Life cycle of Egeria densa planch., an aquatic plant naturalized in Japan
1988; Elsevier BV; Volume: 30; Issue: 4 Linguagem: Inglês
10.1016/0304-3770(88)90070-8
ISSN1879-1522
AutoresToshihiro Haramoto, Isao Ikusima,
Tópico(s)Coastal wetland ecosystem dynamics
ResumoThe ecophysiological life cycle of Egeria densa Planch., in a lotic irrigation ditch was evaluated. Phenological and quantitative measurements were made from August 1984 to July 1985. Lateral shoots with roots developed and elongated to the surface of the water when the bottom-water temperature increased above c. 15°C. Root crown developed simultaneously as the plant biomass increased. Dense shoot crown was formed under the water surface after the shoot reached the water surface. Plant biomass had two maxima in August and December-January. The bimodal curve in plant biomass was caused by the difference of growth attributed to the winter-type and summer-type plants. Relative growth rate, in length, of summer-type plants occurred at an optimum temperature of 20.7°C in culture. The seasonal activity of photosynthesis and respiration was measured in March, August and December. The optimum temperature of net photosynthesis of the summer-type plants reached a high 35°C similar to that of the C4 plant. The compensation for light intensity at 35°C was 340 lux. Each photosynthesis-temperature curve suggested that Egeria had the ability to adapt to the seasonal changes in temperature in the natural habitat. The maximum starch concentrations reached 25.4% in the leaf and 22.6% in the stem in December. The shortage in the balance of organic matter for overwintering was found to be maintained by stored starch in the leaf and the stem.
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