Elevated CO boosts reproduction and alters selection in northern but not southern ecotypes of allergenic ragweed.

Premise Of The Study: Many plants increase reproduction in response to rising levels of atmospheric CO . However, environmental and genetic variation across heterogeneous landscapes can lead to intraspecific differences in the partitioning of CO -induced carbon gains to reproductive tissue relative to growth.

Methods: We measured the effects of rising atmospheric CO on biomass allocation in the allergenic plant Ambrosia artemisiifolia (common ragweed) across a geographic climate gradient.

Northern ragweed ecotypes flower earlier and longer in response to elevated CO2: what are you sneezing at?

Significant changes in plant phenology and flower production are predicted over the next century, but we know relatively little about geographic patterns of this response in many species, even those that potentially impact human wellbeing. We tested for variation in flowering responses of the allergenic plant, Ambrosia artemisiifolia (common ragweed). We grew plants originating from three latitudes in the Northeastern USA at experimental levels of CO2 (400, 600, and 800 µL L(-1)).

Projected carbon dioxide to increase grass pollen and allergen exposure despite higher ozone levels.

One expected effect of climate change on human health is increasing allergic and asthmatic symptoms through changes in pollen biology. Allergic diseases have a large impact on human health globally, with 10-30% of the population affected by allergic rhinitis and more than 300 million affected by asthma. Pollen from grass species, which are highly allergenic and occur worldwide, elicits allergic responses in 20% of the general population and 40% of atopic individuals.

Elevated night soil temperatures result in earlier incidence and increased extent of foliar ozone injury to common bean (Phaseolus vulgaris L.).

Elevated nighttime soil temperature (5 degrees C) increased bean seed germination and onset of foliar ozone injury.