SYMBIOTIC NITROGEN FIXATION IN ORGANIC FARMING

U poljoprivrednoj proizvodnji dušik je vrlo često osnovni ograničavajući čimbenik rasta i razvoja biljaka, a s time i postizanja optimalnih prinosa. Najveće zalihe ovog elementa nalaze se u atmosferi, gdje je dušik u molekularnom obliku kojeg biljke nisu u mogućnosti usvojiti i iskoristiti. Nedostupan dušik iz atmosfere se kroz proces fiksacije veže u nove spojeve te na taj način postaje dostupan mikroorganizmima i biljkama da ih iskoriste za svoje metaboličke potrebe. Simbiotska fiksacija dušika najznačajnija za poljoprivrednu proizvodnju nastaje kao rezultat simbiotskih interakcija između kvržičnih bakterija i leguminoza, nakon čega slijedi infekcija i nodulacija. U kvržicama, uz prisutnost enzima nitrogenaze dolazi do procesa fiksacije dušika u kojem se atmosferski dušik prevodi u amonijak kojeg biljka dalje uključuje u svoj metabolizam te ga iskorištava za svoje raznovrsne potrebe. U ekološkoj poljoprivrednoj proizvodnji koja je koncipirana na način da teži očuvanju prirode i okoliša, jedno od osnovnih načela je sjetva leguminoznih usjeva jer na taj način poljoprivredno tlo obogaćujemo dušikom te potičemo povećanje i održanje njegove plodnosti što u konačnici donosi mnogostruke pozitivne ekonomske i ekološke učinke.In agricultural production nitrogen is the main limiting factor for growth and development of plants and thereby also achieving optimum yield. The largest stock of this element is in the atmosphere, where nitrogen is in a molecular form which plants are not able to uptake and use. The proceesses of nitrogen fixation are defined as processes in which unavailable nitrogen from the atmosphere is transformed into new compounds, and thereby becomes available to microorganisms and plants to use them for their own metabolic needs. Symbiotic nitrogen fixation which is of the greatest importance for agricultural production occurs as a result of symbiotic interactions between the plants from the family Leguminosae and root nodule bacteria. Symbiotic interaction begins by mutual recognition of appropriate rhizobia and legumes, followed by infection and nodulation. In the nodule, with the presence of nitrogenase enzyme, the process of nitrogen fixation occures in which atmospheric nitrogen is transformed to ammonia which plant can include in its metabolism and use it for their various needs. In organic farming, which is designed to preserve the nature and environment, one of the basic principles is cultivation of legume crops. In this way agricultural soil is enriched with nitrogen, stimuling increase and maintainance of soil fertility which has multiple positive economic and environmental effects

Significant mycotoxigenic fungi in agricultural production

Mikotoksini su otrovni sekundarni metaboliti gljiva. Njihova biosinteza ovisit će ne samo o vrsti i soju gljive već i o abiotskim uvjetima okoliša. Ingestija mikotoksina uzrokuje niz vrlo teških oboljenja koje mogu završiti i letalnim ishodom. U svakodnevnoj poljoprivrednoj praksi stoga je neophodna antifungalna i antimikotksikogena prevencija i dekontaminacija.Mycotoxins are toxic secondary metabolites of fungi. Their biosynthesis depends not only on the type and strain of fungus, but also on abiotic environmental conditions. Ingestion of mycotoxins causes a number of very serious diseases that can result in lethal outcomes. Antifungal and antimycotoxigenic prevention and decontamination is therefore essential in everyday agricultural practices

Toxicity of Fusarium Toxins

Plijesni roda Fusarium jedni su od najčešćih kontaminanata žitarica u poljoprivrednoj proizvodnji u agroekološkim uvjetima Republike Hrvatske. Fusarium sp. metaboliziraju sekundarne toksične metabolite-mikotoksine koji mogu uzrokovati akutna i kronično toksična djelovanja na ljude i životinje. Kontaminacija usjeva Fusarium vrstama može nastati prije žetve (na polju), ali i poslije žetve (u skladištima i silosima). Posljedično tome evidentna je i kontaminacija žitarica i uskladištenih proizvoda Fusarium toksinimaFusarium fungi are among the most common contaminant of cereals in agricultural production in agroecological conditions of the Republic of Croatia. Fusarium sp. metabolize toxic secondary metabolites-mycotoxins that can cause acute and chronic toxic effects on humans and animals. Fusarium contamination of crop species can occur before harvest (the fi eld), and after harvest (in warehouses and silos). Consequently, contamination of crops and stored products with Fusarium toxins is evident

Effects of Irrigation and Bioproducts of Microbial Origin on Nematode Community and Mycorrhizal Root Colonization in Soybean

Soybean (Glycine max L. Merr) is the most important legume and threaten by diverse pests and diseases. Complex interactions among rhizosphere organisms are found in all agro-ecosystems. Results of these interactions can be positive and/or negative in terms of plant production. Soil nematode community consists of different trophic groups of nematodes. Nematodes are the most abundant soil invertebrates. Several nematode species penetrate soybean roots as parasites, and can cause loss in yields. Arbuscular mycorrhiza fungi are obligate plant symbionts that colonize soybean roots naturally. The aim of the study was to evaluate effects of irrigation and amendments of bioproducts containing beneficial soil microorganisms (ABM) on nematode community and mycorrhizal root colonization in soybean. Field experiments were conducted in soybean in 2013 in Osijek, Croatia. The plots were either rain fed or irrigated to 60-100% field water capacity (FWC). We tested soil amendments and soil + foliar amendments of three commercial products containing beneficial organisms. Average number of nematodes per soil sample varied from 186,67 (soil ABM in non-irrigated plots) to 297,57 (soil+foliar ABM in plots with 60-100% FWC), and there were no significant differences between the treatments. Bacterial feeding nematodes were the most abundant, while plant parasitic genus Pratylenchus was the most abundant among other plant parasitic nematodes. There was no clear influence of any of the treatments on soil nematode community. Amendments of the bioproducts increased mycorrhizal root colonization in rain fed plots, while it decreased the mycorrhizal root colonization when soybeans were irrigated. Irrigation increased mycorrhizal root colonization in plots without amendments of the bioproducts, and mycorrhizal colonization differed significantly between the sampling dates. Further research is needed to determine if irrigation alters the potential of mycorrhiza to colonize the roots

INHIBITION OF GROWTH OF SIGNIFICANT MYCOTOXIGENIC FUNGI BY ANTIFUNGAL AGENTS IN ANIMAL FEED

Krmne smjese pohranjene u skladišta potrebno je zaštititi od kontaminacije gljivama i njihovim otrovnim sekundarnim metabolitima. Značajni fitopatogeni, koji na zrnju žitarica dospijevaju u skladišta i silose, ubrajaju se Fusarium verticillioides i Fusarium graminearum producenti fumonizina i trihotecena. U ovom je istraživanju ispitana učinkovitost više različitih smjesa tvari antifungalnih i antimikotoksikogenih osobina u supresiji rasta i biosintezi mikotoksina navedenih gljiva u stočnoj hrani. Najbolji učinak u inhibiciji rasta ostvaren je s kombinacijom butiliranog hidroksianisola, propil parabena i timola u ukupnoj koncentraciji od 700 μg g-1. Međutim primjenom navedenih tvari, u dvostruko manjoj koncentraciji, zabilježena je stimulirana biosinteza fumonizina B1 i B2. Kod formuliranja kombinacija optimalnog supresivnog učinka u uvjetima skladištenja treba uzeti u obzir niz činitelja od abiotskih faktora do biotskih interakcija.Concentrate mixtures stored in storages need to be protected from contamination by fungi and their toxic secondary metabolites. Significant phythopathogenic fungi in Croatia are Fusarium verticillioides and Fusarium graminearum producers of trichothecenes and may occur in storages on the grain cereals. In this research, influence of different antifungal and antimycotoxigenic mixtures on growth and mycotoxins synthesis of these fungi was investigated in concentrate mixtures. The most effective inhibition of growth was achieved with a mixture of butylated hydroxyanisol, propyl paraben and thymol in the total concentration of 700 μg g-1. However it was recorded that application of these substances in half the concentration stimulated biosynthesis of fumonisins B1 and B2. Results indicate variety of factors from abiotic conditions to biotic interactions that should be taken into account when formulating combinations with optimal suppressive effect in storage conditions

Važnost plodoreda i bionematocida u suzbijanju Meloidogyne hapla i Paratylenchus bukowinensis u mrkvi i peršinu

Suzbijanje i održavanje razine populacije biljno parazitskih nematoda ispod ekonomskoga praga štetnosti u korjenastom povrću zahtijeva integrirani pristup primjene agrotehničkih mjera i bioloških sredstava za zaštitu bilja jer kemijski nematocidi nisu dozvoljeni. Ciljevi istraživanja bili su utvrditi utjecaj plodoreda na populaciju Meloidogyne hapla (sjeverna nematoda korijenovih kvržica) i učinkovitost bionematocida NemakeyTM u suzbijanju Paratylenchus bukowinensis (igličaste nematode). Pokus je postavljen u ljetnom usjevu mrkve i peršina tijekom 2016. godine u Tvrđavici kod Osijeka. Populacija M. hapla smanjena je ispod ekonomskoga praga štetnosti uvođenjem kupusnjača u plodored koje su uzgajane na foliji. Prije sjetve mrkve i peršina, populacija P. bukowinensis kretala se od 155 do 470 nematoda u 100 mL tla, a vrhunac populacije od 217 do 920 nematoda u 100 mL tla utvrđen je pri vađenju. Bionematocid je bio slabo učinkovit u suzbijanju populacije igličastih nematoda u mrkvi. Utvrđena su ekonomski značajna oštećenja korijena mrkve (63 %) i peršina (43 %) od P. bukowinensis. Simptomi oštećenja mrkve i peršina od igličastih nematoda vrlo su slični simptomima napada nematoda korijenovih kvržica pri čemu je korijen biljke deformiran, ali nema kvržica. Koliko nam je poznato, do sada u RH nisu opisana u literaturi znatna oštećenja korjenastoga povrća od igličastih nematoda.The management of plant parasitic nematodes in root vegetable crops requires an integrated approach of the application of agro‐technical measures and biological pesticides, since chemical nematicides are not allowed. This study was undertaken to assess the impact of the four‐year crop rotation on the population of Meloidogyne hapla (northern root knot nematode) and efficiency of bionematicide NemakeyTM in suppressing population of Paratylenchus bukowinensis (pin nematode). The research was carried out in Tvrđavica in 2016, in the summer crops of carrots and parsley. Populations of root knot nematodes were reduced when cabbage, grown on plastic was introduced in crop rotation. Populations of P. bukowinensis ranged from 155 to 470 nematodes in 100 mL of soil prior sowing of carrot and parsley, and the peak of the population was at harvest, when 217 to 920 nematodes in 100 mL of soil were detected. Bionematicide did not suppress population of pin nematodes, and both crops suffered minimum of 50% of yield damage. Symptoms of pin nematode and root knot nematode damage are similar, whereas pin nematodes do not cause formation of root galls and development of secondary roots. To the best of our knowleedge, these are the first findings of economically important damages from P. bukowinensis in Croatia on carrots and parsley

APPLICATION OF Galega orientalis IN BIOGAS PRODUCTION

Kodigestija svježe svinjske gnojovke i krmne biljke Galega orientalis Lam. pro¬vedena je s ciljem utvrđivanja energetskog potencijala Galega orientalis za proi¬zvodnju bioplina te usporedbe s nekim važnijim sirovinama koje se primjenjuju u tehnologiji bioplina. Galega orientalis je višegodišnja krmna leguminoza zanimljiva zbog svoje dugovječnosti (7-15 godina), izdržljivosti i otpornosti te jednostavne i ekonomične proizvodnje. Istraživanje je provedeno pri mezofilnim uvjetima u diskontinuiranim reaktorima u trajanju od 61 dana. Prije početka i nakon fermentacije utvrđena su kemijska svojstva supstrata – pH, suha tvar (ST), organska tvar (OT), organski ugljik i organski dušik, te P, K, Ca i Mg u postfermentiranom ostatku s ciljem utvrđivanja mogućnosti daljnjeg korištenja kao organskog gnojiva. Utvrđen je prinos i kemijski sastav proizvedenog bioplina. Prosječni prinos bioplina kontrolne skupine iznosio je 0,219 m3/kg OT a eksperimentalne skupine (uz dodatak leguminoze) 0,610 m3/kg OT. Prema prosječnom sastavu ispitivani uzorci nisu se značajno razlikovali. Prosječni udio metana iznosio je 62,6% u kontrolnoj skupini a u eksperimentalnoj 61,9%.Co-digestion of fresh pig slurry and fodder Galega orientalis Lam. was conducted to determine the energetic potential of Galega orientalis for biogas production and to compare it with some crucial feedstock which are used in the production of biogas. Galega orientalis is a perennial forage legumes, interesting because of its longevity (7-15 years), durability, resistance and simple and economical production. The experiment was conducted in mesophilic conditions in discontinuous reactors with retention time of 61 days. Before and after fermentation the chemical parameters of substrates were determined – pH, total solids (TS), volatile solids (VS), organic carbon and organic nitrogen, elements P, K, Ca and Mg in post fermented residuum with the aim of determining the possibility of further use as organic fertilizer. The biogas yield and its chemical composition were determined. The average biogas yield of the control group was determined to be 0.219 m3/kg VS while of the experimental group (with legumes addition) it was 0.610 m3/kg VS. According to the average composition tested samples did not differ significantly. The average methane content was 62.6% in control group and in the experimental group it was 61.9%