜热通量季节变化与净辐射同步, 最大值为13~19 MJ·m^-2·d^-1。相比之下感热通量较小, 观测期间变化于-3.90~ 3.94 MJ·m^-2·d^-1, 且没有明显的季节变化。5~10月土壤热通量呈下降趋势, 变化于-2.67~3.62 MJ·m^-2·d^-1。三江平原地区稻田能量分配特征明显, 潜热通量占净辐射的比例(LE/Rn) 5~10月平均值为0.67, 表明净辐射大部分以潜热通量形式所消耗, 但生长旺季LE/Rn略大于生长季初期和末期。感热通量占净辐射的比例(Hs/Rn)的季节变化特征与LE/Rn比值相反, 观测期间平均值为0.10。这导致波文比在水稻生长旺季较小而在初期和末期较大。5~10月土壤热通量占净辐射的比例(G/Rn)呈逐渐下降趋势, 其月平均值由5月的0.14下降到10月的-0.08。线性回归法和能量平衡比率均表明三江平原稻田能量明显不闭合, 2005、2006年5~10月能量不闭合度分别为22%和16%, 而2007年能量“过闭合”, 能量平衡比率平均值为1.07。     

定植期及摘心次数对金丝皇菊生长发育的影响

为了筛选出金丝皇菊在清水地区的适宜定植期和摘心次数，以株高15 cm、地径0.3 cm的健壮扦插苗为材料，采用5个定植期(主区)和4个摘心次数(副区)的二因素裂区试验设计，研究了不同定植期及摘心次数对金丝皇菊生长发育的影响。结果表明，不同定植期处理间株高和冠幅差异显著，不同摘心次数处理间株高差异显著，冠幅差异不显著。定植期为5月20和5月30日、摘心次数为2～3次的处理，特级花占10.4%，一级花占19.4%，产值较高。定植期为5月10和5月20日的处理，初花期均为10月20日；定植期为5月30日、摘心1次的处理，初花期为10月20日，摘心2次的处理延迟5 d，摘心3次的处理，延迟8 d；6月9日以后定植的，随着摘心次数的增多，初花期显著推迟。说明定植期为5月20日和5月30日、摘心次数2～3次为金丝皇菊最佳定植期和摘心次数。     

影响湖南早稻生产的五月低温的风险评估

五月低温是影响湖南双季早稻的一种常见的低温冷害。近年来,五月低温发生频率较大,影响早稻生产,对粮食安全生产造成威胁。本文根据湖南省96个气象站1961-2009年5月逐日气象资料和湖南省《气象灾害术语和分级》地方标准,系统分析了五月低温的地域分布特征和发生时段的分布规律。并根据低温对水稻影响的原理,综合考虑低温发生的不同时段和低温程度对冷积温的意义,改进了冷积温计算方法,创建了当量冷积温。同时利用五月低温强度指数,结合湖南早稻种植实际情况,定量评估了基于早稻种植现状的五月低温的生产风险。结果表明：湘北和湘中地区发生五月低温的气象风险较高,且是早稻种植主产区,早稻生产的低温风险较大,是防范重点区域;湘南等地早稻五月低温气象风险小,仅在五月低温发生较重的年份须注意防范;湘西虽是五月低温气象风险的高发区,但由于该区域双季早稻种植面积小,低温对早稻生产影响不大。最后提出了各区域双季早稻生产安排防灾避灾的建议。     

浙江地区甬优15直播稻的最佳播期分析

以“甬优15”水稻为材料,于2017年在浙江龙游农业气象试验站进行5个播期的分期播种试验（A1：5月5日,A2：5月15日,A3：5月25日,A4：6月4日,A5：6月14日）,分析播期对直播稻叶面积指数（LAI）、光合生产、群体干物质积累和转移以及产量的影响。结果表明：适宜播期（A2,5月15日）下,直播稻LAI、群体光合势、群体生长率高,群体干物质积累多,地上部干物质的输出量和转化率大,A2地上部营养器官干物质输出量和转换率分别比A1、A3、A4、A5高7.87%、15.29%、49.43%、56.43%和5.59%、13.18%、28.60%和39.83%。与当地常年单季晚稻适宜播种日期（5月25日）相比,适当早播（5月15日）可增加直播稻的有效穗数、结实率及穗粒数,提高水稻产量,其中A2产量最高（为8879.70kg·hm-2）,分别比A1、A3、A4和A5高392.10、610.20、1445.85和2085.15kg·hm-2。由此可见,甬优15在浙江龙游最佳直播期为5月中旬,偏早或偏迟（5月上旬或5月下旬）播种均将导致减产,而过迟播种（6月及以后）将导致产量严重降低。     

Differential impacts of climate variability on yields of rainfed barley and legumes in semi-arid Mediterranean conditions

Climate change has emerged as a major concern for crop production. This study used a field experiment to examine the differential yield responses of barley, lentil, common vetch, and bitter vetch to weather in the Mediterranean region. Crops were grown in a 10-year rotation trial in Lebanon. Precipitation and temperature were used as explanatory variables in simple linear correlation and standardized multiple-regression analyses. Grain yields were not correlated with annual precipitation. Barley grain yield was correlated positively with precipitation from March to May (r = 0.70) and the rainfall distribution index (r = 0.71), but negatively with mean May temperature (r = –0.62) and absolute minimum temperature in January (r = –0.91). Unlike barley, legume grain yield was not correlated with any rainfall parameters. Common vetch grain yield was negatively correlated with mean May temperature (r = –0.68). Grain yield of the two vetches were also correlated negatively with the absolute minimum temperature in January, but grain yield of lentil was not correlated with any weather variable. Standardized multiple-regression analyses showed that mean May temperature had the strongest influence on grain yield of barley, lentil, and common vetch, indicating that, under climate change, higher temperature may have a more deleterious effect on grain yield than lower rainfall. The negative correlation between common vetch and barley grain yields and temperature in May suggests that early sowing to induce earlier flowering and maturity to escape the hot summer may be an option to increase common vetch and barley grain yields.     

不同时期水分对春小麦产量的影响

运用二次正交旋转组合设计方法,以５、６、７月降水量为变量因子,利用防雨棚控制降水环境,研究了不同时期水分对春小麦产量的影响。结果表明,５、６月份（拔节、抽穗期）降水量是小麦产量的限制因子;７月份（灌浆期）降水量对产量影响较小。一般在５、６月份降水较多的情况下,产量较高;而７月份降水较多时产量较低。通过对模型优化分析,提出了两品种小麦适宜综合水分指标为：喜水肥品种龙麦１２号５、６、７月平均降水量为：６１．４、１０７．３、１３７．０ｍｍ;抗旱品种克旱１０号５、６、７月平均降水量为：４４．０、１０６．６、１１７．０ｍｍ。在此条件下,小麦产量可望达２２５ｇ／（６６６．７ｍ２）。     

Timing of planting is crucial for cotton yield

Abstract

A field study has been conducted to evaluate the importance of planting dates on earliness and second crop seed cotton yield in two cotton cultivars (Gossypium hirsutum L.). The experiment was designed as a split-plot with three replications in which planting dates were the main plots and cotton cultivars were subplots. Five planting dates were established at about 15-day intervals from mid-April to mid-June (15 April, 1 May, 15 May, 1 June, and 15 June). Data collected in both years indicated that planting on 15 April increased the seed cotton yield by 15%. 1 June planting resulted in lower yield (28%), micronaire (15%) and strength (10%) compared to 1 May. Short fibre content was 35% higher for the 15 June planting than for 1 May planting. Cultivar responses differed with planting date. The existence of cultivar×planting date interaction on yield highlights the importance of selecting the right cultivar for the specified planting date. An early planting production system for cotton has the potential to increase yield and quality. Planting cotton as a second crop after cereals could also be feasible for the regions which have an expanding textile industry, although yield and quality are not as high as in crops grown at optimum planting date.     

Biomonitoring of Metal Availability in the Southern Basin of the Lagoon of Venice (Italy) by Means of Macroalgae

Macroalgae of the following species: Ulva laetevirens, Enteromorpha intestinalis, Gracilaria verrucosa and Sargassum mutycum, were used to monitor metal concentrations (Al, Mn, Fe, Cu, Zn, Cr, Co, Ni, Cd) in the waters of the southern basin of the Lagoon of Venice. Sampling was performed at 5 sites, gradually moving north from the town of Chioggia. Species-specific seasonal variability was observed, with significant increases of Cd in U. laetevirens in January,Al and Pb in E. intestinalis in May, and Al and Ni in S. mutycum in January. Seasonal relative frequencies of metalpeak concentrations emphasize the occurrence of Pb peaks in May for all the studied species. Analysis of inter-site variability shows significant increases of Al, Fe, Cr and Pb in U. laetevirens at the Hydro-Biological Station, located within the town of Chioggia. Metal concentrations in algae are comparable with those in other areas of the lagoon, although Fe, Cr and Ni concentrations are lower than in the northern and central basins.This result fits dissolved metal concentrations determined byother authors, but does not correspond to the reported presence ofCr in the sediments of the southern basin. The hypothesis isdiscussed according to which low Cr levels in algae reflect Crspeciation in sediments.     

Establishment of Hybrid Arctic Bramble under Field Conditions

The effect of different factors on plant diameter and yield in hybrid arctic bramble (Rubus arcticus nothosubsp. stellarcticus) was examined in two field experiments with a factorial design. The studied factors included planting time (August, September, May or June), plant type (bare-rooted or potted plants) and ground cover (no ground cover or mulching with a dark plastic film). Development of bare-rooted and potted plants did not differ when transplanted in the autumn and in May. Potted plants developed better than bare-rooted plants when transplanted in June. In one year, plants transplanted in May developed best, while in another, plants transplanted in the autumn developed best. Mulching with a dark plastic film improved plant development. The rate of vegetative development during the first growth season was reflected in the yields in both the first and the second harvest year; the greater the plant diameter after the first growth season, the higher the yield.     

Integrated data analysis in the presence of emigration and mark loss

Integrated data analyses are becoming increasingly common in studies of wild animal populations where two or more separate sources of data contain information about common parameters. These types of analyses provide robust parameter estimates which fully reflect all available information, as well as estimates of parameters that would be unidentifiable in a separate analysis. In this article we present an integrated Bayesian analysis of four long-term datasets (counts, two mark-recapture-recovery time series, and productivity) relating to a colony of common guillemots (Uria aalge) on the Isle of May, southeast Scotland. A complication when considering the dynamics of populations of this kind is the unobservable emigration of immature animals. In the analysis of mark-recapture-recovery data, the rate of emigration is frequently confounded with that of mark loss and it is only possible to estimate the product of these parameters. By combining all available data for the Isle of May guillemots in an integrated population model, we are able to estimate these parameters separately and thus obtain improved estimates of prerecruitment emigration.     

汶川地震灾区归一化植被指数变化监测分析

提取归一化植被指数合成旬最大植被指数,研究地震重灾区域的植被状况.结果表明:1)盆地西部和北部山区,植被在4月下旬到5月底呈现自然生长规律,并且存在一条以旬最大植被指数为标记的稳定边界线来区分盆西山区和盆地农田;2)2008年地震前期,4月下旬的旬最大植被指数好于5月上旬,地震发生的5月中旬,旬最大植被指数在成都平原、德阳和阿坝州交界的山区明显减小,5月下旬,大部分区域旬最大植被指数都在减小;3)2009年5月中旬的旬最大植被指数是最好的,5月下旬,盆地中的旬最大植被指数值减小;4)地震使得在盆西山区和盆地农田之间通过旬最大植被指数表征的稳定边界被破坏.     

Modeling the elemental mercury cycle in Pallette Lake,Wisconsin, USA

The spatial and temporal distribution of elemental Hg (Hg°) and reactive Hg (Hg_R) has been studied on Pallette Lake, Wisconsin during May – August, 1993 and May, 1994. In general, Hg° concentrations near the lake surface greatly exceeded saturation with respect to atmospheric Hg° indicating a flux out (?) of the lake. Evasional losses were estimated using a thin film model and averaged ?101 pmol m^?2 d^?1 during July and August, 1993. A large portion of atmospherically deposited Hg is re-emitted. Thus, in-lake Hg° production' and evasion to the atmosphere will significantly reduce the amount of Hg which is transported to the sediments, the principal site of methylation. Laboratory experiments were conducted to ascertain the rate of Hg° formation from Hg(II). Reduction was significantly lower in heat sterilized lakewater suggesting Hg° production was biologically mediated. The temporal distribution of epilimnetic Hg°, as measured at the lake center, was influenced by Hg° evasion, Hg° production and advective transport of water parcels of differing Hg content. Spatial gradients in Hg° and Hg_R were identified and a transport model was employed to estimate the advective flux of Hg°. The importance of atmospheric deposition and sediment-water interaction as sources of Hg_R to epilimnetic waters were examined. Porewater concentrations of Hg° and Hg_R were determined on several occasions. During May, 1994, the depletion of lakewater Hg_R following a input pulse due to rain was observed and the estimated removal rate (16–20% d^?1) agrees well with reduction rates obtained in the laboratory (23% d^?1).     

Seasonal Variation in Nutrient Status of Foxglove Leaves

The seasonal variation of mineral elements and the relationships among them were studied in natural populations of foxglove (Digitalis obscura). Young and mature leaves were collected in 10 different populations and on four sample dates (May, July, October, and February). Leaf mineral elements [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu)] were determined. The highest concentrations of N, P, and K in young leaf were recorded in May, followed by a decrease in the other months, while in contrast Ca and Fe showed the lowest concentration in May. Mature leaves showed differential seasonal behavior. Besides seasonal variations, significant fluctuations of N/P and Ca/Mg ratios were observed in young leaves. Strong positive correlations existed among N, P and K, while negative correlations were found between Ca and N, P, or K.