Interactive effects of light and salinity stress on the growth,reproduction, and photosynthetic capabilities of<Emphasis Type="Italic">Vallisneria americana</Emphasis> (wild celery) |
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Authors: | Gail?T?French Email author" target="_blank">Kenneth?A?MooreEmail author |
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Institution: | (1) Pacific Northwest National Laboratory, Marine Sciences Laboratory, 1529 W. Sequim Bay Road, Sequim, WA 98382, USA;(2) Glacier Northwest, 5975 East Marginal Way South, Seattle, WA 98134, USA |
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Abstract: | The effects of light and salinity onVallisneria americana (wild celery) were studied in outdoor mesocosms for an entire growing season. Morphology, production, photosynthesis, and
reproductive output were monitored from sprouting of winter buds to plant senescence and subsequent winter bud formation under
four salinity (0, 5, 10, and 15 psu) and three light (2%, 8%, and 28% of surface irradiance) regines. Chlorophylla fluorescence was used to examine photochemical efficiency and relative electron transport rate. High salinity and low light
each stunted plant growth and reproduction. Production (biomass, rosette production, and leaf area index) was affected more
by salinity than by light, apparently because of morphological plasticity (increased leaf length and width), increased photosynthetic
efficiency, and increased chlorophyll concentrations under low light. Relative maximum electron transport rate (ETRmax) was highest in the 28% light treatment, indicating increased photosynthetic capacity. ETRmax was not related to salinity, suggesting that the detrimental effects of salinity on production were through decreased photochemical
efficiency and not decreased photosynthetic capacity. Light and salinity effects were interactive for measures of production,
with negative salinity effects most apparent under high light conditions, and light effects found primarily at low salinity
levels. For most production and morphology parameters, high light ameliorated salinity stress to a limited degree, but only
between the 0 and 5 psu regimes. Growth was generally minimal in all of the 10 and 15 psu treatments, regardless of light
level. Growth was also greatly reduced at 2% and 8% light. Flowering and winter bud production were impaired at 10 and 15
psu and at 2% and 8% light. Light requirements at 5 psu may be approximately 50% higher than at 0 psu. Because of the interaction
between salinity and light requirements for growth, effective management of SAV requires that growth requirements incorporate
the effects of combined stressors. |
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