Developmental and Structural Section
Lee, David , Edwards, Adrienne , Philippi, Tom , Richards, Jennifer .
Effects of Clipping and Shadeing on Shoot Growth in Eleocharis cellulosa Torr. (Cyperaceae).
ELEOCHARIS cellulosa Torr (Cyperaceae), a shallow water spikerush of Southeastern United States and the Caribbean (and common in the Everglades of south Florida), alters shoot height when growing in water of varying depths. This growth is controlled by the activity of a meristem at the base of each stem. We subjected individual plants to experiments of clipping of individual shoots, and of shading individual plants and shoots, to determine effects on shoot growth. When young shoots were clipped, and the tips were left open, shoots quickly died. However, when the cut tips were sealed the shoots elongated, particularly in younger shoots under deeper water conditions. Shaded plants (14 % of photosynthetically active radiation) produced taller shoots than clear plastic and open controls, and reduction in red:far-red quanta (R:FR) to 0.25 did not increase elongation compared to spectrally neutral shade (R:FR of 1.25). Young shoots (just emerging from the water) were more responsive to the shading and clipping treatments than older shoots. These shading and clipping responses are consistent with the deep water rice stem elongation model involving stem partial oxygen pressure affecting growth regulators, particularly gibberellins, because shading and clipping could alter oxygen concentrations in the Eleocharis stems. However, these shade responses could also be due to direct photoreception. The lack of elongation in individually shaded stems indicates that the site of such reception is not in individual stems, but at the base of the entire plant.
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1 - Florida International University, Deparment of Biological Sciences, 11200 SW 8th St., Miami, Florida, 33199, USA
2 - Illinois Natural History Survey, Center For Wildlife & Plant Ecology, 607 East Peabody Drive, Champaign, Illinois, 61820, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 303/Bell Memorial Union
Date: Wednesday, August 2nd, 2006
Time: 8:45 AM