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Growth and photosynthesis of virus‐infected and virus‐eradicated orchid plants exposed to different growth irradiances under natural tropical conditions
Author(s) -
He Jie,
Ouyang Wen,
Chia Tet Fatt
Publication year - 2004
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2004.00365.x
Subject(s) - photosynthesis , biology , botany , horticulture , chlorophyll , stomatal conductance , irradiance , sunlight , physics , quantum mechanics , astronomy
Responses of virus‐infected (VI) and virus‐eradicated (VE) Oncidium Gower Ramsey orchid plants grown under 30% of prevailing solar radiation and those transferred from 30 to 60% and 100% of prevailing solar radiation were studied under natural tropical conditions. Plants grown under 30% of prevailing solar radiation suffered lower leaf and floral production and reduced photosynthesis. When the irradiance was increased to 60% of prevailing solar radiation, enhancement of leaf and floral production and photosynthetic capacities were achieved. However, when the plants were transferred from 30 to 100% of prevailing solar radiation, the growth and photosynthetic capacities of the plants were significantly reduced. All plants exhibited a midday depression in photosynthetic CO 2 assimilation ( A ), stomatal conductance ( g s ) and F v / F m ratio . The degree of midday depression of these parameters was not only associated with high temperatures and high irradiances but also with virus infection. Midday F v / F m ratio depression indicated that dynamic photo‐inhibition occurred in all plants grown under all three light conditions. However, chronic photo‐inhibition, measured by pre‐dawn F v / F m ratio and chlorophyll content, occurred only in those plants transferred from 30 to 100% of prevailing solar radiation. Hence, it is concluded that the VI Oncidium Gower Ramsey was more susceptible to high irradiance than the VE plants.