Influência da luz sobre o crescimento e a produção de biomassa de Ruppia maritima L. em cultivo experimental

Abstract

Influência da luz sobre o crescimento e a produção de biomassa deRuppia maritima L. em cultivo experimental novas folhas produzidas foi determinada e a formação de folhas, raízes e "ramets" registrada diariamente. As respostas de crescimento de R. maritima variaram em função dos níveis de irradiância, durante as condições de cultivo experimental, com as plantas apresentando diferentes estratégias de adaptação aos diferentes regimes de luz testados. Em irradiância de 40 µmol m -2 s -1 , a longevidade (57,7 ± 2,7 dias) e o comprimento final das folhas (11,5 ± 0,3cm) foram maiores, embora a biomassa aérea e a taxa de crescimento específico das folhas tenham sido menores. Maiores irradiâncias levaram à maior produção de folhas, raízes, "ramets" e ramificações. Os resultados obtidos mostram que R. maritima apresenta melhor crescimento em ambientes com maiores intensidades luminosas e possui capacidade de ajustar suas características demográficas e respostas de crescimento a diferentes condições de luminosidade do ambiente Palavras-chave : Ruppia maritima, crescimento, biomassa, longevidade das folhas, intensidade luminosa. ABSTRACT -(Influence of light regimes on growth and biomass production of Ruppia maritima L. under controlled culture conditions).The effect of different light regimes on growth of plants of Ruppia maritima plants was assessed at irradiance levels of 40, 200 and 400 µmol m -2 s -1 , for 40 days. The longevity of newborn leaves was determined and the formation of leaves, roots and ramets was recorded daily. The growth response of R. maritima varied as a function of irradiance levels during experimental culture conditions, and plants showed different strategies of adapting to the different light regimes tested. At irradiance of 40 µmol m -2 s -1 , longevity (57.7 ± 2.7 days) and final leaf length (11.5 ± 0.3cm) were greater, but aerial biomass and specific growth rate of the leaves were lower. Higher levels of irradiance caused higher production of leaves, roots, ramets and ramifications. The results showed that R. maritima grows better at higher light intensities, and can adjust demographic characteristics and growth to different light conditions in the environment.

Using a toxicity test with Ruppia maritima (Linnaeus) to assess the effects of Roundup

“…Colares and Seeliger (2006) demonstrated the viability of raising healthy R. maritima specimens under laboratory conditions; however, these researchers grew this organism from seeds collected from southern Brazil seagrass meadow. The endpoints selected in this work are methodologically simple, not timeand material-consuming, and reliable to measure in a minimally equipped laboratory.…”

“…According to Colares and Seeliger (2006), R. maritima can adjust its demographics and growth depending on the lighting conditions. In this study, although the experiments were conducted in the presence of moderate artificial light (200 lmol m À2 s À1 ), this condition coincides with the light intensity irradiance at which this species exhibits a higher specific growth rate (Colares and Seeliger, 2006). Thus, we hypothesize that the results obtained are related to the action of glyphosate on plant development and not the lighting conditions at which the experiments were conducted.…”

“…maritima has been cited as a species of easy cultivation and maintenance in controlled laboratory conditions (Koch and Dawes, 1991;Colares and Seeliger, 2006). Laboratory experiments allow manipulation of various factors and determining their effects on the physiology and ecology of the species (Colares and Seeliger, 2006), as well as sensitivity or resistance of the species to the presence of toxic contaminants. Thus, the aim of the present work was to verify the acute effects of the formulated herbicide Roundup on the non-target specie R. maritima under laboratory conditions.…”

Seagrass and Submerged Aquatic Vegetation (VAS) Habitats off the Coast of Brazil: state of knowledge, conservation and main threats

“…The development of seagrass meadows in the Patos Lagoon, their variability and the equilibrium among plant and algal populations are highly dependent on hydrodynamics, particularly on the critical initial stages (COPERTINO; SEELIGER, 2010). When water and sediment movements are moderate (usually in late spring and throughout the summer), light, temperature and salinity enhance the growth rates, biomass allocation and flower production (KOCH; SEELIGER, 1989;SILVA;ASMUS, 2001;SEELIGER, 2006). Due to this synergistic effect, seagrass growth is concentrated in the spring and summer with meadows decaying or disappearing in the winter.…”

Estrutura foliar de curauá em diferentes intensidades de radiação fotossinteticamente ativa

“…As fibras vegetais são úteis na indústria automobilística, para o revestimento interno de automóveis, ônibus e caminhões, e na construção civil (Mothé & Araújo, 2004 Em sistemas agroflorestais, as plantas de porte mais baixo podem estar submetidas a condições sombreadas, em que as plantas apresentam respostas que podem variar com a maturidade e com a espécie, e com os impactos causados por fatores como: umidade, temperatura, radiação solar (Santos & Paiva, 2002). Assim, as irradiâncias baixas tendem a aumentar o tamanho do caule por unidade de peso e formar folhas maiores, porém mais finas (Poorter, 1999;Colares & Seeliger, 2006), enquanto as plantas que crescem a plena luz, em geral, apresentam folhas mais espessas e menor área foliar (Hao et al, 2000).…”