Ozone impairs autumnal resorption of nitrogen from birch (Betula pendula) leaves, causing an increase in whole-tree nitrogen loss through litter fall.

Saplings of one half-sib family of birch, Betula pendula Roth, were exposed to three ozone concentrations (non-filtered air (NF); non-filtered air + 10-20 nmol O(3) mol(-1) (NF+); non-filtered air + 40-60 nmol O(3) mol(-1) (NF++)) in open-top chambers during two growing seasons from 1997 to 1998. Shed leaves were collected regularly during both growing seasons and, in 1998, the dry mass (DM) and nitrogen (N) concentrations ([N]) of the shed leaves were measured to quantify the total amount of N lost through litter fall. Dry mass and [N] were also determined in mid-August for attached, mature and non-senescent leaves, in order to estimate autumnal leaf N resorption efficiency and proportional leaf DM decrease.

Ozone-induced changes in the chloroplast structure of conifer needles, and their use in ozone diagnostics.

Ozone induces characteristic symptoms in the chloroplasts of the needles of several coniferous species. Chloroplasts are (1) reduced in size and (2) the stroma is electron dense. Moreover, (3) these chloroplast alterations are more pronounced in the outer mesophyll cell layers and in the upper side of the needle compared to the inner layers and lower side.

Tropospheric ozone decreases biomass production in radish plants (Raphanus sativus) grown in rural south-west Sweden.

Potted plants of radish (Raphanus sativus L., cv. Cherry Belle) were grown in the ambient air for 5 weeks, with or without the application of a soil drench of the anti-ozonant ethylenediurea (EDU).

An ozone flux-response relationship for wheat.

Six open-top chamber experiments with field-grown wheat Triticum aestivum L. (five with spring wheat and one with winter wheat) were combined to test which of the two ozone exposure indices, AOT40 and CFO(3), that provided the most consistent relationship between relative yield loss and ozone exposure. AOT40 is the accumulated exposure over a threshold ozone concentration of 40 nl l(-1), while CFO(3) is the cumulative flux of ozone (uptake) to the flag leaves.

A cumulative ozone uptake-response relationship for the growth of Norway spruce saplings.

Norway spruce saplings [Picea abies (L.) Karst.] were exposed during four growing seasons to different ozone treatments in open-top chambers: charcoal filtered air (CF), non-filtered air (NF) and non-filtered air with extra ozone (NF+, 1.

The use of light and electron microscopy to assess the impact of ozone on Norway spruce needles.

Light (LM) and transmission electron (TEM) microscopy were used to study previously specified ozone symptoms in the foliage of Norway spruce. The three youngest green needle generations from twenty mature trees in two stands on sites of different soil fertility at Asa, southern Sweden, were sampled in 1999. The critical dose of ozone, expressed as AOT40, was 6,362 ppb.

Cell structural changes in the needles of Norway spruce exposed to long-term ozone and drought.

Effects of ozone and/or drought on Norway spruce needles were studied using light microscopy and electron microscopy. Saplings were exposed to ozone in open-top chambers during 1992-1995 and also to drought in the late summers of 1993-1995. Samples from current and previous year needles were collected five times during 1995.

The effects of tropospheric ozone and elevated carbon dioxide on potato (Solanum tuberosum L. cv. Bintje) growth and yield.

An open-top chamber experiment with field grown potato (Solanum tuberosum L. cv. Bintje) was performed in the south-west of Sweden in 1998.

Impact of ozone on the growth of birch (Betula pendula) saplings.

Saplings of one half-sib family of birch, Betula pendula, were exposed to three levels of ozone in open-top chambers (OTCs) during two growing seasons 1997-1998. The ozone treatments were non-filtered air (NF, accumulated daylight AOT40 over the two growing seasons of 3.0 l l-1 h), non-filtered air with extra ozone (NF+, accumulated daylight AOT40 of 27.

Impact of ozone and reduced water supply on the biomass accumulation of Norway spruce saplings.

Norway spruce saplings [Picea abies (L.) Karst.] were exposed during four growing seasons to two different ozone treatments in open-top chambers: charcoal filtered air (CF), and non-filtered air with extra ozone (NF+, 1.

Impact of four years exposure to different levels of ozone, phosphorus and drought on chlorophyll, mineral nutrients, and stem volume of Norway spruce, Picea abies.

Saplings of one clone of Norway spruce, Picea abies (L.) Karst, were planted in 120 l pots in 1991 and exposed to three levels of ozone, two levels of phosphorus and two levels of water supply in 42 open-top chambers (OTCs), during 1992-1996. The effects of pots and OTCs were also tested.

Clover as an indicator plant for phytotoxic ozone concentrations: visible injury in relation to species, leaf age and exposure dynamics.

Visible ozone injury on leaves of three clover species was investigated in relation to species, leaf age and exposure dynamics. It was shown that ozone episodes in south-west Sweden cause visible injury to subterranean clover (Trifolium subterraneum L.), white clover (Trifolium repens L.

Exposure of oats, Avena sativa L., to filtered and unfiltered air in open-top chambers: effects on grain yield and quality.

Field grown oats, Avena sativa L. cv Vital, were exposed to filtered and unfiltered air from anthesis until harvest in open-top chambers at a site in south-west Sweden. Ambient plots were used to study the influence of the chamber itself.

Long-term exposure of Norway spruce, Picea abies (L.) Karst., to ozone in open-top chambers: IV. Effects on the stomatal and non-stomatal limitation of photosynthesis and on the carboxylation efficiency.

Rates of photosynthesis at different concentrations of CO (0-1850 μmol mol ) were measured using one clone of Norway spruce, Picea abies (L.) Karst. exposed to three different concentrations of ozone for four seasons (1985-8) in open-top chambers.

Long-term exposure of Norway spruce, Picea abies (L.) Karst., to ozone in opentop chambers: III. Effects on the light response of net photosynthesis in shoots of different ages.

Rates of photosynthesis at different photosynthetic photon flux densities (PPFD; 0-1530 μmol m s ) were measured on three shoot age classes of one clone of Norway spruce, Picea abies (L.) Karst. exposed to three different concentrations of ozone for three seasons (1985-7) in open-top chambers.

Stromal low temperature compartment derived from the inner membrane of the chloroplast envelope.

Leaf discs of four dicotyledonous species, when incubated at temperatures of 4 to 18 degrees C (optimum at 12 degrees C) for 30 or 60 minutes, responded by accumulations of membranes in the chloroplast stroma in the space between the inner membrane of the envelope and the thylakoids. The accumulated membranes, here referred to as the low temperature compartment, were frequently continuous with the envelope membrane and exhibited kinetics of formation consistent with a derivation from the envelope. Results were similar for expanding leaves of garden pea (Pisum sativum), soybean (Glycine max), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum).

Yield and grain quality of spring wheat (Triticum aestivum L., cv. Drabant) exposed to different concentrations of ozone in open-top chambers.

Spring wheat (Triticum aestivum L., cv. Drabant) was exposed to different concentrations of ozone in open-top chambers for two growing seasons, 1987 and 1988, at a site located in south-west Sweden.

Long-term exposure of Norway spruce, Picea abies (L.) Karst., to ozone in open-top chambers: I. Effects on the capacity of net photosynthesis, dark respiration and leaf conductance of shoots of different ages.

Rates of net photosynthesis were measured on Norway spruce, Picea abies (L.) Karst. exposed to three different concentrations of ozone for three seasons (1985-7) in open-top chambers.

Long-term exposure of Norway spruce, Picea abies (L.) Karst., to ozone in open top chambers: II. Effects on the ultrastructure of needles.

One clone of spruce, Picea abies (L.) Karst., was exposed to different concentrations of ozone in open-top chambers for three seasons.

Localization of DNA in Mature and Young Wheat Chloroplasts Using the Fluorescent Probe 4'-6-Diamidino-2-phenylindole.

The spatial organization of chloroplast DNA in developing and dividing wheat chloroplasts was studied in the light microscope using the fluorescent probe 4'-6-diamidino-2-phenylindole, which binds specifically to DNA.The DNA of wheat chloroplasts was localized at the periphery of the plastid, frequently in a discrete band. No relocalization of the DNA was observed during plastid replication.

Comparative analyses of the effect of triacontanol on photosynthesis, photorespiration and growth of tomato (C3-plant) and maize (C 4-plant).

Tomato (C3-plants) and maize (C4-plants) were grown in a nutrient solution to which triacontanol was added twice a week. After about 4 weeks the triacontanol treatment caused a significant increase in the dry weight of the tomato plants. Leaf area and dry weight measurements of tomato leaves at different stages of development showed that the largest increase in growth was obtained when triacontanol treatment was initiated before bud formation.

Influence of Cell Age on Chlorophyll Formation in Light-grown and Etiolated Wheat Seedlings.

A method is described for relating the age of a cereal leaf cell to its distance from the leaf base. The rates of chlorophyll synthesis per plastid in the first leaf of light-grown and of greening etiolated seedlings of wheat (Triticum aestivum, var. Maris Dove) increase with cell age.

Chloroplast Division and DNA Synthesis in Light-grown Wheat Leaves.

Light-grown 7-day-old wheat seedlings (Triticum aestivum, var. Maris Dove) showed an increase of 200% in plastids per cell between 1.7 and 4.

Appearance and development of P700 oxidation and photosystem I activity in etio-chloroplasts prepared from greening barley leaves.

The development of photosystem I activity of plastids isolated from greening barley (Hordeum distichum, L.) leaves was studied. The electron transport activity in photosystem I was measured as anthraquinone-mediated oxygen uptake and as light induced absorbance changes of the reaction centre molecule P700.