title: Allelochemical stress inhibits growth, leaf water relations, PSII photochemistry, non-photochemical fluorescence quenching, and heat energy dissipation in three C3 perennial species.
abstract: In this study, the effect of two allelochemicals, benzoxazolin-2(3H)-one (BOA) and cinnamic acid (CA), on different physiological and morphological characteristics of 1-month-old C(3) plant species (Dactylis glomerata, Lolium perenne, and Rumex acetosa) was analysed. BOA inhibited the shoot length of D. glomerata, L. perenne, and R. acetosa by 49%, 19%, and 19% of the control. The root length of D. glomerata, L. perenne, and R. acetosa growing in the presence of 1.5 mM BOA and CA was decreased compared with the control. Both allelochemicals (BOA, CA) inhibited leaf osmotic potential (LOP) in L. perenne and D. glomerata. In L. perenne, F(v)/F(m) decreased after treatment with BOA (1.5 mM) while CA (1.5 mM) also significantly reduced F(v)/F(m) in L. perenne. Both allelochemicals decreased ΦPSII in D. glomerata and L. perenne within 24 h of treatment, while in R. acetosa, ΦPSII levels decreased by 72 h following treatment with BOA and CA. There was a decrease in qP and NPQ on the first, fourth, fifth, and sixth days after treatment with BOA in D. glomerata, while both allelochemicals reduced the qP level in R. acetosa. There was a gradual decrease in the fraction of light absorbed by PSII allocated to PSII photochemistry (P) in R. acetosa treated with BOA and CA. The P values in D. glomerata were reduced by both allelochemicals and the portion of absorbed photon energy that was thermally dissipated (D) in D. glomerata and L. perenne was decreased by BOA and CA. Photon energy absorbed by PSII antennae and trapped by 'closed' PSII reaction centres (E) was decreased after CA exposure in D. glomerata. BOA and CA (1.5 mM concentration) decreased the leaf protein contents in all three perennial species. This study provides new understanding of the physiological and biochemical mechanisms of action of BOA and CA in one perennial dicotyledon and two perennial grasses. The acquisition of such knowledge may ultimately provide a rational and scientific basis for the design of safe and effective herbicides.
authors.affiliation: Department of Plant Biology and Soil Science, University of Vigo, Campus Lagoas-Marcosende, E-36310, Vigo, España. mih76@uvigo.es
authors.forename: M Iftikhar
authors.initials: MI
authors.lastname: Hussain
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Reigosa
mesh_terms: D001583:Benzoxazoles / Q000494:pharmacology; D002244:Carbon / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002934:Cinnamates / Q000494:pharmacology; D005453:Fluorescence; D006358:Hot Temperature; D009995:Osmosis / Q000187:drug effects; D010675:Pheromones / Q000494:pharmacology*; D055668:Photochemical Processes / Q000187:drug effects*; D017785:Photons; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D063245:Plant Development; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D010944:Plants / Q000187:drug effects / Q000378:metabolism; D013045:Species Specificity; D013312:Stress, Physiological / Q000187:drug effects; D014867:Water / Q000378:metabolism*
chemical_list: D001583:Benzoxazoles; D002934:Cinnamates; D010675:Pheromones; D045332:Photosystem II Protein Complex; D014867:Water; C029010:cinnamic acid; D002734:Chlorophyll; C017057:benzoxazolone; D002244:Carbon