Ethylenediurea (EDU) effects on Japanese larch: an one growing season experiment with simulated regenerating communities and a four growing season application to individual saplings

• Published in: Journal of forestry research 2021-10, Vol.32 (5), p.2047-2057
• Main Authors: Agathokleous, Evgenios, Kitao, Mitsutoshi, Wang, Xiaona, Mao, Qiaozhi, Harayama, Hisanori, Manning, William J., Koike, Takayoshi
• Format: Article
• Language: English
• Subjects: Biological monitoring; Biomedical and Life Sciences; Biomonitoring; Coniferous trees; Damage; Economic importance; Experiments; Exposure; Forestry; Growing season; Larix kaempferi; Leaves; Life Sciences; Northern Hemisphere; Original Paper; Regeneration; Research projects; Seasons; Seedlings
• ISSN: 1007-662X; 1993-0607
• DOI: 10.1007/s11676-020-01223-6

Japanese larch ( Larix kaempferi (Lamb.) Carr.) and its hybrid are economically important coniferous trees widely grown in the Northern Hemisphere. Ground-level ozone (O 3 ) concentrations have increased since the pre-industrial era, and research projects showed that Japanese larch is susceptible to elevated O 3 exposures. Therefore, methodologies are needed to (1) protect Japanese larch against O 3 damage and (2) conduct biomonitoring of O 3 in Japanese larch forests and, thus, monitor O 3 risks to Japanese larch. For the first time, this study evaluates whether the synthetic chemical ethylenediurea (EDU) can protect Japanese larch against O 3 damage, in two independent experiments. In the first experiment, seedling communities, simulating natural regeneration, were treated with EDU (0, 100, 200, and 400 mg L −1 ) and exposed to either ambient or elevated O 3 in a growing season. In the second experiment, individually-grown saplings were treated with EDU (0, 200 and 400 mg L −1 ) and exposed to ambient O 3 in two growing seasons and to elevated O 3 in the succeeding two growing seasons. The two experiments revealed that EDU concentrations of 200–400 mg L −1 could protect Japanese larch seedling communities and individual saplings against O 3 -induced inhibition of growth and productivity. However, EDU concentrations ≤ 200 mg L −1 did offer only partial protection when seedling communities were coping with higher level of O 3 -induced stress, and only 400 mg EDU L −1 fully protected communities under higher stress. Therefore, we conclude that among the concentrations tested the concentration offering maximum protection to Japanese larch plants under high competition and O 3 -induced stress is that of 400 mg EDU L −1 . The results of this study can provide a valuable resource of information for applied forestry in an O 3 -polluted world.