title: Detoxification of phytotoxic compounds by TiO2 photocatalysis in a recycling hydroponic cultivation system of asparagus.
abstract: TiO 2 photocatalytic decomposition and detoxification of phytotoxic compounds released by the roots of asparagus ( Asparagus officinalis L.) were investigated from the viewpoint of conservation-oriented cultivation. The phytotoxically active fraction was extracted either from dried asparagus roots or from the recycled nutrient solution of an asparagus hydroponic cultivation system. We found that the phytotoxic activity gradually decreased in the fraction with TiO 2 powder under irradiation with ultraviolet (UV) light at an intensity of 1.0 mW/cm (2). The growth of asparagus plants under actual cultivation conditions was also investigated by comparing asparagus grown in a hydroponic system where recycled waste nutrient solution was photocatalytically treated with solar light and a system with untreated recycled waste nutrient solution. The results showed, as measured by growth indices such as stem length and stem thickness, that asparagus growth in the photocatalytically treated system was superior to the untreated one. Furthermore, the yield of asparagus spears was 1.6-fold greater in the photocatalytically treated system, demonstrating the detoxification effect on the phytotoxic compounds and also the killing effect on pathogenic microorganisms.
authors.affiliation: Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Japan.
authors.forename: Kayano
authors.initials: K
authors.lastname: Sunada
authors.forename: Xin Geng
authors.initials: XG
authors.lastname: Ding
authors.forename: Melia Sandya
authors.initials: MS
authors.lastname: Utami
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kawashima
authors.forename: Yoko
authors.initials: Y
authors.lastname: Miyama
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Hashimoto
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity*; D027761:Asparagus Plant / Q000254:growth & development / Q000378:metabolism*; D002384:Catalysis; D003247:Conservation of Natural Resources; D018527:Hydroponics / Q000379:methods*; D010777:Photochemistry; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism*; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D015102:3,4-Dihydroxyphenylacetic Acid; C009495:titanium dioxide; D014025:Titanium