Clorofilas e antocianinas não competem por luz sob condição de sombra
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Data
2020-02-14
Autores
Cardoso, Ana Carolina Roque
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Universidade Estadual Paulista (Unesp)
Resumo
As plantas são responsáveis pela introdução de energia nos grandes ciclos biogeoquímicos do globo terrestre. Assim é importante a compreensão das respostas vegetais em relação às mudanças na intensidade da luz. Por isso, a hipótese do presente trabalho é que as clorofilas e antocianinas não competem por luz em condição limitante de luz. O objetivo deste trabalho foi verificar se as clorofilas e antocianinas não competem por luz, em condição de sombra. Para isso foram utilizadas como modelo de estudo duas variedades de Solenostemon scutellarioides (L.) Codd, popularmente conhecidas como coleus, as quais apresentavam folhas acumuladoras de antocianinas ou apenas clorofiladas. Estas, foram cultivadas em duas condições de luz (sombra e sol) durante o período de trinta dias. Para a condição de sombra, as variedades permaneceram sob vegetação arbórea com média de 80 µmol m-2 s-1 de fluência luminosa, enquanto a média de fluência sob condição de sol foi de 1300 µmol m-2 s-1. Quanto as análises realizadas, as antocianinas influenciaram os parâmetros (taxa fotossintética, ETRmax, fv/fm e teores de pigmentos) porém, os resultados indicaram que o fator luz, foi decisivo para o maior crescimento das plantas crescidas na condição de sol, independentemente das variedades, com ou sem acúmulo de antocianinas. Em relação a competição por luz na condição de sombra, as antocianinas estabelecem um filtro que dificulta a passagem dos comprimentos de onda para as clorofilas, principalmente em condições limitantes, alterando tanto a quantidade, como a qualidade de luz incidente nos cloroplastos. Por isso, os menores valores nos parâmetros avaliados foram observados em condição de sombra para coleus variegado. Entretanto, as clorofilas e antocianinas apresentam picos de absorção diferentes, não competindo por luz.
Plants are responsible for introducing energy into the great biogeochemical cycles of the globe. Thus, it is important to understand plant responses to changes in light intensity. Therefore, the hypothesis of the present work is that chlorophylls and anthocyanins do not compete for light in a light limiting condition. The objective of this work was to verify if chlorophylls and anthocyanins do not compete for light, in a shade condition. For this purpose, two varieties of Solenostemon scutellarioides (L.) Codd, popularly known as coleus, were used as study models, which presented anthocyanin accumulating leaves or just chlorophylls. These were grown in two light conditions (shade and sun) during the period of thirty days. For the shade condition, the varieties remained under tree vegetation with an average of 80 µmol m-2 s-1, while the average fluency under sunny conditions was 1300 µmol m-2 s-1. As for the analyzes carried out, the anthocyanins influenced the parameters (photosynthetic rate, ETRmax, fv/fm and pigment levels), however, the results indicated that the light factor was decisive for the greater growth of plants grown in the sun condition, regardless of varieties, with or without anthocyanin accumulation. In relation to competition for light in the shade condition, anthocyanins establish a filter that hinders the passage of wavelengths to chlorophylls, especially in limiting conditions, changing both the quantity and the quality of light incident on chloroplasts. Therefore, the lowest values in the evaluated parameters were observed in the shade condition for variegated coleus. However, chlorophylls and anthocyanins show different absorption peaks, not competing for light.
Plants are responsible for introducing energy into the great biogeochemical cycles of the globe. Thus, it is important to understand plant responses to changes in light intensity. Therefore, the hypothesis of the present work is that chlorophylls and anthocyanins do not compete for light in a light limiting condition. The objective of this work was to verify if chlorophylls and anthocyanins do not compete for light, in a shade condition. For this purpose, two varieties of Solenostemon scutellarioides (L.) Codd, popularly known as coleus, were used as study models, which presented anthocyanin accumulating leaves or just chlorophylls. These were grown in two light conditions (shade and sun) during the period of thirty days. For the shade condition, the varieties remained under tree vegetation with an average of 80 µmol m-2 s-1, while the average fluency under sunny conditions was 1300 µmol m-2 s-1. As for the analyzes carried out, the anthocyanins influenced the parameters (photosynthetic rate, ETRmax, fv/fm and pigment levels), however, the results indicated that the light factor was decisive for the greater growth of plants grown in the sun condition, regardless of varieties, with or without anthocyanin accumulation. In relation to competition for light in the shade condition, anthocyanins establish a filter that hinders the passage of wavelengths to chlorophylls, especially in limiting conditions, changing both the quantity and the quality of light incident on chloroplasts. Therefore, the lowest values in the evaluated parameters were observed in the shade condition for variegated coleus. However, chlorophylls and anthocyanins show different absorption peaks, not competing for light.
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Palavras-chave
Antocianina, Clorofila, Competição, Crescimento, Sombra, Anthocyanin, Chlorophyll, Competition, Growth, Shade