| Abstract | Cilj ovog rada je istražiti mogućnost smanjenja mineralne dušične gnojidbe primjenom nitrofiksirajućih bakterija koristeći suvremene tehnološke metode. U poljoprivrednoj proizvodnji dušik je važan element za rast i razvoj biljaka a time i za postizanje optimalnih prinosa. Najveće zalihe ovog elementa nalaze se u atmosferi, gdje je dušik u molekularnom obliku kojeg biljke nisu u mogućnosti usvojiti i iskoristiti. Biološka fiksacija dušika je proces u kojem posebne skupine mikroorganizama (nitrofiksirajuće bakterije) usvajaju elementarni dušik iz atmosfere i preko enzima nitrogenaze ga reduciraju do amonijaka čime dušik postaje raspoloživ biljkama za potrebe njihovog metabolizma. Prema odnosu mikroorganizama i viših biljaka nitrofiksacija može biti slobodna, asocijativna i simbiotska. Kod slobodne nitrofiksacije mikroorganizmi nisu direktno, histološki povezani sa višim biljkama, već su slobodni u zemljištu ili vodi, dok se asocijativna fiksacija dušika odvija uz pomoć mikroorganizama koji žive na samoj površini korijena ili u korijenu biljke. Najznačajniji tip simbiotske fiksacije dušika za poljoprivredna tla je fiksacija dušika koja nastaje kao rezultat simbioze između bakterija iz rodova Rhizobuim, Bradyrhizobuim, Sinorhizobium i biljaka većinom iz porodice Leguminosae. Slobodna fiksacija dušika u tlu uglavnom se javlja kao rezultat aktivnosti saprofitskih bakterija iz roda Azotobacter i Clostriduim, ali i nekoliko drugih rodova slobodno živućih bakterija i cijanobakterija, dok su najznačajniji asocijativni nitrofiksatori bakterije iz roda Azospirillum. Biološkom fiksacijom dušika se osigurava biljkama dovoljna količina dušičnog hraniva, a u potpunosti se udovoljava zahtjevima gospodarenja tlom kao što su: produktivnost, sigurnost, zaštita prirodnih resursa i ekonomičnost. Većom uporabom biopreparata koji sadrže efikasne sojeve nitrofiksirajućih bakterija, kao i razvojem vrhunskih sorti legimnoza može se u budućnosti očekivati smanjenje upotrebe kemijskih gnojiva i pesticida i povećanje učinkovitosti poljoprivredne proizvodnje |
| Abstract (english) | The aim of this paper is to investigate the possibility of reducing mineral nitrogen fertilizers with the application of nitrogen-fixing bacteria, using modern technological methods. In agricultural production, nitrogen is an important element for the growth and development of plants and, thus it helps achieve optimal yields. The largest reserves of this element can be found in the atmosphere, where the nitrogen exists in its molecular form, which plants are not able to take and utilize. Biological nitrogen fixation is a process in which specific groups of micro-organisms (nitrogen-fixing bacteria) take elemental nitrogen from the atmosphere and with the nitrogenase enzyme reduce it to ammonia, which becomes available to plants for their metabolism. According to the relation of microorganisms and higher plants, nitrogen fixation can be free, associative and symbiotic. At free nitrogen fixation microorganisms are not directly, histologically connected to higher plants, but they are free in soil or water, while the associative nitrogen fixation takes place with the help of micro-organisms living on the surface of the root or in the root of the plant. The most important type of symbiotic nitrogen fixation for agricultural soils is the nitrogen fixation that occurs as a result of the symbiosis between the bacteria of the genera Rhizobuim, Bradyrhizobuim, Sinorhizobium and the plants, mostly of the family Leguminosae. The free nitrogen fixation in the soil mainly occurs as a result of saprophytic bacteria of the genus Azotobacter and Clostriduim, but also several other genera of free-living bacteria and cyanobacteria, while the most important associative nitrogen-fixing bacteria are those of the genus Azospirillum. Biological nitrogen fixation ensures a sufficient amount of nitrogen nutrients for the plants, and fully meets the requirements of land management, such as productivity, safety, protection of natural resources and economy. With the increased use of biopreparations containing effective strains of nitrogen-fixing bacteria, as well as with the development of the top-quality varieties of leguminosae it can be expected that in the future we will reduce the use of chemical fertilizers and pesticides and that we will increase the efficiency of agricultural production. |
