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Photosynthetic characteristics of the submerged macrophyte Ceratophyllum demersum
Author(s) -
Best Elly P. H.
Publication year - 1986
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1986.tb03389.x
Subject(s) - ceratophyllum demersum , photosynthesis , dry weight , photorespiration , carbon fixation , botany , chlorophyll , biology , macrophyte , photosynthetic efficiency , dcmu , carbon dioxide , aquatic plant , horticulture , chemistry , photosystem ii , ecology
The photosynthetic and growth characteristics of Ceratophyllum demersum L. were investigated under laboratory conditions which simulated those encountered in the plants' normal environment. The carbon fixation rate of C. demersum measured with 14 C at light and carbon saturation at pH 8.0 was 4.48 mg C (g ash‐free dry weight) −1 h −1 . It was lower at pH 6.5 than at pH 8.0. The light use efficiencies in quiescent plants and actively growing plants were 6.3 and 8.7 × 10 −9 kg CO 2 J −1 , respectively, with corresponding maximum photosynthetic rates of 2.67 and 4.36 mg C (g ash‐free dry weight) −1 h −1 . Photorespiration in actively growing plants consumed 24% of the carbon fixed. Incubation with DCMU demonstrated that about one‐third was refixed. The optimum temperature for carbon fixation was 25°C. The C 3 ‐photosynthetic pathway was the main operational route as indicated by the early photosynthetic products (largely C 3 ‐acids) and the absence of Krantz anatomy and the chlorophyll a:b ratio (2.7). The maximum relative growth rates ranged from 0.025 to 0.041 g ash‐free dry weight (g ash‐free dry weight) −1 day −1 in the field (Lake Vechten, 1 to 3 m depth classes).