Effects of open-top chamber fumigations with ozone on three fungal leaf diseases of wheat and the mycoflora of the phyllosphere

Spring wheat (Triticum aestivum L. cv. Turbo) was exposed in open-top chambers to six different ozone levels (8-h daily means from 12.4 to 122 microg m(-3)), to non-filtered air and to chamberless field conditions for 31 days from seedling stage through ear emergence. Powdery mildew (Erysiphe graminis DC. f.sp. tritici Marchal) which developed during the exposure period was significantly enhanced from 0.3/0.6% (two chamber replicates), 1.2/2.1%, 0.9/2.2% in charcoal-filtered air (CF) to 1.5/1.6%, 3.7/4.3%, 4.4/4.6% at the highest level of ozone, on the flag leaf, second and third leaf position, respectively. Post-exposure inoculation with Septoria nodorum Berk. led to increases of disease severity on the flag leaf from 40.9/43.6% in CF to 66.3/70.6% at the highest ozone concentration and on the ears from 15.7/16.5% to 26.3/26.6%. In the same comparison, severity of spot blotch following inoculation with Bipolaris sorokiniana (Sacc.) Shoem. (syn. Helminthosporium sativum Pamm., King et Bakke) was increased on the flag leaf from 3.6/8.9% to 12.3/23.4%. The three diseases examined correlated significantly with the ozone treatments in fumigated chambers. Disease severity was enhanced even on undamaged plant tissue (flag leaves). Infections of the two facultative pathogens on lower leaf positions started only in part from visible ozone lesions, mildew did not start from such lesions. No significant effects of ozone in the chambers on the saprobial colonization of the phyllosphere were detected, whereas there were marked differences in this respect between plants from the field and the chambers. At the highest ozone treatment, contents of chlorophyll a and carotenoids on the second leaf position declined significantly, which was associated with symptoms of premature senescence. Senescing effects of ozone are therefore assumed to be one major factor in predisposing wheat for necrotrophic leaf pathogens. Surprisingly, injurious and predisposing effects of ozone were completely absent in chambers supplied with non-filtered air containing ambient ozone at doses equivalent to those in CF + ozone chambers. Evidently, biological effects of ozone in pure air and in ambient air may differ markedly.     

EFFECTS OF CLIMATE VARIABILITY ON RIVERS: CONSEQUENCES FOR LONG TERM WATER QUALITY ANALYSIS1

ABSTRACT: Associations between the El Nino Southern Oscillation (ENSO) climate pattern and temporal variability in flow and 12 water quality variables were assessed at 77 river sites throughout New Zealand over a 13‐year period (1989 through 2001). Trends in water quality were determined for the same period. All 13 variables showed statistically significant linear regression relationships with values of the Southern Oscillation Index (SOI). The strongest relationships were for water temperature (mean R²= 0.20), dissolved reactive phosphorus (0.18), and oxidized nitrogen (0.17). The association with SOI varied by climate region. The observed patterns were generally consistent with known ENSO effects on New Zealand rainfall and air temperature. Trends in water quality variables for the periods 1989 through 1993, 1994 through 1998, and 1989 through 1998 were reasonably consistent with trends in SOI, even when the influence of river flow was removed from the data. This suggests that SOI effects on water quality are not necessarily a direct consequence of changes in flow associated with rainfall variation. In addition, both Baseline (32 upstream) and Impact (45 downstream) sites showed similar trends, indicating that changes in management were not directly responsible. We conclude that interpretation of long term water quality datasets in rivers requires that climate variability be fully acknowledged and dealt with explicitly in trend analyses.     

NATURWISSENSCHAFTEN AKTUELL

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控制卡塔尔居民生活用水量:评价

卡塔尔由于社会经济高速发展,人口大量增加,水资源存在严重问题.市政给水依靠高成本和不可持续的海水淡化,而对用水几乎没有限制,卡塔尔本国居民不用付水费,外国移居者付补助性的水费--大约1/3的成本费用,因此人们很少意识到水的真正成本,用水极其浪费.这篇文章讨论的是卡塔尔的用水趋势及与可持续用水有关的问题.一个针对卡塔尔社会各阶层的问卷调查了人们对水的意识和态度,结果显示,原有为了控制用水量而做的努力,如提高意识宣传活动、法律上的限制及水费是无效的.问卷评价了对限制用水可采取的措施的反应,其中有提高公众意识、使用法律措施和提高水费,从中提出一系列改变政策的建议,促使卡塔尔给水工业进入可持续发展阶段.     

Drugs from marine organisms

A modern approach to the search for biologically active substances of potential therapeutic use isolated from marine organisms is illustrated by a presentation of the multidisciplinary project pursued by the Roche Research Institute of Marine Pharmacology near Sydney, Australia. This specialized insitute is part of the world-wide research endeavour of our company and has now been in operation for five years. Following a brief outline of the technical functions the main scientific achievements published by the scientists of the institute are reviewed. This institute is, to our knowledge, the only one of its kind in private industry and we have attempted to demonstrate how its activities should be viewed in the overall context of today's drug or product development.