|Induced photomorphogenesis by an altered R:FR light ratio in axenic Ruppia maritima L.|
Rose, C.D.; Durako, M.J. (1994). Induced photomorphogenesis by an altered R:FR light ratio in axenic Ruppia maritima L. Bot. Mar. 37(6): 531-535
In: Botanica Marina. Walter de Gruyter & Co: Berlin; New York. ISSN 0006-8055; e-ISSN 1437-4323, meer
Groei; Lichteffecten; Photosynthetic pigments; Plantenmorfologie; Zeegrassen; Ruppia maritima Linnaeus, 1753 [WoRMS]; Marien
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The morphology and growth of the submerged macrophyte Ruppia maritima L. in axenic cultures differed when the plants were exposed to light with similar photosynthetically active radiation levels (76-80 mu E/m-2/s-1 PAR) but with different red:far-red (R:FR) ratios. Plants irradiated with an R:FR ratio of 0.55 produced significantly fewer nodes and branches than did plants grown in an ambient R:FR ratio of 0.95. In contrast, biomass and internode lengths of the plants were the same after the two R:FR treatments, suggesting that the light treatments influenced qualitative rather than quantitative growth patterns. The R:FR ratio decreases in shallow aquatic habitats when red light is attenuated by photosynthetic pigments associated with phytoplankton, macroalgae, and submerged macrophyte leaf canopies. Understory plants generally respond to reduced R:FR ratios by modifying their growth so that they can escape shaded environments, thereby minimizing interspecific competition for light. Thus, the observed changes in growth patterns of Ruppia in response to qualitative changes in the light environment may have adaptive value for this species when it occurs as an understory plant in mixed-species seagrass beds.