Allelopathy

Alelopatija je biološki fenomen koji se odnosi na pozitivan i uglavnom negativan utjecaj organizma (najčešće biljaka) na rast i razvoj drugog organizma ispuštanjem alelokemikalija u okoliš. Biljna alelopatija je zapravo jedan od načina kako biljka preživljava u prirodi te smanjuje kompeticiju okolnih biljaka. Alelokemikalije su zapravo sekundarni metaboliti, spojevi koje biljka ne koristi za svoj metabolizam, već su to nusprodukti. Među svim sekundarnim metabolitima, fenoli su najčešće alelokemikalije, a nastaju šikimatskim i malonatnim putem. Puno je različitih i zanimljivih primjera alelopatije, u radu su navedeni: alelopatija kao mehanizam invazije biljke Typha angustifolia, alelokemikalije ispuštene iz biljaka riže, alelokemikalije ispuštene iz crnog oraha i dr. S agronomskog gledišta, alelopatija je važna jer se poneki usjevi, npr. riža, koriste kao prirodni herbicidi protiv rasta korova. Osim ciljnih organizama, alelopatija također pogađa i ne-ciljne organizme. Ekološki učinci, nadalje, očituju se u inhibiciji mikrobnih simbioza (mikoriza, fiksacija dušika), promjeni u populaciji i zajedničkim strukturama, genotipske varijacije u biljnim populacijama, invazivne vrste i dr.Allelopathy is a biological phenomenon where one plant inhibits the growth and development of another plant through the release of chemicals in the environment. In essence, plant allelopathy is used as a means of survival in nature, reducing competition from plants nearby. Allelochemicals in fact are secondary metabolites, which are not required for metabolism of the allelopathic organism. Phenols are the most important category of the many secondary metabolites implicated in plant allelopathy. Phenolic compounds arise from the shikimic and malonat acid metabolic pathways in plants. There are many interesting examples of allelopathy: allelopathy as a mechanism for the invasion of Typha angustifolia, allelochemicals released from rice plants, allelochemicals released from black walnuts and others. From an agronomic point of view, allelopathy is important because some weed plants like rice are used as natural herbicids against crop production. Apart from target plants, nontarget plants are affected by allelopathy too. Other ecological effects are evident through inhibition of their microbial symbionts such as mycorrhiza and nitrogen fixing bacteria, changes in population and community structure, then changes in genotypic variation in plant populations, invasive plants etc