Seasonal Changes in the Plant Growth-Inhibitory Effects of Rosemary Leaves on Lettuce Seedlings
Kwame Sarpong Appiah,
Richard Ansong Omari,
Siaw Onwona-Agyeman,
Christiana Adukwei Amoatey,
John Ofosu-Anim,
Abderrazak Smaoui,
Abdelkarim Ben Arfa,
Yoko Suzuki,
Yosei Oikawa,
Shin Okazaki,
Keisuke Katsura,
Hiroko Isoda,
Kiyokazu Kawada,
Yoshiharu Fujii
Affiliations
Kwame Sarpong Appiah
Department of International Innovative Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Richard Ansong Omari
Leibniz Centre for Agricultural Landscape Research, Institute of Land Use Systems, Eberswalder Str. 84, 15374 Muencheberg, Germany
Siaw Onwona-Agyeman
Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Christiana Adukwei Amoatey
Department of Crop Science, College of Basic and Applied Science, University of Ghana, Legon, Accra P.O. Box LG 44, Ghana
John Ofosu-Anim
School of Architecture and Science, Central University, Tema P.O. Box 2305, Ghana
Abderrazak Smaoui
Centre of Biotechnology of Borj Cédria, BP 901 Hammam-Lif, Borj Cedria 2025, Tunisia
Abdelkarim Ben Arfa
L’Institut des Régions Arides, Route du Djorf Km 22.5, Médenine 4119, Tunisia
Yoko Suzuki
Aromatic Repos, AHOLA, A2 Soleil Jiyugaoka, 1-21-3, Jiyugaoka, Meguro 152-0035, Tokyo, Japan
Yosei Oikawa
Department of International Innovative Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Shin Okazaki
Department of International Innovative Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Keisuke Katsura
Department of International Innovative Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Hiroko Isoda
School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Ibaraki, Japan
Kiyokazu Kawada
School of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba 305-8572, Ibaraki, Japan
Yoshiharu Fujii
Department of International Innovative Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Tokyo, Japan
Plant biodiversity has been studied to explore allelopathic species for the sustainable management of weeds to reduce the reliance on synthetic herbicides. Rosemary (Rosmarinus officinalis L., syn Salvia rosmarinus Spenn.), was found to have plant growth-inhibitory effects, and carnosic acid was reported as an allelochemical in the plant. In this study, the effects of seasonal variation (2011–2012) on the carnosic acid concentration and phytotoxicity of rosemary leaves from two locations in Tunisia (Fahs and Matmata) were investigated. The carnosic acid concentration in rosemary leaves was determined by HPLC, and lettuce (Lactuca sativa L.) was used as the receptor plant in the phytotoxicity bioassay. The highest carnosic acid concentration was found in rosemary samples collected in June 2011, which also had the highest inhibitory activity. Furthermore, a significant inverse correlation (r = −0.529; p < 0.01) was found between the inhibitory activity on lettuce hypocotyl and the carnosic acid concentration in rosemary leaves. Both temperature and elevation had a significant positive correlation with carnosic acid concentration, while rainfall showed a negative correlation. The results showed that the inhibitory effects of rosemary leaf samples collected in summer was highest due to their high carnosic acid concentration. The phytotoxicity of rosemary needs to be studied over time to determine if it varies by season under field conditions.
