Growth, biomass allocation and photosynthesis of Rolandra fruticosa (asteraceae) in response to shade

Crescimento, alocação de biomassa e fotossíntese de Rolandra fruticosa (asteraceae) em resposta ao sombreamento

Growth, biomass allocation and photosynthesis of Rolandra fruticosa (asteraceae) in response to shade

Crescimento, alocação de biomassa e fotossíntese de Rolandra fruticosa (asteraceae) em resposta ao sombreamento

Moacyr B. Dias-Filho^I; Aloisio F. Chagas Júnior^II

^IResearch agronomist, Ph.D., Lab. Ecofisiologia Vegetal, Embrapa Amazônia Oriental, Caixa Postal 48, CEP 66017-970, Belém-PA, Brazil, e-mail: [e-mail]. CNPq fellow

^IIGraduate Student, INPA, Manaus-AM, Brazil, Former PIBIC/CNPq fellow

ABSTRACT

The effects of shade on growth, biomass allocation patterns and photosynthetic response was examined for Rolandra fruticosa (L.) Kuntze, a common perennial weed shrub in cultivated pastures and agricultural areas of Brazilian Amazonia, for plants grown in full sunlight and those shaded to 30 % of full sunlight over a 34-d period. Specific leaf area and leaf area ratio were higher for shade plants during all the experimental period. Shade plants allocated significantly less biomass to root tissue than sun plants and relative growth rate was higher in sun plants. Sun leaves had significantly higher dark respiration and light saturated rates of photosynthesis than shade leaves. The apparent quantum efficiency was higher for shade leaves, while light compensation point was higher for sun leaves. These results are discussed in relation to their ecological and weed management implications.

Key words: Specific leaf area, leaf area ratio, growth analysis, tropics.

RESUMO

Estudou-se o efeito do sombreamento nocrescimento, alocação de carbono e respostas fotossintéticas de Rolandra fruticosa (L.) Kuntze, uma planta daninha de porte arbustivo, comum em áreas de pastagem e agrícolas da Amazônia Brasileira, submetida a condições de pleno sol e a 70 % de interceptação da luz solar, durante 34 dias. A área foliar específica e a razão de área foliar foram maiores nas plantas sombreadas durante todo o período experimental. Plantas sombreadas alocaram menor quantidade de biomassa para as raízes, quando comparadas às plantas de sol e a taxa de crescimento relativo foi maior para as plantas de sol. A respiração no escuro e a taxa de fotossíntese máxima foram maiores para as folhas de plantas não sombreadas. A eficiência quântica aparente foi maior para as folhas de plantas sombreadas, enquanto que o ponto de compensação de luz foi maior para folhas a pleno sol. Esses resultados são discutidos com relação as suas importâncias ecológica e de manejo.

Palavras chave: Área foliar específica, razão de área foliar, análise de crescimento, trópicos.

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LITERATURE CITED

Received for publication on 18/02/99 and in the revised form on 16/05/99.

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Publication Dates

• Publication in this collection
  04 May 2010
• Date of issue
  2000

History

• Accepted
  16 May 1999
• Received
  18 Feb 1999