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Effects of ultraviolet‐C radiation on net photosynthesis, transpiration and dark respiration of Spathiphyllum wallisii

1984; Wiley; Volume: 60; Issue: 2 Linguagem: Inglês

10.1111/j.1399-3054.1984.tb04563.x

1399-3054

N. S. Murali, Henrik Saxe,

Lichen and fungal ecology

Electric arc welding was suspected to have damaged about 25000 potted Spathiphyllum wallisii plants in a commercial greenhouse. Therefore, the effects of UV-C radiation, phytotoxic gases and smoke particles on some basic physiological processes and on growth of Spathiphyllum plants were investigated in a controlled environment. The phytotoxic gases (NO, NO2, O3), separately and in combination, were harmless at exposure concentrations (2 mg m−3) well above incident levels, for several hours. The smoke particles, mainly ZnO, Fe2O3 and MnO, did not disturb the root environment and plant growth, even at 25 g m−2, which is approximately 400 times the calculated dose after the adverse incident. UV-C radiation from electric welding significantly reduced photosynthesis and transpiration shortly after exposure at 1 m (80 μW cm−2 nm−1 at 254 nm), while dark respiration was significantly increased. Effects at 3 m were less pronounced. The effect persisted for 2–4 days, after which recovery was complete. Further experiments with continuous measurement of gas exchange in whole plants confirmed that short-term UV-C radiation (Philips 30W germicidal tubes) dramatically affects photosynthesis, dark respiration and transpiration. Plants irradiated with more than 10 μW cm−2 nm−1 at 254 nm did not recover completely within the week of the experiments. The immediate effects of UV-C on photosynthesis is caused by stomatal closure. However, most effects are transient, and electric are welding does not appear to have caused the investigated damage.