Efeito da inundação de longa duração sob o crescimento de Pouteria glomerata (Sapotaceae), uma arbórea da várzea da Amazônia Central

Abstract

RESUMOPara entender a ocorrência de P. glomerata na várzea amazônica, investigamos as respostas morfo-fisiológicas a longo período de inundação. Durante seis meses, plântulas de P. glomerata foram submetidas a dois tratamentos de inundação (parcial e total) para análise da assimilação fotossintética líquida (A), eficiência quântica do fotosistema II (referido como Fv/Fm), altura, número de folhas, diâmetro do colo do caule (DCC), área foliar e biomassa da planta. Encontramos um decréscimo da atividade de trocas gasosas, das taxas de crescimento e danos foliares com o aumento do nível de inundação. Após seis meses de experimento, a área foliar, a biomassa dos órgãos vegetativos (raiz, caule e folha) e a biomassa total das plântulas inundadas foram menores que das plântulas controle, plântulas não-inundadas. De acordo com o aumento do nível de inundação, a biomassa fotoassimilada foi alocada principalmente para o caule. Somente área foliar específica, razão raiz / parte aérea e massa seca de raiz não apresentaram diferenças entre os tratamentos. As plântulas totalmente inundadas foram fortemente comprometidas, demonstrando ser esta à condição mais crítica para a manutenção do metabolismo fisiológico. P. glomerata foi afetada pelo longo período de inundação, no entanto a espécie revela adaptações morfo-fisiologica que justifica a sua ocorrência em florestas de várzea. PALAVRAS-CHAVE:Assimilação fotossintética, eficiência quântica do fotossistema II, biomassa, tolerância e plasticidade fenotípica. Growth of Pouteria glomerata (Sapotaceae), a tree species from the Central Amazonian floodplain, under long-term flooding ABSTRACTTo understand the occurrence of P. glomerata in the Amazonian várzea we investigated the morpho-physiological responses to long-term flooding. Seedlings of P. glomerata were subjected to two flooding treatments (partial and total) for six months. Following flooding treatments, we examined light-saturated photosynthesis (A), the potential quantum yield of photosystem II (inferred as the Fv/Fm ratio), height, number of leaves (NF), stem diameter at the base of the plant (DCC), leaf area and plant biomass. We found a decrease in gas exchange parameters and growth rates, whereas leaf damage increased with flooding. After six months of flooding, leaf area, and the total plant biomass as well as the biomass of the vegetative organs (leaf, stem and root) were lower in flooded seedlings than in control, non-flooded plants. As flooding level increased assimilated carbon was mainly allocated to stems. However, flooding treatments had no significant effect on specific leaf area, the root/shoot ratio and dry mass of roots. Totally submerged roots of flooded seedlings were strongly affected, showing to be the most critical condition for maintenance of physiological metabolism. P. glomerata was affected by long-term flooding. Thus, P. glomerata exhibited adjusts morpho-fisiological which makes it possible for this species to occur in the Amazon floodplain forest.KEY WORDS: Photosynthetic assimilation, quantum...

Effects of flooding and shading on growth and gas exchange of Vochysia divergens Pohl (Vochysiaceae) of invasive species in the Brazilian Pantanal

“…Plants exposed to flooding have increased levels of abscisic acid (ABA) (Wilkinson and Davies, 2002), which causes a decline in g s (Holbrook et al, 2002) even without any apparent loss of turgor (Maurenza et al, 2009). Anaerobic production of ethanol and lactic acid (Crawford, 1992;Drew, 1997;Oliveira and Joly, 2010) can also lead to a reduction in xylem water potential and g s (Pezeshki et al, 1993;Herrera et al, 2010).…”

“…For example, plants invading areas subject to periodic flooding are exposed to extended periods of hypoxia and/or anoxia (Armstrong et al, 1994;Maurenza et al, 2009) and high concentrations of toxic products (McKee and McKevlin, 1993;Jackson and Colmer, 2005), and successful invaders must be able to tolerate widely fluctuating hydrological conditions. In contrast, riparian species invading drier upland areas must be able to tolerate periodic drought, and many successful invaders exhibit flexibility in root system morphology, which is critical for exploiting ephemeral and/or deep water reserves (Sala et al, 1996;Lite and Stromberg, 2005).…”

“…For example, the expansion of V. divergens is most rapid in highlight, grassland-dominated areas (Nunes da Cunha and Junk, 2004), but seedlings and saplings are often subjected to shading by canopy trees and/or bunch grasses during recruitment. Coupled with prolonged seasonal flooding, which can cause mortality in flood-sensitive tree species (Larcher, 1995) and a decline in the growth and gas exchange of flood-adapted tree species (Fernández et al, 1999;Mielke et al, 2003;Maurenza et al, 2009;Herrera et al, 2010;Oliveira and Joly, 2010), V. divergens seedlings and saplings are likely subjected to physiological stress as they invade these novel habitats.…”

Growth responses and accumulation of soluble sugars in Inga marginata Wild. (Fabaceae) subjected to flooding under contrasting light conditions

“…Other adaptations to flooded environments involve a reduction in the rate of respiration, accompanied by the accumulation of soluble sugars (Qin et al, 2013), and compensatory changes in metabolism associated with differential allocation of biomass (Maurenza et al, 2009). In the natural environment, plants face the combination of a number of factors that can be constraints to their growth or determine their occurrence.…”

Efeito do alagamento na germinação de sementes e no crescimento de plantas jovens de Genipa americana e Guazuma ulmifolia com ocorrência no Cerrado e na Amazônia

“…A tolerância ao estresse devido à privação de oxigênio pode variar de poucas horas a muitos dias, ou mesmo semanas, conforme a espécie, os órgãos afetados e estágio de desenvolvimento da planta (Vartapetian e Jackson, 1997). Dessa maneira, somente plantas que possuem eficientes adaptações para tolerar a submersão conseguem se estabelecer (Maurenza et al, 2009).…”