Variation in CO2 assimilation rate induced by simulated dew waters with different sources of hydroxyl radical (*OH) on the needle surfaces of Japanese red pine (Pinus densifora Sieb. et Zucc.).
The hydroxyl radical (*OH) is generated in polluted dew on the needle surfaces of Japanese red pine (Pinus densiflora Sieb. et Zucc.). This free radical, which is a potent oxidant, is assumed to be a cause of ecophysiological disorders of declining trees on the urban-facing side of Mt. Gokurakuji, western Japan. Mists of *OH-generating N(III) (HNO2 and NO2-) and HOOH + Fe + oxalate solutions (50 and 100 microM, pH 5.1-5.4) simulating the dew water were applied to the foliage of pine seedlings grown in open-top chambers in the early morning. Needles treated with 100 microM N(III) tended to have a greater maximum CO2 assimilation rate (Amax), a greater stomatal conductance (g(s)) and a greater needle nitrogen content (Nneedle), suggesting that N(III) mist acts as a fertilizer rather than as a phytotoxin. On the other hand, needles treated with 100 microM HOOH + Fe + oxalate solution showed the smallest Amax, g(s), and Nneedle, suggesting that the combination of HOOH + Fe + oxalate caused a decrease in needle productivity. The effects of HOOH + Fe + oxalate mist on pine needles were very similar to the symptoms of declining trees at Mt. Gokurakuji.
Kobayashi
T
T
Japan Science and Technology Corporation (CREST), Center for Forest Decline Studies, Hiroshima Technoplaza, Higashi-Hiroshima. eco@pop.lowtem.hokudai.ac.jp
Natanani
N
N
Hirakawa
T
T
Suzuki
M
M
Miyake
T
T
Chiwa
M
M
Yuhara
T
T
Hashimoto
N
N
Inoue
K
K
Yamamura
K
K
Agus
N
N
Sinogaya
J R
JR
Nakane
K
K
Kume
A
A
Arakaki
T
T
Sakugawa
H
H
D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D002947:Cities; D017665:Hydroxyl Radical / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D009584:Nitrogen / Q000378:metabolism; D010070:Oxalates / Q000737:chemistry; D010788:Photosynthesis / Q000502:physiology*; D028223:Pinus / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry; D011157:Population Dynamics; D014867:Water / Q000737:chemistry
D010070:Oxalates; D014867:Water; D002245:Carbon Dioxide; D017665:Hydroxyl Radical; D007501:Iron; D009584:Nitrogen