Fotossíntese de espécies de Anibae em resposta à exposição a ambientes contrastantes de luz

Abstract

ResumoFotossíntese de espécies de Anibae em resposta à exposição a ambientes contrastantes de luz. Características ecofisiológicas e o ambiente de luz têm implicações sobre o estabelecimento de plantios florestais. O objetivo desse estudo foi investigar a fotossíntese de Aniba canelilla e A. rosaeodora em resposta à disponibilidade de luz no campo. As trocas gasosas, conteúdo de clorofilas (ICC) e desempenho fotoquímico (F V /F M ) foram medidos em folhas aclimatadas (sombra durante 300 dias), a pleno sol (28 dias) e novamente à sombra durante 28 dias. A fotossíntese, ICC e F V /F M de A. canelilla e A. rosaeodora foram afetadas negativamente a pleno sol, mas se recuperaram quando submetidas à sombra. A fotossíntese, ICC e F V /F M foram duas vezes superiores nas plantas de sombra. Aniba rosaeodora apresentou desempenho fotossintético duas vezes superior a A. canelilla. As diferenças nas respostas fotossintéticas à luz sugerem que as espécies poderiam ocupar "nichos" de sucessão diferentes em plantios de enriquecimento e, a plasticidade (mediada pela recuperação) implica aclimatação em ambientes de luz variável. O fato das espécies de Anibae estudadas possuírem diferenças de plasticidade para luz deve ser visto com cautela para sugerir plantios convencionais, mas reforça a indicação para plantios de enriquecimento em sítios florestais com variações na disponibilidade de luz. Palavras-chave: Aniba canelilla, Aniba rosaeodora, fluorescência da clorofila a, plantios florestais, trocas gasosas. AbstractPhotosynthesis of species of Anibae in response to the exposure to contrasting light environments. Ecophysiological traits and the light environment have implications for the establishment of forest plantations. The aim of this study was to investigate the photosynthetic activity of Aniba canelilla and A. rosaeodora in response to changes in the availability of light in the field. Gas exchange, content of chlorophylls (ICC) and photochemical performance (F V /F M ) were measured in leaves acclimated in the shade during 300 days, after in the full sun (28 days) and again in the shade by 28 days. The photosynthesis, ICC and F V /F M of A. canelilla and A. rosaeodora were negatively affected in full sunlight, but the plants recovered when submitted to shade. Photosynthesis, ICC and F V /F M were twice as high in shade plants. Aniba rosaeodora presented photosynthetic performance twice higher than A. canelilla. Differences in photosynthetic responses to light suggest that species could occupy different succession "niches" in enrichment plantation, and plasticity (recovery-mediated) implies acclimatization under variable light environments. The fact that the studied species of Anibae have differences in plasticity for light should be viewed with caution to suggest conventional plantations, but it reinforce the indication for enrichment plantations in forest sites with variations in the availability of light.

Growth inhibition of sourgrass as a function of period of darkness after diquat application

“…In addition to the stress caused by the action of the herbicide, plants are also subjected to stress due to excess light, called photoinhibition, in which the energy produced cannot be dissipated, which results in the accumulation of ROS (Lima-Melo et al 2019). The energy overload in the photosystems due to the high luminous intensity reduces photosynthesis (Blind et al 2018). However, photosynthetic rate evaluations were carried out the day after the application (from 7:00 a.m.), enabling recovery of photosynthetic activity in plants without diquat application, characterized as dynamic photoinhibition (Guidi et al 2019).…”

Impact of phosphorus and luminosity on the propagation, photochemical reactions and quality of Lippia alba (Mill.) N.E.Br. seedlings

“…Higher photochemical indicators, especially the F v / F m ratio, with phosphorus result because P favors the speed of ATP synthesis, contributing to the export of protons to the chloroplast stroma and thylakoid lumen (Carstensen et al, 2018), favoring the maintenance of electron mobility in PS II. Increasing F 0 / F v can be a photoprotective mechanism of the photosynthetic apparatus for excessive incident radiation (Blind et al, 2018), i.e. a greater use of electrons produced as a result of higher efficiency in absorbed energy conversion (F v /F 0 ), regardless of the shading level during this period (60 DAB) (Tab.…”