Influence of organic fertilization on chemical composition and yield of cultivated nettle

Kopriva (Urtica dioica L.) je samonikla, višegodišnja biljna vrsta široke primjene, značajna po svojoj ljekovitosti, ali i nutritivnim svojstvima. Osim samonikle koprive koja se sakuplja sprirodnih staništa, sve je traženija kultivirana kopriva poznatog i ujednačenog kemijskog sastava. Tijekom uzgoja, na rast i razvoj koprive te dostupnost hraniva utječu biotski (starost biljke), abiotski (klima) i tehnološki čimbenici (gnojidba). Ova nitrofilna vrsta za svoj uzgoj traži veće količine dušika, međutim pretjerana gnojidba dušikom može rezultirati smanjenim udjelom suhe tvari, željeza, ukupnih fenola i askorbinske kiseline. Zbog sve veće upotrebe koprive, u posljednje vrijeme sve se više istražuje uzgoj ove vrste po ekološkim načelima što podrazumijeva upotrebu organskih gnojiva. Cilj istraživanja bio je istražiti utjecaj organske (1. 'Lumbrical'; 2. 'Siforga ') i mineralne gnojidbe (3. NPK 7-20-30) u količini 100 kg N/ha u usporedbi s kontrolom (4. bez tretmana) na rast, razvoj i sadržaj specijaliziranih metabolita koprive sađene u jesenskom (2020.) i proljetnom (2021.) roku. Iz provedenog istraživanja, može se zaključiti da je na morfološka svojstva kao i mineralni sastav te sadržaj vitamina C i antioksidacijski kapacitet veći utjecaj imao jesenski rok sadnje, dok je na sadržaj fenolnih spojeva i prinos koprive veći utjecaj imao proljetni rok sadnje. Također, može se zaključiti da je na više istraživanih komponenti (prinos, masu herbe po sadnom mjestu, širinu lista te količinu N, Ca i Mg) veći utjecaj imala organska gnojidba u odnosu na mineralnu gnojidbu.Stinging nettle (Urtica dioica L.) is a widespread wild perennial plant species important for its medicinal properties and nutritional properties. In addition to wild nettle collected from natural habitats, cultivated nettle with known and consistent chemical composition is increasingly in demand. In cultivation, the growth and development of stinging nettle and the availability of nutrients are influenced by biotic (plant age), abiotic (climate) and technological factors (fertilization). This nitrophilous species requires higher amounts of nitrogen for its cultivation. However, excessive nitrogen fertilization can result in reduced dry matter, iron, total phenols, and ascorbic acid content. Due to the increasing use of nettle, more research has recently been conducted on growing this species according to organic principles, including the use of organic fertilizers. The aim of the study was to investigate the effects of organic (1. 'Lumbrical'; 2. 'Siforga') and mineral fertilizers (3. NPK 7-20-30) at the rate of 100 kg N ha-1 compared to the control (4. unfertilized) on the growth, development and specialized metabolites of nettles planted in autumn (2020) and spring (2021). From the studies, it can be concluded that morphological characteristics as well as mineral composition, content of vitamin C and antioxidant capacity were higher influenced by fall planting, while phenolic compound content and nettle yield were higher influenced by spring planting. It can also be concluded that organic fertilization had a higher influence on several studied components (yield, mass of herbs per planting site, leaf width, and amount of N, Ca, and Mg) compared to mineral fertilization