Effects of ultraviolet-B irradiance on soybean. V. The dependence of plant sensitivity on the photosynthetic photon flux density during and after leaf expansion [Glycine max, role of anatomical and morphological difference and physiological and biochemical processes]

• Published in: Plant physiology (Bethesda) 1984-03, Vol.74 (3), p.475-480
• Main Authors: Mirecki, R M, Teramura, A H
• Format: Article
• Language: English
• Subjects: Glycine max; Irradiance; Irradiation; Leaves; Ozone; Photosynthesis; Plants; protons; Radiation damage; Radiation tolerance; Soybeans; Transpiration; U.V. radiation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.74.3.475

Soybeans (Glycine max [L.] Merr. cv Essex) were grown in a greenhouse, and the first trifoliate leaf was either allowed to expand under a high photosynthetic photon flux density (PPFD) (1.4 millimoles per square meter per second) or a low PPFD (0.8 millimoles per square meter per second). After full leaf expansion, plants from each treatment were placed into a factorial design experiment with two levels of ultraviolet-B (UV-B) radiation (0 and 80 milliwatts per square meter biologically effective UV-B) and two levels of concomitant PPFD (0.8 and 1.4 millimoles per square meter per second) resulting in a total of eight treatments. Measurements of net photosynthesis and the associated diffusion conductances, ribulose-1,5-bisphosphate carboxylase activity, chlorophyll and flavonoid concentrations, and leaf anatomy were examined for all treatments. Leaves expanded in the high PPFD were unaffected by UV-B radiation while those expanded in the low PPFD were sensitive to UV-B-induced damage. Likewise, plants which were UV-B irradiated concomitantly with the high PPFD were resistant to UV-B damage, while plants irradiated under the low PPFD were sensitive. The results of this study indicate that both anatomical/morphological and physiological/biochemical factors contribute toward plant sensitivity to UV-B radiation.